Soil microbial community structure and function responses to successive planting of Eucalyptus

Many studies have shown soil degradation after the conversion of native forests to exotic Eucalyptus plantations. However, few studies have investigated the long-term impacts of short-rotation forestry practices on soil microorganisms. The impacts of Eucalyptus successive rotations on soil microbial communities were evaluated by comparing phospholipid fatty acid （PLFA） abundances, compositions, and enzyme activities of native Pinus massoniana plantations and adjacent 1st, 2nd, 3rd, 4th generation Eucalyptus plantations. The conversion from P. massoniana to Eucalyptus plantations significantly decreased soil microbial community size and enzyme activities, and increased microbial physiological stress. However, the PLFA abundances formed ＂U＂ shaped quadratic functions with Eucalyptus plantation age. Alternatively, physiological stress biomarkers, the ratios of monounsaturated to saturated fatty acid and Gram＋ to Gram- bacteria, formed ＂∩＂ shaped quadratic functions, and the ratio of cy17：0 to 16： 1ω7c decreased with plantation age. The activities of phenol oxidase, peroxidase, and acid phosphatase increased with Eucalyptus plantation age, while the cellobiobydrolase activity formed ＂U＂ shaped quadratic functions. Soil N：P, alkaline hydrolytic nitrogen, soil organic carbon, and understory cover largely explained the variation in PLFA profiles while soil N：P, alkaline hydrolytic nitrogen, and understory cover explained most of the variability in enzyme activity. In conclusion, soil microbial structure and function under Eucalyptus plantations were strongly impacted by plantation age. Most of the changes could be explained by altered soil resource availability and understory cover associated with successive planting of Eucalyptus. Our results highlight the importance of plantation age for assessing the impacts of plantation conversion as well as the importance of reducing disturbance for plantation management.     

Waste oyster shell as a kind of active filler to treat the combined wastewater at an estuary

Estuaries have been described as one of the most difficult environments on Earth. It is difficult to know how to treat the combined wastewater in tidal rivers at the estuary, where the situation is very different from ordinary fresh water rivers. Waste oyster shell was used as the active filler in this study in a bio-contact oxidation tank to treat the combined wastewater at the Fengtang Tidal River. With a middle-experimental scale of 360 ma/day, the average removal efficiency of COD, BOD, NH3-N, TP and TSS was 80.05%, 85.02%, 86.59%, 50.58% and 85.32%, respectively, in this bio-contact oxidation process. The living microbes in the biofilms on the waste oyster shell in this bio-contact oxidation tank, which were mainly composed of zoogloea, protozoa and micro-metazoa species, revealed that waste oyster shell as the filler was suitable material for combined wastewater degradation. This treatment method using waste oyster shell as active filler was then applied in a mangrove demonstration area for water quality improvement near the experiment area, with a treatment volume of 5 × 10^3 m^3/day. Another project was also successfully applied in a constructed wetland, with a wastewater treatment volume of 1 ×10^3 m^3/day. This technology is therefore feasible and can easily be applied on a larger scale,     

γ-Fe_2O_3/膨胀石墨复合材料吸附废水中六价铬的应用研究

介绍了采用溶胶凝胶法合成新型的复合材料-磁性的γ-Fe_2O_3膨胀石墨(MEG)复合材料。通过采用X-射线衍射(XRD)、扫描电子显微镜(SEM)、透射电子显微镜(TEM)以及X-光电子能谱仪(XPS)对该复合材料MEG进行了表征,结果表明MEG中γ一Fe_2O_3的粒径约为50nm,而且其中γ一Fe_2O_3和膨胀石墨通过C=O相互作用。复合材料MEG作为新型的六价铬吸附剂,通过吸附时间、初始溶液的pH值以及再生性对该吸附过程进行了考察。结果表明:在40 min内MEG吸附六价铬的过程基本达到平衡;在初始溶液的pH为3.5时,MEG对六价铬的最大吸附量可以达到16.4mg/g;而且该复合材料MEG重复使用3次后吸附效果基本没有下降。因此,复合材料MEG对于废水中六价铬的处理有选择性吸附作用,而且初始溶液的pH值对其吸附过程起着重要作用。     

小飞扬草(Euphorbia thymifolia L.)中镉的亚细胞分布及化学形态

采用差速离心法和逐步提取法,分析Cd超积累植物小飞扬草根、茎、叶中Cd的亚细胞分布和化学形态。培养液中Cd浓度5mg/L和10mg/L条件下,在小飞扬草根、茎、叶中,细胞壁和细胞膜是Cd主要的结合场所,含量分别占总量的47.1%～49.0%、39.7%～41.4%、42.9%～56.2%,其次是胞液组分,含量分别占37.5%～41.4%、28.2%～40.7%、35.2%～46.8%,细胞器组分中Cd含量较少。Cd在小飞扬草根、茎、叶中均以氯化钠提取态为主,含量分别占70.5%～84.8%、72.4%～83.0%、50.0%～74.8%。根部各提取态含量依次为CNaCl>CHAC>CEtOH>CHCl>CW>CR,茎、叶中各提取态含量依次为CNaCl>CHCl>CHAC>CEtOH>CW>CR。在小飞扬草中,Cd与细胞壁和细胞膜中的果胶酸和蛋白质等物质结合固定,而进入细胞的Cd大部分与有机酸络合而隔离于液泡内,这可能是小飞扬草忍耐并超积累Cd的机制。     

压缩天然气加气站日常运营环境影响分析——以洛阳市某加气站为例

鉴于压缩天然气(CNG)加气站日常运行对周边环境影响的高风险状态,文章依据洛阳市某CNG加气站生产运营状况,对其运营过程中可能造成的环境影响进行预测、评析,并提出了合理的防范措施。     

活性焦烟气脱硫技术在大型燃煤电站的应用

本文通过分析活性焦烟气脱硫技术的主要原理、工艺流程、主要原料消耗、脱硫副产品综合利用、SO2污染物达标情况,探讨该技术在内蒙古地区大型燃煤电站脱硫工程应用的可行性.     

遥感技术在环境监测中的作用

本文对遥感(3S)技术在环境监测中的应用方法、技术等进行了论述.     

生物炭环境效应和在农业面源污染防治中的作用

生物炭能够延缓肥料养分释放,提高肥料利用率,降低肥料及土壤养分流失,从而减轻农业面源污染。同时,生物炭进入土壤中,实现碳的封存固定,减少碳排放。     

某城市生活垃圾填埋场周边大气环境影响趋势实例研究

针对生活垃圾填埋场的主要恶臭污染物NH3、H2S、臭气浓度,以某城市生活垃圾填埋场为例,采用该填埋场自筹建至今近十年的历史监测数据进行统计分析,给出垃圾填埋场随填埋年龄增长对周边大气环境的影响趋势.     

基于情景分析的城市餐厨垃圾处理方案研究

城市生态环境保护是生态文明建设的重要组成部分之一,而餐厨垃圾是影响城市生态环境的一种主要污染源,因此,有效处理餐厨垃圾也是当前城市生态环境保护的重要内容。本文以重庆市为例,针对其特殊的餐厨垃圾组成成分,调查分析了其主城区餐厨垃圾污染状况及处理难点,提出了3种主要处理方案情景并进行综合效益评价。结果表明建立餐厨垃圾小型处理站是最优方案,其成本效益核算结果说明当政府基金和垃圾产量有限时,也可采用缩小处理站规模以达到最高的组合效益。