利用模拟和分析历史资料的方法根据《欧洲水框架指令》评价参考条件:以丹麦兰讷斯峡湾为例

<欧洲水框架指令>(WFD)要求确定所有地表水的参考条件,即原始条件.鉴于丹麦沿岸水域的目前状态不能被称为是原始的,因此,必须通过分析历史资料或利用模型来评价参考条件.以兰讷斯峡湾为例,本文的目的是①论证通过历史资料和模拟评价参考条件的可能性和限制因素;②论证生态条件是如何随着富营养化而改变的.来自兰讷斯峡湾的充分历史资料使我们能够评价与底栖大型植物和底栖动物有关的参考条件.具有不同复杂性的模型使我们能够评价营养物质、叶绿素α、透明度板深度以及大叶藻等的参考条件.我们断定,模型是评价参考条件的有益补充,尽管它们目前由于缺乏富营养化和物种组成之间的定量联系而受到限制.     

Earthwatch— Global environmental assessment

Progress of the United Nations Environment Program, Earthwatch, since its inception in 1972 is critically reviewed. The conclusion is reached that, while UNEP has provided support for several important programs in cooperation with United Nations specialized agencies, the new global assessment perspective envisioned at the 1972 Stockholm Conference on the Human Environment has not evolved. A framework is proposed calling for threshold criteria, statements of current conditions, predictions of trends to be watched, and alerts to warn of approaching environmental threats. A network of world, regional, and national assessment centers is recommended based on existing centers-of-excellence.Formerly a deputy associate administrator of the National Oceanic and Atmospheric Administration (NOAA). He was supported, in part, for this work under Department of State contract number 1751-000300, with project title: Global Environmental Monitoring System, 1979.National Marine Pollution Program Office, NOAA.The opinions and recommendations presented in this paper are those of the authors and do not necessarily represent the official policy or position of the National Oceanic and Atmospheric Administration, the Department of Commerce, or the U.S. Government.     

INSTITUTIONAL FACTORS AND THE TEXAS WATER PLAN1

Among the many problems associated with the implementation of the Texas Water Plan are the institutional arrangements necessary for interstate diversions, for management of transfer systems, for allocation and sale of water, and for developing repayment capabilities among water users.     

Effects of experimental acidification on mobilisation of metals from sediments of limed and non-limed lakes

In order to study the influence of pH on the mobilisation of metals from lake sediments, intact sediment cores with overlying water were sampled from one lime treated lake and one acidified lake. The overlying water of two cores from each lake was successively acidified to pH 4.2 over a period of 3 months. In the acid treated samples from the limed lake, the initial concentrations of Al, Cd, Mn, Pb and Zn in the overlying water were generally lower and the final concentrations were higher than in the acid treated samples from the acidified lake. The labile inorganic fraction of Al (Al(i)) was increasingly dominating as pH decreased. Redox potential and pH in the sediment indicated that the upper two centimetres were involved in the exchange reactions. The experiment showed that mobilisation of metals from sediments can occur and the results indicated that mobilisation could contribute to increased concentrations of metals in lake water during reacidification of formerly lime treated lakes.     

Eu3+ uptake by calcite: preliminary results from coprecipitation experiments and observations with surface-sensitive techniques

A lack of information in databases for contamination risk assessment about the transport behaviour of the trivalent f-orbital elements in groundwater systems where calcite is at equilibrium motivated this study of Eu(3+) uptake. The free drift technique was used to examine the effects of Eu(3+) concentration, presence of Na(+) or K(+) and temperature, as well as calcite nucleation and precipitation kinetics, on the partitioning of calcite. Changes in surface composition and morphology resulting from exposure of single crystals of Iceland spar to Eu(3+)-bearing solutions were observed with X-ray photoelectron spectroscopy (XPS) and atomic force microscopy (AFM). First results confirm that calcite has high affinity for Eu(3+). Rates of nucleation and precipitation strongly affect the extent of uptake but the presence of Na(+) and K(+) has no effect, suggesting formation of solid solution as CaCO(3)-EuOHCO(3). Surface-sensitive techniques prove that Eu(3+) is adsorbed to calcite even when the surface is dissolving and adsorption is not accompanied by precipitation of a separate Eu(3+)-solid phase. Adsorbed Eu modifies calcite's dissolution behaviour, roughening terraces and rounding step edges, and producing surface morphology where some surface sites appear blocked. Results imply that Eu(3+) concentrations in natural calcites are limited by Eu(3+) availability rather than by a lack of ability to fit into calcite's atomic structure. This behaviour can probably be expected for other trivalent rare Earth elements (REE), actinides and fission products whose behaviour is similar to that of Eu(3+). These elements are likely to be incorporated within the calcite bulk in systems where it is precipitating and the demonstrated strong partitioning ensures some uptake even where calcite is at or under saturation.     

