Soil Hg Concentrations Research Articles

Foliar exchange of mercury as a function of soil and air mercury concentrations

Previous research has indicated that foliar mercury (Hg) flux is bi-directional, with influence from both atmospheric and soil Hg. This work investigated the role of soil and air Hg concentrations on foliar Hg exchange using a single-plant gas-exchange system. The exchange of Hg vapor with aspen seedlings grown in soil Hg concentrations of 0.03±0.01, 5.8±0.5, and 12.3±1.3 μg g −1 and exposed to atmospheric Hg concentrations of 2.4±0.5, 11.0±0.9, and 30.4±2.2 ng m −3 was measured. At background atmospheric Hg concentrations of 2.4 ng m −3, foliage released Hg at all three soil Hg concentrations and fluxes ranged from 1.6 to 5.5 ng/m 2/h. At higher atmospheric Hg concentrations (>11 ng m −3), net deposition to foliage ranged from −9 to −47 ng/m 2/h, exhibiting increase uptake with higher air Hg concentrations. Fluxes associated with aspen showed an immediate response to changes in atmospheric Hg concentrations. Compensation points, the air concentration where no net flux of Hg vapor occurred, were 3–4 ng m −3 in the light and 2–3 ng m −3 in the dark for trees grown in soils of 0.03 and 6 μg g −1 Hg content, and 5–6 ng m −3 in the light and 2.5–3.5 ng m −3 in the dark for trees grown in 12 μg g −1 Hg soils.

A Review Of Mercury in Lake Victoria, East Africa: Implications for Human and Ecosystem Health

Lake Victoria, East Africa, has been the site of many recent studies measuring mercury (Hg) concentrations in water, fish, sediment, soil, and humans. Most of these studies were motivated by concerns about Hg contamination from processing of gold ore on the southern shores. Total Hg (THg) concentrations in fish were usually below permissible World Health Organization (WHO) concentrations and international marketing limits and do not threaten the lucrative export industry. Nile perch 3-10 kg and most >10 kg had THg concentrations above the WHO threshold concentrations for at-risk groups (200 ng/g). Elevated THg concentrations in large Nile perch are not of major concern because Nile perch are rarely consumed by the people living on Lake Victoria and very large Nile perch are becoming increasingly rare in catches. Water THg concentrations were below Canadian drinking water guidelines but were elevated relative to those in the northern Great Lakes. Sediment and soil THg concentrations were within inter-national guidelines and are comparable to those in northern latitudes but are lower than those in the Amazon basin. Biomass burnings and soil erosion are estimated to be the major sources of THg for the lake and probably constitute a larger source of THg than gold mining in Tanzania.THg concentrations in urine and hair from human volunteers indicate that while gold miners and frequent skin-bleaching cream users are at risk of inorganic mercury poisoning, the rest of the population, including fishermen, is not. Human exposure assessments demonstrated that fish consumption and soil geophagy constitute major sources of THg for humans, but the total estimated daily intake of THg was below the Health Canada tolerable daily intake (TDI) limits. The use of beauty creams containing high inorganic Hg concentrations, however, caused the estimated THg exposure to exceed the TDI. The high THg content in the hair of regular cream users supports this assessment. The nutritional benefits of fish and soil geophagy outweigh the risk of THg poisoning. Still, due to the importance of those natural items as a THg source to humans, as well as the changing nature of Lake Victoria, regular monitoring and risk assessments need to be carried out in the Lake Victoria catchment.

Estimating distribution and retention of mercury in three different soils contaminated by emissions from chlor-alkali plants: part I.

Mercury emissions from chlor-alkali plants have been past and present sources of soil contamination with Hg. Here we calculate net mercury (Hg) deposition to soils in the vicinity (100-1000-m downwind) of three-chlor alkali plants. Calculations were based on spatial distribution patterns of Hg concentrations in soils, which were extrapolated by kriging. Moreover, we investigated to what extent Hg deposition depends on the elevation of receptors and canopy throughfall. Mercury concentrations in soil exceed background values up to a factor of 56 and show enrichment factors between 2 and 5.8 calculated from the median Hg concentration. Net deposition rates range between 2356 and 8952 microg m(-2) year(-1), which is up to 224-fold the background values. Net deposition of Hg to soils at the three sites varies between 1.2 and 2.4% of total emitted Hg. Highest deposition rates were found at sites with extended elevated or forested areas. Here, Hg concentrations in soils increased by a factor of up to 7.3 in elevated (+180 m) forest areas compared to non-elevated grassland soils.

