微生物电容脱盐燃料电池性能研究

以微生物电容脱盐燃料电池(MCDC)为研究对象,考察了反应时间、盐溶液浓度和电容电极对数对MCDC脱盐效率的影响.试验采用阳离子交换膜分隔阳极室与脱盐室,阴离子交换膜分隔阴极室与脱盐室.试验结果显示在处理5 g·L-1的NaCl溶液试验中,脱盐室溶液盐度先降低后升高,在反应运行30 min时,脱盐室达到最大脱盐率47.83%.同时发现在脱盐过程中,阳极室和阴极室溶液盐度持续降低,运行150 min后分别下降到15.24%和6.12%.随盐溶液浓度的增加,脱盐率降低,单位电极吸附量增加,根据Langmuir方程和Freundlich方程的线性拟合得到,MCDC最大脱盐吸附容量为72.99 mg·g-1,电容吸附为复杂度的双分子层吸附.电极对数从1对增加到4对,MCDC的脱盐效率提高了37.37%.通过电容电极反接,可在1 h内实现电容再生.     

江汉平原农田土壤有机碳分布与变化特点:以潜江市为例

以地处江汉平原腹地的潜江市农田土壤(水田、旱地)为研究对象,于2011年实地采样分析表层土壤(0~20 cm)有机碳的分布现状,并对比第二次土壤普查(1983年)资料,探讨28 a来江汉平原农田土壤有机碳的分布与变化特点.结果表明,2011年潜江市农田表层土壤有机碳密度为30.50 t·hm-2,碳储量为452.82×104t,与1983年相比有明显下降,下降速率分别为0.10 t·(hm2·a)-1和1.53 t·a-1,碳储量共损失了9%.两个时期水田土壤有机碳密度均明显高于旱地土壤,分别是旱地土壤的1.6倍和1.3倍,但是经过28年的常规耕作管理,水田土壤有机碳密度呈下降趋势,下降速率为0.23 t·(hm2·a)-1,导致的有机碳损失为52.83×104t,损失比例达16%;而旱地土壤有机碳则以0.05 t·(hm2·a)-1的速率缓慢增长,碳储量共增加了8.57×104t,增加比例为5%,远不能抵消水田土壤的有机碳损失.水田土壤碳储量的损失主要来自于低产潜育型水稻土碳密度的大幅下降所致(尽管其所占面积比例较小),其碳损失量占水田碳损失量的比例达80%;其次为占水田面积比例最大的潴育型水稻土,其碳损失量占水田碳损失量的15%.旱地土壤碳储量增长缓慢,完全来自于面积占96%的灰潮土有机碳密度的增长.因此,江汉平原区水田土壤有机碳的变化决定了农田土壤有机碳的整体动向,今后需着力提升有机碳下降迅速的低产水田以及面积较大的土壤类型的有机碳积累和固持能力.     

南京夏季城市冠层大气 CO2浓度时空分布规律的观测

城市是CO2重要排放源,直接观测城市中大气CO2浓度对于研究人类活动对大气温室气体的贡献至关重要,而在城市中多个站点、多个高度上观测大气CO2浓度则有助于认识城市CO2浓度的时空变化规律,确定其影响机制.本研究于2014年7月18日至7月25日在南京主城区东、西、南、北和中共5个方位(100 m左右高度),2014年8月3日至2014年8月9日在南京主城区中部站点的3个高度(30、65和110 m)观测CO2浓度.结果表明:1南京主城区垂直方向上CO2浓度存在明显梯度,近地面30 m处CO2浓度受人为活动影响明显,平均值达427.3×10-6(±18.2×10-6)(摩尔分数,下同),高层65m、110 m处CO2浓度混合均匀,平均值分别为411.8×10-6(±15.0×10-6)和410.9×10-6(±14.6×10-6).大气层结越稳定,CO2浓度越高,垂直梯度越大.2南京主城区CO2浓度的水平分布受风和大气稳定度的控制.观测期间盛行东北风向,导致CO2浓度分布整体呈现西南高,东北低的格局,城市主城区上下风向CO2浓度差为7.8×10-6.而且水平风速越大,越有助于将上风向的CO2传输至城市的下风向,CO2浓度差就越小.大气层结越稳定,整体CO2浓度越高.3南京主城区5个站点CO2浓度均有明显的日变化,日最高值出现在交通早高峰期间,谷值在17:00左右,在19:00左右有时会因交通晚高峰而出现次高值.     

