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91.
Nonpoint-source pollution from agricultural activities is currently the leading cause of degradation of waterways in the United States. Applying best management practices to flood-irrigated mountain meadows may improve agricultural runoff and return flow water quality. Prior research has focused on fertilizer use for increased hay yields, while few studies have investigated the environmental implications of this practice. We examined the effects of fertilizer application timing on overland flow water quality from an irrigated mountain meadow near Gunnison, Colorado. Application of 40 kg phosphorus (P) and 19 kg nitrogen (N) ha(-1) using monoammonium phosphate (11-52-0, N-P-K) fertilizer to plots in the fall significantly reduced concentrations of reactive P and ammonium N in irrigation overland flow compared with early or late spring fertilization. Reactive P loading was 9 to almost 16 times greater when fertilizer was applied in the early or late spring, respectively, compared with in the fall. Ammonium N followed a similar trend with early spring loading more than 18 times greater and late spring loading more than 34 times greater than loads from fall-fertilized plots. Losses of 45% of the applied P and more than 17% of the N were measured in runoff when fertilizer was applied in the late spring. These results, coupled with those from previous studies, suggest that mountain meadow hay producers should apply fertilizer in the fall, especially P-based fertilizers, to improve hay yields, avoid economic losses from loss of applied fertilizers, and reduce the potential for impacts to water quality.  相似文献   
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93.
离子色谱/质谱联用分析水和食品中的高氯酸盐   总被引:2,自引:0,他引:2  
摘要用离子色谱/质谱联用(IC/MS)测定低ppb水平高氯酸根离子的方法.IC/MS是根据EPA方法314开发出来的,原方法用Ic分离电导检测,检测范围为1ppb.IC/MS在整个测定范围内,高氯酸盐回收率不受干扰基质的影响.在饮料和废水中0.5和1ppb添加水平的测定回收率为90%-105%,方法检测限(DML)低于100ppt.  相似文献   
94.
The continuing decline and loss of biodiversity has caused an increase in the use of interventionist conservation tools, such as translocation. However, many translocation attempts fail to establish viable populations, with poor release site selection often flagged as an inhibitor of success. We used species distribution models (SDMs) to predict the climate suitability of 102 release sites for amphibians, reptiles, and terrestrial insects and compared suitability predictions between successful and failed attempts. We then quantified the importance of climate suitability relative to 5 other variables frequently considered in the literature as important determinants of translocation success: number of release years, number of individuals released, life stage released, origin of the source population, and position of the release site relative to the species’ range. Probability of translocation success increased as predicted climate suitability increased and this effect was the strongest among the variables we considered, accounting for 48.3% of the variation in translocation outcome. These findings should encourage greater consideration of climate suitability when selecting release sites for conservation translocations and we advocate the use of SDMs as an effective way to do this.  相似文献   
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96.
Urban tinkering     
Cities are currently experiencing serious, multifaceted impacts from global environmental change, especially climate change, and the degree to which they will need to cope with and adapt to such challenges will continue to increase. A complex systems approach inspired by evolutionary theory can inform strategies for policies and interventions to deal with growing urban vulnerabilities. Such an approach would guide the design of new (and redesign of existing) urban structures, while promoting innovative integration of grey, green and blue infrastructure in service of environmental and health objectives. Moreover, it would contribute to more flexible, effective policies for urban management and the use of urban space. Four decades ago, in a seminal paper in Science, the French evolutionary biologist and philosopher Francois Jacob noted that evolution differs significantly in its characteristic modes of action from processes that are designed and engineered de novo (Jacob in Science 196(4295):1161–1166, 1977). He labeled the evolutionary process “tinkering”, recognizing its foundation in the modification and molding of existing traits and forms, with occasional dramatic shifts in function in the context of changing conditions. This contrasts greatly with conventional engineering and design approaches that apply tailor-made materials and tools to achieve well-defined functions that are specified a priori. We here propose that urban tinkering is the application of evolutionary thinking to urban design, engineering, ecological restoration, management and governance. We define urban tinkering as:
A mode of operation, encompassing policy, planning and management processes, that seeks to transform the use of existing and design of new urban systems in ways that diversify their functions, anticipate new uses and enhance adaptability, to better meet the social, economic and ecological needs of cities under conditions of deep uncertainty about the future.
