Short-term effects of biosolid and municipal solid waste applications on heavy metals distribution in a degraded soil under a semi-arid environment

Digested biosolid (SS) and municipal solid waste (MSW) were surface-applied to a degraded carbonated soil, under semi-arid environment, at rates of 0 and 80 Mg/ha, to determine the changes in organic matter and in the distribution of heavy metals in the topsoil, 1 year after its application. Waste application slightly increased the organic matter content and improved the composition of humic fractions in the treated soils, mainly in the MSW amended plots. A sequential extraction method (Tessier et al., 1979) was used to determine the distribution of Cd, Cr, Cu, Ni, Pb and Zn in both the waste and the amended.soils. Waste application had little effect on the total concentration of Ni and Cr in the treated soils as a consequence of the low availability of these metals in the wastes. A considerable increase of Cd, Cu, Pb and Zn was observed as a consequence of the high content and/or high availability of these metals in the wastes. The more labile fraction (exchangeable fraction) of all metals studied increased slightly (< 1.5 mg/kg) when SS and MSW were added. However, a remarkable increase in the Fe/Mn oxide fraction of Cd, Cu and Pb and in the organic fraction of Zn were noted in treated plots, this increase being higher in the MSW treated soils.     

Evaluation of distribution, mobility and binding behaviour of heavy metals in surficial sediments of Louro River (Galicia, Spain) using chemometric analysis: a case study

Contents of total and extractable heavy metals, carbonates, MnO and Fe₂O₃, organic matter, and matrix components such as SiO₂, Al₂O₃, CaO, Na₂O, MgO, TiO₂, K₂O and P₂O₅ are used along with principal component analysis (PCA) for studying distribution, mobility and binding behaviour of Cd, Cr, Cu, Ni and Pb in the Louro River (Galicia, Spain). Eleven surficial sediment samples were taken along the beds of the river course. Total metal concentrations were obtained after microwave-assisted digestion whilst extractable metal contents were obtained following a three-stage sequential extraction scheme (i.e. soluble, reducible and oxidisable fractions). Loading plots of heavy metals bound to carbonates, Fe–Mn oxides, organic matter and aluminosilicates allowed determination of binding behaviour. Correlations found indicate that Pb and Cu are mainly discharged from urban wastes, whereas Cr and Ni are from electroplating and galvanizing industries. The occurrence of diffuse pollution sources along the river can account for the binding behaviour of Cd. Metal mobility decreased in the order: Cd>Pb>Cu>Ni>Cr. Despite total contents indicating moderate-to-high heavy metal pollution in this river, metals are mostly distributed in the residual fraction, hence showing a low risk of mobility.     

Partitioning of trace metals before and after biological removal of metals from sediments

Metal removal by biological solubilization in three strongly contaminated sediments was carried out in a two-liter stirred bioreactor. Biological treatment yielded metal removal efficiencies in the range of 11-30%, 43-57%, 60-79%, 61-90%, 18-21%, 0-10% for Pb, Cu, Zn, Cd, Ni and Cr, respectively. The treated sediments were then rinsed with a NaCl solution (0.5 M), resulting in an increase by nearly 47% in Pb removal for the three sediments, while for other metals (Cu, Zn, Cd, Ni, Cr), the NaCl rinse did not seem to allow any significant increase in metal solubilization. A standard procedure of sequential selective extraction (SSE) was applied to the sediments before and after each treatment. With regard to Pb, Zn and Cd, the carbonate bound fractions (2/3 sediments) represented 18-42% of metals prior to treatment, while the iron and manganese oxides bound fraction constituted 39-60% of metals for the three sediments. Between 90 and 100% of Pb, Zn and Cd removed by the process came from the fractions bound to carbonates and from those bound to Fe and Mn oxides. The organic matter and sulfide bound fractions contained 65-72% of total Cu present before treatment and the process removed, on average, 63% Cu present in this fraction. In contrast, Ni and Cr were found mainly in the residual fractions (50-80%). Finally, this biological treatment did not solubilize Cr appreciably, while removal of Ni mostly originated from the carbonate and Fe/Mn oxides fractions (70-80%).     

