Distribution Of Mercury In Sediments Research Articles

Mercury monitoring in the coastal areas of the Republic of Korea using the black-tailed gull egg as an indicator

In the southeast and east coasts of the Republic of Korea, it is essential to monitor mercury accumulation in coastal organisms in view of the higher mercury distribution in sediments and human samples. However, mercury pollution monitoring in organisms, especially higher trophic-level organisms that can exhibit high mercury accumulation, is limited. Here, we examined the applicability of the eggs of the black-tailed gull (Larus crassirostris), which belongs to a high trophic level, for mercury monitoring in coastal areas. Breeding sites were selected in West, Southeast, and East Seas with different mercury concentrations in other matrices (sediment and biological samples of residents). The 5-year mean total mercury concentration in eggs collected during the breeding seasons from 2016 to 2020 was lower in Baengnyeongdo (705 ± 81 ng/g dry weight (dry), West Sea) than in Hongdo (1,207 ± 214 ng/g dry, Southeast Sea) and Ulleungdo (1,095 ± 95 ng/g dry, East Sea). The different patterns of mercury concentration in gull eggs among the breeding sites was consistent with those in the other matrices among the coastal areas. These results support the applicability of the black-tailed gull egg as an indicator for establishing a monitoring framework in the coastal areas of the Republic of Korea.

Pattern of mercury distribution in sediments from an irregular hydrological regime estuary

The Patos Estuary, in southern Brazil, is subject to an irregular hydrological regime and receives mercury (Hg)-contaminated effluents from the city of Rio Grande since the colonial period of southern Brazil. Aiming to investigate sulfate reduction effects over Hg geochemistry in a shallow area (SA) and a salt marsh (SM) from the Patos Estuary, four sediment cores were collected during two distinct hydrological regimes (i.e., freshwater dominated and brackish water dominated). An assessment of free dissolved sulfide (ΣS−II) concentration and pH in pore water and metals (Fe and Hg), fine grained (<63μm) and organic carbon (OC) contents in sediment allowed us to conclude that mercury distribution in SA is chiefly controlled by <63μm sediments and metal sulfide formation. Furthermore, redox conditions were relatively stable during both sampling periods. Nevertheless, bioturbation promotes oxygen penetration and subsequent acidification of pore water associated with upper sediment layers in SM, especially during the brackish water period. Most likely, such oxidizing conditions hamper sulfate reduction and, thereafter, Hg immobilization via the formation of metal sulfides. No evidence of anthropogenic contamination was found in the studied sediments.

Distribution of mercury in sediments, plant and animal tissues in Matang Mangrove Forest Reserve, Malaysia

Charcoal production activities at the Matang Mangrove Forest Reserve (MMFR) in Peninsular Malaysia have a potential to emit volatile compounds such as Hg back into the ambient environment, raising concerns on the public health and safety. The present study was aimed at analyzing Hg concentration from different plant/animal tissues and sediment samples (in total 786 samples) to understand clearly the Hg distribution at the MMFR. Leaves of Rhizophora spp. showed higher Hg concentration with an increasing trend from young, to mature, to senescent and decomposing stages, which was possibly due to accumulation of Hg over time. The low Hg concentration in Rhizophora roots and bark suggests a limited absorption from the sediments and a meagre accumulation/partitioning by the plant tissue, respectively. In the case of mangrove cockles the concentration of Hg was lower than the permissible limits for seafood consumption. Although the mangrove gastropod - Cassidula aurisfelis Bruguière had rather elevated Hg in the muscle tissue, it is still less than the environmental safely limit. Beside the chances of atmospheric deposition for Hg, the sediment samples were found to be unpolluted in nature, indicating that in general the MMFR is still safe in terms of Hg pollution.

Mercury Distribution of Benthonic Animals and Response to Mercury in Sediments in Caohai Wetland, Guizhou Province

Caohai wetland is a National Nature Reserve. Benthic animals were collected from the deep-water area in the middle of Caohai Lake and the shallow-water area in the surrounding marshes, and mercury and methyl mercury distributions in the benthic animals were analyzed and discussed. The risk of mercury pollution was evaluated. The concentrations of total mercury and methyl mercury in the benthonic animals were in the range of 0.51-46.55 ng·g-1 with an average of 7.82 ng·g-1 and 0.04-27.71 ng·g-1 with an average of 4.31 ng·g-1, respectively. This was lower than reports from other natural reserves. By contrast, the total mercury and methyl mercury in the benthic animals in summer were higher than in other seasons, which was consistent with the characteristics of methyl mercury distribution in sediments but opposite to the spatial distribution characteristics of total mercury in sediments. The methyl mercury contents in Cipangopaludina cathayensis were positively correlated with the content of methyl mercury in the sediments (r=0.52, P<0.05). The results showed methylation and the bioavailability of mercury in sediments from the shallow-water area were obviously higher than those from the deep-water area in the middle of Caohai Lake. The difference in organic matter content of the sediment or the wet-dry alternation (flooding-receding-flooding) in the surrounding shallow marshes was suspected to be associated with the obvious difference. The high enrichment coefficient of total mercury and methyl mercury in benthic animals were sufficient to raise the risk of mercury contamination in the aquatic food chain in the wetland.

