Accumulation and solubility of metals during leaf litter decomposition in non-polluted and polluted soil

The decomposition of alder ( Alnus glutinosa ) and poplar ( Populus tremula ) leaf litter placed in direct contact with non-polluted and metal-polluted soil was investigated over 25 months in a controlled model-ecosystem experiment using the litterbag method. In addition to mass loss, we monitored the total and soluble concentrations of carbon, Cu, Zn, Cd and Pb. Leaves from trees grown on polluted soil had larger initial Zn, Cd and dissolved organic carbon concentrations. Neither the origin of the leaves (from trees grown on non-polluted or polluted soil) nor the placement of the leaves in polluted or unpolluted soil affected the decomposition process. Total metal contents increased in leaves placed on polluted soil over time. The solubility of metals in the leaf litter decreased over time, indicating that leaves acted as a temporary pool for metals from the soil in direct contact with the leaves. The sorbed metals were strongly bound in the litter even after two years of decomposition. The strong binding and thus reduced bioavailability of the metals provides an explanation for why they had no observable effects on litter decomposition.     

Impacts of herbivorous insects on decomposer communities during the early stages of primary succession in a semi-arid woodland

Changes in nutrient inputs due to aboveground herbivory may influence the litter and soil microbial community responsible for processes such as decomposition. The mesophyll-feeding scale insect (Matsucoccus acalyptus) found near Sunset Crater National Monument in northern Arizona, USA significantly increases piñon (Pinus edulis) needle litter nitrogen (N) and phosphorus (P) concentrations by 50%, as well as litter inputs to soil by 21%. Because increases in needle litter quality and quantity of this magnitude should affect the microbial communities responsible for decomposition, we tested the hypothesis that insect herbivory causes a shift in soil microbial and litter microarthropod function. Four major findings result from this research: (1) Despite increases in needle inputs due to herbivory, soil carbon (C) was 56% lower beneath scale-susceptible trees than beneath resistant trees; however, soil moisture, N, and pH were similar among treatments. (2) Microbial biomass was 80% lower in soils beneath scale-susceptible trees when compared to resistant trees in the dry season, while microbial enzyme activities were lower beneath susceptible trees in the wet season. (3) Bacterial community-level physiological profiles differed significantly between susceptible and resistant trees during the dry season but not during the wet season. (4) There was a 40% increase in Oribatida and 23% increase in Prostigmata in susceptible needle litter relative to resistant litter. Despite these changes, the magnitude of microbial biomass, activity, and community structure response to herbivory was lower than expected and appears to take a long time to develop. These results suggest that herbivores impact soils in subtle, but important ways; we suggest that while litter chemistry may strongly mediate soil fertility and microbial communities in mesic ecosystems, the influence is lower than expected in this primary succession xeric ecosystem where season mediates differences in microbial populations. Understanding how insect herbivores alter the distribution of susceptible and resistant trees and their associated decomposer communities in arid environments may lead to better prediction of how these ecosystems respond to climatic change.     

Schwermetallgehalte in Waldböden Nordrhein-Westfalens -Klassifizierung und kartographische Auswertung

Heavy metal contents in forest soils of North Rhine-Westphalia - classification and cartographic evaluation Many forest areas in North Rhine-Westphalia (Germany) are contaminated with heavy metals. To evaluate this pollution of forest soils and its geographical distribution all available literature data on total heavy metal contents in forest soils of North Rhine-Westphalia were included in this study. The results show that an accumulation of heavy metals, especially of Pb, occurred in the litter layer and in the litter layer and in the topsoil. The highest values were measured in the vicinity of industrial areas and at elevated locations such as Egge Mountains and Teutoburger Forest. About 50 % of the samples from the litter layer and the topsoil have pH values below 3. 4. Since the translocation of heavy metals in the soil profile at this low pH increases, potential risk from the mobilization of high stores in the litter layer was estimated for several locations of North Rhine-Westphalia.     