Heavy metal contamination of the soils used for stocking raw materials in the former ILVA iron-steel industrial plant of Bagnoli (southern Italy)

The total contents and the chemical and mineralogical forms of the metals Fe, Al, Cu, Co, Cr, Pb, Zn, Ni and Mn in the horizons of a soil profile, representative of an area devoted to stocking raw materials in the dismantled iron-steel industrial plant of ILVA of Bagnoli (Naples), were studied by physical and chemical methods. The geological setting of the study area is the result of volcanic activity in the Phlegrean Fields, a group of polygenic volcanoes to the west of Naples, which give rise to the parent soil material. Soil morphology appeared to be strongly disturbed by the occurrence and stratification of materials used in the industrial process. Fine sediments illuviation down the profile resulted in the occurrence of silt and clay coatings. The total contents of Cu, Co, Cr, Pb, Zn and Ni, in the whole soil samples, especially in the surface layers, were above the regulatory levels (Cu 120, Co 20, Cr 150, Pb 100, Zn 150, Ni 120 mg kg(-1)) stated by the Italian Ministry of Environment for soils in public, private and residential areas, and below the levels (Cu 600, Co 250, Cr 800, Pb 1000, Zn 1500, Ni 500 mg kg(-1)) outlined for soils and subsoils of industrial and commercial areas (Gazzetta Ufficiale della Repubblica Italiana, 1999). Speciation of heavy metals and the determination of the different chemical pools in the fraction < 2 mm identified the large presence of elements trapped in the mineralogical structure of oxides and silicates and occluded in easily reducible manganese or iron oxides. A constant amount of Cu was associated with organic compounds. A significant amount of Zn (> 20%) was extracted in diluted acetic acid solution, indicating that the element was present in a more readily and potentially available form. In the clay fraction (< 2 microm) heavy metals were associated with both amorphous and crystalline iron forms. The presence of iron-rich clay coatings was evident in the illuvial pores of deeper horizons. Enrichment in Cu, Co, Cr and Zn of the coatings was observed. Possible translocation of metals down through the soil profile mainly bound to fine particles of relatively inert forms of iron is hypothesised. The dispersion in water of the clay fraction resulted in an average percentage dispersion of approximately 20% with a peak of 41.7% at 68-72 cm depth. Magnetite, goethite, hematite, calcite and quartz mixed with K-feldspars, clynopyroxenes and mica occurred in the coarse sand fractions (2-0.2 mm) of the soil samples from all the surface horizons. Talcum and goethite together with clay minerals at 1.4 nm, kaolinite and illite were found in the clays (< 2 microm).     

Metal content of dandelion (Taraxacum officinale) leaves in relation to soil contamination and airborne particulate matter.

The global distribution of the common dandelion (Taraxacum officinale Weber, sensu lato; Asteraceae), along with its ability to tolerate a wide range of environmental conditions, make this 'species' a particularly attractive candidate to evaluate for its value as a biological monitor of environmental metal contamination. To examine the metal content of dandelion leaves in relation to environmental metal levels, the concentrations of eight metals (Cd, Cr, Cu, Fe, Mn, Ni, Pb and Zn) were analyzed in leaf and soil samples collected at 29 sites in the mid-western United States differentially impacted by pollution. Sites were chosen primarily to cover a range of annual mean 24-h airborne particulate matter < or = 10 microm (hereafter, PM10) exposure, with PM10 levels varying from those found in isolated rural areas to levels typical of the most industrialized urban locations in the mid-western United States. A positive. significant correlation was detected between soil concentrations of each metal and measures of PM10 at a site, signifying that airborne particulate matter is a good indicator of soil metal contamination. Leaf concentrations of four of the eight metals (Cr, Mn, Pb and Zn) examined were found to increase significantly as the soil levels of these metals increased, but the percentage of the total variation explained by the relationship in these cases was generally low. This latter finding, along with the lack of a significant relationship between leaf and soil concentrations for the four other metals, indicate that the factors affecting metal absorption from the soil by dandelions are complex and that, aside from soil metal concentrations, other soil, plant and/or other environmental factors affect metal uptake. There was also no evidence that leaf metal concentrations were positively correlated with PM10. In addition, the concentrations of some metals (Cu, Fe, Mn, Pb and Zn) were significantly higher in leaves collected in the fall compared to those collected at the same sites in the spring. These findings suggest that dandelions may not be a particularly effective tool for quantifying levels of environmental metal contamination, at least on the scale of pollution typifying industrialized urban areas of the mid-western United States.     

