Farmers' involvement in landscape activities: an analysis of the relationship between farm location, farm characteristics and landscape changes in two study areas in Jutland, Denmark

Farmers are important agents in rural landscape management as they modify landscape elements to suit their needs. The purpose of this study is to investigate if patterns of landscape activities undertaken by farmers are related to certain farm characteristics and if landscape activities vary from one location to another. With this purpose, we investigated the differences between the level of farmers' involvement in landscape activities in two study areas in central Jutland, Denmark. Particular attention was given to the analysis of the type and extent of landscape activities and their relationship with farm characteristics. In both study areas, landscape activities leading to a more extensive type of land use predominate. However, a multivariate analysis implemented on the set of landscape activity data reveals significant differences between the two study areas. Hedgerow planting and removal is more common in S?nder Omme, while pond digging and cultivation of permanent grass lands are characteristic activities in Gadbjerg-Givskud. Moreover, the proportion of farmers involved and the area affected by different landscape activities is larger in S?nder Omme than in Gadbjerg-Givskud. The farms of the two areas are different in terms of production type, size and socio-economic characteristics. These characteristics represent significant relationships with landscape activities. However, they are not sufficient to explain the differences between landscape activities undertaken in the two areas. The differences are caused by unique cultural and biophysical environment, which influence and modify the relationship between farm characteristics and landscape activities in a distinct manner for each study area.     

亚热带小区域水平上土壤质量时空变化的定量化评价

亚热带小区域水平上土壤质量时空变化的定量化评价王效举，龚子同（中国科学院南京土壤研究所，南京２１０００８）ＱｕａｎｔｉｔａｔｉｖｅＥｖａｌｕａｔｉｏｎｏｆＳｏｉｌＱｕａｌｉｔｙＣｈａｎｇｅｓｉｎＴｉｍｅａｎｄＳｐａｃｅａｔａＳｍａｌｌＡｒｅａＬｅｖｅ...     

土地利用变化的数学模型解析

归纳了目前在研究土地利用变化中广泛采用的一些数学模型，解析了每种模型的涵义和意义。按照模型反映的内容不同，将其分为三大类：土地资源数量变化模型、土地资源质量变化模型和土地资源空间变化模型，总结了每类模型的特点和不足之处。     

城市污水管网内生物菌群演替规律

建立了一套长1200 m的城市污水模拟管段,研究了城市污水管网中微生物菌群的沿程演替规律,分析了管网生物膜的pH、DO、厚度、结构及菌群构造的变化情况.结果表明,城市污水管网生物膜pH变化不大,DO由0.35 mg·L-1减小为0.26 mg·L-1,生物膜厚度沿程开始呈增长趋势,平均厚度由300μm增加至800 m处的平均最大厚度560μm,此后呈现降低趋势,这主要与水力冲刷及易吸收营养物质的减少有关,因水力冲刷作用,管网生物膜的初始结构表面平整,随管网长度增加,生物膜呈现疏松构造,从而增大了生物膜比表面积,有利于其生长发育.同样作用下,管网生物膜中的菌群数量也呈现逐渐减少的趋势,生物菌群也发生了较大的变化,其中,200 m处有球菌属、链球菌属、杆菌属、链杆菌属、芽孢杆菌属等菌群,依次400 m、600 m处有肠球菌、脱硫弧菌属、硫单胞菌属,1000 m以后以甲烷球菌、反硝化杆菌、脱氮硫杆菌等厌氧菌为主,沿程菌群种数减少后形成了稳定的菌群结构存在.     

乌海市呼吸道疾病与大气污染的关系

文章通过对乌海市几年来的大气污染变化规律及呼吸道疾病患病率的统计,从乌海市的地理位置、气候特点、工业结构以及环境空气现状,结合乌海市环境监测中心站最近六年的环境空气现状监测结果,从室内、外诸方面探讨了乌海市大气污染现状的成因,提出本市呼吸道疾病患病率与大气污染间的必然联系,并对改善乌海市大气环境现状提出了一些具体措施,为当地政府环保决策提供了参考依据。     

