Accumulation Of Heavy Metals In Soil Research Articles

Accumulation of heavy metals in sunflower and sorghum plants affected by the Guadiamar spill

The collapse of a pyrite-mining, tailing dam on 25 April 1998 contaminated approximately 2000 ha of croplands along the Agrio and Guadiamar river valleys in southern Spain. This paper reports the accumulation of chemical elements in soil and in two crops — sunflower and sorghum — affected by the spill. Total concentrations of As, Bi, Cd, Cu, Mn, Pb, Sb, Tl and Zn in spill-affected soils were greater than in adjacent, unaffected soils. Leaves of spill-affected crop plants had higher nutrient (K, Ca and Mg for sunflower and N and K for sorghum) concentrations than controls, indicating a ‘fertilising’ effect caused by the sludge. Seeds of spill-affected sunflower plants did accumulate more As, Cd, Cu and Zn than controls, but values were below toxic levels. Leaves of sorghum plants accumulated more As, Bi, Cd, Mn, Pb, Tl and Zn than controls, but these values were also below toxic levels for livestock consumption. In general, none of the heavy metals studied in both crops reached either phytotoxic or toxic levels for humans or livestock. Nevertheless, a continuous monitoring of heavy metal accumulation in soil and plants must be established in the spill-affected area.

Copper and zinc adsorption by sewage sludge‐treated soil in southern Spain

Heavy metal accumulation in soil due to the application of sewage sludge may induce changes in its ionic retention capacity. In this work, sludge application effects on copper (Cu) and zinc (Zn) adsorption by the surface horizon of a calcareous soil in Southern Spain have been studied. Sludge from the urban waste water treatment plant in Cordoba was applied at rates of 0,40, and 80 Mg sludge ha‐1 for two consecutive years. Despite the low metal content of this sludge and the high amount of organic matter added, a decrease in the soil adsorption levels for both Cu and Zn was detected in the sludged samples. Differences were observed, though, in the behavior of each metal, relative to the main adsorption mechanism involved. Copper adsorption was related to carbonate surfaces in soil. Values up to 400 mmol adsorbed Cu kg‐1 soil were obtained for the three treatments, in equilibrium with 13.6, 16.7, and 17.4 mmol Cu m‐3 in solution for 0, 40, and 80 Mg sludge ha‐1, respectively, the first year, and 13.9, 21.2, and 52.2 mmol Cu m‐3 in solution the second year. However, an increase of soil Cu availability is not likely to arise during or after continuous application of these sludge doses, due to the high calcium carbonate content of this soil. In the case of Zn, adsorption took place in CEC sites, with values up to 40 mmol adsorbed Zn kg‐1 soil in the 0 and 80 Mg sludge ha‐1 samples, in equilibrium with 158.3 and 164.5 mmol Zn m3 in solution, respectively the first year, and 196.1 and 505.8 mmol Zn m3 in solution the second year, whereas in the 40 Mg sludge ha‐1 samples adsorption was below 25 mmol Zn kg‐1 soil, in equilibrium with 171.1 mmol Zn m3 in solution the first year, and 231.0 mmol Zn m‐3 the second year. As soil CEC values and its organic matter content are positively related, Zn availability in this soil could be expected to increase after the cessation of sludge applications, due to the mineralization of the organic matter added.

