Enhancing soil aggregation and acetamiprid adsorption by ecofriendly polysaccharides hydrogel based on Ca2+- amphiphilic sodium alginate

Soil aggregation plays an important role in agricultural production activities. However, the structure of soil aggregation is destroyed by the natural environment and unreasonable farming management, resulting in the loss of water, fertilizers and pesticides in soil. At present, hydrogels have been widely reported to promote the formation of soil aggregation. In this paper, amphiphilic calcium alginate (ASA/Ca²⁺) was applied to promote the formation of soil aggregation and enhance pesticide retention. Initially, an ASA was obtained through the one-pot Ugi condensation (a four-component green chemical reaction). Then, ASA/Ca²⁺ hydrogel is prepared by Ca²⁺ cross-linking. The formation of soil aggregation was determined through the Turbiscan Lab Expert stability analyzer, Confocal Laser Scanning Microscope (CLSM), and Transmission Electron Microscope (TEM). And the effect of soil aggregation on acetamiprid environmental behavior was investigated by adsorption kinetics, adsorption isotherms, and leaching. The results shown that the three-dimensional network structure of ASA/Ca²⁺ hydrogel can promote the formation of soil aggregation. Aggregate durability index (ADI) was 0.55 in the presence of ASA/Ca²⁺ hydrogel, indicating that amphiphilic hydrogel can enhance the stability of soil aggregation. The adsorbing capacity of acetamiprid was 1.58 times higher than pure soil, and the release of acetamiprid only about 20% in the presence of ASA/Ca²⁺ hydrogel. These results would be helpful for the formation of soil aggregation and pesticides adsorption on soil aggregation. Thus, ASA/Ca²⁺ hydrogel is likely to improve soil quality, simultaneously it can minimize the mobility of pesticides in the agricultural system.     

基于径向基函数神经网络方法的城市生态压力预测

针对城市生态压力影响因素复杂,难以对城市未来可持续发展状况做出准确判断的问题,提出了城市生态压力的径向基函数神经网络预测模型,分析了影响城市生态系统的主要因素.以抚顺市1995-2009年数据为基础,验证了模型的准确性并预测了该市2010-2015年城市生态系统的压力情况.研究结果表明:能源消耗指标是影响城市生态系统压力的主要因素;运用径向基函数神经网络模型对训练样本的拟合精度以及对测试样本的仿真精度分别达97.91%和94.16%;抚顺市2015年的人均生态足迹、 生态承载力和生态赤字分别达到7.013、 0.523和6.49 hm²/人.     

Presence of metals in drinking water distribution networks due to pipe material leaching: a review

Drinking water quality should remain constant from the drinking water treatment plant to the consumer's tap. However, water quality characteristics might be affected by interactions with pipe materials. This review describes the iron, copper, lead, zinc, aluminum, chromium, and cadmium in drinking water leached from the pipe material present in drinking water, as well as the factors and mechanisms that affect leaching processes. Data analysis suggests that monitoring the water quality in distribution systems is important for their proper management; however, the low measured concentrations highlight the need for sensitive sensors. In addition, further research is necessary to anticipate possible future effects before the installation of new materials/infrastructure or changes in water source/treatment.     

道路干扰对澜沧江流域景观格局的影响

道路交通在促进人类社会经济发展的同时,也给生态环境带来了诸多影响。研究道路交通的干扰强度、空间格局及其影响,对保护自然环境、维持生态系统健康意义重大。研究基于道路等级、道路所处的环境特征等因素构建道路干扰指数,定量评价了澜沧江流域道路网络的干扰强度,系统分析了流域道路干扰的空间格局特征及其对流域景观的影响。结果表明,澜沧江流域道路网络干扰程度存在明显的区域分异,中游和下游地区明显大于上游地区。流域道路干扰域为边界复杂的不规则多边形,呈现出以离散的强干扰区域为中心,干扰强度向外围逐渐减弱的空间格局。对比不同等级道路干扰域内的景观格局及其变化特征发现,耕地和建设用地等代表人类活动的景观集中分布于道路强干扰区域内,并且强干扰区域内景观组分的变化幅度远大于低干扰区域。从上述分析结果可以看出,道路对其沿线景观格局的变化具有很强的驱动作用,流域道路发展应避开生态环境敏感区域。     

Use of linkage mapping and centrality analysis across habitat gradients to conserve connectivity of gray wolf populations in western North America

