Arsenic and Heavy Metal Pollution of Soil,Water and Sediments in a Semi-Arid Climate Mining Area in Mexico

The environmental impact of arsenic and heavy metals on a 105 km² area of the historical and recent mining site of Villa de la Paz-Matehuala, San Luis Potosí (Mexico) was evaluated. Results of soil samples reported concentrations between 19–17 384 mg kg^-1 As, 15–7200 mg kg^-1 Cu, 31–3450 mg kg^-1 Pb and 26–6270 mg kg^-1 Zn, meanwhile, the concentrations in dry stream sediment samples were found to vary between 29–28 600 mg kg^-1 As, 50–2160 mg kg^-1 Pb, 71–2190 mg kg^-1 Cu, and 98–5940 mg kg^-1 Zn. The maximum arsenic concentration in pluvial water storage ponds (265 μg L^-1), near the main potential sources of pollution, exceed by 5 times the Mexican drinking water quality guideline (50 μg L^-1). The arsenic concentrations in water storage ponds and stream sediments decrease as distance from the potential sources increase. A special case is the `Cerrito Blanco' area located 5 km east of Matehuala, where the highest arsenic concentration in water was found (>5900 μg L^-1), exceeding by 100 times the established guideline, thus representing a severe health risk. The results suggest that arsenic and heavy metal dispersion from their pollution sources (historical and active tailings impoundments, waste rock dumps and historical slag piles), is mainly associated in this site with: (1) fluvial transportation of mine waste through streams that cross the area in W–E direction; and (2) aeolian transportation of mineral particles in SW–NE direction. Finally, control measures for pollution routes and remediation measures of the site are proposed.     

Trace Metal Bioaccumulation and Plant Growth on Dredged River Sediments and Biosolids Mixtures

Dredged river sediments and biosolids used as amendments for agricultural purposes can provide a suitable plant growth medium, a topsoil substitute. Nevertheless, trace metal bioaccumulation and risk of plant toxicity remains a concern. We conducted a greenhouse experiment to evaluate the plant growth and trace metal bioaccumulation on sediments and biosolid mixtures. These included dredged sediment from the Peoria Lakes portion of the Illinois River and class A biosolids from the Metropolitan Water Reclamation District of Greater Chicago. Six different mixtures were produced in addition to a standard greenhouse mix serving as a control. Barley (Hordeum vulgare) and snap bean (Phaseolus vulgaris) were grown on the mixtures in the greenhouse. Plants grew in all treatments, except for snap beans that were stunted likely by high salt content in unleached biosolid mixtures. The highest overall biomass production for barley was obtained in the treatment composed of 50% sediment and 50% biosolids. For snap bean, the highest biomass productions were obtained in treatments composed of ≤50% biosolids in the mixture. Trace metals in plant tissue were within ranges considered normal, except for Mo in snap bean, which was at a level considered excessive. However, addition of biosolids to sediments decreased Mo plant uptake. Based on our results, sediments mixed with biosolids make a fertile topsoil and have no inherent chemical or physical properties that would preclude its use as a plant growth medium. Adding sediments to unleached fresh biosolids improved plant growth and diminished trace metal uptake. The suggested optimal ratio of sediments to biosolids would be 80:20 to 70:30 by volume in most situations.     

The Influence of Sediment Sources and Hydrologic Events on the Nutrient and Metal Content of Fine-Grained Sediments (Attert River Basin, Luxembourg)

Nutrient (C, N and P) and metal (Cr, Cu, Ni, Pb and Zn) content and dynamics of suspended and channel bed sediments were analysed within the rural Attert River basin (Luxembourg). This basin is representative of the main physiographic characteristics of the country, where there is currently little information available on the composition and dynamics of fluvial sediment. Stream bed fine-grained sediment samples (n?=?139) collected during low flow conditions and time-integrated suspended sediment samples (n?=?183) collected during storm runoff events (October 2005 to April 2008) in seven nested basins ranging from 0.45 to 247?km² were analysed. Nutrient and metal spatial patterns, temporal trends and the relationship between their content and storm runoff characteristics (e.g. maximum discharge and sediment concentration) were assessed. Results showed a high spatial and temporal variability, mainly associated with basin characteristics and local inputs. Higher values of total C were measured in the highly forested basins located in the northern part of the Attert River basin, whereas the highest values of total P were mainly associated with material coming from grassland and with the inflow of wastewater treatment plants (i.e. higher values of total P were measured in the southern part of the basin). The abundance of metals, not only in suspended but also in channel bed sediments, was generally as follows: Zn > Cr > Ni > Pb > Cu. Both nutrient and metal concentrations were at a maximum at the beginning of the wet season, after having been accumulated during the summer. These values tended to decrease during autumn and winter due to sediment mobilisation, and a higher flow capacity to transport coarser particle fractions from the sources. In general, concentrations of nutrients and metals on suspended sediment were negatively correlated with antecedent precipitation, total precipitation, total specific discharge and maximum discharge, which has been previously associated to a ??dilution?? effect during storm runoff events. Results show that both sediment sources and hydrologic events play an important role on the spatial and temporal variability of sediment-associated nutrient and metal contents.     