99/00541 Profitability of willow cultivation for energy production in Finland

Land application of residues in short-rotation plantation has a priori the double advantage to meet the nutrient needs of these tree plantations at lower cost while recycling residues. Agronomic and environmental effects of a very wide variety of residues on plants and soils have been studied worldwide. I attempt here to compile and to summarize the results of the studies about the effects of land applications of residues (mostly organic) in plantations or under controlled pot conditions of the three species mostly used for short-rotation coppice: willow, poplar, and eucalyptus. The spreading of most residues causes an enrichment of the soil in nutrients and a subsequent increase in the growth of plants. Manure, compost, sewage sludge, and wastewater seem most effective in stimulating growth. Ashes have less impact on growth. Few negative effects on the plant have been highlighted in response to spreading, except in the case of very rich effluents in salt in response to which growth reduction and leaf loss nevertheless did not lead to plant death. The high transpiration potentials of the fast growing species dedicated to intensive tree plantations allow them to absorb and tolerate, without major damages, nutrients in excess, most heavy metals, and antibiotics. In some cases, heavy metal accumulation in soils following the spreading of residues, but few of them showed leaching or water pollution. Nevertheless, the used doses and the intervals between applications were of primary importance to avoid leakage of undesirable elements in the environment.

Calculating heavy metal accumulation in soil: a comparison of methods illustrated by a case-study on compost application

Accumulation of heavy metals in agricultural soil can be prevented by achieving an input that is smaller than, or equal to, the output. This is known as the ‘balance approach’. Heavy metal balance sheets can be used to determine the contribution of different input and output flows to the resulting accumulation. The change in heavy metal content in the plough layer is the result of the net difference between input and output flows per unit time. Existing balance approaches lack an analysis of the effect of soil amendments on soil composition. However, soil composition determines soil bulk density and plough layer weight and, hence, the resulting change in heavy metal concentration. It is, therefore, important to understand and account for the processes that affect soil composition. Recycling of compost produced from source-separated organic household waste as a soil amendment in agriculture is used as an example to illustrate how changes in soil composition complicate accumulation calculations. The dynamic soil composition balance approach is presented as a way to handle these complications by calculating mass balances of both heavy metals and main soil constituents. Comparing results of the dynamic soil composition balance with those of other balance approaches reveals the necessity to account for changes in soil composition and for the effect of soil-bound heavy metal flows in calculating heavy metal accumulation in agricultural soil. This new balance approach is of special relevance if organic soil amendments (e.g., manure and compost) and soil-bound heavy metal flows (e.g., erosion) are involved.

Heavy Metal Accumulation in Soil Associated with Long-Term Application of Sewage Sludge Compost

Heavy Metal Accumulation in Soil Associated with Long-Term Application of Sewage Sludge Compost

Ecological evaluation of long-term application of sewage sludges according to the legislative permissions

In Germany the recycling of biogenic municipal wastes, for instance sewage sludge, as carriers of plant nutrients and organic substance in agriculture is promoted by recently published regulations. Limits for maximum application rates as well as for tolerable contents of unwanted contaminants are laid down in these regulations.The published results on effects of long-term application of sewage sludge on heavy metal accumulation in soils and their bio-transfer into the food-chain are, almost without exception, based on experiments with application rates and heavy metal contents of sewage sludge that exceed more or less these limits. Therefore, as far as the ecological value of agricultural utilization of sewage sludge within the valid frame is concerned, they lead to wrong conclusions. This is demonstrated by the results of a long-term sewage sludge treatment (1962–1992) in accordance with the actual limits on application rates as well as heavy metal contents from the very start of the experiment. After thirty years of sewage sludge application no significant influence on the heavy metal contents of the soil could be detected, although there was a tendency of slight increase in values. Furthermore, compared to the control with mineral fertilization, there was no significant effect on the heavy metal contents of wheat (grain) and ryegrass. However, both mineral fertilization and sewage sludge resulted in a significant increase in the Cd content of the test plants but on a very low and ecologically irrelevant level.

