污泥农用对土壤和作物重金属累积及作物产量的影响

以3 a定位试验为基础,比较3种不同处理的污泥肥料（消化污泥、污泥堆肥及污泥复混肥）农田施用下土壤养分、土壤和作物籽粒中Mn、Cu、Zn、Pb、Cd 5种重金属的积累以及作物产量的变化情况,以阐明污泥农用对土壤及作物的影响。研究表明,3种污泥肥料提高了土壤中氮素和有机质的含量;与空白和普通化肥处理相比,3种污泥肥料增加了土壤中Mn和Cu的含量,而对土壤交换态重金属含量没有显著影响;3种污泥处理均增加了小麦籽粒中Zn的含量;相对普通化肥处理,3种污泥肥料处理对小麦和玉米产量均无显著影响。合理施用污泥肥料可以有效地提高作物产量;污泥肥料施用对土壤重金属有一定累积效应,但短期施用对土壤比较安全。     

Effect of Organic Materials on Partitioning,Extractability and Plant Uptake of Metals in an Alum Shale Soil

Soils developed on sulphide-bearing shale (alum shale) in Norway contain naturally high amount of heavy metals. We conducted a greenhouse pot experiment to study the effect of four rates (0, 2, 4, and 8%) and three sources (cow manure, pig manure and peat soil) of organic matter in partitioning and distribution, extractability and plant uptake of Cd, Cu, Ni and Zn in an alum shale soil. Sequential extraction scheme was used to determine the distribution patterns of metals in the soil. DTPA was used for extracting the metals from the soil. Wheat (Triticum aestivum) was used as a test crop to study the plant uptake of metals. The highest amount of Cd was present in the exchangeable fraction, irrespective of the rate and source of organic matter applied. Copper, Ni, and Zn, on the other hand, were present only in small quantities in this fraction. The largest fraction of Cu was associated with organic matter and the amounts present in the oxide, carbonate and exchangeable fractions were very small. Nickel and Zn were found mainly in the residual fraction. Increasing rates of cow and pig manure decreased the amounts of Cd and Ni associated with the exchangeable fraction whereas, the addition of peat soil at the same rate increased the amounts of these metals associated with this fraction. This effect of organic matter was primarily associated with the change in soil pH caused by different organic matter sources. The DTPA-extractable metals were decreased with increasing rates of organic matter application, irrespective of its source. Grain and straw yields of wheat were decreased with increasing rates of organic matter. The application of organic matter increased the Cu and Zn concentrations in both grain and straw. The concentration of all metals was lower in plants grown in the cow manure amended soil as compared to those grown in the soil amended with either pig manure or peat soil. These results sugggest that the source of organic matter was a determining factor for metal distribution in the soil and for metal uptake by plants. In this study cow manure slightly increased the soil pH and thus was more effective than either pig manure or peat soil in reducing the plant uptake of metals but in general the efficiency of the organic material in reducing heavy metal uptake was small.     

肥料重金属含量状况及施肥对土壤和作物重金属富集的影响

本文对肥料中重金属的含量状况以及施肥对土壤和农作物重金属累积影响的研究进展进行了系统分析和总结。过磷酸钙中锌（Zn）、 铜（Cu）、 镉（Cd）、 铅（Pb）含量高于氮肥、 钾肥和三元复合肥,有机-无机复混肥料中的Pb含量高于其他化肥。有机肥如畜禽粪便、 污泥及其堆肥中的重金属含量高于化肥,猪粪中的Cu、 Zn、 砷（As）、 Cd含量明显高于其他有机废弃物,鸡粪中铬（Cr）含量高;污泥和垃圾堆肥中Pb或汞（Hg）含量高。商品有机肥Zn、 Pb和镍（Ni）含量高于堆肥,Hg含量高于畜禽粪便。多数研究表明,氮磷钾配施与不施肥相比土壤Cd和Pb含量增加,施用有机肥比不施肥提高土壤Cu、 Zn、 Pb、 Cd含量。施用化肥对农作物重金属富集的影响不明确,而施用有机肥可提高作物可食部位Cu、 Zn、 Cd、 Pb 的含量,影响大小与有机肥种类、 用量、 土壤类型和pH以及作物种类等有很大关系。在今后的研究中应着重以下几个方面, 1）典型种植体系下土壤重金属的投入/产出平衡; 2）不同种植体系下长期不同施肥措施对土壤重金属含量、 有效性影响的动态趋势; 3）典型种植体系和施肥措施下土壤对重金属的最高承载年限; 4）现有施肥措施下肥料中重金属的最高限量标准。     