This approach has the potential to substantially complement and augment conventional urban development, replacing predictability, linearity and monofunctional design with anticipation of uncertainty and non-linearity and design for multiple, potentially shifting functions. Urban tinkering can function by promoting a diversity of small-scale urban experiments that, in aggregate, lead to large-scale often playful innovative solutions to the problems of sustainable development. Moreover, the tinkering approach is naturally suited to exploring multi-functional uses and approaches (e.g., bricolage) for new and existing urban structures and policies through collaborative engagement and analysis. It is thus well worth exploring as a means of delivering co-benefits for environment and human health and wellbeing. Indeed, urban tinkering has close ties to systems approaches, which often are recognized as critical to sustainable development. We believe this concept can help forge much-closer, much-needed ties among engineers, architects, evolutionary ecologists, health specialists, and numerous other urban stakeholders in developing innovative, widely beneficial solutions for society and contribute to successful implementation of SDG11 and the New Urban Agenda.
  相似文献   
97.
Kriging is an accepted method of characterizing the groundwater elevation surface at sites where the water level data are available but where there may be insufficient additional data necessary for groundwater flow modeling. Groundwater surface interpolation via kriging is readily performed using commercial, state of the practice software, but some practitioners may not be able to justify such efforts because the process is not validated within studies documented in the peer‐reviewed literature. This paper describes the available kriging software and literature studies and then uses a case study to compare practical groundwater surface modeling to the studies available in the scientific literature. The literature review shows that the state of the practice as represented by the commercial software approach is consistent with the literature. Specifically, cokriging with groundwater elevation as the primary variable with trend removal and ground‐surface elevation as the secondary variable is an appropriate point of departure in practice. The literature review‐based summary of variogram model parameters (model type, nugget, sill, range, and trend model) was not useful as a quality‐control step to assess the reasonableness of variogram parameters identified by the standard practice of software‐assisted iteration when applied to the case‐study data set. The literature review indicated that groundwater elevation kriging has been performed using as few as 10 data points but a comparison of the case‐study simulated groundwater elevations and groundwater gradient magnitudes and directions indicated that the 30‐well threshold more commonly found in the literature was an appropriate minimum at the study site.  相似文献   
98.
We respond to the paper of Kruse-Plass et al. (Environ Sci Eur 29:12, 2017), published in this journal, regarding the risk to non-target lepidopteran larvae exposed to pollen from one or more of three Bt maize events (MON810, Bt11 and 1507). We emphasise that what is important for environmental risk assessment is not the number of pollen grains per se, but the degree of exposure of a NT lepidopteran larva to Bt protein contained in maize pollen. The main text of this response deals with general issues which Kruse-Plass et al. have failed to understand; more detailed refutations of each of their claims are given in Additional file 1. Valid environmental risk assessment requires direct measurement of pollen on leaves at varying distances outside a source field(s); such measurements reflect the potential exposure experienced by an individual larva on a host plant. There are no new data in the Kruse-Plass et al. paper, or indeed any data directly quantifying pollen on actual host-plant leaves outside a maize field; only data gathered within or at the edge of maize crops were reported. Values quoted by Kruse-Plass et al. for deposition on host plants outside the field were estimates only. We reiterate the severe methodological criticisms made by EFSA [Relevance of a new scientific publication (Hofmann et al. 2016) for previous environmental risk assessment conclusions and risk management recommendations on the cultivation of Bt-maize events MON810, Bt11 and 1507. EFSA Supp Publ; EN-1070, 2016], which render this estimation procedure unreliable. Furthermore, criticisms of EFSA (EFSA J 2015(13):4127, 2015) and of EFSA [Relevance of a new scientific publication (Hofmann et al. 2016) for previous environmental risk assessment conclusions and risk management recommendations on the cultivation of Bt-maize events MON810, Bt11 and 1507. EFSA Supp Publ; EN-1070, 2016] made by Kruse-Plass et al. are shown in Additional file 1 to be without foundation. We therefore consider that there is no valid evidence presented by Kruse-Plass et al. to justify their conclusions.  相似文献   
99.
The bee louse Braula coeca is a highly specialised flattened, wingless fly that spends its entire adult life on adult honeybees. It feeds by stealing food directly from bees during social feeding (trophallaxis). The Braula fly has a preference to infest the honeybee queen. The queen is the most attended individual in the colony but despite this the adult flies remain undetected by the workers. This is due to Braula possessing a cuticular hydrocarbon profile that mirrors that of their host honeybee colony, despite Diptera and Hymenoptera orders having separated over 290 million years ago. This chemical camouflage is most likely through odour acquisition from the honeybee host since even small colony-specific differences in the alkene isomer patterns present in the honeybees were also detected in the Braula’s profile. This finding further supports the idea that the honeybee recognition cues are contained within the alkene part of their hydrocarbon profile and Braula exploit this to remain undetected within an otherwise hostile colony.  相似文献   
100.
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