Metals in vineyard soils of the Penedès area (NE Spain) after compost application

The application of organic wastes to improve soil physical characteristics in mechanized vineyards planted after land levelling is becoming a common practice in Mediterranean areas. It may be useful as an additional source of organic matter and nutrients, but these wastes could also have negative effects due to their metal content. The aim of the study was to evaluate the influence of compost application on soil metal contents in mechanized vineyard soils of the Spanish Mediterranean area, where this practice is repeated every three years. The study was carried out in a ten-year-old vineyard where the main soil type is Typic Calcixerept. Composted cattle manure was applied in alternate rows, at a rate of 40 Mgha(-1) dry-weight. Nine sampling points were located along the slopes of two plots: a levelled plot prepared for mechanization with large soil disturbance movements within the plot, and a plot of undisturbed soil. At each location, soil samples were taken in both treated and untreated soils. Total concentrations (digestion with aqua regia) and the extractable DTPA (Diethylene-triaminepentacetic)-CaCl2-TEA (Triethanolamine) fractions of Cu, Zn and Mn were analyzed in each sample. For Cu and Zn, the initial concentration was higher in the undisturbed plot. In both cases, total Cu and total Zn were positively affected by manure input and the concentration in treated soils was significantly higher than in untreated soil. For Mn, the initial concentration was higher in disturbed soils than in undisturbed ones, and although in both scenarios the concentrations increased with manure, no significant differences were found between treated and untreated soils. The extractable fraction also increased in treated versus untreated soils, although for Cu and Mn the extractable/total metal ratio was similar in treated and untreated soils. After one compost application, total metal contents increased significantly, particularly for Zn. Most of those metals are accumulated in the soil, due to the soil characteristics.     

河南农田土壤重金属污染状况及其评价

在河南境内取自农田土壤102例表层样品，分析了其中的Cr、Zn、Cu、Pb、Ni、As等8种重金属元素的含量。结果表明：河南农田土壤中除Cr偶有超出我国《土壤环境质量标准》（GB15618—1995）二级标准的土样外，其他项目均不超标，重金属污染由高到低排序为Cr〉Zn〉Ni〉Cd〉Hg〉Cu〉Pb〉As。重金属元素在河南各土壤利用类型中分布规律不明显，按4种主要土壤利用类型考查来看，重金属污染程度大小排序为：果园地〉水田〉菜地〉其他粮田；河南农田土壤综合污染指数总平均为0．981，土壤总体为尚清洁，重金属污染处于警戒水平；河南农田土壤中Cr含量较高的土壤主要是粗骨土与石质土，其天然本底值较高。     

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.     

Characteristic levels of heavy metals in soil profiles of automobile mechanic waste dumps in Nigeria

The characteristic levels of heavy metals (Cd, Cr, Cu, Pb, Ni and Zn) of soil profiles of automobile mechanic waste dumps were studied. The concentration of heavy metals decreased with the depth of the profile and lateral distance from the dumpsites. The levels found in this study exceeded background concentrations and limits for agricultural and residential purposes. The distribution pattern of heavy metals in the soil profiles were in the following order Pb > Zn > Cu > Cd > Ni > Cr. The mechanic waste dumps represent potential sources of heavy metal pollution to environment. The elevated levels of heavy metals in these soil profiles constitute a serious threat to both surface and groundwater.     

河流底泥重金属污染及潜在生态风险评价——以湘江株洲段为例

通过对湘江株洲段6个监测断面左右两岸共32个底泥样品重金属Pb,Zn,Cd,As,Hg和Cr质量比进行分析研究,并进行潜在生态风险评价。结果表明：霞湾断面是重金属富集最严重的断面;Cd,Hg和As的含量均超过GB15618—1995三级标准和长沙-湘潭-株洲3市土壤背景值;重金属含量大部分分布特征为右岸高于左岸;从重金属污染的潜在生态风险看,湘江株洲段各监测断面潜在生态风险都很高;各重金属元素对生态风险影响程度从大到小的顺序为：Hg〉Cd〉As〉Pb〉Zn〉Cr。     

Changes in the rhizosphere of metal-accumulating plants evidenced by chemical extractants

