Sorption and Fractionation of Copper in Soil at a Sewage Irrigation Farm in Australia

Abstract

Copper (Cu) is an important heavy metal to be considered in soil contamination, because high concentrations of copper in soil produce toxic effects and may accumulate in plant tissues. In Australia's oldest sewage irrigation farm, located in Werribee, Victoria, soil in the land filtration area is contaminated by Cu. However, Cu content in herbage tissues is in the normal range and has been trending downward since 1979. Therefore, studies on the sorption capacity and sequential extraction of Cu in soil at the Werribee Farm is of significance, not only for better understanding the mechanism of transport, chemical processes, and plant uptake of Cu, but also in providing information for the practical management of sewage farm soils. Methods of combining sorption isotherms with sequential extraction procedures were adopted, and the results showed that the soil in the land filtration area at Werribee Farm has a high sorption capacity for Cu, and distribution coefficients, K_f of Cu, were 629 L kg^?1 in surface soils (0–20 cm) and 335 L kg^?1 in subsurface soils (20–40 cm). The sequential extraction fractions demonstrate that exchangeable and carbonate fractions are very low, only comprising 3.49 to 5.49% of total copper. The other fractions are also discussed. This characteristic of Cu in soil is related to the low concentration of Cu in plant tissues.     

Extractable Concentrations of Cobalt from Serpentine Soils with Several Single‐Extraction Procedures

In this study, we selected three soil pedons on the shoulder, backslope, and footslope along a serpentine toposequence to measure cobalt (Co) extractability using six single‐extraction procedures. These extraction procedures are distilled water, 0.11 M acetic acid in the first step of the BCR sequential extraction (BCR1), 1 M ammonium acetate (NH₄OAc; pH 7.0), 0.01 M calcium chloride (CaCl₂), diethylenetriamine pentaacetic acid (DTPA), and 0.1 M hydrochloric acid (HCl). Although the Co concentrations in the water extracts of the study soils ranged from 0.15 to 0.93 mg kg^?1, those with HCl extraction can be up to 22.1 mg kg^?1. The extractable Co concentrations in the study soils demonstrate that the extraction capacity is in the order HCl > DTPA > CaCl₂ ? NH₄OAc > BCR1 > H₂O. The percentages of extractable Co after applying the six single‐extraction procedures reveal that Co mobility is greatest in the soils on the backslope, moderate on the footslope, and least mobile on the shoulder.     

Aerobic and anaerobic burning alter trace metal availability in peat soils: evidence from laboratory experiments

As global warming becomes more pronounced, climate change and human activities are leading to frequent peat fire incidents. Fire plays an important role in the environmental distribution of trace metals in peat soils. In the current study, we collected peat soils from six peatlands of the Great Khingan Mountains in Northeast China, where wildfires have often occurred in recent decades. To investigate the transformation of trace metals in peat soils by fire, burning experiments at 250°C (light) or 600°C (severe) and under aerobic (AE, flaming) and anaerobic (AN, smouldering) conditions (AE250, AE600, AN250, AN600) were carried out in the laboratory to investigate the effect of different burning intensities on the distribution of Cu, As, Pb, and Cd in peat soils. The European Community Bureau of Reference (BCR) sequential extraction method for metal fractions was applied for partitioning four fractions (exchangeable, reducible, oxidizable, and residual). The results showed that AE600 significantly decreased the percentages of oxidizable Cu, As, Cd and Pb (Cu_oxi, As_oxi Cd_oxi and Pb_oxi) compared with those of the original samples, e.g., Cu_oxi decreased from 68.84% ± 12.76% to 15.82% ± 8.02% in peat under moss, which might result from organic matter decrease. Under AN250 conditions, the exchangeable As (As_exc) and Pb (Pb_exc) significantly increased by more than twice. Different burning intensities significantly changed the various fractions of Cu, e.g., more than 20% Cu_oxi transferred to exchangeable and reducible fractions as the temperature increased. Most of the available fractions of As transformed to residual As after burning. Our study suggests that the AE600 treatment increased the ecotoxicity and bioavailability of Cu, Pb and Cd in peat soils, while AN250 burning decreased the potential ecotoxicity of Cu, As, and Pb. Compared with lower temperature flaming burning (AE250), the ecotoxicity and bioavailability of Cu and Pb were greater in high temperature (AE600) conditions. Smouldering fires at both temperatures (AN250 and AN600) maintained a high potential ecotoxicity and bioavailability of Cu and Pb in peat soils.     

