Effects of mycorrhizae and other soil microbes on revegetation of heavy metal contaminated mine spoil

The effects of mycorrhizal fungi and other soil microorganisms on growth of two grasses, Andropogon gerardii Vitm. and Festuca arundinacea Schreb., in heavy metal-contaminated soil and mine tailings were investigated. A. gerardii is highly dependent on mycorrhizal fungi in native prairie, while F. arundinacea is a facultative mycotroph and relies on mycorrhizal symbiosis only in extremely infertile soils. Regardless of microbial amendments, neither plant species was able to establish and grow in the mine tailings. Both plant species grew in the moderately contaminated or non-contaminated soils, although A. gerardii grew in these soils only when mycorrhizal. Other soil microbes significantly improved growth of A. gerardii only in uncontaminated soil, but to a lesser extent than mycorrhizae. Although F. arundinacea was more highly colonized by mycorrhizal fungi than A. gerardii, neither microbial amendment affected growth of fescue in any soil. In several treatments mycorrhizal fungi adapted to uncontaminated soil stimulated plant growth more than mycorrhizae adapted to the moderately contaminated soil. However, mycorrhizal fungi adapted to contaminated soil did not increase the productivity of plant growth in contaminated soil more than fungi adapted to uncontaminated soil. A. gerardii plants inoculated with mycorrhizal fungi retained more Zn in roots than in shoots, confirming earlier reports that mycorrhizal fungi alter the translocation pattern of heavy metals in host plants. In contrast, mycorrhizae did not affect translocation patterns in F. arundinaceae, suggesting that the mycorrhizal dependence of a plant species is correlated with the retention of metals in roots. The correlation between mycorrhizal dependence of a plant species and mycorrhizal alteration of translocation pattern may also explain the inconsistent reports of mycorrhizal effects on translocation of heavy metals in plants. Plant response to mycorrhizal symbiosis may therefore provide a useful criterion for the selection of the plant species to be used in revegetation of contaminated sites.     

Testing nickel tolerance of Sorghastrum nutans and its associated soil microbial community from serpentine and prairie soils

Ecotypes of Sorghastrum nutans from a naturally metalliferous serpentine grassland and the tallgrass prairie were assessed for Ni tolerance and their utility in remediation of Ni-polluted soils. Plants were inoculated with serpentine arbuscular mycorrhizal (AM) root inoculum or whole soil microbial communities, originating from either prairie or serpentine, to test their effects on plant performance in the presence of Ni. Serpentine plants had marginally higher Ni tolerance as indicated by higher survival. Ni reduced plant biomass and AM root colonization for both ecotypes. The serpentine AM fungi and whole microbial community treatments decreased plant biomass relative to uninoculated plants, while the prairie microbial community had no effect. Differences in how the soil communities affect plant performance were not reflected in patterns of root colonization by AM fungi. Thus, serpentine plants may be suited for reclamation of Ni-polluted soils, but AM fungi that occur on serpentine do not improve Ni tolerance.     

Assessment of the applicability of a “toolbox” designed for microbially assisted phytoremediation: the case study at Ingurtosu mining site (Italy)

The paper describes the fieldwork at the Italian test site of the abandoned mine of sphalerite and galena in Ingurtosu (Sardinia), with the aim to assess the applicability of a “toolbox” to establish the optimized techniques for remediation of soils contaminated by mining activities. A preliminary characterization—including (hydro)geochemistry, heavy metal concentration and their mobility in soil, bioprospecting for microbiology and botany—provided a data set for the development of a toolbox to deliver a microbially assisted phytoremediation process. Euphorbia pithyusa was selected as an endemic pioneer plant to be associated with a bacterial consortium, established with ten selected native strains, including metal-tolerant bacteria and producers of plant growth factors. The toolbox was firstly assessed in a greenhouse pot experiment. A positive effect of bacterial inoculum on E. pithyusa germination and total plant survival was observed. E. pithyusa showed to be a well-performing metallophyte species, and only inoculated soil retained a microbial activity with a high functional diversity, expanding metabolic affinity also towards root exudates. These results supported the decision to proceed with a field trial, investigating different treatments used singly or in combination: bioaugmentation with bacterial consortia, mycorrhizal fungi and a commercial mineral amendment. Microbial activity in soil, plant physiological parameters and heavy metal content in plants and in soil were monitored. Five months after the beginning, an early assessment of the toolbox under field conditions was carried out. Despite the cold season (October–March), results suggested the following: (1) the field setup as well as the experimental design proved to be effective; (2) plant survival was satisfactory; (3) soil quality was increased and bioaugmentation improved microbial activity, expanding the metabolic competences towards plant interaction (root exudates); and (4) multivariate analysis supported the data provided that the proposed toolbox can be established and the field trial can be carried forward.     