Relations Between Soil Properties and Selected Heavy Metal Concentrations in Spring Wheat (Triticum aestivum L.) Grown in Contaminated Soils

Spring wheat was grown in soils near a non-ferrous metals mining and smelting base in Baiyin city, Gansu province, P.R. China. The area studied is 501 km². Some of the croplandshad been contaminated by heavy metals mainly through wastewaterirrigation or aerial deposition. The soil samples were analyzedfor pH, organic matter and available phosphorous (P); also fortotal cadmium (Cd), lead (Pb), copper (Cu) and zinc (Zn) contents. Spring wheat grains were also analyzed for heavy metals. The results were interpreted using multiple linear correlation and stepwise regression analyses. The increment oftotal soil contents of selected heavy metals could enhance grain Cd accumulation, and the increment of total Zn content of soil could lower the grain Pb accumulation. The correlationswere markedly increased by including other soil properties forgrain Cd and Pb. Stepwise regression analyses indicated that the effect of soil pH and available P on the uptake of grain Cd were greater than that of the other total soil contents ofheavy metals. Grain Cd and Pb could be reliably predicted bythe total soil contents of Cd and Pb while the uptake of grainZn and Cu were not satisfactorily predicted.     

Soil management options for Alfisols in the semi-arid tropics: annual and perennial crop production

A field experiment was conducted in the semi arid tropics to study the effects of soil structural modification on cropping systems. The aim was to improve crop production and land resource protection using innovative soil management practices. Tillage, mulch and perennial/annual rotational based systems were compared for 5 years in an Alfisol at ICRISAT in India. Crop yield parameters, including grain and biomass yield, leaf area index, crop cover, and plant height were measured. Results indicate significant benefits to annual crop yield (maize, sorghum) from improved water supply due to mulching with farmyard manure or and rice straw, and due to rotation with prior-perennial crops. Grain yields were 16 to 59% higher in mulched treatments compared to unmulched treatments, with similar increases for fodder yields. Annual crop yields after 4 years of perennials were 14 to 81% higher than unmulched treatments, except for low fertility maize grown after buffel grass. The interaction with chemical fertility was less clear than for water supply. The results have implications for soil management throughout the semi-arid tropics.     

Forms of Cd,Cu, Pb,and Zn in soil and their uptake by cereal crops when applied jointly as carbonates

The cereal crops (barley -Hordeum vulgare L., maize -Zea mays L., wheat -Triticum vulgare L.) were grown in a greenhouse using a sandy soil type treated with various doses of cadmium carbonate (salt), copper carbonate (malachite), lead carbonate (cerussite), and zinc carbonate (smithsonite), added jointly. The following levels of these metals were used: Cd ? 5, 10, 50μg g^?1 soil; Cu and Pb - 50,100, 500 μg g^?1 soil; Zn-150, 300, 1500 μg g-1 soil. Sequential extraction was adopted to partition the metals into five operationally-defined fractions: exchangeable, carbonate, Fe-Mn oxides, organic, and residual. The residual was the most abundant fraction in the untreated (control) soil for all the metals studied (50 to 60% of the total metal content). The concentrations of exchangeable Cd, Cu, Pb, and Zn were relatively low in untreated soil but increased (over the three year period) in treated soils for Cd, Zn, and Cu, whereas only small changes were observed for Ph. This experiment showed a significant increase in Cd, Zn, and Cu in tissue of plants grown on the treated soil, but a non-significant change in plant tissue with respect to Pb concentration.     

华北地区有机种植与常规种植土壤质量比较研究

为探讨有机种植与常规种植两种不同种植方式对土壤质量的影响,本文在华北地区选取典型的有机种植基地与附近相似条件的常规种植地块,比较了不同种植方式下土壤体积质量、土壤中水稳性团聚体及土壤中各养分含量和土壤中7种重金属含量。结果表明:相比常规种植,有机种植降低了土壤体积质量,提高土壤中水稳性大团聚体数量,提高了土壤中水稳性团聚体的MWD值和GMD值,降低了分形维数D,提升了土壤水稳性团聚体稳定性,提高了土壤抗侵蚀的能力。有机种植方式下土壤中有机质含量相比常规种植提高了20%~80%,土壤中速效磷、速效钾、碱解氮和全氮、全磷等养分含量也显著提高,说明有机种植有利于土壤培肥,提高土壤肥力。与土壤背景值相比,土壤中重金属含量有不同程度的增加和积累,曹县有机基地As含量超过土壤环境质量国家一级标准,肃宁有机基地土壤中Cu、Zn含量接近国家一级标准。在调查地区,有机种植降低了土壤中Cr、Cd、Hg污染的威胁,但由于施入有机肥的质量差异,存在重金属Cu、Zn、As富集的风险。相比常规种植,有机种植有利于改善土壤结构,提高土壤综合肥力,土壤中重金属污染的风险主要与施入的有机肥质量有关,有机种植应加强对有机肥源的监控,合理施肥。     

