广西典型高砷背景地区石漠化土壤中砷形态及相关因子研究

广西的喀斯特地貌分布广泛,部分石漠化地区的土壤砷污染问题比较突出。为深入了解广西重金属高背景地区石漠化土壤中砷的变化特征及其影响因素,采集广西环江县地质背景相似的不同石漠化程度(无石漠化、轻度石漠化、中度石漠化、重度石漠化)的表层土样,分析土壤样品中砷含量及形态,并采用多元线性回归模型分析石漠化土壤中砷形态的主要影响因子。结果表明,随着石漠化程度的加剧,表层土壤中砷含量呈现出逐渐增加的趋势,但是在重度石漠化土壤中砷含量有所下降。石漠化土壤样品中砷含量较高的区域分布在轻度和中度石漠化的中坡和下坡。石漠化土壤中砷形态主要以残渣态为主,其次是可氧化态和可还原态,最低的是水溶态;砷的水溶态、可氧化态、可还原态在土壤中的含量随着石漠化程度的加剧呈现出逐渐减少的趋势。多元回归分析表明阳离子交换量是影响水溶态砷和可氧化态砷的主要因子,p H值是影响弱酸提取态砷和可还原态砷的主要因子,呈极显著正相关(P0.01),总砷含量与残渣态砷呈显著正相关(P0.05)。     

厌氧微生物作用下土壤中砷的形态转化及其分配

厌氧微生物作用下土壤中砷的形态转化及分配比例对砷的环境行为与归趋具有重要影响。实验利用张士污灌区土壤负载低浓度砷,研究了厌氧微生物作用下砷的形态转化过程,并通过磷酸盐及盐酸提取土壤中的砷、铁和硫,探讨了砷在土壤中结合形态的变化及土壤矿物结构转化与砷环境行为的关联。实验结果表明,微生物作用下土壤负载的砷被迅速还原为As(III)并释放进入液相,培养24h后液相累积的As(T)量达到16.9μmol·L-1,其中As(III)占液相总砷含量的91%以上;48h后释放的砷被再次固持,液相残留的As(III)浓度仅为1.5μmol·L-1。尽管微生物还原作用造成土壤中铁氧化物的活化,但固相中磷酸盐提取态与盐酸提取态砷所占的比例分别从载砷量的45.3%和49.8%降低到22.0%与0.22%,而体系中硫酸盐还原产生的硫离子的量与砷的释放量保持负相关。可见微生物还原作用下砷发生了活化,释放和再固定的过程,土壤负载的砷从溶解态、吸附态及铁氧化物结合态逐渐被转化为更稳定的硫化物结合态。此研究对于预测土壤中砷的行为与归趋及污染土壤修复具有一定意义。     

水稻不同生育期土壤砷形态分布特征及其生物有效性研究

采用田间原位试验和Tessier连续提取方法,在水稻（Oryza sativa L.）不同生育期研究了重金属复合污染高、中、低3个水平下的土壤砷的形态分布特征及其生物有效性。结果表明：在水稻不同生育期中,土壤各种形态的砷质量分数均表现为高污染水平土壤〉中等污染水平土壤〉低污染水平土壤;土壤中砷在水稻整个生育期均以残留态为主,占90%以上,交换态砷所占比例最低,不到0.5%;不同形态砷之间大都显著正相关,但是两种有效性较高的砷形态（交换态和碳酸盐结合态）与有机态砷之间的相关性较差;土壤砷的生物有效性表现为高污染水平土壤〉中等污染水平土壤〉低污染水平土壤,且随着水稻生育期的延长,土壤砷的生物有效性逐渐升高。     

基于粒度的土壤团聚体中砷的形态分布特征

为明确土壤团聚体对砷分布和形态的影响,探讨污染农田中砷的可移动性及其环境风险,采集辽宁省某冶炼厂周边污染与非污染(对照)农田表土,采用湿筛法获得2 mm、2~0.25 mm、0.25~0.053 mm和0.053 mm 4个粒级的团聚体,分析明确了污染与对照土壤团聚体中全砷及污染土壤团聚体中各提取态砷的分布特征。结果表明,污染土壤0.25 mm粒级团聚体含量(78.49%)以及其中砷的分配量(80.83%)均显著高于对照土壤(64.33%、67.8%),其中0.25~0.053 mm粒级团聚体中砷的分配量最高(43.13%)。2 mm、0.25~0.053 mm以及0.053 mm粒级团聚体中各形态砷分布规律一致:残渣态(20.21~99.10 mg·kg~(-1))铁锰氧化物结合态(13.38~26.39 mg·kg~(-1))专性吸附态(5.19~8.86 mg·kg~(-1))非专性吸附态(1.13~2.94mg·kg~(-1))。而2~0.25 mm粒级团聚体中各形态砷为:残渣态(85.91 mg·kg~(-1))专性吸附态(28.48 mg·kg~(-1))铁锰氧化物结合态(25.63 mg·kg~(-1))非专性吸附态(6.00 mg·kg~(-1))。非专性吸附态和专性吸附态砷在0.25 mm粒级团聚体中的含量显著高于0.25 mm粒级团聚体。     