Effect of sewage sludge on nodulation and N2−fixation in alfalfa grown on calcareous loamy soils

AbstractThe influence of different rates of sludge applications to calcareous loamy soils of Saudi Arabia, on nodulation and symbiotic N2−fixation in alfalfa plants (Medicago sativa L.) was studied in a pot experiment. The effect of heavy metals accumulation in soil due to continuous irrigation of the test soil with sewage water was also investigated. Application of up to 80 g sludge per pot enhanced nodulation, nitrogenase activity, dry matter yield and N‐contents of alfalfa plants growing in loamy soils either previously irrigated with sewage water or well water. However, sludge applied at the rate of 160–200 g pot−1 inhibited the nodulation, N accumulation and dry matter yield of alfalfa. The response of alfalfa to sludge was dependent on the rhizobial strain used. Our results also showed that accumulation of heavy metals due to continuous irrigation of a calcareous sandy loam soil with sewage water, for more than 10 years, didn't inhibit N2−fixation in alfalfa plants, but enhanced it. Microelements in alfalfa plants increased with increase in the rate of sludge application. Although high rates of sludge application affected nodulation and N2−fixation of alfalfa, dry matter and the nitrogen contents of the plants were not highly affected. Therefore, the inhibitory effect of high rates of sludge was most probably due to the toxic effect of heavy metals on the microsymbiont rather than on the plants.

Retention and distribution of heavy metals in mangrove soils receiving wastewater

The distribution and chemical fractionation of heavy metals retained in mangrove soils receiving wastewater were examined by soil column leaching experiments. The columns, filled with mangrove soils collected from two swamps in Hong Kong and the People's Republic of China, were irrigated three times a week for 150 days with synthetic wastewater containing 4 mg l −1 Cu, 20 mg l −1 Zn, 20 mg l −1 Mn and 0.4 mg l −1 Cd. Soil columns leached with artificial seawater (without any heavy metals) were used as the control. At the end of the leaching experiments, soil samples from each column were divided into five layers according to its depth viz. 0–1, 1–3, 3–5, 5–10 and > 10 cm, and analyzed for total and extractable heavy metal content. The fractionation of heavy metals in the surface soil samples (0–1 cm) was investigated by the sequential extraction technique. In both types of mangrove soils, the surface layer (0–1 cm) of the columns receiving wastewater had significantly higher concentrations of total Cu, Cd, Mn and Zn than the control. Concentrations declined significantly with soil depth. The proportion of exchangeable heavy metals in soils receiving wastewater was significantly higher than that found in the control, about 30% of the total heavy metals accumulated in the soil masses of the treated columns were extracted by ammonium acetate at pH 4. The sequential extraction results show that in native mangrove soils (the soils without any treatment), the major portion of Cu, Zn, Mn and Cd was associated with the residual and precipitated fractions with very low concentrations in more labile phases. However, in mangrove soils receiving wastewater, a significantly higher percentage of Mn, Zn and Cd was found in the water-soluble and exchangeable fractions. Copper appeared to be more strongly adsorbed in mangrove soils than the other heavy metals. In general, heavy metal accumulation in the surface mangrove soils collected in Hong Kong was higher than those in the PRC, although the metals in the latter soil type were more strongly bound. These findings suggest that whether the heavy metal retained in managrove soils becomes a secondary source or a permanent sink would depend on the kinds of heavy metals and also the types of mangrove soils.

Modelling and monitoring organochlorine and heavy metal accumulation in soils, earthworms, and shrews in Rhine-delta floodplains.

