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171.
Gerecke AC Schärer M Singer HP Müller SR Schwarzenbach RP Sägesser M Ochsenbein U Popow G 《Chemosphere》2002,48(3):307-315
Concentrations of pesticides in Swiss rivers and lakes frequently exceed the Swiss quality goal of 0.1 microg/l for surface waters. In this study, concentrations of various pesticides (e.g., atrazine, diuron, mecoprop) were continuously measured in the effluents of waste water treatment plants and in two rivers during a period of four months. These measurements revealed that in the catchment of Lake Greifensee, farmers who did not perfectly comply with 'good agricultural practice' caused at least 14% of the measured agricultural herbicide load into surface waters. Pesticides, used for additional purposes in urban areas (i.e. protection of materials, conservation, etc.), entered surface waters up to 75% through waste water treatment plants. 相似文献
172.
Beta diversity at different spatial scales: plant communities in organic and conventional agriculture. 总被引:1,自引:0,他引:1
Doreen Gabriel Indra Roschewitz Teja Tscharntke Carsten Thies 《Ecological applications》2006,16(5):2011-2021
Biodiversity studies that guide agricultural subsidy policy have generally compared farming systems at a single spatial scale: the field. However, diversity patterns vary across spatial scales. Here, we examined the effects of farming system (organic vs. conventional) and position in the field (edge vs. center) on plant species richness in wheat fields at three spatial scales. We quantified alpha-, beta-, and gamma-diversity at the microscale in 800 plots, at the mesoscale in 40 fields, and at the macroscale in three regions using the additive partitioning approach, and evaluated the relative contribution of beta-diversity at each spatial scale to total observed species richness. We found that alpha-, beta-, and gamma-diversity were higher in organic than conventional fields and higher at the field edge than in the field center at all spatial scales. In both farming systems, beta-diversity at the meso- and macroscale explained most of the overall species richness (up to 37% and 25%, respectively), indicating considerable differences in community composition among fields and regions due to environmental heterogeneity. The spatial scale at which beta-diversity contributed the most to overall species richness differed between rare and common species. Total richness of rare species (present in < or = 5% of total samples) was mainly explained by differences in community composition at the meso- and macroscale (up to 27% and 48%, respectively), but only in organic fields. Total richness of common species (present in > or = 25% of total samples) was explained by differences in community composition at the micro- and mesoscale (up to 29% and 47%, respectively), i.e., among plots and fields, independent of farming system. Our results show that organic farming made the greatest contribution to total species richness at the meso (among fields) and macro (among regions) scale due to environmental heterogeneity. Hence, agri-environment schemes should exploit this large-scale contribution of beta-diversity by tailoring schemes at regional scales to maximize dissimilarity between conservation areas using geographic information systems rather than focusing entirely at the classical local-field scale, which is the current practice. 相似文献
173.
Glenn E. Moglen Steven A. Gabriel Jose A. Faria 《Journal of the American Water Resources Association》2003,39(4):947-959
ABSTRACT: Increasing awareness about the problems brought on by urban sprawl has led to proactive measures to guide future development. Such efforts have largely been grouped under the term “Smart Growth.” Although not widely recognized as such, the “smart” in Smart Growth implies an optimization of some quantity or objective while undertaking new forms of urban development. In this study, we define Smart Growth as that development plan that leads to the optimal value of a precisely defined measure identified by a stakeholder or stakeholders. To illustrate a formal, quantitative framework for Smart Growth, this study develops definitions of optimal development from the perspectives of four different types of stakeholders: a government planner, a land developer, a hydrologist, and a conservationist subject to certain development constraints. Four different objective functions are posed that are consistent with each of these stakeholders’perspectives. We illustrate the differences in consequences on future development given these different objective functions in a stylized representation for Montgomery County, Maryland. Solutions to Smart Growth from the individual perspectives vary considerably. Tradeoff tables are presented that illustrate the consequences experienced by each stakeholder depending on the viewpoint that has been optimized. Although couched in the context of an illustrative example, this study emphasizes the need to apply rigorous, quantitative tools in a meaningful framework to address Smart Growth. The result is a tool that a range of parties can use to plan future development in ways that are environmentally and fiscally responsible and economically viable. 相似文献
174.
