基于综合水质标识指数法的四川西充河水质评价

四川省西充河为严重污染河流,选取溶解氧(DO)、氨氮(NH+4-N)、五日生化需氧量(BOD5)、总氮(TN)、总磷(TP)5项指标年平均值,采用综合水质标识指数法,研究了西充河近10年水质状况随时间变化趋势及水污染特征。2003年至2010年水质级别为劣V类,2011年和2012年水质级别为Ⅳ类,水质标识指数Iwq从2003年的12.459逐渐降低到2012年的4.431。西充河近10年水质状况整体呈好转趋势,但未达到国家规定的Ⅲ级水质标准,水质标识指数Iwq结果表明该好转的速度较慢,西充河水质状况有较大的上升潜力和空间。总氮(TN)和氨氮(NH+4-N)为河流主要污染物,为了达到国家Ⅲ级水质标准,西充河的治理已刻不容缓。     

Ionic composition of TSP and PM2.5 during dust storms and air pollution episodes at Xi'an,China

TSP and PM_2.5 samples were collected at Xi'an, China during dust storms (DSs) and several types of pollution events, including haze, biomass burning, and firework displays. Aerosol mass concentrations were up to 2 times higher during the particulate matter (PM) events than on normal days (NDs), and all types of PM led to decreased visibility. Water-soluble ions (Na⁺, NH₄⁺, K⁺, Mg²⁺, Ca²⁺, F^?, Cl^?, NO₃^?, and SO₄^2?). were major aerosol components during the pollution episodes, but their concentrations were lower during DSs. NH₄⁺, K⁺, F^?, Cl^?, NO₃^?, and SO₄^2? were more abundant in PM_2.5 than TSP but the opposite was true for Mg²⁺ and Ca²⁺. PM collected on hazy days was enriched with secondary species (NH₄⁺, NO₃^?, and SO₄²) while PM from straw combustion showed high K⁺ and Cl^?. Firework displays caused increases in K⁺ and also enrichments of NO₃^? relative to SO₄^2?. During DSs, the concentrations of secondary aerosol components were low, but Ca²⁺ was abundant. Ion balance calculations indicate that PM from haze and straw combustion was acidic while the DSs samples were alkaline and the fireworks' PM was close to neutral. Ion ratios (SO₄^2?/K⁺, NO₃^?/SO₄^2?, and Cl^?/K⁺) proved effective as indicators for different pollution episodes.     

Competition for electrons between reductive dechlorination and denitrification

It is common that 2,4,6-trichlorophenol (TCP) coexists with nitrate or nitrite in industrial wastewaters. In this work, simultaneous reductive dechlorination of TCP and denitrification of nitrate or nitrite competed for electron donor, which led to their mutual inhibition. All inhibitions could be relieved to a certain degree by augmenting an organic electron donor, but the impact of the added electron donor was strongest for TCP. For simultaneous reduction of TCP together with nitrate, TCP’s removal rate value increased 75% and 150%, respectively, when added glucose was increased from 0.4 mmol?L^–1 to 0.5 mmol?L^–1 and to 0.76 mmol?L^–1. For comparison, the removal rate for nitrate increased by only 25% and 114% for the same added glucose. The relationship between their initial biodegradation rates versus their initial concentrations could be represented well with the Monod model, which quantified their half-maximum-rate concentration (K _S value), and K _S values for TCP, nitrate, and nitrite were larger with simultaneous reduction than independent reduction. The increases in K _S are further evidence that competition for the electron donor led to mutual inhibition. For bioremediation of wastewater containing TCP and oxidized nitrogen, both reduction reactions should proceed more rapidly if the oxidized nitrogen is nitrite instead of nitrate and if readily biodegradable electron acceptor is augmented.

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Soil CO2 fluxes from direct seeding rice fields under two tillage practices in central China

Agricultural practices affect the production and emission of carbon dioxide (CO₂) from paddy soils. It is crucial to understand the effects of tillage and N fertilization on soil CO₂ flux and its influencing factors for a better comprehension of carbon dynamics in subtropical paddy ecosystems. A 2-yr field study was conducted to assess the effects of tillage (conventional tillage [CT] and no-tillage [NT]) and N fertilization (0 and 210 kg N ha^?1) on soil CO₂ fluxes during the 2008 and 2009 rice growing seasons in central China. Treatments were established following a split-plot design of a randomized complete block with tillage practices as the main plot and N fertilizer level as the split-plot treatment. The soil CO₂ fluxes were measured 24 times in 2008 and 17 times in 2009. N fertilization did not affect soil CO₂ emissions while tillage affected soil CO₂ emissions, where NT had similar soil CO₂ emissions to CT in 2008, but in 2009, NT significantly increased soil CO₂ emissions. Cumulative CO₂ emissions were 2079–2245 kg CO₂–C ha^?1 from NT treatments, and 2084–2141 kg CO₂–C ha^?1 from CT treatments in 2008, and were 1257–1401 kg CO₂–C ha^?1 from NT treatments, and 1003–1034 kg CO₂–C ha^?1 from CT treatments in 2009, respectively. Cumulative CO₂ emissions were significantly related to aboveground biomass and soil organic C. Before drainage of paddy fields, soil CO₂ fluxes were significantly related to soil temperature with correlation coefficients (R) of 0.67–0.87 in 2008 and 0.69–0.85 in 2009; moreover, the Q₁₀ values ranged from 1.28 to 1.55 and from 2.10 to 5.21 in 2009, respectively. Our results suggested that NT rice production system appeared to be ineffective in decreasing carbon emission, which suggested that CO₂ emissions from integrated rice-based system should be taken into account to assess effects of tillage.     

