Prediction of trace element mobility in contaminated soils by sequential extraction

The modified three-step sequential extraction procedure proposed by the Community Bureau of Reference (or Bureau Communautaire de Reference, BCR) was used to predict trace element mobility in soils affected by an accidental spill comprising arsenopyrite- and heavy metal-enriched sludge particles and acid waste waters. The procedure was used to obtain the distribution of both the major (Al, Ca, Fe, Mg, and Mn) and trace elements (As, Bi, Cd, Cu, Pb, Tl, and Zn) in 13 soils of contrasting properties with various levels of contamination and in the sludge itself. The distributions of the major elements enabled us to confirm the main soil fractions solubilized in each of the three steps, and, in turn, to detect the presence of pyritic sludge particles by the high Fe extractability obtained in the third step. Cadmium was identified as being the most mobile of the elements, having the highest extractability in the first step, followed by Zn and Cu, Lead, Tl, Bi, and As were shown to be poorly mobile or nonmobile. In the case of some of the trace elements, the residual fractions decreased at higher levels of contamination, which was attributed to the anthropogenic contributions to the polluted samples. Comparison with soil-plant transfer factors, calculated in plants growing in the affected area, indicated that a relative sequence of trace element mobility was well predicted from data of the first step.     

Trace element removal from coal ash leachate by a 10-year-old constructed wetland

This study investigated the ability of a 10-yr-old constructed wetland to treat metal-contaminated leachate emanating from a coal ash pile at the Widows Creek electric utility, Alabama (USA). The two vegetated cells, which were dominated by cattail (Typha latifolia L.) and soft rush (Juncus effusus L.), were very effective at removing Fe and Cd from the wastewater, but less efficient for Zn, S, B, and Mn. The concentrations were decreased by up to 99% for Fe, 91% for Cd, 63% for Zn, 61% for S, 58% for Mn, and 50% for B. Higher pH levels (>6) in standing water substantially improved the removing efficiency of the wetland for Mn only. The belowground tissues of both cattail and soft rush had high concentrations of all elements; only for Mn, however, did the concentration in the shoots exceed those in the belowground tissues. The concentrations of trace elements in fallen litter were higher than in the living shoots, but lower than in the belowground tissues. The trace element accumulation in the plants accounted for less than 2.5% of the annual loading of each trace element into the wetland. The sediments were the primary sinks for the elements removed from the wastewater. Except for Mn, the concentrations of trace elements in the upper layer (0-5 cm) of the sediment profile tended to be higher than the lower layers (5-10 and 10-15 cm). We conclude that constructed wetlands are still able to efficiently remove metals in the long term (i.e.,>10 yr after construction).     

Baseline concentrations and spatial distribution of trace metals in surface soils of Guangdong province, China

A total of 260 surface soil samples were collected to investigate the spatial distribution of trace metals in Guangdong province, one of the fast developing regions in China. The results show that the upper baseline concentrations of Cu, Pb, Zn, Cd, Ni, Cr, and Hg were 28.7, 57.6, 77.8, 0.13, 23.5, 87.0, and 0.15 mg kg(-1), respectively. Regional parent materials and pedogenesis are the primary factors influencing the concentrations of trace metals, and various anthropogenic activities are the second most important factors. The spatial distribution of trace metals is correlated to the geological characters with high concentrations of trace metals always located in regional fault areas, basins, and the Pearl River Delta alluvial plain and to the low concentrations associated with the other areas in Guangdong province.     

Natural attenuation of residual heavy metal contamination in soils affected by the Aznalcóllar mine spill, SW Spain

Non-amended soils affected by pyritic sludge residues were monitored for 7 years to assess the long-term natural attenuation ability of these soils. The decrease in both the total concentration of elements (particularly As) and (NH(4))(2)SO(4)-extractable fractions of Mn, and Zn, below the maximum permissible levels indicate a successful natural ability to attenuate soil pollution. Soil acidification by pyrite oxidation and rainfall-enhanced leaching were the largest contributors to the reduction of metals of high (Mn, Cu, Zn and Cd) and low (Fe, Al, and As) availability. Periodic use of correlation and spatial distribution analysis was useful in monitoring elemental dispersion and soil property/element relationships.     