The plants Salix viminalis L. (common osier) and Thlaspi caerulescens J. Presl & C. Presl have been studied often because of their high potential to extract heavy metals from soils. The soil properties favoring this phytoextraction are not yet fully known. In this study we compared three frequently used single-extracting agents (NaNO3, diethylenetriaminepentaacetic acid [DTPA], and ethylenediaminetetra-acetic acid [EDTA]) with a sequential extraction procedure to describe changes in the different Cd, Cu, and Zn pools in the rhizosphere of S. viminalis and T. caerulescens grown on calcareous and acidic Swiss soils in a pot experiment. The sequential extraction was used to assess the chemical affinities of these heavy metals (HM) in the soil whereas the single extractants were used for estimating the bioavailable HM pools in the soils. Cadmium depletion in several pools was most apparent in the acidic soil, with a significant decrease observed in the NaNO3-, DTPA-, and EDTA-extractable fractions following T. caerulescens growth compared with control pots. The sequential extraction showed that most Cd extracted by the plant from the acidic soil originated from the organic pool, which implies that heavy metals bound to organic matter may constitute a significant part of the bioavailable Cd pool in soils. In the calcareous soil only a small amount of Cd was taken up by T. caerulescens, and this came mainly from the carbonate-bound fraction. This study shows that T. caerulescens, and to a lesser extent S. viminalis, can alter the heavy metal distribution in different soil pools within 90 d.     

宝山区农用土壤中重金属的监测与评价

在研究的8种重金属元素中,Cd、Cr、Cu、Pb、Zn、Ni的平均值都超过上海市土壤背景值,但均低于国家土壤环境二级标准。与上海优质农产地环境标准相比较,重金属含量平均值超过标准的有Cr、Pb、Zn,但研究区土壤中8种重金属含量的平均值均低于绿色食品产地环境技术条件和无公害食品产地环境技术条件。宝山区7个城镇农业土壤按多因子潜在生态危害指数评价,庙行镇的生态风险指数最高,月浦镇的生态风险指数最低。从宝山区农田土壤重金属含量的整体情况来看:多因子潜在生态评价值为119.08,宝山区农田土壤达到轻微生态危害。     

杭州城区河道底泥重金属污染及潜在生态风险评价

对杭州城区34条河道45个点位河道底泥进行采样,分析了pH及汞、砷、铅、铬、镉、铜、锌、镍等重金属含量,并进行污染及潜在生态风险评价。结果表明,监测点位的底泥为中性偏碱性,重金属含量分布不均,且范围波动很大,部分河道底泥重金属中汞、铅、镉、铬、锌、镍等有不同程度的超标,少数河道镉、铬、锌污染严重;按《农用污泥中污染物控...     

柴窝堡湖表层底泥重金属污染评价

研究了乌鲁木齐市柴窝堡湖表层底泥的重金属含量,并采用Hakanson潜在生态危害指数法对底泥中的重金属潜在生态风险进行评价。结果表明:底泥中Cu、Zn、Pb、Cd含量均超出乌鲁木齐市土壤背景值。除湖心区外,Cd在5个监测区域中的潜在生态危害均为中等;其它重金属在5个采样点的潜在生态危害均为轻微。各重金属间的相关性分析表明,Zn与Cu,Pb与Cd、Cu呈显著正相关,说明这4种元素污染源可能相同。柴窝堡湖表层底泥受到Cu、Zn、Pb、Cd污染,需采取相应措施防止重金属由底泥进入水相。     

湘中某工业区农田重金属污染的初步研究

通过2年的定点调查,研究了湘中某工业区附近农田土壤、糙米中重金属含量状况;并对重金属在水稻植株中的含量分布,以及影响糙米中重金属含量的土壤因素进行了探讨。     

Fractionation and mobility of copper, lead, and zinc in soil profiles in the vicinity of a copper smelter

Four soil profiles located near a copper smelter in Poland were investigated for the distribution and chemical fractions of Cu, Pb, and Zn and their mobility in relation to soil properties. Contamination with heavy metals was primarily restricted to surface horizons and the extent of contamination was 7- to 115-fold for Cu, 30-fold for Pb, and 6-fold for Zn as compared with subsurface horizons. In the less-contaminated fine-textured soil, the metals were distributed in the order: residual > Fe-Mn oxides occluded > organically complexed > exchangeable and specifically adsorbed, while the order for sandy soils was: residual > organically complexed > Fe-Mn oxides occluded > exchangeable and specifically adsorbed. The contaminated surface horizons of these profiles showed no consistent pattern of metal distribution. However, the common features of highly contaminated soils were very low percentage of residual fraction and the dominance of the NH4OAc extractable fraction. The sum of mobile metal fractions was generally < 10% in subsurface horizons, while in the contaminated surface horizons these fractions made up 50% of the total metal contents. Soil properties contributed more to the relative distribution of the metal fractions in the studied profiles than did the distance and direction to the source of pollution. The amounts of metal extracted by 0.01 M CaCl2 accounted for only a small part of the same metals extracted by NH4OAc. The mobility indexes of metals correlated positively and significantly with the total content of metals and negatively with the clay content.     

