Showing papers in "Water Air and Soil Pollution in 1998"

The Relationship between Stream Chemistry and Watershed Land Cover Data in the Mid-Atlantic Region, U.S.

Abstract: In order to investigate the relationship between stream chemistry and watershed land cover at the regional scale, we analyzed data from 368 wadeable streams sampled in the mid-Atlantic region of the U.S. during spring 1993–1994. Study sites were selected using a probability sample and the digitized version of the 1:100,000 scale USGS map stream network as the sample population. Both classified Thematic Mapper (TM) and USGS Land Use/Land Cover (LULC) data were used to quantify land cover in the study watersheds. On average, the most common land cover was forest (77%) followed by agriculture (20%), and urban (1%). Multiple regression analysis showed that concentrations of Cl−, nutrients, acid neutralization capacity, and base cations were the analytes most strongly related to watershed land cover. Despite large differences in resolution and age of the TM and LULC data sources, similar results were obtained with the two sources. Using a greater number of land cover subclasses did not greatly improve the land cover-chemistry relationships. Ecoregions with predominantly forested land cover had weaker relationships than ecoregions with more agricultural and/or urban land cover. In studies or databases without land cover information, Cl− concentration is a good surrogate indicator for general human disturbance in the watershed.

Effect of Organic Materials on Partitioning, Extractability and Plant Uptake of Metals in an Alum Shale Soil

Abstract: Soils developed on sulphide-bearing shale (alum shale) in Norway contain naturally high amount of heavy metals. We conducted a greenhouse pot experiment to study the effect of four rates (0, 2, 4, and 8%) and three sources (cow manure, pig manure and peat soil) of organic matter in partitioning and distribution, extractability and plant uptake of Cd, Cu, Ni and Zn in an alum shale soil. Sequential extraction scheme was used to determine the distribution patterns of metals in the soil. DTPA was used for extracting the metals from the soil. Wheat (Triticum aestivum) was used as a test crop to study the plant uptake of metals. The highest amount of Cd was present in the exchangeable fraction, irrespective of the rate and source of organic matter applied. Copper, Ni, and Zn, on the other hand, were present only in small quantities in this fraction. The largest fraction of Cu was associated with organic matter and the amounts present in the oxide, carbonate and exchangeable fractions were very small. Nickel and Zn were found mainly in the residual fraction. Increasing rates of cow and pig manure decreased the amounts of Cd and Ni associated with the exchangeable fraction whereas, the addition of peat soil at the same rate increased the amounts of these metals associated with this fraction. This effect of organic matter was primarily associated with the change in soil pH caused by different organic matter sources. The DTPA-extractable metals were decreased with increasing rates of organic matter application, irrespective of its source. Grain and straw yields of wheat were decreased with increasing rates of organic matter. The application of organic matter increased the Cu and Zn concentrations in both grain and straw. The concentration of all metals was lower in plants grown in the cow manure amended soil as compared to those grown in the soil amended with either pig manure or peat soil. These results sugggest that the source of organic matter was a determining factor for metal distribution in the soil and for metal uptake by plants. In this study cow manure slightly increased the soil pH and thus was more effective than either pig manure or peat soil in reducing the plant uptake of metals but in general the efficiency of the organic material in reducing heavy metal uptake was small.

Mercuty in Precipitation and Its Relation to Bioaccumulation in Fish: A Literature Review

Abstract: Increases in industrial mercury (Hg) emissions in recent years have led many researchers to believe that Hg from the atmosphere constitutes a main source of Hg to aquatic biota in the absence of point source discharges. Established background levels for fish (0.2–1.0 mg kg-1) now exceed the pre industrial level of 0.15 mg kg-1, suggesting an anthropogenic origin. This review of recent literature illustrates how levels of mercury (Hg) species in the atmosphere are effectively transported into the aquatic arena, where chemical parameters combine to determine bioaccumulation rates in fish. Limited studies on methyl mercury (MeHg) in precipitation shown that concentrations average from 5% of total-Hg (T-Hg), to 1% in industrial regions. Observations of increased Hg is snow and precipitation from the Arctic Circle, related to poleward atmospheric circulation patterns, also demonstrate a spring maximum accompanying ozone depletion. Increases in oxidants and soil derived Hg in the atmosphere during the summer best explain summer Hg maximums observed in precipitation, while increased temperatures raise fish metabolism increasing Hg uptake through respiration and ingestion rate. The major route of entry for MeHg to fish appears to be biomagnification, after input from precipitation, runoff and inlake methylation. Regions buffered against acid precipitation maintain low fish-Hg levels by reduced MeHg production and maintaining gill function. When considering the bioaccumulation of Hg in fish this study shows that there are many variables to consider, not all of which originate from inside the aquatic arena. Both catchment and atmospheric processes combine with aquatic variables to dictate the overall levels of MeHg observed in fish tissue. There now appears to be sufficient knowledge to develop an axiom for the identification of aquatic systems likely to be susceptible to bioaccumulation from atmospheric derived Hg.