华北地区有机种植和常规种植模式下土壤重金属含量及污染评价

为探讨有机种植与常规种植两种不同种植方式对土壤重金属含量和污染特性的影响,本文在华北5个地区选取典型的有机蔬菜和有机小麦种植基地及附近相似条件的常规种植地块,比较了土壤中Cu、Zn、Pb、Cr、Cd、As共6种重金属含量的差异,并采用不同评价方法对不同种植方式下土壤中重金属的污染程度进行了评价。结果表明:与常规种植相比,有机种植减轻了土壤酸化和盐渍化,提高了土壤有机质含量和阳离子交换量,在一定程度上有利于降低土壤中重金属的生物有效性。与土壤背景值相比,所有调查地区的土壤重金属均有不同程度的增加和积累。与常规种植相比,有机种植模式能有效降低土壤中Cd、Cr含量,有机小麦种植地块因长期施用大量有机肥导致土壤中Cu、Zn、As大量富集;而常规温室菜田同时施用大量的有机肥、化肥及农药,土壤中Cu、Zn、As富集的风险比有机种植模式高;露天蔬菜有机种植地块土壤中Cu、Zn、As含量与常规地块差异不明显。综合污染指数评价结果显示,调查地区土壤均属于轻污染程度,主要贡献因子为Cd、Cu、Zn,有机种植降低了土壤中重金属的综合污染水平;地累积指数法评价结果表明,调查地区处于无污染到中等污染水平,最明显的污染元素是Cd,有机种植降低了土壤中重金属污染的程度和风险;潜在生态危害指数评价结果表明,所调查地块存在轻微潜在生态风险,其中产生较大生态危害的是Cd,表现出轻微生态危害程度。本研究表明,有机种植减轻了土壤中重金属综合污染水平和污染风险,并减轻了土壤重金属的潜在生态危害。     

重金属复合处理对小麦锌铜镍镉积累和分布的影响

为增加粮食可食用部分有益元素的浓度,同时减少有毒重金属元素的含量,需要更好地了解元素在植株和籽粒内的运输和分布。在温室盆栽条件下,以春小麦为供试材料,设置对照（不添加重金属）和重金属复合处理（同时添加铜、锌、镍、镉,以不影响小麦生长为前提）,研究锌（Zn）、铜（Cu）、镍（Ni）、镉（Cd）在成熟植株和籽粒不同部位的分布特点。结果表明,重金属复合处理对小麦成熟期籽粒和秸秆产量、收获指数以及粒重均无显著影响,但使小麦各器官重金属浓度均显著增加,增幅因不同器官和不同元素而异,籽粒中Zn、Cu、Ni和Cd浓度分别增加1.8、0.5、48.1倍和45.3倍。重金属复合处理还显著改变了Zn和Ni在地上部各器官中的分配模式：对照小麦吸收的Zn更易向生殖器官中转运,处理植株则更多地滞留在营养器官中,而Ni呈相反的趋势。激光剥蚀电感耦合等离子体质谱仪（LA-ICP-MS）对籽粒糊粉层和胚乳的定量分析表明,重金属复合处理使糊粉层Zn和Cu浓度仅增加了78%和86%,而糊粉层Ni和Cd浓度分别增加了30倍和121倍。重金属复合处理使胚乳Zn和Cu浓度分别增加了49%和48%,使Ni和Cd浓度均超出小麦标准中Ni和Cd的最大允许浓度（对照籽粒胚乳中没有检验到Ni和Cd）。以上结果表明,在小麦生物强化实践中,在增加有益营养元素（如Cu和Zn）的同时亦存在有毒重金属（如Ni和Cd）超标的巨大风险。     

Relationships Between Heavy Metals Contamination in Shallow Marine Sediments with Industrial and Urban Development in Catalonia (Northwestern Mediterranean Sea)