Distribution of mercury in soil and its concentration in runoff from a biosolids-amended agricultural watershed.

Biosolids applications can significantly increase Hg concentrations in cultivated soils. The objective of this study was to quantify levels of mercury in soils and runoff from a biosolids-amended watershed. The study site was a terraced, cultivated watershed that received cumulative biosolids loadings of 0, 87, or 224 Mg ha(-1) between 1974 and 1993. Snowmelt runoff samples were collected from the three treatment areas in the spring of 1995. Soils were collected along transects from the 0 and 224 Mg ha(-1) biosolids treatment areas at depths of 0 to 15 and 15 to 30 cm. Mercury analysis of stored, freeze-dried biosolids samples showed that Hg concentrations during the 20-year study ranged from 12.4 mg kg(-1) initially to 2.4 mg kg(-1) near the end. Soil Hg concentrations were elevated in the surface (0-15 cm) and subsurface (15-30 cm) of the 224 Mg ha(-1) biosolids-treated terrace relative to the control. Mercury concentrations in the 0- to 15-cm soil depth ranged from 30 to 50 microg kg(-1) for the control terrace and 180 to 390 microg kg(-1) for the 224 Mg ha(-1) biosolids-treated terrace. Concentrations were lower in the 15- to 30-cm depth. Total Hg concentrations in snowmelt from the control terrace ranged from 9.2 to 27.9 ng L(-1) and 19.8 to 44.8 ng L(-1) for the biosolids-treated terraces. Most Hg was associated with particulates > 0.45 microm. Mercury concentrations were elevated in grass tissue growing near the watershed's runoff lagoon.

Impact of Atmospheric Long Range Transport of Lead, Mercury and Cadmium on the Swedish Forest Environment

Emissions of Hg, Pb, and Cd to air aretransported over wide areas in Europe and deposited far awayfrom their sources. About 80% of the atmospheric depositionof these metals in south Sweden originate from emissions inother countries. As a result of the increased anthropogenicdeposition the concentrations of Hg, Pb, and Cd in the morlayer of forest soils have increased considerably, mainlyduring the 20th century. Although the atmosphericdeposition of these elements has declined during the mostrecent decades, the reduction of the input of Hg and Pb isnot sufficient to prevent a further accumulation. Theconcentrations of Hg and Pb are still increasing by ca. 0.5and ca. 0.2% annually in the surface layer of forest soils.In contrast, the Cd concentration is currentlydecreasing in a large part of Sweden as a result of bothdeposition decreases and enhanced leaching induced by soilacidification. The accumulation factors of Hg and Pb,especially in the forest topsoils of south Sweden, arealready above those at which adverse effects on soilbiological processes and organisms have been demonstrated instudies of gradients from local emission sources andlaboratory assessment. There are also indications of sucheffects at the current regional concentrations of Hg and Pbin mor layers from south Sweden, judging from observationsin field and laboratory studies. There is an apparent riskof Pb induced reduction in microbial activity over parts ofsouth Sweden. This might cause increased accumulation oforganic matter and a reduced availability of soil nutrients.At current concentrations of Hg in Swedish forest soils,effects similar to those of Pb are likely. Increasedconcentrations of these elements in organs of mammals andbirds have also been measured, though decreases have beendemonstrated in recent years, related to changes inatmospheric deposition rates. As a result of current andpast deposition in south Sweden, concentrations of Hg infish have increased about fivefold during the 20thcentury. This implies risks for human health, when fish frominland waters are used for food. Although the concentrationof Hg in fish has decreased ca. 20% during the last decade,probably as a result of the reduced deposition, the levelstill exceeds the general limit (0.5 mg kg-1) in about half(ca. 40 000) of the Swedish lakes. In order to reduceconcentrations in fish to the level recommended, and avoidfurther accumulation of Hg in soils, the atmosphericdeposition has to be reduced to ca. 20% of the current deposition rate. This can only be achieved by international co-operation.