Characterization and prediction of highway runoff constituent event mean concentration

Highway stormwater runoff quality data were collected from throughout California during 2000-2003. Samples were analyzed for conventional pollutants (pH, conductivity, hardness, and temperature); aggregates (TSS, TDS, TOC, DOC); total and dissolved metals (As, Cd, Cr, Cu, Ni, Pb, and Zn); and nutrients (NO(3)-N, TKN, total P, and ortho-P). Storm event and site characteristics for each sampling site were recorded. A statistical summary for chemical characteristics of highway runoff is provided based on statewide urban and non-urban highways. Constituent event mean concentrations (EMCs) were generally higher in urban highways than in non-urban highways. The chemical characteristics of highway runoff in California were compared with national highway runoff chemical characterization data. The results obtained in California were generally similar to those found in other states. The median EMC for Pb measured in studies conducted in previous decades was much higher than the current median Pb EMC in California. The lower Pb EMC in California compared to previous highway runoff monitoring is believed to be due to the elimination of leaded gasoline. An attempt was also made to identify surrogate constituents within a general family of water quality categories using Spearman correlations and selected pairs with Spearman coefficients greater than 0.8. The strongest correlations were observed among parameters associated with dissolved minerals (EC, TDS, and chloride); organic carbon (TOC and DOC); petroleum hydrocarbons (TPH and O & G); and particulate matter (TSS and turbidity). Within the metals category, total iron concentration was highly correlated with most total metal concentrations. The correlations between total and dissolved concentrations were all less than 0.8, even between total and dissolved concentrations of the same metals. Multiple linear regression (MLR) analyses were performed to evaluate the impact of various site and storm event variables on highway runoff constituent EMCs. Parameters found to have significant impacts on highway runoff constituent EMCs include: total event rainfall (TER); cumulative seasonal rainfall (CSR); antecedent dry period (ADP); contributing drainage area (DA); and annual average daily traffic (AADT). Surrounding land use and geographic regions were also determined to have a significant impact on runoff quality. The MLR model was also used to predict constituent EMCs. Model performance determined by comparing predicted and measured values showed good agreement for most constituents.     

大牛地气田污水预处理药剂加量研究

大牛地气田污水水质总体呈现高浊度、高矿化度、高腐蚀性、高含铁量及低pH值"四高一低"的特点。预处理阶段对后续处理过程起着重要的作用,试验确定了该阶段的加药量,提出了"一控二适量"的加药原则,选定JH-1、JH-2、JH-3的加量分别为300、50和2mg/L配合使用,使污水pH值控制在8.0～8.4之间,既节省了运行费用,又极大地缓解了处理过程中设备的结垢堵塞现象。     

污水厂污泥在不同氧气浓度下的热分析动力学特性研究

为了解在不同氧气浓度下污泥的热解燃烧行为和动力学机理,利用热重差热分析仪,在不同氧气浓度下,对经过不同干燥温度干燥的污泥样品进行热重差热实验.通过分析氧气浓度和干燥温度对样品热分析曲线的影响发现,干燥温度对污泥样品热分析的影响很小,但氧气浓度对其有明显的影响;随着氧气浓度的增加,热分析曲线有规律的向左偏移.在此基础上,提出污泥在不同氧气浓度条件下3种物质独立反应的热化学反应动力学模型.在该模型中,3个阶段分别对应3种不同的物质独立反应.在各种氧气浓度条件下,这3种物质的反应过程均符合一级反应模型.随着氧气浓度的上升,3个阶段对应的活化能和频率因子呈现上升趋势.     