粤东凤凰山茶区土壤铜、铬化学形态分布及茶叶有效性研究

采用连续化学提取法对粤东凤凰山茶区12个大型茶园共60份土壤样品中Cu和Cr的5种化学形态分布和茶叶有效性进行研究。结果发现,土壤中Cu的5种化学形态的分布规律为残渣态〉有机束缚态〉铁锰氧化态〉碳酸盐态〉交换态,而Cr的化学形态分布为残渣态〉有机束缚态〉交换态〉碳酸盐态〉铁锰氧化态。可交换态Cu和有机束缚态Cu含量与土壤有机质呈显著正相关,而土壤pH值与土壤可交换态Cu呈极显著负相关,与碳酸盐态Cu呈极显著正相关,与有机束缚态Cu和铁锰氧化态Cu呈显著正相关。可交换态Cr含量与土壤有机质呈显著正相关,而土壤pH值与土壤可交换态Cr呈极显著负相关,与碳酸盐态Cr呈极显著正相关。凤凰山茶叶Cu含量的范围在41.20～118.93mg·kg^-1之间,平均为52.92mg·kg^-1。茶叶中Cu含量与土壤可交换态Cu、有机束缚态Cu、有机质都有显著的正相关性,而与土壤pH值有显著的负相关性。茶叶Cr含量的范围在2.73～6.29mg·kg^-1之间,平均为4.13mg·kg^-1。茶叶Cr含量与土壤有机质和pH值分布呈显著正相关和显著负相关。     

Distribution and Availability of Zinc and Copper in Benchmark Soils of Pernambuco State,Brazil

Abstract

The benchmark soils collection of Pernambuco state contain 13 of the 14 soil orders of the Brazilian System of Soil Classification. Thus, information on zinc (Zn) and copper (Cu) status in such soils is useful as a reference of micronutrient distribution and availability in a representative set of Brazilian soils. The present work was performed to assess Zn and Cu distribution into operationally defined fractions of benchmark soils of Pernambuco state. In addition, chemical extractants, with contrasting chemical properties, were used to assess the availability of these micronutrients to relate such values with fertility guidelines concentrations and with the fractions defined by the sequential extraction. The results demonstrated that the organic matter was the most important fraction retaining Zn and Cu in the studied soils, as indicated by the sequential extraction. The Zn availability in the majority of the soils (90% of the samples) is sufficient to meet the requirement of the major field crops, although the available Cu concentrations are below the critical levels for plant growth in 46% of the analyzed samples. Mehlich‐1 extractant appeared to be the most efficient in predicting the availability of Zn in the soils because of its better correlation with exchangeable and organic fractions. DTPA and Mehlich‐3 were the most efficient extractants for the evaluation of Cu availability, as suggested by the better correlation with organic matter, which is the main pool of available Cu in the soils.     

The relationship between copper accumulated in vineyard calcareous soils and soil organic matter and iron

The intensive use for over 100 years of copper sulphate (Bordeaux mixture) to fight mildew in vineyards has led to a substantial accumulation of copper (Cu) in surface soils. To assess the effects of such large concentrations, the surface soils of 10 Burgundy vineyards were sampled and analysed for total organic matter (carbon and nitrogen) and metal (copper and iron) contents. Physical (i.e. size fractionation) and chemical (sequential extraction) methods were used to determine the distribution of these elements. The most Cu‐contaminated plots showed the largest accumulation of organic carbon and Cu in the coarse sand and fine sand fractions. Copper was strongly correlated with organic carbon and organic nitrogen in the coarse sand fraction and with organic nitrogen in the fine sand fraction. Copper was also highly correlated with both Fe and organic nitrogen in the clay fraction but not significantly with organic carbon. The sequential extraction showed that Cu was bound mainly to the Fe oxides. However, in the most Cu‐contaminated plots, a part of added Cu was bound to organic matter. This study suggests that Cu protected indirectly the organic matter present in the coarse fractions against biodegradation, and therefore modified the distribution of organic carbon among the particle‐size fractions. Iron appeared as the main factor responsible for Cu accumulation in the clay fraction, mainly through inclusion of Cu in Fe oxyhydroxides and possibly in clay–humus complexes.     

