锑的表生地球化学行为与环境危害效应

锑(Sb)是一种典型的有毒有害重金属元素。由于自然过程和人为活动的影响,锑及其化合物广泛分布于大气、土壤、水体等表生环境中,锑的环境污染日益严重。Sb不是植物必需元素,但能够被植物体及农作物吸收。Sb对人体和动物体产生慢性毒性及潜在致癌性。本文主要通过分析Sb的主要矿物、锑及其化合物在表生环境中的分布与迁移特性,来阐述人体可能的锑暴露途径及由此产生的环境危害效应。     

大宝山矿区水体中重金属的行为研究

广东大宝山矿区矿山废水的排放使周边生态环境遭受了严重的破坏。水体中重金属Cu、Zn、Cd和Pb的溶解态浓度分别达到13.82、50.83、0.103和2.91 mg.L-1。Cu、Zn、Cd和Pb的溶解态和悬浮态含量沿河流主干道断面呈相似的空间分布规律,上游都是沿水流方向降低,下游因吸附于悬浮物中的重金属重新释放略有增加。悬浮物中重金属元素的化学形态提取和扫描电镜能谱分析(SEM/EDAX)表明:4种重金属元素都以残渣态为主要存在形态,其次为可还原态,个别断面的Cd可还原态甚至超过了残渣态的含量,说明该水体这4种元素对环境都有一定的潜在威胁性。     

郑州园林绿化树木低温寒冻害空间分布特征研究

绿化树木是园林景观的主体部分,同样也是园林建设中的目标植物.然而,绿化植物容易受到低温寒冻害的影响,进而影响园林布局美观.基于此,该文提出郑州园林绿化树木低温寒冻害空间分布特征研究方法,统计郑州园林绿化树木类型,对各样本按照乔木层与灌木层进行分类整理,将频度、显著度、密度等作为计算树木多样性的指标,分析比较结果,根据获...     

Field monitoring of volatile organic compounds using passive air samplers in an industrial city in Japan

Highly portable, sensitive, and selective passive air samplers were used to investigate ambient volatile organic compound (VOC) levels at multiple sampling sites in an industrial city, Fuji, Japan. We determined the spatial distributions of 27 species of VOCs in three campaigns: Mar (cold season), May (warm season), and Nov (mild season) of 2004. In all campaigns, toluene (geometric mean concentration, 14.0microg/m3) was the most abundant VOC, followed by acetaldehyde (4.76microg/m3), and formaldehyde (2.58microg/m3). The spatial distributions for certain VOCs showed characteristic patterns: high concentrations of benzene and formaldehyde were typically found along major roads, whereas high concentrations of toluene and tetrachloroethylene (PCE) were usually found near factories. The spatial distribution of PCE observed was extremely consistent with the diffusion pattern calculated from Pollutant Release and Transfer Register data and meteorological data, indicated that passive air samplers are useful for determining the sources and distributions of ambient VOCs.     

西藏冰湖溃决主要特征

西藏是我国冰湖分布最多的地区。冰湖常发生溃决,其中最典型是终碛冰湖的溃决。冰湖溃决所导致的泥石流,具有突发性强、频率低、洪峰高、流量大、流量过程暴涨暴落和破坏力强及灾害波及范围广等特点。从20世纪30年代中期至今,已查明西藏15个冰川终碛湖至少发生过18次溃决。通过对这些溃决事件的分析,探讨了终碛湖溃决的时空分布特征,发现该事件的发生与气候变化,特别是与气候异常年份有显著的对应关系。结合近年冰湖分布和变化资料,讨论了未来的发展趋势。具体分析了溃决洪水过程和冰湖溃决洪水泥石流演变过程。     

Ambient Aerosol and its Carbon Content in Gainesville, a Mid-Scale City in Florida

Ambient aerosols were collected during 2000–2001 in Gainesville, Florida, using a micro-orifice uniform deposit impactor (MOUDI) to study mass size distribution and carbon composition. A bimodal mass distribution was found in every sample with major peaks for aerosols ranging from 0.32 to 0.56 μm, and 3.2 to 5.6 μm in diameter. The two distributions represent the fine mode (<2.5 μm) and the coarse mode (>2.5 μm) of particle size. Averaged over all sites and seasons, coarse particles consisted of 15% carbon while fine particles consisted of 22% carbon. Considerable variation was noted between winter and summer seasons. Smoke from fireplaces in winter appeared to be an important factor for the carbon, especially the elemental carbon contribution. In summer, organic carbon was more abundant. The maximum secondary organic carbon was also found in this season (7.0 μg m⁻³), and the concentration is between those observed in urban areas (15–20 μg m⁻³) and in rural areas (4–5 μg m⁻³). However, unlike in large cities where photochemical activity of anthropogenic emissions are determinants of carbon composition, biogenic sources were likely the key factor in Gainesville. Other critical factors that affect the distribution, shape and concentration were precipitation, brushfire and wind.     