Assessment of mercury contamination based on mercury distribution in sediment, macroalgae, and seagrass in the Todos os Santos bay, Bahia, Brazil.

The Todos os Santos bay (TSB) is the second largest Brazilian bay. Despite the large number of potential anthropogenic sources of mercury (Hg) in the bay, data on this element in this marine environment are very scarce. Total Hg concentrations were therefore determined in sediment, macroalgae, and seagrass species collected during dry and rainy seasons, from eight locations. In ~45% of the sediment samples, Hg concentration was two to four times higher than the upper value considered the regional Hg background (15μgkg(-1)). Geoaccumulation index indicated that Hg contamination was at none to heavily contaminated. In Padina sp., Caulerpa sp., Hypnea sp., and Halodule wrigthii, Hg concentrations ranged from 10.61-297.61, 15.59-74.50, 12.84-158.03, and 4.02-67.25μgkg(-1), respectively.

Distribution of mercury in sediments from Kagoshima Bay, Japan, and its relationship with physical and chemical factors

Kagoshima Bay is located on the south coast of Kyushu Island, Japan. Submarine fumaroles present in the northern area have been identified as a natural source of mercury in the bay. The aim of the present work is to study the spatial distribution of mercury in the bottom sediments of the bay and its relationship with major physicochemical properties that might affect the transport of mercury in the ecosystem surrounding this area. Sediment core samples were collected in the north and central areas in surveys performed during 2011 and 2013. The individual core samples were sliced and processed for the analysis of total mercury (T-Hg), chemical composition, total organic carbon (TOC), particle size and magnetic susceptibility. The horizontal distribution of T-Hg indicates that fumaroles are the primary source of Hg in the area; the results indicate a key role of organic matter binding to Hg. In the area to the west of the fumaroles, the relationship between Hg and TOC is characterized by two linear trends that correspond to the upper and lower sections of the cores. From the physicochemical properties, it was suggested that the two distinct linear relations might be caused by a change of the volcanic activity at the Aira Caldera, which is located at the northern part of the bay. The extent of the bay impacted by the Hg generated from the hydrothermal vents has decreased in recent years and is limited to the vicinity of the emission point.

Mercury distribution in sediments of a shallow tropical reservoir in Brazil

Mercury distribution in sediments of a shallow tropical reservoir in Brazil

Mercury distribution in sediment along urban–rural gradient around Shanghai (China): implication for pollution history

The increasing levels of heavy metals in the environment generally related with the rapid industrialization and urbanization. Mercury (Hg) is a global toxin with wide concerns, and China gradually becomes the main producer, consumer, and emitter of Hg in the world. However, few historical data are available on the occurrence of Hg in Chinese urban areas. Here, we collected 35 lake surface sediment samples from 35 public parks and 1 sediment core in the Luxun Park in Shanghai, a hyper-urbanization city in China, to determine the spatial and vertical distributions of total mercury (THg) and methylmercury (MeHg) and to explore the Hg pollution history with the industrial development. Higher concentrations of Hg and MeHg and greater Hg enrichment were found in urban areas compared with suburban area with the following order: central urban core area > developed urban area > developing urban area > suburban area. The THg concentration in the sediment core showed an increasing trend from 1876 to 2000 and a decreasing trend from 2000 to 2012, coinciding with the process of industrialization and urbanization in Shanghai. However, THg fluxes unceasingly increased from 1876 to present probably attributed to coal consumption in the suburban area and transportation agglomeration in the central urban core area. Unlike THg, no significant variations for MeHg with time and the maximum value (0.17 μg/kg) appeared in 1947. The methylation ratio of MeHg to THg in the sediment is pretty low, and more studies are needed to further understand the fate of Hg in the environment.

Regional distribution of mercury in sediments of the main rivers of French Guiana (Amazonian basin).

