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21.
在分析夹潦草堂旅游风景区背景要素和制约因素的基础上,遵循史学文化、知识、淳真自然的三大设计理念,采用圈层递进的总体布局构思,设计了7个主题区域的空间布局,开发出修学旅游、观光旅游、度假旅游、森林探险旅游等四大主导旅游产品。  相似文献   
22.
The Surface Mining Control and Reclamation Act of 1977 requires that coal mine sites in the United States be reclaimed to establish vegetative cover that is diverse, native, and capable of plant succession. However, there is a question as to whether vegetation established on coal mine sites reclaimed with biosolids is diverse and capable of plant succession. The influx of nutrients with the addition of biosolids leads to long-term dominance by early-successional species, most notably grasses, and consequently, a low establishment of woody and volunteer species. Additionally, many grass species commonly planted in reclamation have aggressive growth habits that lead to their dominance in coal mine plant communities. The establishment and growth of selected grass mixes was evaluated to determine whether alternative grass mixes would be less competitive with woody and volunteer species as compared to commonly used grass mixes. Percent vegetative cover, species richness, and the survival of direct-seeded woody species were assessed for each treatment grass mixture. It was found that Poa compressa and a mixture of P. compressa, Panicum virgatum, and Trifolium repens provided adequate coverage while still allowing the highest species richness and survival of woody species. Use of these species mixtures in coal mine reclamation with biosolids in the eastern United States would likely lead to establishment of a more species-rich plant community with a greater woody species component while still providing erosion control and site protection.  相似文献   
23.
对虾暴发性流行病的病因及预防对策分析   总被引:6,自引:2,他引:6  
本文报告了用电子显微镜对1993年对虾暴发性流行病的病原观察结果,确认带包膜的杆状病毒是造成虾病暴发流行的病原。借鉴东南亚各国养虾的经验教训,分析了这次虾病的流行原因是海水富营养化。并结合作者多年从事对虾病害研究工作的实践,讨论了预防对虾暴发性流行病的对策。  相似文献   
24.
Six ponds of age 3 were selected 45 km north from Suzhou in the Tailake region, and research conducted on nitrogen and phosphorus cycling in P. vannanmei(Penaeus vannanme) ponds and M. nipponense(Macrobrachium nipponense) hatchery ponds under normal management. Two treatments each had three replications. The results confirmed that feed was the major path of nitrogen and phosphorus input, each accounted for 61.24%(193.81 kg ha–1) and 81.08%(45.20 kg ha–1) of the total nitrogen and phosphorus input for P. vannanme ponds; the values for M. nipponense ponds were 43.93%(86.31 kg ha–1) and 57.67%(14.61 kg ha–1), respectively. Water pumped into ponds contributed on average 83.57 kg ha–1 nitrogen and 8.48 kg ha–1 phosphorus for P. vannanmei ponds, and 87.48 kg ha–1 nitrogen and 7.00 kg ha–1 phosphorus for M. nipponense hatchery ponds. Shrimp harvest recovered 102.81 kg ha–1 nitrogen (32.94% of the total nitrogen input) and 7.94 kg ha–1phosphorus (14.23% of the total phosphorus input) for P. vannanme ponds; and 43.94 kg ha–1 nitrogen and 4.46 kg ha–1phosphorus for M. nipponense hatchery ponds. The sum of nitrogen losses through volatilization, denitrification and sedimentation was 173.62 and 122.39 kg ha–1, 54.86% and 62.29% of the total nitrogen input for P. vannanme ponds and M. nipponense hatchery ponds, respectively. Sediment accumulated 41.46 and 14.63 kg ha–1 phosphorus, 74.37% and 64.85% of the total phosphorus input for P. vannanm ponds and M. nipponense hatchery ponds. Draining and seeping caused 40.06 kg ha–1 nitrogen (12.66% of total nitrogen input) and 6.36 kg ha–1 phosphorus (11.40% of total phosphorus input) loss to the surrounding water from P. vannanme ponds in 114 days; 30.14 kg ha–1nitrogen (15.34% of the total input) and 4.45 kg ha–1 phosphorus (17.57% of the total input) to channel water from M. nipponense hatchery ponds in 87 days, respectively. Countermeasures for sustainable pond management include improving feeds and feeding, sediment treatments, machine aerating, chemicals with no pollution, and integrated fish-shrimp cultivation. Management of water resources for pond and methods to reduce nitrogen and phosphorus loading into surrounding water from drainage are elucidated.  相似文献   
25.
26.
