Growth of Vetiveria zizanioides and Phragmities australis on Pb/Zn and Cu mine tailings amended with manure compost and sewage sludge: a greenhouse study

The Lechang lead/zinc (Pb/Zn) mine and Dabao Shan copper (Cu) mine are located at the north of Guangdong Province in southern China. The residual tailings were permanently stored in tailings ponds which required revegetation to reduce their impact on the environment. A greenhouse study was conducted to evaluate the feasibility of using Vetiveria zizanioides (vetiver) and Phragmities australis (common reed) for the reclamation of Pb/Zn and Cu mine tailings and to evaluate the effects of organic amendments using manure compost (11.00, 22.03, 44.05 and 88.10 t/ha) and sewages sludge (11.00, 22.03, 44.05 and 88.10 t/ha) on the revegetation of these tailings. The results revealed that the applications of manure compost or sewage sludge not only increased N, P and K concentrations, but also decreased DTPA-extractable Pb and Zn contents in Pb/Zn tailings and DTPA-extractable Cu contents in Cu tailings. For Pb/Zn mine tailings, application of sewage sludge increased the yields of both species (highest yield at 44.05 t/ha), but not manure compost. For Cu mine tailings, application of manure compost (highest yield for both species at 44.05 and 22.03 t/ha for vetiver and common reed accordingly) or sewage sludge (highest yield at 22.03 and 44.05 t/ha for vetiver and common reed accordingly) increased the yield of both species. In general, vetiver achieved a higher yield when compared with common reed, under the same treatment. Plant tissue analysis showed that application of manure compost and sewage sludge could significantly reduce Pb uptake and accumulation, but not Cu in both vetiver and common reed.     

Amendment-assisted revegetation of mine tailings: improvement of tailings quality and biomass production

Abstract

Mining activities have left a legacy of metals containing tailings impoundments. After mine closure, reclamation of mine wastes can be achieved by restoration of a vegetation cover. This study investigated the impact of biochar (BC), biosolids (BS), humic substances (HS), and mycorrhizal fungi (MF) for improving mine tailings fertility and hydraulic properties, supporting plant establishment, tailings revegetation, and enabling growth of energy crops. We conducted a pot trial by growing willow, poplar, and miscanthus in Pb/Zn/Cu mine tailings untreated or amended with two rates of amendments (low or high input). Biosolids resulted in the most significant changes in tailings properties, neutralizing pH and increasing organic carbon, nutrient concentrations, cation exchange capacity, water retention, and saturated hydraulic conductivity. The greatest increase in energy crops production was also observed in BS treatments enabling the financial viability of mine reclamation. Although BC resulted in significant improvements in tailings fertility and hydraulic properties, its impact on biomass was less pronounced, most likely due to lower N and P available concentrations. Increases in willow and miscanthus biomass were observed in HS and MF treatments in spite of their lower nutrient content. A pot experiment is underway to assess synergistic effects of combining BS with BC, HS, or MF.     

Effects of earthworm (Pheretima sp.) on three sequential ryegrass harvests for remediating lead/zinc mine tailings

Farm soil and artificial soil were mixed separately with Pb/Zn mine tailings and placed in the ratios (w/w) of 0, 12.5, 25, and 50% in pots, together with 0.33 g KH2PO4 and 0.35 g urea/pot. Each pot contained 15 ryegrass seedlings (Lolium multiflorum) and 7 earthworms (Pheretima sp.). At the end of the experiment (after the third harvests of ryegrass), the earthworms were all found to be alive and burrowed completely at the bottom of the pots in all treatments. Earthworm activity increased plant biomass significantly in artificial soil/tailings mixtures in the second and third harvests as compared with the control (without addition of earthworms), but not in the farm soil/tailings mixture. The biomass of ryegrass in both soil/tailings mixtures decreased with increase of tailings, especially those containing 50% tailings. In general, the plant biomass obtained from farm soil/tailings mixtures was lower than that from artificial soil/tailings mixtures. Earthworm activity did not significantly increase DTPA-extracted Zn or Pb, in both soil/tailings mixtures. However, the concentrations in farm soil/tailings mixtures were lower in the second and third harvests, compared with the first harvest. The Zn and Pb uptake by ryegrass shoots in the two soils/tailings mixtures did not increase significantly (compared with the control) in the first and second harvests. However, in the third harvest, Zn and Pb uptake increased significantly in farm soil/tailings mixtures, but decreased significantly in artificial soil/tailings mixtures (compared with the control). The results indicated that the presence of earthworms and sequential plant harvesting could be a viable strategy for the remediation of Pb/Zn tailings.     

