Mercury Accumulation In Sediments Research Articles

Effect of environmental variables on mercury accumulation in sediments of an anthropogenically impacted tropical estuary (Buenaventura Bay, Colombian Pacific)

Estuaries are the main entry areas of mercury to the marine environment and are important to understand the effect of this contaminant on marine organisms, since it accumulates in the sediments becoming available to enter the food trophic chain. This study aims to determine the environmental variables that mainly influence the spatiotemporal dynamics of total mercury accumulation in sediments of tropical estuaries. Sediment samples were collected from interior and exterior areas of the estuary during the dry and rainy seasons, representing the spatiotemporal gradients of the estuary. The grain size, organic matter content (OM), and total mercury concentration (THg) of the sediment samples were determined. In addition, salinity, temperature, dissolved oxygen, and pH of the water column associated with each sediment sample were assessed. The variations in environmental conditions, OM and THg in sediment were in accordance with a gradient which goes from conditions influenced by fresh water in the inner estuary to conditions influenced by sea water in the outer part of the estuary. The OM and THg in sediments presented similar variation patterns; they were higher in the rainy season than in the dry season and in the interior area of the estuary than in the exterior area. Despite the complex dynamic observed in the distribution and accumulation processes of mercury in sediments, these processes could be modeled from OM and salinity parameters. Due to the correlations found, in the process of accumulation of mercury in sediments the OM could represents the pathway of transport and accumulation of THg, and salinity could represent the influence of the hydroclimatic variations and environmental gradients of the estuary.

Mercury accumulation in sediments of Lhù’ààn Mânʼ (Kluane Lake, YT): Response to past hydrological change

ABSTRACT Northern lakes provide many ecosystem services, including the provision of traditional foods and clean water. These systems are vulnerable to climate-driven changes in hydrology and contaminant accumulation, but the direction and magnitude of projected changes are poorly constrained. One contaminant of concern is mercury; currently, we cannot accurately predict how mercury accumulation in lakes will respond to climate-induced changes, especially in lakes with glacial inflows and complex hydrology. Sediment cores collected from two regions of a glacially fed lake (Lhù’ààn Mân’; Kluane Lake, Yukon, Canada) were analyzed to investigate controls on sediment mercury accumulation in the context of previously described hydrological changes. Differences in catchment contributions drove differences in sediment mercury accumulation between lake regions during the Duke River hydrological period (ca. 750–1650). During the more recent Slims River hydrological period (ca. 1650–2015), mercury accumulation did not differ between regions, and mercury was delivered to the lake primarily via catchment organic matter and carbonate-rich sediments from the largest, glacially derived inflow (Slims River). Recent climate-induced geomorphic change caused loss of the main lake inflow (Slims River) in 2016, making Kluane Lake an ideal system for future investigations of how loss of glacial inflow will affect mercury accumulation in northern lakes.

Correction to: Patterns and controls of mercury accumulation in sediments from three thermokarst lakes on the Arctic Coastal Plain of Alaska

In the original publication, the incorrect GIS map projection was used to calculate lake surface areas and catchment areas that were presented

Correction to: Patterns and controls of mercury accumulation in sediments from three thermokarst lakes on the Arctic Coastal Plain of Alaska

In the original publication, the incorrect GIS map projection was used to calculate lake surface areas and catchment areas that were presented

Patterns and controls of mercury accumulation in sediments from three thermokarst lakes on the Arctic Coastal Plain of Alaska

The biogeochemical cycle of mercury will be influenced by climate change, particularly at higher latitudes. Investigations of historical mercury accumulation in lake sediments inform future predictions as to how climate change might affect mercury biogeochemistry; however, in regions with a paucity of data, such as the thermokarst-rich Arctic Coastal Plain of Alaska (ACP), the trajectory of mercury accumulation in lake sediments is particularly uncertain. Sediment cores from three thermokarst lakes on the ACP were analyzed to understand changes in, and drivers of, Hg accumulation over the past ~ 100 years. Mercury accumulation in two of the three lakes was variable and high over the past century (91.96 and 78.6 µg/m2/year), and largely controlled by sedimentation rate. Mercury accumulation in the third lake was lower (14.2 µg/m2/year), more temporally uniform, and was more strongly related to sediment Hg concentration than sedimentation rate. Sediment mercury concentrations were quantitatively related to measures of sediment composition and VRS-inferred chlorophyll a, and sedimentation rates were related to various catchment characteristics. These results were compared to data from 37 previously studied Arctic and Alaskan lakes. Results from the meta-analysis indicate that thermokarst lakes have significantly higher and more variable Hg accumulation rates than non-thermokarst lakes, suggesting that certain properties (e.g., thermal erosion, thaw slumping, low hydraulic conductivity) likely make lakes prone to high and variable Hg accumulation rates. Differences and high variability in Hg accumulation among high latitude lakes highlight the complexity of predicting future climate-related change impacts on mercury cycling in these environments.

