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91.
The effects of livestock grazing on selected riparian and stream attributes, water chemistry, and algal biomass were investigated
over a two-year period using livestock enclosures and by completing stream surveys in the Cypress Hills grassland plateau,
Alberta, Canada. Livestock enclosure experiments, partially replicated in three streams, comprised four treatments: (1) early
season livestock grazing (June–August), (2) late season livestock grazing (August–September), (3) all season grazing (June–September),
and (4) livestock absent controls. Livestock grazing significantly decreased streambank stability, biomass of riparian vegetation,
and the extent to which aquatic vegetation covered the stream channels compared with livestock-absent controls. Water quality
comparisons indicated significant differences among the four livestock grazing treatments in Battle and Graburn creeks but
not in Nine Mile Creek. In Graburn Creek, the concentration of total phosphorus in the all-season livestock grazing treatment
was significantly higher than that in the livestock-absent control, and the early season and late season grazing treatments.
Concentrations of soluble reactive phosphorus in the all-season livestock grazing treatment also exceeded that in livestock-absent
control. In contrast, differences in water quality variables in the remaining 22 comparisons (i.e., 22 of the total 24 comparisons)
were minor even when differences were statistically significant. Effects of livestock grazing on algal biomass were variable,
and there was no consistent pattern among creeks. At the watershed scale, spatial variation in algal biomass was related (P < 0.05) with concentrations of NO2
− + NO3
− and soluble reactive phosphorus in two of the four study creeks. Nutrient diffusing substrata experiments showed that algal
communities were either nitrogen-limited or not limited by nutrients, depending on stream and season. 相似文献
92.
为了解辽阳市蔬菜种植和畜禽养殖基地土壤中重金属状况,依据《环境监测分析方法》、《土壤元素的近代分析方法》的要求土壤采样分析。并根据土壤环境质量标准(GB15618-1995),采用Harkanson"潜在生态危害指数法"对土壤中重金属进行生态风险评价。结果表明,在蔬菜种植和畜禽养殖基地所选典型采样点中,重金属含量无超标现象,均属安全范围,对人体及生物无危害。 相似文献
93.
94.
The number of environmental impact assessment (EIA) screenings in Denmark has increased dramatically since 2000. This is a consequence of increased pig production as well as the concentration of production on larger farms. In the same period, EIA rules have developed primarily due to an increased focus on the protection of groundwater and Natura 2000 sites. In particular, the implementation of Natura 2000 in Danish legislation has increased the demands on many farms. In its rulings on appealed cases, the Nature Protection Board of Appeal has strengthened its demands, and this is mirrored in screening practices. In this paper, the demands formulated in the guidelines of local authorities were analysed in order to investigate how the protection of groundwater, coastal waters, lakes and Natura 2000 sites develops through EIA screening. It is concluded that the level of protection has improved, and that the main cause for this is not EIA regulations as such, but the positive role which the implementation of the Natura 2000 objectives has played in this development. However, it was also found that the formulation of demands varies greatly between the counties, thus often resulting in ambiguity and leaving room for quite different practices in different counties. 相似文献
95.
Ramona Maggini Anthony LehmannMarc Kéry Hans SchmidMartin Beniston Lukas JenniNiklaus Zbinden 《Ecological modelling》2011,222(1):21-32
Climate change is affecting biodiversity worldwide inducing species to either “move, adapt or die”. In this paper we propose a conceptual framework for analysing range shifts, namely a catalogue of the possible patterns of change in the distribution of a species along elevational or other environmental gradients and an improved quantitative methodology to identify and objectively describe these patterns. Patterns are defined in terms of changes occurring at the leading, trailing or both edges of the distribution: (a) leading edge expansion, (b) trailing edge retraction, (c) range expansion, (d) optimum shift, (e) expansion, (f) retraction, and (g) shift. The methodology is based on the modelling of species distributions along a gradient using generalized additive models (GAMs). Separate models are calibrated for two distinct periods of assessment and response curves are compared over five reference points. Changes occurred at these points are formalized into a code that ultimately designates the corresponding change pattern. We tested the proposed methodology using data from the Swiss national common breeding bird survey. The elevational distributions of 95 bird species were modelled for the periods 1999-2002 and 2004-2007 and significant upward shifts (all patterns confounded) were identified for 35% of the species. Over the same period, an increase in mean temperature was registered for Switzerland. In consideration of the short period covered by the case study, assessed change patterns are considered to correspond to intermediate patterns in an ongoing shifting process. However, similar patterns can be determined by habitat barriers, land use/land cover changes, competition with concurrent or invasive species or different warming rates at different elevations. 相似文献
96.
工业事故演变混沌特性研究 总被引:1,自引:1,他引:0
混沌与随机是本质上不同的两种特性.区分产生工业事故演变系统的混沌性和随机性是进行工业事故模拟和预测的基础.本文通过对工业事故演变特性进行分析,初步结果表明,工业事故演变具有混沌动力系统的一些特征,提出通过相空间重构及Lyapunov指数来判定工业事故演变的混沌特性. 相似文献
97.
Despite the promotion of Cleaner Production (CP) by government, academia and research institutions in the past few years, only a small number of Vietnamese industries have adopted it. This paper explores why CP has not been widely adopted by industry through an examination of the root causes preventing effective CP implementation in Vietnam. The paper concludes with possible directions for improving the effectiveness and sustainability of CP programs in Vietnam through training and education. 相似文献
98.
通过对各行业工伤事故伤亡人数和损失后果的广泛调查,及其对不同行业和各类企业影响范围和程度的比较分析,全面识别工伤事故给企业经济效益导致的损失,并科学地评价了对行业生产发展的影响。 相似文献
99.
A. A. Katsanos N. Panayotakis M. Tzoumezi E. Papadopoulou-mourkidou G. A. Mourkides 《Chemistry and Ecology》1987,3(1):75-100
In the industrial zone of Ptolemais, Greece there are two coal-fired power plants, one nitrogen-fertilizer producing plant and a factory making coal-bricks. The industrial and the municipal waste effluents of this area are discharged into the lake Vegoritis via a small stream named Solou. Water and core or grab sediment samples taken from the Solou stream and Vegoritis Lake were analyzed for metallic elements by the proton induced X-ray emission (PIXE) method and the different pollution sources of the area under study, as far as metal pollution is concerned, were tentatively identified. The communities contribute to the pollution with loads of Pb and Ni; Ca, Cr, and Mo are contributed mainly by industries, while Fe, Zn, Mn, Sr, and Br have their origin to both sources. Also the sediment enrichment factors (SEF) are calculated and discussed. 相似文献
100.
通过静态(10 d)和动态(105 d)两个阶段成功启动自行设计的亚硝化-厌氧氨氧化一体化反应器,并进行了处理禽畜养殖场废水的研究。反应器运行稳定后,分别考察了溶解氧(DO)和水力停留时间(HRT)对一体化反应器运行性能的影响。结果表明,当供氧段DO为1.5 mg/L~2.0 mg/L以及HRT在22 h~26 h时,反应器运行效果良好;采用一体化反应器在常温18℃~30℃,供氧段DO为1.5 mg/L~2.0 mg/L,废水HRT约24h条件下处理某禽畜养殖场厌氧池出水,COD、NH4^+-N和TN平均去除率分别为75.10%、85.77%、69.28%,脱氮效果明显,反应器氮容积负荷达0.14 kg/m^3.d。 相似文献