Streptomyces communities in soils polluted with heavy metals

The contents of differently mobile heavy metal compounds and their influence on the formation of microbial cenoses (particularly, streptomyces communities) in technogenically disturbed soils are considered. Elevated concentrations of mobile Cu, Zn, Ni, Cd, and Fe compounds are shown to determine structural-functional changes in microbial cenoses that are displayed in a decreasing number of microorganisms and a narrower spectrum of the streptomyces species. Some specific features of the formation of streptomyces communities in technogenic soils were revealed on the basis of the analysis of their species structure with the use of the Margalef, Berger-Parker, and Sorensen indices of biodiversity.     

Zinc speciation and isotopic exchangeability in soils polluted with heavy metals

Correct characterization of heavy metal availability is a prerequisite for the management of polluted soils. Our objective was to describe zinc (Zn) availability in polluted soils by measuring the isotopic exchangeability of Zn in soil/solution ( E value) and in soil/plant systems ( L value), by assessing the transfer of Zn and ⁶⁵Zn in the fractions of a six-step selective sequential extraction (SSE) in incubated soils and by identifying Zn forms in soils by means of extended X-ray absorption fine structure (EXAFS) spectroscopy. We distinguished three pools of exchangeable Zn: the pool of Zn exchangeable within 1 minute, which is observed in all soils, Zn exchangeable in the medium term, and the slowly and not exchangeable Zn. The amount of Zn present in the first two pools was similar to the L value measured with Thlaspi caerulescens . The first three steps of the SSE solubilized the first pool and a fraction of the second pool. Most of the second pool and a fraction of the third pool were extracted in the fourth step of the SSE, while the rest of the third pool was extracted in the final steps of the SSE. The EXAFS study conducted on two soils showed that more than half of the Zn was present in species weakly bound to organic compounds and/or outer sphere inorganic and organic complexes. Other species included strongly sorbed Zn species and Zn species in crystalline minerals. The EXAFS study of selected SSE residues showed that the specificity and the efficiency of the extractions depended on the properties of the soil studied.     

Diversity of microorganisms from forest soils differently polluted with heavy metals

Large accumulation of heavy metals in organic layers of forest soils may adversely affect the structure and diversity of microbial communities. The objective of this study was to assess the influence of different soil chemical properties on structure and diversity of microbial communities in soils polluted with different levels of heavy metals. The soil samples were taken at ten sites located in the vicinity of the cities of Legnica and Olkusz, differently polluted with Cu, Zn and Pb. The samples were measured for pH and the contents of organic C (C_org), total N (N_t), total S (S_t) and total Zn, Cu and Pb. The measured gross microbial properties included microbial biomass (C_mic) and soil respiration (RESP). The structure of soil microbial communities was assessed using phospholipid fatty acid (PLFA) analysis and the structure of soil bacterial communities using pyrosequencing of 16S rRNA genes. To assess diversity of the bacterial communities the Chao1 index was calculated based on the pyrosequencing data. For C_mic and RESP the most important factors were N_t and C_org, respectively. The structure and diversity of soil microbial communities revealed by PLFA profiles and pyrosequencing depended mainly on soil pH. The effect of high heavy metal contents on soil microbial properties was weaker compared with other soil properties. High concentrations of heavy metals negatively affected RESP and the Chao1 diversity index. The heavy metal pollution altered the structure of microbial communities measured with PLFA analysis, but the effect of heavy metal pollution was not observed for the structure of soil bacteria measured by pyrosequencing. The obtained results indicate that the use of soil microbial properties to study heavy metal effects may be difficult due to confounding influences of other environmental factors. In large-scale studies local variability of soil properties may obscure the effect of heavy metals.     

Species abundance distribution of collembolan communities in forest soils polluted with heavy metals

The species frequency of collembolan communities along a gradient of heavy metal pollution in soil of pine forest soils was studied. Sampling plots were established in forests 1, 3, 5, 8, 11, 68 and 148 km from the Miasteczko Śląskie zinc smelter. At each plot the plant associations, physicochemical characteristics of soil, and collembolan species composition and abundance were examined. The structure of collembolan communities was analyzed with regard to species distribution, testing geometric series, broken-stick, logarithmic series, log-normal and negative binomial distribution models. Most of the collembolan communities occurring both in contaminated and in uncontaminated soils had structure similar to a negative binomial distribution. In the samples from the oldest forest, the species frequencies could also be fitted to a log-normal distribution. The species frequency model was independent of the degree of soil pollution. Under the assumption of a negative binomial distribution of Collembola from soil samples, it is possible to estimate the theoretical number of collembolan species in the habitats studied. The difference between estimated and empirical numbers of species (the number of species not revealed in samples) was linearly correlated with metal concentrations in soil, indicating the elimination of a number of rare species from severely polluted forests.     