Mikrosondenuntersuchungen an unterschiedlich stark mit Schwermetallen belasteten Böden. 2. Gehalte an Schwermetallen und anderen Elementen in Huminstoffaggregationen,Streustoffen und Holzkohlepartikeln

Electron microprobe studies on soil samples with varying heavy metal contamination. 2. Contents of heavy metals and other elements in aggregations of humic substances, litter residues and charcoal particles EMA point analysis show that the organic matter constituents of heavy metal contaminated soils are highly enriched with heavy metals. The maximal trace element accumulation were for Cu up to 13,000 mg/kg, for Zn up to 48,000 mg/kg, for Cd up to 2,100 mg/kg and for Pb up to 193,000 mg/kg. The affinity for the accumulation of the different heavy metals in aggregations of humic substances can be described by the sequence Cu > Pb ? Cd > Zn ? Ni > Co. In very strongly acidified humic top soil horizons the Pb and Cd accumulation in the organic matter constituents is in competition with the accumulation in Fe and Mn oxides. The heavy metal contents (especially of Cu) of the organic matter are often correlated with the content of organically bound calcium. The EMA results also show that high heavy metal amounts occur in combination with Ca-accumulations in the epidermis and the outer bark parenchym of decayed roots. EMA point analysis of the interior of fungus sclerotias show that sclerotias can contain high amounts of heavy metals, in particular lead (up to 49,700 mg Pb/kg). From statistical results of EMA point analysis follows that lead and other heavy metals attached to humic substances are not only bound as metal organic complexes but also as organic metal phosphate complexes. Also charcoal particles of polluted soils contain high amounts of heay metals. The accumulation affinity is quite similar to that of humic substances.     

Spatiotemporal dynamics of the pollution of Al–Fe-humus podzols in the impact zone of a nonferrous metallurgical plant

The dependence of the level of contamination of the upper horizon of Al–Fe-humus podzols (Podzols Rustic) with heavy metals (Ni, Cu) on the distance from the Severonickel smelter (Monchegorsk, Murmansk oblast) was studied on a number of test plots in the medium-aged pine stands. It was found that metal concentrations in the soils could be reasonably approximated by the negative exponential function. In the buffer zone of the smelter, the concentrations of Ni and Cu exceed background values by 8–17 times; in the impact zone, by 50–100 times. The study of the dynamics of acid-soluble forms of Ni and Cu in the organic horizons of podzols on the key plots showed that the boundaries of polluted territory shift towards background regions despite the recent five–eightfold decrease in the emissions. The concentrations of heavy metals in the litter horizons continued to increase in the buffer zone. In the impact zone, their contamination remained at the very high level. Firm bounding of heavy metals in the organic horizon coupled with their continuing aerial input did not allow the beginning of the soil self-purification process, which might last for decades and centuries. Raster electron microscope and X-ray spectral microanalysis showed that particles (>85%) of the ashed matter of organic horizons from the background region, the buffer zone, and the impact zone is mainly represented by various soil-forming minerals and iron oxides (in particular, magnetite). In the samples from the impact zone, about 5% of the mineral particles had the surface morphology and chemical composition typical of dust particles emitted into the air by metal smelters. Most probably, these spherical particles represented magnetite Fe₃O₄ enriched in heavy metals (Cu, Ni).     

河口湿地沉积物中腐殖酸含量对外源重金属分布的影响研究

通过向不同腐殖酸含量的河口湿地沉积物添加人工配制的重金属污染海水,测定污染后沉积物的重金属总量与形态分布,以研究不同腐殖酸含量条件下外源重金属在水-沉积物系统中的转化。结果表明,腐殖酸含量对重金属在沉积物中的吸收量和形态组成有较大的影响,尤其对酸可提取态与可还原态。但是不同重金属之间有一定差别,腐殖酸含量对Cu,Pb的作用较明显,而对Zn,Cd的影响较小。此外,由于河口湿地沉积物处于较高盐度的环境,海水中的离子浓度影响有机质与金属的络合反应,因此与土壤相比,河口湿地沉积物中腐殖酸含量对重金属的生物有效性的影响有所不同。     

Changes in the Spruce Forest Communities Along a Heavy Metal Deposition Gradient on Kola Peninsula

We investigated changes in the community structure of spruce (Picea obovata and P. fennica) forests in the Northern Taiga Region of Russia along a point-source atmospheric deposition gradient of heavy metals on the Kola Peninsula. Study sites were selected in ecologically analogous forest stands at increasing distances from the nickel smelter in Monchegorsk. The heavy metal load at each site was estimated by quantifying metal concentrations in the snow cower. Concentrations of heavy metals in soil, litter and vegetation increased along the gradient of increasing atmospheric deposition. All measured indexes of forest vitality, including species richness and abundance, vertical distribution, and understory structure were adversely affected by pollution.     

