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741.
Swine (Sus scofa domestica) lagoon effluent is a valuable resource. In the U.S. Mid-South it is applied from April to September to fertilize grass hay in spray-irrigated fields. Lagoon levels of nutrients and bacteria, and soil levels of nutrients have been documented, but little was known of effluent bacterial levels in soil. The present study examined levels of selected effluent bacteria and nutrients in soils inside and outside spray fields after >15 yr of effluent irrigation. Samples were collected February to March 2009 from contiguous soils spanning adjacent irrigated and nonirrigated areas. Separate soil cores for bacterial and nutrient tests were collected in pairs <10 cm apart. Five cores each were collected at 15-m intervals and combined, respectively, to comprise inside and outside samples from each of 20 soils (four each from five farms/spray fields). Analyses of data combined across all soils showed higher pH and Mehlich-3-extracrable (M3-) P, Mg, K, Na, Cu, and Zn inside than outside spray fields, while total N, total C, M3-Ca, and M3-Mn did not differ. Bacterial levels were higher inside than outside spray fields for heterotrophic plate counts, thermotolerant coliforms, Staphylococcus spp., and Clostridium perfringens, but levels of Escherichia coli and Enterococcus spp. were not different. Cultural presence/absence tests for three pathogens (Listeria spp., Campylobacter spp., and Salmonella spp.) detected only Listeria spp., which did not differ inside (23% positive samples) and outside (28% positive). Molecular tests detected all three pathogens at low levels that were not different inside and outside. We found no evidence of cumulative buildup of Campylobacter spp., Listeria spp., or Salmonela s. in spray field soils.  相似文献   
742.
An ecological perspective on nanomaterial impacts in the environment   总被引:1,自引:0,他引:1  
Growing concerns over the potential for unintended, adverse consequences of engineered nanoparticles (ENPs) in the environment have generated new research initiatives focused on understanding the ecological effects of ENPs. Almost nothing is currently known about the fate and transport of ENPs in environmental waters, soils, and sediments or about the biological impacts of ENPs in natural environments, and the bulk of modern nanotoxicogical research is focused on highly controlled laboratory studies with single species in simple media. In this paper, we provide an ecological perspective on the current state of knowledge regarding the likely environmental impacts of nanomaterials and propose a strategy for making rapid progress in new research in ecological nanoscience.  相似文献   
743.
This work was undertaken to analyze nutrient contents of vegetation in an alpine meadow—Tungnath, North-West Himalaya, India. The study pertains to the uptake, transfer and release of four main macronutrients (organic carbon, total nitrogen, total potassium and total phosphorus) in grazed (exposed to extensive grazing by cattles) and ungrazed (grazing completely prohibited) communities. Mineral concentration was recorded higher for the ungrazed sites compared to the grazed sites, and maximum standing state of nutrients was found in roots. Belowground compartment (roots) contributed maximum share of mineral elements to soil. Litter nutrients release was low because of low microbial activity and continuous removal of phytomass. Observations reveal that there was very little amount of nutrient release from phytomass and vegetation in alpine are very poor source of mineral recycling. Low transfer rate of minerals from one compartment to other is adequate for greater amount of these minerals that are translocated back into the storage organs. A small proportion get removed through rain splash or through the removal of hay during grazing as relatively high release rates in ungrazed sites when compared to grazed sites was observed. This translocation can be considered as an important adaptation in alpine plants for survival during adverse environmental conditions, against all types of biotic pressures and also for regeneration in the forthcoming growing season.  相似文献   
744.
745.
In recent decades, many changes have occurred in the approach to financing and operating water services in developing countries. The demand‐responsive approach is now adopted in many countries in a context of donor‐supported decentralization processes, which gives more responsibility to end users. However, the government's responsibility at different levels is enforced by the international recognition of the human right to water. This paper examines specific actions that build the role of local government authorities in this scenario. A collaboration between an international NGO and a rural district in Tanzania from 2006 to 2009 is used as an action research case study that is representative of local capacity‐building needs in decentralized contexts and rural areas. Three main challenges were detected: i) lack of reliable information; ii) poor allocation of resources in terms of equity; and iii) lack of long‐term community management support from the district. Two mechanisms were established: i) water point mapping as a tool for information and planning; and ii) a District Water and Sanitation Unit Support (DWUS) for community management. The results show how the framework provided by the goal of human right to water helps to define useful strategies for equity‐oriented planning and post‐project support at the local level.  相似文献   
746.