Characterization of Compost Produced at a Golf Course: Impact of Historic Mercury Accumulations In Putting Green Soil

This paper reports on the physical and chemical properties of feedstock and compost materials used at the Clear Lake Golf Course located in southwestern Manitoba. The compost was found to have a very low organic matter content (range = 9.1 to 13.2%) and a low moisture content (27.8 to 32.8%). To improve the compost quality, two recommendations were made: (1) a composting pad should be installed to prevent soil contamination and (2) the moisture content should be monitored, particularly during the curing stage. The compost contained Hg concentrations ranging from 3.16 to 6.1 mg kg−1. The grass clippings, the primary feedstock material, had Hg concentrations ranging from 8.53 to 20.2 mg kg−1. The putting green soil Hg concentration ranged from 60.7 to 90.8 mg kg−1. Elevated Hg levels may have been due to previous mercurial fungicide use and all the values were well above the Canadian compost and soil guideline values of 0.8 and 6.6 mg kg−1, respectively. It was estimated that 104.4 kg of Hg has accumulated in the top 8 cm of the putting green soil, which cover an area of 9,290 m2. Based on a Hg flow analysis conducted on the solid materials entering and leaving the putting green soil, a passive remediation approach was recommended that involved: (1) removal of the aeration cores, (2) restrictions on the compost use, (3) construction of a composting pad, and (4) the periodic monitoring of the soil and compost Hg concentrations. Calculations suggested the soil would reach the soil quality guideline value in approximately one hundred years. This is a long period of time, and, as the data suggests a degree of bioavailability, the impact of the long-term exposure to golf course staff must be determined. As there are thousands of golf courses in North America that may have been treated with mercurial fungicide, a health risk assessment should be done on the Hg exposure levels during the handling and processing of the aeration cores and grass clippings.

Arsenic and mercury concentrations in major landscape components of an intensively cultivated watershed

To provide an understanding of arsenic (As) and mercury (Hg) concentrations in soil, sediment, water, and fish tissues, samples were collected from a Mississippi River alluvial floodplain located in northwest Mississippi. As concentrations increased approximately an order of magnitude from water (5.12 μg/l) to fish tissues (36.99 μg/kg) and an additional two orders of magnitude in soils, lake sediments, and wetland sediments (5728, 5614, and 6746 μg/kg), respectively. Average Hg concentrations in water, soils, lake sediments, and fish were 2.16 μg/l, 55.1, 14.5 and 125 μg/kg, respectively. As and Hg concentrations were within published ranges for uncontaminated soil, water, and sediments. As concentrations represented a low risk. Hg concentrations were also low but showed a greater tendency to concentrate in fish tissue. The dominant mode of entry of these materials into aquatic systems is through storm-generated runoff. Since both metals accompany sediments, agricultural conservation practices such as reduced tillage, buffer riparian strips, and bordering sediment ponds or drainage wetlands will minimize watershed input to aquatic systems.

Distribution of mercury in soils at a decommissioned gas plant

The range and distribution of mercury in soils at a decommissioned gas plant near Turner Valley, Alberta were investigated in order to facilitate risk assessment and the remediation and development of the site into a tourism area. Although high levels of Hg were thought to be present in some areas on the site, it was unclear whether the source of the Hg was industrial processes or from river deposition of HgS impurities after erosion of upstream sulfide deposits. Background Hg concentrations in undisturbed soils and surficial bedrock near the gas plant were also unknown. Mercury concentrations in surface soil material on the gas plant site were found to range up to 230 mg Hg kg−1 soil, with the highest concentrations found next to process building doorways. Investigation of Hg distribution with soil depth showed that levels were generally highest at the surface, dropping rapidly with depth to near background levels of 0.07 mg Hg kg−1 soil or lower. The highest Hg concentrations were associated with the clay fraction, which contained up to 2300 mg Hg kg−1 soil. The results are consistent with an anthropogenic source from spillage of elemental Hg contained in manometers and pressure monitoring devices used in plant buildings. Mercury concentrations at depth and in uncontaminated surface soils were similar to those reported by Dudas and Pawluk (1976) for surface soils formed in glacial and fluvial deposits elsewhere in Alberta. Key words: Mercury, contamination, soils, Turner Valley

Mercury flux measurements in a naturally enriched area: Correlation with environmental conditions during the Nevada Study and Tests of the Release of Mercury From Soils (STORMS)

