退耕还林工程对黄土高原土地利用/覆被变化的影响——以陕西省安塞县为例

退耕还林工程(Sloping land conversion program, SLCP)可快速改变土地利用/覆被格局。论文以黄土高原典型沟壑区--陕西省安塞县为例,利用MSS/TM/ETM+卫星遥感影像,获取研究区6个时期土地利用/覆被的时空信息,通过统计模型,定量分析了研究区SLCP对土地利用/覆被格局的影响。草地、耕地及林地为研究区三大主要土地利用/覆被类型,研究区土地利用/覆被变化整体处于不平衡态势;整个研究时段内,耕地先增后减,整体减少38.4%;林地先减后增,整体增加4.36%;灌木林地和草地减少,而未成林造林地快速增加;SLCP显著加强了耕地的递减趋势,并大幅增加了未成林造林地面积,至2010年未成林造林地面积显著大于天然林地的面积。这些变化可能具有降低土壤侵蚀与产流量、改善土壤结构、增加土壤碳吸收等效应;SLCP能提高农民收入,且大部分农民支持SLCP;但其负面效应亦不可忽视。研究将有助于对SLCP效应的全面理解,并可为该区生态恢复工程的规划与决策及生态环境保护提供参考。     

机动车排放检测和维修制度实施效果分析

实施检测和维修制度是机动车污染控制的重要措施 ,机动车排放检测是检测和维修制度的主要内容 .本研究利用累积分布曲线 ,通过双怠速检测排放限值对各类型高排放车辆的识别率 ,从检测数据、现行标准、上线合格率 3个角度对北京市检测和维修制度的排放限值制定、组织形式和实施效果进行分析 ,提出各受检物排放限值的匹配原则 .     

UV/H2O2降解水中2,4-二氯酚实验研究

研究溶液浊度、pH值及不同光源等因素对 2 ,4 二氯酚降解的影响 ,确定了UV/H2 O2 光氧化降解 2 ,4 二氯酚反应器的水质适用范围 (浊度小于 6NTU)。在 30W的紫外光照射下 ,2 0mg/L 2 ,4 二氯酚 ,H2 O2 的投加剂量为 1 .2 8mg/L时 ,90min内 2 ,4 二氯酚去除率可达到 95 % .实验证明UV/H2 O2 光氧化技术是低浊度水深度处理的一种有效方法 .     

Fractionation of residual Al in natural water treatment from reservoir with poly-aluminum-silicate-chloride (PASiC): Effect of OH/Al, Si/Al molar ratios and initial pH

An aluminum fractionation study was conducted for a surface reservoir water treatment to understand the performance of poly-aluminum-silicate-chloride (PASiC) in terms of the residual Al fractions as a function of initial pH. The coagulation performance expressed as turbidity and organic matter removal was established as supporting data. Some extra data were evaluated in terms of the residual Al ratio of the composite PASiC coagulant. The main residual Al sources were the Al fractions derived from the use of PASiC. The turbidity and organic matter removal ability was optimal at initial pH 6.00-7.00, while the concentrations of various residual Al species and the residual Al ratio of PASiC were minimal at an initial pH range of 7.00-8.00. Under the conditions of OH/Al molar ratio = 2.00 and Si/Al molar ratio = 0.05, PASiC had superior coagulation performance and comparatively low residual Al concentrations. The Al fraction in the composite PASiC coagulant seldom remained under such conditions. Experimental data also indicated that the suspended (filterable) Al fraction was the dominant species, and organic-bound or organo-Al complex Al was considered to be the major species of dissolved Al in water treated by PASiC coagulation. Additionally, the dissolved inorganic monomeric Al species dominated the dissolved monomeric Al fraction.     

Effect of manufacturing methods of AgCl/Al2O3 catalyst on selective catalytic reduction of NOx

The AgCl/Al2O3 catalyst has potential for use in the selective catalytic reduction (SCR) of NOx. A compound hydrocarbon, following oxygenation is used as a type of reducing agent. In this experiment, the AgCl/Al2O3 catalyst was produced by four different methods, and the differences among their reduction catalysis of NOx were compared. Ethanol was used as a type of reducing agent. X-ray diffraction analysis was performed to study the crystalline structure and scanning electron microscope and transmission electron microscope (TEM) were applied to determine the microindentation. The results indicated that, in the range of 350–400°C, there was no significant difference on the NOx reduction rate; however, there was dispersion at high and low temperature ranges. The size of the AgCl particles was about 20–100 nm.     

硝酸盐对矿化垃圾中兼/厌氧甲烷氧化的影响

设计全因子实验研究了NO-3-N对填埋10~12 a的矿化垃圾中兼/厌氧甲烷氧化作用的影响.结果表明,兼/厌氧条件下,NO-3-N能促进矿化垃圾中CH4的去除.初始CH4和NO-3-N对CH4去除和N2产生有明显影响,且两者具有交互作用(P<0.05).CH4去除量随着初始CH4体积分数的增加而增加,添加一定含量的NO-3-N能促进CH4去除,同时通入一定体积分数CH4可以明显促进反硝化作用,说明矿化垃圾中NO-3-N还原能与兼/厌氧甲烷氧化耦合.本实验条件下,初始CH4体积分数为30%,NO-3-N含量为110 mg·kg-1时耦合效应较好.     