杭州市环保系统人才发展现状与对策

对杭州市环保系统的人才总量、学历结构、专业结构、职称结构和年龄结构等方面作了较详细的分析；针对杭州市环保系统存在的人才总量不足、结构分布不合理和高层次人才匮乏等问题，提出了引进高层次人才、加强教育培训、壮大基层队伍等对策。     

Drought-tolerant <Emphasis Type="Italic">Streptomyces pactum</Emphasis> Act12 assist phytoremediation of cadmium-contaminated soil by <Emphasis Type="Italic">Amaranthus hypochondriacus</Emphasis>: great potential application in arid/semi-arid areas

Microbe-assisted phytoremediation provides an effective approach to clean up heavy metal-contaminated soils. However, severe drought may affect the function of microbes in arid/semi-arid areas. Streptomyces pactum Act12 is a drought-tolerant soil actinomycete strain isolated from an extreme environment on the Qinghai-Tibet Plateau, China. In this study, pot experiments were conducted to assess the effect of Act12 on Cd tolerance, uptake, and accumulation in amaranth (Amaranthus hypochondriacus) under water deficit. Inoculated plants had higher Cd concentrations (root 8.7–33.9 %; shoot 53.2–102.1 %) and uptake (root 19.9–95.3 %; shoot 110.6–170.1 %) than non-inoculated controls in Cd-treated soil. The translocation factor of Cd from roots to shoots was increased by 14.2–75 % in inoculated plants, while the bioconcentration factor of Cd in roots and shoots was increased by 10.2–64.4 and 53.9–114.8 %, respectively. Moreover, inoculation with Act12 increased plant height, root length, and shoot biomass of amaranth in Cd-treated soil compared to non-inoculated controls. Physiochemical analysis revealed that Act12 enhanced Cd tolerance in the plants by increasing glutathione, elevating superoxide dismutase and catalase activities, as well as reducing malondialdehyde content in the leaves. The drought-tolerant actinomycete strain Act12 can enhance the phytoremediation efficiency of amaranth for Cd-contaminated soils under water deficit, exhibiting potential for application in arid and semi-arid areas.     

基于GIS的耕地土壤重金属污染与农业功能定位研究——以山东省聊城市为例

按8km×8km的网格将聊城市耕地分为137个采样点，调查砷、镉、铬、铜、汞、镍、铅、锌等重金属的污染状况。采用国家土壤环境质量标准、农产品安全质量标准和绿色食品产地环境条件作为评价标准，采用单因子指数和综合指数为评价方法进行污染评价。研究表明，聊城市土壤污染强度依次为铜〉镍〉锌〉砷〉铬〉镉〉铅〉汞，但均未超标。以GIS为操作平台显示聊城市重金属空间分布状况，并对区域耕地进行了功能的定位。聊城市西南部土壤质量最优，适宜种植绿色食品；无公害蔬菜和安全粮食种植区在各县市均有不同程度的分布。     

湿式纤维层非稳态过滤净化阻力的研究

在干式纤维层过滤净化阻力的理论基础上,提出清洗水均匀分布于纤维丝表面的基本假设,使湿式过滤中对液滴、液膜、液珠的分析简单具体化。并通过实验结论归纳出净化阻力随时间的变化规律,导出湿式纤维层非稳态过滤净化阻力的表达式,并用实验验证了其准确性。     

温度及外加碳源对生物脱氮除磷过程的影响

针对污水处理厂普遍面临的进水碳源不足及冬季低温时出水氮磷不能稳定达标的问题,研究了温度(21、15和10℃)和外加碳源(乙酸)对活性污泥缺氧条件下反硝化及释磷过程的影响。结果表明,在缺氧条件下投加乙酸,释磷与反硝化反应可同时进行,且乙酸投量的增加仅延长快速碳源反硝化阶段及缺氧释磷阶段的反应时间;温度降低为15℃和10℃时,快速碳源反硝化阶段反硝化速率及缺氧释磷速率较21℃分别降低了约29.2%、42.2%和26.1%、32.3%。当硝态氮目标去除量与磷酸盐目标释放量之比超过5时,乙酸的最优投量以满足反硝化要求为准,计算得出21、15和10℃时常州某城镇污水处理厂乙酸最优投加量计算值约为30、39和46 mg/L。     

脉冲电晕反应器结构对乙硫醇消除效果的影响

研究了脉冲电晕等离子体反应器结构的变化对乙硫醇消除效果的影响规律。结果表明，在反应器内设置折流板，可以增加气流的湍动程度，有利于活性粒子与污染物的充分接触，从而提高消除率。高压电极间距对电晕区范围及消毒效果有较大影响，间距较小将导致各电极产生的电场相互干扰明显，消除率减小；而电极间距过大，虽然电极间电场分布相互干扰小，但是反应器内可排布的电极数减少，总电晕区减少，消除率也减小。根据实验结果，电极间距设置为50 mm比较合理。另外，在相同的电场强度和脉冲频率下，毛刺形高压电极比线电极结构能耗低，能量利用率高。