大气酸化和实验酸化的北方湖泊中石生藻类群落的复原能力

藻类群落对恢复中酸化湖泊的环境变化具有高度响应性.本文比较了北方湖泊的石生藻类群落从大气酸化(安大略省基拉尼公园)和实验酸化(南302湖,安大略省实验湖泊区)的化学恢复,以评价严重酸化的时空尺度对分类学复原能力(即恢复速率)的影响.复原能力以经过典型对应分析(CCA)湖泊在pH恢复过程中的排序空间上的位移来表示.基拉尼湖泊的复原能力相对而言几乎可以忽略,说明南303号湖8年时间酸化实验对生物恢复的影响要弱于几十年来的大气酸化作用.溶解性有机碳、溶解性无机碳以及钙的增长很好地解释了恢复过程中的酸化湖泊的石生物种丰度的时间变化.南302湖中观察到了相反的分类学复原能力和抗性的轨迹(抗性指扰动后自原来状态的偏离),显示在恢复和酸化过程中影响石生物种的生态因子随相应的pH值不同而不同.本文的发现揭示了在对严重酸化湖泊的生态系统恢复建立模型时,一定要考虑扰动的时空尺度以及引起恢复和酸化轨迹差异的生物滞后响应.     

Adaptive management of marine mega-fauna in a changing climate

Management of marine mega-fauna in a changing climate is constrained by a series of uncertainties, often related to climate change projections, ecological responses, and the effectiveness of strategies in alleviating climate change impacts. Uncertainties can be reduced over time through adaptive management. Adaptive management is a framework for resource conservation that promotes iterative learning-based decision making. To successfully implement the adaptive management cycle, different steps (planning, designing, learning and adjusting) need to be systematically implemented to inform earlier steps in an iterative way. Despite the critical role that adaptive management is likely to play in addressing the impacts of climate change on marine mega-fauna few managers have successfully implemented an adaptive management approach. We discuss the approaches necessary to implement each step of an adaptive management cycle to manage marine mega-fauna in a changing climate, highlighting the steps that require further attention to fully implement the process. Examples of sharks and rays (Selachimorpha and Batoidea) on the Great Barrier Reef and little penguins, Eudyptula minor, in south-eastern Australia are used as case studies. We found that successful implementation of the full adaptive management cycle to marine mega-fauna needs managers and researchers to: (1) obtain a better understanding of the capacity of species to adapt to climate change to inform the planning step; (2) identify strategies to directly address impacts in the marine environment to inform the designing step; and (3) develop systematic evaluation and monitoring programs to inform the learning step. Further, legislation needs to flexible to allow for management to respond.     

Achieving attainable outcomes from good science in an untidy world: case studies in land and air pollution

While scientific understanding of environmental issues develops through careful observation, experiment and modelling, the application of such advances in the day to day world is much less clean and tidy. Merseyside in northwest England has an industrial heritage from the earliest days of the industrial revolution. Indeed, the chemical industry was borne here. Land contamination issues are rife, as are problems with air quality. Through the examination of one case study for each topic, the practicalities of applied science are explored. An integrated, multidisciplinary response to pollution needs more than a scientific risk assessment. The needs of the various groups (from public to government) involved in the situations must be considered, as well as wider, relevant contexts (from history to European legislation), before a truly integrated response can be generated. However, no such situation exists in isolation and the introduction of environmental investigations and the exploration of suitable, integrated responses will alter the situation in unexpected ways, which must be considered carefully and incorporated in a rolling fashion to enable solutions to continue to be applicable and relevant to the problem being faced. This integrated approach has been tested over many years in Merseyside and found to be a robust approach to ever-changing problems that are well described by the management term, “wicked problems”.     

Evaluation of disinfection techniques in the treatment of advanced primary treated wastewater for Ciudad Juárez, México.

The purpose of this study was to develop and evaluate the effectiveness of alternative disinfection techniques at the bench-scale level using wastewater from Ciudad Juarez, Mexico, as model feed. This paper presents findings on the effectiveness of UV radiation, peracetic acid (PAA), chlorine dioxide (ClO2), and hypochlorous acid (HOCl) as disinfectants for advanced primary treatment (APT) plant effluent. Wastewater samples for bench-scale testing were collected from an agua negra ("black water") ditch that is part of the combined sewer system in Ciudad Juarez. Bench-scale simulations of the APT process used in Ciudad Juarez were run using a jar test apparatus and aluminum sulfate [Al2(SO4)3] as the coagulant. Jar test effluent from the bench system was used for disinfection testing. The Mexican discharge quality standard for total coliforms is 10 000/100 mL. Ultraviolet radiation met this standard at a dose of 47.5 mW-s/cm2. Ultraviolet disinfection proved reliable and effective despite the presence of suspended solids, and UV dose effectiveness expressed as a total coliforms survival ratio was best explained by a linear regression model. The ClO2 dose ranged from 10 to 20 mg/L and was only effective under ambient temperature conditions found during the winter months; PAA disinfection never met Mexican standards. Chlorine disinfection was effective at a dose range of 8 to 10 mg/L on samples collected at low temperature conditions. Since the completion of this research, Ciudad Juarez has discontinued the use of chlorine disinfection because of its high cost and ineffectiveness.     

