Sage Journals: Discover world-class research

Abstract

Historically, glaciers have been seen as pristine environments. However, recent research has shown that glaciers can accumulate and store contaminants over long timescales, through processes such as atmospheric deposition, sedimentation, glacial hydrology and mass movements. Studies have identified numerous anthropogenically derived contaminants within the global cryosphere, including the six we focus on here: fallout radionuclides; microplastics; persistent organic pollutants; potentially toxic elements; black carbon and nitrate-based contaminants. These contaminants are relatively well-studied in other environments; however, their dynamics and role in glaciated systems is still poorly understood. Therefore, it is important to assess and quantify contaminant levels within the cryosphere, so that current and future threats can be fully understood and mitigated. In this first progress report (Part I: Inputs and accumulation), we review the current state of knowledge of six of the most common anthropogenic contaminants found in the cryosphere, and consider their sources, transportation, accumulation and concentration within glacial systems. A second progress report (Part II: Release and downstream consequences) will outline how these contaminants leave glacial systems and the consequences that this release can have for communities and ecosystems reliant on glacial meltwater.

Keywords

Cryosphere anthropogenic contaminants cryoconite pollution water quality glacier glacial accumulation environmental quality

I Introduction

Glaciers and ice sheets make up 10% of the Earth’s surface and are often perceived as timeless and unspoilt environments (Hedblom et al., 2020), storing nearly 80% of the planet’s freshwater (DeBeer et al., 2020). However, research has shown that glacial systems can receive and amass contaminants from external sources, which have been deposited onto the ice surface via processes including: precipitation, atmospheric transfer and anthropogenic activities. These contaminants are substances that can be harmful to people and the environment when introduced into air, water, soil or food. The considerable lifespan of glaciers, plus the slow rate of movement of sediment and other materials through glacier systems, means that they have the potential to accrue contaminants continuously for up to a millennium, potentially to levels above the threshold for environmental concern (Port of London Authorities, 2021).

Understanding global and local transportation and accumulation mechanisms helps us to build the foundations of our knowledge so that we can identify research gaps and areas of future concern for contamination in glacial environments. In this report (Part I), we review current empirical research and understanding of six anthropogenic contaminants commonly identified within the cryosphere, including key sources, and modes of transportation, deposition and accumulation in glacial environments. We also consider the main release processes for these contaminants and their potential downstream impacts (Part II). Figure 1 depicts the narrative of both of these reports.

Figure 1.

The scope and framing of these two progress reports. Asterisks denote either *Discussed in Part I, or **Discussed in Part II.

II Contaminants in glaciated environments

The definition of anthropogenic contaminants is not entirely clear, as many contaminants are produced naturally, in addition to being anthropogenically derived. For the purpose of this paper, ‘anthropogenic contaminants’ include those which have been found within the cryosphere that are either: 1) human-made; 2) those that have been influenced and enhanced by anthropogenic activities, such as mining, agriculture and industry and/or 3) those mobilised by rapid deglaciation due to climate change. Here, we focus on six of the large contaminant classes identified in glacial environments across the globe (Table 1): black carbon (BC); fallout radionuclides (FRNs); potentially toxic elements (PTEs); microplastics; nitrogen-based contaminants (NBCs) and persistent organic pollutants (POPs).

Table 1.

Grey shading indicates the source(s) (N = natural, H = human), mode(s) of transportation and deposition (Atm = atmospheric, Eco = Ecological, Geo = geological, Ant = anthropogenic activities) and scale(s) (L = local, R = regional, G = global) of contaminant classes found in glaciated environments.

2.1 Black carbon

Black Carbon (BC) is a product of incomplete combustion, such as automobile exhausts, crop burning and forest fires (Gramsch et al., 2020; Stohl et al., 2007; Treffeisen et al., 2007). Biomass burning has been found to be the primary source of cryospheric BC globally (Bond et al., 2013; Crutzen and Andreae, 2016). The frequency and intensity of wildfires are expected to increase as our climate warms (Dupuy et al., 2020; Halofsky et al., 2020) and so BC deposits on glaciers are also likely to increase. For BC to fall in significant quantities on a glacier, typically the source must be within several hundred kilometres. This causes particular issues for Andean glaciers receiving BC from Amazonian fires (Magalhães et al., 2019; Rowe et al., 2019) and in the Himalayas from biomass burning in India (Gul et al., 2021; Panicker et al., 2021). Similarly, glaciers close to cities and urbanised areas are more susceptible to BC contamination due to exhaust fumes and industry (Gramsch et al., 2020; Rowe et al., 2019). Elevated concentrations of BC deposits on glaciers have also been linked to nearby cities where populations use older, less energy efficient vehicles (Cereceda-Balic et al., 2019; Liu et al., 2019; Natural Resources Defence Council, 2014), for example, on glaciers of the Cordillera Real, Bolivia (Wiedensohler et al., 2018).

Research on BC contamination within the cryosphere has mainly focused on its capacity to alter precipitation and regional weather patterns (Li et al., 2016; Liu et al., 2015; Targino et al., 2009; Wang et al., 2018). However, the impacts of BC in other environments have been found to have mutagenic, carcinogenic and teratogenic effects on humans and animals (Guzzella et al., 2016), as well as reducing plant productivity (Foereid et al., 2011; Major et al., 2010). Furthermore, BC deposited on glaciers decreases the albedo of the ice due to the dark nature of the particles, thus increasing the rate of glacial melt and subsequently the release of other legacy contaminants (Gramsch et al., 2020; Kang et al., 2020: 202; Santra et al., 2019). Unlike other contaminants, the short atmospheric lifespan of BC means that it has a limited geographical window in which to spread. Therefore, targeting the reduction of BC emissions directly at the source would help to ensure that risk of BC contaminant release during glacier recession is minimised in the future.

2.2 Fallout radionuclides

Fallout radionuclides (FRNs) have both natural and artificial origins, such as cosmic radiation, weapons testing and release from nuclear power incidents, for example, Chernobyl and Fukushima (Appleby, 2008; Onda et al., 2020). There is evidence that even low to moderate doses of FRNs within drinking water can increase cancer risk and genetic malformations (WHO, 2008). FRNs have been found in most regions of the global cryosphere, but research has predominantly focused on activity in the northern hemisphere due to the location of many FRN sources, including areas such as the European Alps, Canada, Svalbard, Scandinavia and the Caucasus (Baccolo et al., 2020; Clason et al., 2021; Łokas et al., 2016, 2018, 2021; Owens et al., 2019). FRNs found in high concentrations include ¹³⁷Cs, ²⁴¹Am and ²¹⁰Pb, with some of the highest concentrations found in cryoconite, an organic rich glacial sediment (Baccolo et al., 2020; Łokas et al., 2019). Studies conducted soon after Chernobyl expected ¹³⁷Cs to reach ‘safe’ levels within 20–30 years (i.e. 2007–2017) based on the half-life of ¹³⁷Cs (Davidson et al., 1987; Huda et al., 1988). However, research recently found mean activities of 1900–2600 Bq kg⁻¹ of ¹³⁷Cs in European cryoconite (Baccolo et al., 2020), which are above safe levels as defined by the World Health Organization (WHO, 2008), demonstrating that our current assumptions and known understanding of FRN contamination may not be comprehensive enough for environmental risk assessments in glaciated regions. While some FRNs are decreasing in the environment due to their half-life (e.g., ¹³⁷Cs; half-life of ∼30 years), others are increasing as they are produced in response to the decay of their parent radionuclide. This means FRNs will persist in the environment for multiple generations, impacting on both ecosystem and human health in the future from release into meltwaters, especially for local communities.

2.3 Potentially toxic elements

The term potentially toxic elements (PTEs) describes metals and trace elements that are known to be environmentally toxic above certain concentrations, such as arsenic, mercury, chromium and lead (Tchounwou et al., 2012; Zhang et al., 2019). They can have natural origins, such as weathering of rocks, forest fires and volcanic eruptions (Łokas et al., 2016), along with anthropogenic origins, such as industry, mining, fossil fuel combustion and agriculture (Łokas et al., 2019). Furthermore, geological erosion from glaciers mobilises PTEs that were originally stored in rocks and can increase their levels in glacial meltwaters and proglacial sediments, such as iron in Peruvian glacial environments (Guittard et al., 2015, 2017).