Heavy metal distribution and chemical speciation in tailings and soils around a Pb-Zn mine in Spain

Soil pollution by lead, zinc, cadmium and copper was characterized in the mine tailings and surrounding soils (arable and pasture lands) of an old Spanish Pb-Zn mine. Sixty soil samples were analyzed, determining the total metal concentration by acid digestion and the chemical fractionation of Pb and Zn by the modified BCR sequential extraction method. Samples belonging to mine waste areas showed the highest values, with mean concentrations of 28,453.50 mg kg(-1) for Pb, 7000.44 mg kg(-1) for Zn, 20.57 mg kg(-1) for Cd and 308.48 mg kg(-1) for Cu. High concentrations of Pb, Zn and Cd were found in many of the samples taken from surrounding arable and pasture lands, indicating a certain extent of spreading of heavy metal pollution. Acidic drainage and wind transport of dust were proposed as the main effects causing the dispersion of pollution. Sequential extraction showed that most of the Pb was associated with non-residual fractions, mainly in reducible form, in all the collected samples. Zn appeared mainly associated with the acid-extractable form in mine tailing samples, while the residual form was the predominant one in samples belonging to surrounding areas. Comparison of our results with several criteria reported in the literature for risk assessment in soils polluted by heavy metals showed the need to treat the mine tailings dumped in the mine area.     

Uncertainty and sensitivity analysis of spatial predictions of heavy metals in wheat

Heavy metals seriously threaten the health of human beings when they enter the food chain. Therefore, policymakers require precise predictions of heavy metal concentrations in agricultural crops. In this paper we quantify the uncertainty of regression predictions of Cd and Pb in wheat (Triticum aestivum L.) and the contributions to the uncertainties in these predictions associated with inputs to the regression model. For each node of the 500- x 500-m grid covering the arable soils in The Netherlands, a latin hypercube sample size of 1000 is constructed from the uncertainty distributions of the explanatory variables (pH, soil organic matter [SOM], and heavy metal concentration in soil), the regression coefficients, and the random term of the regression model. This sample is used as input for the regression model to obtain 1000 values from the uncertainty distributions of the log(Cd) and log(Pb) concentration in wheat. There were no nodes where the recent EU quality standards for Cd and Pb (0.2 mg kg(-1) fresh wt.) in wheat were almost certain to be exceeded. For most nodes with clay soils, the quality standard for Cd in wheat almost certainly will not be exceeded; for Pb this is much less certain. The uncertainty in the Cd concentration in soil contributes most to the uncertainty in the predicted Cd concentrations in wheat (36% on the average), followed by the random term of the regression model (23%). For Pb the contribution of the random term is by far the largest (52%).     

Prediction of zinc, cadmium, lead, and copper availability to wheat in contaminated soils using chemical speciation, diffusive gradients in thin films, extraction, and isotopic dilution techniques

To predict the availability of metals to plants, it is important to understand both solution- and solid-phase processes in the soil, including the kinetics of metal release from its binding agent (ligand and/or particle). The present study examined the speciation and availability of Zn, Cd, Pb, and Cu in a range of well-equilibrated metal-contaminated soils from diverse sources using several techniques as a basis for predicting metal uptake by plants. Wheat (Triticum aestivum L.) was grown in 13 metal-contaminated soils and metal tissue concentrations (Zn, Cd, Pb, and Cu) in plant shoots were compared with total soil metal concentrations, total soluble metal, and free metal activities (pM2+) in soil pore waters, 0.01 M CaCl2-extractable metal concentrations, E values measured by isotope dilution, and effective metal concentrations, C(E), measured by diffusive gradients in thin films (DGT). In the DGT technique, ions are dynamically removed by their diffusion through a gel to a binding resin, while E values represent the isotopically exchangeable (labile) metal pools. Free metal activities (Zn2+, Cd2+, and Pb2+) in soil pore waters were determined using a Donnan dialysis technique. Plant Zn and Cd concentrations were highly related to C(E), while relationships for Zn and Cd with respect to the other measures of metals in the soils were generally lower, except for CaCl2-extractable Cd. These results suggest that the kinetically labile solid-phase pool of metal, which is included in the DGT measurement, played an important role in Zn and Cd uptake by wheat along with the labile metal in soil solution. Plant Pb concentrations were highly related to both soil pore water concentrations and C(E), indicating that supply from the solid phase may not be so important for Pb. Predictions of Cu uptake by wheat from these soils by the various measures of Cu were generally poor, except surprisingly for total Cu.     