Mobility and Translocation of Heavy Metals from Mine Tailings in Three Plant Species after Amendment with Compost and Biosurfactant

An experiment was performed to determine the effects of mine tailings alone mixed with compost or with compost plus crude biosurfactant on the accumulation of heavy metals (Pb, Zn, Cu, Cr, Cd, and Ni) in Acacia retinodes, Nicotiana glauca, and Echinochloa polystachya. The plants were grown in soil, mine tailings, and mine tailings containing compost over a period of seven and five months for shrubs or grass, respectively. The plants Acacia retinodes and Nicotiana glauca grown in mine tailings containing compost showed increases in dry biomass (from 62 to 79%) compared with plants in only tailings. Heavy metals accumulated in the roots and leaves showed high translocation rates of Cr in N. glauca, Cd in A. retinodes, and Ni in E. polystachya. Concentrations of heavy metals in the three plants irrigated with crude biosurfactant were not significantly different from those irrigated with water. Zn and Cd fractions within mine tailings containing compost were bound to carbonate, Pb was bound to residues, and Cu was bound to Fe-oxides. Cd had the highest mobility factor followed in order by Zn, Pb, and Cu. The elevated concentrations of Pb in roots and the low translocation rate for N. glauca and A. retinodes indicate that they are suitable for phytostabilizing Pb and Zn.     

VETIVER GRASS,VETIVERIA ZIZANIOIDES: A CHOICE PLANT FOR PHYTOREMEDIATION OF HEAVY METALS AND ORGANIC WASTES

Glasshouse and field studies showed that Vetiver grass can produce high biomass (>100t/tha^?1 year^?1) and highly tolerate extreme climatic variation such as prolonged drought, flood, submergence and temperatures (?15°–55°C), soils high in acidity and alkalinity (pH 3.3–9.5), high levels of Al (85% saturation percentage), Mn (578 mg kg^?1), soil salinity (ECse 47.5 dS m^?1), sodicity (ESP 48%), and a wide range of heavy metals (As, Cd, Cr, Cu, Hg, Ni, Pb, Se, and Zn). Vetiver can accumulate heavy metals, particularly lead (shoot 0.4% and root 1%) and zinc (shoot and root 1%). The majority of heavy metals are accumulated in roots thus suitable for phytostabilization, and for phytoextraction with addition of chelating agents. Vetiver can also absorb and promote biodegradation of organic wastes (2,4,6-trinitroluene, phenol, ethidium bromide, benzo[a]pyrene, atrazine). Although Vetiver is not as effective as some other species in heavy metal accumulation, very few plants in the literature have a wide range of tolerance to extremely adverse conditions of climate and growing medium (soil, sand, and tailings) combined into one plant as vetiver. All these special characteristics make vetiver a choice plant for phytoremediation of heavy metals and organic wastes.     