An international intercomparison of micrometerological techniques and dynamic flux chamber methods applied to measure mercury fluxes was conducted from September 1 to 4, 1997, during the Nevada Study and Tests of the Release of Mercury From Soils (STORMS) in Reno, Nevada. Nine research groups from four countries met in the Steamboat Springs, Nevada Geothermal Area, to participate in the first international flux intercomparison ever attempted for mercury. The highly heterogeneous soil Hg concentrations and complex landscape within the study area (4 ha) were unfavorable for spatial intercomparison of Hg fluxes between the research groups. However, reliable and correlated Hg fluxes were measured between our micrometerological technique and a dynamic flux chamber method (r2 = 0.29), run side by side (5 m). Hg fluxes and their relationships with environmental factors were complex. After ∼90 days of dry condition, a series of storm events impacted the site and increased the soil moisture from <0.5 to 6.6%. This appeared to promote strong Hg evasion during the transition period from dry to wet soil conditions. However, the subsequent relationship between soil moisture and Hg flux was significantly negatively correlated. Multivariate analysis was applied to extract the principal components (principal component analysis). Three principal components were extracted (explained up to 79% of the total variance) and discussed with respect to their environmental signification. Environmental conditions under southern wind sectors were optimal to promote Hg fluxes. Turbulence rather than Hg air concentrations seemed to be the main factor promoting the determined Hg fluxes during this study.

Bioindication of heavy metals in the town Wrocław (Poland) with evergreen plants

In this paper the results are reported of a study on the concentration of macroelements (N, P, K, Ca, Mg, S and Fe) and heavy metals (Ni, Cr, Co, V, Zn, Mn, Pb, Cd, Cu, Hg, Ba and Sr) in soil and in three species of the evergreen plants Ilex aquifolium, Mahonia aquifolium and Rhododendron catawbiense. These plants are collected in the Botanical Garden of the Polish town Wrocław (which is exposed to atmospheric exhausts of heavy traffic, chemical factories, metal smelters and a heat and power plant partly alimented with lignite and coals) and in two presumed unpolluted reference (background) sites, one in Poland (the Dendrological Garden in Wojslawice near Niemcza, south from Wrocław) and the other in The Netherlands (the Botanical Garden of the University of Nijmegen). Analyses of both soil and plant samples point to the pollution of the Wrocław Botanical Garden by Ni, Cr, Co, Cd via the atmosphere and pollution by Zn, Pb and Hg probably via atmosphere and soil. Especially pollution with Hg via soil is supported by a significant positive correlation between Hg content in soil and in all the examined species of which Ilex aquifolium seemed to be the best monitor of soil pollution with this element.

Methyl Mercury Contamination and Emission to the Atmosphere from Soil Amended with Municipal Sewage Sludge

AbstractIn an effort to identify the effect of municipal sewage sludge application on mercury (Hg) concentrations in soil, we studied the contamination of sludge‐amended soil with inorganic and methyl Hg and the emission of these contaminants to the atmosphere using a Teflon dynamic flux chamber. The routine application of municipal sewage sludge to cropland significantly increased both total and methyl Hg in surface soil from 80 to 6100 µg kg−1 and 0.3 to 8.3 µg kg−1, respectively. Both inorganic and methyl Hg were transported from the sludge/soil matrix to the environment by emission to the atmosphere, however, there was no indication of Hg transport in limited soil water lysimeter experiments. Our data from soil amended with municipal sewage sludge represent the first quantitatively measured terrestrial source of methyl mercury (MeHg) to the atmosphere. Sludge‐amended soil emitted an average of 12 to 24 pg m−2 h−1 of monomethyl Hg and ∼100 ng m−2 h−1 of inorganic Hg to the atmosphere. A simple dispersion model suggests that sludge‐amended soil may increase regional atmospheric MeHg concentrations by ∼5%. These data highlight the need for further research to quantify the transport of Hg from sludge‐amended soil and identify the sources of MeHg in the atmosphere.