潮河流域不同水土保持措施配置方案对年径流量的影响

结合潮河流域2005年的水土流失状况,基于水土保持的生态、经济、社会三大目标以及保证粮食生产区域自给和增加植被覆盖率两项原则,建立了粮食保障方案、生态优先方案、综合水保方案3种水土保持措施配置方案.基于不同降水水平年潮河流域水平梯田和林地的减水定额,模拟分析了不同水土保持措施配置方案下流域年径流量的变化.结果表明,若流域水土流失面积全部造林,丰、平、枯水平年减水量分别占流域多年平均径流量的8.27%,8.28%和11.13%,对流域年径流量的影响程度较大;若按综合水保方案,丰、平、枯水平年减水量分别占流域多年平均径流量的11.42%,8.38%和13.21%,对流域年径流量的影响程度最大;粮食保障方案下,丰、平、枯水平年减水量分别占流域多年平均径流量的7.59%,6.03%及9.11%,对流域年径流量的影响程度较小.     

The Effect of River Liming on the Trace Metal Budgets of a Down Stream Lake

Sediment cores from two lakes, connected by a limed river, were analyzed for organic matter, calcium (Ca), iron (Fe), manganese (Mn), zinc (Zn), copper (Cu), lead (Pb), cadmium (Cd), and ion exchange capacity. The distribution of trace metals in the pristine upper lake is governed primarily by changes in the long distance atmospheric transported pollutants. In the lake down stream of the liming station the distribution of trace metals in sediments deposited before liming started (1985) is similar to that in the pristine lake. Liming of the connecting river raises the pH value by about 1.8 units from 5.1 enhancing the accumulation rate of trace metals in the downstream lake. Iron enriched acid insoluble particles are likely to be important carriers of trace metals. The liming agent itself is the most important source for Pb, while increased accumulation of Zn and Cd is caused primarily by enhanced scavenging of dissolved metals. For Cu the two sources are of about equal importance.     

退耕还林还草工程实施对洛河流域土壤侵蚀的影响

退耕还林还草工程是中国实施的重要生态环境建设与保护工程,对区域植被覆盖及土壤侵蚀产生重要影响。以洛河流域（陕北黄土高原部分）为研究对象,利用流域通用土壤侵蚀方程（RUSLE）,结合流域降雨、土壤类型、DEM、植被覆盖等数据,定量分析了2000—2010年退耕还林还草工程实施对流域土壤侵蚀的影响。结果表明:（1）洛河流域2000—2010年耕地面积减少,林地、草地面积增加,土地利用变化主要发生在2000—2005年;（2）洛河流域2000—2010年土地利用变化导致植被NDVI平均值增大,耕地变化区域植被NDVI值增加幅度高于耕地未变化区域,表明耕地变化区域植被NDVI增加对耕地区域总体植被NDVI值增加贡献较大;（3）降雨侵蚀力和退耕还林还草工程实施对土壤侵蚀具有明显的影响。受降雨侵蚀力增大影响,2000—2010年洛河流域土壤侵蚀呈增加趋势;不考虑降雨侵蚀力变化情况下,洛河流域土壤侵蚀呈减少趋势,反映出退耕还林还草工程实施对土壤侵蚀的减缓作用。     

Mapping the Distribution of the Bioaccessible Fraction of Trace Metals in the Sediments of an Urban Stream,Park River Watershed,Connecticut

