密云水库上游流域土壤有机碳和全氮密度影响因素研究

为揭示影响密云水库上游流域土壤有机碳(soil organic carbon,SOC)和全氮(total nitrogen,TN)密度的主要因子,采用野外采样、实验室分析和数理统计分析相结合的方法,研究了气候(温度和降水)、地形(海拔和坡度)、土壤理化性质(土壤容重、含水量、pH值和黏粒含量)以及土地利用方式等因素对SOC和TN密度的影响.结果表明,密云水库上游流域森林、草地、农田这3种土地利用类型表层(0～20 cm)SOC密度分别为4.77、6.79和2.90 kg.m-2,TN密度分别为0.41、0.69和0.30kg.m-2,3种土地利用类型之间SOC和TN密度差异显著(P<0.05);土壤含水量、土地利用方式、坡度、土壤pH值和黏粒含量是影响SOC密度的主要因子,土地利用方式、土壤黏粒含量和含水量则是影响TN密度的主要因子;气候、地形、土壤理化性质等区域环境因子共同解释了SOC和TN密度变异性的63.6%和53.4%,而环境因子和土地利用方式对SOC和TN密度变异性的综合解释程度分别为67.6%和57.8%.土地利用对SOC和TN密度变异性的贡献相对于环境因子而言较小,因此,建立高空间分辨率的区域环境因子数据库将是精确估算区域土壤碳氮贮量的关键环节.     

Spatial relationships between alcohol outlet densities and drunk driving crashes: An empirical study of Tianjin in China

Introduction: Numerous studies have demonstrated the close relationship between alcohol availability and alcohol-related crashes. However, there is still a lack of spatial empirical analysis regarding this relationship, particularly in large cities of developing countries. Differences in alcohol outlets and drinking patterns in these cities may lead to quite different patterns of crash outcomes. Method: 3356 alcohol-related crashes were collected from the blood-alcohol test report of a forensic institution in Tianjin, China. Density of alcohol outlets such as retail locations, entertainment venues, restaurants, hotels, and companies were extracted based on 2114 Traffic Analysis Zones (TAZ) together with the residential and demographic characteristics. After applying the exploratory spatial data analysis, this research developed and compared the traditional Ordinary Least Square model (OLS), Spatial Lag Model (SLM), Spatial Error Model (SEM) and Spatial Durbin Model (SDM) to explore spatial effects of all the variables. Results: The results of incremental spatial autocorrelation show that the most significant distance threshold of alcohol-related roadway traffic crashes is 3 km. The SDM is found to be the optimal spatial model to characterize the relationship between alcohol outlets and crashes. The number of alcohol-involved traffic crashes is positively related to population density and retail density, but negatively related to the company density, hotel density, and residential density within the same TAZ. Meanwhile, dense population and hotels have reverse spillover effects in adjacent zones. Conclusions: The significant spatial direct effect and spillover effect of alcohol outlet densities on drunk driving crashes should not be neglected. These findings could help improve transportation planning, traffic law enforcement and traffic management for large cities in developing countries.     

场地参数对地下水污染物健康风险评价影响的初步研究

通过单变量分析,考察含水率、容重和地下水埋深对挥发性有机污染物风险控制值的影响,结果表明土壤含水率、土壤容重和地下水埋深与风险控制值为正相关关系,土壤含水率和容重在超过某一阈值后,微小变化会使风险控制值产生较大的波动,因此建议在实际调查过程中提高水文地质勘察取样和测试质量,获得高代表性的数据,减少风险控制值的不确定性。     

环境监测水质采样质量管理探讨

在社会的不断发展中,人们的生活质量和水平得到了很大提升,但随之而来的环境污染问题也逐渐严重,尤其是水资源污染。如果水资源受到严重污染,将会对社会发展与人类发展产生影响。基于此,在环境监测中,要加强水质监测。本文基于对环境监测水质采样质量管理的研究,首先阐述了环境监测水质采样质量管理的基本内容,然后分析了环境监测水质采样质量管理影响因素,最后提出了促进环境监测水质采样质量管理工作有序进行的措施,包括加强设备管理工作、加强水质样本规范等。     

水稻光合同化碳在土壤不同粒径、密度分组中的分配特征

水稻生长影响土壤有机质在土壤及其各组分中的分布,是关系土壤有机质储量的重要因子.为量化水稻光合同化碳在土壤不同粒径和密度组分中的分布,进而为水稻土有机质积累持续机制与固碳潜力研究提供数据支撑,应用14C连续标记示踪技术,以当地主栽水稻品种"中优169"为供试作物,分别选取亚热带区4种典型稻田土壤,通过土壤有机质物理分组方法探讨了水稻根际输入的光合碳在土壤物理组分(粒径、密度)中的含量和分配特征.结果表明,水稻标记种植80 d后,250～2 000μm粒径的SOC14含量范围为118.23～309.94 mg.kg-1,SOC14/SOC的比例范围为0.52%～1.55%,均大于20～250μm、<20μm这2个粒径的SOC14含量和SOC14/SOC的比例,250～2 000μm、20～250μm这2个粒径的轻组组分的SOC14含量均显著大于相应的重组组分的SOC14含量,说明稻田生态系统通过水稻的根际沉积作用将有机碳(水稻光合同化碳)主要固定在大粒径的轻组组分中,从而提高了土壤有机碳含量.相关分析表明,250～2 000μm粒径与其轻、重组组分、<20μm粒径、20～250μm粒径的SOC14含量之间均呈显著性正相关,而<20μm、20～250μm粒径的轻组组分的SOC14含量之间呈极显著性负相关.     

长江南京段水质自动监测点位优化

简述了长江南京段监测断面现状,用相关分析与聚类分析方法对水质监测数据进行了统计分析,对长江南京段水质自动监测优化布点提出了相关建议。     

Wave Processes in Forest Ant Communities

Mechanisms of interspecific territorial interactions have been studied in multispecific communities of forest ants. These interactions occur through the superposition of high-activity waves traveling over the foraging areas of the influents on the intervals between the waves of dominant species. This allows the foraging ants of both species to search their territory in turn. The role of wave processes in communities is discussed.     

Are rapid population estimates accurate? A field trial of two different assessment methods

Emergencies resulting in large-scale displacement often lead to populations resettling in areas where basic health services and sanitation are unavailable. To plan relief-related activities quickly, rapid population size estimates are needed. The currently recommended Quadrat method estimates total population by extrapolating the average population size living in square blocks of known area to the total site surface. An alternative approach, the T-Square, provides a population estimate based on analysis of the spatial distribution of housing units taken throughout a site. We field tested both methods and validated the results against a census in Esturro Bairro, Beira, Mozambique. Compared to the census (population: 9,479), the T-Square yielded a better population estimate (9,523) than the Quadrat method (7,681; 95% confidence interval: 6,160-9,201), but was more difficult for field survey teams to implement. Although applicable only to similar sites, several general conclusions can be drawn for emergency planning.     

背角无齿蚌净化养殖水体中的重金属

通过建立微型生态系统,研究不同养殖密度和处理时间的背角无齿蚌(Anodonta woodiana)对大宗淡水鱼养殖池塘水体中重金属的净化效果.结果显示,背角无齿蚌对重金属的净化效果受到处理时间和养殖密度的显著影响(PPP3和22.77 d、40 ind./m3和19.78 d时,对Cr和Zn的去除率可提升至80.3%和81.8%.本研究表明背角无齿蚌有潜力用于养鱼水体重金属的净化.