Solar irradiance and primary productivity controlled mercury accumulation in sediments of a remote lake in the Southern Hemisphere during the past 4000 years

AbstractMercury (Hg) is a toxic trace element known to highly accumulate in aquatic biota and uptake by algae is the main entry‐point into the aquatic food chain. However, the effect of changes in solar irradiance and climatic conditions on Hg uptake by algae is largely unknown. We analyzed the link between sediment Hg accumulation, cyclic changes in total solar irradiance (TSI), and related changes in lake productivity as well as climate during the past 4.5 thousand years (kyr) in sediments of a small highly productive lake in Southern Patagonia (53°S). The analyses encompass proxies for TSI (based on 10Be), sediment geochemical composition, and lake productivity (FTIR spectra, and hydrogen‐index). The sediment record shows high concentrations of organic matter (median 70%) and strong variations in Hg accumulation rates (14–53 μg m2 yr−1) which correspond to changes in aquatic productivity and TSI. Accumulation of Hg was highest during dryer periods when irradiance and lake productivity was high. During these periods, accumulation was up to fourfold higher compared to those of lower TSI, lower productivity, and wetter climatic conditions. Higher amounts of algae biomass can increase Hg scavenging by organic particles and Hg export to the sediment. To obtain mass balance, we assume that the increase in sediment Hg accumulation rates during periods of lower Hg fluxes from the catchment (drier) caused a decrease in water phase Hg and in rates of Hg evasion from the lake.

Mercury accumulation in sediments and seabird feathers from the Antarctic Peninsula

In an effort to assess the impact of mercury in the Antarctic Peninsula, we conducted ecotoxicological research in this region during the summer of 2012 and 2013. The objectives were to assess: (a) mercury levels in sediment samples; (b) mercury accumulation in Antarctic seabird feathers: Catharacta lonnbergi (brown skua), Pygoscelis papua (gentoo penguin) and Pygoscelis antarctica (chinstrap penguin); and (c) biomagnification (BMF predator/prey) and biota sediment accumulation (BSAF skuas/sediment) factors. Mercury concentrations in sediment were relatively low. Mercury concentrations were significantly higher in brown skuas and gentoo penguins than in chinstrap penguins (2012), and significantly higher in brown skuas than in both penguins (2013). BMF indicated 2–7.5 times greater mercury levels in brown skuas than in penguins. BSAF values suggested an apparent temporal decrease of 18.2% of this ratio from 2012 to 2013. Long-range environmental transport is the likely route of entry of mercury into the Antarctic Peninsula.

A 17,300-year record of mercury accumulation in a pristine lake in southern Chile

Anthropogenic mercury accumulation in lake sediments has been studied extensively, but natural processes that controlled mercury accumulation in the past are still poorly understood. We present a 17,300-year record of mercury accumulation in the sediments of Lake Hambre, southernmost Patagonia, Chile (53°S, 70°W), in combination with an investigation of environmental changes in the region. Mercury accumulation in the remote pristine lake varied appreciably, as much as 16×, exceeding the anthropogenic forcing of atmospheric mercury fluxes by a factor of 3–5. Principal Component Analysis revealed that short-term variations were not related to changes in atmospheric mercury deposition or to fluxes of mineral soil into the lake. Instead, there was significant covariation between short-term changes in mercury and catchment-derived trace elements, e.g. copper and yttrium, throughout the past 17,000 years. Covariation between mercury and carbon concentration in some parts of the record suggests that fluxes of particulate and dissolved organic matter from the catchment to the lake account for short-term variations in mercury accumulation. Nevertheless, over the long term, there is no common trend for mercury accumulation and organic matter flux. The median mercury accumulation rate was rather constant (29 μg m−2 a−1), whereas the flux of terrestrial organic matter into the lake increased through time. We hypothesize that this was a consequence of a progressive decrease in the input of terrestrial organic matter-bound mercury through time. Whereas production of terrestrial organic matter increased over the long term because of development of catchment vegetation and soils, following glacier retreat, amounts of mercury, copper and yttrium provided by atmospheric deposition and bedrock weathering remained relatively constant. As a consequence, despite increased fluxes of terrestrial organic matter to the lake, fluxes of mercury remained constant.