Decomposition of Subtropical Fruit Tree Leaf Litter at Nelspruit,South Africa

There is limited information about the decomposition of leaf litter from subtropical fruit trees despite their potential for managing soil fertility. The aim of this study was to quantify the effect of quality on decomposition and nutrient-release patterns from leaf litter of avocado, litchi, and mango trees in South Africa. The litterbag technique was used for investigation. The decomposition results over 2 years indicated significant differences in mass loss among the tree species with low rapid loss for litchi (57.3 percent). The annual decomposition rate constant (k) decreased in the order mango (0.82) > avocado (0.76) > litchi (0.69). The concentrations of phosphorus, potassium, manganese, and polyphenols in all species decreased while nitrogen, sulfur, and calcium concentrations increased with time. The nutrient-release pattern of the leaf litter from the three species varied considerably due to different quality characteristics. This had an influence on litter decomposition and thus its management.     

Authenticity of the traditional cypriot spirit "zivania" on the basis of metal content using a combination of coupled plasma spectroscopy and statistical analysis

Sixty-eight alcoholic beverages ranging in alcoholic degree between 40 and 55 from different countries were analyzed for their 16 most abundant metal elements using inductively coupled plasma (ICP) spectroscopy. The results were analyzed statistically using two different types of analytical methods: canonical discriminant analysis and classification binary trees. The aim of this study was to investigate which of the metals analyzed constitute diagnostic parameters that establish authenticity of the traditional Cypriot spirit zivania. The two statistical methods revealed that Mg, Zn, and Cu are promising distinctive parameters capable of differentiating zivania from other spirits similar in alcoholic degree. It is believed that this differentiation in metals between the alcoholic beverages examined is related to the unique geological and climatic conditions existing on the island of Cyprus.     

广州市流花湖沉积物重金属污染特征及潜在生态风险评估

近年来重金属污染日益加重,对人类及水生态系统健康产生较大危害。本研究选择广州市典型城市湖泊——流花湖,利用地累积指数(Igeo)、潜在生态风险指数(RI)对沉积物中12种重金属的污染水平、垂向分布特征及其潜在生态风险进行评价,并通过多元统计分析对金属元素的来源进行解析。结果表明:①湖泊沉积物重金属含量(Mn、V除外)均显著高于区域土壤背景值,自下而上呈现先增加后减少的趋势;②地累积指数评价结果显示Cd、Zn、Sb、Cu、Pb和As这6种重金属污染较严重,其中Cd偏重度污染的状态(Igeo=3.89);③不同重金属元素污染水平有较大差异,Cd、Cu、Zn、Sb、Pb、As、Ni、Cr、Tl、Co的单个重金属污染指数(Cif)均为中等污染水平以上,而生态风险系数(Eif)表现为Cd(Eif=818.6)极严重等级,Sb(Eif=82.64)重度风险等级,其他10种重金属Eif均为轻度风险等级;④该湖RI指数变化幅度剧烈(105.85相似文献   

赣江中游水源涵养林乔木和蕨类植物凋落物持水和失水特征

选取赣江中游典型水源涵养林中常见的3种常绿针叶树、3种落叶阔叶树、4种常绿阔叶树和5种蕨类植物的凋落叶,通过室内浸泡试验和失水试验研究了植物凋落物的持水和失水特征。结果表明:(1)凋落物的吸水速率均显示出随浸泡时间增加而降低的趋势,到8 h基本趋于平缓,24 h达到饱和状态,而失水速率随着失水时间的增加逐渐减少,到12 h后趋于稳定;(2)蕨类植物凋落物的饱和持水量(202.5%)显著高于落叶阔叶树(173.0%)、常绿阔叶树(124.6%)和常绿针叶树(86.5%),而24 h内蕨类植物的失水量(65.4%)与落叶阔叶树(65.4%)之间没有显著差异,但均高于常绿阔叶树(53.6%)和常绿针叶树(42.8%);(3)凋落物饱和持水量和平均失水速率与其初始密度呈显著负相关(R~2分别为0.428和0.266),而与初始比叶面积呈显著正相关(R~2分别为0.488和0.398),这表明叶密度和比叶面积是决定物种间凋落物持水和失水特征差异的重要因素。研究结果揭示了蕨类植物凋落物在森林水源涵养功能中的重要作用,为赣江中游水源涵养林生态系统服务功能评估和林业管理措施制定提供科技支撑。     