焦作市雨水中重金属特征

对焦作市的降水的pH值、重金属浓度进行监测和分析,并分析其中的重金属浓度变化规律以及与pH值、温度、降雨量、其采样间气象条件的关系,从而推测出当前焦作市的空气污染状况。结果表明：焦作市高新区属于弱酸雨区。其中重金属平均含量大小依次为Fe〉Cu〉Mn〉Zn〉Pb〉Ni;样品中Fe的浓度较高,且受pH值和降雨量的影响较大;Cu的含量基本上均在0．08mg／1-0．10mg／l以内,同时其浓度与降雨量呈正相关;Mn的浓度远远低于Fe的浓度,且在样品5和11中浓度达到峰值;Zn的浓度较高,且在样品5和17中浓度达到峰值。Ni和Pb的含量较低;Pb的浓度与pH值呈负相关,Cu、Zn、Mn、Fe四种金属的浓度变化与pH值的相关性总体上呈正线性相关。其相关系数大小依次RMn〉RFe〉RZn〉RCu;Cu、Zn、Mn、Fe四种金属的浓度变化与样品总体积的相关性总体上Cu、Zn呈正线性相关,Mn、Fe呈负线性相关。其相关系数大小依次RFe〉RMn〉RCu〉RZn.     

太湖典型湖区中胶体有机碳浓度的时空变化

利用切向流超滤技术研究了太湖梅梁湾与贡湖湾2个不同生态类型的典型湖区在不同季节胶体有机碳(COC)的浓度变化,并同步观测了浮游植物、叶绿素(Chla)、悬浮物(SS)等背景指标.结果表明,作为藻型湖区的梅梁湾,其COC浓度夏季最高,秋季最低;作为草型湖区的贡湖湾.其COC浓度在秋季最高,冬季最低;太湖梅梁湾和贡湖湾COC浓度的差异和季节变化有关,夏季梅梁湾COC浓度高于贡湖湾,差异为一年中最大;太湖水体COC浓度和Chla浓度显著正相关(r=0.81,P=0.015),表明浮游植物的生命活动址太湖水体COC的一个重要来源.     

近20a南海赤潮的时空分布特征及原因分析

收集整理了自1980～2004年的南海历次赤潮事件,并对这些赤潮事件在时间和空间的分布特征以及赤潮持续时间长度的变化特征进行了分析;探讨了形成南海赤潮时空分布特征和持续时间长度变化的可能原因.文章认为:赤潮在年度和月份分布不均的原因主要是气候差异以及各月份水文气象要素的主要演变特征不同;赤潮持续时间延长的原因与南海区气候转暖和广东近岸海域水质变差有关.研究发现赤潮事件的月份分布和赤潮持续时间长度存在历史性变异,有关现象值得管理部门和学术界的注意,而其中原因更有待进一步研究.     

Removal of heavy metals from aqueous solution by sawdust adsorption

The adsorption of lead, cadmium and nicel from aqueous solution by sawdust of walnut was investigated. The effect of contact time, initial metal ion concentration and temperature on metal ions removal has been studied. The equilibrium time was found to be of the order of 60 min. Kinetics fit pseudo first-order, second-order and intraparticle diffusion models, hence adsorption rate constants were calculated. The adsorption data of metal ions at temperatures of 25, 45 and 60~C have been described by the Freundlich and Langmuir isotherm models. The thermodynamic parameters such as energy, entropy and enthalpy changes for the adsorption of heavy metal ions have also been computed and discussed. Ion exchange is probably one of the major adsorption mechanisms for binding divalent metal ions to the walnut sawdust. The selectivity order of the adsorbent is Pb（I1）~Cd（II）〉Ni（I1）. From these results, it can be concluded that the sawdust of walnut could be a good adsorbent for the metal ions from aqueous solutions.     

六股河水质污染特征分析

本文通过对不同时段和不同监测点环境监测数据的对比分析,研究了六股河水质污染特征。结果发现：2004～2010年六股河上游和中游符合Ⅱ-Ⅲ类标准,水质保持良好,但部分年份入海口处水质下降,主要污染指标为高锰酸盐指数和石油类。水期监测结果反映了六股河水质主要污染特征：入海口处个别年份丰水期和平水期主要污染物浓度突升是造成水质下降的主要原因。高流量状态下水质下降反映出受面源污染影响特征。入海口小渔场断面污染物入海通量估算结果表明：高锰酸盐指数和石油类入海量总体呈下降趋势,氨氮入海量呈先下降后急剧升高趋势。