Rhizoremediation of pentachlorophenol by Sphingobium chlorophenolicum ATCC 39723

Sphingobium chlorophenolicum is well known as a pentachlorophenol (PCP) degrader. The objective of this study was to evaluate PCP degradation in a loamy sandy soil artificially contaminated with PCP using phytoremediation and bioaugmentation. Measurements of PCP concentrations were carried out using high performance liquid chromatography analyses (HPLC). The toxic effect of PCP on plants was studied through the monitoring of weight plant and root length. The biodegradation of PCP by S. chlorophenolicum in soil was assessed with a bioluminescence assay of Escherichia coli HB101 pUCD607. Bacterial analyses were carried out by plating on Mineral Salt Medium (MSM) for S. chlorophenolicum, MSM for PCP-degrading/tolerant organisms and Trypticase Soy Broth Agar (TSBA) for heterotrophic organisms. The introduction of S. chlorophenolicum into soil with plants showed a faster degradation when compared to the non-inoculated soil. The monitoring of the plant growth showed a protective role of S. chlorophenolicum against the toxicity of PCP. The bioassay confirmed that initial toxicity was lowered while degradation progressed. There was a significant increase of organisms tested in the roots in comparison to those in the soil. This study showed that the presence of S. chlorophenolicum enhanced the PCP degradation in a loamy soil and also it had a protective role to prevent phytotoxic effects of PCP on plant growth. The combined use of bioaugmentation and plants suggests that the rhizosphere of certain plant species may be important for facilitating microbial degradation of pesticides in soil with important implications for using vegetation to stabilize and remediate surface soils.     

Plant accumulation of potentially toxic elements in sewage sludge as affected by soil organic matter level and mycorrhizal fungi.

Leek (Allium ameloprasum) was grown in pot trials in two clay loams of contrasting organic contents, with and without indigenous mycorrhizal propagules. Sewage sludges containing varying levels of Cd, Cu and Zn were added. Extractable soil metals, plant growth, major nutrient content and accumulation of metals, and soil microbial indices were investigated. The aim was to establish whether soil organic content and mycorrhizal status affected plant and microbial exposure to these metals. Extractable metals were higher and responses to inputs more pronounced in the arable, lower organic matter soil, although only Cd showed a soil difference in the CaCl2 fraction. There were no metal toxic effects on plants and some evidence to suggest that they promoted growth. Uptake of each metal was higher in the larger plants of the grassland, higher organic matter soil. Inoculation with arbuscular mycorrhizal fungi increased root Cd and Zn concentrations. With the exception of Cd (roots) and Zn (shoots), higher inputs of sludge metals did not increase plant metals. Zn and Cu, but not Cd, concentrations were higher in roots than in shoots.     

Potential of different species for use in removal of DDT from the contaminated soils

Dichlorodiphenyltrichloroethane (DDT) and its main metabolites, p,p'-DDD and p,p'-DDE (DDTs in this study included DDT, DDD and DDE), are frequently detected in agricultural soils even though its usage in agriculture was banned in 1980s or earlier. In this study, eleven plants including eight maize (Zea mays) cultivars and three forage species (alfalfa, ryegrass and teosinte) widely cultivated in China were grown in the soils spiked with DDTs to investigate their potential for removal of DDT from the contaminated soils. The plants varied largely in their ability to accumulate and translocate DDTs, with the bioconcentration factor (BCF; DDT concentration ratio of the plant tissues to the soils) ranging from 0.014 to 0.25 and the translocation factor (TF; DDT concentration ratio of the shoots to the roots) varying from 0.35 (Zea mays cv Chaotian-23) to 0.76 (Zea mays spp. mexicana). The amount of DDT phytoextraction ranged from 3.89mug (ryegrass) to 27.0mug (teosinte) and accounted for <0.1% of the total initial DDTs spiked in the soils. After 70d, the removal rates reached 47.1-70.3% of the total initial DDTs spiked in the soils with plants while that was only 15.4% in the soils without plant. Moreover, the higher removal rates of DDTs occurred at the first 20d of experiment, and then the removal rate decreased with time. The highest amount of DDTs phytoextracted was observed in teosinte, followed by Zea mays spp. mexicana, but the highest removal rate of DDTs was found in maize (Zea mays cv Jinhai-6). Even though phytoextraction is not the main removal process for DDTs, the plant species especially Zea mays cv Jinhai-6 showed high potential for removing DDTs from the contaminated soils.     