Effect of pH, Sulphate Concentration and Total Organic Carbon on Mercury Accumulation in Sediments in the Volta Lake at Yeji, Ghana

In this study, pH, total organic carbon, sulphate concentration and mercury concentrations of sediment samples from the Volta Lake at Yeji in the northern part of Ghana were determined. The results indicate that pH ranged from 6.32 to 8.21, total organic carbon ranged from 0.17 to 3.02 g/kg and sulphate concentration from 10.00 to 57.51 mg/kg. Total mercury concentrations ranged from 32.61 to 700 ng/g which is below the International Atomic Energy Agency recommended value of 810 ng/g. Humic substance-bound mercury ranged from 81.15 to 481.31 mg/kg in sediments and its two fractions existed as humic acid-bound mercury > fulvic acid-bound mercury with the ratio of humic substance-bound mercury to fulvic acid-bound mercury as 1.62 on the average. Humic substance-bound mercury and the two fractions fulvic acid-bound mercury and humic substance-bound mercury in sediments were favorably determined and found to correlate significantly positive with total organic carbon (r = 0.538) and total mercury (r = 0.574). However, there were poor correlations between SO(4) (2-) concentrations and humic substance-bound mercury (r = -0.391) as well as the two fractions; fulvic acid (r = -0.406) and humic acid (r = -0.381). By assuming that methyl mercury is mostly formed in sediments, these significant relations suggest that the efficiency of mercury being methylated from a given inorganic form depends on the amount, and most likely biochemical composition of total organic carbon in the lake sediment but not the SO(4) (2-) concentration.

Distribution and Accumulation of Mercury in Sediments of Kaohsiung River Mouth, Taiwan

This study was conducted using the data collected in May 2009 to investigate and analyze mercury (Hg) contained in the surface sediments, and to evaluate the accumulation of Hg and the degree of its potential risk. The results show that samples collected at all monitoring stations near the mouth of Kaohsiung River contain 0.15–1.15mg kg-1of Hg with average of 0.68±0.30mg kg-1. The spatial distribution of Hg reveals that the Hg concentration is relatively high in the river mouth region, and gradually diminishes toward the harbor region. This indicates that upstream industrial and municipal wastewater discharges along the river bank are major sources of pollution. The accumulation factor and potential ecological risk index indicate that the sedimentation at Kaohsiung River mouth has the most serious degree of Hg accumulation and the highest ecological potential risk. Therefore, a strategy for effective controlling and managing Kaohsiung River upstream pollution needs to be immediately implemented in order to improve the sediment quality and alleviate the ecological risk.

Freshwater Fish Mercury Concentrations in a Regionally High Mercury Deposition Area

We sampled and analyzed individually, edible dorsal muscle from largemouth bass (LMB), Micropterus salmoides (n=138) and yellow perch (YP), Perca flavescens (n=97) from 15 lakes to investigate potential local impacts of mercury emis- sion point sources in northeastern Massachusetts (MA), USA. This area was identified in three separate modeling exercises as a mercury deposition hotspot. In 1995, 55% of mercury emissions to the environ- ment from all MA sources came from three municipal solid waste combustors (trash incinerators) and one large regional medical waste incinerator in the study area. We determined the mercury accumulation history in sediments of a lake centrally located in the study area. Recent maximum mercury accumulation rates in the sediment of the lake of ~ 88 μg/m 2 /year were highly elevated on a watershed area adjusted basis compared to other lakes in the Northeast and Minnesota. Fish from the study area lakes had significantly (p=0.05) greater total mercury concen- trations than fish from 24 more rural, non-source- impacted lakes in other regions of the state (LMB n=238, YP n=381) (LMB: 1.5-2.5 x; YP: 1.5 x). The integration of this extensive fish tissue data set, depositional modeling projections, historical record of mercury accumulation in sediments of a lake in the area, and knowledge of substantial mercury emissions to the atmosphere in the area support designation of this area as a mercury depositional and biological concentration hotspot in the late 1990s, and provides further evidence that major mercury point sources may be associated with significant local impacts on fisheries resources.

Mercury accumulation in sediments along an eutrophication gradient in Guanabara Bay, southeast Brazil

The accumulation of Hg was investigated in sediment cores from Guanabara Bay, Rio de Janeiro, Brazil, sampled along an eutrophication gradient, which was reflected in the sediment physical quality and total organic carbon (TOC) distribution. Sediments from the western bay area are strongly affected by inputs of urban and industrial effluents, showing Hg concentrations up to 7500 ng g-1 and Hg inventories up to 786 mg m-2, in contrast with near-background values found in the northwestern bay area (< 65 ng g-1 and 10.6 mg m-2). A shift from a negative to a positive relationship between Hg and TOC occurred in the most eutrophicated estuary, in which an upward increase in the recorded Hg levels was observed. This increase may be attributed to (i) an increasing riverine Hg input and (ii) an impact of eutrophication on the sediment quality, which may enhance the sediment capacity to accumulate organic matter-bound Hg.