甜瓜中矿物元素分布特征及其相关调控机制研究

为明确甜瓜不同部位24种矿物元素的分布特征及其相关性,本研究以新疆甜瓜为试材,采用电感耦合等离子体质谱(ICP-MS)测定Cu、Ni、Cr、As、Pb、Cd、Fe、Al、Zn、B、Mn、Sr等24种矿物质元素含量,并分析甜瓜中重金属与其他矿物质元素分布特征及其内在相关性。结果表明,甜瓜中矿物元素含量在瓜皮上的富集大于瓜肉中的富集,重金属与微量元素在甜瓜瓜皮与瓜肉的分布表现为两端含量高,越靠近中间含量越低。常量元素在瓜皮的分布表现为两端含量高,越靠近中间含量越低,而在瓜肉中表现为两端含量低,越靠近中间含量越高。多元相关性分析热感图结果表明,Ni与Mo、Cr与Na、As与Na呈中度负相关,其他V、K、P等元素均与重金属元素呈正相关。研究表明,甜瓜不同部位矿物元素富集水平不同,部分元素与重金属的富集具有协同或拮抗作用,后续可通过调控相关元素降低甜瓜重金属富集水平提高甜瓜安全性。     

Assessment and regulation of the ecological state of soils in the impact zone of mining and metallurgical enterprises of Norilsk Nickel Company

An assessment of the ecological state of soils has been performed in the area of mining and metallurgical enterprises of Norilsk Nickel Company with respect to the level of soil contamination by heavy metals, the state of the vegetation, and the biological activity of the soils. The territory within 4 km from Norilsk is characterized by high concentrations of heavy metals, the absence of trees, and the disturbance of the organic matter mineralization. This zone corresponds to level 5 of the loss of environmental quality. At distances of 4–16 km from the city, the state of the environment corresponds to level 4, and, at distances of 16–25 km, to level 3. In the latter zone, the soils are characterized by increased concentrations of acid-soluble and mobile metal compounds, though the concentrations of water-soluble metal compounds do not exceed the maximum permissible levels; the soil microbiological activity is normalized. The state of the environment at a distance of 25 km from Norilsk is close to level 2. Soil contamination with heavy metals is accompanied by a rise in the portion of Cu, Ni, and Co compounds bound with amorphous iron oxides and hydroxides, as well as in the portion of their mobile forms.     

Influence of plants and the microbial activity on the metal content in soil solutions of a soddy-podzolic soil in a model experiment

The influence of plants and microorganisms on the migration of metals in a soddy-podzolic loamy sandy soil was studied in a simulation experiment. It was shown that the biota has a great influence on the release of metal compounds into the soil and lysimetric solutions. In most cases, the metal content was reliably higher in the variants of the experiment with the presence of biota than in the control. The microorganisms maintained a high concentration of metals in the soil solution in the course of the experiment. The influence of the plants on the metal migration begins from the third week of the experiment as the biomass grows. The dose of the introduced metals also influences the concentration of the elements in the solutions and the ratios of the Me in the soil solutions: Me in the lysimetric solutions. In all the variants of the experiment, the ratios become narrower with the increase in the dose; i.e., the migration of the metals becomes more active. The dose of 7 APC (the approximate permissible concentration) has an inhibiting influence on the activity of the microorganisms and mustard plants.     