人力资本法评估农业污染地下水环境价值损失 总被引:1,自引:0,他引:1
应用人力资本法(HCA)评估了华北典型高产粮区地下水资源硝酸盐污染的价值损失.引用国外的研究结果,建立了硝酸盐污染浓度与健康损害的剂量反应关系,分病因预测了地下水污染超标区增加的死亡人口数量.按照潜在寿命损失人年(YPLL)的计算方法,构造了人力资本损失总量估算函数.应用该函数评估了研究区农业面源污染地下水资源的价值损失为860.8万元/a,相当于每公顷耕地面积上增加外部环境成本293.9元/a. 相似文献
175.
Jason S. Bergtold Marcellus M. Caldas Ana Claudia Sant’anna Gabriel Granco Vanessa Rickenbrode 《Journal of Land Use Science》2017,12(6):442-456
The expansion of sugarcane production in the Brazilian Cerrado has resulted in indirect land use change (ILUC), occurring when displaced land uses in one location are reallocated to another. Studies, however, usually identify ILUC at the regional or national level far from the original area of a displaced land use. This study examines the occurrence of ILUC due to sugarcane expansion for ethanol production at the farm level in the Brazilian Cerrado. It fills a gap in the literature by examining socioeconomic, policy and farm-level factors that influence ILUC at the farm level in the Brazilian Cerrado using face-to-face enumerated surveys. Results indicate that ILUC did occur at the farm (producer) scale and farmers who undertook ILUC intensified agricultural production on their farms. Results inform policymakers on how the intensification of agricultural practices may make it potentially difficult to keep protected lands out of production, reducing the environmental benefits from sugarcane-based biofuel production. 相似文献
176.
Phosphate rock formation and marine phosphorus geochemistry: the deep time perspective 总被引:1,自引:0,他引:1
Filippelli GM 《Chemosphere》2011,84(6):759-766
The role that phosphorite formation, the ultimate source rock for fertilizer phosphate reserves, plays in the marine phosphorus (P) cycle has long been debated. A shift has occurred from early models that evoked strikingly different oceanic P cycling during times of widespread phosphorite deposition to current thinking that phosphorite deposits may be lucky survivors of a series of inter-related tectonic, geochemical, sedimentological, and oceanic conditions. This paradigm shift has been facilitated by an awareness of the widespread nature of phosphogenesis—the formation of authigenic P-bearing minerals in marine sediments that contributes to phosphorite formation. This process occurs not just in continental margin sediments, but in deep sea oozes as well, and helps to clarify the driving forces behind phosphorite formation and links to marine P geochemistry.Two processes come into play to make phosphorite deposits: chemical dynamism and physical dynamism. Chemical dynamism involves the diagenetic release and subsequent concentration of P-bearing minerals particularly in horizons, controlled by a number of sedimentological and biogeochemical factors. Physical dynamism involves the reworking and sedimentary capping of P-rich sediments, which can either concentrate the relatively heavy and insoluble disseminated P-bearing minerals or provide an episodic change in sedimentology to concentrate chemically mobilized P. Both processes can result from along-margin current dynamics and/or sea level variations. Interestingly, net P accumulation rates are highest (i.e., the P removal pump is most efficient) when phosphorites are not forming. Both physical and chemical pathways involve processes not dominant in deep sea environments and in fact not often coincide in space and time even on continental margins, contributing to the rarity of high-quality phosphorite deposits and the limitation of phosphate rock reserves. This limitation is becoming critical, as the human demand for P far outstrips the geologic replacement for P and few prospects exist for new discoveries of phosphate rock. 相似文献
177.
