长江三角洲对流域输沙变化的响应:进展与问题

流域变化对河流三角洲的影响已成为全球性的问题。由于流域水库建设的影响,长江输沙率自1980年以来呈现明显下降趋势,引发了研究人员对长江三角洲地貌和沉积响应问题的关注。在地貌上,海图对比和海岸冲淤观测的证据显示,长江输沙率目前已经低于冲淤平衡的临界值,使三角洲进入了蚀退阶段。分析表明,根据水下三角洲部分范围的沉积速率与河流输沙率的关系进行计算,会过低估计临界输沙率。对于水下三角洲整体而言,应根据沉积物滞留指数来更准确地估算临界输沙率,而且需要区分2个"临界输沙率",一个是保持三角洲体积的临界值,另一个是保持三角洲陆上部分面积的临界值。在沉积响应上,来自长江水下三角洲沉积中心的柱状样显示出沉积速率自下而上减小的趋势,反映了流域输沙率变化的影响。今后,如将柱状样采集区域扩大到沉积中心之外的整个水下三角洲范围,则所获得的数据不仅有助于沉积速率响应特征的全面了解,而且还可应用于沉积物滞留指数特征和控制因素的分析以及河口区碳循环过程变化的研究。此外,在长江三角洲沉积记录的分析方面,为了更好地提取气候、环境演化信息,应充分考虑沉积记录形成后所经历的自身变化(如成岩作用变化、分解和衰变等)和相对于岸线迁移的空间位置变化。     

环境中高氯酸盐的来源、污染现状及其分析方法

高氯酸盐是一种持久性的无机污染物,它能够抑制碘的吸收并削弱甲状腺功能。随着高效灵敏的分离检测方法的发展,研究人员在多种环境介质中都检测到了高氯酸根,其环境污染问题引起了广泛的关注。最近的研究表明,环境中的高氯酸盐并非都来自于人为污染源及含有高氯酸盐的化肥,也有在大气中自然产生的,而且环境中存在大气来源的高氯酸根的背景值。在重点介绍了高氯酸盐的污染现状、分析方法以及自然条件下大气中产生高氯酸根的机理等方面的最新研究进展之后,提出今后应开展环境中高氯酸根背景值的调查研究。为此,应开发具有更低检出限的分析方法,并借助南极地区独特的地理优势开展南极雪冰中高氯酸盐的相关研究,从而获得不同历史时期环境中高氯酸根的背景值,并研究高氯酸根背景值的影响因素,为研究自然条件下大气中产生高氯酸根的机理提供基础数据。     

典型工业化国家SO2排放影响因素分析及其对中国的启示

通过美国100年来SO2排放趋势分析, 对比日本、英国的相关数据资料, 发现SO2的排放与能源消费、经济发展、环境政策以及环保技术进步密切相关: 经济结构的转变和能源结构的调整是SO2减排的关键因素, 环保政策和技术进步是SO2减排的主要驱动力。典型国家SO2排放强度曲线均呈倒“U”型, 符合环境库兹涅茨曲线。SO2排放的拐点美国在人均GDP15000美元, 日本和英国在人均GDP9000～10000美元; 三个国家人均SO2排放强度的拐点在人均GDP5000～7000美元, 目前中国已经越过人均SO2排放的顶点。在此基础上本文提出了中国进一步减排SO2的建议。     

Greening the Dam: The case of the San Roque Multi-purpose Project in the Philippines

This article aims to illustrate the extent and ways in which a traditional development aid project became the focus of a ‘greening’ process in the 1990s (and beyond). The article examines the San Roque Multi-purpose Project in the Philippines - a major Japanese bilateral international cooperation project - from a political ecology perspective. The analysis highlights how a complex story of contemporary aid dynamics in the bilateral Japan-Philippines relationship influenced this ‘greening’ process. The article interrogates critically and empirically the stated greening of a proto-type development aid project. This specific example of the practices of the Japanese aid industry is set within the context of the wider political economy of both donor and recipient elite interests.     

Monitoring the remediation of a near shore waste disposal site in Antarctica using the amphipod Paramoera walkeri and diffusive gradients in thin films (DGTs)

The water quality of a marine embayment (Brown Bay) was monitored during the remediation of an abandoned waste disposal site at Casey Station, East Antarctica, using a combination of biomonitoring and chemical methods. The Antarctic amphipod Paramoera walkeri, in field mesocosms suspended in the water column, was deployed adjacent to the site and at two reference sites for periods of 14 days, repeated three times during the remediation period (December to February). Diffusive gradients in thin film (DGT) samplers were deployed for the same periods to provide estimates of dissolved metals. No difference in mortality of amphipods was observed between Brown Bay and reference sites. There were significant differences, however, in accumulated metal concentrations between amphipods from Brown Bay and reference sites, with greater concentrations of antimony, copper, cadmium, lead, iron and tin at Brown Bay. The melt water/runoff treatment strategy employed for the remediation was successful in preventing acute toxic effects, but water quality was reduced at Brown Bay, where increased metal bioavailability may have been high enough to induce chronic effects in some biota. DGT samplers were less sensitive than amphipods in detecting differences in metal concentrations between sites, indicating that metals bound to suspended particulates were a potentially significant source of contamination.     