锑矿土壤中As和Sb的分布、形态及生物可利用性

采用微波消解-氢化物发生-原子荧光光谱法测定了晴隆锑矿区土壤中总砷和总锑,利用Tessier连续提取法分析土壤中不同形态砷和锑.结果表明,各采样点土壤As、Sb含量分别为17.98—127.85 mg·kg-1、171.93—601.59 mg·kg-1,远高于贵州省背景值;土壤中砷和锑的存在形态均以残渣态为主,其次是有机结合态、铁锰氧化物结合态和碳酸盐结合态,可交换态很少;土壤中生物可利用态锑占总和0.33%—1.72%,其含量为0.60—3.91 mg·kg-1,而土壤中生物可利用态砷占总和0.09%—0.57%,其含量为0.15—0.48 mg·kg-1.     

湘江排污口环境中砷的污染特征及潜在生态风险

对排污口砷的形态进行分析有助于从源头上找出水环境中砷污染的原因,为评估生态系统潜在风险及实施生态管理等提供科学依据。采用连续分级提取法研究了湘江下游某排污口表层沉积物(0~10 cm)中各形态砷的分布特征并对植物、水样中的砷进行了测定,其结果表明:排污口0~1 km的范围内沉积物中总砷的平均质量分数为1 373 mg?kg~(-1),各形态砷占比顺序为残渣态(72.74%~78.76%)晶形结合态(8.59%~10.77%)≈非晶形结合态(7.56%~13.78%)强交换态(2.53%~5.49%)弱交换态砷(0.18%~0.31%),残渣态砷为主要存在形式;排污口空心莲子草Alternanthera philoxeroides中砷质量分数为854.64mg?kg~(-1),其对水环境中的砷有着较强的富集作用(富集系数≈200);水生植物的生长可对沉积物中砷的迁移转化产生显著影响,水环境中的砷易被富集从而进入食物链中造成潜在的健康风险。因此,在治理水环境砷污染时应考虑砷不同形态之间的转化,从源头上减少砷的排放,降低其对环境所产生的生态风险。     

砷形态在湖水中垂直分布的研究

本文以天津水上公园湖泊作为研究现场，通过采样分析，研究了湖水中砷酸盐、亚砷酸盐、一甲基胂酸盐和二甲基胂酸盐的垂直分布及其影响因素。结果表明水上公园湖泊中砷酸盐是溶解态砷的主要存在形式，其垂直分布与悬浮物、叶绿素ａ、磷酸盐的浓度、水文等诸因素密切相关；一甲基胂酸盐含量保持相对稳定；光致转化是影响水中亚砷酸盐垂直分布差异的一个因素。     

寨上金矿矿区河流沉积物中砷的形态分析

在野外调查和样品采集的基础上,对寨上金矿矿区河流沉积物中砷的质量分数进行了测定,并采用Tessier连续提取法对砷在沉积物中的存在形态进行了提取分析。结果表明,砷在该区水系沉积物中质量分数较高（55.0~189.0μg.g-1）,说明金矿的开采已经对该区的环境造成了影响。运用Tessier连续提取法研究发现,沉积物样品中砷的提取率为89.87%~110.54%,样品沉积物中砷的形态分布基本一致,以残渣态为主,占其总量的85%以上,其他各形态相对含量较少,但相对活泼形态（水溶态、离子交换态和碳酸盐结合态）绝对质量分数较高（2.029~4.942μg.g-1）,说明该区水系沉积物中大部分砷在自然条件下相对比较稳定,小部分砷（1.10%~5.55%）易释放至环境中,但由于其绝对质量分数较高,将对环境产生较大危害。     

铜、砷在水稻－土壤体系中的迁移及其对水稻影响的研究

通过盆栽试验和现场布点试验，研究了铜、砷在水稻－土壤体系中迁移的规律。结果表明，该体系对铜、砷污染具有相当大的缓解作用；土壤中水溶性可交换态铜、砷含量很低；铜、砷主要累积在水稻根部；土壤中铜、砷相互有拮抗作用，确定土壤铜、砷临界值应考虑多因素综合作用。     