Phytoremediation of metals using lemongrass (Cymbopogon citratus (D.C.) Stapf.) grown under different levels of red mud in soil amended with biowastes

Due to hostile condition of red mud (RM), its utilization for vegetation is restricted. Therefore, RM with biowastes as soil amendment may offer suitable combination to support plant growth with reduced risk of metal toxicity. To evaluate the effects of RM on soil properties, plant growth performance, and metal accumulation in lemongrass, a study was conducted using different RM concentrations (0, 5, 10, and 15% w/w) in soil amended with biowastes [cow dung manure (CD) or sewage-sludge (SS)]. Application of RM in soil with biowastes improved organic matter and nutrient contents and caused reduction in phytoavailable metal contents. Total plant biomass was increased under all treatments, maximally at 5% RM in soil with SS (91.4%) and CD (51.7%) compared to that in control (no RM and biowastes). Lemongrass acted as a potential metal-tolerant plant as its metal tolerance index is >100%. Based on translocation and bioconcentration factors, lemongrass acted as a potential phytostabilizer of Fe, Mn, and Cu in roots and was found efficient in translocation of Al, Zn, Cd, Pb, Cr, As, and Ni from roots to shoot. The study suggests that 5% RM with biowastes preferably SS may be used to enhance phytoremediation potential of lemongrass.     

Effect of Organic Manures on the Growth of Cymbopogon citratus and Chrysopogon zizanioides for the Phytoremediation of Chromite-Asbestos Mine Waste: A Pot Scale Experiment

The abandoned chromite-asbestos mines are located in the Roro hills, West Singhbhum, Jharkhand, India, where mining operation ceased in 1983, and since then these mines are causing environmental pollution. The present study was planned to phytoremediate these metalloid and metal contaminated mine waste by using two aromatic grasses, Cymbopogon citratus and Chrysopogon zizanioides by applying different proportions of amendments (chicken manure, farmyard manure and garden soil). Mine waste has neutral pH, low electrical conductivity and organic carbon with higher concentration of total metals (Cr and Ni) as compared to soil. Application of manures resulted significant improvements of mine waste characteristics and plant growth, reduction in the availability of total extractable toxic metals (Cr, Ni) and increase in Mn, Zn and Cu concentration in the substrate. The maximum growth and biomass production for C. citratus and C. zizanioides were found in T-IV combination comprising of mine waste (90%), chicken manure (2.5%), farmyard manure (2.5%) and garden soil (5%). Addition of T-IV combination also resulted in low Cr and Ni accumulation in roots and reduction in translocation to shoots. Study indicates that C. citratus and C. zizanioides can be used for phytostabilization of abandoned chromite-asbestos mine waste with amendments.     

施用鸡粪对土壤与小白菜中Cu和Zn累积的影响

我国鸡饲养量已占世界总量的24%,鸡饲料添加剂中高含量的Cu和Zn随鸡粪排出体外,鸡粪作为优良的有机肥大量施用于菜园土壤,会导致土壤和蔬菜中重金属Cu和Zn的含量过高,进而通过食物链影响动物和人类健康。研究含高Cu和高Zn的鸡粪施入土壤后典型蔬菜对Cu和Zn的富集和转运,对于阐明鸡粪中Cu和Zn的土壤环境行为和蔬菜的健康风险评价具有重要的科学价值,同时可为蔬菜安全生产提供参考。本研究以Cu和Zn浓度分别为1137.3 mg/kg和1503.4 mg/kg的鸡粪堆肥作为实验材料,设置5个鸡粪施用处理,即11、22、44、89 g/kg和222 g/kg,相当于25、50、100、200 t/hm2和500 t/hm2,以不施鸡粪处理为对照。通过小白菜盆栽实验,研究了施用鸡粪对土壤与小白菜中Cu和Zn的影响。结果表明：土壤全Cu和全Zn含量范围分别为58.6—203.4 mg/kg和78.1—431.6 mg/kg;EDTA-Cu为12.7—119.8 mg/kg,EDTA-Zn为15.6—215.1 mg/kg。鸡粪施用量大于50 t/hm2时,土壤中Cu和Zn全量均较对照显著提高。小白菜地上、地下部以及整株Cu和Zn的含量都随鸡粪施用量的增加而提高,且地下部Cu、Zn的含量均高于地上部,同时小白菜各部分Zn的含量都高于Cu。鸡粪施用量大于100 t/hm2处理的小白菜地上部Cu含量显著高于对照处理,但是各处理小白菜中地上部的Zn含量与对照相比,均无显著性差异。施鸡粪量为大于50 t/hm2时,地下部分Cu含量较对照显著增加,而施鸡粪量大于100 t/hm2时,地下部分Zn含量显著增加。土壤有效态的Cu（EDTA-Cu）与植物各部分吸收Cu的相关性较好,但土壤有效态的Zn（EDTA-Zn）与植物各部分吸收Zn的相关性较差。随着鸡粪施用量的增加,小白菜对土壤中Cu的富集系数由11%增加到15%,对Zn富集系数却由47%下降到19%,小白菜对Cu和Zn的转运系数分别下降36%和51%。小白菜地上、地下部及整株的Zn/Cu都随鸡粪施用量的增加而减小,说明小白菜对Cu、Zn吸收转运能力的差异随着鸡粪施用量的增加而下降。     