Concentrations of most PTEs found in glaciated environments are at levels close to, or higher than those described in the European Environmental Quality Standards (Port of London Authorities, 2021). The susceptibility to bioaccumulation of PTEs at all trophic levels and biomagnification in higher trophic levels has led to concerns about the impact on downstream ecosystems and communities that rely on glacial meltwater (Binda et al., 2020; Fortner et al., 2011; Zhu et al., 2020). Human activities have led to a nearly tenfold increase in the deposition of PTEs since the start of the industrial era (Casella et al., 2022; Łokas et al., 2019). Intensified mining activities and the demand for global resources for manufacturing and production is likely to increase the quantity of PTEs in the future (Tchounwou et al., 2012). This could be detrimental to plants, animals and humans, especially with bioaccumulation within the food chain (AMAP, 2005). More research is needed on the potential uptake of PTEs in glacial-riverine systems and downstream aquatic environments, including the interactions between PTEs and other contaminants.

2.4 Microplastics

Microplastics are human-made, petroleum-based particles <5 mm (Liss, 2020) resulting from the breakdown of macroplastics. Their small size makes them susceptible to long-range atmospheric transport and mobilization within hydrological systems. As such, microplastics have been found in all environmental systems sampled to date (Allen et al., 2019; Dris et al., 2016; Haixin et al., 2022; Jiang et al., 2019; Nelms et al., 2018). Previous studies have investigated microplastics within sea ice (Geilfus et al., 2019; Kanhai et al., 2020; Kelly et al., 2020; Obbard et al., 2014; Peeken et al., 2018), but only recent studies have started to look at the presence of microplastics in terrestrial glacier systems (Ambrosini et al., 2019; Ásmundsdóttir and Scholz, 2020; Cabrera et al., 2020; Napper et al., 2020; Stefánsson et al., 2021). Microplastics can enter glacial landscapes via precipitation or anthropogenic interactions, but there is currently a lack of research on of the impact of microplastics for humans and ecosystems within glacio-fluvial catchments. The longevity of the particles mean that they will continue to be present in the environment for numerous generations, thus it is important that we better understand the potential socio-environmental implications

2.5 Nitrogen-based contaminants

Nitrogen-based contaminants (NBCs) refer to ionic forms of dissolved nitrogen, including nitrates and ammonium. High concentrations of NBCs have been found in glaciated environments, due to atmospheric transfer and direct deposition from animal presence on glaciers (Barman and Naik, 2017; Goyenola et al., 2020; Lori et al., 2018; Ollivier et al., 2011; Yang et al., 2015; ZhenZhu et al., 2019). NBC levels are increased by anthropogenic activities involving nitrogen-based compounds, such as fertilizers and by-products from agriculture, septic systems, and bird or livestock manure (Hastings et al., 2013; Hong et al., 2011; Howarth et al., 2012; Kim et al., 2014; Meter et al., 2016). High concentrations of NBCs in glacial meltwater could have significant impacts on downstream ecosystems and water quality, including changes to pH, increased algal and bacterial activity, reduced oxygen levels and increased toxicity from NBCs such as ammonia (Chen et al., 2019; Williams et al., 1998). As global populations continue to increase, NBC levels will rise as agricultural practices increase to meet the global food demands.

2.6 Persistent organic pollutants

Persistent organic pollutants (POPs) are a group of 28 chemicals that have been found to have adverse impacts on humans and ecosystems (UNEP, 2017). Most POPs result from the use of pesticides, solvents, pharmaceuticals and industrial chemicals. However, some POPs are naturally occurring in volcanoes and some biosynthetic pathways (El-Shahawi et al., 2010). The terrestrial spatial variability and bioaccumulation of POPs has been widely studied and is recognised internationally as a chemical risk for food safety (Codex Alimentarius Commission, 2018). POPs are subjected to atmospheric transfer and thus have been detected in places where they had not previously been used, geographically far from their original source (Barra et al., 2005; Zhang et al., 2008), including environments such as polar regions and high-altitude mountain ranges (Daly and Wania, 2005; Wania and Mackay, 1993). The introduction of the Stockholm Convention has led to a reduction in the use of substances containing POPs (UNEP, 2017), however, legacy POP reserves still exist. High concentrations of POPs released into glacial meltwater systems could still pose significant health risks to humans and ecosystems downstream (Santolaria et al., 2015).

III Transport and deposition of contaminants in glaciated environments

Many components of the cryosphere (e.g. sea ice, glaciers, snow, frozen ground) have been found to serve as ‘reservoirs’ for contaminants (Wang et al., 2019). The majority of external sources of contaminants originate from industrialised areas around the globe and are then transported by long-range atmospheric transport, prevailing winds and global circulation patterns (Duncan and Bey, 2004; Knap, 2012; Macdonald et al., 2005; Stohl, 2006). Contaminants are then deposited into glacial environments through windblown dust or wet precipitation (Gabbi et al., 2015; Kozak et al., 2015). There are also more localised mechanisms, such as anthropogenic and ecological activities, that deposit contaminants either directly into glaciated environments, or accumulate them in situ (Figure 2).

Figure 2.

Transport pathways and processes of deposition for contaminants (purple arrows) within glaciated environments, including identification of potential risks into downstream environments (yellow arrows).

3.1 Atmospheric transport

Most of the contaminant classes discussed in Section 2 are prone to degradation within the environment. Their volatility and ability to bond to aerosols means that they are easily transported into the upper atmosphere (Daly and Wania, 2005). The Intertropical Convergence Zone acts as a barrier to particulate contaminants transported in the atmosphere, as the high temperatures and low pressure drives air upwards and back towards the poles, resulting in minimal atmospheric mixing (Schneider et al., 2014). This generally leads to higher concentrations of contaminants in the hemisphere where they originated. For instance, the Chernobyl disaster and numerous weapons testing took place in the northern hemisphere during the last century, and therefore there is a notable difference in FRN concentrations found in glaciers in the northern hemisphere compared to the southern hemisphere (Baccolo et al., 2020).

In addition to polar regions, high-altitude mountain environments can be receptor regions for atmospherically transported contaminants, due to cold condensation processes, promoted by low temperatures and falling snow (Bizzotto et al., 2009; Guzzella et al., 2016). Once in the atmosphere, contaminants are deposited by either wet or dry precipitation. Wet precipitation is the process whereby atmospheric gases mix with suspended water. In the atmosphere, particulates and contaminants are then washed out through rain, snow or fog. This has been noted to be the most efficient fallout mechanism of contaminants, due to the effectiveness of scavenging particulate matter from the atmosphere (Pinglot et al., 2001). For example, areas that received heavy precipitation during the passage of the Chernobyl cloud (29 April to 10 May 1986) were more strongly affected by FRN contamination than areas that received low precipitation (Tieber et al., 2009). Glacial environments in locations that are exposed to high levels of precipitation are prone to increased contaminant deposition from wet precipitation and thus to potential risk from contamination, for example, monsoon rains in the Himalayas, extreme El Niño-Southern Oscillation events in the South American Andes and snowstorms in the Arctic.

Dry deposition is the process of particulates falling from the atmosphere without a hydrological component. This normally occurs when the density of the particulate matter becomes too high and can no longer be carried by atmospheric winds (Wu et al., 1992). Glaciated environments near areas prone to forest fires, volcanic activity and dust storms can be subjected to both higher levels of contamination and sedimentation from dry deposition (Du et al., 2017; Kang et al., 2019; Kozak et al., 2015; Manca et al., 2012; Müller-Tautges et al., 2016). Temperate-zone mountain regions, which tend to receive high levels of precipitation while being close to contaminant sources, are also susceptible to higher accumulation of contaminants from dry deposition. These include the European Alps, which are situated in close proximity to the highly populated and anthropized regions of Europe (Ferrario et al., 2017a; Kelly and Gobas, 2003; Kirchgeorg et al., 2016).

3.2 Geological processes

As glaciers move through landscapes they erode rock surfaces in contact with the ice. Local geomorphology, orography, valley shape, steepness and geologic hardness can all have impacts on both the erosion of rock surfaces by glaciers and the movement of airborne contaminants into atmospheric circulations (Belan et al., 2018; Hawkings et al., 2020; Saavedra et al., 2020). Particle size and the geochemical composition of sediment can also influence contaminant content and distributional characteristics in the sediment (Huang and Lin, 2003). Contaminants within sediments and larger geological debris created by freeze thaw, abrasion and plucking processes are temporarily entombed by glaciers and then distributed downslope along through melting.

