Mobility and sulfidization of heavy metals in sediments of a shallow eutrophic lake, Lake Taihu, China

The technique of DGT (diffusive gradients in thin films) using three diffusive gel thicknesses was applied to estimate the mobility and bioavailability of heavy metals in sediments and porewater of Lake Taihu, China. The DGT results showed significantly positive correlations between Co, Pb, Cd and Mn, and Ni and Fe concentrations in porewater. Cu and Zn showed a significantly negative correlation with Mn, due to Cu combination with carbonates and Zn derived from agricultural pollution, respectively. The rank order of average concentrations of Co, Ni and Cd at each station was DGT_1.92 > DGT_0.78 > DGT_0.39, suggesting stronger resupply from sediments to porewater when using thicker diffusive gels. Comparing centrifugation and DGT measurements, Co, Ni and Cd are highly labile; Mn and Fe are moderately labile; and Cu, Zn and Pb are slightly labile. The variations of AVS concentrations in sediment cores indicate that metal sulfides in deeper layers are easily diffused into surface sediments.     

美国新潮:通过明星的嘴和脸来环保

在纽约,人们不得不尝试采取各种形式来推进环境保护工作的进程,八仙过海各显其能.去年7月4日华盛顿庆祝国庆节的游行中,我就亲眼看到一个宣传环保的队伍,队中的每个人都拿着一个垃圾袋,边走边收集游行者和观众丢弃的易拉罐,成为国庆节游行的一个亮点.     

Soil enzyme activities and their indication for fertility of urban forest soil

To reveal the biological characteristics of urban forest soil and the effects of soil enzyme on soil fertility as well as the correlation between physicochemical properties and enzyme activities, 44 urban forest soil profiles in Nanjing were investigated. Basic soil physicochemical properties and enzyme activities were analyzed in the laboratory. Hydrogen peroxidase, dehydrogenase, alkaline phosphatase, and cellulase were determined by potassium permanganate titration, TTC (C₁₉H₁₅N₄·Cl) colorimetry, phenyl phosphate dinatrium colorimetry, and anthrone colorimetry, respectively. The result showed that soil pH, organic carbon (C), and total nitrogen (N) had great effects on hydrogen peroxidase, dehydrogenase, and alkaline phosphatase activities in 0–20 cm thick soil. However, pH only had great effect on hydrogen peroxidase, dehydrogenase, and alkaline phosphatase activities in 20–40 cm thick soil. Hydrogen peroxidase, dehydrogenase, and alkaline phosphatase were important biological indicators for the fertility of urban forest soil. Both in 0–20 cmand 20–40 cmsoil, soil enzyme system (hydrogen peroxidase, dehydrogenase, alkaline phosphatase, and cellulase) had a close relationship with a combination of physicochemical indicators (pH, organic C, total N, available K, available P, cation exchange capacity (CEC), and microbial biomass carbon (C_mic)). The more soil enzyme activities there were, the higher the fertility of urban forest soil.     

使用多边形中空铝坯料冷挤压生产多边形铝螺母的工艺方法

介绍了一种已申请国家专利的铝螺母的加工方法。并就冷挤压时零件的变形、模具机构的设计等作了较为详细的论述。     

国外蒸汽防护服装的研究进展

本文介绍了目前美、日、法等国蒸汽防护服装研究和装备概况,指出了需从蒸汽防护面料的功能设计和蒸汽防护服装的结构设计两方面出发,首先满足蒸汽防护服装的安全防护功能,同时兼顾服装的穿着舒适性.     

我国石油炼化企业主要水污染物排放量核算方法研究

从企业工艺和产品特点出发,分析了石油炼制企业主要水污染物的排放量与企业加工量、加工工艺、加工装置、末端治理设施之间的简单逻辑关系,提出了一种基于企业规模、生产装置特征和污染治理技术的石油炼化企业水污染物排放量复杂系数核算方法。通过与实际监测数据的对比,该方法的误差满足总量核算中石油炼化企业排放量核算的要求,为行业总量减排核算提供了一种新的方法。