In situ fixation of metals in soils using bauxite residue: biological effects

Soils polluted with heavy metals can cause phytotoxicity and exhibit impared microbial activities. In this paper we evaluate the responses of different biological endpoints to in situ remediation processes. Three soil amendments (red mud, beringite and lime) were applied to two soils polluted by heavy metals. Oilseed rape, wheat, pea and lettuce were grown successively in pots on the untreated and amended soils and their yield and metal uptake were determined. A suite of microbial tests (lux-marked biosensors, Biolog and soil microbial biomass) were performed to determine the effect of the soil amendments on the functionality and size of the soil microbial community. In both soils all three amendments reduced phytotoxicity of heavy metals, enhanced plant yields and decreased the metal concentrations in plants. The red mud treatment also increased soil microbial biomass significantly. The microbial biosensors responded positively to the remediation treatments in the industrially-contaminated soil used in the experiment. Red mud applied at 2% of soil weight was as effective as beringite applied at 5%. The results also showed that since the biological systems tested respond differently to the alleviation of metal toxicity, a suite of biological assays should be used to assess soil remediation processes.     

Uptake of metals by food plants grown on soils 10 years after biosolids application

Potentially hazardous trace elements such as Cd, Cu, Cr, Ni and Zn are expected to accumulate in biosolids–amended soil and remain in the soil for a long period of time. In this research, uptake of metals by food plants including cabbage, carrot, lettuce and tomato grown on soils 10 years after biosolids application was studied. All the five metals were significantly accumulated in the biosolids-amended soils. The accumulation of metal in soil did not result in significant increase in concentrations of Cu, Cr and Ni in the edible plant tissues. However, the Cd and Zn concentrations of the edible tissues of plants harvested from the biosolids receiving soils were significantly enhanced in comparison with those of the unaffected soils. The plant uptake under Greenfield sandy loam soil was generally higher than those under the Domino clayey loam soil. The metal concentration of edible plant tissue exhibited increasing trends with respect to the concentrations of the ambulated metals. The extents of the increases were plant species dependent. The indigenous soil metals were absorbed by the plants in much higher rates than those of the biosolids–receiving soils. It appeared that the plant uptake of the indigenous soil-borne metal and the added biosolids-borne metals are independent of one another and mathematically are additive.     

Health risks of heavy metals in contaminated soils and food crops irrigated with wastewater in Beijing, China

Consumption of food crops contaminated with heavy metals is a major food chain route for human exposure. We studied the health risks of heavy metals in contaminated food crops irrigated with wastewater. Results indicate that there is a substantial buildup of heavy metals in wastewater-irrigated soils, collected from Beijing, China. Heavy metal concentrations in plants grown in wastewater-irrigated soils were significantly higher (P相似文献   

Improvement of soil characteristics and growth of Dorycnium pentaphyllum by amendment with agrowastes and inoculation with AM fungi and/or the yeast Yarowia lipolytica

The effectiveness of two microbiologically treated agrowastes [dry olive cake (DOC) and/or sugar beet (SB)] on plant growth, soil enzymatic activities and other soil characteristics was determined in a natural soil from a desertified area. Dorycnium pentaphyllum, a legume plant adapted to stress situations, was the test plant to evaluate the effect of inoculation of native arbuscular mycorrhizal (AM) fungi and/or Yarowia lipolytica (a dry soil adapted yeast) on amended and non-amended soils. Plant growth and nutrition, symbiotic developments and soil enzymatic activities were limited in non-amended soil where microbial inoculations did not improve plant development. The lack of nodules formation and AM colonization can explain the limited plant growth in this natural soil. The effectiveness and performance of inocula applied was only evident in amended soils. AM colonization and spores number in natural soil were increased by amendments and the inoculation with Y. lipolytica promoted this value. The effect of the inoculations on plant N-acquisition was only important in AM-inoculated plants growing in SB medium. Enzymatic activities as urease and protease activities were particularly increased in DOC amended soil meanwhile dehydrogenase activity was greatest in treatments inoculated with Y. lipolytica in SB added soil. The biological activities in rhizosphere of agrowaste amended soil, used as indices of changes in soil properties and fertility, were affected not only by the nature of amendments but also by the inoculant applied. All these results show that the lignocellulosic agrowastes treated with a selected microorganism and its further interaction with beneficial microbial groups (native AM fungi and/or Y. lipolytica) is a useful tool to modify soil physico-chemical, biological and fertility properties that enhance the plant performance probably by making nutrients more available to plants.     

