Mercury contamination in agricultural soils from abandoned metal mines classified by geology and mineralization

Lead (Pb) contents and partition in soils collected from eleven vegetable-growing lands in Fujian Province, China, were investigated using a modification of the BCR (Community Bureau of Reference) sequential extraction procedure coupled with the Pb isotope ratio technique. Pb contents in Chinese white cabbage (B. Chinensis L.) grown on the lands for this study were also measured. Results showed that Pb concentrations in fifty samples of topsoil ranged from 456 to 21.5 mg kg⁻¹, with each mean concentration of six sampling lands exceeding the national standard (50 mg kg⁻¹); while Pb concentrations in edible portions of thirty-two vegetable samples ranged from 0.009 to 2.20 mg kg⁻¹, with four sampling sites exceeding the national sanitary standard (0.2 mg kg⁻¹). A significant correlation (r = 0.971, P < 0.01) of Pb contents in the acid-extractable fractions by BCR approach and the vegetables was observed, which indicates that the acid-extractable Pb is useful for evaluating the metal bioavailability for plants and potential risk for human health in soils. The determination of lead isotope ratios in different chemical forms of soils by BCR sequential extraction procedures provides useful information on the Pb isotopic composition associated with different soil fractions (especially in the acid-extractable fractions), and the result is helpful for the further study on controlling and reducing Pb contamination in vegetable-growing soils.     

Mercury contamination in agricultural soils from abandoned metal mines classified by geology and mineralization

The concentrations and loadings of major and trace elements in coal mine drainage (CMD) from 49 abandoned mines located in the coal fields of the Brazilian state of Santa Catarina were determined. The CMD sites typically displayed a wide spatial and temporal variability in physical and geochemical conditions. The results of our CMD analyses in Santa Catarina State were used to illustrate that the geochemical processes in the rock piles can be deduced from multiple data sets. The observed relationship between the pH and constituent concentrations were attributed to (1) dilution of acidic water by near-neutral or alkaline groundwater and (2) solubility control of Al, Fe, Mn, Ba and Sr by hydroxide, sulfate, and/or carbonate minerals. The preliminary results of the CMD analyses and environmental health in the Santa Catarina region, Brazil, are discussed.     

Mercury contamination in agricultural soils from abandoned metal mines classified by geology and mineralization

This survey aimed to compare mercury concentrations in soils related to geology and mineralization types of mines. A total of 16,386 surface soils (0~15 cm in depth) were taken from agricultural lands near 343 abandoned mines (within 2 km from each mine) and analyzed for Hg by AAS with a hydride-generation device. To meaningfully compare mercury levels in soils with geology and mineralization types, three subclassification criteria were adapted: (1) five mineralization types, (2) four valuable ore mineral types, and (3) four parent rock types. The average concentration of Hg in all soils was 0.204 mg kg(-1) with a range of 0.002-24.07 mg kg(-1). Based on the mineralization types, average Hg concentrations (mg kg(-1)) in the soils decreased in the order of pegmatite (0.250) > hydrothermal vein (0.208) > hydrothermal replacement (0.166) > skarn (0.121) > sedimentary deposits (0.045). In terms of the valuable ore mineral types, the concentrations decreased in the order of Au-Ag-base metal mines ≈ base metal mines > Au-Ag mines > Sn-W-Mo-Fe-Mn mines. For parent rock types, similar concentrations were found in the soils derived from sedimentary rocks and metamorphic rocks followed by heterogeneous rocks with igneous and metamorphic processes. Furthermore, farmland soils contained relatively higher Hg levels than paddy soils. Therefore, it can be concluded that soils in Au, Ag, and base metal mines derived from a hydrothermal vein type of metamorphic rocks and pegmatite deposits contained relatively higher concentrations of mercury in the surface environment.     

温度和氮素输入对青藏高原三种高寒草地土壤碳矿化的影响

选取了海北高寒草甸、那曲高寒草原和当雄高寒湿地3种典型高寒草地生态系统类型为研究对象,采集了表层0~10 cm土壤,在实验室内进行可控温度下的碳矿化培养实验。结果表明,青藏高原土壤碳矿化在不同高寒草地类型间存在显著差异（P≤0.05）。在较低的温度下,高寒湿地土壤的碳矿化速率显著低于高寒草甸土壤,而温度在15℃左右时,高寒湿地土的碳矿化速率略高于高寒草甸土壤,当温度处于较高的水平时（〉20℃）,高寒湿地土壤碳矿化速率远高于高寒草甸土壤,高寒湿地土壤碳矿化的Q10显著大于高寒草甸。无论是低温还是较高的温度,高寒草原土壤碳矿化速率最低,数值范围也最窄。高寒草甸和高寒湿地土壤碳矿化均受温度的显著影响（P≤0.05）,其速率均跟温度呈现一级指数函数方程关系,而高寒草原土壤碳矿化速率与温度间未呈现明显的函数关系,但不同温度间的土壤碳矿化速率存在显著差异。氮素输入对高寒草甸和高寒湿地土壤碳矿化的影响不明显,但显著促进了高寒草原土壤碳矿化作用。     

