Application of semi-quantitative electrofishing to juvenile salmonid stock surveys

A semi-quantitative electrofishing technique is described, which has applications for assessing distribution and densities of 0+ salmonids in streams. Linear regressions of logarithmically-transformed data satisfactorily described the relationship between numbers of 0+ Atlantic salmon ( Salmo salar L.) and 0+ brown trout ( Salmo trutta L.) captured in a standard 5 min fishing and quantitative population estimates obtained using a commonly used method. Applications of the semi-quantitative technique to management are discussed and a categorization system proposed.     

The impact of hybrids between genetically modified crop plants and their related species: biological models and theoretical perspectives

Forces affecting the rate of spread and increase of hybrids between genetically modified crop plants and their related species remain qualitatively similar, irrespective of whether genetic modification was achieved using traditional methods, those of biotechnology or as a result of the natural evolutionary process. However, the precise magnitude of the forces and, consequently, the likely environmental impact of such hybrids, may depend strongly on the nature of the gene or genes introduced into the native species. While many classes of transgenes are similar to those manipulated by conventional breeding techniques or evolution, biotechnology offers the potential to introduce genes into crops which are novel both from the point of view of function and origin. The qualitative similarity between transgenes and the products of conventional or evolutionary modification suggests that a historical view of the environmental impact of hybrids between traditionally produced crops or exotic species and their relatives would be of use in estimating the probable fate of hybrids containing transgenes in the environment. However, with certain classes of transgenes for which there are no existing analogues, there will need to be greater care in assessing the possible risks associated with release into the environment.     

Assessing the risks of transgene escape through time and crop-wild hybrid persistence

Transgenes introduced into crops can escape in time, as well as space, via the seed bank. For annual plants, especially ruderals, seed bank behaviour may be the most important factor determining population persistence. Crop seeds may exhibit some dormancy and germination cueing in the soil but are expected to be less able to persist than their wild relatives, which often have considerable dormancy and longevity, as well as effective germination cueing responses. Crop-wild hybrids may have seed bank characteristics more suited to persistence, and maternal effects may favour persistence of hybrids having wild plants for their female parent. Escape of transgenes via crop-wild hybrids presents unique concerns not present for crops. Hybrids can undergo natural selection and may back-cross with wild plants. We suggest methods that can be used in conjunction with evaluation of the relative fitness of crop-wild hybrids that will determine the likelihood of back-crossing. Accurate assessment of escape in time and transgene persistence via crop-wild hybrids requires proper plant materials. We emphasize the use of null segregants as controls for transgenic crops and for generating crop-wild hybrid controls for transgenic hybrids. Since good empirical and theoretical understanding of how individual genes influence the fate of plants in different environments is lacking, evaluation of escape in time and the persistence of transgenes via crop-wild hybrids should be on a case-by-case basis.     

Opportunities for gene transfer from transgenic oilseed rape (Brassica napus) to related species

Before novel transgenic plant genotypes are grown outside containment facilities and evaluated under field conditions, it is necessary to complete a risk assessment to consider the possible consequences of that release. An important aspect of risk assessment is to consider the likelihood and consequences of the transgene being transferred by cross-pollination to related species, including other crops, weeds and ruderal populations. The purpose of this report is to review the literature to assess the ease with whichBrassica napus can hybridize with related species. The evidence for hybridization is considered at three levels: a) by open pollination, b) by hand pollination and c) by the use ofin vitro ovule and embryo rescue techniques; and also examines the fertility and vigour of the F₁, F₂ and backcross generations. Four species are reported to hybridize withB. napus by open pollination:B. rapa andB. juncea using fully fertile parents; andB. adpressa andR. raphanistrum using a male-sterileB. napus parent. Seventeen species are reported to form hybrids (including the four species above) withB. napus when pollination is carried out manually. At least 12 of these species were unable to form F₂ progeny, and eight were unable to produce progeny when the F₁ was backcrossed to one of the parental species. Many factors will influence the success of hybridization under field conditions, including: distance between the parents, synchrony of flowering, method of pollen spread, specific parental genotypes used, direction of the cross and the environmental conditions. Even where there is a possibility of hybridization betweenB. napus and a related species growing in the vicinity of a release, poor vigour and high sterility in the hybrids will generally mean that hybrids and their progeny will not survive in either an agricultural or natural habitat.     