铜,砷在水稻—土壤体系中的迁移及其对水稻影响的研究

通过盆栽试验和现场布点试验，研究了铜、砷在水稻－土壤体系中迁移的规律。结果表明，该体系对铜、砷污染具有相当大的缓解作用；土壤中水溶性可产我换态铜、砷含量很低；铜、砷主要累积在水稻根部；土壤中铜、砷相互有拮抗作用，确定土壤铜、砷临临界值应考虑多因炭综合作用。     

天然浑浊水中共存无机阳离子的电动化学特征

引入流动电流这一重要电动化学参量，研究了在天然浑浊水中ＳＣ的基本模式，撮了ＳＣ与水中悬浮胶体颗凿表面电荷量及无机阳离子之间的理论关系，探讨了离子的浓度，性质，存在环境等对体系电动特性的影响，并对水中常见８种阳离子共存条件下的电动化学特性进行了实验分析，从而建立了无机阳离子对胶体的聚沉能力与电动响应特性之间的实际联系。     

芳香酸稀溶液的络合萃取研究

络合萃取法分离极性有机物稀溶液具有高效性和高选择性。本文利用三辛胺或磷酸三丁酯为络合剂,四氯化碳、三氯甲烷、正辛醇或煤油为稀释剂,实验测定了苯甲酸、邻硝基苯甲酸稀溶液的萃取相平衡分配系数,讨论了影响因素。     

Indicators of ecosystem function identify alternate states in the sagebrush steppe

Models of ecosystem change that incorporate nonlinear dynamics and thresholds, such as state-and-transition models (STMs), are increasingly popular tools for land management decision-making. However, few models are based on systematic collection and documentation of ecological data, and of these, most rely solely on structural indicators (species composition) to identify states and transitions. As STMs are adopted as an assessment framework throughout the United States, finding effective and efficient ways to create data-driven models that integrate ecosystem function and structure is vital. This study aims to (1) evaluate the utility of functional indicators (indicators of rangeland health, IRH) as proxies for more difficult ecosystem function measurements and (2) create a data-driven STM for the sagebrush steppe of Colorado, USA, that incorporates both ecosystem structure and function. We sampled soils, plant communities, and IRH at 41 plots with similar clayey soils but different site histories to identify potential states and infer the effects of management practices and disturbances on transitions. We found that many IRH were correlated with quantitative measures of functional indicators, suggesting that the IRH can be used to approximate ecosystem function. In addition to a reference state that functions as expected for this soil type, we identified four biotically and functionally distinct potential states, consistent with the theoretical concept of alternate states. Three potential states were related to management practices (chemical and mechanical shrub treatments and seeding history) while one was related only to ecosystem processes (erosion). IRH and potential states were also related to environmental variation (slope, soil texture), suggesting that there are environmental factors within areas with similar soils that affect ecosystem dynamics and should be noted within STMs. Our approach generated an objective, data-driven model of ecosystem dynamics for rangeland management. Our findings suggest that the IRH approximate ecosystem processes and can distinguish between alternate states and communities and identify transitions when building data-driven STMs. Functional indicators are a simple, efficient way to create data-driven models that are consistent with alternate state theory. Managers can use them to improve current model-building methods and thus apply state-and-transition models more broadly for land management decision-making.     

典型背景点降水化学组份的分析

全球背景降水划分为海洋型，内陆型和海洋与内陆相间型三种，以太平洋的Ａｍｓｔｅｒｄａｍ和大西洋的Ｓ；Ｇｅｏｒｇｅｓ为例，研究海洋型背景降水受海洋大气环流控制，化学组分来源于海洋气溶胶。分析了澳大利亚Ｋａｔｈｅｒｉｎｅ海洋与内陆相间型，背景降水化学组份来主要来源于海洋气溶胶和内陆大气污染传输两者的相关性。     

Predicting modes of spatial change from state-and-transition models

State-and-transition models (STMs) can represent many different types of landscape change, from simple gradient-driven transitions to complex, (pseudo-) random patterns. While previous applications of STMs have focused on individual states and transitions, this study addresses broader-scale modes of spatial change based on the entire network of states and transitions. STMs are treated as mathematical graphs, and several metrics from algebraic graph theory are applied—spectral radius, algebraic connectivity, and the S-metric. These indicate, respectively, the amplification of environmental change by state transitions, the relative rate of propagation of state changes through the landscape, and the degree of system structural constraints on the spatial propagation of state transitions. The analysis is illustrated by application to the Gualalupe/San Antonio River delta, Texas, with soil types as representations of system states. Concepts of change in deltaic environments are typically based on successional patterns in response to forcings such as sea level change or river inflows. However, results indicate more complex modes of change associated with amplification of changes in system states, relatively rapid spatial propagation of state transitions, and some structural constraints within the system. The implications are that complex, spatially variable state transitions are likely, constrained by local (within-delta) environmental gradients and initial conditions. As in most applications, the STM used in this study is a representation of observed state transitions. While the usual predictive application of STMs is identification of local state changes associated with, e.g., management strategies, the methods presented here show how STMs can be used at a broader scale to identify landscape scale modes of spatial change.     