四川东部沱江乡茎瘤芥产地的地球化学特征

通过对四川省东部沱江乡茎瘤芥产区土壤的地球化学特征研究和茎瘤芥产区的土壤测试分析，并将其与全国土壤背景值比较，摸清了茎瘤芥产区土壤的元素本底特征。沱江乡茎瘤芥产区土壤Zn、Fe、Mn、Mg、K、B、P元素含量高于全国土壤平均含量，有益元素Mo、Ca、Si、Se均比全国平均值低，重金属Cr、Hg、Cd、Pb含量比全国平均值高，As元素含量则低于全国平均值水平，产区土壤中存在的Cd元素超出国家环境质量一级标准，但符合二级土壤质量标准，其他元素符合绿色蔬菜产地环境标准。     

On-farm assessment of biosolids effects on soil and crop tissue quality

Agronomic use of biosolids as a fertilizer material remains controversial in part due to public concerns regarding the potential pollution of soils, crop tissue, and ground water by excess nutrients and trace elements in biosolids. This study was designed to assess the effects of long-term commercial-scale application of biosolids on soils and crop tissue sampled from 18 production farms throughout Pennsylvania. Biosolids application rates ranged from 5 to 159 Mg ha(-1) on a dry weight basis. Soil cores and crop tissue samples from corn (Zea mays L.), soybean (Glycine spp.), alfalfa (Medicago sativa L.), orchardgrass (Dactylis spp.) hay, and/or sorghum [Sorghum bicolor (L.) Moench] were collected for three years from georeferenced locations at each farm. Samples were tested for nutrients, trace elements, and other variables. Biosolids-treated fields had more post-growing season soil NO3 and Ca and less soil K than control fields and there was some evidence that soil P concentrations were higher in treated fields. The soil concentrations of Cu, Cr, Hg, Mo, Mn, Pb, and Zn were higher in biosolids-treated fields than in control fields; however, differences were < or = 0.06 of the USEPA Part 503 cumulative pollutant loading rates (CPLRs). There were no differences in the concentrations of measured nutrients or trace elements in the crop tissue grown on treated or control fields at any time during the study. Commercial-scale biosolids application resulted in soil trace element increases that were in line with expected increases based on estimated trace element loading. Excess NO3 and apparent P buildup indicates a need to reassess biosolids nutrient management practices.     

Distribution of heavy metals in sediments of Igbede, Ojo and Ojora rivers of Lagos, Nigeria

The distribution of some heavy metals, namely Cd, Pb, Zn, Fe, Cu, Cr and Mn in epipellic sediments of Igbede, Ojo and Ojora rivers of Lagos was studied weekly in the early summer (November) of 2003. The levels of selected trace metals were determined using Atomic Absorption Spectrophotometer (UNICAM 969 AAS SOLAR). Trends in heavy metal burdens in the sediments revealed weekly variations in all the rivers assessed. Statistical analyses also showed different mean levels of trace metals in the aquatic environments, the distribution of which followed the sequence Fe > Zn > Mn > Pb > Cu > Cr > Cd, Fe > Zn > Cu > Mn > Pb > Cr > Cd and Fe > Zn > Mn > Cu > Cr > Pb > Cd in Igbede, Ojo and Ojora rivers respectively. Fe recorded the highest concentration levels (1,582.95 ± 96.57 μ g/g–1,910.34 ± 723.19 μ g/g) in all the sediments investigated while the Cd levels (0.06 ± 0.10 μ g/g–0.47 ± 0.36 μ g/g) were the lowest. Expectedly, trace metal concentrations in fine grain muddy sediments of the Igbede and Ojo coastline were much higher than those of Ojora which consist of coarse and sandy deposits covering the near shore area. Generally, the results obtained fell within tolerable limits stipulated by World Health Organization (WHO).     

An inventory of trace element inputs to agricultural soils in China

It is important to understand the status and extent of soil contamination with trace elements to make sustainable management strategies for agricultural soils. The inputs of trace elements to agricultural soils via atmospheric deposition, livestock manures, fertilizers and agrochemicals, sewage irrigation and sewage sludge in China were analyzed and an annual inventory of trace element inputs was developed. The results showed that atmospheric deposition was responsible for 43–85% of the total As, Cr, Hg, Ni and Pb inputs, while livestock manures accounted for approximately 55%, 69% and 51% of the total Cd, Cu and Zn inputs, respectively. Among the elements concerned, Cd was a top priority in agricultural soils in China, with an average input rate of 0.004 mg/kg/yr in the plough layer (0–20 cm). Due to the spatial and temporal heterogeneity of the sources, the inventory as well as the environmental risks of trace elements in soils varies on a regional scale. For example, sewage sludge and fertilizers (mainly organic and phosphate-based inorganic fertilizers) can also be the predominant sources of trace elements where these materials were excessively applied. This work provides baseline information to develop policies to control and reduce toxic element inputs to and accumulation in agricultural soils.     