A total of 179 surface sediment samples from shallow waters have been collected in Catalonia (Northwestern Mediterranean) from 2002 to 2010 to analyze heavy metals (Al, Cd, Cu, Hg, Pb, V, and Zn) concentrations, organic matter content, and sediment size in order (i) to find baseline values, (ii) to investigate metal contamination trends, and (iii) to identify its spatial and temporal distribution. Highest metals concentrations were registered in the Barcelona metropolitan area and in the mouth of Besòs and Llobregat Rivers for Zn, Cu, Pb, and Cd. Mercury was also abundant in these areas but the highest record was found close to Tarragona. The concentrations agree with those reported in other studies performed in big river’s mouths and industrialized areas. The absence of large industrial activity and urbanization outside Barcelona and Tarragona explains the low metal contents found at the other sampling sites. Based on enrichment factor (EF), Pb was the most enriched metal. Results will provide a useful aid for sustainable marine management in Catalonia.     

Bioavailability as a Factor in Risk Assessment of Metal-Contaminated Soil

To accurately assess the risks of metal contaminants in soil, the bioavailability of the metals need to be considered. The bioavailable concentrations determined from homogenized, dried soils are not necessarily representative of in situ conditions of undisturbed field soils. In this study, we investigated the accumulation of metals in wheat (Triticum aestivum) grown in undisturbed contaminated (Pb, Zn, Cu, and Cd) soil cores, in relation to total soil, leachate, and diffusive gradients in thin films (DGT)-labile metal concentrations. Despite the fact that many of the samples contained metal concentrations above guideline values, no significant effects were observed on wheat growth. The bioavailability of metals in the most contaminated samples was estimated to be medium to low, possibly explaining why few effects were observed in the bioassay. For Cu, Zn, and especially for Pb, leachate and DGT-labile concentrations were better predictors of uptake by wheat than total concentrations based on correlations. It is suggested that DGT and leachate concentrations in combination with bioassays in undisturbed soil cores can be used to account for metal bioavailability in soil. These tests could be used during the ecological risk screening stage, in conjunction with total concentrations and guideline values to better estimate receptor exposure.     

Modelling of Cd, Cu, Ni, Pb and Zn uptake, by winter wheat and forage maize, from a sewage disposal farm

Abstract. A predictive model of metal concentrations in crops was developed to optimize soil liming and sludge application strategies at a dedicated sewage sludge disposal site. Predictions of metal concentrations in plant tissue were derived from measured values of soil metal concentration, humus content and soil pH. The plant and soil data used to parameterize the model were collected on site using quadrat sampling of mature crop and underlying topsoil. The uptake model was used to map predicted metal concentrations in wheat grain and forage maize based upon a database of soil characteristics (metal content, % humus and pH) measured as part of a routine geochemical survey of the site. The effect of a management strategy to modify uptake of Cd by wheat by changing soil pH was investigated. The effect of soil dust adhering to maize plants at harvest was also simulated to investigate the importance of this pathway for Cd transfer to animal feed such as silage.
The model gave satisfactory predictions for uptake of Cd and Zn but less useful simulations for Pb, Cu and Ni. The results for Cd uptake showed a greater dependence on soil pH in the case of wheat in comparison to maize. It is suggested that, for the study site, liming to pH 7.0 will reduce Cd concentrations in wheat grain to within EC legal standards. However the Cd content of maize may still exceed these guidelines, with a relatively minor contribution from contamination with soil dust.     

黄棕壤添加重金属的毒性评价及其临界浓度确定

在连续盆栽水稻、小麦的过程中研究了加入黄棕壤的Cu、Cd、Pb的毒性(发光细菌法)。结果表明,当以水提取黄棕壤中三元素,浓度低,不显毒性,这与水提取红壤的结果相反;当以0.1mol L^-1HCI提取黄棕壤中三元素,则浓度明显提高而显示毒性。在相关显著水平P=0.001的基础上建立了土壤金属浓度与剩余发光度(毒性指标)优化拟合方程。规定含金属土壤的临界剩余发光度为90%(EC₁₀)。据此,估算出黄棕壤中Pb、Cu、Cd的临界浓度(μg/g土)分别为:488-587,17.8-25.3,2.11-2.12。     

中国太原市农业土壤的重金属污染状况

To evaluate the current state of the environmental quality of agricultural soils in Taiyuan City, a hotspot for China’s industrial development, the concentrations of 8 heavy metals in soils were investigated by means of extensive sampling in farmlands, forestlands, and grasslands in the city. Statistical analyses and spatial distribution maps were used to identify the most significant heavy metal pollutants. The mean concentrations of As, Cd, Cu, Hg, Pb, Zn, Ni, and Cr were slightly higher than their background values in Taiyuan’s topsoil, but were lower than the maximum permissible concentrations in the Chinese Environmental Quality Standard for agricultural soils. Farmland soils in Taiyuan had the highest average Cd, Cu, Hg, Pb, Zn, and Cr concentrations, but the As and Ni concentrations did not differ significantly among the farmland, forestland, and grasslands. Soil contamination by Cd, Cu, Hg, Pb, Zn, and Cr was mainly derived from farming practices, especially the use of sewage water for irrigation. In contrast, As and Ni might derive mainly from the soil parent material. The identification of heavy metal sources in agricultural soils may provide a basis for taking appropriate action to protect soil quality.     