The Park River watershed (PRW), a sub-basin of the Lower Connecticut River watershed, has experienced increased urbanization over the last century as the city of Hartford and its surrounding towns have grown and developed. We present watershed-wide and outflow scale maps of the trace metals Cd, Cu, Zn, and Pb to determine patterns of contamination in fine (<63 μm) stream sediment. Results are compared to established sediment quality guidelines (SQG) and probable effect concentrations (PEC) for each metal. Throughout the watershed, higher concentrations of trace metals are observed in the more urbanized south branch of the PRW. In this sub-basin, there are more industries that use, and waste, metals in their manufacturing processes that contribute to acutely high concentrations of metals in the fine bedload sediments. Impervious surfaces are examined as well in the context of the entire watershed. While an increase in metals can be attributed to an increase in impervious surfaces, these increases do not generally exceed SQGs and PECs. Two focused mapping studies were conducted at the storm water outflow of the West Hartford Landfill and the Trout Brook Sanitary Sewer Overflow (SSO). The purpose of these studies was to analyze the local effects of natural stream features such as channel bar deposits next to the outfalls. We determined that the sediment directly below the two outfalls often exceeded the PEC, while the accumulated sediment around the channel bar deposits was not contaminated beyond background stream levels. We believe mapping at both the small (watershed) and large (outfall) scale can be helpful in future urban studies to determine the extent of trace metal sediment contamination in both channelized and natural sections and may provide a useful method for sediment mitigation endeavors.

     

The Effect of Former Mining Activities on Contamination Dynamics in Sediments,Surface Water and Vegetation in El Avenque Stream,SE Spain

This work aims to identify and characterize heavy metal contamination in a fluvial system from Cartagena–La Unión mining district (SE Spain). In order to assess the dynamics of transport and the accumulation of heavy metals, sediments, surface water and vegetation, samples along “El Avenque” stream were collected. The former direct dumps of wastes and the presence of tailing ponds adjacent to the watercourse have contributed to the total contamination of the stream. Total Cd (103 mg kg⁻¹), Cu (259 mg kg⁻¹), Pb (26,786 mg kg⁻¹) and Zn (9,312 mg kg⁻¹) in sediments were above the limits of European legislation, being highest where tailing ponds are located. Bioavailable metals were high (3.55 mg Cd kg⁻¹, 6.45 mg Cu kg⁻¹, 4,200 mg Pb kg⁻¹ and 343 mg Zn kg⁻¹) and followed the same trend than total contents. Metals in water were higher in sampling points close to ponds, exceeding World Health Organization guidelines for water quality. There is a direct effect of solubilisation of sediment metals in water with high contents of SO₄²⁻, product of the oxidation of original sulphides. The mobility of metals varied significantly with shifts in pH. Downstream, available and soluble metals concentrations decreased mainly due to precipitation by increments in pH. As a general pattern, no metal was bioaccumulated by any tested plant. Thus, native vegetation has adopted physiological mechanisms not to accumulate metals. This information allows the understanding of the effect of mining activities on stream contamination, enforcing the immediate intervention to reduce risks related to metals’ mobility.     

Spatial and Temporal Variability of Total Non-Residual Heavy Metals Content in Stream Sediments from the Suquia River System,Cordoba, Argentina

The Suquía is a semiarid (rainfall, 700-900 mm y-1), medium-size (7700 km2) riversystem located in central Argentina. Its mountainous upper catchment includes pristine areas aswell as a variety of human settlements and a reservoir lake. A large city (Córdoba, ca. 1.3million inhabitants) and a terminal hypersaline lake are included in the middle and lower basin.Total non-residual (TNR) heavy metals (Pb, Cu, Ni, Zn, Mn, and Fe) have been determined inriver bed sediments in two seasons (spring and autumn), seeking to establish the factors whichcontrol the temporal and spatial variability. The major findings were: a) concentrations of TNRmetals were, in general, higher during springtime than during autumn, particularly downstreamfrom the city of Córdoba; b) organic matter played a significant role as a controlling factorwherever it defined reducing conditions, lowering the concentrations of Mn and Fe hydrousoxides; c) a higher organic load (e.g., downstream the city) and more pronounced reducingconditions could be the causes for the increased Fe concentration, probably precipitated assulfides; d) organic matter exhibited a closer correlation with some TNR metals in autumn,probably caused by a larger capacity for complexation in the biologically-processed organicdebris; and, e) the existence of pristine areas in the drainage basin allowed for the calculation ofenrichment factors (EF) which show the significance of several environmental impacts in theSuquía system.     

初始含水率及容重影响下红壤水分入渗规律

运用室内模拟土柱试验,研究了初始含水率为7%,11%和15%这3个梯度及容重为1.2,1.3,1.4,1.5g/cm~3这4个梯度对均质红壤水分入渗规律的影响;根据Kostiakov模型和Philip模型对入渗过程进行拟合分析,得出入渗模型参数。试验结果表明:均质红壤水分入渗,入渗率、湿润锋运移速率与时间呈幂函数递减关系,Philip入渗模型较适用;随着时间的推进,土壤逐渐达到饱和,入渗率、湿润锋运移速率的变化也越来越小;入渗率与初始含水率成反比关系,初始含水率越高,入渗率越低;湿润锋运移速率随初始含水率增加而增大;土壤容重越大,入渗率越低,湿润锋运移越慢。     