尾矿库尾砂及周边农田土壤重金属形态分布及其生物有效性

采用BCR（community bureau of reference）连续提取法对大宝山矿山槽对坑尾矿库尾砂和周边农田土壤重金属Cd、Pb、Cu和Zn的形态分布及其生物有效性进行了分析。结果表明,尾砂中Cd、Pb、Cu和Zn残渣态占绝对优势,占其总量的百分数均在85%以上。农田土壤中Cd、Cu和Zn都以残渣态为主,分别占其总量的60%、60%和90%以上,Pb以残渣态和可还原态为主,占其总量的93.44%。农田土壤重金属有效性较尾砂大,尾砂和农田土壤重金属生物有效性均以Pb为最高。     

Sequential and Selective Extraction of Copper in Different Soil Phases and Plant Parts from Former Industrialized Area

Copper (Cu) is an essential trace element for all living organisms; however, excess amounts in soil, plants, and food have negative impacts on the environment and human health. The aim of this study was to determine Cu levels in different chemical phases of soils and the relationship between Cu levels in soil phases and concentrations in plants. Soils and plants grown in these soils from an industrialized area in Turkey were analyzed using a selective and four-stage sequential extraction procedure. Copper levels in exchangeable fractions were found up to 658 mg kg^?1 while total levels were in the range of 133–5609 mg kg^?1. Copper concentrations in plant parts (roots and stem) were in the range of 2.6–240 mg kg^?1. The exchangeable forms of Cu were in the range of 3–22% of total Cu concentrations. The relationships were observed between soil Cu and Rumex plant Cu, and soil Cu and root of Brassicasea plant Cu.     

污染水稻土中重金属的形态分布及其影响因素

通过BCR3步提取法研究了江西省贵溪铜冶炼厂污染区水稻土中重金属的形态分布。研究表明,废渣场渗滤液污染区域(渣场区)的污染较污水灌溉污染区(污灌区)严重,渣场区土壤中Cu、Pb、Cd的含量高于污灌区,而污灌区土壤Ni含量较高。在表层(0～20cm)水稻土中,Cu以可氧化态为主,Pb以可还原态和可氧化态为主,Cd以酸溶态为主,Ni以残渣态为主,不同重金属元素的有效态所占总量百分比大小顺序是Cd>Cu>Pb>Ni。土壤重金属不同形态之间也呈现一定的相关性,说明Cu与Pb、Cd、Ni之间具有同源性。土壤pH主要影响了污灌区中Cu的形态分布,以及渣场区土壤酸溶态Ni的分布。土壤有机质含量对各重金属形态分布的影响不明显。     

Distribution and Transport of Residual Lead and Copper Along Soil Pro?les in a Mining Region of North China

Residual heavy metals are commonly considered to be immobile in soils,leading to an underestimation of their environmental risk.This study investigated the distribution and transport of residual heavy metals along soil pro?les,using the Xiaoqinling gold mining region in North China as a case study.Soil samples were collected at three depths from three locations near the tailing heap.The speciation of copper(Cu) and lead(Pb)(exchangeable,carbonate-bound,Fe-Mn oxide-bound,organic matter-bound,and residual fractions) was determined using a sequential extraction procedure.The residual fraction's morphology was observed using scanning electron microscopy(SEM).Results showed that metal fraction distributions along the soil pro?les were in?uenced by each fraction's mobility.Residual fraction with high chemical stability can not be transformed from or into other fractions.This led to the conclusion that the high concentration of residual metals in soils mainly resulted from residual fraction transport.The SEM analysis showed that ?ne particles(submicrons) were mainly attached to large particles and were likely released and transported by water?ow.The more sorptive fractions(non-residual fractions) were mainly retained in the top soil,and the more mobile fractions(residual fraction) were mainly leached to the deep soil.Cu and Pb concentrations in the residual fraction decreased slightly and those in the non-residual fractions decreased signi?cantly with soil depth.These suggest a relatively higher residual metal mobility along the soil pro?les.Therefore,residual metals can be transported in soils and their environmental risk can not be ignored in assessing soil contamination.     