Mobility of heavy metals in pine forest soils as influenced by experimental acidification

The mobility of Pb, Zn, Cd and Cu was examined at two adjacent experimental plots at åmli, southern Norway, B-1 and B-2. Both experiments were established on the same glacifluvial deposits, with forest consisting of uniform stands of Pinus sylvestris L. The forest in B-1 was planted between 1968 and 1970, while B-2 consisted of naturally regenerated trees. The experiments included plots supplied with artificial rain of varying acidity over a period of seven and eight years for B-1 and B-2, respectively, in addition to control plots. In experiment B-1, experimental acidification was carried out both in unlimed plots and in plots applied with three different levels of lime. The two experiments showed distinct differences with respect to effects of the acidification on mobilization of heavy metals from the O horizon. In experiment B-1, the amount of Zn and Cd decreased with decreasing pH in artificial rain, while Pb and Cu were not appreciably affected. The reduction in Zn and Cd concentrations ceased after termination of the acidification experiment. Liming reduced the leachability of Zn, but still appreciable amounts of Zn were obviously leached from the O horizon during the experiment. In experiment B-2 a high retention even of Zn and Cd was observed in the O horizon, probably due to microbial uptake and accumulation.     

Effect of heavy metals on microorganisms in soils near a secondary lead smelter

Soil samples were collected to a depth of 0 to 10 cm from several sites near a secondary Pb smelter during the summer of 1976 in order to determine heavy metal concentrations of soil and enumerate soil microorganisms and earthworms. Chemical analyses indicated that abnormally high concentrations of Pb, As, Cd, and Cu decreased with increasing distance from the source and population counts of bacteria, actinomyces, fungi, nematodes and earthworms increased with increasing distance from the smelter. The negative correlation coefficients between bacteria, actinomyces, fungi, and nematodes and the level of Pb, As, Cd, and Cu in the soil were statistically significant. The microflora of the contaminated soil was altered and the marked quantitative reduction or elimination of organisms were attributable to heavy metal pollution emission from the secondary Pb smelter.     

在法国前铅和锌冶炼厂附近的城市土壤重金属的污染、分离和利用

smelters in Northern France were studied by analysing the chemical forms of these metals and evaluating their phytoavailability. These metals were determined using flame or electrothermal absorption atomic spectrometry （FAAS or ETAAS）, depending on their concentration levels. After optimisation of the ETAAS method, characteristic mass of In in water and aqua regia were 9.9 and 18 pg, respectively, showing the high sensitivity of the analytical Soil contamination by metals from anthropogenic activities （e.g., mining and smelting） is a major concern for the environment and human health. Environmental availability of cadmium （Cd）, lead （Pb）, zinc （Zn）, copper （Cu）, and indium （In） in 27 urban soils located around two former Pb and Zn smelters in Northern France were studied by analysing the chemical forms of these metals and evaluating their phytoavailability. These metals were determined using flame or electrothermal absorption atomic spectrometry （FAAS or ETAAS）, depending on their concentration levels. After optimisation of the ETAAS method, characteristic mass of In in water and aqua regia were 9.9 and 18 pg, respectively, showing the high sensitivity of the analytical procedure. Metal partitioning was conducted using a four-step sequential extraction procedure. The results showed that Cd and Zn were mainly in the acid-extractable and reducible forms in the urban soils studied. In contrast, Pb and In were largely in the reducible fraction. However, in some samples, the amount of In extracted in the residual or exchangeable fraction was higher than that in the reducible fraction. Copper was mainly found in the reducible and residual fractions. A pot experiment was conducted in a glasshouse with seven soils （six contaminated and one uncontaminated） and two plant species, ryegrass and lettuce. The results showed transfer of metals from the contaminated soils to the shoots of ryegrass and the edible part of lettuce. The metal bioconcentration factor was in the order of Cd Cu > In > Zn Pb for lettuce leaves, whereas for ryegrass shoots, three orders were found, Cd > Zn > Cu In > Pb, Cd ≥ In > Zn > Cu Pb, and Zn > Cd > Cu > In > Pb, depending on the physico-chemical properties of the soils, such as pH, cation exchange capacity, carbonates, and organic matter. It was established that the metal toxicity was related to the contamination levels and the physico-chemical properties, including pH, organic matter, and in a lesser extent, Ca, Mg, and phosphorus contents, of the soils. However, it was shown that lettuce could grow on soils having high Cd and CaCO₃ contents. Cadmium was one of the most available metals while Pb was always the least available in the soils studied.     