Biomarkers in environmental and human health risk assessment

Marine pollution is a major threat to human and environmental health. Given the complexity of function of marine and coastal ecosystems, it is unlikely that a balanced view of the nature and extent of risk will easily be achieved if human and environmental risk assessments continue to be conducted in isolation. Here, the integration of assessment protocols is advocated as a holistic means of improving risk management. Biomarkers can provide the common conceptual framework and measurable endpoints necessary for successful integration. Examples are given of the ways in which suites of biomarkers encompassing molecular change, cellular pathology and physiological impairment can be developed and adapted for human and ecological scenarios. By placing a greater emphasis on the health status of impacted biota, it is more likely that risk assessment will develop the efficiency, reliability and predictive power to adapt to the unforeseen environmental threats that are an inevitable consequence of human development and global change.     

Assessing neuroprotective P-glycoprotein activity at the blood-brain barrier in killifish (Fundulus heteroclitus) using behavioural profiles

The neuroprotective role of P-glycoprotein, a multixenobiotic resistance transporter (ABCB1/MDR1), in the blood-brain barrier in fish was examined using behavioural toxicological assays. P-glycoprotein acts as cellular efflux pump to prevent substrates from accumulating in the brain, including environmental contaminants such as ivermectin, a common aquaculture pesticide and mammalian anti-parasitic drug. The behavioural toxicological assays were developed to determine the neuropathological effect of ivermectin in killifish (Fundulus heteroclitus). P-glycoprotein function and thus blood-brain barrier integrity can be compromised by chemosensitizers that inhibit transport activity. Fish treated with ivermectin and the P-glycoprotein inhibitor cyclosporin A were significantly more sensitive and succumbed more rapidly to tilting, lethargy, slowing of pectoral-fin movement and loss of haptic-reactivity compared to fish treated with ivermectin-only. P-glycoprotein inhibition is associated with significantly earlier onset and increased mortality in ivermectin-exposed fish. Our results suggest that P-glycoprotein confers resistance against ivermectin-induced behavioural neuropathology and mortality in fish. This assay provides us with a non-invasive tool to study P-glycoprotein function in the blood-brain barrier and evaluate the behavioural effects of potential environmental neurotoxins.     

Delineation of hydrologically similar units in a watershed based on fuzzy classification of soil hydraulic properties

Evaluation of flow and transport processes in a watershed‐scale requires that the watershed be divided into homogenous spatial units referred to as hydrologically similar units (HSUs). Although a few discretization schemes are already in use, a universally acceptable method of obtaining HSUs is yet to emerge. In this study, we developed a fuzzy inference system (FIS) to classify the saturated hydraulic conductivity (K_s) and two water‐retention parameters α and n into fuzzy logic‐based soil hydrologic classes (FSHCs). Analysis of these classes showed that soil properties within an FSHC have less variability and those between two FSHCs have large variability. This result suggested that soils belonging to a specific FSHC may be more similar than those across different FSHCs and may be grouped together to represent an HSU. Soils within a specific hydrologic class were aggregated to delineate HSUs within the watershed. For the Dengei Pahad micro‐watershed (DPW), this approach showed five distinct regions representing a discretized zone having similar soil hydraulic properties. Application of this approach on a larger international database of soil hydraulic properties revealed that the developed hydrologic classes are quite comparable across different databases. The delineated HSUs based on these FSHCs were also better than the soil series map of the watershed in maintaining the soil heterogeneity of the watershed. Moreover, this new discretization scheme using the SWAT modelling environment showed better performance than the soil series‐based discretization approach. Copyright © 2010 John Wiley & Sons, Ltd.     

Application of a stochastic model to estimate children’s short-term residential exposure to lead

The Cumulative and Aggregate Simulation of Exposure (CASE) framework is an innovative simulation tool for exploring non-dietary exposures to environmental contaminants. Built upon the Dermal Exposure Reduction Model (DERM) and established methods for collecting detailed human activity patterns, the CASE framework improves upon its predecessor. Although prompted in part by the Food Quality Protection Act of 1996 and the need to assess aggregate exposure to pesticides, the framework was designed to be flexible enough to assess exposure to other contaminants. This paper examines features of the CASE framework in an illustrative application estimating children’s dermal and non-dietary ingestion exposure to lead in the residential environment. Concentration values in various media are taken from a nationwide study and exposure factors are obtained from the literature. Activity pattern input includes sequential micro-level activities collected for 20 children (ages 1 through 6). Modeled results are explored via classification trees and sensitivity analysis. Results of each exposure route are also compared to independent data. Median dermal exposure estimates were 589 and 558 μg/m³ for the right and left hands, respectively, with the resulting output most sensitive to exposure factor terms. The simulation estimated a median non-dietary ingestion rate of 9.5 μg of lead per day with estimates most sensitive to the surface area of mouthed objects.