Organizations in context: proposal for a new theoretical approach in prescriptive accident research

Lately, requests have been made to include the contexts of enterprises in models to prevent accidents at work. This paper presents different contextual theories in order to analyze whether this type of theory could be a way to elaborate our understanding of context. A differentiation is made between (a) theories of understanding relations between enterprises and regulatory agencies and (b) theories to perceive the relation between enterprise and the broader context. The last group of theories has its point of departure in an organizational understanding diverging from the classical, rational understanding of organizations and organizational processes. The conclusion is that contextual theories open for an elaborated understanding of the role of contextual relations in accident prevention, but also that an investigation of the potentials for making the theories action-orientated is needed.     

Regulation of aquaculture production

Environmental Economics and Policy Studies - In this paper, we investigate the economically optimal regulation of aquaculture production. The time between releasing and harvesting fish (rotation...     

How Should Death Be Taken into Account in Welfare Assessments?

That death is not a welfare issue appears to be a widespread view among animal welfare researchers. This paper demonstrates that this view is based on a mistaken assumption about harm, which is coupled to ‘welfare’ being conceived as ‘welfare at a time’. Assessments of welfare at a time ignore issues of longevity. In order to assess the welfare issue of death, it is necessary to structure welfare assessment as comparisons of possible lives of the animals. The paper also demonstrates that excluding the welfare issues of being deprived of life from the ethical assessment of killing distorts the ethical considerations.     

Determination of trace perchlorate in water: a simplified method for the identification of potential interferences

Background

Perchlorate contamination of water and food poses potential health risks to humans due to the possible interference of perchlorate with the iodide uptake into the thyroid gland. Perchlorate has been found in food and drinking, surface, or swimming pool waters in many countries, including the United States, Canada, France, Germany, and Switzerland, with ion chromatography (IC) being the preferred analytical method. The standardization of a robust ion chromatographic method is therefore of the high interest for public health and safety. This article summarizes the experiments and results obtained from analyzing untreated samples, considering the sample’s electrical conductance as guidance for direct sample injection as described in EPA 314.0.

Results

The suitability of ion chromatography with suppressed conductivity detection was tested for water samples in order to check the influence of matrix effects on the perchlorate signal of untreated samples. A sample injection volume of 750 μL was applied to the selected 2 mm?IC?column. The IC?determination of perchlorate at low µg/L levels is challenged by the presence of high loads of matrix ions (e.g., chloride, nitrate, carbonate, and sulfate at 100 mg/L and above). Perchlorate recovery is impaired with the increasing matrix ion concentrations, and its chromatographic peak is asymmetric particularly at low perchlorate concentrations. The identification of the individual maximum concentration of interfering anions like chloride, nitrate, and sulfate that influence perchlorate recovery helps to reduce the number of sample preparation steps or an obligatory measurement of the electrical conductivity of the sample. Within the scope of this study, samples containing less than 125 mg/L of either anion did not need sample preparation.

Conclusion

The identification of the maximum concentration of interfering anions like chloride, nitrate, and sulfate influencing perchlorate recovery provides a simplified alternative to the EPA 314.0 method. This approach reduces unnecessary sample preparation steps while allowing a reliable prognosis of possible interferences and maintaining result quality. This study was performed to support the development of a respective international standard, which is being established by the International Organization for Standardization (ISO). The results of the study are also intended to be used as guidance for interested laboratories to optimize the analytical workflow for trace perchlorate determination.

     

The puzzle of North America's Late Pleistocene megafaunal extinction patterns: Test of new explanation yields unexpected results

Although Late Pleistocene extinctions disproportionately affected larger mammalian species, numerous smaller species were also lost. To date, no satisfactory explanation has been presented to account for this pattern. Beginning with the assumption that human predation caused the extinctions, we offer and test the first such explanatory hypothesis, which is predicated on considering more realistic functional response forms (i.e., those that allow for predator interference or prey sharing). We then test the hypothesis via a one-predator, six-prey ecological model that maintains transparency, minimalism of design, and maximal constraint of parameters. Results indicate that altering assumptions about one cornerstone of ecological modeling (i.e., functional response) fails to produce qualitative differences in survival–extinction outcomes—even in conjunction with a wide range of capture efficiency permutations. This unexpected finding suggests that no reasonable form of predation alone is capable of producing the survival–extinction pattern observed. We conclude that the matter of causation and the conclusions of previous Late Pleistocene extinction models remain far less certain than many have assumed.