太湖地区水稻土有机氮厌氧矿化的温度效应

采用淹水密闭培养法研究了太湖地区六种典型水稻土在不同温度下的有机N厌氧矿化过程.结果表明,在28天的培养实验中,当温度设置为1535 ℃时水稻土的矿化量为全N含量的3.33%9.06% ( N 48105 mg·kg-1).随温度升高土壤矿化量增大,在30 ℃时达最大值.温度和土壤类型的差异造成矿化量的差别.选用有效积温式、One-pool、Two-pool和Special模型对有机N矿化进行了拟合,非线性拟合表明Special模型对矿化过程拟合最好,Two-pool模型等同于One-pool模型,不具意义.运用不同温度下One-pool和Special模型中的速率常数得到的Arrhenius方程能较好反映温度效应.温度效应系数Q10 在不同的温度范围内差别较大,显示了易矿化部分与有机氮整体矿化对温度变化的响应.     

外源污染物对蚯蚓毒理作用研究进展

以蚯蚓为模式生物,研究环境污染物的生物效应及其对土壤生态系统的影响,已成为国内外的研究热点.蚯蚓受到污染胁迫时,在分子、细胞和生理水平上都会发生明显的变化,进而影响其存活、生长和繁殖能力,最终引起种群及群落的变化.在总结国内外相关研究基础上,从微观水平、个体水平及生态水平3个方面综述和分析了重金属、农药等外源污染物对蚯蚓毒理作用的研究进展,并对未来的研究方向进行了展望.     

Earthworms and legumes control litter decomposition in a plant diversity gradient

The role of species and functional group diversity of primary producers for decomposers and decomposition processes is little understood. We made use of the "Jena Biodiversity Experiment" and tested the hypothesis that increasing plant species (1, 4, and 16 species) and functional group diversity (1, 2, 3, and 4 groups) beneficially affects decomposer density and activity and therefore the decomposition of plant litter material. Furthermore, by manipulating the densities of decomposers (earthworms and springtails) within the plant diversity gradient we investigated how the interactions between plant diversity and decomposer densities affect the decomposition of litter belonging to different plant functional groups (grasses, herbs, and legumes). Positive effects of increasing plant species or functional group diversity on earthworms (biomass and density) and microbial biomass were mainly due to the increased incidence of legumes with increasing diversity. Neither plant species diversity nor functional group diversity affected litter decomposition, However, litter decomposition varied with decomposer and plant functional group identity (of both living plants and plant litter). While springtail removal generally had little effect on decomposition, increased earthworm density accelerated the decomposition of nitrogen-rich legume litter, and this was more pronounced at higher plant diversity. The results suggest that earthworms (Lumbricus terrestris L.) and legumes function as keystone organisms for grassland decomposition processes and presumably contribute to the recorded increase in primary productivity with increasing plant diversity.     

猪粪、木屑混合物蚯蚓堆制处理中蚓体Cu、Zn富集的影响因素

采用室内接种法,以赤子爱胜蚓（Eisenia fetida）构建生物反应器,研究猪粪、木屑混合物的蚯蚓堆制处理中,蚓体的生长状况及影响其Cu、Zn富集的主要因素。结果表明,接种密度为40 mg.g-1、湿度为75%同时有利于蚯蚓生长和基质消耗;温度为15℃对蚓体质量增加最有利,而温度为20℃最利于基质消耗;m（猪粪）∶m（木屑）为6∶4可同时利于蚓体质量增加和基质消耗。适宜的接种密度（48 mg.g-1）、湿度（70%）、温度（15℃）及较高比例的碳源辅料〔m（猪粪）∶m（木屑）为6∶4〕有利于蚓体对Cu的吸收和富集;低接种密度和高比例碳源辅料有利于蚓体对Zn的吸收,湿度和温度对蚓体Zn含量无显著影响,但蚓体Zn富集量分别在接种密度48 mg.g-1、m（猪粪）∶m（木屑）为6∶4、湿度75%和温度15℃条件下达最大。     