Mercury Accumulation in Sediments of a Mangrove Ecosystem in SE Brazil

The Hg accumulation in sedimentary environments of a mangrove ecosystem in Sepetiba Bay, SE Brazil, was investigated. These environments include sediments of a mangrove forest, the main tidal creek that drains the forest, and the bare seaward-edge mud flat adjacent to forest and tidal creek. Maximum Hg concentration peaks in sediments from the mud flat (184 ng g-1), tidal creek (98 ng g-1), and mangrove forest (60 ng g-1) correspond to enrichment factors of 6.1, 3.3, and 2.0 above the estimated average background level, respectively. Average inventories of Hg excess (background-corrected) concentrations were substantiallydifferent between environments, decreasing from mud flat sediments (5.2 mg m-2) to creek sediments (3.3 mg m-2)to mangrove forest sediments (0.9 mg m-2). Mercury concentration profiles indicated a consistently higher accumulation of Hg in surface layers of mud flat and tidal creeksediments, whereas mangrove forest sediments showed a higher Hgaccumulation in root-rich subsurface layers, in agreement with an enrichment of Fe and organic matter contents. While Hg distribution in mud flat and tidal creek sediments appears to belargely affected by contamination, its distribution in mangrove forest substrate appears to be greatly affected by root-sedimentinteractions. Mercury levels in the study site were comparable tothose observed in coastal sediments under moderate Hg contamination at local and regional scales. Results indicate thatsedimentary environments surrounding the mangrove forest retain most of the anthropogenic Hg reaching the ecosystem. Since tidal waters have been previously demonstrated as the main source of metals to the site, it is suggested that the Hg retention in mudflat sediments precede and may avoid a higher Hg accumulation inlandward environments.

The use of a mathematical model to evaluate mercury accumulation in sediments and recovery time in a coastal lagoon (Ria de Aveiro, Portugal)

The urge of restoration and management of vital ecosystems (mainly those that affect directly human health) has become one of the most requested priorities. Ria de Aveiro (a lagoon on the north-western coast of Portugal) has an important economic role in local and surrounding areas due to its variety of resources. Studies have shown that there is an effective risk of hindering traditional activities due to high levels of mercury. Mercury concentrations in 1985 ranged from 0.7 μg g−1 to 850 μg g−1 in surface sediments and concentrations up to 25 μg g−1 fresh weight in fishes. A mathematical model (ECoS) was used to perform a simulation of mercury accumulation in surface sediments along the most contaminated channel from the beginning of the industrial discharges (in the 50's) until present days and recovery time for a zero mercury discharge from 1995 until 2045. The model shows that the amount of mercury in the surface sediments would decrease exponentially due to both deposition of mercury free particles and ressuspension of less and less contaminated particles. The model estimated levels actually measured along the channel and evaluated that, even after 40 years, mercury concentration would be approximately 50 μg g−1 in the most contaminated section of that channel if the discharges were discontinued now.

The use of a mathematical model to evaluate mercury accumulation in sediments and recovery time in a coastal lagoon (Ria de Aveiro, Portugal)

The urge of restoration and management of vital ecosystems (mainly those that affect directly human health) has become one of the most requested priorities. Ria de Aveiro (a lagoon on the north-western coast of Portugal) has an important economic role in local and surrounding areas due to its variety of resources. Studies have shown that there is an effective risk of hindering traditional activities due to high levels of mercury. Mercury concentrations in 1985 ranged from 0.7 μg g−1 to 850 μg g−1 in surface sediments and concentrations up to 25 μg g−1 fresh weight in fishes. A mathematical model (ECoS) was used to perform a simulation of mercury accumulation in surface sediments along the most contaminated channel from the beginning of the industrial discharges (in the 50's) until present days and recovery time for a zero mercury discharge from 1995 until 2045. The model shows that the amount of mercury in the surface sediments would decrease exponentially due to both deposition of mercury free particles and ressuspension of less and less contaminated particles. The model estimated levels actually measured along the channel and evaluated that, even after 40 years, mercury concentration would be approximately 50 μg g−1 in the most contaminated section of that channel if the discharges were discontinued now.