The distribution and dynamics of chromium and nickel in cultivated and uncultivated semi-arid soils from Nigeria

Growing concern about heavy metal contamination of agricultural lands under long-term application of inorganic fertilizers and organic wastes makes periodic risk assessment of heavy metal accumulation in arable lands imperative. As a part of a much larger study to systematically document the status of heavy metals in savanna soils this study investigated the distribution and dynamics of Cr and Ni in a savanna soil after 50 years of continuous cultivation and application of inorganic fertilizers and organic manures. The cultivated fields were fertilized with inorganic fertilizers (NPK), farmyard manure (FYM), FYM+NPK for 50 years and a control plot under continuous cultivation for 50 years but did not receive either FYM or NPK. Two uncultivated or natural sites were sampled as reference conditions for assessing the dynamics of Cr and Ni induced by cultivation and management practices. The distribution of Cr and Ni in the soil profiles exhibited eluvial-illuvial patterns. Sand and clay fractions explained between 62 and 90% of the variance in Cr and Ni concentration and distribution in the soil profiles. Mean Cr concentrations ranged from 17 to 59 mg kg(-1), while Ni varied from <1 mg kg(-1) in the topsoil to 16 mg kg(-1) in the subsoil. Mass balance calculations showed a loss of 10% Cr and 17% Ni in the FYM field, and approximately 4% Cr and 11% Ni in the NPK field compared to the natural site after 50 years of cultivation. The control and FYM + NPK field had, however, a positive balance of Cr and Ni. In general, it was concluded that existing soil management practices in this region are unlikely to lead to Cr and Ni build-up probably because of low rates of application of inorganic fertilizers, farmyard manure and other organic wastes to the soils.     

Microbes influence the fractionation of arsenic in paddy soils with different fertilization regimes

Sequential extraction procedures were used to investigate the influence of the microbes on the distribution of arsenic in a Chinese paddy soil under different long-term fertilization treatments. The paddy soil with four long-term fertilization treatments (CK, M, NPK and NPK + M) and three levels of arsenate addition (0, 50, 100 mg As kg^− 1 dry soil), were selected to construct microcosms for laboratory incubation. After the incubation, soil samples were sequentially extracted to determine As in various fractions, i.e. water soluble (F0), exchangeable (F1), bound to carbonates (F2), bound to Fe and Mn oxides (F3), bound to organic matter and sulfides (F4), and residual (F5, mineral matrix). Results showed that most of the As was fixed by mineral matrix (F5, ratios ranging from 46.22% to 96.37%), followed by As bound to Fe and Mn oxides (F3, ratios ranging from 3.14% to 28.18%), and the ratios of the other four fractions (F0, F1, F2 and F4) were mostly less than 10%. The microbes in the paddy soil could make As transform from inactive fraction (F5) to relatively active fractions (F0, F1, F2 and F3) and thus increase its environmental risk. With the increase of the As addition levels and with the application of manure or chemical NPK fertilizers, As was distributed more in the relatively active fractions (F0, F1, F2, F3 and F4) in the paddy soil mediated by the microbes. In addition, Fe and Mn oxides could play an important role in decreasing the As leaching potential from the mineral matrix to soil solution and thus abate the As risk to human health.     

Assessing risk to human health from tropical leafy vegetables grown on contaminated urban soils