Response of kidney bean to concentration and chemical form of cadmium, zinc, and lead in polluted soils

Seven soils which had been polluted with heavy metals from a zinc smelter were sequentially extracted so that Cd, Zn, and Pb could be partitioned into five operationally defined geochemical fractions: exchangeable, carbonate, Fe-Mn oxide, organic, and residual fractions. Kidney beans were planted in the soils to examine the effect of concentration and chemical form of the metals in soil on the growth and metal uptake of the plants. The growth of kidney bean was restricted in heavy metal polluted soils compared with controls. Metal concentration and metal uptake by plants were correlated. The highest relationship was found between amount of metal uptake and the metal concentration in exchangeable + carbonate forms. The uptake of metals was according to their solubility sequence, i.e. Cd > Zn > Pb. The uptake rate of exchangeable + carbonate forms was the same for the three elements.     

Enhanced phytoextraction of an agricultural Cr- and Pb-contaminated soil by bioaugmentation with siderophore-producing bacteria

Bioaugmentation-assisted phytoextraction may enhance the phytoextraction efficiency thanks to larger metal mobilization by microbial metabolites. Green fluorescent protein-tagged cells of Pseudomonas aeruginosa, Pseudomonas fluorescens or Ralstonia metallidurans, able to produce siderophores, were inoculated in an agricultural soil containing Cr (488 mg kg(-1)) and Pb (382 mg kg(-1)) and maize was cultivated. Bacteria were inoculated as free or immobilized cells in Ca-alginate beads, with skim milk in the aim at improving both the bacterial survival and the in situ siderophore production. Skim milk addition increased inoculated Pseudomonads concentration in soil. Soil inoculation with free cells of R. metallidurans supplied with skim milk increased Cr accumulation in maize shoots by a factor of 5.2 and inoculation with immobilized P. aeruginosa cells supplied with skim milk increased Cr and Pb uptake by maize shoots by a factor of 5.4 and 3.8, respectively. However total metal taken up by the whole plant decreases almost always with bioaugmentation. Translocation factor also increased with P. aeruginosa or R. metallidurans by a factor of 6 up to 7. Inoculated bacteria concentration in soil was correlated with metals in the exchangeable fraction. Cr and Pb concentrations in the exchangeable fraction were correlated with metal contents in shoots or roots. Our results suggest that bioaugmentation-assisted phytoextraction is a relevant method in the aim at increasing the phytoextraction rate which usually limits the use of phytoremediation technologies.     

Uptake of carbamazepine by cucumber plants--a case study related to irrigation with reclaimed wastewater

Reclaimed wastewater is an important source of irrigation in semiarid and arid zones. Here we report data on carbamazepine (CBZ) uptake by cucumber plants in hydroponic culture and greenhouse experiments using different soil types irrigated with fresh water or reclaimed wastewater. Data obtained from the hydroponic culture experiments suggest that CBZ is mainly translocated by water mass flow, and thus it is concentrated and accumulated to the largest extent in the mature/older leaves. Carbamazepine concentration in cucumber fruits and leaves was negatively correlated with soil organic matter content. The concentrations of CBZ in the roots and stems were relatively low, and most CBZ in the plant (76-84% of total uptake) was detected in the leaves. A greenhouse experiment using fresh water and reclaimed wastewater spiked, or not, with CBZ at 1 μg L⁻¹ (typical concentration in effluents) revealed that CBZ can be taken up and bioaccumulated from its background concentration in reclaimed wastewater. Bioaccumulation factor (calculated as the ratio of CBZ concentration in the plant to that in the soil solution) for the fruits (0.8-1) was significantly lower than the value calculated for the leaves (17-20).This study emphasizes the potential uptake of active pharmaceutical compounds by crops in organic-matter-poor soils irrigated with reclaimed wastewater and highlights the potential risks associated with this agricultural practice.     