Concentrations and forms of heavy metals in Slovak soils

The risk assessment of heavy‐metal contamination in soils requires knowledge of the controls of metal concentrations and speciation. We tested the relationship between soil properties (pH, CEC, C_org, oxide concentrations, texture) and land use (forest, grassland, arable) and the partitioning of Al, Cd, Cr, Cu, Fe, Mn, Ni, Pb, and Zn among the seven fractions of a sequential extraction procedure in 146 A horizons from Slovakia. Using a cluster analysis, we identified 92 soils as representing background metal concentrations while the remaining 54 soils showed anthropogenic contamination. Among the background soils, forest soils had the lowest heavy‐metal concentrations except for Pb (highest), because of the shielding effect of the organic layer. Arable soils had the highest Cr, Cu, and Ni concentrations suggesting metal input with agrochemicals. Grassland soils had the highest Cd and Zn concentrations probably for geogenic reasons. Besides the parent material (highest metal concentrations in soils from carbonatic rock, lowest in quartz‐rich soils with sandy texture), pedogenic eluviation processes controlled metal concentrations with podzols showing depletion of most metals in E horizons. Partitioning among the seven fractions of the sequential extraction procedure was element‐specific. The pH was the overwhelming control of the contributions of the bioavailable fractions (fractions 1–4) of all metals and even influenced the contributions of Fe oxide‐associated metals (fractions 5 and 6) to total metal concentrations. For fractions 5 and 6, Fe concentrations in oxides were the most important control of contributions to total metal concentrations. After statistically separating the pH from land use, we found that the contributions of Cu in fractions 1–4 and of NH₄NO₃‐extractable Al, Cd, Pb, and Zn to total metal concentrations were significantly higher under forest than under grassland and in some cases arable use. Our results confirm that metal speciation in soils is mainly controlled by the pH. Furthermore, land use has a significant effect.     

Ambient nitrous oxide emissions from different landform complexes as affected by simulated rain‐fall

Abstract

The Tesponse of ambient nitrous oxide (N₂O) emissions to four levels of simulated rainfall (5, 10, 20, and 40 mm) was assessed using large‐diameter cores of undisturbed soil in a greenhouse. The soil cores were taken from the two dominant soil‐landform groups present in the study area: Mollic Albaqualfs in footslope complexes and Typic Haploborolls in shoulder complexes. The footslope complexes had higher ambient N₂O emission than the shoulder complexes at all rainfall levels which was attributed to the differences in inherent characteristics of the soils occurring at these landscape positions. This demonstrates the importance of a spatially‐based investigative approach to account for landscape‐scale differences in soil characteristics when investigating N₂O emission at a large scale. Rainfall level strongly influenced the aeration status of the soil which, in turn, affected N₂O emission. Rainfall showed to be a potential suitable parameter in a predictive model for N₂O emissions (R² = 0.73** and 0.57** on the footslope and shoulder complexes, respectively). Nitrous oxide emissions also occurred in bursts following high rainfall levels; major increases were observed following 20 and 40 mm rainfall. At these rainfall levels, the N₂O fluxes from the footslope and shoulder complexes returned to the background level after 48 h and 24 h, respectively. In addition to an appropriate spatial sampling scheme, this study also illustrates the importance of rainfall in deriving a reliable temporal sampling scheme that would include rainfall‐induced episodic emissions to obtain meaningful N₂O flux estimates. The potential of using rainfall data for predicting N₂O emission activity warrants further investigation under actual field condition.     

