Interaction and influence of two creeks on Escherichia coli concentrations of nearby beaches: exploration of predictability and mechanisms

The impact of river outfalls on beach water quality depends on numerous interacting factors. The delivery of contaminants by multiple creeks greatly complicates understanding of the source contributions, especially when pollution might originate up- or down-coast of beaches. We studied two beaches along Lake Michigan that are located between two creek outfalls to determine the hydrometeorologic factors influencing near-shore microbiologic water quality and the relative impact of the creeks. The creeks continuously delivered water with high concentrations of Escherichia coli to Lake Michigan, and the direction of transport of these bacteria was affected by current direction. Current direction reversals were associated with elevated E. coli concentrations at Central Avenue beach. Rainfall, barometric pressure, wave height, wave period, and creek specific conductance were significantly related to E. coli concentration at the beaches and were the parameters used in predictive models that best described E. coli variation at the two beaches. Multiple inputs to numerous beaches complicates the analysis and understanding of the relative relationship of sources but affords opportunities for showing how these complex creek inputs might interact to yield collective or individual effects on beach water quality.     

Biofilm-overproducing Bacillus subtilis B12ΔYwcc decreases Cd uptake in Chinese cabbage through increasing Cd-immobilizing related gene abundance and root surface colonization

Biofilm-producing bacteria can decrease Cd uptake in vegetables, but mechanisms underlying this effect are poorly characterized. In this study, two mutant strains B12ΔYwcc and B12ΔSlrR were constructed from a biofilm-producing Bacillus subtilis strain B12. Then, the impacts of strain B12 and its high biofilm-producing mutant strain B12ΔYwcc and low biofilm-producing mutant strain B12ΔSlrR on Cd availability and uptake in Chinese cabbage and the related mechanisms were investigated in the Cd-polluted soil. Strain B12 and its mutants B12ΔYwcc and B12ΔSlrR increased the dry biomasses of edible tissues by 54%–130% compared with the controls. Strain B12 and its mutant B12ΔYwcc reduced the soil available Cd content by 36%–50% and root and edible tissue Cd contents by 23%–50% compared with the controls. Furthermore, the mutant strain B12ΔYwcc reduced the edible tissue Cd content by 40% and increased the polysaccharide content by 23%, invertase activity by 139%, and gene copies of the cumA by 4.5-fold, epsA by 7.1-fold, and cadA by 4.3-fold, which were involved in Cd adsorption in the rhizosphere soils, respectively, compared with strain B12. The polysaccharide content and cumA, epsA, and cadA gene copy numbers showed significantly reverse correlations with the available Cd content. Notably, the mutant strain B12ΔYwcc showed better ability to colonize the vegetable root surface than strain B12. These findings demonstrated that the biofilm-overproducing mutant strain B12ΔYwcc increased the polysaccharide production and Cd-immobilizing related cumA, epsA, and cadA gene copies, resulting in lower Cd availability and accumulation in Chinese cabbage in the Cd-polluted soil.     

废聚碳酸酯水解法制双酚A

以1,4-二氧六环为溶剂、NaOH为催化剂,采用废聚碳酸酯(PC)常压水解法制双酚A(BPA).对反应影响因素进行了研究.实验结果表明,在反应温度为100℃、反应时间为8h、m(NaOH):m(水+溶剂)=1:33、m(溶剂):m(PC)=4:1、m(水):m(PC)=1:1的最佳反应条件下,PC水解率大于98%,BPA收率大于95%.     

高效阿特拉津降解菌株DNS10降解条件优化

从长期施用阿特拉津的寒地黑土耕层(0～10 cm)土壤中筛选到一株能以除草剂阿特拉津为氮源生长的降解菌株,结合16S rRNA序列分析结果,将该菌株命名为Arthrobacter sp.DNS10。在接种量为108CFU/mL的条件下,菌株DNS10在24 h内对100 mg/L阿特拉津的降解率为99.41%。单因子实验结果表明,菌株DNS10适宜生长和降解的条件范围是:温度25～35℃,pH值5.0～8.0,培养液盐度0.1%～2%,对阿特拉津最大耐受浓度可达1 200 mg/L。正交实验法进一步表明,该菌株保持较好生长及降解能力的最优方案是温度30℃,pH值7.5,培养液盐度0.5%。影响其降解能力的环境因素的主次顺序依次是:温度>盐度>pH值。     