二氧化锰体系中环丙沙星的氧化转化研究

为了更全面的了解环丙沙星在自然界中的环境化学行为,采用批处理实验方法研究了环丙沙星在二氧化锰作用下的氧化转化过程,并讨论了溶液的pH对反应的影响。结果表明,在无二氧化锰的条件下,环丙沙星的质量浓度在1周内检测没有明显的变化。在二氧化锰存在的条件下,环丙沙星对二氧化锰的氧化作用具有较强的反应感受性。pH一定的条件下,当环丙沙星相对过量时,环丙沙星去除率随自身质量浓度的增大而减小,随二氧化锰质量浓度的增大而增大。此外,随着溶液pH值由3.5升至5.9时,环丙沙星的去除率显著上升。     

二氧化锰体系中环丙沙星的氧化转化研究

为了更全面的了解环丙沙星在自然界中的环境化学行为,采用批处理实验方法研究了环丙沙星在二氧化锰作用下的氧化转化过程,并讨论了溶液的pH对反应的影响。结果表明,在无二氧化锰的条件下,环丙沙星的质量浓度在1周内检测没有明显的变化。在二氧化锰存在的条件下,环丙沙星对二氧化锰的氧化作用具有较强的反应感受性。pH一定的条件下,当环丙沙星相对过量时,环丙沙星去除率随自身质量浓度的增大而减小,随二氧化锰质量浓度的增大而增大。此外,随着溶液pH值由3.5升至5.9时,环丙沙星的去除率显著上升。     

Photocatalytic degradation of ciprofloxacin in aqueous media: a short review

The frequent detection of antibiotics such as ciprofloxacin in surface and drinking waters around the world has attracted concern from various researchers. Such presence is an indication that the decontamination of water polluted by antibiotics is beyond the conventional treatment methods. However, among the different treatment methods that have been developed in the area of water purification, heterogeneous photocatalysis using semiconductor as a mediator has been rated as an efficient and a green wastewater treatment method. This is because, the process is effective in degrading and mineralizing organic pollutants, using UV or visible light. The present review paper covers a brief survey over a range of publications in the last decade, involving photocatalytic materials that have been employed in the purification of water contaminated by ciprofloxacin.     

Bioavailability and accumulation of trace elements in soils and plants of a highly contaminated estuary (Domingo Rubio tidal channel,SW Spain)

The Domingo Rubio tidal channel (Palos de la Frontera, Huelva, Spain) is an estuary located in the mouth of the Tinto River. The estuary is affected by different sources of pollution (waters of the Tinto River, contaminated with trace elements from the Iberian Pyrite belt, and effluent from the Huelva chemical industrial area). Soil and the most frequent plant species were collected in 2004 and 2006 at six different locations on the estuary. In general, N-Kjedahl, Total Organic Carbon values, salinity and contamination (total trace elements up to 1,000 mg kg⁻¹ As, 6 mg kg⁻¹ Cd, 2,500 mg kg⁻¹ Cu, 1,900 mg kg⁻¹ Pb and 1,300 mg kg⁻¹ Zn) tended to increase downstream of the tidal channel. Soil biochemical properties were not negatively affected either by the high salinity or by trace element contamination. Despite the high values of the trace elements, analysed plant samples showed that Cu was the only metal that could be a serious risk for the food chain.     

接种蚯蚓对红壤氮素矿化特征的影响

在室内恒温培养、间歇破坏性采样的条件下,研究了蚯蚓活动对红壤氮素矿化以及土壤氮素肥力的影响。试验共设置以下四个处理:(1)不接种蚯蚓不施用秸秆的对照处理(S);(2)单接种蚯蚓处理(E);(3)单施秸秆处理(O);(4)蚯蚓 秸秆处理(OE)。分别于培养后的第6,12,18,24,30d进行5次破坏性采样。试验结果显示:在整个培养时期中,无论是否施用秸秆,接种蚯蚓处理(E,OE)的土壤铵态氮含量均较同期相应对照处理(S,O)有显著性提高(p<0.05),到培养结束时,铵态氮含量分别是相应对照处理(S,O)的9.27倍和6.76倍。通过计算不同培养期土壤氮素的矿化速率和累积矿化速率发现,无论有无施用秸秆,接种蚯蚓后(E,OE),土壤氮素矿化速率和累积矿化速率均显著高于(p<0.01)同期相应的无蚯蚓对照处理(S,O),并且在单接种蚯蚓(E)的条件下最高。在整个培养时期中,单接种蚯蚓处理(E)的土壤全氮含量较同期对照处理(S)显著提高了6.7%~32.7%,蚯蚓 秸秆处理(OE)的全氮含量除了在培养第6d外,其它培养时期均较同期单施秸秆处理(O)显著提高(p<0.05)了7.4%~25.4%。     