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。     

基于HDXRF和ICP-MS的黔西北土壤重金属空间分布及影响因素研究

高精度X射线荧光光谱仪(HDXRF)是一种准确度较高的金属元素快速检测仪器。本研究将HDXRF法与电感耦合等离子体质谱(ICP-MS)法进行对比研究，探究HDXRF法在土壤重金属调查评估中的适用性。选取威宁县黑石头镇某地为研究区，基于地理探测器，以土壤理化性质(p H、有机质、CEC、黏粒、粉粒、砂粒)和地形因素(高程、坡度、坡向) 9个因子为自变量，重金属(Cd、Pb、Zn、Cr、Cu、Ni)含量为因变量，分析两种检测方法下耕地土壤重金属空间分布规律及其影响因素。结果表明：6种重金属的HDXRF法与ICP-MS法检测值均服从正态分布，两种方法检测得到的土壤重金属在耕层和剖面的分布规律基本一致，从数据统计上看，仅HDXRF法Cu的值比ICP-MS法高约16%，其他元素无显著差异。HDXRF法与ICP-MS法所测相同重金属间均存在极显著正相关关系(P<0.01)，与各影响因子间相关性分析结果基本一致，Cd、Pb、Zn、Ni与土壤理化性质，Cr与土壤理化性质、高程和坡向，Cu与CEC和高程间均存在极显著相关关系(P<0.01)。地理探测器交互探测结果显示，影响因子间交互作用均显...     

What fraction of the total metal flux into lakes is retained in the sediments?

The concentrations of, and deposition rates for, the pollutant metals (Pb, Cu, Zn, Ni, and Cd) and the rare earth elements are reported for the sediments and settling particulates in a large, remote lake (Lake Opeongo) in the Algonquin Provincial Park, Ontario. Using a mass conservation model based on the rare earth elements, it is estimated that only 40 to 60% of pollutant metals getting into the lake is retained by the sediments. The low retention anada rate may explain the widely reported intra-basin and intra-lake differences in metal contents of sediments and casts some doubt on the use of pollutant metal profiles in retrospective assessment of the human contribution to the metal flux into many lake basins.     

Variations of trace element concentrations in red spruce tree rings

The potential of coniferous trees as biological indicators of heavy metal atmospheric pollution was investigated. In 31 municipalities of an industrialized region, samples of wood from the trunks of red spruce (Picea rubens) were taken to determine the spatial distribution of accumulated metals. Using the annual rings, these core samples were divided into 5-yr sections to determine temporal variations. The concentrations of Mg, Al, Ca, Mn, Fe, Cu, and Zn were measured by neutron activation analysis. All metals showed the highest concentrations in the most recent wood and the bark. For the wood older than 5 yr, Mn and Zn are stable with time, Mg and Ca decrease, while Al, Fe, and Cu appear to increase. A statistical analysis showed the municipalities with the highest variations in metal concentrations; it also revealed correlations in the fluctuations of several of the metals. As expected, trees in towns near metal refineries contain higher amounts of Mn, Fe, and Al. Large variations in metal concentrations, due to factors not totally understood, were observed. Thus, red spruce is not a sensitive bio-indicator of atmospheric metal pollution.     

Leaching of soil‐derived major and trace elements in an arable topsoil after the addition of biochar

The addition of biochar to soils appears to be attractive for sequestering carbon and improving soil fertility. Biochar has been shown to alter carbon, nutrient and element cycling, but there is little information on the cycling of trace elements, which will be introduced increasingly into soils because of their use in modern technologies (e.g. rare earth elements) and significant concentrations in phosphate fertilizers. This study investigated, using column experiments, the effect of biochar addition on the leaching of soil‐derived trace metals from a soil contaminated with heavy metals. The biochar used in this study showed a clear potential to reduce soil‐derived trace metals, including transition metals, rare earth elements and heavy metals such as cadmium (Cd) and lead (Pb), while increasing the amounts of essential nutrients such as potassium (K) and molybdenum (Mo). Uranium was mobilized in the presence of biochar, indicating a risk of increased leaching in biochar‐amended soils. During elution under anoxic conditions manganese (Mn) and iron (Fe) oxides were reduced and a release of metals typically bound to these oxides such as Pb, cobalt (Co), zirconium (Zr) and niobium (Nb) was observed. The retention of dissolved organic matter (DOM) in the amended soil led to a retention of DOM‐associated elements such as copper (Cu), zinc (Zn) and nickel (Ni). Analysis by liquid chromatography followed by ICP‐MS indicated an association with UV‐active DOM. In previous studies conducted with inorganic metal species added to soil, an increased retention of metals has often been interpreted as being caused by cation exchange with the biochar. Our results indicate that the decreased mobility of trace elements is at least partly caused by an enhanced retention of metal‐binding DOM after biochar application.