Use of mercury (Hg) for gold-mining in French Guiana (up until 2006) as well as the presence of naturally high background levels in soils, has led to locally high concentrations in soils and sediments. The present study maps the levels of Hg concentrations in river sediments from five main rivers of French Guiana (Approuague River, Comté River, Mana River, Maroni River and Oyapock River) and their tributaries, covering more than 5 450 km of river with 1 211 sampling points. The maximum geological background Hg concentration, estimated from 241 non-gold-mined streams across French Guiana was 150 ng g-1. Significant differences were measured between the five main rivers as well as between all gold-mining and pristine areas, giving representative data of the Hg increase due to past gold-mining activities.These results give a unique large scale vision of Hg contamination in river sediments of French Guiana and provide fundamental data on Hg distribution in pristine and gold-mined areas.

Effect of penguin and seal excrement on mercury distribution in sediments from the Ross Sea region, East Antarctica

Total mercury (Hg) concentration and several other geochemical parameters were determined for five sediment profiles from the Antarctic Ross Sea region. Our data exhibit significant positive correlations between Hg concentration and total organic carbon (TOC) content in all profiles, suggesting the predominant role of organic matter (OM) as a Hg carrier. The OM in the sediments originates primarily from penguin guano and algae. High Hg content in guano and a positive correlation between Hg and a guano bio-element (phosphorus, P) in the ornithogenic sediment profiles (MB6, BI and CC) indicate that Hg was strongly influenced by guano input. The bottom sediments of MB6 with seal hairs contain relatively high Hg. This increase is attributed to the input of seal excrement, suggesting that sedimentary Hg may be an effective trophic-level indicator from seals to penguins. The enrichment factor (EF) for Hg was calculated and the results indicated apparent Hg enrichment in the sediment profiles from the Ross Sea region caused by bio-vectors such as penguins and seals. Compared with typical sediments from other sites in Antarctica and the SQGs (sediment quality guidelines), the total amount of Hg in our study area is still not considered to be adversely high.

The influence of mariculture on mercury distribution in sediments and fish around Hong Kong and adjacent mainland China waters

To study the influence of mariculture on mercury (Hg) speciation and distribution in sediments and cultured fish around Hong Kong and adjacent mainland China waters, sediment samples were collected from six mariculture sites and the corresponding reference sites, 200–300 m away from the mariculture sites. Mariculture activities increased total mercury, organic matter, carbon, nitrogen and sulfur concentrations in the surface sediments underneath mariculture sites, possibly due to the accumulation of unconsumed fish feed and fish excretion. However, methylmercury (MeHg) concentrations and the ratio of MeHg to THg (% MeHg) in sediments underneath mariculture sites were lower than the corresponding reference sites. The % MeHg in sediments was negatively correlated ( r = −0.579, p < 0.05) with organic matter (OM) content among all sites, indicating that OM may have inhibited Hg methylation in surface sediments. Three mariculture fish species were collected from each mariculture site, including red snapper ( Lutjanus campechanus), orange-spotted grouper ( Epinephelus coioides) and snubnose pompano ( Trachinotus blochii). The average MeHg concentration in fish muscle was 75 μg kg −1 (wet weight), and the dietary intake of MeHg through fish consumption for Hong Kong residents was 0.37 μg kg −1 week −1, which was lower than the corresponding WHO limits (500 μg kg −1 and 1.6 μg kg −1 week −1).

Urban activity and mercury contamination in estuarine and marine sediments (Southern Brazil)

The distribution of mercury in sediments of the Patos Lagoon estuary and nearby coastal marine deposits has been investigated for the period 1998-2008. Polluted urban soils and coastal reclamation fills are the principal sources of high mercury concentrations for shallow estuarine sediments. The shallow sediments that form near the urban area enter the navigation canal and are transported into the ocean. The mercury concentration in sediments of the navigation canal has considerably increased since 2004, due to intense reconstruction activity in the urban area. Periodic dredging of the canal strengthens the preconditions for coastal marine sediment contamination by mercury. However, this does not occur because the resuspended dredged sediments are significantly diluted by natural suspended particulate matter.

Influence of submarine fumaroles on the distribution of mercury in the sediment of Kagoshima Bay, Japan

To estimate the influence of mercury emitted from submarine fumaroles, the horizontal and vertical distribution of mercury in sediment of Kagoshima Bay was studied. The fumaroles are located in the northern bay head area, and the sediment samples had been taken from 52 points throughout the bay with a gravity core sampler. The core samples obtained were cut at a thickness of 1–2 cm and used for measurements. The total concentration of mercury in surface sediment in the northern and central areas of the bay was 51–679 μg kg − 1 (average 199 μg kg − 1 , n = 22) and 23–100 μg kg − 1 (average 55 μg kg − 1 , n = 30), respectively. The highest value was obtained in the vicinity of the fumaroles. The mercury concentration in sediment near the fumaroles varied with depth, which may reflect the variation in fumarolic activity. A successive extraction method was applied to the speciation of mercury in the sediment. The results showed that sediment taken in the vicinity of submarine fumaroles contained a higher percentage of mercury bound with organic matter.