Extractable heavy metals in Atlantic coast soils

Abstract

The analysis of soils, using 0.1 N HC1 as an extractant for the heavy metals, Cd, Cr, Ni and Pb on “fine”; textured North Shore and “coarse”; textured Annapolis Valley soils was completed. Results show ranges of 0.012 to 0.469 parts per million Cd; 0.102 to 2.90 parts per million Cr; 0.16 to 29.25 parts per million Ni and 0.12 to 244.8 parts per million Pb. Correlation studies indicate that the heavy metal content of fine textured soils is less influenced by changes in clay content and organic matter than are coarse textured soils. Generally the surface layers (0–15 cms) are higher in extractable heavy metal content than the lower layers (15–30 cms).     

Accumulation of heavy metals in oil-contaminated peat soils

X-ray fluorescence and X-ray radiometry represent easy and simple methods to determine concentrations of heavy metals in the ash of peat soils contaminated with oil and can be applied for soil monitoring purposes. Oil spills on peat bogs produce two contamination zones differing in the composition of heavy metals. In the zone of primary contamination, the peat surface is covered by a bitumen crust with V, Ni, Sr, Ba, Ce, and La accumulating there. This zone adjoins the zone of secondary peat contamination, where heavy alkaline-earth metals (Sr, Ba) and lanthanides (Ce and La) are accumulated to a lesser extent. Biological preparations recommended for remediation of oil-contaminated peat soils should be tolerant to high concentrations of heavy metals, particularly, V, Ni, and Ba that are present in the oil contaminated soils in relatively high amounts.     

矿区植物根内嗜鱼外瓶霉对重金属的耐性和超积累作用

从云南会泽铅-锌矿区自然生长植物密序野古草(Arundinella bengalensis(Spreng.)Druce)的健康根内分离得到一株深色有隔内生真菌(dark septate endophytes,DSE)。据其形态学特征和ITS1-5.8S-rDNA-ITS2序列分析,鉴定为一株嗜鱼外瓶霉(Exophiala pisciphila)。纯培养条件下研究了其对Pb2+、Zn2+、Cd2+的耐性和超积累作用。结果表明,此菌株在液体合成培养基上可以分别耐受2、3和0.5 g/L的Pb2+、Zn2+和Cd2+;在含Pb2+、Cd2+培养基中生长其菌丝可以富集超过其干重25%以上的Pb2+和5%以上的Cd2+;显示此菌株属于极端耐性并具有超积累作用的真菌。此真菌在植物根系的定殖或许可以通过菌丝体对金属离子的固持作用缓解植物根围土壤微环境中超量金属离子对植物的毒害作用。     

不同高粱种质对污染土壤中重金属吸收的研究

利用重金属含量较高的污水污染土壤,以未污染土壤作对照,种植8个甜高粱品种、2个饲用高粱品种和1个粒用高粱品种,检测8种重金属在高粱植物体内不同器官的含量,以研究不同高粱种质对重金属的吸收特性。结果表明:甜高粱对汞(Hg)、镉(Cd)、锰(Mn)和锌(Zn)的吸收在两种土壤间差异显著,对钴(Co)、铬(Cr)、铅(Pb)和铜(Cu)的吸收差异不显著。Mn在甜高粱体内含量表现为未污染土壤高于污染土壤;而Zn含量在不同器官之间存在差异,未污染土壤叶中含量远高于穗,穗中含量远高于茎和根。不同重金属在甜高粱体内的储存部位不同,污染土壤上Hg、Cd、Co、Cr和Zn在根中积累量较高,Cu、Mn和Pb在穗中的积累量较高。甜高粱、饲用高粱和粒用高粱对重金属的吸收、运输及储存在品种之间差异较大,同一品种对不同重金属的吸收也存在差异。饲用高粱表现为叶部对Cr和Zn的储存量较高,而粒用高粱‘晋中0823’则显示了茎对多种重金属的储存能力。高粱根对土壤中重金属的富集系数较高,为0.02(Pb)~0.23(Cd),转移系数变幅为0.21(Co)~3.42(Pb)。对同一种重金属的吸收量品种间差异较大,甜高粱‘西蒙’根对Co、Cr、Cu、Mn、Pb和Zn具有高富集系数,粒用高粱‘晋中0823’茎对Hg、Cd、Mn、Pb和Zn富集系数较高。高粱对重金属的吸收能力与转移能力不同步,甜高粱‘绿能1号’具有对多种重金属的高转移能力,粒用高粱‘晋中0823’只对Zn有较高的转移能力。因此本文认为甜高粱对不同重金属的吸收和转移有选择性。对Zn吸收并转移到地上部后,首先储存在叶和穗中,当吸收量足够大时,茎和根也成为储存器官;对Mn的吸收与其他重金属的吸收存在竞争作用,Hg吸收后很少向地上部转移;而对Cu、Mn和Pb吸收后在穗部的储存量较大。饲用高粱与甜高粱相比对重金属的吸收未显示明显的不同,甜高粱‘西蒙’根对多种重金属具有强储存能力,而粒用高粱‘晋中0823’的茎秆显示了比甜高粱更强的储存能力,甜高粱‘绿能1号’对多种重金属的转移能力较强。所以,选择富集和转移能力均强的高粱品种能更有效地吸收土壤中的重金属,达到修复污染土壤的目的。     