Heavy metals in tissues of loggerhead turtles (Caretta caretta) from the northwestern Adriatic Sea

Thirty-five specimens of Caretta caretta were collected dead along the Adriatic Sea coast from the Po Delta to the Reno mouth (Italy). Turtles were classified into four size categories ranging from 24.5 to 74 cm, by measuring the minimum straight-line carapace length (MSCL). Cd, Cu, Fe, Mn, Ni, and Zn levels were assessed in liver, lung, muscle and adipose tissue. Cd, Cu and Fe mainly accumulated in the liver (8.9, 23.7 and 1180 mg/kg dry mass [d.w.], respectively), and Mn in the lung (29.5 mg/kg d.w.). Levels of Ni were higher in adipose (22 mg/kg d.w.) than other tissues, while Zn concentrations were higher in muscle (about 140 mg/kg d.w.). Negative correlations with size were established for Zn in liver and Cu in adipose tissue, while positive correlations were observed for Mn and Ni in adipose tissue. Metal concentrations did not differ between males and females, nor between individuals found stranded and those victims of by-catch. On average, Cd, Cu, Mn and Ni concentrations in our specimens were higher than in loggerhead turtles and other species living in other areas. We hypothesize that trace metals could be used as "acquired markers" to help investigate migration routes of C. caretta.     

CYCLING OF Mn,Fe, Cu AND Zn BY EELGRASS,ZOSTERA MARINA L

Significant (P < 0.005) differences in Mn, Fe, Cu and Zn concentrations were found in different parts of eelgrass plants; i.e., roots and rhizomes, live blades, attached dead blades, and detritus. Imported vs. exported suspended particles of eelgrass blades did not differ in Mn, Fe, Cu or Zn content. Significant location effects, which varied with the type of plant tissue, were noted for Mn, Fe, Cu and Zn for three grass beds in the vicinity of Beaufort, NC. In simplified Mn, Fe, Cu and Zn budgets, eelgrass biomass is the largest biological reservoir, while eelgrass growth, senescence, and decomposition constitute the largest biological flux of these elements in this ecosystem.     

多花黑麦草在酸化铅锌尾矿上的定植和生长

铅锌矿尾矿上设置长喙田菁压青和不压青处理,在此基础上研究多花黑麦草的萌发、生长和重金属积累情况．结果表明,种植长喙田菁改善了尾矿理化性状,尤其是提高了有机质、全N、有效态磷和K的含量．尾矿的强酸性环境(pH<3)是影响黑麦草在其上定植的主要因素．施用石灰可暂时改善尾矿酸度,但实验结束时尾矿酸度几乎完全恢复原状．因此,施用石灰可能只对种子发芽产生作用．大多数情况下多花黑麦草能在尾矿上萌发、生长和定植,并产生较大的生物量(DM1．4～3．2t·km^-2),表现出对酸性尾矿环境的一定的适应性．与未栽培长喙田菁的对照相比,栽培长喙田菁处理以及栽培长喙田菁并压青处理分别使多花黑麦草的生物量提高了4．8％～39．5％和7．7％～139．5％,其中压青处理又比不压青处理提高了2．7％～75．8％．“长喙田菁-多花黑麦草”植被系列是一个成功的铅锌矿尾矿废弃地复垦的先锋阶段     