Synthesis of Nitrogen Pools and Fluxes from European Forest Ecosystems

Abstract: To investigate which ecosystem parameters determine the risk and magnitude of nitrate leaching we compiled data from published and unpublished sources on dissolved inorganic nitrogen (DIN: NO3 − + NH4 +) in throughfall, DIN leaching loss in runoff or seepage water, and other ecosystem characteristics from 139 European forests. Not all data were available for all sites: 126 sites had at least one year’s data on DIN inputs and DIN leaching loss; 40–50 sites had some data on soil chemistry and/or vegetation pools of N. DIN inputs in throughfall range between < 1 and about 70 kg N ha−1 yr−1 and the losses with seepage or runoff range between < 1 and 50 kg N ha−1 yr−1. Retention of N within the ecosystem increases with increasing DIN deposition and increasing proportion of NH 4 + in deposition. The amount of N in needles and litterfall shows a significant linear relationship with throughfall deposition of DIN, whereas the C:N ratio of the organic (OH) horizon is uncorrelated to the level of throughfall-DIN flux. About 50% of the variability in DIN leaching loss can be explained by the flux of DIN in throughfall. Alternatively, about 60% ofthe variability in DIN leaching loss can be explained in a two-variable multiple regression combining the C:N ratio of the organic soil and the pH of the mineral soil. The survey data suggest that leaching of DIN from forest ecosystems in Europe is related in part to current DIN deposition and in part to the longer-term internal ecosystem N status as reflected in the chemistry of the humus and acidification status of the soil.

Heavy metal fractionation and extractability in dredged sediment derived surface soils

Abstract: The objective of this study was to characterise pollution with heavy metals in surface soils sampled at various dredged sediment disposal sites in the Flemish region (Belgium). The sites selected varied in the period since sediment disposal ceased and in current vegetation and land use.

Effects of exotic plant species on soil properties in hardwood forests of New Jersey.

Abstract: Two exotic plant species, Berberis thunbergii and Microstegium vimineum, recently have invaded deciduous hardwood forests in the Northeast. We examined changes in soil properties that maybe associated with this invasion in three parks in northern New Jersey. In each park, we collected soil and vegetation data along transects that were established across heavily infested areas and extended into uninvaded forest. The data were analyzed statistically by ANOVA and Canonical Correspondence Analysis (CCA). Significant differences were found between invaded and uninvadcd plots in both soil and vegetation characteristics. Invaded areas have fewer oaks (Quercus spp.) in the canopy, and lack the native understory shrubs (Vaccinium spp.). The pH of soils in the invaded areas is significantly higher than in the uninvaded areas, and the litter and organic horizons are thinner. The data cannot show that the exotic species have caused these changes. However, the occurrence of contrasting soils in adjacent areas of native vegetation, with no evidence of differences in land-use history between areas, suggests that such a cause-and-effect relationship exists. We propose a feedback loop involving the exotic plants, and the presence of earthworms to explain these dramatic soil differences.

Effects of chronic nitrogen amendments on production of dissolved organic carbon and nitrogen in forest soils

Abstract: Chronic N deposition has been hypothesized to affect DOC production in forest soils due to the carbon demand exerted by microbial immobilization of inorganic N. We tested this hypothesis in field experiments at the Harvard Forest, Petersham, Massachusetts, USA. During four years of sampling soil solution collected beneath the forest floor in zero-tension lysimeters, we observed little change in DOC concentrations (10-30% increase, not statistically significant) associated with elevated N inputs, but did observe significant increases in DON concentrations. Both DOC and DON varied seasonally with highest concentrations in summer and autumn. Mean DON concentrations increased 200-300 % with the highest rate of inorganic N fertilization, and concentrations of DON were highest in samples with high inorganic N concentrations. We conclude that the organic chemistry of soil solution undergoes qualitative changes as a result of long-term N amendment at this site, with small changes in DOC, large increases in DON, and a decline in the C:N ratio of dissolved organic matter.