The effects of experimentally elevated O3 on soil respiration rates, standing fine-root biomass, fine-root production and δ13C signature of newly produced fine roots were investigated in an adult European beech/Norway spruce forest in Germany during two subsequent years with contrasting rainfall patterns. During humid 2002, soil respiration rate was enhanced under elevated O3 under beech and spruce, and was related to O3-stimulated fine-root production only in beech. During dry 2003, the stimulating effect of O3 on soil respiration rate vanished under spruce, which was correlated with decreased fine-root production in spruce under drought, irrespective of the O3 regime. δ13C signature of newly formed fine-roots was consistent with the differing gs of beech and spruce, and indicated stomatal limitation by O3 in beech and by drought in spruce. Our study showed that drought can override the stimulating O3 effects on fine-root dynamics and soil respiration in mature beech and spruce forests.  相似文献   
747.
The environmental implications of mining activities are of worldwide concern. An environmental evaluation at the basin level was conducted because of widespread mining in Cajamarca in Northern Peru. A sediment monitoring program was developed at the Jequetepeque basin, located in Cajamarca. A total of 16 sites were monitored at three different times between June 2009 and July 2010, and a total of 42 samples were collected. All samples were analyzed by microwave digestion and by a sequential extraction scheme following the three-stage European Community Bureau of Reference (three-stage BCR) protocol. Trace element mobilization from the sediments to the water column was assessed by the risk assessment code (RAC). Spatial and temporal distribution of trace elements was evaluated by principal component analysis and hierarchical cluster analysis. Cd, Zn, As, and Pb showed the highest concentrations independent of season. Notably, Cu concentration and mobility increased during the wet season for all samples. Additionally, Hg concentration and mobility increased during the wet season near the mine sites. According to the enrichment factor, the highest enrichments of Cd, Zn, Pb, and As were related to mine runoff. The effect of trace elements near the mine sites at the Jequetepeque basin was considered a significant threat to the environment due to Cd, Zn, Pb, and As, and the concentrations of Cu and Hg were also considered a concern. This work establishes a baseline for the environmental quality status of the Jequetepeque basin that may support water quality management in Peru.  相似文献   
748.
Hypoxia has occurred intermittently over the Holocene in the Baltic Sea, but the recent expansion from less than 10 000 km2 before 1950 to >60 000 km2 since 2000 is mainly caused by enhanced nutrient inputs from land and atmosphere. With worsening hypoxia, the role of sediments changes from nitrogen removal to nitrogen release as ammonium. At present, denitrification in the water column and sediments is equally important. Phosphorus is currently buried in sediments mainly in organic form, with an additional contribution of reduced Fe-phosphate minerals in the deep anoxic basins. Upon the transition to oxic conditions, a significant proportion of the organic phosphorus will be remineralized, with the phosphorus then being bound to iron oxides. This iron-oxide bound phosphorus is readily released to the water column upon the onset of hypoxia again. Important ecosystems services carried out by the benthic fauna, including biogeochemical feedback-loops and biomass production, are also lost with hypoxia. The results provide quantitative knowledge of nutrient release and recycling processes under various environmental conditions in support of decision support tools underlying the Baltic Sea Action Plan.  相似文献   
749.
The Baltic Sea Action Plan (BSAP) requires tools to simulate effects and costs of various nutrient abatement strategies. Hierarchically connected databases and models of the entire catchment have been created to allow decision makers to view scenarios via the decision support system NEST. Increased intensity in agriculture in transient countries would result in increased nutrient loads to the Baltic Sea, particularly from Poland, the Baltic States, and Russia. Nutrient retentions are high, which means that the nutrient reduction goals of 135 000 tons N and 15 000 tons P, as formulated in the BSAP from 2007, correspond to a reduction in nutrient loadings to watersheds by 675 000 tons N and 158 000 tons P. A cost-minimization model was used to allocate nutrient reductions to measures and countries where the costs for reducing loads are low. The minimum annual cost to meet BSAP basin targets is estimated to 4.7 billion €.  相似文献   
750.
In the South of Italy, it is common for farmers to burn pruning waste from olive trees in spring. In order to evaluate the impact of the biomass burning source on the physical and chemical characteristics of the particulate matter (PM) emitted by these fires, a PM monitoring campaign was carried out in an olive grove. Daily PM10 samples were collected for 1 week, when there were no open fires, and when biomass was being burned, and at two different distances from the fires. Moreover, an optical particle counter and a polycyclic aromatic hydrocarbon (PAH) analyzer were used to measure the high time-resolved dimensional distribution of particles emitted and total PAHs concentrations, respectively. Chemical analysis of PM10 samples identified organic and inorganic components such as PAHs, ions, elements, and carbonaceous fractions (OC, EC). Analysis of the collected data showed the usefulness of organic and inorganic tracer species and of PAH diagnostic ratios for interpreting the impact of biomass fires on PM levels and on its chemical composition. Finally, high time-resolved monitoring of particle numbers and PAH concentrations was performed before, during, and after biomass burning, and these concentrations were seen to be very dependent on factors such as weather conditions, combustion efficiency, and temperature (smoldering versus flaming conditions), and moisture content of the wood burned.  相似文献   
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