Differential bioavailability of field-weathered p,p'-DDE to plants of the Cucurbita and Cucumis genera

Field experiments were conducted to assess the bioavailability of weathered p,p'-DDE in soil to plants in the Cucurbita (squash, pumpkin) and Cucumis (cucumber, melon) genera. As expected, significant variability exists in the uptake of p,p'-DDE between plants of different genera. Root:soil concentration factors, defined as the ratio of p,p'-DDE (ng/g, dry weight) in the roots to that in the soil, approach 1.8 for cucumbers/melons and 16 for squash/pumpkin. However, significant differences were also observed among varieties of squash and pumpkin, with greater than an order of magnitude variation in the root:soil concentration factors and up to two orders of magnitude difference in the absolute amount of contaminant present within the plant. Although root systems routinely contain the highest concentration of p,p'-DDE (ng/g), this compartment comprises less than 2% of the total plant biomass. In all varieties but one, more than 86% of the extracted pollutant was in the shoot system. For two of varieties of Cucurbita pepo, concentrations of p,p'-DDE in the stems reached 1.1-2.2 mg/g and estimations of percent contaminant extraction from the soil ranged from 0.40% to 2.4%. These values approach those observed in the phytoremediation of heavy metals by "hyperaccumulating" species and indicate the potential for a plant-based remediation approach to soils contaminated with persistent organic pollutants.     

Distribution and availability of arsenic in soils from the industrialized urban area of Beijing, China

Concentrations of arsenic (As) were determined in soils of 5 industrial sites in an urban area of Beijing, China. Fifty seven typical surface soils were sampled to determine total concentrations of metals, pH and dissolved organic carbon (DOC). One hundred and eight deep soils were submitted to a four-step, sequential extraction to assess the relative mobility and bioavailability of As in the soil profiles. Total concentrations of As in surface soils ranged from 5.7 to 2.3 x 10(1) mg kg(-1), dw with greater concentrations inside the perimeter of the chemical plant which had greater concentrations than did other plants. 75.4% of surface soil samples in the industrial area contained concentrations of As that were greater than was considered to be the background concentration of 7.8 mg kg(-1), dw for the region. The mean concentration (9.9 mg kg(-1), dw) in the industrial soils was greater than that soils from other type of land use. Concentrations of As were significantly and negatively correlated with soil pH and DOC in industrial soils. Although mean concentration of total As in the soils from all sites were less at greater depths, the entire range from 0 to 180 cm (especially 0-80 cm) contained concentrations of As that were greater than background. Sequential extractions of soil indicated that only some surface soils had relatively great amount of extractable fraction of As. Most soils had relatively great amount of residual As. This result suggests that most arsenic in Beijing industrial soils should be immobile and of limited bioavailability.     

Microbial cellulose decomposition in soils from a rifle range contaminated with heavy metals

The objective of this study was to assess the effects of heavy metals on microbial decomposition of cellulose in heavy metal-contaminated soils using a cotton strip assay. The assay is a measure of the potential of soil microorganisms to decompose the plant polymer, cellulose. Cellulolytic activity in soil was assessed by determining the reduction in tensile strength of the buried cotton strips over a 25- and 45-day period. Soils were obtained from a rifle range that contain high levels of lead, copper and zinc. The site has been used for approximately 50 years, resulting in metal levels of up to 30,000 mg/kg of lead, 4000 mg/kg of copper and 600 mg/kg of zinc in the most contaminated soils. All the metal-contaminated soils had lower degradation rates than the uncontaminated soils tested. Among the contaminated soils, however, the heavy metal concentration was not the major factor in determining the loss in tensile strength of the cotton strips, where cellulose decomposition was governed by other soil physicochemical properties. Soil with a higher cation exchange capacity, readily oxidisable material and volatile solids content had the greatest loss in tensile strength of cotton strips. Microbial adaptation to the presence of high concentrations of soil heavy metals and reduced bioavailability of metals is the likely explanation for this phenomenon.     