Synthetic Fibers as Indicators of Municipal Sewage Sludge, Sludge Products, and Sewage Treatment Plant Effluents

Abstract: Because of concerns regarding health, safety, and aesthetics, a test that identifies the presence of sewage sludge or its products (biosolids) in commercial materials such as soil conditioners and composts would be useful. This test could also trace the effluent plume from a sewage treatment plant. We have discovered that synthetic fibers serve as such an indicator. Synthetic fibers are abundant in sludge, sludge products, and sewage treatment plant effluents. The fibers evidently are introduced from clothes-washing machines and survive the sewage treatment process. Synthetic fibers were identified using polarized light microscopy, which provided a simple, rapid method for determining the presence or absence of municipal sewage sludge or its products. False positives or false negatives have not occurred with any of the materials examined so far. We also monitored synthetic fibers in surface sediments of Huntington Harbor, Long Island, NY, a harbor receiving the effluent from a trickling filter sewage treatment plant. Fibers generally decrease in size and abundance with distance from the source. In Oyster Bay Harbor, Long Island, an advanced sewage treatment plant is operated with a final microfiltration step. Synthetic fibers are less abundant in the sediments of this harbor.

Climate change as the primary cause for pH shifts in a high alpine lake

Abstract: Chemical and biological sedimentary records of a high alpine lake were used to reconstruct palaeoecological conditions and compared with two centuries of instrumental temperature measurements. Air temperature determined the lake water pH throughout the past 200 yr almost regardless of the level of atmospheric deposition. Our data suggest a strong climate forcing of the acid-base balance in sensitive high-altitude lakes. Their physico-chemical conditions and biota strongly depend on the duration of ice and snow cover which is significantly different between warm and cold periods. Beside changes in weathering rates, in-lake alkalinity generation and water-retention time, delayed freezing in autumn and earlier ice-out dates with a shorter duration of CO2 over-saturation could be crucial for the tight temperature-pH coupling.

Factors Controlling Mercury Transport in an Upland Forested Catchment

Abstract: Total mercury (Hg) deposition and input/output relationships were investigated in an 11-ha deciduous forested catchment in northern Vermont as part of ongoing evaluations of Hg cycling and transport in the Lake Champlain basin. Atmospheric Hg deposition (precipitation + modeled vapor phase downward flux) was 425 mg ha−1 during the one-year period March 1994 through February 1995 and 463 mg ha−1 from March 1995 through February 1996. In the same periods, stream export of total Hg was 32 mg ha−1 and 22 mg ha−1, respectively. Thus, there was a net retention of Hg by the catchment of 92% the first year and 95% the second year. In the first year, 16.9 mg ha−1 or about half of the annual stream export, occurred on the single day of peak spring snowmelt in April. In contrast, the maximum daily export in the second year, when peak stream flow was somewhat lower, was 3.5 mg ha−1 during a January thaw. The fate of the Hg retained by this forested catchment is not known. Dissolved (< 0.22 pm) Hg concentrations in stream water ranged from 0.5–2.6 ng −1, even when total (unfiltered) concentrations were greater than 10 ng L−1 during high flow events. Total Hg concentrations in stream water were correlated with the total organic fraction of suspended sediment, suggesting the importance of organic material in Hg transport within the catchment. High flow events and transport with organic material may be especially important mechanisms for the movement of Hg through forested ecosystems.

Temporal Changes in Cadmium, Thallium, and Vanadium Mobility in Soil and Phytoavailability under Field Conditions

Abstract: A field study was conducted over a 30 mo period to examine movement of Cd, Tl, and V through the profile of a Coastal Plain soil (Typic Kandiudult) and the availability of these trace metals to bush bean (Phaseolus vulgaris L) plants The metals were applied to field plots as dissolved salts and mixed into the surface 75 cm The greatest concentration of all three metals was observed in the surface soils, with a steep decrease occurring down to the 75 to 15 cm depth Thallium was the most mobile of the three metals; approximately 15% of the applied Tl and <3% of the applied Cd and V moved below the surface 75-cm region during the 30-mo experiment Extractable concentrations of all three metals in the surface soils decreased significantly (P ≤005) during the initial 18 mo after treatment No further decrease occurred between 18 and 30 mo The presence of Al- and Fe-oxides and small amounts of clay minerals and organic matter in this highly-weathered, low cation-exchange soil were likely responsible for the retention of the trace metals Bioavailability, as measured by concentrations and total amounts of metals in root and aboveground tissues of plants, did not change significantly between 18 and 30 mo These data suggest that bioavailability of Cd, Tl, and V decreased over time as a result of transformation of these elements into unavailable forms and not to leaching These changes in bioavailability occurred soon after application, becoming negligible after 18 mo