Hydrophobicity of soil colloids and heavy metal mobilization: effects of drying

Drying of soil may increase the hydrophobicity of soil and affect the mobilization of colloids after re-wetting. Results of previous research suggest that colloid hydrophobicity is an important parameter in controlling the retention of colloids and colloid-associated substances in soils. We tested the hypothesis that air-drying of soil samples increases the hydrophobicity of water-dispersible colloids and whether air-drying affects the mobilization of colloid-associated heavy metals. We performed batch experiments with field-moist and air-dried (25 degrees C) soils from a former sewage farm (sandy loam), a municipal park (loamy sand), and a shooting range site (loamy sand with 25% C(org)). The filtered suspensions (<1.2 microm) were analyzed for concentrations of dissolved and colloidal organic C and heavy metals (Cu, Cd, Pb, Zn), average colloid size, zeta potential, and turbidity. The hydrophobicity of colloids was determined by their partitioning between a hydrophobic solid and a hydrophilic aqueous phase. Drying increased hydrophobicity of the solid phase but did not affect the hydrophobicity of the dispersed colloids. Drying decreased the amount of mobilized mineral and (organo-)mineral colloids in the sewage farm soils but increased the mobilization of organic colloids in the C-rich shooting range soil. Dried samples released less colloid-bound Cd and Zn than field-moist samples. Drying-induced mobilization of dissolved organic C caused a redistribution of Cu from the colloidal to the dissolved phase. We conclude that drying-induced colloid mobilization is not caused by a change in the physicochemical properties of the colloids. Therefore, it is likely that the mobilization of colloids in the field is caused by increasing shear forces or the disintegration of aggregates.     

Determination and Evaluation of Cadmium, Copper, Nickel, and Zinc in Agricultural Soils of Western Macedonia, Greece

The objective of this study was to determine the levels of major phytotoxic metals―including cadmium (Cd), copper (Cu), nickel (Ni), and zinc (Zn)―in agricultural soils of Western Macedonia, Greece. We also wanted to determine the possible relationships among elements and between soil properties and elemental concentrations. Surface soil samples, n = 570, were collected and analyzed. The results of the elemental analysis showed that the mean metal concentrations were consistent with reported typical concentrations found in Greek agricultural soils in the cases of Zn and Cu. Cd exhibited lower and Ni higher mean concentrations than the typical levels reported in the literature. Metal concentrations in the majority of the examined samples (>69%) were found to be higher than the respective critical plant-deficiency levels. However, only 0.4% and 0.2% of the analyzed soil samples, respectively, exhibited Cd and Ni concentrations higher than the levels that cause plant toxicity, as referenced by other investigators. These results suggest that the soils studied can be considered as unpolluted with respect to the examined food-chain metal contaminants. However, the levels of the metal concentrations in some of the soil samples, and the low correlation of the metals with soil properties, suggest an anthropogenic rather that lithogenic origin.     

Retention of heavy metals in a Typic Kandiudult amended with different manure-based biochars

Although nutrient-rich manure biochars are expected to be an effective heavy metal stabilizer in agricultural and contaminated soils, systematic studies are lacking to predict the influence of manure variety and pyrolysis temperature on metal-binding potentials. In this study, biochars produced from five manure varieties (dairy, paved feedlot, swine solids, poultry litter, and turkey litter) at two pyrolytic temperatures (350 and 700°C) were examined for the stabilization of Pb, Cu, Ni, and Cd in a weathered, acidic Norfolk loamy sand (fine-loamy, kaolinitic, thermic, Typic Kandiudult). Equilibrium concentrations in the aqueous phase were determined for heavy metals (Cu, Ni, Cd, and Pb) and additional selected elements (Na, P, S, Ca, Mg, Al, and K); these were analyzed by positive matrix factorization to quantitatively determine the factors responsible for the biochar's ability to bind the selected heavy metals in soil. Concurrently with the greatest increase in pH and highest equilibrium Na, S, and K concentrations, poultry litter, turkey litter, and feedlot 700°C biochar exhibited the greatest heavy metal retention. In contrast, manure varieties containing disproportionately high (swine) and low (dairy) ash, P, and other elements were the least effective stabilizers. Regardless of the manure type, proton nuclear magnetic resonance analyses showed the removal of leachable aliphatic and nitrogen-containing heteroaromatic functional groups at the higher (700°C) pyrolysis temperature. Consistently greater Cu retention by the 700°C biochar indicated the mobilization of Cu by 350°C biochar-born dissolved organic carbon; however, the influence of other temperature-dependent biochar characteristics cannot be ruled out.     