Centrality metrics evaluate paths between all possible pairwise combinations of sites on a landscape to rank the contribution of each site to facilitating ecological flows across the network of sites. Computational advances now allow application of centrality metrics to landscapes represented as continuous gradients of habitat quality. This avoids the binary classification of landscapes into patch and matrix required by patch-based graph analyses of connectivity. It also avoids the focus on delineating paths between individual pairs of core areas characteristic of most corridor- or linkage-mapping methods of connectivity analysis. Conservation of regional habitat connectivity has the potential to facilitate recovery of the gray wolf (Canis lupus), a species currently recolonizing portions of its historic range in the western United States. We applied 3 contrasting linkage-mapping methods (shortest path, current flow, and minimum-cost-maximum-flow) to spatial data representing wolf habitat to analyze connectivity between wolf populations in central Idaho and Yellowstone National Park (Wyoming). We then applied 3 analogous betweenness centrality metrics to analyze connectivity of wolf habitat throughout the northwestern United States and southwestern Canada to determine where it might be possible to facilitate range expansion and interpopulation dispersal. We developed software to facilitate application of centrality metrics. Shortest-path betweenness centrality identified a minimal network of linkages analogous to those identified by least-cost-path corridor mapping. Current flow and minimum-cost-maximum-flow betweenness centrality identified diffuse networks that included alternative linkages, which will allow greater flexibility in planning. Minimum-cost-maximum-flow betweenness centrality, by integrating both land cost and habitat capacity, allows connectivity to be considered within planning processes that seek to maximize species protection at minimum cost. Centrality analysis is relevant to conservation and landscape genetics at a range of spatial extents, but it may be most broadly applicable within single- and multispecies planning efforts to conserve regional habitat connectivity.     

基于空气负离子浓度的建筑室内空气清洁度评价

对深圳某办公楼部分房间的空气负离子浓度分布进行了观测研究,利用空气离子单极系数和安倍空气离子评价指数对不同设备制冷的办公室空气质量进行了评价分析。结果表明:自然通风状态下的空气清洁度比机械通风状态下高,利用可再生能源制冷技术的室内空气质量比普通空调制冷技术的好,放置负离子发生器对室内空气质量有显著提高。因此提高室内负离子浓度可以创造舒适的空气环境,并建议把空气负离子浓度列为室内环境的监测和评价指标,为今后城乡建设规划、城市林业规划和环境能源保护提供科学依据和设计思路。     

珠三角工业城市污染物入河量空间特征分析

以东莞市第一次全国污染源普查成果为数据基础,调查估算2010年东莞市33个镇街和25个水功能区的COD、氨氮入河量,并应用GIS技术及相关分析法分析污染物入河量空间分布特征及其影响因素。研究发现：①东莞市各镇街及水功能区的污染物入河量呈明显不均匀分布,人口、GDP是影响污染物入河量空间分布的主要因素。②河网区、非河网区镇街的工业污染物入河量与GDP均呈较好的正相关关系,但非河网区单位污染物入河量GDP产出拟合曲线斜率是河网区的31倍,显示河网区镇街每增长单位污染物入河量所产生的GDP远远小于非河网区,河网区镇街往往付出巨大的污染代价而经济增长却非常有限。     

Optimal locations of monitoring stations in water distribution systems under multiple demand patterns: a flaw of demand coverage method and modification

A flaw of demand coverage method in solving optimal monitoring stations problem under multiple demand patterns was identified in this paper. In the demand coverage method, the demand coverage of each set of monitoring stations is calculated by accumulating their demand coverage under each demand pattern, and the impact of temporal distribution between different time periods or demand patterns is ignored. This could lead to miscalculation of the optimal locations of the monitoring stations. To overcome this flaw, this paper presents a Demand Coverage Index (DCI) based method. The optimization considers extended period unsteady hydraulics due to the change of nodal demands with time. The method is cast in a genetic algorithm framework for integration with Environmental Protection Agency Net (EPANET) and is demonstrated through example applications. Results show that the set of optimal locations of monitoring stations obtained using the DCI method can represent the water quality of water distribution systems under multiple demand patterns better than the one obtained using previous methods.     

基于中国风能资源专业观测网的近地层风切变日变化特征

以中国风能资源专业观测网2009年5至10月10~120 m的梯度风观测数据分析了全国近地层风切变特征,结果表明:①风切变总体呈现规律性变化趋势,即:日出前和日落后切变指数较大,随着近地层温度升高,切变指数逐渐下降,近地层温度达到最高时,切变指数达到最低值,后随着日落、地面温度下降,切变指数逐渐上升,直到次日日出、日落周期;②因局地海(湖)陆分布的差异以及下垫面粗糙程度的不同,切变指数在各地的变化可归纳为如下几种类型:典型陆地型、海陆效应差异型、湖(河)陆效应差异型、特殊地形(峡谷)型、切变指数偏大型和特殊型;③从不同梯度间的风切变特征来看,低层(30 m附近)较为明显,而中高层(50 m和70 m)较小,说明30 m高度为我国近地层风速变化较为明显的层次。该研究资料序列短,可能在反映全国近地层风切变特征的普适性方面还存在一定的不足,但仍可作为我国风能资源丰富区近地层不同梯度间风切变分布和变化特征的重要参考,期望通过该研究的开展为风电场的布设及近地面层风能资源的利用提供技术依据。     

公路路网建设项目声环境影响评价研究

以甘肃省某市新区基础设施建设中的路网建设为例,根据公路路网的交通参数、道路地形地貌条件、路面设施等,利用导则推荐模式预测路网噪声贡献值。该新区路网中道路距离多在500m以上,不论道路平行还是相交,噪声影响以主干道为主,以次干道为辅,相互影响;根据路网噪声环境影响的特点,提出切实可行的声环境影响减缓措施。