A further potential contaminant transfer pathway in glacial systems is acid rock drainage (ARD). This is a chemical reaction between oxygen, water and sulphide minerals such as pyrite, which results in a low pH solution with high concentrations of dissolved metals and PTEs (Duran et al., 2019). ARD can be exacerbated by anthropogenic earth disturbance, for example, mining and construction activities as seen in the Peruvian Andes (Guittard et al., 2017; Santofimia et al., 2017). It also occurs naturally as part of weathering and erosion processes, such as those prominent in glaciated regions. The extent of ARD varies due to localised geomorphology, climate and the distribution of periglacial deposits (Csavina et al., 2011; Dold et al., 2013; Santofimia et al., 2017). However, glacier retreat over certain geologies can lead to ARD and increased levels of contaminant release (Zarroca et al., 2021).

3.3 Localised anthropogenic activities

Awareness that mountain glaciers are expected to continually retreat and vanish (Zekollari et al., 2019), in addition to improved accessibility and an increase in disposable income in many Western societies, means that more individuals are taking part in activities like mountaineering, glacier walks and snow sports (Furunes and Mykletun, 2012; Wang and Zhou, 2019; Welling et al., 2015). This growth in glacier tourism has led to an increase in the direct deposition of contaminants by humans. For example, plastic fibres from outdoor clothing and vehicles can fall onto the ice (Napper et al., 2020), while vehicle use can release BC and PTEs via exhaust particulates and fuel dumps (Amaro et al., 2015; Huddart and Stott, 2020). Furthermore, equipment such as clothing, food containers and empty oxygen tanks, along with other litter, are often left by tourists on glaciers (Parolini et al., 2021). Similarly, the lack of permanent bathroom facilities means that human waste products are often left out in the open (Goodwin et al., 2012). This waste matter can accumulate and release products unwanted by the human body, such as pathogens (Alm et al., 2018), NBCs (Lu et al., 2017) and PTEs (Wang et al., 2012) into the environment (Goodwin et al., 2012). Alongside tourist activity, research and monitoring equipment abandoned on glaciers will eventually melt out into downstream environments or reach the sea via calving. Limited research has been conducted on the impact of legacy equipment for local environments, particularly in glacial systems. Therefore, both the glaciological community and broader scientific community should be mindful of what we introduce to and leave in glaciated environments.

Other anthropogenic activity such as resource extraction can mobilise contaminants into glaciated systems from within the lithosphere (Csavina et al., 2011; Guittard et al., 2017; Li, 2018). This can introduce large quantities of contaminants into glacial environments, especially in areas with informal mining activities such as those used in India (Barve et al., 2011) and Peru (Williams, 2014). Furthermore, farming activities can also promote the deposition of contaminants into glacial systems, notably those associated with fertiliser, herbicide and pesticide use (McIntyre, 2007). This is a particular issue in agriculture intensive areas, such as in the foothills of the Italian Alps (Ferrario et al., 2017b; Rizzi et al., 2019), the Himalayas (Wang et al., 2006) and Qinghai-Tibetan Plateau (Haixin et al., 2022).

IV Contaminant accumulation and concentration mechanisms

Once deposited within glaciated environments, hydrological, geological, and biogeochemical processes can act to accumulate and concentrate contaminants, potentially above probable effect levels (PELs) and other thresholds for concentrations of environmental concern (Port of London Authorities, 2021). Incorporation of contaminants into the snowpack, and subsequently firn and ice, creates layers of legacy contaminants (Pogorzelski et al., 2021). These temporary reservoirs store contaminants until the ice melts, causing concentrated peaks of contamination release during melt periods (Bizzotto et al., 2009; Meyer et al., 2006; Meyer and Wania, 2008; Pogorzelski et al., 2021). This section outlines some of the most common accumulating and concentrating mechanisms for glacial contaminants.

4.1 Transfer by glacial hydrological processes

The large scale movement of meltwater and precipitation through glaciers happens in several ways, including supraglacial, englacial and subglacial channels and spaces (Gooseff et al., 2011; Wright et al., 2014). Small-scale hydrological flows also happen within and in-between ice crystals (Fountain and Walder, 1998). As water moves through ice, it picks up sediment and contaminants and carries them through the system. If the glacier is on top of unfrozen soil or sediment, meltwater reaching the bed can transport contaminants into the substrate, potentially reaching the water table. If the glacier is on an impermeable bedrock or frozen substrate, the meltwater will travel along the basal layer, releasing contaminants in the proglacial area (Eyles, 2006). Glacial lakes and fjords, often situated within close proximity to glaciers, are an efficient accumulating mechanism, becoming repositories for contaminants, which can settle within sediments due to the low velocity of the water (Clason et al., 2021; Mohan et al., 2018; Zhu et al., 2020). These lakes are rapidly growing in response to climate change and glacier retreat (Shugar et al., 2020). Their low turbulence and limited dilution in these sediment sinks means that contaminants can accumulate, posing risks to aquatic life and flora within the vicinity.

The morphology of the ice can also influence the movement of contaminants and sediments. For instance, valley glaciers will move materials through the system much faster than large ice sheet outlet glaciers (Antoniazza and Lane, 2021; Choudhary et al., 2020; Lawson, 1982; Mao et al., 2020). Additionally, melting of the upper layers of snow, firn and ice will expose contaminants stored deeper within the glacier, increasing contaminant accrual and potentially accelerating melting processes (Gul et al., 2021). These mechanisms can create concentrated pockets of contaminant-rich sediment in the lower parts of glaciers, which could be environmentally harmful if released in a short period of time. This may also decrease downstream water quality through the amplification of sedimentary budgets and the increase of sediment and contaminant loads under future melt (Staniszewska et al., 2021).

Understanding the effects of rapid snowpack melt are of great ecotoxicological importance, since predicted anthropogenic climate warming is likely to result in large changes in the magnitude and duration of seasonal snow cover (Houghton, 2001). Rapid melting of snowpack generates higher concentrations of contaminant release into aquatic systems, compared to prolonged melt processes (Bizzotto et al., 2009; Lafrenière et al., 2006). In contrast, reduced snowpack and elevated temperatures, along with summer precipitation, leads to increased glacial melt and subsequent mobility of contaminants into downstream environments (Javadinejad et al., 2020). Hence, it is important for us to fully understand the dynamics and relationship between increased snow melt, environmental change and contaminant release so that we can protect essential water resources from the effects of global temperature rise.

4.2 Accumulation and concentration in cryoconite

Cryoconite is a sediment found on glacier surfaces and comprises both biogenic and geogenic materials (Figure 3). Fine mineral particles within cryoconite, such as silts, clays and organic matter, have adhesive properties that help to bind contaminants to them (Owens et al., 2019). Similarly, the filamentous morphology and sticky nature of microorganisms that live on cryoconite, such as extremophiles, cyanobacteria and microbes, helps cryoconite to entangle debris and contaminants within the sediment (Cook et al., 2016; Huang et al., 2019; Pittino et al., 2018). These microorganisms can also accelerate the decomposition of metal ions into toxic and more bioavailable forms, such as mercury into methylmercury by sulphur-reducing microbes (St. Pierre et al., 2019; Staniszewska et al., 2021). This makes cryoconite very efficient at storing potentially toxic contaminants, which may result in negative downstream effects on glacier-fed ecosystems under climate warming scenarios (Hodson et al., 2010).

Figure 3.

A cryoconite hole on Pastoruri Glacier in the Peruvian Andes. Cryoconite is now known to be an efficient accumulator of contaminants such as fallout radionuclides and heavy metals cryoconite (photography by Wilmer Sánchez Rodríguez, Peru 2020).