Recovery of Surface Waters in the Northeastern U.S. from Decreases in Atmospheric Deposition of Sulfur

Abstract: A simple mass flux model was developed to simulate the response of SO 4 2− concentrations in surface waters to past and anticipated future changes in atmospheric deposition of SO 4 2− Values of bulk (or wet) SO 4 2− deposition and dry deposition of S determined from measured air concentrations and a deposition velocity were insufficient to balance watershed SO 4 2− export at the Hubbard Brook Experimental Forest, NH and for a regional survey of watersheds in the northeastern US We propose two explanations for the unmeasured S source: 1) a significant underestimation of dry S deposition, and/or 2) internal watershed S sources, such as weathering and/or mineralization of soil organic S Model simulations based on these two mechanisms agreed closely with measured stream SO 4 2− concentrations at Hubbard Brook Close agreement between measured and model predicted results precluded identification of which of the two mechanisms controlled long-term trends in stream SO 4 2− Model simulations indicated that soil adsorption reactions significantly delayed the response of stream water to declines in SO 4 2− inputs since 1970, but could not explain the discrepancy in watershed S budgets Extrapolation of model predictions into the future demonstrates that uncertainty in the source of the S imbalance in watersheds has important implications for assessments of the recovery of surface water acid neutralizing capacity in response to anticipated future reductions in SO2 emissions

Atmospheric deposition of trace metals at three sites near the great lakes

Abstract: The concentrations of vanadium (V), chromium (Cr), manganese (Mn), nickel (Ni), copper (Cu), zinc (Zn), arsenic (As), selenium (Se), cadmium (Cd), and lead (Pb) in precipitation and on airborne particles were measured at three Integrated Atmospheric Deposition Network (IADN) monitoring stations on Lakes Superior, Michigan and Erie during 1993 and 1994. These data were used to estimate annual wet and dry deposition fluxes at these sites. In most cases, both wet and dry deposition make an important contribution to the total atmospheric flux of trace metals. Total (wet + dry) annual loadings of Zn and Cr are higher at the Lake Erie site than at the Lake Michigan and Lake Superior sites. Atmospheric loadings of the other metals are similar at all three sites. Wet deposition of metals is more closely related to precipitation amount than to the concentration of metals in the precipitation. Dry deposition fluxes are controlled by the concentration of trace metals on large particles. Total particle mass concentrations are higher during the summer and fall at the Lake Erie site, however no seasonal trends in total particle mass at the other sites or trace metals at any of the sites were detected. The total atmospheric loadings calculated in this work are in agreement with other estimates of metals deposition to the Great Lakes.

A Critical Evaluation of Sample Pretreatment for Storage of Contaminated Sediments to be Investigated for the Potential Mobility of their Heavy Metal Load

Abstract: The identification of the geochemical forms of heavy metals in contaminated sediments gives information on their availability. This requires the use of a geochemical speciation procedure such as the one developed by Tessier et al. (1979). In addition to the imperfections of these protocols, their results can vary depending on the technique used for the preservation of sediments which must be suited to the materials studied and to particularities of the investigation. This study was carried out on superficial river sediments, seriously polluted by Cu, Cd and Pb. Compared to fresh sediment, none of the drying methods studied (freeze-drying, air-drying and oven-drying at 105 °C) completely preserve the distribution of Cu, Pb, Zn and Cd in the various geochemical fractions of the sediment. The modifications depend directly on the quantities of metals present in the various fractions of the sediment, the effects being more marked when the quantity is smallest. This results in a decrease in metals in the exchangeable fraction and in those bound to carbonates under the action of atmospheric oxygen and a corresponding increase in the other fractions. To minimize this, freeze-drying and air-drying are satisfactory techniques which enable preservation of sediments representative of the environment.