Content of microelements in the grass shrimp pandalus kessleri (Decapoda: Pandalidae) from coastal waters of the Lesser Kurilskaya Ridge

The concentrations of Fe, Zn, Cu, Cd, Mn, Pb, and Ni were determined in the hepatopancreas, muscle tissue, and carapace of the grass shrimp Pandalus kessleri from the coastal waters of the Lesser Kurilskaya Ridge. Sex reversal of the grass shrimp, which is a proterandrous hermaphrodite, had a marked influence on the concentrations of such metals as Fe, Cu, Cd, and Mn. The levels of Cd in the hepatopancreas of grass shrimp exceeded maximum permissible concentrations for seafood at all the stations studied. The main factors determining the metal levels in P. kessleri from the investigated locations are discussed.     

Effects of sewage sludge application on heavy metal leaching from mine tailings impoundments

Column experiments were conducted to investigate the removal of heavy metals from two mine tailings (El Arteal and Jaravías) using sewage sludge as a reactive material. When sewage sludge is used as a reactive material on the El Arteal tailings (sample SA), Fe, Mn, Zn and Pb are removed and Cu and Ni are mobilized. The experiments carried out on the Jaravías tailings give similar results, showing the retention of Cu, Pb, Fe and Mn and the mobilization of Ni and Zn. An analysis performed using the PHREEQC numerical code suggests that the retention of Fe in the sewage sludge may be caused by the precipitation of Fe(OH)2.7Cl0.3 and possibly pyrite, and that the retention of Pb at high pH may be caused by the formation of stable phase minerals such as Pb(OH)2 and PbS in these conditions. Ni mobilization in the column experiments with the two tailings samples may be caused by the presence of significant amounts of leachable Ni in the sewage sludge. The complexation of metals with dissolved organic matter, calculated with the Minteq model, may be moderate.     

多花黑麦草在酸化铅锌尾矿上的定植和生长

铅锌矿尾矿上设置长喙田菁压青和不压青处理,在此基础上研究多花黑麦草的萌发、生长和重金属积累情况.结果表明,种植长喙田菁改善了尾矿理化性状,尤其是提高了有机质、全N、有效态磷和K的含量.尾矿的强酸性环境(pH<3)是影响黑麦草在其上定植的主要因素.施用石灰可暂时改善尾矿酸度,但实验结束时尾矿酸度几乎完全恢复原状.因此,施用石灰可能只对种子发芽产生作用.大多数情况下多花黑麦草能在尾矿上萌发、生长和定植,并产生较大的生物量(DM1.4～3.2t·km^-2),表现出对酸性尾矿环境的一定的适应性.与未栽培长喙田菁的对照相比,栽培长喙田菁处理以及栽培长喙田菁并压青处理分别使多花黑麦草的生物量提高了4.8%～39.5%和7.7%～139.5%,其中压青处理又比不压青处理提高了2.7%～75.8%.“长喙田菁多花黑麦草”植被系列是一个成功的铅锌矿尾矿废弃地复垦的先锋阶段.     