Bioaugmentation with a Bacillus sp. to reduce the phytoavailable Cd of an agricultural soil: comparison of free and immobilized microbial inocula

In order to reduce the cadmium potentially available for plants, soil bioaugmentation was performed by using a Bacillus sp. In a pot experimentation, sterilized and non-sterilized soils were inoculated using free or immobilized cells entrapped in alginate beads. This test was carried out with different inoculum sizes (2 x 10(10) and 2 x 10(11)CFU kg(-1) dw of soil) and alginate bead compositions (10 and 15 g of both alginate and CaCl(2) l(-1)). Then, the soil pots were incubated at 20 degrees C and the soil humidity was kept at a level of 20%. After 3 weeks of a batch incubation, the potentially phytoavailable Cd was reduced up to a factor of 14. The bioaugmentation resulted in the soil colonization by Bacillus sp. thanks to an increase of the cell concentration up to 1.8 log units. However, in comparison to the cells being inoculated in a free mode, the immobilization of the cells did not significantly improve the survival of the cells in the soil. Although the resulting effect not being highly pronounced, the potentially phytoavailable Cd correlated with the cell concentration in a surprisingly positive way. What is more, the Bacillus concentrations in the soil were positively correlated with the inoculum, too.     

The transportation,time-dependent distribution of heavy metals in paddy crops

Sixteen experimenmtal plots (5 m x 6 m = 30 m2) were designed with four different levels of heavy metals (HMs) concentration in soil. The concentrations of heavy metals in soils, and paddy plant during the different periods of growth were investigated. A relationship between the total HM content in plants and the HM level in soil was found for a wide range of concentrations. The exchangeable fraction of HMs extracted with 1 M MgCl2 solution according to Tessier's method increased correlation with the dosage of supplemented HMs, then decreased as time went on. The time-related variation of exchangeable HMs in soil demonstrated that the amount of effective HMs taken up by paddy differed at various growth phases. The amount of HMs accumulated in different parts of paddy followed the order of root > stem > grain, leaf. The transportation potential of the HMs in paddy in present study followed the order of Zn, Cr > Cd, Cu > Pb. The HM content in root, stem and leaf of paddy plant (dry weight) was low at time of seedling. The concentration in the root increased sharply at time of tillering, decreased thereafter. The concentrations in stem and leaf reached the highest at time of tillering, then decreased, while rose slightly at following time.     

Response of microbial activities in two contrasting soils to 4-nonylphenol treated with biosolids

In the application of biosolids on agricultural lands, 4-nonylphenol (4-NP) in soils is an important environmental concern because of its associated estrogenic risk to animals and human beings. Incubation experiments that involved the mixing of two contrasting soils (A: calcareous sandy soil; B: acidic clayey soil) and biosolids in 4-NP were performed to examine the effect of 4-NP on the rate of production of CO2, the mineralization of N and the microbial biomass, by considering the biodegradation of 4-NP for the evaluation of soil health. The experimental results indicated that the half-life (t1/2) of 4-NP increased with the supplementary concentration of 4-NP (80, 160 and 240 mg kg(-1)) in the two soils, and the t1/2 values in the soil A are always lower than that in soil B. The 4-NP supplement in the biosolids reverses C mineralization in soil B more than it does in soil A, but it reverses N mineralization in soil A more than in soil B. The aeration status and microbial population of the biosolids treated soils are key factors in determining the time course of 4-NP degradation associated with the microbial activities. The 4-NP was biodegraded mainly by bacteria, and the effect on C and N mineralization of 4-NP input is determined by a balance of the reductions in microbial biomass C (MBC) and N (MBN). After destruction in microbial cell membrane and protein structures by the 4-NP, C and N mineralization, MBC and MBN were subsequently followed by a final decline phase for the later period of incubation.     

Evaluating three trace metal contaminated sites: a field and laboratory investigation

Selecting guidelines to evaluate elevated metals in urban brownfields is hindered by the lack of information for these sites on ecosystem structure and function. A study was performed to compare three trace metal-contaminated sites in the metropolitan Montreal area. The goal was to obtain an idea of the organisms that may be present on urban brownfields and to measure if elevated metals alter the presence and activity of the indigenous biota. Field and laboratory studies were conducted using simple methodologies to determine the extent to which microbial activity affected by trace metal content, to assess diversity of plant and soil invertebrate communities and to measure phytoaccumulation of trace metals. It was found that microbial activity, as measured by substrate-induced respiration (SIR) and nitrification, was not affected by the levels of soil Cd, Cu, Ni, Pb and Zn recorded on the sites. Seven of the 12 invertebrate groups collected were sampled on soils with similar Cd, Cu, Ni, Pb and Zn concentrations. Diversity of plant species increased as a function of the length of time the sites had been inactive. Levels of metals in plant tissue were influenced by soil characteristics and not by total soil Cd, Cu, Ni, Pb and Zn.