Accumulation of Cu and Zn from antifouling paint particles by the marine macroalga,Ulva lactuca

The marine macroalga, Ulva lactuca, has been exposed to different concentrations of antifouling paint particles (4–200 mg L^?1) in the presence of a fixed quantity of clean estuarine sediment and its photosynthetic response and accumulation of Cu and Zn monitored over a period of 2 days. An immediate (<2 h) toxic effect was elicited under all experimental conditions that was quantitatively related to the concentration of contaminated particles present. Likewise, the rate of leaching of both Cu and Zn was correlated with the concentration of paint particles added. Copper accumulation by the alga increased linearly with aqueous Cu concentration, largely through adsorption to the cell surface, but significant accumulation of Zn was not observed. Thus, in coastal environments where boat maintenance is practiced, discarded antifouling paint particles are an important source of Cu, but not Zn, to U. lactuca.     

A national critical loads framework for atmospheric deposition effects assessment: IV. Model selection,applications, and critical loads mapping

The critical loads approach is emerging as an attractive means for evaluating the effects of atmospheric deposition on sensitive terrestrial and aquatic ecosystems. Various approaches are available for modeling ecosystem responses to deposition and for estimating critical load values. These approaches include empirical and statistical relationships, steady-state and simple process models, and integrated-effects models. For any given ecosystem, the most technically sophisticated approach will not necessarily be the most appropriate for all applications; identification of the most useful approach depends upon the degree of accuracy needed and upon data and computational requirements, biogeochemical processes being modeled, approaches used for representing model results on regional bases, and desired degree of spatial and temporal resolution. Different approaches are characterized by different levels of uncertainty. If the limitations of individual approaches are known, the user can determine whether an approach provides a reasonable basis for decision making. Several options, including point maps, grid maps, and ecoregional maps, are available for presenting model results in a regional context. These are discussed using hypothetical examples for choosing populations and damage limits. The research described in this article has been funded by the US Environmental Protection Agency. This document has been prepared at the EPA Environmental Research Laboratory in Corvallis, Oregon, through contract #68-C8-0006 with ManTech Environmental Technology, Inc., and Interagency Agreement #1824-B014-A7 with the U.S. Department of Energy and at Oak Ridge National Laboratory managed by Martin Marietta Energy Systems, Inc., under Contract DE-AC05-84OR21400 with the US Department of Energy. Environmental Sciences Division Publication No. 3904. It has been subjected to the agency’s peer and administrative review and approved for publication. Mention of trade names or commercial products does not constitute endorsement or recommendation for use.     

A national critical loads framework for atmospheric deposition effects assessment: II. Defining assessment end points,indicators, and functional subregions

The United States Environmental Protection Agency, with support from the US Department of Energy and the National Oceanographic and Atmospheric Administration, has been evaluating the feasibility of an effects-based (critical loads) approach to atmospheric pollutant regulation and abatement. The rationale used to develop three of the six steps in a flexible assessment framework (Strickland and others, 1992) is presented along with a discussion of a variety of implementation approaches and their ramifications. The rationale proposes that it is necessary to provide an explicit statement of the condition of the resource that is considered valuable (assessment end point) because: (1) individual ecosystem components may be more or less sensitive to deposition, (2) it is necessary to select indicators of ecosystem condition that can be objectively measured and that reflect changes in the quality of the assessment end point, and (3) acceptable status (i.e., value of indicator and quality of assessment end point at critical load) must be defined. The rationale also stresses the importance of defining the assessment regions and subregions to improve the analysis and understanding of the indicator response to deposition. Subregional definition can be based on a variety of criteria, including informed judgment or quantitative procedures. It also depends on the geographic scale at which exposure and effects models are accurate and on data availability, resolution, and quality. The research described in this article has been funded by the US Environmental Protection Agency. This document has been prepared at the EPA Environmental Research Laboratory in Corvallis, Oregon, through contract #68-C8-0006 with ManTech Environmental Technology, Inc., and Interagency Agreement #1824-B014-A7 with the US Department of Energy and at Oak Ridge National Laboratory managed by Martin Marietta Energy Systems, Inc., under Contract DE-AC05-84OR21400 with the US Department of Energy. Environmental Sciences Division Publication No. 3903. It has been subjected to the agency’s peer and administrative review and approved for publication. Mention of trade names or commercial products does not constitute endorsement or recommendation for use.