Interior Secretary David Bernhardt is being investigated for calendar discrepancies
From Politico: “[A letter from the National Archives and Records Administration to the Interior Department] adds new pressure to a department that is facing investigations by House Democrats who question whether Bernhardt has violated federal record-keeping laws. Bernhardt’s existing daily schedule shows that the former fossil fuel and agriculture lobbyist has met with representatives of former clients who stood to gain from Interior’s decisions, but the department has released few details about his activities during about one-third of his days in office.”
Read more about the new Secretary of the Interior and a federal proposal to raise the height of Shasta Dam in California on GlacierHub.
Mercury concentrations at Mt. Yulong on the Tibetan Plateau
From Environmental Science and Pollution Research: “For the first time, Hg was studied over the Mt. Yulong region, in the various matrices of the environment including, surface snow/ice, snowpit, and meltwater… It was evident of the presence of an anthropogenic source of pollutants that have been long-range transported to Yulong Mountain… Suggesting that the concentration of Hg depends [more] on the distance from the anthropogenic sources than the different characteristics of the water bodies.”
Read more about mercury contamination from glacial rivers in High Arctic watersheds on GlacierHub.
Yak herders of the Himalayas voice their concerns
From ICIMOD: “For the first time in the history of the annual International Yak Conference, yak herders from the southern side of the Himalaya were able to join their counterparts from other parts of Asia to raise their concerns… Given the challenges facing yak herding, there is much to be gained from knowledge sharing across borders… Sharing such knowledge and technology from plateaus to other yak-rearing countries will contribute to sustainable yak farming in the region.”
Read more on GlacierHub about yak herders in Bhutan and what they have to say about global warming.
In this week’s Roundup, read about lichen colonization on Svalbard’s glaciers, mercury inputs from glacial rivers in High Arctic Canada, and the impact of both climate change and globalization on a small village in the Indian Himalayas.
Lichen Colonization on Svalbard’s Glaciers
From Acta Societatis Botanicorum Poloniae: “The high number of lichen species that were new to Svalbard indicates the need for further research on the biodiversity of lichens in the Arctic. In particular, the glacier forelands deserve attention if further warming of the climate continues, as species sensitive to competition from vascular plants will move into habitats in the vicinity of glaciers.”
From Environmental Science & Technology: “Glacial rivers were the most important source of MeHg and THg to Lake Hazen, accounting for up to 53% and 94% of the inputs, respectively. However, due to the MeHg and THg being primarily particle-bound, Lake Hazen was an annual MeHg and THg sink…This study highlights the potential for increases in mercury inputs to arctic ecosystems downstream of glaciers despite recent reductions in global mercury emissions.”
For more detail, click here to read GlacierHub’s recent post regarding this study.
“Double Exposure” in Indian Himalayan Communities
From Environmental Science & Policy: “This study uses a living with approach to explore how change and development was experienced by a small agricultural community in the Indian Himalayas. The findings reveal ‘double exposure’ to an increasingly deficient water supply, and aspects of globalisation.”
Mercury is a contaminant which poses environmental health risks to terrestrial and aquatic ecosystems around the world, especially in the Arctic. A recent study in Environmental Science & Technology traces the source of mercury concentrations in Lake Hazen to increased flow in glacial rivers. Lake Hazen, located in Nunavut, Canada, is the High Arctic’s largest lake by volume, and reaches depths up to 267m.
There are both natural and anthropogenic sources of mercury. Global mercury emissions have been declining, specifically after ratification of the Minamata Convention. However, as anthropogenic sources decrease, climate change could be increasing natural sources of mercury—if in a less direct fashion than emissions.
Mercury is stored in permafrost and glacial ice, so as permafrost thaws and ice melts, downstream ecosystems could be impacted. Microbes can also transform mercury into a poisonous neurotoxin called methylmercury, which impacts the nervous system. Both can bioaccumulate in organisms, especially at higher levels of the food chain.