In the Rhine-delta, accumulation of microcontaminants in floodplain foodwebs has received little attention in comparison with aquatic communities. To investigate organochlorine and metal concentrations in a terrestrial foodchain, samples of soil, earthworms (Lumbricus rubellus), and shrew (Crocidura russula, Sorex araneus) livers and kidneys were taken from two moderately to heavily polluted floodplains. Chlorobiphenyl residues in earthworm fat were 0.10 to 3.5 times the concentrations in soil organic matter, whereas ratios for other organochlorines varied between 0.87 and 8.8. These ratios are one order of magnitude lower than expected from laboratory experiments with earthworms, and laboratory and field studies on aquatic invertebrates. Bioconcentration ratios for heavy metals are in accordance with literature values for other locations, confirming the high potential for cadmium accumulation in Lumbricidae. Concentrations of organochlorines in shrew liver lipids were 1.0 to 13 times the residues in earthworm fat. These values are higher than lipid-corrected biomagnification ratios for laboratory rodents, but equal to those measured for benthivorous birds in the Rhine-delta. On a dry weight basis, kidney-earthworm ratios for cadmium were about one order of magnitude lower than previously reported values for insectivores. Soil concentrations of many compounds in both floodplains did not meet Dutch quality standards. Yet, hexachlorobenzene, chlorobiphenyl 153 (PCB153), gamma-hexachlorocyclohexane, sigma DDT, and dieldrin residues in earthworms and shrews did not exceed diet levels expected to be safe for endothermic species. An exception was noted for cadmium in worms and shrew kidneys. Heavy metal pollution in soil was close to levels that are critical to earthworms in laboratory studies. Cadmium concentrations in shrew kidneys were below levels suggested to be safe for Sorex araneus, but above those that were critical to the rat.

Effects of land application of waste water from Mexico City on soil fertility and heavy metal accumulation: a bibliographical review

Waste water from Mexico City metropolitan area has been used to irrigate the Mezquital Valley since 1912. This zone is nowadays the largest area under this situation. Mexico City's drainage is a water mixture emanating from different sources: household, industries, commerce, rain, and runoff. Waste waters used in the valley have greatly increased crop yields. Owing to the increase in the country's industrial development, since the seventies several studies have been carried out in this area, especially related to metal content in water, soils, and crops. The aim of this paper is to present a bibliographical review of the effects of Mexico City's waste water land application on soil fertility and heavy metal accumulation. Pb, Cd, Cu, and Zn levels in soils and crops at present do not represent risks, but there is a clear tendency for these metals to accumulate in the upper layers of soils. Salt content in waste water is intensifying soil salinization in impeded drainage areas. The local conditions of soil, such as high levels of organic matter and high pH values, seem to be preventing the solubility of heavy metals, and hence their transportation or absorption by crops.Key words: heavy metals, waste water irrigation, Mexico City, nutrients, environment, pollutants.

Environmental impact of wastewater irrigation in central Mexico: An overview

The current knowledge on the environmental impact and public health risks associated with wastewater irrigation in central Mexico is summarized and discussed. Wastewater reuse in that semiarid region represents a valuable resource in agricultural production, due to the irrigation supply and considerable nutrients input to the farming soil. Nevertheless, there is evidence of increased prevalence of parasitic infections among agricultural workers and their families exposed to raw wastewater irrigation. Negative environmental effects may result from long‐term wastewater application, due to heavy metal accumulation in soils, increasing amounts of immediately mobile and easily mobilizable metal fractions, as well as crops uptake. First investigations carried out on soil fertility suggest the occurrence of important nitrogen losses, which could represent potential risks to public health induced by elevated nitrate concentrations in groundwater. Emphasis is given on future research priorities and measures that h...

Content of some heavy metals in soil and corn grain

Abstract In an attempt to find causes for lower than expected corn (Zea mays L.) production along the bottomlands of the Green and Pond Rivers in western Kentucky, corn fields were sampled for soil and corn grain to determine heavy metal content. Samples from sixteen carefully selected fields were analyzed for Cd, Cr, Pb, and Ni content. Yield of corn was not related to either soil or grain content of these heavy metals. There was also no relationship between soil pH and heavy metal accumulation by grain or heavy metal accumulation by grain and soil content of heavy metals within the range of levels found. Soil contents of Cr, Pb, and Ni were within the range of values reported in the literature for uncontaminated soils. However, soil content of Cd was near or above the upper end of the ranges reported in the literature, even on control samples taken upstream from sites of potential heavy metal pollution. Karnak soils (fine, montmorillonitic, nonacid, mesic Vertic Haplaquepts), which are high in montmoril...