Heavy metal release from contaminated soils: comparison of column leaching and batch extraction results

Heavy metals in soils may adversely affect environmental quality. In this study, we investigated the release of Zn, Cd, Pb, and Cu from four contaminated soils by column leaching and single and sequential batch extractions. Homogeneously packed soil columns were leached with 67 mL/g 10(-2) M CaCl2 to investigate the exchangeable metal pool and subsequently with 1400 mL/g 10(-2) M CaCl2 adjusted to pH 3 to study the potential of metal release in response to soil acidification. In two noncalcareous soils (pH 5.7 and 5.1), exchange by Ca resulted in pronounced release peaks for Zn and Cd that were coupled to the exchange of Mg by Ca, and 40 to 70% of total Zn and Cd contents were rapidly mobilized. These amounts compared well with exchangeable pools determined in single and sequential batch extractions. In two soils with near-neutral pH, the effluent concentrations of Zn and Cd were several orders of magnitude lower and no pronounced elution peaks were observed. This behavior was also observed for Cu and Pb in all four soils. When the soils were leached at pH 3, the column effluent patterns reflected the coupling of CaCO3 dissolution (if present) and other proton buffering reactions, proton-induced metal release, and metal-specific readsorption within the soil column. Varying the flow rate by a factor of five had only minor effects on the release patterns. Overall, Ca exchange and subsequent acidification to pH 3 removed between 65 and 90% of total Zn, Cd, Pb, and Cu from the four contaminated soils.     

Effects of wood bark and fertilizer amendment on trace element mobility in mine soils, Broken Hill, Australia: implications for mined land reclamation

Soil amendments can immobilize metals in soils, reducing the risks of metal exposure and associated impacts to flora, fauna and human health. In this study, soil amendments were compared, based on "closed system" water extracts, for reducing metal mobility in metal-contaminated soil from the Broken Hill mining center, Australia. Phosphatefertilizer (bovine bone meal, superphosphate, triple superphosphate, potassium orthophosphate) and pine bark (Pinus radiata) were applied to two soils (BH1, BH2) contaminated with mining waste. Both soils had near neutral to alkaline pH values, were sulfide- or sulfate-rich, and contained metal and metalloid at concentrations that pose high environmental risks (e.g., Pb = 1.25 wt% and 0.55 wt%, Zn = 0.71 wt% and 0.47 wt% for BH1 and BH2, respectively). The addition of fertilizers and/or pine bark to both soil types increased water extractable metals and metalloids concentrations (As, Cd, Cu, Fe, Mn, Pb, Sb, Zn) compared with nonamended soils. One or more of the elements As, Cd, Cu, Mn, Pb, and Zn increased significantly in extracts of a range of different soil+pine bark and soil+fertilizer+piner+pine bark tests in response to increased pine bark doses. By contrast, Fe and Sb concentrations in extracts did not change significantly with pine bark addition. Solution pH was decreased by phosphate fertilizers (except for bovine bone meal) and pine bark, and pine bark enhanced dissolved organic carbon. At least in the short-term, the application of phosphate fertilizers and pine bark proved to be an ineffective method for controlling metal and metalloid mobility in soils that contain admixtures of polymetallic, polymineralic mine wastes.     

基于GIS的耕地土壤重金属污染与农业功能定位研究——以山东省聊城市为例

按8km×8km的网格将聊城市耕地分为137个采样点,调查砷、镉、铬、铜、汞、镍、铅、锌等重金属的污染状况。采用国家土壤环境质量标准、农产品安全质量标准和绿色食品产地环境条件作为评价标准,采用单因子指数和综合指数为评价方法进行污染评价。研究表明,聊城市土壤污染强度依次为铜〉镍〉锌〉砷〉铬〉镉〉铅〉汞,但均未超标。以GIS为操作平台显示聊城市重金属空间分布状况,并对区域耕地进行了功能的定位。聊城市西南部土壤质量最优,适宜种植绿色食品;无公害蔬菜和安全粮食种植区在各县市均有不同程度的分布。