The USLE/RUSLE support practice factor (P-factor) is rarely taken into account in soil erosion risk modelling at sub-continental scale, as it is difficult to estimate for large areas. This study attempts to model the P-factor in the European Union. For this, it considers the latest policy developments in the Common Agricultural Policy, and applies the rules set by Member States for contour farming over a certain slope. The impact of stone walls and grass margins is also modelled using the more than 226,000 observations from the Land use/cover area frame statistical survey (LUCAS) carried out in 2012 in the European Union.The mean P-factor considering contour farming, stone walls and grass margins in the European Union is estimated at 0.9702. The support practices accounted for in the P-factor reduce the risk of soil erosion by 3%, with grass margins having the largest impact (57% of the total erosion risk reduction) followed by stone walls (38%). Contour farming contributes very little to the P-factor given its limited application; it is only used as a support practice in eight countries and only on very steep slopes. Support practices have the highest impact in Malta, Portugal, Spain, Italy, Greece, Belgium, The Netherlands and United Kingdom where they reduce soil erosion risk by at least 5%. The P-factor modelling tool can potentially be used by policy makers to run soil-erosion risk scenarios for a wider application of contour farming in areas with slope gradients less than 10%, maintaining stone walls and increasing the number of grass margins under the forthcoming reform of the Common Agricultural Policy.  相似文献   
27.
鱼虾贝类立体生态养殖对水质净化作用研究   总被引:1,自引:0,他引:1  
2009年在山东无棣的滨州市水产研究所养殖基地,进行了鱼虾贝类立体生态养殖对水质净化作用的试验,结果表明:鱼虾贝类立体生态养殖与单纯贝类生态养殖对水质的净化作用相比较,鱼虾贝类立体混养对CODMn、BOD5、无机氮、活性磷酸盐、硫化物、挥发酚的去除率明显高于贝类单独养殖的去除率,总磷的去除率二者相差不大,唯单纯贝类养殖对总氮的去除率高于鱼虾贝类立体养殖。  相似文献   
28.
虾池环境生物修复作用菌的模拟应用   总被引:11,自引:1,他引:11  
在模拟条件下,研究了虾池环境生物修复作用菌对对虾养殖环境中虾池有机物的降解过程,结果表明,虾池环境生物修复作用菌能明显改善虾池环境,降低有机物的含量(4d后CODMn的去除率为43.52%)。将大分子的有机物降解为小分子的无机氮等;对虾养殖池中作用菌的使用量以262.5kghm^-2为宜。图3参13  相似文献   
29.
Nutrient Ioadings were measured for surface seawater and bottom sediments of semi-intensive and improved extensive shrimp culture pond, adjacent estuary, and fallow land in the south-east coastal region of Bangladesh during August, 2000--January, 2001 to evaluate the impact of shrimp culture. The mean levels of nutrients found in the pond surface water were 108.780 mg/L for CaCO3, 0.526 mg/L for NH4^ -N, 3.075 wt% for organic carbon, 7.00 mg/L for PO4-P, 5.57 mg/L for NO3-N, and 7.33 mg/L for chlorophyll-a. The maximum mean value of H2S(0.232 mg/L) was found in estuarine water. Nutrients loading were found to be decreased with distance from the shrimp farm discharge unit in estuarine water. The mean level of organic matter, total nitrogen, and organic carbon were found in higher concentrations in sediments of cultured pond compared to bottom soil of adjacent fallow land at the same elevation. Extractable Ca values were found in higher concentration(550.33 ppt) in adjacent fallow land, as the shrimps for molting in shrimp ponds use extractable Ca. The relation between seawater H2S value and sediment pH ( r= -0.94); sediment organic carbon and sediment pH values ( r= -0.76), sediment total nitrogen and sediment pH ( r = - 0.74) were found to be highly negatively correlated. Whereas the relation between seawater H2S value and sediment total nitrogen ( r= 0.92), water NH4^ -N and sediment pH ( r = 0.66) were found to be positively correlated. The results revealed that load of nutrients at eutrophic level in estuarine water, and decrease of soil pH; leading to acid sulphate soil formation indicates a negative impact of shrimp culture.  相似文献   
30.
In this work, the cytotoxicity and toxicity of phosphonium-based deep eutectic solvents (DESs) with three hydrogen bond donors, namely glycerine, ethylene glycol, and triethylene glycol were investigated. The cytotoxicity effect was tested using brine shrimp (Artemia salina). The toxicity was investigated using the two Gram positive bacteria Bacillus subtilis and Staphylococcus aureus, and two Gram negative bacteria Escherichia coli and Pseudomonas aeruginosa. The cytotoxicity of tested DESs was much higher than that of their individual components, indicating their toxicological behavior was different. It was also found that there was toxic effect on the studied bacteria, indicating their potential application as anti-bacterial agents. To the best of our knowledge, this is the first time the cytotoxicity and toxicity of phosphonium-based DESs were studied.  相似文献   
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