Optimization of C/N ratio for preparation of protein-rich and multi-enzymes feed thallus through synergic fermentation of mixed distillers'grains

A new procedure of determining optimal C/N (the rate of carbon source to nitrogen source) of mixed distillers' grains for combined bacteria synergic fermentation is established. At the same time an improved method evaluating bacteria growth, called method of dry cell weighing by filtering is developed. For each combination of C and N , their initial and residual contents before and after fermentation respectively are determined. Then followed the calculation of utilization of C and N sources by the compound bacteria. The optimal C/N is finally located from among the utilization of C and N of several combinations and the weight of produced mass of oven-dried thallus The conditions of fermentation are: inoculum size 10%, temperature 30.0℃, rotational speed 170 r/min, shake culture time 48h. The best results obtained from orthogonal experiments are: maximum mass of oven dried thallus is 14.693g in a liter liquid medium, maximum utilization rate of carbon source is 98.13% and maximum utilization rate of nitrogen is 78.14%. Optimal C/N is 5.1.     

气溶胶中不同类型碳组分粒径分布特征

了解气溶胶碳组分粒径分布特征对于研究区域气溶胶生成转化机制、辐射特性等非常重要,但北京地区针对气溶胶碳组分粒径分布特征的相关研究非常少.本研究利用MOUDI-120采样器在北京地区3个季节开展气溶胶分级样品的采集,并分析其中不同类型的碳组分的含量,进而系统研究不同季节及污染状况下,各碳组分的粒径分布特征、来源及相互关系.结果表明,碳组分主要富集在细粒子中,秋冬季细粒子中碳组分的比重高于夏季.碳组分主要分布在两个模态,即积聚模态和粗模态. OC1和OC2主要分布在积聚模态,在0. 056～0. 56μm范围内有较高比例,OC3+OC4在粗模态的分布较为明显.Soot-EC浓度较低,没有明显的粒径分布特征,在0. 10～0. 18μm粒径段浓度较高,表明高温燃烧排放的EC主要分布在超细粒径段. Char-EC浓度远高于Soot-EC,在EC中占绝大部分比重.各主要碳组分在白天和夜晚的分布形态基本一致.夏季和冬季较有利于SOC的形成,OC/EC比值明显高于秋季. OC/EC值在不同粒径区间中差异很大,由于水溶性有机物(WSOC)主要分布在0. 056～0. 10μm,OC/EC值明显高于其他粒径段.白天及高温有利于气态有机物氧化生成SOC,致使夏季白天的OC/EC比值明显高于夜晚.各碳组分之间,EC1和OC1相关性最强,此外EC1和K+也有很强的相关性.     

微生物光电化学池去除硝酸盐氮:以PANI/TiO2-NTs为光阳极

利用微生物光电化学池(MPEC)去除污染物是一种经济高效环保的方法.本实验在制备获得聚苯胺/二氧化钛纳米管阵列(PANI/TiO_2-NTs)复合光电极的基础上,构建了由PANI/TiO_2-NTs光阳极和生物阴极组成的MPEC系统,并对其去除硝酸盐氮(NO~-_3-N)的性能进行研究.结果表明,PANI负载时间为80 s时,PANI/TiO_2-NTs电极光电性能最佳,相比于TiO_2-NTs电极光电流密度增大约一倍,PANI的修饰有效提高了光能利用率.构建的MPEC系统能在无外加电压的条件下利用光能驱动实现自养反硝化脱氮,NO~-_3-N的生物降解符合准一级反应动力学方程.光响应电流密度越大,系统反硝化脱氮性能越好,NO~-_3-N初始浓度为25 mg·L~(-1)时,当光响应电流密度从0.17 mA·cm~(-2)增加至0.67 mA·cm~(-2),平均反硝化速率从0.83 mg·(L·h)~(-1)增大到2.83 mg·(L·h)~(-1).对生物阴极微生物膜进行了高通量测序,发现Pseudomonas所占比例最大(27.37%)为优势菌属.分析认为PANI/TiO_2-NTs光阳极产生的光生电子通过外电路传递到阴极,Pseudomonas、Alishewanella和Flavobacterium等具有自养反硝化能力和电化学活性的微生物可直接利用电极上的电子作为唯一的电子供体进行自养反硝化脱氮.     

基于分区供氧与溶解氧调控的低C/N比污水短程硝化反硝化

针对城镇污水中碳源不足、C/N比低导致脱氮性能不佳的问题,建立了A2/O中试装置,通过调整系统缺氧/好氧分区比例及好氧区溶解氧水平,探究亚硝氮积累率及氮类污染物去除情况.结果表明,在DO为2. 0～2. 5 mg·L~(-1)条件下,改变缺氧/好氧分区比例对系统的影响较小,难以实现短程硝化;当控制DO为0. 5～0. 8 mg·L~(-1)、V_缺∶V_好=1∶1时为系统最优工况,此时系统好氧区末端亚硝氮积累率稳定在62%以上,出水总氮降至9. 0 mg·L~(-1),能够实现深度脱氮的目标.分析硝化菌表观活性可知,最优工况下SAOR与SNOR分别(以N/VSS计)为0. 14 g·(g·d)~(-1)和0. 04 g·(g·d)~(-1),二者差值较试验其他阶段更为明显,即NOB活性受到更高程度抑制是提高亚硝氮积累率的直接原因. Illumina MiSeq测序结果表明,该阶段NOB数量显著低于其他阶段.通过间歇OUR法分析缺氧区进出口碳源组成情况,结果表明最优工况下系统通过短程硝化节约碳源27. 3%,可生化性COD在缺氧区消耗63. 6%,远高于其他阶段,是低C/N比城市污水实现深度脱氮的碳源有力保障.