Perspectives on environmental risk assessment

Risk is by no means a simple concept. Natural variability and definitional problems with the concept of probability complicate the measurement and use of risk as an analytical tool. Variability requires that risk assessment methods separate natural from total risk when attempting to estimate anthropogenic risk. Failure to do so results in the over estimation of anthropogenic risk and the eventual loss of credibility for risk assessment methodologies. The common frequentist approach to probability is not consistent with anything but a modelling approach to risk assessment. When combined with its ability to account for natural variability, incorporate laboratory-assay data and offer complete statistical and experimental control, modelling is a promising approach to risk assessment. Modelling, however, is not without its drawbacks. Initialization bias can result in the over, or under, estimation of both natural and anthropogenic risk. Furthermore, model estimates are time dependent. The convergence of natural and anthropogenic risk poses problems for modelling-based risk assessment and requires clear statements as to the importance of the time dimension in risk assessment. When combined, the drawbacks to modelling-based risk assessment argue that risk should never be stated as a scalar quantity. Instead, modelling-based risk assessment should provide estimates of the complete range of risk measures (total, natural, and anthropogenic) as well as indications of convergence time. Only then can the modelling-based approach be viewed as the most appropriate means of carrying out scientifically credible risk assessment.     

Evaluation of health risks from a buried mass of diesel fuel before and after bioremediation

Plans are being formulated for in situ bioremediation of a subsurface plume of diesel fuel No. 2 that resulted from an accidental fuel release. Raoult's law and the aqueous solubilities of the toxic components were used to estimate organic contaminant concentrations in leachate from the untreated fuel mass. Carcinogenic risks and noncarcinogenic hazard indices were calculated for undiluted leachate. An 80% decrease in hydrocarbon mass and increases in the average molecular weights of the component fractions were assumed to result from the treatment. Sample calculations are provided to show how to evaluate results of analyses for petroleum hydrocarbons after bioremediation.     

黄桃罐头产品质量Fuzzy综合鉴评

本文根据FuzzZ数学理论,运用多级模型的综合评判法,对国内20种黄桃罐头产品质量进行了优劣鉴评。并将其划分为一、二、三、四4个等级。从而为罐头产品质量鉴评,准确地汰劣遴优提供新方法。     

呼和浩特地区蔬菜污染现状综合评价

呼和浩特地区蔬菜污染现状综合评价杨在中（内蒙古大学,呼和浩特０１００２１）黄雅琴（内蒙古环境监测中心站,呼和浩特０１００１０）ＣｏｍｐｒｅｈｅｎｓｉｖｅａｓｓｅｓｓｍｅｎｔｏｎｐｏｌｌｕｔｉｏｎｓｔａｔｕｓｏｆｖｅｇｅｔａｂｌｅｓｉｎＨｕｈｅｈｏｔ．...     

转基因微生物生态学及大田释放风险评价研究

向环境中释放转基因微生物可能会带来一系列的安全问题．在大面积释放之前必须对转基因微生物在环境中发生基因转移的潜力、存活能力、扩散能力及对生态系统的潜在影响等进行生态学研究和风险评价,同时还要探索有效的检测方法和风险评价策略．该研究有助于分子生态学的发展和生物技术的安全应用,具有重要的理论和实践意义．     

Combining industrial ecology tools to assess potential greenhouse gas reductions of a circular economy: Method development and application to Switzerland

Industrial ecology (IE) methodologies, such as input/output or material flow analysis and life cycle assessment (LCA), are often used for the environmental evaluation of circular economy strategies. Up to now, an approach that utilizes these methods in a systematic, integrated framework for a holistic assessment of a geographic region's sustainable circular economy potential has been lacking. The approach developed in this study (IE4CE approach) combines IE methodologies to determine the environmental impact mitigation potential of circular economy strategies for a defined geographic region. The approach foresees five steps. First, input/output analysis helps identify sectors with high environmental impacts. Second, a refined analysis is conducted using material flow and LCA. In step 3, circular strategies are used for scenario design and evaluated in step 4. In step 5, the assessment results are compiled and compared across sectors. The approach was applied to a case study of Switzerland, analyzing 8 sectors and more than 30 scenarios in depth. Carbon capture and storage (CCS) from waste incineration, biogas and cement production, food waste prevention in households, hospitality and production, and the increased recycling of plastics had the highest mitigation potential. Most of the scenarios do not influence each other. One exception is the CCS scenarios: waste avoidance scenarios decrease the reduction potential of CCS. A combination of scenarios from different sectors, including their impact on the CCS scenario potential, led to an environmental impact mitigation potential of 11.9 Mt CO₂-eq for 2050, which equals 14% of Switzerland's current consumption-based impacts.