化学农药污染土壤植物修复中的环境化学问题

报道了利用植草修复受DDT，BHC和Dicofol污染的研究，讨论了化学农药污染土壤植物修复中,农药在植物中富集与在土壤中降解以及结合残留等环境化学问题。研究表明，在植物修复的过程中，通过草对农药吸收的途径而去除土壤中污染物的作用所作的贡献很小，植草的作用可能是通过草的根部向土壤释放酶和某些分泌物，从而激发土壤中微生物的活性，并加速农药生物降解作用的结果。草在不同土壤中修复能力的差异，可能与不同土壤中所存土著微生物的差异以及其活性受酶和某些分泌物所激发差异的结果。选择能使根际区产生强烈的生物降解作用的草品种，是利用草作为化学农药污染土壤修复的关键。土壤与植株中农药结合残留的形成可能是土壤中污染物消除的又一个重要因素。     

The Clean Air Act Watch List and federal oversight of state enforcement efforts

For major federal environmental statutes in the United States, primary monitoring and enforcement responsibilities rest with most states. The Environmental Protection Agency (EPA) is charged with overseeing state efforts and has at its disposal formal tools to discipline lax states, tools which are rarely used. In this paper, we explore the extent to which the EPA's now-defunct Clean Air Act Watch List served as an informal tool for influencing the enforcement activities of state regulators. We estimate event studies designed around the primary listing criteria for the Watch List. Our empirical results are consistent with the average state regulator acting to reduce the chances of their facilities appearing on the Watch List. We also examine heterogeneity in the response to the Watch List between two states with high numbers of regulated facilities, Texas and California. We find a larger change in enforcement activity under the Watch List among state and local regulators in Texas compared to California.     

土壤中铍的存在形态及提取研究

本文对三种不同类型土壤中铍的存在形态及提取进行了研究,并做了原土铍和外加铍形态提取对照试验,选择了各形态合适的提取剂,建立了土壤铍形态连续提取方法,对提取机理和形态分布规律进行了探讨。此外,还对土壤提取的有效铍与盆栽植物吸收铍量的相关性进行了初步研究。     

添加不同化合态结合的铜离子对其在黄土中吸持及形态的影响

分别以CuSO4和Cu(NO3)2为吸持质，研究了添加不同化合态结合的铜离子在黄土中的等温吸持及形态分布规律。结果表明：黄土吸持铜离子以碳酸盐结合态为主。当铜离子初始浓度较低时，添加不同化合态结合的铜离子对其在黄土中的吸持及碳酸盐结合态没有明显影响；当铜离子初始浓度超过一定值时，添加不同化合态结合的铜离子对其在黄土中的吸持及碳酸盐结合态的影响随铜离子初始浓度的增加而明显增大。添加不同化合态结合的铜离子，其持有量和碳酸盐结合态含量均随土壤浓度的增大而减小。当铜离子初始浓度较低时，添加不同化合态结合的铜离子对其在黄土中的吸持量及碳酸盐结合态含量随土壤浓度的变化影响不大；当铜离子初始浓度超过一定值时，相同初始浓度条件下CuSO4较Cu(NO3)2会造成更大幅度的变化。     

典型化学污染物在环境中的变化及生态效应——国家自然科学基金“八·五”重大项目介绍

国家自然科学基金“八·五”重大项目——“典型化学污染物在环境中的变化及生态效应”已被批准立项,并将于1992—1995年内付诸实施。本项目研究内容涉及典型化学污染物在环境中迁移、转化及降解的化学过程;在多介质环境中的循环过程及模型;生态毒理学效应;对生态系统结构与功能的影响和预测;以及生态调控对策等五个课题。它是一项涉及环境化学、环境生态学和环境预防医学的多学科交叉的综合性研究项目。此项目科学意义重大,不仅是因为它与我国国民经济、生态环境和人体健康有着密切的关系,而且还因为它的研究将促进我国有关环境科学领域的基础和应用基础理论研究提高到一个新的水平。此外,它将为污染物的环境化学行为及生态效应的多学科,综合性研究积累方法学经验,从而为我国环保工作做出贡献。