Previous research on cryoconite has often focused on microorganism ecosystems and the ability of cryoconite to accumulate nutrients (Poniecka et al., 2020; Poniecka and Bagshaw, 2021). However, recent research has shown that cryoconite can also act as a sink for pollutants including BC, FRNs and PTEs (Clason et al., 2021; Cong et al., 2018; Fortner and Lyons, 2018; Li et al., 2017; Łokas et al., 2018). Larger pockets of cryoconite called ‘cryoconite holes’ vary in size, but typically have dimensions of 10–100cm³ (MacDonell and Fitzsimons, 2008, 2012). They also have the potential to become substantially larger through melting, collapse and merging with other holes (Fountain et al., 2004). Consequently, this accumulates a larger mass of contaminants for as long as there is a source of legacy contaminants within the melting ice, firn, or snow (Bagshaw et al., 2013; Stock et al., 2014). The release of cryoconite into meltwater could act to increase contaminant loads downstream, but more research is required to understand this further.

4.3 Microbial influence on contaminant mobility and fate

Biological processes are often omitted when analysing the mobility and fate of contaminants in the cryosphere. Microorganisms on Alpine glaciers were previously shown to be able to degrade contaminants such as POPs (Margesin et al., 2002) and have more recently been found to degrade even complex organic compounds at low temperatures (Poniecka et al., 2020; Sanyal et al., 2018). Microbial phyla have a major role in controlling the mobility, toxicity and degradation of contaminants, such as FRNs, PTEs and POPs, through the production and turnover of organic matter (Ferrario, et al., 2017b; Iurian et al., 2015; Pittino et al., 2018). This is particularly relevant in places of high microbiological activity, such as cryoconite holes (Poniecka et al., 2020; Simonoff et al., 2007).

Substantial changes to microbial communities could lead to a negative chain of events within the wider environment and higher trophic levels of the food chain (Cappa et al., 2014; Gralka et al., 2020). Bacteria in other environments, such as aquatic ecosystems, have been shown to form biofilms on surfaces of microplastics (Bowley et al., 2021; Oberbeckmann et al., 2015), some of which are able to degrade plastic (Zettler et al., 2013). These biofilms could be detrimental to some ecosystems, but could also be utilised in a positive way to reduce the risk from toxic contaminants (Cappa et al., 2014). Further research is required to better understand and model biological influence on the accumulation and biodegradation of contaminants in glacial environments.

V Summary

Anthropogenic contamination has been detected in glacial and proglacial environments around the globe from various sources and due to a range of transportation and accumulation mechanisms. Previous research has begun to quantify the level and spatial distribution of contaminants within the cryosphere. This progress report has explored the sources and transport pathways of six contaminant classes found in glacial environments and have identified significant gaps in current understanding of the process involved in their accumulation and how this affects contaminant loads in glaciers. More research is required on contaminant transport through anthropogenic, geological and ecological modes so that locoregional risks can be better identified. The next progress report (Part II: Secondary release and downstream consequences) discusses what happens to contaminants once they leave glacial systems through secondary release mechanisms, and the potential risks they could pose downstream for ecosystems and humans in glacial regions.

Footnotes

Acknowledgements

The authors are very grateful to Leigh O’Regan for language editing and proofreading.

Declaration of conflicting interests

The author(s) declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.

Funding

The author(s) received no financial support for the research, authorship, and/or publication of this article.

ORCID iDs

Dylan B Beard

Ewa Poniecka

References

Allen

Phoenix

, et al. (2019) Atmospheric transport and deposition of microplastics in a remote mountain catchment. Nature Geoscience 12(5): 339–344. DOI: 10.1038/s41561-019-0335-5

Alm

Daniels-Witt

Learman

, et al. (2018) Potential for gulls to transport bacteria from human waste sites to beaches. Science of The Total Environment 615: 123–130. DOI: 10.1016/j.scitotenv.2017.09.232

AMAP (2005) AMAP Assessment 2002 00: Heavy Metals in the Arctic. Oslo: Arctic Monitoring and Assessment Programme (AMAP).

Amaro

Padeiro

Mão de Ferro

, et al. (2015) Assessing trace element contamination in Fildes Peninsula (King George Island) and Ardley Island, Antarctic. Marine Pollution Bulletin 97(1): 523–527. DOI: 10.1016/j.marpolbul.2015.05.018

Ambrosini

Azzoni

Pittino

, et al. (2019) First evidence of microplastic contamination in the supraglacial debris of an alpine glacier. Environmental Pollution 253: 297–301. DOI: 10.1016/j.envpol.2019.07.005

Antoniazza

Lane

(2021) Sediment yield over glacial cycles: A conceptual model. Progress in Physical Geography: Earth and Environment. SAGE Publications Ltd: 0309133321997292. DOI: 10.1177/0309133321997292

Appleby

(2008) Three decades of dating recent sediments by fallout radionuclides: a review The Holocene 18, (1). SAGE Publications Ltd: 83–93. DOI: 10.1177/0959683607085598

Ásmundsdóttir

ÁM

Scholz

(2020) Effects of Microplastics in the Cryosphere. In: Rocha-Santos

Costa

Mouneyrac

(eds) Handbook of Microplastics in the Environment. Cham: Springer International Publishing, pp. 1–46. DOI: 10.1007/978-3-030-10618-8_47-2

Baccolo

Łokas

Gaca

, et al. (2020) Cryoconite: an efficient accumulator of radioactive fallout in glacial environments. The Cryosphere 14(2): 657–672. DOI: 10.5194/tc-14-657-2020

10.

Bagshaw

Tranter

Fountain

, et al. (2013) Do Cryoconite Holes have the Potential to be Significant Sources of C, N, and P to Downstream Depauperate Ecosystems of Taylor Valley, Antarctica? Arctic, Antarctic, and Alpine Research 45(4). Taylor & Francis: 440, 454. DOI: 10.1657/1938-4246-45.4.440

11.

Barman

Naik

(2017) Effect of substrate, nutrition and growth regulator on productivity and mineral composition of leaf and pseudobulb of Cymbidium hybrid “Baltic Glacier Mint Ice”. Journal of Plant Nutrition 40(6). Taylor & Francis: 784, 794. DOI: 10.1080/01904167.2016.1201496

12.

Barra

Popp

Quiroz

, et al. (2005) Persistent toxic substances in soils and waters along an altitudinal gradient in the Laja River Basin, Central Southern Chile. Chemosphere 58(7): 905–915. DOI: 10.1016/j.chemosphere.2004.09.050

13.

Barve

Muduli

Prof

(2011) Challenges to Environmental Management Practices in Indian Mining Industries.

14.

Belan

Buchelnikov

Lysova

, et al. (2018) Estimation of the Effect of Meteorological and Orographic Conditions on Aerosol Contamination of the Snow Cover in the South of Tomsk Region. Atmospheric and Oceanic Optics 31: 656–664. DOI: 10.1134/S1024856018060039

15.

Binda

Pozzi

Livio

(2020) An integrated interdisciplinary approach to evaluate potentially toxic element sources in a mountainous watershed. Environmental Geochemistry and Health 42(5): 1255–1272. DOI: 10.1007/s10653-019-00405-4

16.

Bizzotto

Villa

Vaj

, et al. (2009) Comparison of glacial and non-glacial-fed streams to evaluate the loading of persistent organic pollutants through seasonal snow/ice melt. Chemosphere 74(7): 924–930. DOI: 10.1016/j.chemosphere.2008.10.013

17.

Bond

Doherty

Fahey

, et al. (2013) Bounding the role of black carbon in the climate system: A scientific assessment: BLACK CARBON IN THE CLIMATE SYSTEM. Journal of Geophysical Research: Atmospheres 118(11): 5380–5552. DOI: 10.1002/jgrd.50171

18.

Bowley

Baker-Austin

Porter

, et al. (2021) Oceanic Hitchhikers – Assessing Pathogen Risks from Marine Microplastic. Trends in Microbiology 29(2): 107–116. DOI: 10.1016/j.tim.2020.06.011

19.

Cabrera

Valencia

Lucas-Solis

, et al. (2020) A new method for microplastic sampling and isolation in mountain glaciers: A case study of one antisana glacier, Ecuadorian Andes. Case Studies in Chemical and Environmental Engineering 2: 100051. DOI: 10.1016/j.cscee.2020.100051

20.

Cappa

Suciu

Trevisan

, et al. (2014) Bacterial diversity in a contaminated Alpine glacier as determined by culture-based and molecular approaches. Science of The Total Environment 497: 50–59. DOI: 10.1016/j.scitotenv.2014.07.094

21.

