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31.
Residential runoff as a source of pyrethroid pesticides to urban creeks   总被引:1,自引:0,他引:1  
Pyrethroid pesticides occur in urban creek sediments at concentrations acutely toxic to sensitive aquatic life. To better understand the source of these residues, runoff from residential neighborhoods around Sacramento, California was monitored over the course of a year. Pyrethroids were present in every sample. Bifenthrin, found at up to 73 ng/L in the water and 1211 ng/g on suspended sediment, was the pyrethroid of greatest toxicological concern, with cypermethrin and cyfluthrin of secondary concern. The bifenthrin could have originated either from use by consumers or professional pest controllers, though the seasonal pattern of discharge from the drain was more consistent with professional use as the dominant source. Stormwater runoff was more important than dry season irrigation runoff in transporting pyrethroids to urban creeks. A single intense storm was capable of discharging as much bifenthrin to an urban creek in 3 h as that discharged over 6 months of irrigation runoff.  相似文献   
32.
Phosphorus (P) is an essential macronutrient in agriculture; however, lack of reporting makes its supply chain a black box. By using literature synthesis on the P challenge, we identify four areas where the reporting process is problematic: P reserves and resources; P losses along the supply chain; P externalities; and access to data. We find that in these areas, the reporting system is inconsistent, inaccurate, incomplete, fragmented and non-transparent. We use systems analysis to discuss implications of reporting on the sustainability of the P supply chain. We find that reporting is essential for the achievement of global P governance and the human right to adequate food. It can also inform decision makers and other impacted stakeholders on policies on agriculture, food security, pollution and international conflict. An improved P reporting process also allows a better evaluation of global sustainability commitments such as the United Nations Sustainable Development Goals.  相似文献   
33.
Protected areas (PAs) are a frequently used conservation strategy, yet their socioeconomic impacts on local communities remain contentious. A shift toward increased participation by local communities in PA governance seeks to deliver benefits for human well‐being and biodiversity. Although participation is considered critical to the success of PAs, few researchers have investigated individuals’ decisions to participate and what this means for how local people experience the costs and benefits of conservation. We explored who participates in PA governance associations and why; the perceived benefits and costs to participation; and how costs and benefits are distributed within and between communities. Methods included 3 focus groups, 37 interviews, and 217 questionnaire surveys conducted in 3 communities and other stakeholders (e.g., employees of a nongovernmental organization and government officials) in PA governance in Madagascar. Our study design was grounded in the theory of planned behavior (TPB), the most commonly applied behavior model in social psychology. Participation in PA governance was limited by miscommunication and lack of knowledge about who could get involved and how. Respondents perceived limited benefits and high costs and uneven distribution of these within and between communities. Men, poorer households, and people in remote villages reported the highest costs. Our findings illustrate challenges related to comanagement of PAs: understanding the heterogeneous nature of communities; ensuring all households are represented in governance participation; understanding differences in the meaning of forest protection; and targeting interventions to reach households most in need to avoid elite capture.  相似文献   
34.
假如地球上没有人类据《新科学家》报道,毋庸置疑,人类是地球有史以来最具统治力的生物。仅仅数千年的时间,城市、农田和牧场就侵占了地球陆地超过1/3的面积。据估计,人类现在霸占了地球40%的生产力。人类的连番冲击让地球变得满目疮痍:草原变为耕地,森林夷为平地,地下蓄水层干枯;而核能废料、化学污染、入侵物种、生物灭绝及气候变暖都是人类活动造成的直接恶果。如果可能的话,与人类分享地球的其它生物会毫不犹豫地把我们“踢出”地球。现在,假设它们如愿以偿,地球上65亿人明天一夜之间从地球上消失,被送到遥远的星系接受再教育,那么,地球将会发生怎样的变化?  相似文献   
35.
Climate Change Projections for the United States Midwest   总被引:1,自引:0,他引:1  
Environmental and societal factors such asair quality, water quality andavailability, land use changes andexpanding urbanization are alreadyaffecting human health and welfare,agriculture, and natural ecosystems in theMidwestern United States. Over thiscentury, these existing stresses willlikely be exacerbated by climate changesresulting from human activities. It isessential that policy decisions aimed atpreserving the well-being of a region beinformed by a good understanding of theregion's climate, how climate might change,and the uncertainties inherent in futureprojections. Recent updates in climatemodeling expertise and an expanded view ofpossible non-intervention emissionscenarios have narrowed the range of changethat can be expected over the Midwestthroughout the next century in some ways,while broadening it in others. In contrastto previous studies, which generallyconsider a mid-range scenario for futureemissions, this study presents the range ofchange that would result from low to highscenarios for climate change. In this waywe account for uncertainties inanthropogenic forcing on climate change inthe region and quantify the potentialeffects of human actions on future climate.This analysis also combines the latestclimate model projections with historicalrecords of observed climate over the pastcentury, effectively placing potentialchanges in extreme event frequencies suchas heavy rainfall events and temperaturethreshold exceedances within the context ofobserved variability over the past century.The purpose of this study is to provide anupdated picture of the potential impacts ofclimate change on the Midwest to inform theimpact assessment and policy developmentcommunity. From the magnitude of thechanges projected by this study, it isclear that these must be included in futurepolicy decisions in order to ensure thesuccessful adaptation and survival ofexisting human and natural systems in theMidwest.  相似文献   
36.