“The primary focus of the research program at Lake Hazen is on understanding the biogeochemistry of freshwater ecosystems downstream of the glaciers of the Northern Ellesmere Icefield,” said Kyra St. Pierre, the study’s lead author, in an interview with GlacierHub. St. Pierre, who conducted this research as a part of the Department of Biological Sciences at the University of Alberta, Canada, went on to say that the study aimed to explain how recent warming patterns might impact biogeochemical cycles in the future.
Lake Hazen receives meltwater—and up to 94 percent of total mercury inputs—primarily from three glacial rivers. The study showed that most mercury from these rivers flowed into the lake in particulate form. This means that the particles carrying mercury are not dissolved, making the water flowing into Lake Hazen more turbid, or cloudy, than the lake’s existing water. Due to the weight of the particles it carries, turbid water is also very dense. The increased weight creates what is called a turbidity current, which efficiently deposits most of the mercury particles in the bottom of the lake.
St. Pierre named these turbidity currents the study’s most surprising result, because it revealed important aspects of how Lake Hazen’s watershed functions. “Not only do [turbidity currents] transport mercury from the surface but also oxygen and other nutrients directly to the depths of the lake,” she said.
This study is distinctive in that it approached mercury cycling at a watershed-scale instead of looking at individual system components. St. Pierre called this one of the study’s most important attributes, explaining that if, for example, they had decided to focus simply on Lake Hazen’s outflows, they would have concluded that mercury concentrations were extremely low.
Lake Hazen’s turbidity currents make it a huge mercury sink. Despite huge mercury inputs from glacial rivers, the lake’s main outflow, the Ruggles River, discharges relatively small amounts of mercury and methylmercury. The researchers found that the lake sequestered over 95 percent of total mercury inputs to the system annually. Downstream in the Ruggles River, mercury concentrations rose exponentially, a result of erosion and thawing permafrost.
The High Arctic is extremely sensitive to increasing temperatures and precipitation in the context of anthropogenic climate change. Craig Emmerton and Jennifer Graydon, researchers at the University of Alberta, spoke to GlacierHub about some of the larger implications of this study. “The High Arctic is among the most rapidly changing regions on Earth and its climate is expected to become warmer and wetter,” they said, pointing out the potential role of glaciers and permafrost as developing sources of mercury with the power to contaminate freshwater and marine ecosystems.
“I think we can safely infer that as warming continues in High Arctic latitudes, we can expect a greater delivery of mercury from the cryosphere to downstream ecosystems,” said St. Pierre. Though Lake Hazen retains most mercury inputs from glacial rivers, the researchers found a 3.4-times greater water volume and 2-times higher delivery of total mercury in the notably warm summer of 2015, than in the much cooler summer of 2016. So, as glaciers continue to melt, more mercury will inevitably make its way downstream.
Lake Hazen’s depth and size draw close similarities to High Arctic fjord systems. The researchers showed that these turbidity currents also occur in fjords indirectly fed by land-terminating glaciers. Almost 70 percent of arctic glaciers are land-terminating glaciers, and so could be important sources of mercury for marine ecosystems. More, fjords fed by marine-terminating glaciers can flow directly into high productivity zones, increasing potential for bioaccumulation in organisms and into coastal food webs.
Ultimately, this study highlights an important discovery—even with reduction of direct anthropogenic sources of mercury, there is a lingering, growing anthropogenic driver—climate change.
Mercury Deposited as Snowfall Incorporated into Meltwater
From the Journal of Environmental Sciences: “The Tibetan Plateau (TP) is recognized as the ‘Water Tower of Asia.’ Yet our understanding of mechanisms influencing incorporation of mercury (Hg) into freshwater in mountain glaciers on the TP remains quite limited. Extensive sampling of environmental matrices (e.g., snow/ice) were conducted on the East Rongbuk glacier on Mt. Everest and Zhadang glacier on Mt. Nyainqentanglha for Hg speciation analysis. Speciated Hg behaved quite different during snowmelt: a preferential early release of DHg (dissolved Hg) was observed at the onset of snowmelt, whereas PHg (particulate-bound Hg) and THg (total Hg) become relatively enriched in snow and released later.”