Casella

Nevell

Steyne

(eds) (2022) The Oxford Handbook of Industrial Archaeology. New York: Oxford University Press.

22.

Cereceda-Balic

Gorena

Soto

, et al. (2019) Optical determination of black carbon mass concentrations in snow samples: A new analytical method. Science of The Total Environment 697: 133934. DOI: 10.1016/j.scitotenv.2019.133934

23.

Chen

Wang

Zhang

, et al. (2019) Physiological effects of nitrate, ammonium, and urea on the growth and microcystins contamination of Microcystis aeruginosa: Implication for nitrogen mitigation. Water Research 163: 114890. DOI: 10.1016/j.watres.2019.114890

24.

Choudhary

Nayak

Khare

(2020) Source, mobility, and bioavailability of metals in fjord sediments of Krossfjord-Kongsfjord system, Arctic, Svalbard. Environmental Science and Pollution Research 27(13): 15130–15148. DOI: 10.1007/s11356-020-07879-1

25.

Clason

Blake

Selmes

, et al. (2021) Hyper-accumulation of Legacy Fallout Radionuclides in Cryoconite on Isfallsglaciären (Arctic Sweden) and Their Downstream Distribution. preprint, 28 May. Glaciers/Glacier Hydrology. DOI: 10.5194/tc-2021-142

26.

Codex Alimentarius Commission (2018) Code of Practice for the Prevention and Reduction of Dioxin and Dioxin-like PCB Contamination in Foods and Feeds. CXC 62-2006. Available at: https://www.fao.org/fao-who-codexalimentarius/sh-proxy/en/?lnk=1&url=https%253A%252F%252Fworkspace.fao.org%252Fsites%252Fcodex%252FStandards%252FCXC%2B62-2006%252FCXC_062e.pdf (accessed 14 March 2022).

27.

Cong

Gao

Zhao

, et al. (2018) Iron oxides in the cryoconite of glaciers on the Tibetan Plateau: abundance, speciation and implications. The Cryosphere 12(10): 3177–3186. DOI: 10.5194/tc-12-3177-2018

28.

Cook

Edwards

Takeuchi

, et al. (2016) Cryoconite: The dark biological secret of the cryosphere. Progress in Physical Geography: Earth and Environment 40(1): 66–111. DOI: 10.1177/0309133315616574

29.

Crutzen

Andreae

(2016) Biomass Burning in the Tropics: Impact on Atmospheric Chemistry and Biogeochemical Cycles. In: Crutzen

Brauch

(eds) Paul J. Crutzen: A Pioneer on Atmospheric Chemistry and Climate Change in the Anthropocene. SpringerBriefs on Pioneers in Science and Practice. Cham: Springer International Publishing, pp. 165–188. DOI: 10.1007/978-3-319-27460-7_7

30.

Csavina

Landázuri

Wonaschütz

, et al. (2011) Metal and Metalloid Contaminants in Atmospheric Aerosols from Mining Operations. Water, Air, & Soil Pollution 221(1): 145–157. DOI: 10.1007/s11270-011-0777-x

31.

Daly

Wania

(2005) Organic Contaminants in Mountains. Environmental Science & Technology 39(2): 385–398. DOI: 10.1021/es048859u

32.

Davidson

Harrington Stephenson

, et al. (1987) Radioactive cesium from the Chernobyl accident in the Greenland Ice Sheet. Science 237(4815). American Association for the Advancement of Science: 633–634. DOI: 10.1126/science.3603043

33.

DeBeer

Sharp

Schuster-Wallace

(2020) Glaciers and Ice Sheets. In: Goldstein

DellaSala

(eds) Encyclopedia of the World’s Biomes. Oxford: Elsevier, pp. 182–194. DOI: 10.1016/B978-0-12-409548-9.12441-8

34.

Dold

Gonzalez-Toril

Aguilera

, et al. (2013) Acid Rock Drainage and Rock Weathering in Antarctica: Important Sources for Iron Cycling in the Southern Ocean. Environmental Science & Technology 47(12). American Chemical Society: 6129–6136. DOI: 10.1021/es305141b

35.

Dris

Gasperi

Saad

, et al. (2016) Synthetic fibers in atmospheric fallout: A source of microplastics in the environment? Marine Pollution Bulletin 104(1–2): 290–293. DOI: 10.1016/j.marpolbul.2016.01.006

36.

Xiao

Liu

, et al. (2017) Natural vs. anthropogenic sources supply aeolian dust to the Miaoergou Glacier: Evidence from Sr–Pb isotopes in the eastern Tienshan ice core. Quaternary International 430: 60–70. DOI: 10.1016/j.quaint.2015.11.069

37.

Duncan

Bey

(2004) A modeling study of the export pathways of pollution from Europe: Seasonal and interannual variations (1987–1997). Journal of Geophysical Research: Atmospheres 109, D08301. DOI: 10.1029/2003JD004079.

, et al. (2020) Climate change impact on future wildfire danger and activity in southern Europe: a review. Annals of Forest Science 77(2): 35. BioMed Central: 1–24. DOI: 10.1007/s13595-020-00933-5

, et al. (2019) Applications of trace element chemistry of pyrite and chalcopyrite in glacial sediments to mineral exploration targeting: Example from the Churchill Province, northern Quebec, Canada. Journal of Geochemical Exploration 196: 105–130. DOI: 10.1016/j.gexplo.2018.10.006

, et al. (2010) An overview on the accumulation, distribution, transformations, toxicity and analytical methods for the monitoring of persistent organic pollutants. Talanta 80(5): 1587–1597. DOI: 10.1016/j.talanta.2009.09.055

41.

Eyles

(2006) The role of meltwater in glacial processes. Sedimentary Geology 190(1): 257–268. DOI: 10.1016/j.sedgeo.2006.05.018

(2017a) Legacy and emerging contaminants in meltwater of three Alpine glaciers. Science of The Total Environment 574: 350–357. DOI: 10.1016/j.scitotenv.2016.09.067.

, et al. (2017b) Bacteria contribute to pesticide degradation in cryoconite holes in an Alpine glacier. Environmental Pollution 230: 919–926. DOI: 10.1016/j.envpol.2017.07.039.

(2011) Modeling black carbon degradation and movement in soil. Plant and Soil 345(1): 223–236. DOI: 10.1007/s11104-011-0773-3

45.

Fortner

Lyons

(2018) Dissolved Trace and Minor Elements in Cryoconite Holes and Supraglacial Streams, Canada Glacier, Antarctica. Frontiers in Earth Science 6: 31. DOI: 10.3389/feart.2018.00031

, et al. (2011) Elevated stream trace and minor element concentrations in the foreland of receding tropical glaciers. Applied Geochemistry 26(11): 1792–1801. Sources, Transport and Fate of Trace and Toxic Elements in the Environment – IAGS 2009. DOI: 10.1016/j.apgeochem.2011.06.003

47.

Fountain

Walder

(1998) Water flow through temperate glaciers. Reviews of Geophysics 36(3): 299–328. DOI: 10.1029/97RG03579 .

, et al. (2004) Evolution of cryoconite holes and their contribution to meltwater runoff from glaciers in the McMurdo Dry Valleys, Antarctica. Journal of Glaciology 50(168): 35–45. DOI: 10.3189/172756504781830312

49.

Furunes

Mykletun

(2012) Frozen Adventure at Risk? A 7-year Follow-up Study of Norwegian Glacier Tourism. Scandinavian Journal of Hospitality and Tourism 12(4): 324–348. DOI: 10.1080/15022250.2012.748507

, et al. (2015) The impact of Saharan dust and black carbon on albedo and long-term mass balance of an Alpine glacier. The Cryosphere 9(4): 1385–1400. DOI: 10.5194/tc-9-1385-2015

, et al. (2019) Distribution and impacts of microplastic incorporation within sea ice. Marine Pollution Bulletin 145: 463–473. DOI: 10.1016/j.marpolbul.2019.06.029

(2012) Glacial Transport of Human Waste and Survival of Fecal Bacteria on Mt. McKinley’s Kahiltna Glacier, Denali National Park, Alaska. Arctic, Antarctic, and Alpine Research 44(4): 432–445. DOI: 10.1657/1938-4246-44.4.432

, et al. (2011) Hydrological Connectivity of the Landscape of the McMurdo Dry Valleys, Antarctica. Geography Compass 5(9): 666–681. DOI: 10.1111/j.1749-8198.2011.00445.x .