玛纳斯河流域土壤盐渍化影响因素研究

为了探讨区域盐渍化过程和分布特征,本文通过野外调查和室内分析,研究了新疆玛纳斯河流域海拔高度、地貌类型、地下水埋深、土地利用类型和不同种植年限对土壤盐分含量变化的影响。结果表明:玛纳斯河流域土壤盐分含量随海拔高度的变化呈现先降低后升高再降低的趋势,高盐分含量主要集中在海拔350~400 m,海拔高度与土壤盐分含量之间没有很好的变化趋势;土壤盐分含量在不同地貌类型的分布状况为:冲积洪积扇缘带冲积平原中部冲积平原下部冲积洪积扇中部干三角洲地区,冲积洪积扇缘带与冲积平原中部的土壤剖面盐分有表聚和底聚现象,冲积平原下部土壤剖面中间层盐分含量较高;地下水埋深对土壤盐分含量变化影响明显,随着地下水埋深的变浅,土壤盐分含量显著增加;不同土地利用方式下,土壤含盐量具有显著性差异,荒地土壤盐分含量最高,表层和底层盐分高于中间层,耕地0~100 cm土层盐分含量均较低;随着滴灌年限的增加,0~100 cm土层盐分含量均呈现降低趋势,滴灌1年与3年表层盐分含量差异不显著,其他土层差异显著,滴灌8年与10年的各层土壤盐分含量差异均不显著。综上,玛纳斯河流域土壤盐分含量受地貌类型、地下水状况、土地利用类型和滴灌年限因素影响显著,盐分在土壤剖面上也表现出不同的分布特征。     

Effects of Restored Stream Buffers on Water Quality in Non-tidal Streams in the Choptank River Basin

Restoration of riparian buffers is an important component of nutrient reduction strategies in the Chesapeake Bay watershed. In 1998, Maryland adopted a Conservation Reserve Enhancement Program (CREP), which provides financial incentives to take agricultural land out of production to plant streamside vegetation. Between 1998 and 2005, 1–30% of streamside vegetation (average?=?11%), was restored to forest or managed grass in 15 agriculturally dominated sub-basins in the Choptank River basin, a tributary of Chesapeake Bay. Pre-existing forested buffers represented 10–48% of the streamside (average?=?33%), for a total of 12–61% buffered streamsides (average?=?44%). Using multi-year water quality data collected before and after CREP implementation (1986, 2003–2006), we were unable to detect significant effects of CREP on baseflow nutrient concentrations based on the area of restored buffer, the percentage of restored streamside, or the percentage of total riparian buffer in the sub-basins (p?>?0.05). Although CREP increased the average buffered streamside from 33% in the 1990s to 44% by 2005, N and P concentrations have not changed or have increased in some streams over the last 20 years. Reductions may not have occurred for the following reasons: (1) buffer age, width, and connectivity (gaps) between buffers are also important to nutrient reductions; (2) agricultural nutrient inputs may have increased during this period; and (3) riparian buffer restoration was not extensive enough by 2005 to have measurable affects on the stream water quality in these sub-basins. Significant effects of CREP may yet be resolved as the current CREP buffers mature; however, water quality data through 2006 in the Choptank basin do not yet show any significant effects.     

祁连山大野口流域降水-土壤水-河川来水相关性分析

[目的]对祁连山大野口流域降水、土壤水和河川来水的相互关系进行分析,旨在为掌握流域水文过程及河川径流形成机理提供理论支持。[方法]运用祁连山大野口流域18a人工和2a自动监测的38万多个数据,采用特征参数算法、相关和多元回归等方法进行分析。[结果](1)降水量、空气湿度和河川径流18a平均为374.06mm,60.91%,166.73mm。降水的44.57%最后形成了河川径流。降水和河川径流上升率均为18mm/10a,空气湿度上升率约为1.2%/10a。(2)降水、空气湿度、土壤水、河川来水在一年中的变化步调基本一致。(3)在森林高度范围内,距地面越高,空气湿度越大,受降水的影响越小;在0—80cm深度范围内,土壤越深,降水对土壤水分的影响越小。(4)降水、空气湿度、土壤水、河川来水的相互关系较紧密,建立的回归模型可预测降水、土壤水、河川来水量变差的95.2%,88.8%,97.6%,准确率可达93.4%,84.6%,96.7%。[结论]降水、土壤水、河川来水的分配比例可量化和可调控流域水资源需水量方面的分配比例;将人工观测和自动监测数据同化分析,解决了流域生态水文过程研究中的数据短缺问题。     