Fifteen tropical leafy vegetable types were sampled from farmers' gardens situated on nine contaminated sites used to grow vegetables for commercial or subsistence consumption in and around Kampala City, Uganda. Trace metal concentrations in soils were highly variable and originated from irrigation with wastewater, effluent discharge from industry and dumping of solid waste. Metal concentrations in the edible shoots of vegetables also differed greatly between, and within, sites. Gynandropsis gynandra consistently accumulated the highest Cd, Pb and Cu concentrations, while Amaranthus dubius accumulated the highest Zn concentration. Cadmium uptake from soils with contrasting sources and severity of contamination was consistently lowest in Cucurbita maxima and Vigna unguiculata, suggesting these species were most able to restrict Cd uptake from contaminated soil. Concentrations of Pb and Cr were consistently greater in unwashed, than in washed, vegetables, in marked contrast to Cd, Ni and Zn. The risk to human health, expressed as a ‘hazard quotient’ (HQ_M), was generally greatest for Cd, followed successively by Pb, Zn, Ni and Cu. Nevertheless, it was apparent that urban cultivation of leafy vegetables could be safely pursued on most sites, subject to site-specific assessment of soil metal burden, judicious choice of vegetable types and adoption of washing in clean water prior to cooking.     

Application of high Cu compost to Swiss chard and basil

A greenhouse container experiment was conducted to evaluate the effect of high Cu compost on basil and Swiss chard productivity, and the accumulation of As, Ca, Fe, Hg, K, Mg, Na, Cd, Co, Cr, Cu, Mn, Mo, Ni, Pb, S and Se in growth medium and plant tissue. The Cu content of the compost was over 1200 mg/kg, much higher than Canadian standards for type B compost quality. The treatments consisted of control soil (0% compost), and 20, 40 and 60% (by volume) of high Cu compost added to soil. All compost application treatments (20, 40 and 60%) resulted in increased dry matter yields in Swiss chard and basil. Addition of high Cu compost influenced basil plant development. Plants from the 20 and 40% treatments had higher numbers of buds and flowers. There were no differences between the control and 60% compost treatments with respect to flower initiation. Addition of 20, 40 and 60% compost to the soil resulted in increased EXCH fractions of Cu, but not of Mn and Zn. Compost additions resulted in increase in the HNO(3) extractable, CARB, FeMnOX, and in OM fractions of Cu, Mn and Zn in soils. Compost application increased soil pH and EC, soil HNO(3) extractable Ca, K, Mg, P, Na, B and Pb, but did not alter soil HNO(3) extractable Cd, Co, Cr, Mo, Ni, Se. Increased rates of compost application decreased tissue Ca in basil, tissue Na in both plants, increased tissue K, Mg in both plants, but, did not alter tissue P, Co, Cr, Mo, Ni of either plants, and B in basil. Tissue As, Hg, Pb, and Se from all treatments were under the detection limits of VGA-AAS (for As, Hg, Se) and ICP (for Pb). Compost additions altered basil oil chemical composition. Copper in the essential oil of basil was below 0.25 mg/l. In conclusion, the addition of high rates of relatively immature high Cu compost may not always increase Cu concentration in plants and in plant oils.     

Heavy metal pollution associated with mining activity in the Kouh-e Zar region,NE Iran

The Kouh-e Zar mining area is located in the central part of the “Khaf–Bardaskan” volcanic-plutonic zone, NE Iran. Mining activity has resulted in pollution of soil and water resources by potentially toxic elements including arsenic (As), cadmium (Cd), chromium (Cr), copper (Cu), antimony (Sb), nickel (Ni) and zinc (Zn). In this study, the major source of heavy metal pollution and elucidating the probable environmental risks associated with this area were determined by quantifying pollution in soils and water resources. Concentrations of Cd, Cr, Cu, Pb and Zn in the Kouh-e Zar mining area varied in the range of 5–470, 33–442, 25–5125, 81.15–12,096.27 and 55–4210 mg/kg, respectively. The geo-accumulation index for Cd in all samples was extremely high (I_geo > 5) and the enrichment factor also shows an extremely high amount (EF > 40), both representing evidence for highly polluted soil in the area. However, the coefficients of aqueous migration (K_x) of Cd, Cr, Cu, Pb and Zn were K_x < 0.1, so they are classified as “least mobile and inert” grade. Also, the heavy metals tend to remain in soil (solid environment). Cluster analysis (CA) determined the lithogenic origin for Zn, Cu, Cr and Cd, and the anthropogenic origin (mining activity) for Pb in the soils of the mining area. The concentrations of Cd, Cu, Pb and Zn in water are controlled by free Fe and Mn oxy-hydroxide content in the soils. Both water–rock interaction and mining activity have contributed to pollution in the area.