, et al. (2020) Influence of Farming Intensity and Climate on Lowland Stream Nitrogen. Water 12(4). 4. DOI: 10.3390/w12041021

, et al. (2020) Trophic Interactions and the Drivers of Microbial Community Assembly. Current Biology 30(19): R1176–R1188. DOI: 10.1016/j.cub.2020.08.007

, et al. (2020) Black carbon transport between Santiago de Chile and glaciers in the Andes Mountains. Atmospheric Environment 232: 117546. DOI: 10.1016/j.atmosenv.2020.117546

, et al. (2015) Spatiotemporal Variability and Differentiation between Anthropogenic and Natural Contamination of Heavy Metals of Surface Water: A Case Study in the Cordillera Blanca, Peru. Washington, DC: American Geophysical Union

, et al. (2017) Trace-metal contamination in the glacierized Rio Santa watershed, Peru. Environmental Monitoring and Assessment 189(12): 649. DOI: 10.1007/s10661-017-6353-0

, et al. (2021) Black carbon concentration in the central Himalayas: impact on glacier melt and potential source contribution. Environmental Pollution: 275, 116544. DOI: 10.1016/j.envpol.2021.116544

, et al. (2016) POP and PAH contamination in the southern slopes of Mt. Everest (Himalaya, Nepal): Long-range atmospheric transport, glacier shrinkage, or local impact of tourism? Science of The Total Environment 544: 382–390. DOI: 10.1016/j.scitotenv.2015.11.118

, et al. (2022) Land-use patterns determine the distribution of soil microplastics in typical agricultural areas on the eastern Qinghai-Tibetan Plateau. Journal of Hazardous Materials 426: 127806. DOI: 10.1016/j.jhazmat.2021.127806

(2020) Changing wildfire, changing forests: the effects of climate change on fire regimes and vegetation in the Pacific Northwest, USA. Fire Ecology 16(1): 4. DOI: 10.1186/s42408-019-0062-8

(2013) Stable Isotopes as Tracers of Anthropogenic Nitrogen Sources, Deposition, and Impacts. Elements 9(5): 339–344. DOI: 10.2113/gselements.9.5.339

, et al. (2020) Enhanced trace element mobilization by Earth’s ice sheets. Proceedings of the National Academy of Sciences 117(50). National Academy of Sciences: 31648–31659. DOI: 10.1073/pnas.2014378117

, et al. (2020) Landscape perception: linking physical monitoring data to perceived landscape properties. Landscape Research 45(2): 179–192. DOI: 10.1080/01426397.2019.1611751

, et al. (2010) The structure, biological activity and biogeochemistry of cryoconite aggregates upon an Arctic valley glacier: Longyearbreen, Svalbard. Journal of Glaciology 56(196): 349–362. DOI: 10.3189/002214310791968403

, et al. (2011) Anthropogenic and natural radionuclides in caribou and muskoxen in the Western Alaskan Arctic and marine fish in the Aleutian Islands in the first half of 2000s. Science of The Total Environment 409(19): 3638–3648. DOI: 10.1016/j.scitotenv.2011.06.044

68.

Houghton

(2001) The science of global warming. Interdisciplinary Science Reviews 26(4): 247–257. DOI: 10.1179/isr.2001.26.4.247

, et al. (2012) Nitrogen fluxes from the landscape are controlled by net anthropogenic nitrogen inputs and by climate. Frontiers in Ecology and the Environment 10(1): 37–43. DOI: 10.1890/100178 .

70.

Huang

Kang

, et al. (2019) Accumulation of Atmospheric Mercury in Glacier Cryoconite over Western China. Environmental Science & Technology 53(12): 6632–6639. DOI: 10.1021/acs.est.8b06575

(2003) Consequences and implication of heavy metal spatial variations in sediments of the Keelung River drainage basin, Taiwan. Chemosphere 53(9): 1113–1121. DOI: 10.1016/S0045-6535(03)00592-7

(1988) Chernobyl--the radiological impact on Canada. Canadian Association of Radiologists Journal = Journal l’Association Canadienne Des Radiologistes 39(1): 37–41.

73.

Huddart

Stott

(2020) Adventure Tourism in Alaska. In: Huddart

Stott

(eds) Adventure Tourism: Environmental Impacts and Management. Cham: Springer International Publishing, pp. 183–240. DOI: 10.1007/978-3-030-18623-4_7

(2015) Mobility and Bioavailability of Radionuclides in Soils. In: Walther

Gupta

(eds) Radionuclides in the Environment: Influence of Chemical Speciation and Plant Uptake on Radionuclide Migration. Cham: Springer International Publishing, pp. 37–59. DOI: 10.1007/978-3-319-22171-7_2

(2020) Climate Change Scenarios and Effects on Snow-Melt Runoff. Civil Engineering Journal 6: 1715–1725. DOI: 10.28991/cej-2020-03091577

76.

Jiang

Yin

, et al. (2019) Microplastic pollution in the rivers of the Tibet Plateau. Environmental Pollution 249: 91–98. DOI: 10.1016/j.envpol.2019.03.022

, et al. (2019) Linking atmospheric pollution to cryospheric change in the Third Pole region: current progress and future prospects. National Science Review 6(4): 796–809. DOI: 10.1093/nsr/nwz031

, et al. (2020) A review of black carbon in snow and ice and its impact on the cryosphere. Earth-Science Reviews 210: 103346. DOI: 10.1016/j.earscirev.2020.103346

, et al. (2020) Microplastics in sea ice and seawater beneath ice floes from the Arctic Ocean. Scientific Reports 10(1). 1. Nature Publishing Group: 5004. DOI: 10.1038/s41598-020-61948-6

, et al. (2020) Microplastic contamination in east Antarctic sea ice. Marine Pollution Bulletin 154: 111130. DOI: 10.1016/j.marpolbul.2020.111130

(2003) An Arctic Terrestrial Food-Chain Bioaccumulation Model for Persistent Organic Pollutants. Environmental Science & Technology 37(13). American Chemical Society: 2966–2974. DOI: 10.1021/es021035x

, et al. (2014) Increasing anthropogenic nitrogen in the North Pacific Ocean. Science 346(6213). American Association for the Advancement of Science: 1102–1106. DOI: 10.1126/science.1258396

, et al. (2016) Seasonal accumulation of persistent organic pollutants on a high altitude glacier in the Eastern Alps. Environmental Pollution 218: 804–812. DOI: 10.1016/j.envpol.2016.08.004

84.

Knap

(2012) The Long-Range Atmospheric Transport of Natural and Contaminant Substances. Springer Science & Business Media.

, et al. (2015) The role of atmospheric precipitation in introducing contaminants to the surface waters of the Fuglebekken catchment, Spitsbergen. Polar Research 34(1). Routledge: 24207. DOI: 10.3402/polar.v34.24207

, et al. (2006) Organochlorine Pesticide and Polychlorinated Biphenyl Concentrations in Snow, Snowmelt, and Runoff at Bow Lake, Alberta. Environmental Science & Technology 40(16): 4909–4915. DOI: 10.1021/es060237g

87.

Lawson

(1982) Mobilization, Movement and Deposition of Active Subaerial Sediment Flows, Matanuska Glacier, Alaska. The Journal of Geology 90(3, 279, 300). The University of Chicago Press: DOI: 10.1086/628680

88.

Bosch

Kang

, et al. (2016) Sources of black carbon to the Himalayan–Tibetan Plateau glaciers. Nature Communications 7. 12574, DOI: 10.1038/ncomms12574

89.

(2018) Moving Glaciers: Remaking Nature and Mineral Extraction in Chile. Latin American Perspectives 45(5): 102–119. DOI: 10.1177/0094582X17713757

90.

Kang

Wang

, et al. (2017) Composition and sources of polycyclic aromatic hydrocarbons in cryoconites of the Tibetan Plateau glaciers. Science of The Total Environment 574: 991–999. DOI: 10.1016/j.scitotenv.2016.09.159

91.

Liss

(2020) Microplastics: All up in the Air? 9684.

92.