PARTITIONING OF HEAVY METALS IN PODZOL SOILS CONTAMINATED BY MINE DRAINAGE WATERS,DALARNA, SWEDEN

The discharge of acidic mine drainage waters onto a hillslope in Dalarna, central Sweden, has lead to the contamination of the podzol soils with Cu, Fe, Ni, Pb, Zn and sulfate. Samples from contaminated and reference soils have been collected for chemical and mineralogical analyses. Jarosite is identified by x-ray diffraction analysis as a precipitate in the upper horizons (A, E, B) of the contaminated soils, where the soil acidity (pH_KCl～2.6) promotes jarosite stability. The sequential chemical extraction of soil samples indicates that, in the reference A horizon, Cu, Pb, Ni and Zn are bound primarily to cation exchange sites and organic matter. In the A horizon of the contaminated soils closest to the rock dump, metal partitioning is dominated by the Fe oxide fractions, despite the high organic matter content; Pb is almost completely bound to crystalline Fe oxides, possibly adsorbed to Fe oxides or occuring in a jarosite solid solution. In the reference B and C horizons, Cu, Ni and Zn are primarily adsorbed/coprecipitated in the Fe oxide fractions, while Pb remains with a large fraction bound to organic matter. In the Fe-rich B horizon of the contaminated soils, the partitioning of the metals in cation exchange sites and to organic matter has greatly increased relative to the reference soils, resulting from the mobilization of organo-metal complexes down the profile.     

Retention of copper, cadmium and zinc in soil and its textural fractions influenced by long-term field management

The present study investigated the impact of long‐term soil management on the metal retention capacity of soil. We examined the sorption behaviour of Cu, Cd and Zn in soils and in the various particle‐size fractions of these soils, which had been amended with farmyard manure, mineral fertilizers or were fallow for 38 years in a long‐term field experiment. The soils investigated contained different amounts and origins of organic matter and differed in soil pH, but the mineral phase showed less response to the different soil managements. Batch adsorption and desorption experiments as well as a sequential fractionation schema, which defines seven geochemical fractions, were used to investigate the retention properties of soil. Sequential extraction was conducted with original as well as with metal‐spiked soils. Results showed that amounts of Cu, Cd and Zn retained differed by a factor of more than 3 among the treatments in the long‐term field experiment, when a massive concentration of metal was added to soil. An increased sorption on smaller particle size fractions occurred (clay ≫ silt > fine sand ≥ coarse sand) due to the larger surface area as well as the greater carbon content in the smaller fractions. Soil sorption behaviour in another long‐term field experiment was estimated based on the present particle‐sorption data. Differences in the sorption behaviour were related to differences in soil mineralogy and amounts of Fe‐ and Mn‐oxides. Fractionation of the original and the metal‐spiked soil underlined the contribution of organic matter to sorption capacity (sequence: Cu ≫ Cd > Zn). Different organic matter contents and a different soil pH considerably changed the amounts of metals in the defined geochemical fractions. Freshly added Cu, Cd and Zn ions were found mainly in more mobile fractions. In contrast, metals in non‐spiked soils appeared in less‐mobile fractions reflecting their long‐term sorption behaviour.     

A critical assessment on arsenic partitioning in mine-affected soils by using two sequential extraction protocols

The highly degraded mine-affected soils of Lavrion, central Greece, are greatly polluted by heavy metals and arsenic (As). To assess As partitioning in the soils of the area, Wenzel and BCR (Community Bureau of Reference) sequential extraction procedures (SEP) were applied to 29 top soils. The results of the Wenzel SEP showed that As was mainly bound to the well-crystallized (33.3%) and to the amorphous/poorly-crystalline (30.1%) oxides of Fe, Al, and Mn. According to the BCR scheme, most of the total As (78.4%) was retained in the residual phase. Low mobility factor values (Wenzel: 0.34%; BCR: 1.56%) clearly demonstrate the low availability and mobility of As in the studied soils. The specifically-sorbed/inner-sphere and the reducible fractions of As, obtained by the Wenzel SEP, were positively correlated with clay and Fe oxides content, respectively. The reducible As fractions of both SEPs were negatively correlated with carbonates content indicating that carbonates may partially control As sorption on Fe oxides. The comparative evaluation of the two SEPs showed that the application of the BCR protocol in contaminated soils cannot provide reliable information on As sequestration in soils but it can be a first estimate of As labile forms.     

Redistribution and Availability of Iron,Manganese, Zinc,and Copper in Four Malian Agricultural Soils Amended with Solid Municipal Waste Compost

Abstract

Municipal waste compost can improve the fertility status of tropical soils. The redistribution of iron (Fe), manganese (Mn), zinc (Zn), and copper (Cu) in tropical soils after amendment with solid municipal waste compost was investigated. Four tropical agricultural soils from Mali characterized by poor trace‐element status were amended with compost and incubated for 32 weeks at 35°C. The soil were analyzed at the beginning and the end of the incubation experiment for readily available fractions, organic fractions, and residual fractions as operationally defined by sequential extraction. Readily available Fe increased significantly with compost application in most soils. Readily available Mn was mostly unaffected by compost application. After 32 weeks, readily available Zn had increased, and readily available Cu had decreased. Readily available levels of the elements remained greater than deficiency levels in the compost‐amended soils. Organic fractions of the elements increased after compost addition. The organic fractions and residual forms, depending on the element and the soil, remained constant or increased within the duration of the experiment.     