     

Arsenic solubility and distribution in poultry waste and long-term amended soil

The purpose of this study was to quantify the solubility and distribution of As among solid-phase components in poultry wastes and soils receiving long-term poultry waste applications. Arsenic in the water-soluble, NaOCl-extractable (organically bound), NH(2)OH x HCl-extractable (oxide bound) and residual fractions were quantified in an Upper Coastal Plain soil (Neshoba County, MS) that received annual waste applications. After 25 years, As in the amended soil had a mean of 8.4 mg kg(-1) compared to 2.68 mg kg(-1) for a non-amended soil. Arsenic in the amended soil was mainly in the residual fraction (72% of total), which is generally considered the least bioavailable fraction. Arsenic in poultry waste samples was primarily water-soluble (5.3-25.1 mg kg(-1)), representing 36-75% of the total As. To assess the extent of spatial heterogeneity, total As in a 0.5-ha area within the long-term waste-amended field was quantified. Soil surface samples were taken on 10-m grid points and results for total As appeared negatively skewed and approximated a bimodal distribution. Total As in the amended soil was strongly correlated with Fe oxides, clay and hydroxy interlayered vermiculite concentrations, and negatively correlated with Mehlich III-P, mica and quartz contents.     

Metal phase associations in soils from an urban watershed, Honolulu, Hawaii

Soils of Manoa watershed, Hawaii, have received varying inputs of anthropogenic trace metals, with roadside soils primarily influenced by automobile contributions. A four-stage sequential extraction procedure was used to fractionate 13 topsoil (0-2.5 cm) and 13 subsoil (7.5-10.0 cm) samples into: (i) an adsorbed, exchangeable and carbonate (AEC) phase; (ii) a reducible phase; (iii) an oxidizable phase; and (iv) a residual phase. Phases (i)-(iii) were considered 'labile', with the residual fraction 'non-labile' under normal circumstances. An examination of eight elements (Al, Co, Cu, Fe, Mn, Ni, Pb and Zn) indicated that Pb was the trace metal most impacted by anthropogenic inputs. Roadside soil Pb enrichment was apparent with data from a 0.5 M HCI leach exhibiting a maximum concentration of 1000 mg/kg compared with a median background value of 12 mg/kg. Sequential extraction results indicated the following order with respect to phase dominance for Pb: reducible > residual > oxidizable > AEC. The identification of the reducible phase as the primary pool of available Pb supports previous work from temperate roadside soil environments. The reducible phase is characterized by hydrous Fe and Mn oxides and mobilization of fixed elements can occur with decreases in pH and redox potential. Iron was the least labile of the elements examined with only 5-6% of total Fe removed by the first three steps of the extraction procedure. Lead had the highest labile percentage with average values between 74 and 81%. Therefore, results from this study support earlier research in this watershed which identified Pb as the primary trace metal of concern from a contamination perspective.     

Mobile and bound forms of trace metals in sediments of the lower ganges

Mobile and bound trace metals associated with sediment components (viz. exchangeable, carbonate, organic, Fe/Mn oxide and residual fractions) were determined at five locations on the River Ganges in the lower reaches. In the exchangeable phase, 5–22% of Pb, 5–14.4% of Cr, 3–16.4% of Cd, 3–16% of Zn and 1–13.5% of Cu were found, and in the carbonate phase 73–87% of Zn, 38–41% of Cd, 13–27% of Ni and 3–10.1% of Pb were found. The Fe/Mn oxide phase retained about 79–83% of Mn, 30–40% of Cr and Fe, 22–25% of Cu, 14–16% of Ni and 9–11% of Pb. In the organic phase about 36–47% of Cd, 22–28% of Cu and 10–15% of Pb were found. The order of release of metals was Cd > Cr > Pb > Cu > Zn > Ni > Mn > Fe, and the order of adsorption characteristics of most of the mobile metal fractions was Fe/Mn oxide > organic > clay. Correlations of the physico-chemical parameters with adsorption characteristics were also determined and a good correlation (r = 0.7) of cation exchange capacity with the clay fraction was found. I_geo (geoaccumulation indices) of metals in the sediments were also evaluated. Results showed a considerable enrichment of trace metals in the sediment phase at almost all the sites.     