Concentrations and Distributions of Eleven Metals in Florida Soils

Concentrations and distributions of 11 elements—Hg, Cd, As, Cu, Cr, Pb, Ni, Zn, Mn, Al, and Fe—in 40 Florida soil profiles (94 soil samples) were investigated. The soils were classified as Spodosols, Entisols, and Ultisols, representing major mineral soils in Florida. The geometric mean concentrations of Hg, Cd, As, Cu, Cr, Pb, Ni, Zn, Mn, Al, and Fe in surface soils (A horizons) were 0.0042, 0.21, 1.1, 3.7, 3.9, 4.1, 6.5, 12, 25, 730, and 820 mg kg−1, respectively. Metal concentrations in these soils were lower than those of published values of Florida agricultural soils and U.S. soils. Metal contents, excluding Cd and Mn, were strongly correlated with clay content (r = 0.35–0.77), and some metals (Cr, Ni, Pb, and Al) were correlated with cation exchange capacity (r = 0.23–0.35). Metal distributions in soils, therefore, reflected parent-material and pedogenic factors determining clay content variations between and within soil profiles. Generally, metal contents in soils decreased in the order of Ultisols > Entisols ≥ Spodosols and Bt > Bh > A ≥ E horizons. All metals except Cd, Hg, and Mn were concentrated in Bt horizons; As, Cu, Cr, Fe, and Al were enriched in Bh horizons, where clay and organic matter had accumulated.

Multi-element contamination of soils and plants in old mining areas, U.K.

Soils and plants were sampled from some old Pb-Zn mining and smelting areas in England. The results show that Pb, Zn, Cd, Ag, As, Sb and Hg concentrations in soils and plants from these areas are highly elevated compared with “normal background” levels and the control sites in this study. The enrichment and associations of metals are affected by three factors. (1) The nature of the underlying mineralised rock. (2) The mining activities which have produced widespread contamination. (3) The smelter pollution resulting in very high concentrations of metals in the immediate vicinity and downwind of smelters. The natural multi-element associations and multi-element contamination in these historical Pb-Zn mining and smelting areas are dominated by the presence of sulphide minerals. The typical trace element associations found are: in mining areas Pb-Zn-Cd-Ag-As-Sb-Hg; and in smelter sites Pb-Zn-Cd-Sb-As. These soil and plant results indicate that, in addition to Pb, Zn and Cd, the other toxic elements As, Sb, Ag and Hg are present as significant contaminants.

Effects of emissions from a coal-fired power plant on surface soil trace element concentrations

Increase in trace element (As, Cd, Cr, Cu and Hg) concentrations in surface soils caused by deposition of emissions from a power plant was evaluated through field studies and model calculations. The enrichment discrimination factor (EDF) was used as an indication of the effects. Model calculations estimated that the maximum deposition of the elements would be located at a site 3 km north of the plant. The increase in EDF, ΔE, at the ssite due to cumulative depositions over 25 years was evaluated to be As:0.06, Cd:0.20, Cr:0.02, Cu:0.13 and Hg:0.08, respectively. In contrast, observed EDFs of each element at 30 sites within a 10 km radius from the plant fluctuated within the range far beyond the ΔE, and there was no statistically significant correlation among the EDFs as a function of distance or direction from the plant, suggesting that the effects of emissions lie concealed in normal ambient fluctuation of the element concentrations.

Mercury in swedish forest soils and waters — Assessment of critical load

As a result of air pollution, the content of Hg in fish has significantly increased in a large part of Scandinavia and North America. In this paper, the occurence and fluxes of Hg in Swedish forest soils and waters are reviewed and synthesized. The main objective is to describe and evaluate the present transport of anthropogenic Hg from atmospheric deposition, through the terrestrial compartment and running waters to lake basins and also to comprehend the main factors influencing these fluxes. The transportation and distribution. of Hg in forest soils and waters is closely related to the flow of organic matter. The content of Hg in humic matter is higher in southern and central areas compared to the north of the country. Compared to background concentrations, the Hg content has increased in the southern and central part by about a factor of 4–7, while the overall increase in the north is by about a factor of 2 to 3. The increased content of Hg in forest soils may have an effect on organisms and biological processes in the soil. Regarding budget calculations for whole catchment areas and for the mor layer of the soil, a reduction of about 80% from present atmospheric wet deposition must be obtained to reach “critical load” with respect to conditions in Scandinavia.

Anomalous Hg contents in soils of Niue Island, South Pacific.

Niue Island, a raised coralline atoll in the South Pacific, has soils that have long been known to have strongly anomalous radioactivity. We now show that there is also a highly anomalous Hg content in the soils. It is associated with the radioactivity and the goethite/gibbsite content and the values are as high as those in soils over known Hg-mineralisation in volcanic settings, though no mineralisation is known on Niue and such an occurrence on this coral island would be geochemically unusual.