Latent effect of soil organic matter oxidation on mercury cycling within a southern boreal ecosystem

The focus of this study is to investigate processes causing the observed spatial variation of total mercury (THg) in the soil O horizon of watersheds within the Superior National Forest (Minnesota) and to determine if results have implications toward understanding long-term changes in THg concentrations for resident fish. Principal component analysis was used to evaluate the spatial relationships of 42 chemical elements in three soil horizons over 10 watersheds. Results indicate that soil organic carbon is the primary factor controlling the spatial variation of certain metals (Hg, Tl, Pb, Bi, Cd, Sn, Sb, Cu, and As) in the O and A soil horizons. In the B/E horizon, organic carbon appeared to play a minor role in metal spatial variation. These characteristics are consistent with the concentration of soil organic matter and carbon decreasing from the O to the B/E horizons. We also investigated the relationship between percent change in upland soil organic content and fish THg concentrations across all watersheds. Statistical regression analysis indicates that a 50% reduction in age-one and age-two fish THg concentration could result from an average 10% decrease in upland soil organic content. Disturbances that decrease the content of THg and organic matter in the O and A horizons (e.g., fire) may cause a short-term increase in atmospherically deposited mercury but, over the long term, may lead to decreased fish THg concentrations in affected watersheds.     

Atmospheric supply of trace elements studied by peat samples from ombrotrophic bogs

Concentrations of Fe and 12 trace elements in peat from ombrotrophic bogs were used to estimate the atmospheric deposition of these elements on a temporal and spatial scale. Peat samples were collected at 21 different sites in Norway encompassing large geographical differences in marine influence and air pollution. The study demonstrates that surface peat is an excellent medium to study geographical differences in heavy metal deposition, provided that effects of the surface plant cover are properly considered. Long-range atmospheric transport of pollutants is the main source for As, Cd, Pb, Sb, and Zn, and to a lesser extent for Cu and Se. Biogenic emissions from the ocean appear to be the main source of Se to the peat. The metals Co, Cr, Fe, and Ni are mainly associated with wind-blown local soil dust. Surface enrichment of Mn, and in part Zn, is mainly caused by nutrient circulation between the surface peat and vascular plants growing on it. Deposition of marine salts appears to be the main reason for lower Mn concentrations in the peat near the coast.     

Arsenic, cadmium, and lead in California cropland soils: role of phosphate and micronutrient fertilizers

Phosphate and micronutrient fertilizers contain potentially harmful trace elements, such as arsenic (As), cadmium (Cd), and lead (Pb). We investigated if application of these fertilizer increases the As, Cd, and Pb concentrations of the receiving soils. More than 1000 soil samples were collected in seven major vegetable production regions across California. Benchmark soils (no or low fertilizer input) sampled in 1967 and re-sampled in 2001 served as a baseline. Soils were analyzed for total concentrations of As, Cd, Pb, P, and Zn. The P and Zn concentrations of the soils were indicators of P fertilizer and micronutrient inputs, respectively. Results showed that the concentrations of these elements in the vegetable production fields in some production areas of California had been shifted upward. Principal component analysis and cluster analysis showed that the seven production areas could be sorted into three categories: (i) enrichment of As, Cd, and Pb, which was associated with the enrichment of P and Zn in one of the seven areas surveyed; (ii) enrichment of As, which was associated with enrichment of Zn in two of the seven areas surveyed; and (iii) no remarkable correlation between enrichment of As, Cd, and Pb and enrichment of P and Zn in the other four areas surveyed.     