Changes of Al and Heavy Metal Concentrations in Slovak Soils During the Last 25 Years

The objective of this study was to investigate changes of total concentrations and various extract-defined Al and heavy metal fractions in Slovak agricultural soils during the last 25 years. We compared 7 stored soil samples collected between 1966 and 1970 with samples collected in 1994 at the same sites. Seven fractions of Al, Cd, Cr, Cu, Fe, Mn, Ni, Pb, and Zn were determined with a sequential extraction procedure in all samples. Total concentrations of Cd, Zn, Mn, Ni, and Cu were lower in the 1994 samples; those of Al, Fe, Pb, and Cr were higher. Based on the initial concentrations, the average total concentration changes were: Cd(-10,3%)<Zn(-7,2%)<Mn(-4,8%)<Ni(-2,3%)<Cu(-1,4%)<Al(+2,1%)<Fe(+2,9%)<Cr(+7,4%)<Pb(+8,3%). This row is consistent with the decrease in metal mobility. The differences in salt-extractable metals showed the same pattern; however, changes were more pronounced than for total concentrations. The results suggest that decreases during the last 25 years are caused by higher leaching than deposition rates and increases vice versa. The highest increase in Cr and Pb concentrations is observed in the EDTA-extractable fraction, which mainly characterizes organically bound metals.     

云南滇池沉积物中重金属的形态分布特征

Fractionation of heavy metals in sediments can help in understanding potential hazards of heavy metals. The present study analyzed total concentrations and fractions of selected heavy metals （Cd, Cr, Cu, Pb, and Zn） in surface sediments from Dianchi Lake, Yunnan Province, China, as well as factors that may affect distributions of the various heavy metal fractions. Total concentrations of the heavy metals decreased in the order Zn 〉 Cu 〉 Pb 〉 Cr 〉 Cd. These heavy metals, except Cr, were much higher than their background levels, indicating that Dianchi Lake was polluted by Cd, Zn, Pb, and Cu. Cadmium occurred mainly as the non-residual fraction （sum of the HOAc-soluble, reducible, and oxidizable fractions） （97.6%）, and Zn （55.7%） was also predominantly found in the non-residual fraction. In contrast, most of the Cr （88.5%）, Pb （81.8%）, and Cu （59.2%） occurred in the residual fraction. Correlation analysis showed that total heavy metal concentrations, organic matter and reducible Fe were the main factors affecting the distributions of the various heavy metal fractions. In the Walhai section of Dianchi Lake （comprising 97% of the lake area）, the concentrations of Cd, Zn, Pb, and Cu in the non-residual fraction were significantly lower （P ≤ 0.01 or 0.05） than those of the Caohal section （3% of the lake area）. This indicated that potential heavy metal hazards in the Caohai section were greater than the Waihai section.     

Distribution of Heavy Metals in Near-Shore Sediments of the Swan River Estuary,Western Australia

Estuarine systems adjacent to urban areas are at risk of contamination by contaminants from anthropogenic sources, such as heavy metals. We anticipated that the sediments of the Swan River estuary, which runs through metropolitan Perth in Western Australia, would show metal contamination related to industrialization and inputs of stormwater. Total Cu, Pb and Cd concentrations, and Cu, Pb, Cr and Zn inoperationally-defined fractions, were determined inseparate sampling exercises in near-shore sediments ofthe upper Swan River estuary.Total metal concentrations in sediments were not high (maximum values of 297 mg kg^-1 for Cu, 184 mg kg^-1 for Pb and 0.9 mg kg^-1 for Cd) when compared with Australian environmental assessmentguidelines for soils. On the basis of linear regressions between sediment metal concentrations andphysicochemical properties of the sediments (pH, organic carbon, particle size distribution), no single parameter could explain the variation in metal concentrations for all metals. Sediment organic carbon content was positively correlated with Cu concentration; Cu concentrations also increased significantly with increasing clay content anddecreasing sand content. Pb concentrations showed a significant increase with increasing sediment pH, and were approximately three-fold higher in sediments adjacent to stormwater drain outfalls than in sediments remote from drains; no such effect was observed for Cu or Cd. No effect of distance downstream was observed. Sequential extraction of sediments showed that most of the metals were in relatively immobile forms, for example bound to Feoxides, or only extractable by aqua regia. The enhanced concentrations of Pb near stormwater outfalls suggest that vehicle-derived Pb may be an important contributor of Pb to the estuary.     