Fenton Reagent Advanced Oxidation of Polynuclear Aromatic Hydrocarbons in Water

Abstract: Aqueous oxidation of three polynuclear aromatic hydrocarbons, fluorene, phenanthrene and acenaphthene with the combination of hydrogen peroxide and ferrous ion, Fenton reagent, has been studied The effect of variables such as concentration of both reactants, pH and presence of bicarbonate ion and humic substances has been investigated Products resulting from oxidation have also been identified From experimental results and kinetic data determined the process is confirmed as an advanced oxidation involving the generation of hydroxyl radicals Oxidation rates are even higher than those from other advanced oxidation systems involving ozone, UV radiation and hydrogen peroxide Reactivity is in the following decreasing order: Phenanthrene > Fluorene > Acenaphthene

Absorption of heavy metals in wild berries and edible mushrooms in an area affected by smelter emissions

Abstract: The total concentrations of nickel, copper, chromium, strontium, arsenic, lead, cadmium and cobalt were measured in berries and mushrooms, as well as manganese and iron in mushrooms. The study area (about 3500 km2) is situated on the border of the northern taiga and tundra forests (68–69°N) and is affected by emissions from the extensive Ni-Cu smelter complex at Monchegorsk, Kola Peninsula, NW Russia. Part of the study area, extending along the railway line used for transporting apatite concentrate, contains elevated quantity of strontium. Berries of Vaccinium vitis-idaea (82 samples), Vaccinium myrtillus (28), Rubus chamaemorus (42) and Empetrum hermaphroditum (40) and mushrooms of Leccinum auantiacum (47 samples), Leccinum scabrum (32), Russula vesca (25), Lactarius torminosus (8), Lactarius trivialis (9), Suillus luteus (10) and Xerocomus subtomentosus (20 specimens) were collected from 98 locations during 1987–1992. The nickel and copper concentrations in the berries, and nickel in mushrooms, correlated satisfactorily with the corresponding metal concentrations in the soil. The berries and mushroons growing over an area of at least 3000 km2 around the smelter complex are unsuitable for human consumption due to the elevated nickel concentrations caused by the smelter dust emissions. The berries and mushrooms gathered in the studied polluted forests were found to be contaminated by nickel by a factor of 15–30 times (berries) and 15–40 times (mushrooms) more than the background level. Increased levels of strontium were found close to the railway line. The concentrations of all the other metals in the studied area did not exceed sanitary standards.

Leaching of Nutrients, Organic Carbon and Iron from Finnish Forestry Land

Abstract: This study provides an assessment of the spatial variability of the long-term leaching of nutrients, total organic carbon (TOC) and iron (Fetot,) from 22 forested catchments (0.69–56 km2), distributed across all but the northenmost areas of Finland. The natural, unmanaged Kruunuoja catchment is located in a national park, while the other catchments represent Finnish forestry land. The average leaching of Ptot (4.2 kg km−2 yr−1) from the Kruunuoja catchment was small compared to the catchments representing forestry land (on average 10 kg km−2 yr−1). Moreover, P fertilization was the most important predictor for the spatial variation in Ptot leaching (r2 = 0.45). Leaching of TOC, Fetot and N compounds was not closely related to forestry practices. Median C/N ratio in the study streams was high (range 34–66). The average inorganic N proportion and leaching of NO 3 − -N were lowest in the Kruunuoja catchment (7.3 % and 2.8 kg km−2 yr−1, respectively) and highest in the southernmost Teeressuonoja catchment (54 % and 100 kg km−2 yr −1, respectively) located in the highest N deposition area. The most important forestry practices since the 1960’s have affected about 2.4 % of the area of study sites per year (cf. 2 % in the entire country in 1991). Moreover, the mean annual runoff from the catchments (230–430 mm yr−1) agrees with the mean annual runoff from Finland (301 mm yr−1). Consequently, the results of the study catchments can be used to estimate average total annual leaching from Finnish forestry land: 2,700 t of Ptot, 48,000 t of Ntot, 110,000 t of Fetot and 1.5 million t of TOC.

Bacterial Biodiversity in Soil with an Emphasis on Chemically-Contaminated Soils

Abstract: Microorganisms isolated from soil are sources of known and new microorganisms and genetic material. This review examines general principles of soil bacterial biodiversity, limitations in sampling soils, and examples of bacterial diversity in chemically-contaminated soils. Both conventional and molecular methods used to assess microbial biodiversity in soils will be addressed as well as selected examples of the effects of organic and inorganic pollutants on soil microbial diversity.