Total Contents and Sequential Extraction of Heavy Metals in Soils Irrigated with Wastewater,Akaki, Ethiopia

The Akaki River, laden with untreated wastes from domestic, industrial, and commercial sources, serves as a source of water for irrigating vegetable farms. The purpose of this study is to identify the impact of waste-water irrigation on the level of heavy metals and to predict their potential mobility and bioavailability. Zn and V had the highest, whereas Hg the lowest, concentrations observed in the soils. The average contents of As, Co, Cr, Cu, Ni, Zn, V, and Hg of both soils; and Pb and Se from Fluvisol surpassed the mean + 2 SD of the corresponding levels reported for their uncontaminated counterparts. Apparently, irrigation with waste water for the last few decades has contributed to the observed higher concentrations of the above elements in the study soils (Vertisol and Fluvisol) when compared to uncontaminated Vertisol and Fluvisol. On the other hand, Vertisol accommodated comparatively higher average levels of Cr, Cu, Ni, Zn, etc V, and Cd, whereas high contents of Pb and Se were observed in Fluvisol. Alternatively, comparable levels of Co and Hg were found in either soil. Except for Ni, Cr, and Cd in contaminated Vertisol, heavy metals in the soils were not significantly affected by the depth (0–20 and 30–50 cm). When the same element from the two soils was compared, the levels of Cr, Cu, Ni, Pb, Se, Zn, V, Cd at 0–20 cm; and Cr, Ni, Cu, Cd, and Zn at 30–50 cm were significantly different. Organic carbon (in both soils), CEC (Fluvisol), and clay (Vertisol) exhibited significant positive correspondences with the total heavy metal levels. Conversely, Se and Hg contents revealed perceptible associations with carbonate and pH. The exchangeable fraction was dominated by Hg and Cd, whereas the carbonate fraction was abounded with Cd, Pb, and Co. conversely, V and Pb displayed strong affinity to reducible fraction, where as Cr, Cu, Zn, and Ni dominated the oxidizable fraction. Cr, Hg, Se, and Zn (in both soils) showed preference to the residual fraction. Generally, a considerable proportion of the total levels of many of the heavy metals resided in non residual fractions. The enhanced lability is generally expected to follow the order: Cd > Co > Pb > Cu > Ni > Se > V and Pb > Cd > Co > Cu > Ni > Zn in Vertisol and Fluvisol, respectively. For the similar wastewater application, the soil variables influence the status and the distribution of the associated heavy metals among the different soil fractions in the study soils. Among heavy metals that presented relatively elevated levels and with potential mobility, Co, Cu, Ni (either soil), V (Vertisol), Pb, and Zn (Fluvisol) could pose health threat through their introduction into the food chain in the wastewater irrigated soils.     

Overexpression of ATP sulfurylase in Indian mustard: effects on tolerance and accumulation of twelve metals

Indian mustard [Brassica juncea (L.) Czern.] transgenics overexpressing ATP sulfurylase (APS plants) were shown previously to have higher levels of total thiols, S, and Se. The present study explores the effect of ATP sulfurylase overexpression on tolerance and accumulation of other metals, both oxyanions and cations, reasoning that some anions may react directly with ATP sulfurylase, while other ions may be bound by its thiol end products. The APS transgenics were compared with wild-type plants with respect to tolerance and accumulation of As, Cd, Cr, Cu, Hg, Mn, Mo, Ni, Pb, V, W, and Zn, supplied individually in agar medium (seedlings) or in hydroponics (mature plants). At the seedling stage, APS transgenics were more tolerant than wild type to As(III), As(V), Cd, Cu, Hg, and Zn, but less tolerant to Mo and V. The APS seedlings had up to 2.5-fold higher shoot concentrations of As(III), As(V), Hg, Mo, Pb, and V, and somewhat lower Cr levels. Mature APS plants contained up to 2.5-fold higher shoot concentrations of Cd, Cr, Cu, Mo, V, and W than wild type. They also contained 1.5- to 2-fold higher levels of the essential elements Fe, Mo, and S in most of the treatments. Mature APS plants showed no differences in metal tolerance compared with the wild type. Overexpression of ATP sulfurylase may be a promising approach to create plants with enhanced phytoextraction capacity for mixtures of metals.     