Assessment of mercury dispersal in an abandoned mining area by soil and lichen analysis

The total Hg content in soil and in the epiphytic lichen Parmelia sulcata was determined in a former cinnabar mining area on Mt. Amiata. Metal concentrations in soil and in lichen are significantly related and decrease at increasing distances from the zone most affected by minespoil and by air which is still vented from mine shafts. On the basis of these results and of Al analysis, it seems likely that anomalous Hg content in Mt. Amiata lichens is mainly due to the out-gassing of volatile Hg from soil, from vegetation and, in the most heavily polluted zone, to the air from mine shafts.

A contribution to the environmental biology of mercury accumulation in plants

Samples of six common plant species collected in the old mining areas near Prince George, British Columbia (Canada) and Mount Amiata, Tuscany (Italy) show remarkable similarities in the variation of plant/soil Hg concentration ratio with soil Hg content irrespective of species or other biological differences. In contrast, plants sampled in the geothermally active areas of New Zealand, Hawaii and around Mount St. Helens exhibit more individuality in the concentration ratio to soil Hg relationship, but the relationships are distinctly different from the mine site specimens. This distinction is particularly evident when the same species of Equisetum and Plantago taken from these two different areas are compared. These and other data support the hypothesis that specific local environmental factors strongly influence the accumulation of Hg in plants even when the immediate soil concentrations are the same. Our findings show that some plants contain concentrations of total Hg as high as 5500 to 14000 μg kg−1 (dw).

Soil mercury study of thermal areas, Rincón de la Vieja Volcano, Costa Rica

Numerous thermal areas are found on the southwest flank of the active volcano Rincón de la Vieja, Costa Rica. These are part of a larger band of thermal areas that parallels the volcanic front for about 25 km. A total of 318 soil Hg samples were collected on the southwest flank of the volcano, predominantly at the Las Pailas hot springs. Soil Hg concentrations range from 6 to 180,000 ppb and can be divided into three populations with threshold values of 47 and 190 ppb. Aureole Hg values are widely distributed; anomalous soil Hg concentrations were found at four locations. Two-dimensional Fourier analysis of smoothed Hg values from the Las Pailas thermal area reveals a N70W trending lineament of high Hg concentration. This lineament is thought to indicate the presence of a fault along which upwelling of geothermal fluids is enhanced. The orientationof this fault coincides with the orientation of volcano alignments and structural features identified elsewhere in the region.

Heavy Metals and Persistent Organics at a Sewage Sludge Disposal Site

AbstractThere are problems associated with the utilization of sewage sludge as an agricultural fertilizer. One of the more pressing problems is the question of heavy metals and persistent organics. There is concern that indiscriminate disposal of sewage sludges on agricultural lands may lead to decreased crop yields, and/or may endanger the human food chain through excessive accumulation of some of these metals in edible portions of crops.The effects of sewage sludge disposal on agricultural land, and possible transmission of sludge contaminants into the food chain is a possible environmental problem. Soils, plants, and sewage sludge from the Metro Denver sewage sludge disposal site were examined for trace elements and persistent organics content. Concentrations of Zn, Cu, Ni, Cd, Pb, and Hg in soils increased when sludge was applied, whereas concentrations of As, Se, Mo, and 22 refractory organics were unaffected. Forage crops grown on these soils showed increased concentrations of Zn, Cu, Cd, and Ni; however, these metals were not elevated to a phytotoxic level or above ranges that would be considered normal for forage tissues. Concentrations of As, Se, and Hg in forage tissues were unchanged, while Pb concentrations decreased as a result of sludge applications. None of the forage tissues examined contained detectable levels of any of the 22 organics that they were analyzed for.Soil metals (Zn, Cu, Ni, Cd, and Pb) extracted with DTPA (diethylenetriaminepentaacetic acid) did not correlate with plant concentrations of these metals. Results indicated that the DTPA soil test could be used as a reliable index as to the total metal concentration of a soil, but not as an indication of heavy metal availability for crop uptake.Heavy metals and P remained within the depth of sludge incorporation. Nitrate concentrations, while decreasing with soil depth, showed that substantial amounts had leached to a 91‐cm depth.