固定化曝气生物滤池处理采油废水

采用一种特殊载体固定复合微生物B350M在曝气生物滤池反应系统中处理采油废水.废水中的盐度>0.5%,N、P营养缺乏,有机物浓度较低.在HRT为4h、COD容积负荷为1.07 kg/(m³·d)的条件下,小试反应装置稳定运行142d,处理效果良好,石油类、TOC、COD和H₂S的平均降解效率分别达到90.5%、74.4%、85.6%和100%.GC-MS分析表明,进水中含有机物27种,其中烷烃类23种,芳烃类4种.此反应系统可以将大分子量烷烃类物质(C₁₈H₃₈至C₂₈H₅₈),尤其是其中的支链烷烃切碎形成小分子量物质,并有效地处理菲等多环芳烃.反应系统中,生态多样性丰富,载体为微生物提供了良好的水、气环境,抵御盐度、有机污染物的毒害作用,并可以固定丝状菌,因而避免出现污泥膨胀,出水SS过高等影响出水水质的情况.     

垃圾焚烧飞灰基本性质的研究

分析了几种焚烧飞灰的基本性质,讨论了燃烧过程中可能影响飞灰中重金属分布的因素,研究表明:焚烧飞灰结构复杂性和性质多变,其主要的化学组成为Cl、Ca、K、Na、Si、Al、O等,主要的重金属为Zn、Pb、Cr、Cu等;飞灰多以不规则的无定形态和多晶聚合体的结构存在,浸出毒性一般超过危险废物鉴别标准;重金属主要以气溶胶小颗粒和富集于飞灰颗粒表面的形式存在于飞灰中.焚烧厂和焚烧时间的变化对于飞灰性质有较大影响,几种飞灰的Cl含量范围为6.93%～29.18%,SiO₂为4.48%～24.84%;浸出毒性则在0～163.10mg·L^-1(Pb)、0.049～164.90mg·L^-1(Zn)之间变化.     

Preliminary study on health risk from mercury exposure to residents of Wujiazhan town on the Di’er Songhua river, Northeast China

Mercury concentrations in hair are typically used as a biomarker to assess exposure to mercury. A total of 108 hair samples were collected from residents (age range 5–73 years) of Wujiazhan town, northeast China, to determine total mercury concentrations. Hair mercury concentrations ranged from 0.16 to 199 mg kg^–1 with an average value of 3.41 mg kg⁻¹. The relationships between mercury concentration and gender and between hair mercury concentration and age were not significant. Overall, 16.7% of all samples were above the RfD value published by the United States Environmental Protection agency. The results indicate that there may be some been health risk from mercury exposure to the residents in the study area.     

Isolation of culturable mycobiota from agricultural soils and determination of tolerance to glyphosate of nontoxigenic Aspergillus section Flavi strains

Glyphosate-based herbicides are extensively used in Argentina's agricultural system to control undesirable weeds. This study was conducted to evaluate the culturable mycobiota [colony forming units (CFU) g^?1 and frequency of fungal genera or species] from an agricultural field exposed to pesticides. In addition, we evaluated the tolerance of A. oryzae and nontoxigenic A. flavus strains to high concentrations (100 to 500 mM – 17,000 to 84,500 ppm) of a glyphosate commercial formulation. The analysis of the mycobiota showed that the frequency of the main fungal genera varied according to the analyzed sampling period. Aspergillus spp. or Aspergillus section Flavi strains were isolated from 20 to 100% of the soil samples. Sterilia spp. were also observed throughout the sampling (50 to 100%). Aspergillus section Flavi tolerance assays showed that all of the tested strains were able to develop at the highest glyphosate concentration tested regardless of the water availability conditions. In general, significant reductions in growth rates were observed with increasing concentrations of the herbicide. However, a complete inhibition of fungal growth was not observed with the concentrations assayed. This study contributes to the knowledge of culturable mycobiota from agricultural soils exposed to pesticides and provides evidence on the effective growth ability of A. oryzae and nontoxigenic A. flavus strains exposed to high glyphosate concentrations in vitro.