好氧高温猪粪堆肥中重金属砷、铜、锌的形态变化及钝化剂的影响

采用连续提取法研究了猪粪好氧堆肥处理中重金属浓度和形态的变化以及添加不同比例的重金属钝化剂对其浓度和形态的影响.结果表明：经过堆肥处理后,猪粪中重金属As、Cu和Zn的总浓度均有所增加.从重金属结合形态的变化来看,可交换态As和Zn含量降低,残渣态As和Zn含量升高,表明As和Zn存在着向有效性相对较低的形态转化的趋势;重金属Cu则表现出不同的变化趋势,即可交换态与残渣态Cu含量下降,而碳酸盐结合态、铁锰结合态及有机结合态Cu含量有所增加,在今后的堆肥利用中应注意其可能带来的环境风险;3种重金属钝化剂及不同添加比例的处理中,5.0%的海泡石和2.5%的膨润土分别对重金属As、Zn表现出较好的钝化效果,堆肥后残渣态As和Zn的增幅分别达到79.8%和158.6%,均高于不加钝化剂处理.与对照相比,堆肥后7.5%的海泡石对残渣态Cu的降低幅度最小,为39.3%.猪粪堆肥中添加适量的重金属钝化剂,可以在一定程度上降低重金属的有效性以及猪粪堆肥利用中重金属污染的风险.     

有机物料对污染土壤上水稻生长和重金属吸收的影响

采用盆栽试验,研究了施用有机碳源、菜籽饼和猪粪对污染土壤上水稻生长和重金属吸收特性的影响.结果表明： 施用菜籽饼和猪粪均能缓解重金属对水稻的毒害作用,促进水稻生长,显著增加地上部生物量和籽粒产量,降低糙米中重金属浓度;而有机碳源抑制水稻生长.与施用化肥相比,施用菜籽饼和猪粪处理的水稻籽粒产量分别增加128.3%和67.9%;施用菜籽饼处理的糙米Cd、Cu和Zn浓度分别降低47.6%、35.2%和21.5%,施用猪粪处理分别降低9.5%、21.2%和9.3%.土壤中DTPA提取态重金属浓度与水稻地上部生物量和重金属积累总量呈显著负相关.     

Effect of two biodegradable chelates on metals uptake,translocation and biochemical changes of Lantana Camara growing in fly ash amended soil

The present work had two purposes firstly to evaluate the potential of Lantana Camara for phytoextraction of heavy metals from fly ash amended soil and to assess the suitability of a proper biodegradable chelating agent for chelate assisted phytoextraction. Plants were grown in manure mixed soil amended with various concentration of fly ash. Two biodegradable chelating agents were added (EDDS and MGDA) in the same dose separately before maturation stage. Sampling was done at different growing stages. The plant took up metal in different plant parts in the following order: for Cu, and Zn leaf >root >stem, for Cr and Mn leaf>stem >root, for Ni root >leaf>stem and for Pb root≈leaf>stem respectively. For Cu, Zn, Cr and Mn Lantana camara acted as phytoextractor. Translocation factor and bioaccumulation coefficient was>1 signifying enrichment and translocation of metals in the plant. Morphological studies showed no toxicity symptom in the plant. Among biochemical parameters protein and nitrate reductase activity decreased, whereas, chlorophyll and peroxidise activity increased with the growth stages. Finally, it was evident from the results that Lantana Camara can be used as efficient phytoextractor of metals, with proper harvesting cycle and both chelate were proved as effective chelators for phytoextraction of metals.     

Some adverse effects of soil amendment with organic Materials—The case of soils polluted by copper industry phytostabilized with red fescue

The study was aimed to examine the effects of soil amendment with organic waste materials on the growth of red fescue and the uptake of Cu and Zn by this grass, in view of its potential usage for phytostabilization of Cu-polluted soils. Five soils, containing 301–5180 mg/kg Cu, were collected from the surroundings of copper smelter Legnica, and amended with lignite (LG) and limed sewage sludge (SS). Plant growth and the concentrations of Cu and Zn in the shoots and roots of grass were measured in a pot experiment and related to the results of Pytotoxkit and Microtox® tests performed on soil solution. The effects of soil amendment with LG and SS differed greatly, and depended on soil properties. In some cases, the application of alkaline SS resulted in dramatic increase of Cu phytotoxicity and its enhanced uptake by plants, while application of LG to slightly acidic soil caused increased accumulation of Zn in plants, particularly in their roots. The study confirmed good suitability of red fescue for phytostabilization of Cu-contaminated soils except for those extremely polluted. Organic amendments to be used for metal immobilization should be thoroughly examined prior to application.     