Fish Diversity in Himalayan Streams Varies in Glacial and Rain-fed Streams
From Environmental Biology of Fishes: “Assessment of headwater biodiversity is essential for maintaining upstream downstream ecosystem services of rivers. Fish biodiversity assessment was conducted in the headwater tributaries of the glacial-fed Tamor River and rain-fed Kamala River in eastern Nepal. A total of eight sites were sampled… A total of 8940 fishes belonging to four orders, 10 families, 26 genera and 34 species were enumerated. Significant variation in Shannon-Weiner Diversity Index (p = 0.015) and Species Richness (p = 0.005) between the glacial fed and rain fed streams with higher values of these indices in the rain fed tributaries… These findings indicate that fish assemblages reflect the different ecological regimes of the glacial-fed and rain-fed headwaters.”
Glacial Areas in Colombia Have Fewer Black Flies
From Acta Tropica: “Vector ecology is a key factor in understanding the transmission of disease agents, with each species having an optimal range of environmental requirements. Scarce data, however, are available for how interactions of local and broad-scale climate phenomena, such as seasonality and the El Niño Southern Oscillation (ENSO), affect simuliids. We, therefore, conducted an exploratory study to examine distribution patterns of species of Simuliidae along an elevational gradient of the Otún River in the Colombian Andes, encompassing four ecoregions… Species richness and occurrence in each ecoregion were influenced by elevation, seasonality, and primarily the warm El Niño and cool La Niña phases of the ENSO.”
Mercury contamination has long been a threat to animal carnivores and human residents in the Arctic. Mercury exports from river basins to the ocean form a significant component of the Arctic mercury cycle, and are consequently of importance in understanding and addressing this contamination. Jens Søndergaard of the Arctic Research Centre of Aarhus University, Denmark and his colleagues have been conducting research on this topic in Greenland for a number of years. They published results of their work in the journal Science of the Total Environment in February 2015. Søndergaard and his colleagues assessed the mercury concentrations in and exports from the Zackenberg River Basin in northeast Greenland for the period 2009 – 2013. This basin is about 514 square kilometers in area, of which 106 square kilometers are covered by glaciers. Glacial outburst floods have been regularly observed in Zackenberg River since 1996. This study hypothesized that the frequency, magnitude, and timing of the glacial outburst floods and associated meteorological conditions would significantly influence the riverine mercury budget. Indeed, they found significant variation from year to year, reflecting weather and floods. The total annual mercury release varied from 0.71 kg to over 1.57 kg. These are significant amounts of such a highly toxic substance.
Søndergaard and his colleagues found that sediment-bound mercury contributed more to total releases than mercury that was dissolved in the river. Initial snowmelt, sudden erosion events, and glacial lake outburst floods all influenced daily riverine mercury exports from Zackenberg River Basin during the summer, the major period of river flow. The glacial lake outburst floods were responsible for about 31 percent of the total annual riverine mercury release. Summer temperatures and the amount of snowfall from the previous winter also played important roles in affecting the annual levels of mercury release. The authors note that releases are likely to increase, because global warming is contributing to greater levels of permafrost thawing in the region; this process, in turn, destabilizes river banks, allowing mercury contained in them to be discharged into rivers.
Mercury produces adverse health effects even at low levels. It is commonly known that mercury is toxic to the nervous system. According to the U.S. Environmental Protection Agency (EPA), consuming mercury-contaminated fish accounts for the primary route of exposure for most human populations. Mercury can also threaten the health of the seabirds and marine mammals which consume fish—and which Greenlandic populations. The release of riverine mercury in Zackenberg might not have strong influence in this remote region of northeast Greenland, far from human settlements and with few fisheries to date. However, the total yearly released mercury from all the river basins in Greenland is more significant, and is growing. There is a significant risk of transport in marine ecosystems through food chains, causing mercury poisoning among humans and wildlife in Greenland and in adjacent coastal countries.