稻田土壤对铵的矿物固定对土壤保氮作用的贡献

为了定量评价土壤对铵的矿物固定作用在土壤对肥料氮的保持作用中的相对贡献,通过室内培养试验和分析测定,研究了湖南省几种主要母质发育的水稻土对添加铵的矿物固定作用及其对土壤保氮作用的贡献。结果表明:土壤对外源铵的矿物固定是土壤重要的保氮机制之一,但不同土壤对保氮作用的相对贡献大小不一,以河沙泥的固铵作用对土壤保氮作用的贡献最大,固铵量占总保氮量的51.5%,红黄泥最低,固铵量仅占总保氮量的17.1%,其余五种土壤的固铵作用对土壤保氮作用的贡献大小顺序依次是黄泥田(43.7%)、湖潮泥(35.5%)、紫泥田(35.4%)、灰泥田(25.0%)、麻沙泥(20.8%)。     

Heavy metals in Jamaican surface soils

A regional survey of Jamaican surface soils has been conducted in which more than 200 samples were collected at a sample density of 1 per 64 km² across the island and analysed for total concentrations of 31 elements by instrumental neutron activation analysis (INAA), energy dispersive X-ray fluorescence (EDXRF) analysis and atomic absorption spectrophotometry (AAS). The aim of the survey was to begin the construction of a high-precision geochemical database to provide information on elemental levels in soils for application to environmental studies, agriculture, and human and animal health. Results on the regional scale are presented for As, Cd, Cu, Hg and Pb. Although Jamaican surface soils are enriched in several heavy metals compared with world soil means and crustal abundances, lead is of particular importance at this stage because of its occurrence in residential areas. Except for Cu, the distribution maps of these elements are highly correlated with bauxite which in Jamaica is associated with white limestone geology and residualterra rossa soils.     

川西北高寒草甸两种蚯蚓的互作及其对土壤养分的影响

以川西北高寒草甸中普遍存在的两种蚯蚓(微小双胸蚓Bimastus parvus和威廉腔蚓Metaphire guillemi)为研究对象,采用野外微宇宙实验方法比较单独接种和混合接种时两种蚯蚓的数量、分布和繁殖状况,以及牛粪分解率和土壤养分含量的变化,探讨不同蚯蚓种群间的相互作用及其对土壤养分的影响.结果发现:1)两种蚯蚓混合接种加快了牛粪分解,增加了下层(10~20 cm)土壤可溶性氮含量,但对牛粪分解速率和土壤可溶性氮含量均不存在交互作用;2)在混合接种处理中,微小双胸蚓的死亡比率显著高于威廉腔蚓的死亡比率;3)两种蚯蚓混合接种处理时,威廉腔蚓的繁殖明显受到抑制,而微小双胸蚓的幼蚓数量有所增加.研究表明,威廉腔蚓和微小双胸蚓共存能够发生竞争性相互作用,加快地面上的牛粪分解,增加土壤可溶性氮含量,从而可能提高高寒草甸的初级生产力.     

己唑醇在土壤中的吸附-解吸特性

采用批量平衡法和气相色谱法研究了己唑醇在3种土壤中的吸附-解吸特性.结果表明,己唑醇在3种供试土壤中的等温吸附-解吸曲线能较好地符合Freundlich模型,其吸附常数(Kf)分别为0.791、2.274和43.800,显示3种土壤吸附行为存在较大差异.吸附率与土壤有机质含量(OM)、土壤阳离子交换量(CEC)和粘粒含量呈良好相关性.己唑醇在粘土和壤土中的等温吸附线属于L型等温吸附线,砂土中属S型.己唑醇在土壤中的吸附自由能为-5.186—-8.164 kJ.mol-1,表示吸附机理主要为物理吸附.     

Modeling salt transport in irrigated soils

This study evaluates the effects of the volume of leachate on the quality of the leachate. A numerical model of salt transport was used in the study. Field data were collected on 63 research plots located in the Grand Valley (Colorado, U.S.A.) and used to test and calibrate the model. The model was used in a series of hypothetical simulations designed to provide the required information.From the calibration of the moisture-flow model using infiltration data, soil water-content profiles, and soil water-storage change data, it was concluded that soil-water flow could be adequately modeled for the Grand Valley. The functional relations used for hydraulic conductivity and soil-water diffusivity and the method of averaging the values of the hydraulic parameters were developed during the course of the study. From comparisons of simulated and field data used in evaluating the chemistry model, it was concluded that total dissolved solids (TDS) concentrations were adequately modeled, but that individual ionic species concentrations were not. Comparison of calculated and measured data indicate that the CaSO₄CaCO₃Ca(HCO₃)₂ system is not properly modeled for the soil in the Grand Valley.Data for single growing season simulations using 7- and 14-day irrigation schedules and 2, 5, 20 and 40% leaching increments, coupled with data from a six-year simulation using a 14-day irrigation interval and 20% leaching increment, indicate that the salt concentration of the leachate at the bottom of the soil profile is independent of the volume of leachate.