Classification of herbal mixtures on the basis of some metals content using pattern recognition techniques

The purpose of this study was to investigate the content of trace elements in relation to the composition of domestic herbal mixtures. Cluster analysis, principal components analysis, and self-organizing maps were applied to identify existing relationships. The concentrations of Ni, Pb, Cd, Cr, Cu, Fe, Mn, Zn in 81 samples of herbal mixtures were determined with application of FAAS. The study showed that the levels of trace elements in some herbal mixtures of the same composition were comparable. The projection of herbal samples onto topological maps of adjustable sizes allowed recognition of the identical herbal preparations characterized by dissimilar levels of trace elements. The elements which played the most important role in recognition of the herbal samples were Mn, Ni, Zn and partly Cu, Fe and Cd.     

Movement of water and heavy metals (Zn, Cu, Pb and Ni) through sand and sandy loam amended with biosolids under steady-state hydrological conditions

New guidelines for using biosolids in UK agriculture favour the use of enhanced treated biosolids, such as dried and composted cakes, due to concerns about the potential for transfer of pathogens into the food chain. However, there is a need to ensure that their use is environmentally acceptable and does not increase the risk to potable water supplies or the food chain from other contaminants such as heavy metals and xenobiotic organic chemicals. The objective of this study was to determine whether the use of composted and dried mesophilic anaerobically digested dewatered (MADD) biosolids would increase the risk of heavy metal leaching from cultivated horizons when compared to more conventionally used MADD cake. Three biosolids (MADD sewage sludge cake - fresh, dried and composted) were mixed with a sand (typic quartzipsamments, %OM = 3.0, pH = 6.5) or a sandy loam (typic hapludalf, %OM = 4.8, pH = 7.6) at an application rate equivalent to 250 kg N/ha/y resulting in loadings of approximately Zn: 6 microg, Cu: 2 microg, Pb: 5 microg and Ni: 0.2 microg/g of soil dry weight basis. These amended soils were repacked into columns (0.4 m by 0.1 m internal diameter) and leaching of Zn, Cu, Pb and Ni was investigated following application of two 24 h simulated rainfall events of 4.5 mm/h. Water balance data and the use of conservative tracers (Cl- and Br ) showed that the hydrological regimes of each core were comparable and, thus, unlikely to account for differences in metal leaching observed. Although no significant difference (P = 0.05) was observed between biosolid amended and control soils, those amended with composted sludge consistently gave higher loss of all metals than did the control soils. Total losses of metals from compost amended soil over the two rainfall events were in the ranges, Zn:20.5-58.2, Cu:9.0-30.5, Pb:24.2-51.2 and Ni:16.0-39.8 microg metal/kg amended soil, compared with Zn:16.4-41.1, Cu:6.2-25.3, Pb:16.9-41.7, and Ni:3.7-25.4 microg metal/kg soil from the control soils. Losses of Zn, Cu, Pb and Ni from fresh MADD cake amended soils (19.8-41.3, 3.2-25.8, 21.6-51.6 and 7.6-36.5 microg metal/kg amended soil, respectively) and from dry MADD cake amended soils (10.7-36.7, 1.8-23.8, 21.2-51.2 and 6.8-39.2 microg metal/kg amended soil, respectively) were similar to the controls. Generally, quantities of metals leached followed the order Zn = Pb > Cu > Ni, which was consistent with the levels of metals in the original sludge/soil mixtures. These results suggest that composting or drying MADD biosolids is unlikely to increase the risk of groundwater contamination when compared to the use of MADD cake; therefore, the changes in UK sludge use in agriculture guidelines are satisfactory in this respect.