Simulating the impacts of land-use changes on non-point source pollution in Lugu Lake watershed

Protection of the water quality of Lugu Lake is important because it is a unique geographic and cultural resource. Not only point source pollution but also non-point source pollution contribute to degradation of water quality. A GIS-NPS model, with long-term hydrologic impact assessment (L-THIA), was used to evaluate long-term implications of land-use change impacts on non-point source (NPS) pollution. The land-use patterns of 1995 and 2005 were analysed to determine the changes in Lugu Lake watershed. A 30-year (1974–2003) precipitation dataset was used to estimate mean annual surface runoff and NPS pollutant loads. The contributions of different land-use categories to average annual runoff and NPS pollutant production were assessed with a unit contribution index (UCI). Results show loss of agricultural land (by 44.9%), while forest, grass/pasture and residential land increased to different degrees from 1995 to 2005. At the same time, annual average NPS pollutants, TN, TP, TSS and BOD loads all decreased, while heavy metal lead increased by 6.87%. The UCI formulated in this research was a more useful method to assess land-use impact on NPS pollutants than simple investigations of the percentage land-use change. Agricultural and residential land changes had more impact on NPS pollutants and were identified as the main source types. Suggestions on regulating land uses and management proposals for protecting lake water quality in Lugu Lake watershed are made.     

Terrestrial laserscanning of tidal flats—a case study in Jiangsu Province, China

Terrestrial laserscanning (TLS), also called ground-based LiDAR (Light Detection And Ranging) is a relatively new method which revolutionised geomorphological research in many domains. However, detailed studies of tidal flats by TLS have not been described in the literature yet. This study aims to fill this methodological gap by the application of TLS at two different locations on the coast of Jiangsu Province, Eastern China, and an assessment of the usability of this method for geomorphological research in such environments. The acquired point clouds are first processed to remove erroneous and noisy points. Subsequently, point clouds are computed to produce polygonal meshes and grid-based digital terrain model (DTM) more commonly used by the scientific community. The accuracy of the measurements is assessed by an analysis of elevation deviations for flat and horizontal concrete blocks. High quality point clouds with point densities of up to 4,000 points/m² were acquired for a distance of up to 200 m. The data allowed for the detection of small landforms such as tidal channels, creeks and ripples in centimetre and decimetre scale. The point clouds had an average error of approximately 3 mm, however for some few points errors of up to 1.8 cm were detected. Based on the results it can be concluded that TLS can be a useful additional method for geomorphological research on tidal flats due to its ability to describe the landforms from high density point clouds. Repeated scanning could therefore provide data to quantitatively and qualitatively describe geomorphological changes over wider areas and thereby improve the understanding of sedimentation and erosion on tidal flats.     

广西桂林人工增雨抗旱作业方案设计

为切实发挥人工增雨在抗旱工作中的作用,保证人工增雨作业能发挥最大效益,对桂林市多年来的人工增雨作业方式、作业效果进行了分析;分别对各季节、各作业云系的作业记录进行了归类;对成功和失败的作业方式进行了总结。参考国内其他比较成功的人工增雨作业经验,分别提出了适合桂林地区不同季节的人工增雨作业方案。     

辽东湾大凌河口湿地土壤微生物群落分析

土壤微生物对湿地生态系统的物质转化和能量流动具有重要作用,目前对天然湿地的微生物资源及群落结构缺少研究。应用PCR-DGGE技术研究辽东湾大凌河口湿地土壤中的微生物群落结构,并对其群落组成进行分析,结合冗余分析（RDA）方法考察环境因子对微生物群落结构的影响。共设定7个站位采集土壤样品,直接提取样品中微生物的总DNA,以巢式PCR扩增细菌16S rDNA-V3区片段,应用变性梯度凝胶电泳（DGGE）技术分离片段,研究河口区湿地土壤细菌的群落结构。结果表明：辽东湾大凌河口区土壤具有较为丰富的细菌种群,主要包含Proteobacteria、Actinobacteria和Bacteroidetes几大类门,且同一季节采集的样品在聚类分析图上聚类成簇。RDA分析表明,土壤的温度与盐度2个变量分别解释了6.5%、2.3%的土壤细菌群落结构变化,表明大凌河口区土壤的群落结构变化是多种环境因子共同作用的结果,其中温度的影响略大于盐度。     

In situ enhanced bioremediation of dichlorvos by a phyllosphere Flavobacterium strain

A bacterium capable of degrading dichlorvos was isolated from the rape phyllosphere and designated YD4. The strain was identified as Flavobacterium sp., based on its phenotypic features and 16S rRNA gene sequence. Strain YD4 was able to utilize dichlorvos as the sole source of phosphorus. In situ enhanced bioremediation of dichlorvos by YD4 was hereafter studied. Chlorpyrifos and phoxim could also be degraded by this strain as the sole phosphorus source. A higher degradation rate of dichlorvos was observed after spraying YD4 onto the surface of rape leaves when compared to the sterilized-YD4 and water-treated samples. The results indicated that pesticide-degrading epiphytic bacterium could become a new way for in situ phyllosphere bioremediation where the hostile niche is unsuitable for other pesticide-degrading bacteria isolated from soil and water.     