Liu

Liang

, et al. (2019) Uncertainties in thermal-optical measurements of black carbon: Insights from source and ambient samples. Science of The Total Environment 656: 239–249. DOI: 10.1016/j.scitotenv.2018.11.353

, et al. (2015) Enhanced light absorption by mixed source black and brown carbon particles in UK winter. Nature Communications 6(1): 8435. DOI: 10.1038/ncomms9435

, et al. (2016) Accumulation of atmospheric radionuclides and heavy metals in cryoconite holes on an Arctic glacier. Chemosphere 160: 162–172. DOI: 10.1016/j.chemosphere.2016.06.051

, et al. (2018) The sources of high airborne radioactivity in cryoconite holes from the Caucasus (Georgia). Scientific Reports 8(1): 10802. DOI: 10.1038/s41598-018-29076-4

, et al. (2019) Airborne radionuclides and heavy metals in high Arctic terrestrial environment as the indicators of sources and transfers of contamination. The Cryosphere 13(7): 2075–2086. DOI: 10.5194/tc-13-2075-2019

, et al. (2021) Deposition of Plutonium Isotopes in Glacial Environments in the Northern and Southern Hemispheres. EGU21-8795, 3 March. Copernicus Meetings. DOI: 10.5194/egusphere-egu21-8795

, et al. (2018) Distinct Nitrogen Provisioning From Organic Amendments in Soil as Influenced by Farming System and Water Regime. Frontiers in Environmental Science 6. DOI: 10.3389/fenvs.2018.00040

99.

Zhang

Zhu

, et al. (2017) Simultaneous production of biocrude oil and recovery of nutrients and metals from human feces via hydrothermal liquefaction. Energy Conversion and Management 134: 340–346. DOI: 10.1016/j.enconman.2016.12.052

(2005) Recent climate change in the Arctic and its impact on contaminant pathways and interpretation of temporal trend data. Science of The Total Environment 342(1): 5, 86. Sources, Occurrence, Trends and Pathways of Contaminants in the Arctic: 5–86. DOI: 10.1016/j.scitotenv.2004.12.059

101.

MacDonell

Fitzsimons

(2008) The formation and hydrological significance of cryoconite holes. Progress in Physical Geography: Earth and Environment 32(6): 595–610. DOI: 10.1177/0309133308101382

102.

Macdonell

Fitzsimons

(2012) Observations of cryoconite hole system processes on an Antarctic glacier. Revista chilena de historia natural 85(4): 393–407. DOI: 10.4067/S0716-078X2012000400003

, et al. (2019) Amazonian Biomass Burning Enhances Tropical Andean Glaciers Melting. Scientific Reports 9(1): 16914. DOI: 10.1038/s41598-019-53284-1

, et al. (2010) Fate of soil-applied black carbon: downward migration, leaching and soil respiration. Global Change Biology 16(4): 1366–1379. DOI: 10.1111/j.1365-2486.2009.02044.x .

(2012) Atmospheric releases during the 2003 glacier wildfires: mapping, analysis and modeling. In: 2012 IEEE International Geoscience and Remote Sensing Symposium, Carbondale, IL, pp. 5360–5363. DOI: 10.1109/IGARSS.2012.6352396

, et al. (2020) Controls over particle motion and resting times of coarse bed load transport in a glacier-fed mountain stream. Journal of Geophysical Research: Earth Surface 125(4): e2019JF005253. DOI: 10.1029/2019JF005253

(2002) Characterization of heterotrophic microorganisms in alpine glacier cryoconite. Arctic, Antarctic, and Alpine Research 34(1): 88–93. DOI: 10.1080/15230430.2002.12003472

108.

McIntyre

(2007) Water Quality Analysis of the North Palisade Glacier Sierra Nevada Mountians, Pomona, CA. Cal Poly Pomona University.

, et al. (2016) The nitrogen legacy: emerging evidence of nitrogen accumulation in anthropogenic landscapes. Environmental Research Letters 11(3): 035014. DOI: 10.1088/1748-9326/11/3/035014

110.

Meyer

Wania

(2008) Organic contaminant amplification during snowmelt. Water Research 42(8): 1847–1865. DOI: 10.1016/j.watres.2007.12.016

(2006) Measuring the release of organic contaminants from melting snow under controlled conditions. Environmental Science & Technology 40(10): 3320–3326. DOI: 10.1021/es060049q

, et al. (2018) Rate of sediment accumulation and historic metal contamination in a tidewater glacier fjord, Svalbard. Marine Pollution Bulletin 131: 453–459. DOI: 10.1016/j.marpolbul.2018.04.057

, et al. (2016) Historic records of organic compounds from a high Alpine glacier: influences of biomass burning, anthropogenic emissions, and dust transport. Atmospheric Chemistry and Physics 16(2): 1029–1043. DOI: 10.5194/acp-16-1029-2016 .

, et al. (2020) Reaching new heights in plastic pollution—preliminary findings of microplastics on mount everest. One Earth 3(5): 621–630. DOI: 10.1016/j.oneear.2020.10.020

115.

Natural Resources Defence Council (2014) Dumping Dirty Diesels in Latin America: Reducing Black Carbon and Air Pollution from Diesel Engines in Latin American Countries. New York, NY: Natural Resources Defence Council

, et al. (2018) Investigating microplastic trophic transfer in marine top predators. Environmental Pollution 238: 999–1007. DOI: 10.1016/j.envpol.2018.02.016

, et al. (2014) Global warming releases microplastic legacy frozen in Arctic Sea ice. Earth’s Future 2(6): 315–320. DOI: 10.1002/2014EF000240 .

, et al. (2015) Marine microplastic-associated biofilms – a review. Environmental Chemistry 12(5): 551–562. DOI: 10.1071/EN15069

, et al. (2011) Nitrogen turnover in soil and global change. FEMS Microbiology Ecology 78(1): 3–16. DOI: 10.1111/j.1574-6941.2011.01165.x

, et al. (2020) Radionuclides from the Fukushima Daiichi Nuclear Power Plant in terrestrial systems. Nature Reviews Earth & Environment 1(12): 644–660. DOI: 10.1038/s43017-020-0099-x

(2019) Extreme levels of fallout radionuclides and other contaminants in glacial sediment (cryoconite) and implications for downstream aquatic ecosystems. Scientific Reports 9(1): 12531. DOI: 10.1038/s41598-019-48873-z

, et al. (2021) Black carbon over a central Himalayan Glacier (Satopanth): Pathways and direct radiative impacts. Science of The Total Environment 766: 144242. DOI: 10.1016/j.scitotenv.2020.144242

, et al. (2021) Macroplastics contamination on glaciers from Italian Central-Western Alps. Environmental Advances 5: 100084. DOI: 10.1016/j.envadv.2021.100084

, et al. (2018) Arctic sea ice is an important temporal sink and means of transport for microplastic. Nature Communications 9(1): 1505. DOI: 10.1038/s41467-018-03825-5

, et al. (2001) A mean net accumulation pattern derived from radioactive layers and radar soundings on Austfonna, Nordaustlandet, Svalbard. Journal of Glaciology 47(159): 555–566. DOI: 10.3189/172756501781831800

, et al. (2018) Post-depositional biodegradation processes of pollutants on glacier surfaces. Condensed Matter 3(3): 24. DOI: 10.3390/condmat3030024

, et al. (2021) Snowpack-stored atmospheric surface-active contaminants traced with snowmelt water surface film rheology. Environmental Science and Pollution Research 28(5): 5443–5454. DOI: 10.1007/s11356-020-10874-1

128.

Poniecka

Bagshaw

(2021) The Cryoconite Biome. De Gruyter. 11 Available at: https://www.degruyter.com/document/doi/10.1515/9783110497083-011/html (accessed 8 June 2021).

129.

Poniecka

Bagshaw

Sass

, et al. (2020) Physiological capabilities of cryoconite hole microorganisms. Frontiers in Microbiology 11: 1783. DOI: 10.3389/fmicb.2020.01783

130.

Port of London Authorities (2021) Canadian Sediment Quality Guidelines for the Protection of Aquatic Life. Available at: http://www.pla.co.uk/Environment/Canadian-Sediment-Quality-Guidelines-for-the-Protection-of-Aquatic-Life (accessed 8 June 2021).

131.