Effect of repeated phosphate fertilization on the heavy metal accumulation in soil and plants under protected cultivation

Abstract In order to study the effects of repeated phosphate fertilization under protected cultivation, tomato (Lycopersicon esculentum Mill.), radish (Raphanus sativus L.), celery (Apium graveolens L.), and lettuce (Lactuca sativa L.) plants were grown in subsequent cycles on the same substrate and fertilized with increasing amounts of superphosphate containing varying amounts of heavy metals. The accumulation of metals in the soil and the consequent increased uptake of metals by plants did not result in any reduction in the marketable production. The reduced plant yield observed in lettuce and in radish with the increase in the addition of superphosphate was most likely due to the increased salinity of the growth substrate, which affected the metabolic processes of the plants. The high concentration of salts as a result of the addition of high amounts of phosphorus fertilizer made it unadvisable to reuse the substrate under the experimental conditions adopted.

Uptake by corn and chemical extractability of heavy metals from a four year compost treated soil

This paper gives the results from four-year field experiments on compost application, added at the maximum rate allowed by Italian legislation (30 t/ha/y). The purpose of the experiment was to evaluate any eventual heavy metal accumulation in soil and corn plants. Cadmium in corn plants increased particularly in the roots from 0.22 mg kg−1 to 1.31 mg kg−1, concentration of Zn and Cu increased in grains, from 26.8 to 35.8 and from 2.4 to 4.2 mg kg−1 respectively. Relevant increase in the roots was detected for Zn from 34.6 to 146.8 mg kg−1. Only in the 4th year Ni concentration increases in the root portion while the content of Pb and Cr in corn was generally unaffected by the compost application. Heavy metals in the soil determined by a sequential chemical extraction, indicated that extractability changed with time. A certain increase was found from the beginning to the end of the experiment particularly for Zn, from 23.3 mg kg−1 to 45.1 mg kg−1 in extractable forms. Nevertheless the extractable amounts are rather small in respect to the total heavy metal content of compost.

Influence of prolonged use of sewage effluent in irrigation on heavy metal accumulation in soils and plants

AbstractTotal content of Fe, Mn, Zn, Cu, Pb, Cd, Ni and Co in soils irrigated with sewage effluent increased with increasing years of using sewage effluent in irrigation. Iron and Co applied to the soil from sewage effluent were immobilized mainly in unavailable form; Pb, Cd, and Ni in moderately available form; and Mn, Zn, and Cu in highly available form. The concentrations of Fe, Mn, Zn and Cu in tops of alfalfa and leaves of corn grown on these soils increased substantially with increased levels of available metal content of the soil, while those of other metals were little affected. As for orange, continuous increase in leaves metal content with time was found for Fe, Mn, Zn, Co and Cd. The concentrations of Cd, Co, Ni and Pb in corn grains and orange fruits were several times higher than normal, and this reduces their suitability for human consumption.

Irradiated digested sewage sludge: Effects on plant-symbiont associations in the field

Anaerobically digested sewage sludge was irradiated with high energy electrons as a means of disinfestation at Boston's Deer Island Treatment Facility and transported to the Suburban Experiment Station of the University of Massachusetts, at Waltham. In May 1977, it was applied to limed field plots as liquid surface applications. Three plots were given a single application at the rate of 4·7 metric tonnes/ha dried sludge. Three other plots received double this amount (9·4 metric tonnes/ha). Three additional plots served as controls and received 111 kg/ha each of 10-10-10 N, P, K inorganic fertiliser. These applications were repeated with the same plots in May 1978. In both 1977 and 1978 sludge applications at both rates inhibited rhizobial nodulation of bush bean Phaseolus vulgaris L. ‘Contender’ and VA mycorrhizal infection in onion Allium cepa L. ‘Downing Yellow Globe’. Heavy metal accumulation in soil and plant tissue, pH, soluble salt levels and N and P status of sludge and soil were monitored throughout the experiment as possible explanations for these inhibitions. No readily discernible explanation was found.