Assessment of the migration of heavy metals in soils

Qualitative and quantitative studies of the kinetics and dynamics of technogenic migration of heavy metals (HMs) have been performed in laboratory experiments. It is shown that the redistribution of HMs applied into soils in neutral form has an impulsive pattern. Soil texture does not have a decisive influence on the migration capacity of metals. An important feature of the technogenic migration of HMs is the effect of the polymetallic contamination, upon which the migration capacity of a set of heavy metals is higher than that of separate metal compounds. An index characterizing the ratio of absolute values of migration rates of ionic forms of metals estimated from electrical conductivity values to the rate of infiltration of the soil solution (v_m/v_f) is suggested to estimate the kinetics of HM migration in soils.     

Mobility and leachability of zinc in two soils treated with six organic zinc complexes

A study of soil columns was conducted to evaluate Zn movement potential in two reconstructed soil profiles. Zn-phenolate, Zn-EDDHA, Zn-EDTA, Zn-lignosulfonate, Zn-polyflavonoid, and Zn-heptagluconate were applied in the upper zone of the column. The different physicochemical properties of the two soils and the micronutrient source may influence Zn leaching, the distribution of Zn among soil fractions, and the Zn available to the plant in the depth of the layers. In Aquic Haploxeralf soil, the application of six fertilizers produced little migration and very small leaching of Zn in the soil profiles. In Calcic Haploxeralf soil, Zn-EDTA migrated and was distributed throughout the soil columns. This Zn chelate produces a loss of Zn by leaching, which was 36% of the added Zn. In the latter soil, Zn leached very little with the other five fertilizer treatments. The same as for these organic Zn complexes, the retention of added Zn indicated the potential of metal accumulation in the A(p) horizons of the two soil profiles. A large portion of applied Zn was available to plants [diethylenetriaminepentaacetic acid (DTPA) and Mehlich-3 extractable Zn] in the depths reached by the different commercial formulations. The relationship between the two methods was highly significant (Mehlich-3-Zn = 1.25 + 1.13 DTPA-Zn, R(2) = 99.19%). When Zn was added as Zn-EDTA, the amounts of the most labile fractions (water-soluble plus exchangeable and organically complexed Zn) increased throughout the entire profile column in comparison with the control columns, although in the B(t) horizon of the Aquic Haploxeralf soil they increased only slightly.     

Natural and technogenic compounds of heavy metals in soils

The existing geological classification of heavy metals (HMs) is not suitable for their characterization in soils. The carriers of HMs in soils differ from those in the lithosphere. These are clay minerals; iron oxides, whose composition varies between the background and urban soils; various manganese oxides; and different groups of organic substances. The mineral composition of HM carriers can vary significantly. The main iron oxides are ferrihydrite, goethite, feroxyhyte, and lepidocrocite in the background soils and technogenic magnetite in the urban soils. The different structures of manganese oxides determine their affinity for specific HMs. Metallic iron and green rust are very efficient in artificial geochemical barriers, although they act as strong reducers there. HM compounds strongly vary in soils because of the unstable conditions.     