中国黑河流域与澳大利亚墨累-达令河流域水管理对比研究

水管理问题是中国西北内陆河流域社会经济发展及生态环境建设的关键问题之一,而有效的水管理,是中国各大河流尤其是西北内陆流域面临的重要问题。在对中国西北黑河流域与澳大利亚东部墨累-达令河流域概况分析的基础上,探讨了两流域水管理的相关问题,在借鉴墨累-达令河流域管理的成功经验基础上,提出了优化黑河流域水管理的对策:(1)优化用水结构,提高经济效益;(2)重视统一管理,实现水资源优化配置;(3)强化组织管理,制定流域管理法;(4)鼓励公众参与,进一步深化水权制度改革。     

九龙江流域的水土流失与治理

九龙江流域(漳州段)水土流失面积956.1km2,占土地总面积的14.13%。水土流失导致土壤退化、旱涝灾害频繁、河床抬高、水利设施被毁等严重问题,日益引起九龙江流域群众及各级政府的重视。根据漳州段水土流失现状,规划"十五"期间治理水土流失面积200km2,2006—2015年治理水土流失面积300km2,2016—2030年治理水土流失面积400km2。治理上,要推广成功的小流域综合治理模式,特别重视坡地果园的水土流失治理。     

黄河流域及西北内陆河地区大型开发建设项目水土保持工作

黄河上中游管理局于2005年组织对黄河流域及西北内陆河地区水利部批复水土保持方案的113个大型开发建设项目水土保持工作进行了督查,从督查情况看,项目实施水土保持方案及防治水土流失工作取得了一定的进展,但仍存在投入不足、防治措施实施及后续设计不到位等问题。针对这些问题,提出了加大宣传力度,提高认识;制定制度,规范管理;加强水土保持方案后续设计及变更申报管理等对策建议。     

Studies of Soils, Soil Water and Stream Water at a Small Catchment near Guiyang, China

Acid deposition is considered to be a major environmental problem in China, but information about effects on soils and waters is scarce. To contribute to increased knowledge about the problem a small catchment (about 7 ha) in the outskirts of Guiyang, the provincial capital of Guizhou in south-western China, was instrumented for collection of precipitation, throughfall, soil water and stream water. In addition soil samples have been collected and analyzed for key properties. Median pH in the precipitation is 4.40 (quartiles: 4.19 and 4.77) and the median sulfate concentration 228 µeq/L (quartiles: 147 and 334 µeq/L). The dry deposition of both SO₂ and alkaline dust is considerable. The sum of wet deposition of sulfate and dry deposition of SO₂ has been estimated to about 8.5 gSm^-2yr^-1. The total S-deposition may be somewhat higher due to dry deposition of sulfate and occult deposition. In soil water, SO₄ ^2- is the major anion, generally ranging from 300 to 2500 µeq/L in the different plots. Calcium is an important cation, but there is also a considerable contribution of aluminum from the soil. In some of the plots the concentrations of inorganic monomeric aluminum (Ali) are typically between 200 and 400 µm. Potential harmful levels of aluminum and/or high Ali/(Ca²⁺ + Mg²⁺) molar ratios occur in the catchment, but damages to vegetation have not yet been reported. In most cases exchangeable aluminum accounts for between 75 and 95% of the total effective cation exchange capacity (CEC_E) in the mineral soils. The aluminum chemistry cannot easily be explained by conventional models as the Gaines-Thomas ion-exchange equation or equilibrium with an Al(OH)₃ mineral phase. The stream water is generally less acidic and has considerably lower concentrations of aluminum than the soil water, even though quite acid events have been observed (pH < 4.4). The median pH values are 4.9 and 5.0 in the two first order streams and 6.3 in the dam at the lower boarder of the catchment.     

制度优化——生态认证与汉江上游水土保持实践

针对西北地区脆弱的生态环境,为实现该地区经济发展与生态建设的良性互动,就其生态经济发展模式的制度优化结构、生态经济制度创新层次结构和生态经济管理创新的层次结构进行了初步探讨和研究。以汉江上游——西北地区秦巴山地与汉水谷地泥石流治理区为例,详细分析了该区生态认证的内容:一是植被的生产过程能否涵养水源、保持水土;二是植被的生产过程能否降低或避免崩塌、滑坡、泥石流等地质灾害的发生。     

长江流域水土保持与可持续发展探讨

长江是闻名世界的“黄金水道”，在地域和经济上占有重要地位，是我国国计民生的大动脉；在西部大开发中起着纽带的重要作用，水土流失是长江流域最严重的生态环境问题之一，分析其水土流失的历史演变，现状、特征及成因，提出水土保持与可持续发展的对策及原则。