基于致灾因子指标体系的海冰灾害风险评估和区划方法

中国是世界上受海冰危害严重的国家之一,历史上曾发生过多次严重海冰灾害,造成重大损失。根据我国结冰海区海冰灾害风险的自然过程、社会经济状况和成灾机制,综合考虑致灾因子危险性、承灾体分类、分布及脆弱性以及防灾减灾能力等因素,对海冰灾害发生的可能性及其不确定性等进行综合分析,提出了开展海冰灾害风险评估和区划的理论依据,同时给出了利用致灾因子指标体系对海冰灾害风险进行评估和区划的具体方法。     

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.     

确定性系数与地理探测器模型耦合的泥石流易发性评估方法研究∗——以安宁河流域为例

通过确定性系数与地理探测器模型耦合的方法研究耦合模型对泥石流灾害易发性评估的影响。基于遥感判识和野外考察确定安宁河流域内的 198 条泥石流沟作为评估样本,选取坡度、地面峰值加速度、地形起伏度、地层岩性、植被覆盖度、植被类型、地形湿度指数以及地貌演化指数作为评价因子,耦合确定性系数和地理探测器模型,分别计算各评价因子分级取值和因子权重,进行安宁河流域泥石流易发性等级分区。研究结果表明：(1)地理探测器方法定量分析安宁河流域内泥石流发育的主要贡献因子为地面峰值加速度、地形起伏度和坡度。(2)泥石流极高易发区和高易发区分别占流域总面积的 9.67% 和 12.02%,高易发区主要分布在安宁河流域两岸且呈条带状分布。 (3)利用 ROC 曲线对泥石流易发性评估精度进行验证,耦合模型的 AUC 值达到 0.824,相比单种模型 CF 模型的评估精度 0.786 提升了 4.8%,具有更高的准确率,评价效果更优。     

饮食业污水排污费征收办法的研究

在分析了当前饮食业排污收费现状和存在问题的基础上，提出了一种较易操作的排污费征收办法，并认为这种征收办法在实践上是可行的。     

袋式除尘器进气均布板结构参数对气流分布的影响分析

针对袋式除尘器的进气均布板主要结构参数对气流分布影响的问题,采用正交试验方法进行CFD模拟试验设计,并以气流速度相对均方根σ值作为气流均匀性的评价指标。研究结果给出了σ与板数n、板长L、挡板上端距灰斗顶部截面高度ΔH、挡板前后偏角θ及过滤风速v之间的函数关系式。表明适当增加n、增大ΔH和θ、减小L、降低v,可以提高进气流分布均匀程度,影响进气均匀分布程度的排序为L>θ>n>ΔH>ΔL。     

浅海跃层底质对水下声的影响研究

本文针对海底底质对水下噪声传播具有显著影响的现象,选取典型负梯度温度跃层,加载三个典型海底底质,即细砂底质、粉砂底质及黏土-粉砂底质,声波参数为固定值。试验定性分析了浅海海底底质对水下声传播的影响,仿真计算了海底底质对声传播的影响,比较分析了不同底质条件下声波的衰减差异,总结了不同底质对水下声传播影响的特点,并同行参考。     

金沙江丰富类和稀有类浮游真核微生物的分布特征与影响因素

浮游真核微生物通常由少数丰富类和大量稀有类组成,二者在维持水生生态系统健康稳定方面具有重要作用.目前对大型筑坝河流中这两类真核微生物的生物地理分布模式所知甚少.以我国西南梯级水电开发河流金沙江为研究区域,对比分析丰富类和稀有类浮游真核微生物在不同河段的分布特征,解析影响两类微生物空间分布的主导因素.结果表明,相比上游自然河段,金沙江浮游真核微生物的α多样性在梯级大坝河段显著升高,稀有类的α多样性增长比高于丰富类.浮游真核丰富类和稀有类微生物的群落组成在不同河段间存在显著差异,其中Vermamoeba属等优势属的相对丰度在两河段间同样存在明显差异.影响丰富类和稀有类浮游真核微生物群落组成的关键地化因子有海拔和pH等,两类微生物群落相似性与地理距离和环境异质性均符合距离衰减关系,其群落构建均受扩散限制和环境筛选共同影响;方差分解分析和偏Mantel检验结果显示扩散限制是影响丰富类和稀有类分布的主要驱动因素.研究结果为我国西南缺资料区水电开发河流中微生物的地理分布模式和生态响应提供数据支持.