Application of waste ashes to agricultural land--effect of incineration temperature on chemical characteristics

Incineration is one of the most important methods of municipal waste disposal. During incineration, various reactions of composition and decomposition may occur; the physical and chemical properties of municipal wastes may change to a great extent. In the present study, 15 samples, including food scraps (FS), animal wastes (AW) and sewage sludges (SS) were collected from various places in Japan, incineration treatments at 500 degrees C, 850 degrees C and 1000 degrees C were conducted in laboratory, and pH, EC, P content, various P forms, anions and soluble metals were determined. The results indicated that average pH increased by 1.09, 1.84, 2.27 and EC decreased by 4.6, 4.6, 5.6 ds m(-1) at 500 degrees C, 850 degrees C, 1000 degrees C, respectively, pH increased in the sequence of AM > SS > FS, and the decrease rate of EC was in the order of FS > SS > AM. Compared with no treatment (NT), water-soluble P decreased greatly at all three temperatures; available P increased at 500 degrees C, but decreased to the original level at 850 degrees C and 1000 degrees C; the amount of Ca-P, Fe-P and Al-P decreased and residual insoluble P increased greatly at 850 degrees C and 1000 degrees C; no significant change of total P was found at all three temperatures. However, water-soluble HPO4(2-) and Cl- decreased greatly, the decrease ratio of Cl- was in the sequence of SS > FS > AM at 500 degrees C, and FS > SS > AM at 850 degrees C and 1000 degrees C; no significant difference was found for HPO4(2-) among all three treatment temperatures; water-soluble SO4(2-) decreased at 1000 degrees C, but there was no significant change at 500 degrees C and 850 degrees C. Moreover, water-soluble Na, Mg, K, Ti, Mn, Fe, Ga, Cd, Zn, Ba, Pb, Sr, W and 0.1 M HNO3 soluble Al, K, Cr, Mn, Fe, Zn, Sr, Ba, Pb, Be, Ga, Rb, Cd, Sn, Sb, Ta, Tl, Bi, Na, Co, Ni, Sc, Cs decreased, but water-soluble Ca, Cr, Co, Ni and 0.1 M HNO3 soluble Cu, Ca, V, Mo, W, Th, U, Hf increased at 500 degrees C, 850 degrees C or 1000 degrees C.     

Concentrations of selected metals in honey consumed in Nigeria

The concentration of metals, cadmium (Cd), lead (Pb), nickel (Ni), chromium (Cr), copper (Cu), cobalt (Co), iron (Fe), manganese (Mn), and zinc (Zn) was measured in selected samples of honey in Nigeria with a view to providing information on the regional concentration profile of metals in these honeys. The honey samples were digested with a mixture of acids and analysed for metal concentrations using atomic absorption spectrophotometry. The concentrations of metals (mg kg^?1) in these honeys ranged from < 0.3 for Cd,<0.50–39.75 for Pb,<0.25–6.98 for Ni,<0.25–55.25 for Cr,<0.25–71.25 for Cu,<0.25–3.50 for Co,<5.0–163.15 for Fe,<11.0–31.75 for Mn and 1.0–31.0 for Zn. The concentrations of metals were relatively high but lower than their respective permissible limits in food except for Pb and Cu in some samples. The regional distribution patterns of metals indicated that honey samples from the Niger Delta region of Nigeria had higher mean concentrations of Ni, Cr, Co, Fe and Zn than honey samples from other regions. The honey samples from the northern region had higher mean concentrations of Pb and Cu.     

Mass balance and distribution of sludge-borne trace elements in a silt loam soil following long-term applications of sewage sludge