Spatial and temporal patterns in mercury contamination in sediments of the Laurentian Great Lakes

Data from recent sediment surveys have been collated and mapped in order to determine the spatial distribution of mercury in sediments across the entire Great Lakes basin. Information from historical surveys has also been collated in order to evaluate temporal trends. Lake Huron (2002) exhibited the lowest mercury concentrations (lakewide average concentration, 0.043 μg/g); Lakes Michigan (1994–1996) and Superior (2000) also exhibited relatively low levels (lakewide averages of 0.088 and 0.078 μg/g, respectively). The western basin of Lake Erie (1997–1998, 0.402 μg/g) and Lake Ontario (0.586 μg/g) exhibited the highest levels. Sources of mercury contamination in Lakes Erie and Ontario are primarily attributed to loadings from historical sources, including chlor-alkali production in the Detroit, St. Clair, and Niagara Rivers. The spatial distributions of mercury in sediments of Lakes Huron and Superior suggest that natural geochemical factors are an influence. Surficial sediment mercury contamination was found to have decreased markedly since the late 1960s and 1970s. Decreases in lakewide average sediment concentrations of mercury over this time period ranged from approximately 25% for Lake Ontario to 80% for Lake Huron.

Distribution of mercury in sediments from La Paz lagoon, Peninsula of Baja California, Mexico.

La Paz lagoon is located in the southeastern portion of the Peninsula of Baja California (Fig. 1). The drainage area of the lagoon has an unique geological setting, a zone of tectonic crustal deformation and is cut by active faults (Angelier et al. 1981, Hausback 1984, Henry 1989). The lagoon is a semi-enclosed shallow marine system, separated from the main part of the La Paz Bay by a sandy barrier named El Mogote. It is connected to the main body of water by means of a tidal channel 300-800 m wide with a maximum depth of 10 m.

Mercury distribution in sediments and bioaccumulation by fish in two oregon reservoirs: point-source and nonpoint-source impacted systems.

Mercury pollution was compared in two Oregon reservoirs of similar size and age, located within the same ecoregion. Cottage Grove Reservoir was distinguished by a history of mercury mining and processing within its watershed, while Dorena Reservoir was not. Mercury concentrations in sediments of the reservoirs, tributary streams, and three species of fish were measured. Sediment mercury concentrations in the main tributary of Cottage Grove Reservoir, which drains the subbasin where past mercury mining occurred, was tenfold higher than mercury in sediments from other reservoir tributaries. There were no significant differences between sediment mercury concentrations in the tributaries of Dorena Reservoir. The average mercury concentration in the basin sediment of Cottage Grove Reservoir (0.67 +/- 0.05 microg/g dry wt) was higher than for Dorena Reservoir (0.12 +/- 0.01 microg/g dry wt). At Cottage Grove Reservoir, maximum mercury concentrations were near or exceeded 1 microg/g wet wt for largemouth bass (Micropterus salmonides) and bluegill (Lepomis macrochirus) epaxial muscle. Muscle mercury concentrations in largemouth bass and crappie (Pomoxis nigromaculatus) from Cottage Grove Reservoir were significantly higher than from the same species from Dorena Reservoir. Numbers of bluegill of the same age available from both reservoirs were too small for statistical comparisons. Mercury concentrations in largemouth bass muscle fluctuated annually in both reservoirs. Fish ages were consistently positively correlated with muscle mercury concentrations in only the point-source-impacted reservoir. These results indicated that a point source, Black Butte Mine, contributed amounts of mercury greatly in excess of mobilization from natural deposits, atmospheric deposition, and small-scale uses of the metal as an amalgamating agent in gold mining.

Vertical distribution of mercury in sediments from the East Pacific Rise

Concentrations of mercury are often high in waters and sediments associated with volcanic hydrothermal systems, in both marine and terrestrial environments. Whereas the concentration of mercury in open ocean waters is reported to be in the range 0.002–0.05 µg 1−1 (refs 1–4), significantly higher values of up to 1.4 µg l−1 are reported in waters near, or having circulated through, areas of submarine hydrothermal activity2,5. Mercury concentrations of up to 400 p.p.b. (parts per 109) on a carbonate-free basis (CFB) have been measured in surface sediments on the East Pacific Rise crest, but concentrations decrease to <20 p.p.b. (CFB) on the peripheral seafloor6. Similar high concentrations from 160 to 890 p.p.b. (CFB) have been recorded in near-surface sediments from the median valley of the Mid-Atlantic Ridge7. We report here on the vertical variations of mercury in sediments from the East Pacific Rise, and suggest that increased concentrations are correlated with periods of increased submarine volcanic activity.