鄱阳湖湿地植物生态系统结构及湖水位对其影响研究

通过对鄱阳湖水文过程和湖盆地形特点的分析，利用3S技术对鄱阳湖湿地进行了分类，研究了各种类型湿地植物生态系统的生境、主要植物群落结构和分布规律。结果表明，鄱阳湖湿地植物生态系统结构复杂，生物多样性极其丰富。湿地植物是以根茎为主要繁殖器官的克隆繁殖植物，以集群分布为主要特点。在宏观尺度上受地形高程、湖水位和洲滩出露时间制约，不同植物群落沿水分梯度分布；在景观尺度上受到土壤含水量、地下水埋深和土壤结构影响，形成水平镶嵌结构；微观尺度上还与微地形和土壤养分密切相关，部分区域表现为复合体结构。湿地植被对水分梯度的敏感性，导致湿地植物生态系统的易变性和脆弱性。近年来，鄱阳湖水位过低且持续时间长，使生态系统遭受一定损害。     

板材类生物质燃烧及动力学特性热重研究

采用非等温升温法研究了4种板材类生物质在空气气氛下的燃烧特性和动力学特性。通过对TG、DTG等曲线的分析,发现4种板材燃烧过程均可分成3个阶段,即水分蒸发阶段、挥发份析出(或燃烧)阶段和固定碳燃烧阶段。综合燃烧特性:松木集成材>纤维密度板>夹芯胶合板>刨花板。4种板材均具有良好的燃烧特性。4种生物质燃烧均存在1个吸热峰和2个放热峰,分别与挥发分析出峰、挥发分燃烧、固定碳燃烧对应。采用Fridman法和Fridman-Carroll法分别对4种板材的动力学参数进行了计算,2种方法得出的结果符合较好。分析得出:由于生物质燃烧与环境换热、挥发分析出吸热、固定碳燃烧放热等因素作用,4种生物质的表观活化能高温区均低于低温区。动力学计算结果表明:松木集成材平均表观活化能最低,燃烧反应能较容易进行。     

Kinetics of the gas-phase reactions of NO3 radicals with ethyl acrylate,n-butyl acrylate,methyl methacrylate and ethyl methacrylate

The relative rate method has been used to determine the rate constants for the gas-phase reactions of NO₃ radicals with a series of acrylate esters: ethyl acrylate (k₁), n-butyl acrylate (k₂), methyl methacrylate (k₃) and ethyl methacrylate (k₄) at 298 ± 1 K and 760 Torr. The obtained rate constants are k₁ = (1.8 ± 0.25) × 10^?16 cm³ molecule^?1 s^?1, k₂ = (2.1 ± 0.33) × 10^?16 cm³ molecule^?1 s^?1, k₃ = (3.6 ± 1.2) × 10^?15 cm³ molecule^?1 s^?1, k₄ = (4.9 ± 1.7) × 10^?15 cm³ molecule^?1 s^?1. The experimental rate constants are in good agreement with theoretical rate constants calculated by an algorithm of the correlation between the rate constants and the orbital energies for the reactions of unsaturated VOCs with NO₃ radicals. In addition, the atmospheric lifetimes of the compound against NO₃ attack are estimated and the results show that NO₃ reactions contribute little to the atmospheric losses of acrylate esters except in polluted regions.     

自然灾害社会脆弱性评估研究——以上海市为例

基于投影寻踪聚类模型(PPC),结合基于实数编码的加速遗传算法(RAGA),对上海市进行了自然灾害社会脆弱性评估的尝试。结果表明:①灾害社会脆弱性最高的为崇明县,其次为宝山区和金山区;②灾害社会脆弱性最低的是黄埔区,其次是徐汇区和静安区;③总体而言,灾害脆弱性较低的地区集中于上海城市中心区,而城市边缘区的社会脆弱性一般较高。