Fractionation of tropical soilborne heavy metals—Comparison of two sequential extraction procedures

We compared Cr, Cu, Ni and Zn fractionation patterns in four typical soils naturally containing high levels of these elements on the tropical volcanic island of Réunion. Two sequential chemical extraction procedures were used: the modified four-stage BCR procedure (subsequently called mBCR) and the modified six-stage Geological Survey of Canada procedure (subsequently called mGSC). The results obtained by these two procedures highlighted some similarities. With both approaches, exchangeable fractions were the smallest fractions with respect to the four heavy metal (HM) distributions (< 5% of the total HM quantity), and residual fractions had the highest Cr, Cu, Ni and Zn contents (39.1–97.9%) in the four soils. In contrast, we noted differences in HM fractions bound to organic matter. These differences could be explained by the different reagents and extraction sequences implemented in the two procedures. However, the most marked difference in the results obtained by the two procedures concerned the HM fraction bound to oxyhydroxides, despite the fact that the same reagent was used (hydroxylammonium chloride). Our results revealed that the mBCR procedure underestimated the proportion of HM bound to this fraction. The mGSC procedure therefore seems more suitable for analysing tropical soils which typically contain high levels of Fe and Mn oxyhydroxides.     

Arsenic adsorption by soils and iron-oxide-coated sand: kinetics and reversibility

Arsenic has recently received increasing attention due to its high toxicity and to the possible risks for human and environmental health associated with As-polluted soils. The present work deals with the kinetics and reversibility of As sorption by Fe-oxide-coated sand (IOCS) and soils with different chemical and physical characteristics. Soils and IOCS were equilibrated for five different periods of time with solutions containing As (III) and/or (V) in order to study the kinetics of As adsorption. After 1, 10 and 30 days of equilibration soils and IOCS were sequentially extracted to assess the effect of aging on the binding forms of As. The kinetics of arsenite and arsenate adsorption varied among the soils as a result of differential soil characteristics. The conversion of As to less mobile forms was demonstrated using a sequential extraction. The amount of As extracted with weaker extractants decreased with time whereas the amount of As in more recalcitrant fractions increased. This conversion is expected to render As less mobile and toxic with time after addition to the soil.     

干旱区绿洲灌漠土对铜的吸附解吸特性研究

土壤对重金属的吸附解吸是影响土壤系统中重金属的移动性和归宿的主要过程.本文使用序批实验方法、单步提取方法、连续提取方法等研究了干旱区绿洲灌漠土Cu的吸附解吸特性.结果表明,灌漠土对Cu的吸附等温线可很好地用Freundlich等温方程拟合,灌漠土的Cu吸附可能受土壤理化综合因素影响,而不仅是某个土壤理化指标所控制;二次...     

DISTRIBUTION AND PHYTOAVAILABILITY PREDICTION OF ZINC IN AGRICULTURAL CALCAREOUS SOILS

The extractability and distributions of zinc (Zn) were evaluated in calcareous agricultural soils from South-West Iran. Both single [diethylenetriaminepentaacetic acid (DTPA)] and sequential extraction procedures (Singh scheme) were applied to 20 representative soils. The DTPA extractable zinc levels were low (on average 3.34%). The sequential extraction procedures were also utilized for the study of zinc phytoavailability in maize plants (Zea mays L.) in a greenhouse experiment. The Singh scheme was significantly better than DTPA plus soil properties in phytoavailability prediction of zinc in soils. Significant correlations were found between the amounts of DTPA extractable zinc and the iron (Fe) oxides-bound (AFe and CFe) and residual fractions extracted by the Singh procedure. Zinc concentrations in plant samples (mean value of 27.49 mg kg^?1) were poorly correlated with the different extracted soil fractions (single and sequential). The Singh procedure provided better predictions of zinc uptake by plants than DTPA extraction method.