Jutta Geldermann Robert Gabriel Otto Rentz 《Environmental science and pollution research international》1999,6(2):115-121
The burning of kerosene in jet turbines is investigated for two reference flights with a Boeing 747-400 and an Airbus A320-200,
representing the typical Lufthansa planes for long and middle distance. The ecological evaluation is performed by Life Cycle
Assessment (LCA). Formation of condensation trails, which is a specific environmental impact caused by air traffic, has to
be considered in addition to established LCA impact categories. Based on the ecological assessment, an improvement assessment
is performed. Environmental performance of diesel fuel during the combustion in car engines is analysed based on available
publications. The relevant parameters for the environmental impact of the combustion of diesel (aromatics content, reduction
of sulphur content, the reduction of the density and raising of the cetane number) are discussed with regard to improvements
of the exhaust qualities of kerosene. A reduction of the aromatics content promises to improve the emission of soot which
should be further investigated. 相似文献
178.
Many species show fission-fusion group dynamics because it has clear advantages for flexibly exploiting heterogeneous environments. However, the mechanisms by which these dynamics arise are not well known. We used a hierarchical Bayesian model to disentangle the different influences on spider monkey (Ateles geoffroyi) individual fissions and fusions, including the three dimensions of fission-fusion dynamics (subgroup size, dispersion, and composition). Furthermore, we considered the influences of other individuals also leaving or joining a subgroup at the same time. We found that the most important influence on individual fissions and fusions is whether other individuals are also doing the same. Subgroup size and dispersion did not have clear effects on the probability that an individual fissioned or fusioned, while individuals tended to leave subgroups that were biased toward the opposite sex and to join subgroups that were biased toward their own sex. The networks constructed by the inter-individual influences during fissions and fusions were cohesive and did not show assortativity by sex or by degree. Individuals had a similar degree in both networks and each was influenced by a different set of individuals, suggesting a high fluidity in the social networks. We suggest that these networks reflect the way in which information about the environment flows as individuals follow one another during fissions and fusions. 相似文献
179.
180.
Gabriel G. González Katherina B. Brokordt Federico E. Winkler 《Marine Biology》2010,157(10):2195-2203
Several studies on individual physiological traits assume that past records may predict future performance. Marine mollusks,
as other animals, show a wide range of between- and within-individual variation of physiological traits. However, in this
group, almost nothing is known about the relative influence of genetic factors on that variation. Repeatability (R) is a measure of the consistency of the variation of a trait, which includes its genetic variance and represents the maximum
potential value of its heritability (h
2). Traits that show high inter-individual variation and high repeatability levels could potentially evolve through selection
(natural or artificial). We estimated the repeatability [using intra-class (τ) and Pearson-moment (r) correlation coefficients] of several physiological traits related to energy acquisition and allocation in juvenile Pacific
abalone Haliotis discus hannai, maintained under controlled environment growing systems. In order to estimate the range of the R values and the effect of the time elapsed between measurements on these estimates, we measured these traits monthly during
6 months for each individual. Among the physiological traits, those related to energy allocation like oxygen consumption (standard
metabolic rate, SMR) and ammonium excretion rates, and oxygen/nitrogen ratio (O/N), showed intermediate levels of repeatability
(0.48, 0.55 and 0.39, respectively), when this was estimated by τ coefficient. However, the r estimation showed that SMR and O/N repeatability were significant and high (0.6–0.7 and 0.5–0.7, respectively) during the
first 5 consecutive measurements, decreasing strongly (0.3 and 0.2, respectively) during the last measurement. For ammonia
excretion, although repeatability (r) decreased from 0.8 to 0.5 during the 6 consecutive measurements, they remain significant during the experimental period.
Therefore, our results indicate that for H. discus hannai juveniles, physiological traits like SMR, ammonia excretion and O/N are significantly repeatable (i.e. good predictors of
future measurements) during a period of 4–5 months. These significant repeatability values suggest an important genetic control
upon the phenotypic variation of these physiological traits, and could potentially respond to natural or artificial selection,
and be used in genetic improvement programs. By contrast, those traits related to energy acquisition (i.e. ingestion, absorption
and assimilation) and physiological efficiencies (i.e. net growth and scope for growth) showed very low levels of repeatability
(0–0.07). This indicates that the phenotypic variation of these traits would be more influenced by environment rather than
by genetic factors. 相似文献