Influence of pollution and acidification on metal concentrations in Finnish Lapland lake sediments

Fifteen Finnish Lapland lakes have been investigated to study pollution levels and possible acidification effects on nickel (Ni), copper (Cu), cobalt (Co), zinc (Zn), cadmium (Cd), lead (Pb), manganese (Mn), iron (Fe), potassium (K), sodium (Na), calcium (Ca), magnesium (Mg) and aluminium (Al) concentrations in sediments. Four lakes have average water pH lower than 6.0 and alkalinity lower than 0.050 meq/1. Contamination factor (C_f, ratio of metal concentrations in the uppermost to the deepest layers for a given lake sediment core) of Pb is high, particularly for acidic and acidifying lakes (C_f=5.2–10.4). Ni, Cu, Co, Zn and Cd concentrations increase insignificantly towards sediment surface of some lakes (with a neutral pH) with the rare exception. The influence of passible lake acidification consists of decreasing Cu, Cd, Al, Zn concentrations and organic material contents (loss on ignition) towards the sediment surface. The buffer capacity index (BCI), determined as the ratio of the sum of alkaline and alkaline-earth metals (K, Na, Ca, Mg) to Al, is lower for acidic lakes (from 0.12 to 0.36), whereas for the other lakes the BCI values are higher (from 0.42 to 1.34). Thus, BCI-values, decreased contents of Al, Cd, Zn and Cu, as well as organic matter contents (OMC in the upper lake sediment suggest acidification of freshwater environments.     

Improvement of phytoremediation effects with help of different fertilizer

Abstract

Phytoremediation is increasingly used to remediate metal contaminated soils. However, in order to provide technically efficient phytoremediation of contaminated sites the plant yield and metal uptake have to be enhanced dramatically. The aim of the study was to find appropriate combination of plant species and fertilizers capable of improving yields of the plants and stimulate a transfer of metals to more available to the plants forms. Wheat Triticum vulgare was used for the phytoremediation research. To increase yield of crops and enhance mobility of metals in the rhizosphere the soils were amended with three fertilizers (urea, horse manure, and “ispolin”). Short-term (36 d) vegetation test showed that concentrations of heavy metals in the plants grown in contaminated soil (from site 2) were significantly higher than those in the plants grown in clean soil (from site 1). Growth of wheat resulted in a decrease of Cd content in the soil. Amendment of the contaminated soil with urea enhanced the effect and the decrease of Cd concentration in the soil was more significant. The best effect was demonstrated after application of ispolin: concentrations of Cd, Cu, Pb, and Zn in the rhizosphere decreased 1.2–1.4 times as compared with those in the initial contaminated soil (the decrease was statistically significant).     

Bulk sediment bioassays with five species of fresh-water oligochaetes

The fluxes of metals (Na, K, Ca, Mg, Fe, Mn, Al, Cu, Zn, Pb, Cd, Cr, and Ni) in two spruce forest soils in S. Sweden were quantified using the lysimeter technique. Amounts in precipitation (dry and wet), throughfall, litterfall and annual accumulation in biomass were also quantified, as well as stores in soil and biomass. The metal concentrations of the soil solutions varied greatly according to season. The leaching of some metals (Fe, Cu, Pb, Cr, and organic forms of Al) was associated with the leaching of organic matter. These complexes were leached from the A horizon in considerable amounts. They were precipitated in the upper B horizon and only small amounts were transported further downward. By contrast, the leaching of Na, Mg, Ca, Mn, Cd, Zn, Ni, and inorganic forms of Al increased with increasing soil depth. The concentrations of these metals also increased with increasing soil solution acidity. The highest concentrations were often found at the transition to the C horizon. The amounts of Na, K, Mg, Ca, Mn, Al, Zn, Cd, Cr, and Ni leached from the rooting zone were found to be larger than the amounts deposited from the atmosphere, the main source of these metals being the mineral soil. The reverse was true of Ph, Cu, and Fe, the sink being the upper part of the B horizon.