Gammarus oceanicus Segerstråle, 1947 and Echinogammarus marinus (Leach, 1815) were sampled during the breeding season from Oslofjord in 1984, and their lipid composition examined in relation to reproductive condition. In G. oceanicus, female lipid content increased as the ovary matured. Both the amount of lipid stored and the rate of accumulation were greater in spring than in winter. Spring eggs contained 12.4 g lipid, of which 63% was triacylglycerol and 27% phospholipid. Both fractions decreased steadily during embryonic development. Winter eggs contained 19.2g lipid, of which 52% was triacylglycerol and 43% phospholipid. During the early stages of embryonic development the amount of phospholipid decreased sharply, whereas that of triacylglycerol increased, suggesting that some of the fatty acid released from phospholipid was sequestered temporarily as triacylglycerol. When newly spawned, both winter and spring eggs were richer in monoenoic fatty acids than adult amphipods and these acids were the major fuel consumed during development. 6 fatty acids were utilised more slowly than 3 acids, and egg carotenoid pigment content remained constant. Female E. marinus increased in lipid content as the ovary matured. Spring eggs contained 14.7 g lipid when newly spawned and this increased to 16.6 g during the early stages of development. This increase was entirely triacylglycerol, which declined in later stages; the source of the extra lipid was unclear. Eggs contained very little phospholipid or sterol, and both of these components remained at a steady low level during development. E. marinus eggs were not significantly rich in thonoenoic acids compared with adults, and saturated, monoenoic and polyenoic acids were utilised about equally during development. Both adults and eggs were rich in 20.46, which was utilised at a slower rate than the 3 polyunsaturated acids during embryonic development; again, egg carotenoid pigment content remained constant. In both species there was a decrease in the size of the egg (and as a result, of the newly hatched juvenile), but an increase in total reproductive output (i.e., the total weight of the egg clutch) per female as the breeding season proceeded. The reproductive output of an individual female is probably related to food availability during the period of ovarian maturation, whereas the size of an individual egg is dictated largely by feeding conditions for the juveniles once they are independent of the female. The different patterns of lipid utilisation during development found in this study emphasize the flexibility of response in the reproductive biology of gammarid amphipods. It is not yet possible, however, to relate the differing patterns in a simple way either to egg size or total female reproductive output. Two outstanding problems are the source of extra triacylglycerol during the early stages of development of E. marinus and the metabolic cost of brooding eggs.  相似文献   
37.
A similar, sexual dimorphism in Copepodite Stage V was observed in winter generations of Calanus finmarchicus (Gunnerus) and C. helgolandicus (Claus), co-existing in the Firth of Clyde, Scotland. In both species, the frequency distribution of prosome length in the Copepodite V population was bimodal. Among individual Stage V copepodites kept in the laboratory, those of the larger form alone produced adult males. Indications of morphological distinctions between the forms other than in size, however, were absent. Differences in least-squares regressions of individual cephalosome on metasome lengths, previously attributed to a distinction in prosome shape by Grigg et al. (1985), reflected size alone. These two measurements also were greater in the “large” form, but this independently of each other. Variations in their relative contributions to the prosome length distinguished individuals, and were continuous between the forms. Present and previously published observations on members of the family Calanidae have been compared. The presence, or not, of a sexual distinction in prosome length in the Stage V copepodite is variable among calanids, within and between species. A possible association with the extent of seasonal variations in size and life-cycle characteristics is suggested.  相似文献   
38.
We have determined the congener compositions of nine commercial Aroclor products of polychlorinated biphenyls (PCBs) to the sub-part-per-million level using high-resolution gas chromatography combined with high-resolution mass spectrometry according to US Environmental Protection Agency (EPA) Method 1668A. These Aroclor composition data should allow improved characterization and risk assessment of PCB contamination at hazardous waste sites, particularly for dioxin-like PCB congeners. By combining the data on the concentrations of each dioxin-like congener with its World Health Organization toxicity equivalency factor, we have established dioxin toxic equivalent concentrations for each pure Aroclor product.  相似文献   
39.
Summary By removing older males from their breeding territories, we tested the hypothesis that age-related dominance behavior influenced the pattern of habitat selection by breeding American redstarts Setophaga ruticilla (Aves: Parulinae). Fifteen older male redstarts removed in five experimental replicates during three breeding seasons were replaced by ten yearling and five older males; no redstart males of either age colonized the control sites during the same time periods, although two yearlings disappeared. Significantly more yearling males (67%, n=9) colonized the vacated areas than were present in the redstart population at large (26.8%, n=209). We reject the alternative hypothesis that yearling male redstarts occupy different habitats from older males because of age-related (innate) habitat preferences. Redstarts that colonized the territories made vacant by our removals (i.e., floaters) were a behaviorally heterogeneous group of animals. The presence of both yearling and older male floaters indicates that suitable habitat is limiting for this species and that intraspecific competitive interactions are important in habitat distribution, and potentially in population regulation.  相似文献   
40.
The prenatal diagnosis of achondrogenesis in association with cystic hygroma is described. Ultrasound findings of severe short-limbed dwarfism, decreased vertebral ossification, and normal ossification of the calvarium were all consistent with achondrogenesis type II. Although the unusual finding of associated cystic hygroma raised the suspicion of a concurrent chromosome abnormality, the karyotype of both fetal lymphocytes and fetal fibroblasts was normal. Autopsy confirmed dilated lymphatic channels in the basal endothelial layer of the skin, cystic hygroma, and coarctation of the aorta. Although previously unreported, we suggest that the features of this case of achondrogenesis indicate an association with lymphatic stasis and jugular lymphatic obstruction sequence in this syndrome.  相似文献   
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