Rizzi

Finizio

Maggi

, et al. (2019) Spatial-temporal analysis and risk characterisation of pesticides in Alpine glacial streams. Environmental Pollution 248: 659–666. DOI: 10.1016/j.envpol.2019.02.067

132.

Rowe

Cordero

Warren

, et al. (2019) Black carbon and other light-absorbing impurities in snow in the Chilean Andes. Scientific Reports 9(1): 1. DOI: 10.1038/s41598-019-39312-0

133.

Saavedra

Cortés

Viale

, et al. (2020) Atmospheric rivers contribution to the snow accumulation over the southern andes (26.5° S–37.5° S). Frontiers in Earth Science 8: 1–11. Available at: https://www.frontiersin.org/article/10.3389/feart.2020.00261 (accessed 27 January 2022).

134.

Santofimia

López-Pamo

Palomino

, et al. (2017) Acid rock drainage in Nevado Pastoruri glacier area (Huascarán National Park, Perú): hydrochemical and mineralogical characterization and associated environmental implications. Environmental Science and Pollution Research 24(32): 25243–25259. DOI: 10.1007/s11356-017-0093-0

135.

Santolaria

Arruebo

Pardo

, et al. (2015) Evaluation of airborne organic pollutants in a pyrenean glacial lake (the sabocos tarn). Water, Air, & Soil Pollution 226(11): 383. DOI: 10.1007/s11270-015-2648-3

136.

Santra

Verma

Fujita

, et al. (2019) Simulations of black carbon (BC) aerosol impact over Hindu Kush Himalayan sites: validation, sources, and implications on glacier runoff. Atmospheric Chemistry and Physics 19(4): 2441–2460. DOI: 10.5194/acp-19-2441-2019.

, et al. (2018) Microbial communities and their potential for degradation of dissolved organic carbon in cryoconite hole environments of Himalaya and Antarctica. Microbiological Research 208: 32–42. DOI: 10.1016/j.micres.2018.01.004

(2014) Migrations and dynamics of the intertropical convergence zone. Nature 513(7516): 45–53. DOI: 10.1038/nature13636

, et al. (2020) Rapid worldwide growth of glacial lakes since 1990. Nature Climate Change 10(10): 939–945. DOI: 10.1038/s41558-020-0855-4

, et al. (2007) Microorganisms and migration of radionuclides in environment. Comptes Rendus Chimie 10(10): 1092–1107. DOI: 10.1016/j.crci.2007.02.010

, et al. (2019) Drivers of mercury cycling in the rapidly changing glacierized watershed of the high arctic’s largest lake by volume (Lake Hazen, Nunavut, Canada). Environmental Science & Technology 53(3): 1175–1185. DOI: 10.1021/acs.est.8b05926

(2021) Quantifying meltwater sources and contaminant fluxes from the athabasca glacier, canada. ACS Earth and Space Chemistry 5(1): 23–32. DOI: 10.1021/acsearthspacechem.0c00256

, et al. (2021) Microplastics in Glaciers: First Results from the Vatnajökull Ice Cap. Sustainability 13(8): 4183. DOI: 10.3390/su13084183

, et al. (2014) Where does the optically detectable aerosol in the European Arctic come from? Tellus B: Chemical and Physical Meteorology 66(1): 21450. DOI: 10.3402/tellusb.v66.21450

145.

Stohl

(2006) Characteristics of atmospheric transport into the Arctic troposphere. Journal of Geophysical Research: Atmospheres 111(D11): D11306. DOI: 10.1029/2005JD006888 .

, et al. (2007) Arctic smoke – record high air pollution levels in the European Arctic due to agricultural fires in Eastern Europe in spring 2006. Atmospheric Chemistry and Physics 7(2): 511–534. DOI: 10.5194/acp-7-511-2007

, et al. (2009) Influence of particle chemical composition on the phase of cold clouds at a high-alpine site in Switzerland. Journal of Geophysical Research: Atmospheres 114(D18): D18206. DOI: 10.1029/2008JD011365 .

, et al. (2012) Heavy metals toxicity and the environment. EXS 101: 133–164. DOI: 10.1007/978-3-7643-8340-4_6

, et al. (2009) Accumulation of anthropogenic radionuclides in cryoconites on Alpine glaciers. Journal of Environmental Radioactivity 100(7): 590–598. DOI: 10.1016/j.jenvrad.2009.04.008

, et al. (2007) Arctic smoke – aerosol characteristics during a record smoke event in the European Arctic and its radiative impact. Atmospheric Chemistry and Physics 7(11): 3035–3053. DOI: 10.5194/acp-7-3035-2007

151.

UNEP (2017) Stockholm Convention on Persistent Organic Pollutants (POPs): Texts and Annexes. Nairobi: UNEP

(2019) Integrated impacts of climate change on glacier tourism. Advances in Climate Change Research 10(2), 71–79. Special issue on cryospheric functions and services: 71–79. DOI: 10.1016/j.accre.2019.06.006

, et al. (2006) Gradient distribution of persistent organic contaminants along northern slope of central-Himalayas, China. Science of The Total Environment 372(1): 193–202. DOI: 10.1016/j.scitotenv.2006.09.008

154.

Wang

Zhu

, et al. (2019) Persistent organic pollutants in the polar regions and the Tibetan Plateau: a review of current knowledge and future prospects. Environmental Pollution 248: 191–208. DOI: 10.1016/j.envpol.2019.01.093

, et al. (2012) Correlations of trace element levels in the diet, blood, urine, and feces in the Chinese male. Biological Trace Element Research 145(2): 127–135. DOI: 10.1007/s12011-011-9177-8

, et al. (2018) Constraining aging processes of black carbon in the community atmosphere model using environmental chamber measurements. Journal of Advances in Modeling Earth Systems 10(10): 2514–2526. DOI: 10.1029/2018MS001387 .

157.

Wania

Mackay

(1993) Global fractionation and cold condensation of low volatility organochlorine compounds in polar regions. Ambio 22(1): 10–18.

(2015) Glacier tourism: a scoping review. Tourism Geographies 17(5), 635–662. DOI: 10.1080/14616688.2015.1084529

159.

WHO (2008) Guidelines for Drinking-Water Quality. 3rd etition. Geneva: WHO. Available at: https://www.who.int/water_sanitation_health/dwq/fulltext.pdf (accessed 8 June 2021).

160.

Wiedensohler

Andrade

Weinhold

, et al. (2018) Black carbon emission and transport mechanisms to the free troposphere at the La Paz/El Alto (Bolivia) metropolitan area based on the Day of Census (2012). Atmospheric Environment 194: 158–169. DOI: 10.1016/j.atmosenv.2018.09.032

161.

Williams

Lund

Johnson

, et al. (1998) Natural and anthropogenic nitrate contamination of groundwater in a rural community, california. Environmental Science & Technology 32(1): 32–39. DOI: 10.1021/es970393a

162.

Williams

(2014) Peru’s Media-Friendly Mining Ban Conceals Toxic Inaction. NACLA Report on the Americas 47(4): 58–63. DOI: 10.1080/10714839.2014.11721817

163.

Wright

Young

Bamber

, et al. (2014) Subglacial hydrological connectivity within the Byrd Glacier catchment, East Antarctica. Journal of Glaciology 60(220): 345–352. DOI: 10.3189/2014JoG13J014

164.

Y-L

Davidson

Dolske

, et al. (1992) Dry deposition of atmospheric contaminants: the relative importance of aerodynamic, boundary layer, and surface resistances. Aerosol Science and Technology 16(1). Taylor & Francis: 65–81. DOI: 10.1080/02786829208959538

165.

Yang

Tian

Friedrichs

MAM

, et al. (2015) Increased nitrogen export from eastern North America to the Atlantic Ocean due to climatic and anthropogenic changes during 1901–2008. Journal of Geophysical Research: Biogeosciences 120(6): 1046–1068. DOI: 10.1002/2014JG002763.

, et al. (2021) Natural acid rock drainage in alpine catchments: a side effect of climate warming. Science of The Total Environment 778: 146070. DOI: 10.1016/j.scitotenv.2021.146070

(2019) Modelling the future evolution of glaciers in the European Alps under the EURO-CORDEX RCM ensemble. The Cryosphere 13(4): 1125–1146. DOI: 10.5194/tc-13-1125-2019 .

168.

Zettler