Tracing Hydrologic Pathways Using Chloride at the Panola Mountain Research Watershed, Georgia, USA

Abstract: An analysis of chloride (Cl−) concentrations and fluxes at the 41 ha Panola Mountain Research Watershed indicates that Cl− may be used effectively to differentiate “new” and “old” water flow through the hillslope and their respective contributions to streamwater. Rainfall and throughfall, the “new” water inputs, are marked by low Cl− concentrations ( 30 µeg L−1). Timing of soil water transport is not sufficiently rapid to suggest that soil water from this hillslope site (20 m from the stream) contributes to streamwater during individual rainstorms. The source of streamflow, therefore, must be a combination of channel interception, overland flow and soil water from near-channel areas, and runoff from a 3 ha bedrock outcrop in the headwaters. Groundwater contribution to streamflow was estimated using CF concentrations of throughfall and groundwater as the two end members for a two-component hydrograph separation. For the study period, groundwater contributed 79% of the streamflow and from 1985 to 1995, contributed 75% of the streamflow. Rainfall was the source of 45% of the Ct flux from the watershed in the long term; the remaining Cl− is hypothesized to be derived from dry deposition, consistent with the enrichment noted for throughfall. At peak flow during individual rainstorms, “new” water can contribute 95% of the runoff.

Uranium Solubility of Carbonate-Rich Uranium-Contaminated Soils

Abstract: A 300 d solubility study involving two carbonate-rich, uranium-contaminated soils from the Department of Energy's Fernald Environmental Management Project site was conducted to predict the behavior of uranium during on-site remediation of these soils. Geochemical modeling was performed on the aqueous species dissolved from these soils following the solubility measurements to predict the on-site uranium leaching and transport potential. Results showed that the soluble levels of the major components (total uranium, calcium, magnesium, and carbonate) increased continually for the first 4 weeks. After the first 4 weeks, these components either reached a steady-state or continued to increase linearly throughout the study. Soluble uranium levels of both soils and their correlation with alkalinity was strongly mediated by the source term of the contamination. Geochemical modeling predicted and anion exchange experiments confirmed that uranyl-carbonate complexes were the most stable and abundant complexes. Further modeling showed that uranium solubility in these soils and in onsite groundwater wells is controlled by UO2(H2PO4)2, but is also mediated by complexation with carbonate and the oxidation state of the uranium. For assessing the risk related to off-site transport of uranium, it should be recognized that the solubility of uranium-bearing minerals is the critical factor in controlling uranium solubility of these soils rather than sorption/desorption processes as measured by the uranium distribution coefficient (Kd) in these soils.

Speciation and Concentrations of Mercury in Certain Coastal Marine Sediments

Abstract: Concentrations of total mercury (Hg), methyl Hg and Hg(II) were determined in coastal marine sediments collected from the Baltic, South China and the Bering Seas. Methyl Hg concentrations in sediments were between 0.01 and 2 ng g-1 on a dry weight basis, accounting for only <1% of the total Hg concentrations. The percentage of Hg(II) (i.e. available Hg) in total Hg was between 5 and 13 suggesting that most of the Hg in sediments was bound as HgS and/or Hg-humic complexes. Relatively larger proportion of methyl Hg was found in less polluted freshwater sediments than in marine sediments. Methyl Hg concentrations in marine sediments were not found to be correlated with total Hg and/or Hg (II) concentrations.

Chemical partitioning of heavy metals in soils, clays and rocks at historical lead smelting sites

Abstract: The chemical partitioning of lead and zinc is described in contaminated soils and underlying strata at historical lead smelting sites. Sections of soil-rock cores from eight sites of age 200 to c.1900 yr were analysed using a sequential extraction procedure. Of the total amount of lead and zinc present in soils, only a small proportion is in a readily mobile form. However, this proportion increases significantly as the pH falls below 5 and for lead reaches 37% in soils at Bole A. A high proportion of lead in soils appears to be associated with the carbonate and specifically adsorbed phase. It is suggested that this is partly due to the formation of cerussite (PbCO3) in soils contaminated with calcareous slag wastes. Lead present in the residual phase in contaminated soils may be related to the presence of the element in silicate slag particles. Rapid migration of lead to a depth of 5.6 m in sandstone at Bole A was related to its high solubility in the acidic soils and rock at this site. Comparable migration at Bole C proceeds by a different mechanism, possibly with lead in association with Fe-Mn oxides and slag particles. In clay infill in fractured sandstone at Bole A, anthropogenic lead present at a depth of 4.4 m was extracted predominantly in the fraction representing Fe-Mn oxides.