Desorption of arsenic from drinking water distribution system solids

Previous work has shown that arsenic can accumulate in drinking water distribution system (DWDS) solids (Lytle et~al., 2004) when arsenic is present in the water. The release of arsenic back into the water through particulate transport and/or chemical release (e.g. desorption, dissolution) could result in elevated arsenic levels at the consumers' tap. The primary objective of this work was to examine the impact of pH and orthophosphate on the chemical release (i.e. desorption) of arsenic from nine DWDS solids collected from utilities located in the Midwest. Arsenic release comparisons were based on the examination of arsenic and other water quality parameters in leach water after contact with the solids over the course of 168~hours. Results showed that arsenic was released from solids and suggested that arsenic release was a result of desorption rather than dissolution. Arsenic release generally increased with increasing initial arsenic concentration in the solid and increasing pH levels (in the test range of 7 to 9). Finally, orthophosphate (3 and 5 mg PO₄/L) increased arsenic release at all pH values examined. Based on the study results, utilities with measurable levels of arsenic present in their water should be aware that some water quality changes can cause arsenic release in the DWDS potentially resulting in elevated levels at the consumer's tap.     

The application of generalized linear mixed models to multi-level sampling for insect population monitoring

Iwao's quadratic regression or Taylor's Power Law (TPL) are commonly used to model the variance as a function of the mean for sample counts of insect populations which exhibit spatial aggregation. The modeled variance and distribution of the mean are typically used in pest management programs to decide if the population is above the action threshold in any management unit (MU) (e.g., orchard, forest compartment). For nested or multi-level sampling the usual two-stage modeling procedure first obtains the sample variance for each MU and sampling level using ANOVA and then fits a regression of variance on the mean for each level using either Iwao or TPL variance models. Here this approach is compared to the single-stage procedure of fitting a generalized linear mixed model (GLMM) directly to the count data with both approaches demonstrated using 2-level sampling. GLMMs and additive GLMMs (AGLMMs) with conditional Poisson variance function as well as the extension to the negative binomial are described. Generalization to more than two sampling levels is outlined. Formulae for calculating optimal relative sample sizes (ORSS) and the operating characteristic curve for the control decision are given for each model. The ORSS are independent of the mean in the case of the AGLMMs. The application described is estimation of the variance of the mean number of leaves per shoot occupied by immature stages of a defoliator of eucalypts, the Tasmanian Eucalyptus leaf beetle, based on a sample of trees within plots from each forest compartment. Historical population monitoring data were fitted using the above approaches.     

Characteristics of the Predator–Prey Interactions and the Horizontal Distribution of Macrozoobenthos in Small Lakes of Different Types

The horizontal distribution and quantitative characteristics of macrozoobenthos were studied in small lakes of the Darwin Nature Reserve (southern Vologda oblast). The aggregation index varied in the open areas of acid lakes, which indicated that communities of small acid water bodies were unstable. The aggregation was the lowest in the open area of a neutral lake. In acid lakes, the number and biomass of macroinvertebrates were the highest near the coasts. In the neutral lake, conversely, these values were maximum in open areas and low near the coast due to a strong pressure of predatory invertebrates and fish. An aggregating effect of invertebrate predators was observed near the coasts of lakes of different types.     

山东省主要河流中抗生素污染组成及空间分布特征

采用固相萃取-液相色谱/串联质谱法研究了山东省境内四大流域主要河流中抗生素污染组成及空间分布特征,涉及我国用量最大的6类共20种抗生素。结果表明:20种抗生素均有检出,且大环内酯类、喹诺酮类和四环素类抗生素整体检出浓度较高。就流域而言,半岛诸河流域抗生素污染较小,平均总质量浓度61.4 ng/L;海河流域、小清河流域和淮河流域相对较为严重,平均总质量浓度分别为232、175、118 ng/L。抗生素空间分布呈现一定的规律,检出浓度较高的点位主要集中在人口密集区下游,抗生素污染与周边生活污水、养殖企业废水和城市污水处理厂排水密切相关,而且抗生素组成可从一定程度上反映出污染来源。