DISTRIBUTION AND GRAIN-SIZE PARTITIONING OF METALS IN BOVFOM SEDIMENTS OF AN EXPERIMENTALLY ACIDIFIED WISCONSIN LAKE1

ABSTRACT: A study of concentrations and distribution of major and trace elements in surficial bottom sediments of Little Rock Lake in northern Wisconsin included examination of spatial variation and grain-size effects. No significant differences with respect to metal distribution in sediments were observed between the two basins of the lake, despite the experimental acidification of one of the basins from pH 6.1 to 4.6. The concentrations of most elements in the lake sediments were generally similar to soil concentrations in the area and were well below sediment quality criteria. Two exceptions were lead and zinc, whose concentrations in July 1990 exceeded the criteria of 50 μg/g and 100 μg/g, respectively, in both littoral and pelagic sediments. Concentrations of some elements, particularly Cu, Pb, and Zn, increased along transects from nearshore to midlake, following a similar gradient of sedimentary organic carbon. In contrast, Mn, Fe, and alkali/alkaline-earth elements were at maximum concentrations in nearshore sediments. These elements are less likely to partition to organic particles, and their distribution is more dependent on mineralogical composition, grain size, and other factors. Element concentrations varied among different sediment grain-size fractions, although a simple inverse relation to grain size was not observed. Fe, Mn, Pb, and Zn were more concentrated in a grain-size range 20–60 tm than in either the very fine or the coarse fractions, possibly because of the aggregation of smaller particles cemented together by organic and Fe/Mn hydrous-oxide coatings.     

Metal contamination of surface water,sediment and <Emphasis Type="Italic">Tympanotonus fuscatus</Emphasis> var. <Emphasis Type="Italic">radula</Emphasis> of Iko River and environmental impact due to Utapete gas flare station,Nigeria

Inter-seasonal studies on the trace metal load of surface water, sediment and Tympanotonus fuscatus var. radula of Iko River were conducted between 2003 and 2004. The impact of anthropogenic activities especially industrial effluent, petroleum related wastes, gas flare and episodic oil spills on the ecosystem are remarkable. Trace metals analyzed included cadmium (Cd), chromium (Cr), copper (Cu), iron (Fe), lead (Pb), manganese (Mn), nickel (Ni), vanadium (V) and zinc (Zn). Sediment particle size analysis revealed that they were characteristically psammitic and were predominantly of medium to fine grained sand (>73%), less of silt (<15%) and clay (<10%). These results correlated with low levels of trace elements such as Pb (0.03 ± 0.02 mg kg⁻¹), Cr (0.22 ± 0.12 mg kg⁻¹), Cd (0.05 ± 0.03 mg kg⁻¹), Cu (0.04 ± 0.02 mg kg⁻¹) and Mn (0.23 ± 0.22 mg kg⁻¹) in the sediment samples. This observation is consistent with the scarcity of clayey materials known to be good scavengers for metallic and organic contaminants. Sediments indicated enhanced concentration of Fe, Ni and V, while other metal levels were relatively low. The concentrations of all the metals except Pb in surface water were within the permissible levels, suggesting that the petroleum contaminants had minimal effect on the state of pollution by trace metals in Iko River. Notably, the pollutant concentrations in the sediments were markedly higher than the corresponding concentrations in surface water and T. fuscatus tissues, and decreased with distance from point sources of pollution.     

三峡库区土壤中有效态微量元素含量的区划

本文建立了三峡库区土壤中有效态微量元素含量的区划原则。根据确立的有效态微量元素含量丰缺的指标，运用等值线图法，采用微机处理，最后将库区划分为八个土壤亚区。     

Multivariate statistics to investigate metal contamination in surface soil

The modification of soil composition in the urbanized area of Ankara due to wet-dry deposition and pollution-derived particles from the atmosphere is investigated by analyzing 120 surface soil samples, collected from the urbanized area and its un-urbanized surrounding, for major, minor and trace elements. Concentrations of elements from human activity (e.g. Cd, Pb, Cr, Zn, Cu and Ca) in the urbanized area were higher than their corresponding concentrations in global average soil and soil in un-urbanized areas outside the urbanized area. Metal contents in soil were very high in densely populated districts and around some industrial facilities. The only exception was Pb distribution, which was more dispersed, due to the nature of motor vehicle emissions. Alteration of the Cd, Zn, Cu and Cr content of soil was confined to the inhabited and industrial areas, whereas enrichment factors of these elements were close to unity in the remaining study area. Factor analysis identified two polluted soil factor associations. One factor includes elements, such as Zn and Cd, which had high factor scores in inhabited areas and the other factor (high loading of Pb) represents soil polluted by motor vehicle emissions.     

micro-XANES and micro-XRF investigations of metal binding mechanisms in biosolids