Variations of soil nutrient and organic matter content in a subtropical mangrove ecosystem

Abstract: Variations of soil nutrient and organic matter content along tidal gradients of a small mangrove forest in Hong Kong were investigated. Effects of sampling months on nutrient status were also analysed. Two transects, A and B, were established perpendicular to the shoreline. Transect A transverse a wider band of vegetation and was less disturbed by human activities; while Transect B was close to human settlement and all mangrove plants were more frequently flooded by incoming and outgoing tides. Surface soils at 5 and 10 m intervals along Transects A and B, respectively, were collected in December 1989, March 1990, July 1990 and September 1990. Concentrations of soil organic matter, total and extractable nitrogen, phosphorus and potassium were high in landward sites and decreased gradually along tidal gradients; while pH and salinity increased with distance from landward to seaward sites. These trends along tidal gradients indicate the importance of tidal frequency and amplitude on soil properties. Significant differences in soil properties were also found between two transects. Transect A had significantly higher organic matter and nutrient content than Transect B. In both transects, there were sites with extraordinarily high levels of nutrients and organic matter (5–10 times higher than the average values) suggesting local contamination. Most of these contaminated sites were located at the landward edges. Positive correlations between organic matter, N, P and K content were found suggesting that these nutrients were from similar input sources. Variations along tidal gradients and local contaminated sites at the landward edges suggest that human discharges, litter deposition and surface runoff were major nutrient inputs. In both transects, no definite seasonal periodicity was found and temporal variations existed in a more random manner than variations along tidal gradients.

Wastewater irrigation effect on soil, crop and environment : A pilot scale study at Irbid, Jordan

Abstract: An investigation was carried out at pilot scale to test the feasibility of using the effluent of a rotating biological contactors (RBC) unit treating wastewater generated from a university campus. The objective of the study was to cerefully monitor the impact of wastewater irrigation on the soil, percolating water, crop growth and the pathogenic condition within the immediate vicinity of wastewater application.

Canopy and Soil Retention of Nitrogen Deposition in a Mixed Boreal Forest in Eastern Finland

Abstract: Nitrogen deposition, leaching, and retention were monitored in a mature spruce (Picea abies Karsten) dominated mixed boreal forest in eastern Finland Bulk precipitation, throughfall, stemflow, and percolation through the podzolic soil profile were monitored from 1993 to 1996 Mean annual bulk deposition of total N was 383 kg ha−1, of which 33 % was NH 4 + -N, 26 % was NO 3 − -N, and 41 % was organic N Throughfall+stemflow flux of total N was 293 kg ha−1 yr−1 Sixty-four % of NH 4 + -N and 38 % of NO 3 − -N in bulk precipitation was retained by the tree canopy Organic N was released (027 kg ha−1 yr−1) from the tree canopy Nitrate-N was retained and organic N was leached as the water passed through the ground vegetation and soil O-horizon Ammonium-N and organic N were retained mainly in the E-horizon The output of total N from the E-horizon was only 5 % of the total N deposition in the forest stand during the study period and it was mainly as organic N The output of inorganic N forms from under B-horizon was seasonal and occurred mainly at spring snowmelt

Soil Surface Geochemical Anomaly Around the Copper-Nickel Metallurgical Smelter

Abstract: The soils were sampled from the center of airborne contamination caused by long time activity of a copper/nickel smelter complex in the Kola Peninsula, Russia. The soil specimens were taken from an area about 250 km2, which included the town of Monchegorsk, with frequency of 1 sample (plot) per 3 km2 and heavy metals nickel, copper, cobalt, chromium, lead, cadmium, strontium, iron, manganese and arsenic were measured. The soil surrounding the Smelter, including the inhabited territory of the town, was found to be contaminated by nickel and copper to levels 450- and 250 times higher in comparison to the background, respectively. These soils were found to be extremely toxic and represented a severe threat to human health. Elevated concentrations of iron and arsenic caused by smelter emissions were found too.