典型设施栽培土壤重金属含量变化及其风险评价

采用野外调查采样和室内分析相结合的方法,对典型设施栽培地山东寿光的部分土壤重金属含量进行测定,并根据温室蔬菜产地环境质量评价标准,选取单项污染指数法和尼梅罗综合指数法对土壤的重金属污染状况进行了环境质量评价。结果表明,重金属Cu、C r、Pb在设施栽培土壤耕层(0—20 cm)的含量达最大值,显著高于露地土壤;而设施栽培土壤中Zn和Cd的含量分别在20—40 cm和40—60 cm的土层达到最大值,其中Zn含量在0—20 cm和60—80 cm的土层显著高于露地土壤,Cd含量在0—20 cm,40—60 cm,60—80 cm和80—100 cm的土层显著高于露地土壤。从不同使用年限设施栽培土壤中重金属含量变化看出,重金属在设施栽培24~年的土壤中含量最高。对研究区设施栽培土壤重金属含量进行风险评估及分级发现,山东寿光设施土壤耕层主要受到重金属Cd的污染。     

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.     

Mobility of copper and zinc fractions in fungicide-amended vineyard sandy soils

The purpose of this study was to evaluate the mobility of copper (Cu) and zinc (Zn) in the profile and distribution of sandy soil fractions from vineyards. Soil samples were collected from two vineyards of different ages (14 and 30 years) and a natural field area in the south of Brazil. The chemical characteristics, Cu levels and Zn levels, were analyzed in the soils by extraction with ethylenediamine tetraacetic acid (EDTA) using the 3050B method of USEPA and by chemical fractionation. Cu and Zn were accumulated in the vineyard soils, especially in the uppermost soil layers and in the soil from the oldest vineyard. Approximately, 75% of the total Cu was extracted by EDTA, but only 30% of the total Zn was extracted by EDTA. Most of the Cu, especially in the oldest vineyard, was distributed in the mineral-associated fraction, which is characterized by low geochemical mobility, but another important part of the Cu was distributed in the soil organic matter. Most of the Zn in the soil was distributed in the residual and mineral-associated fractions, which are characterized by low mobility and have potential for causing toxicity to plants.     

贵阳市主要土壤重金属状况研究

通过对2000～2003年贵阳市的白云区、修文县、开阳县、清镇市、息烽县、乌当区、小河区以及花溪区的多个旱地的表土和底土（53个样品）中重金属元素（汞、砷、铅、镉、铬）含量进行检测，以GB／T18407．1—2001《农产品安全质量无公害蔬菜产地环境要求》为标准，采用单因子指数法及N．L．Nemerow综合指数法进行评价，分析结果表明：贵阳市无公害蔬菜生产基地的大部分土壤中的5种重金属元素的含量基本在GB／T18407．1—2001规定的范围内，但也有个别区域内土样中砷、镉含量达到了警戒线的含量范围，如白云区底土中砷的单因子综合污染指数达到0．7968、乌当区表土中镉的单因子综合污染指数达到0．7542，两者都属于0．7～1．0污染警戒线范围内。总体土壤的表土、底土重金属综合污染指数分别为0．3785、0．4204，小于0．7，污染等级属于安全，污染水平为清洁，土壤环境质量为1级。     

Mutagenic activity of heavy metals in soils of wayside slopes

The genotoxic properties of soils polluted with heavy metals were studied on two wayside slopes covered with trees in the city of Voronezh. The nucleolar test in cells of the apical meristem of Zebrina pendula Schnizl. roots was used. The genotoxic effect of the soils was revealed according to the increased number of 2-and 3-nucleolar cells (from 41 to 54% and from 19 to 23% in the upper part of the first and second slopes, respectively; in the control, their number was 18 and 7%). The mean number of nucleoli per cell increased from 1.7 to 1.95 in the experiment and 1.31 in the control. The increased vehicle emissions, especially when cars go up the slopes (mainly in the upper and middle parts), correlated with the elevated heavy metal (Pb, Cu, Cd, and Zn) contents in the soil. The mutagenic substances may be removed to the Voronezh Reservoir, where they may be accumulated in some living organisms.     

土壤中重金属离子竞争吸附的研究进展

本文主要对土壤中重金属离子竞争吸附的研究现状进行了综述。讨论了影响重金属离子竞争吸附能力的一些主要因子、吸附平衡模型及吸附反应的动力学过程。重金属离子的一级水解常数、离子半径、电负性等性质及其外界环境条件,如pH值、离子强度、有机质含量等因素影响着离子选择性吸附的强弱。竞争的Langmuir方程和扩展的Freundlich方程被用来对竞争吸附过程进行描述,同时指出竞争吸附过程中存在着一个"过饱和点"。最后,对竞争吸附的发展方向进行了展望,指出应加强理论模型和多因子综合作用影响的研究。