Soil samples were collected at 15-cm increments to a depth of 75 cm from plots on a silt loam soil where until several years earlier and for 14 years, anaerobically digested sewage sludge had been annually applied by furrow irrigation. The study protocol consisted of four replications of 6.1 x 12.2-m plots with 0 (T0), 1/4-maximum (T1), 1/2-maximum (T2) and maximum (T3) sludge application rates randomized within blocks. When sludge applications were terminated, maximum sludge-treated plots had received 765 Mg ha-1 (dry weight equivalent) of sludge solids. Total soil concentrations of Cd, Cr, Cu, Ni, Pb and Zn had been significantly enhanced by all sludge application rates to a soil depth of 30 cm. Below the 30-cm depth, total soil Cd was increased to 75 cm, total Zn to 45 cm (T2 and T3 only), total Cr to 60 cm (T2 and T3 only), but total Cu, Pb, and Ni were not increased at depth. Despite the lack of significant increases in subsoil concentrations for some metals, mass balance calculations showed a relatively high proportion of all the above sludge-borne heavy metals to be unaccounted for in the soil profile for each application rate. Mass balance calculations of losses ranged from a high of 60% for Ni to a low of 36% for Cu and Pb. Similar losses were calculated from metal concentrations measured in soil samples taken at the time the sludge was applied. In soil surface samples (0-15 cm) from maximum sludge-treated plots, percentages of total metal concentration extracted with 4.0 M HNO3 ranged from a low of 31 for Zn to a high of 75 for Cu. Efficiency of metal extraction by HNO3 was inconsistent, depending on the soil horizon and sludge treatment, so that evaluation of HNO3-extractable metals is not a reliable method of estimating total metal retention in the profiles. In soil surface samples from maximum sludge-treated plots, the percentage of total metal contents extracted with DTPA ranged from a low of 0.03 for Cr to a high of 59 for Cd. The DTPA extractable levels of Cu, Ni, and Pb were higher in the subsoils of the sludge-treated soils, indicating that these metals had been redistributed from the surface layer to deeper zones in the profile of sludge-amended soil, despite the absence of elevated total concentrations of these three metals in the deeper subsoil.     

Quantities and associations of lead, zinc, cadmium, manganese, chromium, nickel, vanadium, and copper in fresh Mississippi delta alluvium and New Orleans alluvial soils

The topic of this study is the effect of anthropogenic metals on the geochemical quality of urban soils. This is accomplished by comparing the metal contents and associations between two alluvial soils of the lower Mississippi River Delta, freshly deposited alluvial parent materials and alluvial soils collected from a nearby urban environment. Fresh alluvium samples (n = 97) were collected from the Bonnet Carré Spillway. The urban alluvial soil samples (n = 4026) were collected from New Orleans and stratified by census tracts (n = 286). The Spillway samples tend to have less Pb and Zn than generally noted for the baseline of natural soils. Except for Mn and V, Spillway alluvium contains significantly less metal than urban soils. For Spillway samples, the median metal content (in microg g(-1)) is 4.7 Pb, 11.1 Zn, 0.7 Cd, 164 Mn, 0.8 Cr, 3.9 Ni, 3.2 V, and 3.9 Cu. For urban soils, the median metal content (in microg g(-1)) is 120 Pb, 130 Zn, 3.2 Cd, 138 Mn, 2.1 Cr, 9.8 Ni, 3.8 V, and 12.7 Cu. Metal associations also differ between Spillway alluvium and urban alluvial soils. Fresh alluvium correlation coefficients between individual metals vary from 0.87 to 0.99 (P < 10(-13)) except for Cr which ranges from 0.57 to 0.68 (P < 10(-7)). The urban soil correlation coefficients for metals and the index value are 0.40-0.98. In urban soils, Pb, Zn, Cr, and Cu are dominant metals and highly associated, with a correlation coefficient ranging from 0.83 to 0.98 (P < 10(-25)). Their strong association justifies the use of GIS to map the integrated soil metal index (sum of the medians of metals by census tract) of New Orleans. Although also positively correlated (0.40-0.68, P < 10(-10)), Cd, Mn, Ni and V differ in their distribution in the city compared to Pb, Zn, Cr and Cu. Overall, significantly higher metal values occur in the inner city and lower values occur in outlying areas. The human health impact of the mixture of metals is not well understood. This study provides empirical data about the mixture and distribution of metals in New Orleans alluvial soils. Given common technical development, especially of traffic flows in cities, similar patterns of soil metals are expected for all US cities and probably international cities as well. Primary prevention of urban metal accumulations is necessary to enhance and sustain the development of urban culture.     