Effect of Fluctuating Hydrological Conditions on the Mobility of Heavy Metals in Soils of a Freshwater Estuary in the Netherlands

Abstract: The objective of this study was to measure the mobility of heavy metals in freshwater estuary soils that are seasonally inundated and to characterize the distribution of sulfide precipitates in these soils. Precipitation and dissolution of labile sulfides may account for changing pore water concentrations of heavy metals in freshwater wetland soils that are subject to temporary flooding or fluctuating groundwater levels. The presence of authigenic zinc- and iron-(mono)sulfide in this type of soils during periods with a high groundwater level was demonstrated by electron microprobe analyses. Because sulfide precipitates are strongly associated with root remnants, fresh soil organic material may be an important intermediary in the sulfur cycling and, consequently, in the behavior of heavy metals in these freshwater soils. Oxidation of labile sulfides may be partly responsible for the increased zinc and sulfate concentrations in the pore water during periods with low groundwater levels. Heavy metals may also be mobilized by degradation of their host phase organic matter during periods with high biodegradation.

Biogeochemistry of Iron and Sulfur in Sediments of an Acidic Mining Lake in Lusatia, Germany

Abstract: Chemical, microbiological and stable isotope analyses of sediments from an acidic mining lake were used to evaluate whether biogeochemical processes, such as iron and sulfate reduction, are extant, because such processes can potentially generate alkalinity. Sediment cores were sliced in cm intervals to achieve a high resolution for spatial distribution of organic and inorganic components. Iron, sulfur, carbon, nitrogen and phosphorus as well as the most probable number (MPN) of iron reducing bacteria, the amount of lipid phosphate and the stable isotope compositions of various sedimentary sulfur compounds were measured. Accumulation of degradable organic material, reduced mass fractions of iron, enhanced concentrations of lipid phosphate, high concentrations of DOC and ferrous iron in the pore water and a drastic change of sulfur isotope ratios in the upper 3 cm of the sediment all indicated a highly reactive zone of biogeochemical transformations. The data provide clear evidence for iron and sulfate reducing processes in the sediments that result in an increase of pH with depth.

Historical Variations in Lead Fluxes in the Pyrenees (Northeast Spain) from a Dated Lake Sediment Core

Abstract: Variations in Pb concentration in lake sediments reflect changes in the fluxes of this element in the past. A sediment core from a lake in the Pyrenees (Lake Redo at 2,240 m a.s.l., NE Spain) was studied, with the aim of reconstructing past environmental and climatic conditions in the lake and its catchment area. The core was dated using both 210Pb and 14C. A surface peak of Pb concentration, which was about 10 times higher than the background level, was found. This peak is attributed to mining activities since the beginning of this century. Although Pb pollution due to the combustion of gasoline is expected to be present, no evidence can be deduced from Pb isotope ratios of sediment due to the masking effect of Pb from mines. A second peak appeared in a deeper layer, with a maximum Pb concentration of about 17 times higher than the background level. The origin of this peak is unclear. All evidence suggests that the ancient peak is due to mining operations in the central Pyrenees area, which were not documented historically.

Acidification of Freshwater Wetlands: Combined Effects of Non-Airborne Sulfur Pollution and Desiccation

Abstract: In recent decades, SO 4 2− concentrations have increased in groundwater and surface water of freshwater wetlands. For many minerotrophic peatlands, S originating from SO 4 2− -polluted groundwater and surface water is a more significant source of SO 4 2− than the actual atmospheric deposition of S compounds. Lowered groundwater tables in wetlands, as a result of either natural or anthropogenic desiccation, may cause acidification because of concomitant geochemical oxidation processes. The impact of the enhanced availability of reduced S compounds, due to preceding SO 4 2− pollution, on these processes was tested in a mesocosm experiment, using soil cores including vegetation from a mesotrophic wet meadow. The soils had been maintained in waterlogged condition for seven months, using two environmentally relevant SO 4 2− concentrations (2 and 4 mmol L−1). The groundwater table was reduced in two successive steps: 10 cm below soil surface, and complete desiccation. Control pretreated soils did not show a decrease in soil pH during desiccation, due to adequate buffering by bicarbonate. However, both SO 4 2− -pretreated groups showed a significant drop in pH (from 6.5 to 4.5) caused by additional sulfide oxidation, leading to high SO 4 2− concentrations (10 and 16 mmol L−1, respectively). Cation exchange and acidification-related solubilization processes induced the mobiliztation of base cations and potentially phytotoxic metals like Al. Nutrient concentrations in soil moisture were influenced strongly by SO 4 2− pretreatment, showing distinct patterns for P, N and K. Therefore, S polluted groundwater and surface water may severely increase the sensitivity of wetlands to desiccation. The results are discussed in relation to wetland management.