Micro-X-ray fluorescence (micro-XRF) microprobe analysis and micro-X-ray absorption near-edge structure (micro-XANES) spectroscopy were employed to identify Fe and Mn phases and their association with selected metals in two biosolids (limed composted [LC] and Nu-Earth) before and after treatment to remove organic carbon (OC). Spatial correlations derived from elemental mapping of XRF images showed strong correlations between Fe and Cd, Cr, Pb, or Zn (r2= 0.65-0.92) before and after removal of most of the OC. The strong correlation between Fe and Cu that was present in intact samples disappeared after OC removal, suggesting that Cu was associated with OC coatings that may have been present on Fe compounds. Except for Fe and Cr, the spatial correlations of metals with Mn were improved after treatment to remove OC, indicating that the treatment may have altered more than the OC in the system. The Fe micro-XANES spectra of the intact biosolids sample showed that every point had varying mixtures of Fe(II and III) species and no two points were identical. The lack of uniformity in Fe species in the biosolids sample illustrates the complexity of the materials and the difficulty of studying biosolids using conventional analytical tools or chemical extraction techniques. Still, these microscopic observations provide independent information supporting the previous laboratory and field hypothesis that Fe compounds play a major role in retention of environmentally important trace elements in biosolids. This could be due to co-precipitation of the metals with Fe, adsorption of metals by Fe compounds, or a combination of both mechanisms.     

Dissolution of trace element contaminants from two coastal plain soils as affected by pH

Trace element mobility in soils depends on contaminant concentration, chemical speciation, water movement, and soil matrix properties such as mineralogy, pH, and redox potential. Our objective was to characterize trace element dissolution in response to acidification of soil samples from two abandoned incinerators in the North Carolina Coastal Plain. Trace element concentrations in 11 soil samples from both sites ranged from 2 to 46 mg Cu kg(-1), 3 to 105 mg Pb kg(-1), 1 to 102 mg Zn kg(-1), 3 to 11 mg Cr kg(-1), < 0.1 to 10 mg As kg(-1), and < 0.01 to 0.9 mg Cd kg(-1). Acidified CaCl2 solutions were passed through soil columns to bring the effluent solution to approximately pH 4 during a 280-h flow period. Maximum concentrations of dissolved Cu, Pb, and Zn at the lowest pH of an experiment (pH 3.8-4.1) were 0.32 mg Cu L(-1), 0.11 mg Pb L(-1), and 1.3 mg Zn L(-1) for samples from the site with well-drained soils, and 0.25 mg Cu L(-1), 1.2 mg Pb L(-1), and 1.4 mg Zn L(-1) for samples from the site with more poorly drained soils. Dissolved Cu concentration at pH 4 increased linearly with increasing soil Cu concentration, but no such relationship was found for Zn. Dissolved concentrations of other trace elements were below our analytical detection limits. Synchrotron X-ray absorption near edge structure (XANES) spectroscopy showed that Cr and As were in their less mobile Cr(III) and As(V) oxidation states. XANES analysis of Cu and Zn on selected samples indicated an association of Cu(II) with soil organic matter and Zn(II) with Al- and Fe-oxides or franklinite.     

Novel passive co-treatment of acid mine drainage and municipal wastewater

A laboratory-scale, four-stage continuous-flow reactor system was constructed to test the viability of high-strength acid mine drainage (AMD) and municipal wastewater (MWW) passive co-treatment. Synthetic AMD of pH 2.6 and acidity of 1870 mg L(-1) as CaCO3 equivalent containing a mean 46, 0.25, 2.0, 290, 55, 1.2, and 390 mg L(-1) of Al, As, Cd, Fe, Mn, Pb, and Zn, respectively, was added at a 1:2 ratio with raw MWW from the City of Norman, OK, to the system which had a total residence time of 6.6 d. During the 135-d experiment, dissolved Al, As, Cd, Fe, Mn, Pb, and Zn concentrations were consistently decreased by 99.8, 87.8, 97.7, 99.8, 13.9, 87.9, and 73.4%, respectively, pH increased to 6.79, and net acidic influent was converted to net alkaline effluent. At a wasting rate of 0.69% of total influent flow, the system produced sludge with total Al, As, Cd, Cr, Cu, Fe, Pb, and Zn concentrations at least an order of magnitude greater than the influent mix, which presents a metal reclamation opportunity. Results indicate that AMD and MWW passive co-treatment is a viable approach to use wastes as resources to improve water quality with minimal use of fossil fuels and refined materials.