Relationships between diversity of grassland vegetation, field characteristics and land use management practices assessed at the farm level

In order to assess the impact of policies to encourage extensification in less favoured areas and improve our knowledge of extensive livestock systems, we analyzed relationships between the diversity of grassland vegetation and land use management practices and field characteristics. This study, conducted on a mountainous area in the centre of France, was based on 149 fields, mainly of natural grasslands belonging to 7 farmers. Regression analyses were performed to analyze the relations between the grassland vegetation types (five types established from the list of dominant species), management practices (cutting versus grazing and fertilization) and the topographic (altitude and aspect) and topologic (slope, distance and surface area) characteristics of the fields. The land use management rules used by the farmers were studied by specifying the grazing management rules of the herd (dairy cows), as well as those for conserved forage (mainly hay or silage) and were identified from observations mentioned on the “grazing schedules”, as well as from interviews at the beginning, in the middle and at the end of the study period. The statistical analysis showed that neither the topographic characteristics of the fields nor the distance from the cowshed or surface area were correlated with the grassland vegetation types. It was the management practices used, largely determined by the field slope, which determined the grassland vegetation type. On the other hand, farmers’ statements showed that the grazing and cutting management rules were mostly determined by the slope of the fields and the distance from the cowshed and, to a lesser extent, by the altitude and aspect. These results showed that the farmers take into consideration environmental differences when choosing fields to allocate for grazing and cutting at different seasons, particularly when they are constrained by these features. Nevertheless, when the constraints were minimal, a wide diversity of grassland vegetation types was also observed. This diversity was a result of attributing different functions to the fields which led to different management practices (defoliation methods and fertilization) and, thus, to different grassland vegetation types. Consequently, for farms where animal feed requirements vary according to the time of the year and the type of animal, we suggest that diversity in the grassland vegetation types is a sound component of these livestock systems.     

豆奶粉废水生物处理技术

维维集团第二生产基地污水处理设施为全国第一套豆奶粉废水处理设施。该设施采用了“ＵＡＳＢ（ＡＦ）—活性污泥法”工艺。其中ＵＡＳＢ（ＡＦ）反应器是国内最大规模的生产性ＵＡＳＢ装置之一。     

PHBV泡沫吸油材料的制备及吸油性能研究

以PHBV为基材 ,在不同的助剂条件下采用真空冷冻干燥制备了几种PHBV泡沫吸油材料 ,并进行了吸油性能的比较。实验结果表明 :以三氯甲烷和乙基纤维素为助剂制备的PHBV泡沫吸油材料的吸油率、二次吸油率随着助剂量的增加而有所提高 ,而以乙酸纤维素为助剂制备的PHBV泡沫吸油材料的吸油率、二次吸油率随着助剂量的增加而有所降低 ,三者保油率的变化不明显。当达到最佳配比时 ,三种助剂制备的PHBV泡沫在 2 6℃原油下的吸油率可达 2 0倍 ,在 17℃原油下的吸油率可达 30倍。从吸油性能、成本和环保等方面综合考虑 ,以乙酸纤维素作为助剂的制备方法为最佳     

抚顺县生态建设影响因素分析及创建构想

通过分析抚顺县生态县建设有利因素和制约因素，提出了抚顺县生态县建设构筑资源保障体系、循环经济体系、环境保护体系、生态安全体系、生态人居体系和生态文化体系的创建构想。     

鄱阳湖围垦的洪水位效应

为解决鄱阳湖围垦造成的湖泊土地资源开发与湖区生态环境遭受破坏的尖锐矛盾，利用水文学方法，计算出典型年洪水位在不同围垦背景下的洪水位过程，用以确定围垦的洪水位效应，并据此建立洪水位围垦效应与围垦面积的关系；估算再围垦的洪水位效应和退垦还湖效益及湖区大中型圩堤的抗洪能力，提出鄱阳湖区当前适宜退垦还湖面积为４５０ｋｍ＾２的定量依据。     

土壤可蚀性（K）值图编制方法的初步研究

利用土壤普查图件和剖面理化分析的成果资料编制了土壤可蚀性（Ｋ）值图，介绍了求取剖面点Ｋ值的查图表法、图斑分并与图斑Ｋ值的确定原则和编制程序等，应用上述方法，完成了我国第一张地区级Ｋ值图，经分析，与公式算法比，查图表法的Ｋ值精度为８５．４％，与径流小区实测值比，用Ｋ值图上相应Ｋ值监测的土壤年流失量的精度为８６．０％。     

A feasibility study on cleaning Pb-contaminated soil with chelating agents

ＡｆｅａｓｉｂｉｌｉｔｙｓｔｕｄｙｏｎｃｌｅａｎｉｎｇＰｂ－ｏｎｔａｍｉｎａｔｅｄｓｏｉｌｗｉｔｈｃｈｅｌａｔｉｎｇａｇｅｎｔｓＺｈｕＫｕｎ（ＤｅｐａｒｔｍｅｎｔｏｆＥｎｖｉｒｏｎｍｅｎｔａｌＥｎｇｉｎｅｅｒｉｎｇ，ＬａｎｚｈｏｕＲａｉｌｗａｙＣｏｌ...     

前混合磨料射流切割系统的研究

磨料射流切割系统具有很多独特的优点并有广阔的应用前景。通过对几种前混合磨料射流切割系统的分析探讨，提出了在工业应用前必须解决的三个问题：喷嘴磨损、磨料浓度的调节控制和磨料输入，以及解决这些问题的一些方法。     

废旧巷道对含尘气流自净特性的研究

着重研究了废旧巷道对含尘气流的自净特性,进而对利用旧巷自净进行受控循环通风的设想进行探讨;在对浓度场和流体场测试的基础上,建立了粒子在废旧巷道沉降的紊流弥散模型,对边界条件进行了正确的假设,得出了稳态时的自净效率公式;导出了风量与巷道体积的关系表达式。     

浅谈MTBE汽油添加剂的应用对环境的影响

介绍了MTBE汽油添加剂净化汽车尾气的作用,分析污染地下水源和遭到禁用的原因,提出建议.