Metal Accumulation In Sediments Of The Exclusive Economic Zone Of Qatar,Persian Gulf

The EEZ of Qatar is subjected to different landbased sources and marine activities. Twenty-three sediment samples were collected from the EEZ of Qatar, Persian Gulf and analyzed to determine the effect of increasing man-made activities on the structure and chemical composition of seabed. Grain size analysis support the predominance of sand sized sediments with patches of sandy silt at the northeastern and southeastern areas. Coarse grained sand was characterized by elevated carbonate content reaching >95%. Off the capital Doha and opposite to industrial parks, the organic matter reached >7.4%. Cu (0.8-30.3 r w g/g), Pb (2.2-22.6 r w g/g), Co (2.4-9.1 r w g/g) and Mn (36.8-746 r w g/g) levels were high compared to other Gulf values. Stations were clustered on the basis of sediment texture rather than metal accumulation. The high organic content of northeastern sediments, derived from planktonic origin is coupled by low metals concentrations. Except for Cr, Cu and Fe, the non-residual fraction of metals contributed between 56 and 92% of the total metals concentrations. Stations sampled closer to potential metal sources are characterized by increased non-residual fractions. Negligible or very low amount (<5%) of the non-residual fraction of metals appeared in the exchangeable phase. Metals are mostly associated with the easily and moderately reducible fraction (23% Fe, 17% Cr, 24% Co, 34% Mn, 14% Ni and 18% Cu) due to strong scavenging capabilities of Fe-Mn oxides. Pb is partitioned equally among easily/moderately reducible and carbonate fractions, dominating in the latter. Co (38%) and Ni (35%) are mostly associated with organic matter/sulphide phase, while Zn (27-29%) is equally partitioned between easily/moderately reducible, carbonate and organic matter phases. Cr (73%), Cu (62%) and Fe (58%) appeared mainly in the residual form. The concentrations of bioavailable metal fractions (exchangeable and easily/moderately reducible) do not put at risk the economically important living resources.     

The use of lichen (Cetraria nivalis) and moss (Rhacomitrium lanuginosum) as monitors for atmospheric deposition in Greenland

Concentrations of Pb, Cd, Hg, Zn, Cu, Cr, Ni, As, V, Al and Fe are reported from soil, humus, moss (Rhacomitrium lanuginosum) and lichen (Cetraria nivalis) sampled at four locations in Greenland. For Al, Fe, Cr and V the levels in soil were highest followed by humus and R. lanuginosum and with the lowest levels in C. nivalis. The same was true for Pb, Cu and Ni but without as great a difference between medias. For Cd and Hg, the lowest levels were found in soil. For Zn and As, the media with highest levels differed between locality. Data were examined by a principal component analysis. Three principal components explained 87% of the total variation. The dominant elements in the first component were Fe, Al, V, Ni, Cr, Cu and Pb. This component is interpreted as a soil dust factor. The concentrations in R. lanuginosum and C. nivalis of these elements are believed to be highly influenced by soil dust. Pb concentrations in moss and lichen may also be influenced by other sources as Pb also had some correlation's with the third component. Zn and Cd and to a lesser extent. As were the dominant elements in the second component. The third component was highly dominated by Hg with a lesser influence of Pb and As, Zn, Cd and Hg concentrations in R. lanuginosum and C. nivalis are believed to be influenced by other sources than soil dust which may be long-range atmospheric transport. In general, both the within locality and the between locality variability in the values of the three components decreased in the order soil, humus, R. lanuginosum and C. nivalis. The lichen C. nivalis is looked at as an indicator with greater potential for monitoring atmospheric deposition of elements than the moss R. lanuginosum.     

Efficiency of a continuous deflective separation (CDS) unit in removing contaminants from urban stormwater

The weighted average concentration (WAC) of total suspended solids (TSS) in stormwater effluent from a continuous deflective separation (CDS) unit in Port Jackson (Australia) catchment was reduced by an average 28% during six high-flow events, but some TSS was released during turbulent, high-flow events. The average removal efficiency of metals Cr, Cu, Pb Mn, Ni, Zn and Fe varied considerably (?49% for Pb and +10% for Mn), whereas Ni and Zn were inefficiently removed by the device. Average concentrations of TKN, NO_x and TP were similar at both in- and out-flow points and faecal coliforms counts were slightly reduced.