洛克沙胂暴露胁迫对土壤微生物群落结构特征的影响

采用磷脂脂肪酸(phospholipid fatty acid,PLFA)方法,分析了洛克沙胂残留对土壤微生物群落结构的影响特征。结果表明,在整个采样周期中,每克土壤总PLFA含量在洛克沙胂胁迫影响下出现明显降低,且存在一定的剂量依赖效应。经主成分分析,第1周,洛克沙胂低浓度组(w=15 mg·kg-1)土壤微生物群落结构和对照组差异不明显,第2、3、5、8周,各组土壤微生物群落结构多样性的类型差异显著,其中高浓度组(w=150 mg·kg-1)与对照组差异最大。结果表明,洛克沙胂可致土壤微生物群落结构多样性改变,暴露浓度越高其作用越强。同时,洛克沙胂对土壤微生物群落结构多样性的影响还表现出时间差异,在暴露胁迫的后期(第5、8周),洛克沙胂的影响逐步减弱,可能与洛克沙胂在土壤中发生化学结构改变和降解有关。     

赤泥酸浸出铁、铝的工艺条件研究及其表征

对广西某铝厂的赤泥进行了盐酸浸出铁、铝的工艺条件研究,并利用扫描电镜和X－衍射对赤泥酸溶前后的形貌特征及矿物物像、化学成分进行分析表征,研究结果表明,赤泥在温度为80℃、液固比为6、浓度为7 mol／L的盐酸中反应3 h ,Fe和Al的浸出率分别为82％和30．5％;酸溶前后赤泥形貌由团粒状转变为层架状,赤泥中赤铁矿矿物相被盐酸充分溶出。     

Effect of protein on PVDF ultrafiltration membrane fouling behavior under different pH conditions: interface adhesion force and XDLVO theory analysis

To further determine the fouling behavior of bovine serum albumin (BSA) on different hydrophilic PVDF ultrafiltration (UF) membranes over a range of pH values, self-made atomic force microscopy (AFM) colloidal probes were used to detect the adhesion forces of membrane–BSA and BSA–BSA, respectively. Results showed that the membrane–BSA adhesion interaction was stronger than the BSA–BSA adhesion interaction, and the adhesion force between BSA–BSA-fouled PVDF/PVA membranes was similar to that between BSA–BSA-fouled PVDF/PVP membranes, which indicated that the fouling was mainly caused by the adhesion interaction between membrane and BSA. At the same pH condition, the PVDF/PVA membrane–BSA adhesion force was smaller than that of PVDF/ PVP membrane–BSA, which illustrated that the more hydrophilic the membrane was, the better antifouling ability it had. The extended Derjaguin–Landau–Verwey–Overbeek (XDLVO) theory predicts that the polar or Lewis acid–base (AB) interaction played a dominant role in the interfacial free energy of membrane–BSA and BSA–BSA that can be affected by pH. For the same membrane, the pH values of a BSA solution can have a significant impact on the process of membrane fouling by changing the AB component of free energy.

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Screening of the marine actinomycetes with anti-complement activity and isolation of the active fractions北大核心CSCD

Studies on anti-complement agents are essential for the development of drugs to treat various diseases caused by excessive or abnormal activation of the complement system. However, studies on microbial-derived anti-complement agents are still very limited. The anti-complement activities of 42 marine-derived actinomycete strains isolated from the sediment samples collected from Xinghai Bay in Dalian were studied using the hemolysis method. In addition, the active fractions of the strain Streptomyces sp. DUT11 were separated by C18 and Sephadex LH-20 column chromatography, and the active compounds with anti-complement activity were identified. Streptomyces strains S187, M5, S088, M8, S063, DUT11 and MD16 showed good anti-complement activities upon being cultured in TSB medium, with the strain DUT11 showing the best anti-complement activity among these strains. When different fermentation media were tested, the highest anti-complement activity of DUT11 was observed in M33 fermentation medium. The anti-complement activity was 56.5% for the extract of supernatant and 60.8% for the extract of mycelia, respectively. Furthermore, three compounds with anti-complement activity were obtained from the active components, which were identified as 3-indolecarboxylic acid (1), p-hydroxy benzoic acid (2) and 2-pyrrolecarboxylic acid (3). These results demonstrated that marine-derived streptomycetes can be employed to produce active compounds with anti-complement activity. This study presents a new alternative for the utilization of marine actinomycetes and provides a basis for the exploration of new anti-complement agents. © 2018 Science Press. All rights reserved.     

滏阳河河流水体中重金属污染特征及其对青海弧菌和斜生栅藻的毒性效应

为调查滏阳河水系的重金属污染状况,研究河流重金属污染对水生生物的毒性,根据河流结构、水文条件、排污口分布并考虑空间分布的均匀性,选取66个采样位点,采集河水及对应的表层沉积物样品,分析了样品中的重金属含量。用斜生栅藻和青海弧菌Q67作为模式生物,根据滏阳河水重金属污染较严重的邯郸近郊2号采样点采集水样的重金属含量配制系列重金属浓度的模拟河水进行重金属污染河水的生态毒性测试。结果表明,在全部66个采样点中,29个采样点河水重金属含量超过国家地表水III类水体重金属含量标准,主要污染元素是Hg、Pb、Cr、Zn。几乎所有采样点河水Mn和Fe含量都大大高于国家集中式生活饮用水地表水源地补充项目规定的标准限值。根据2号采样点河水样品中的重金属含量配成的模拟河水对青海弧菌Q67的EC_(50)值为6.65%,为毒性极强的污染物。模拟河水样品对斜生栅藻的抑制作用较小,在实验的最高浓度下(1 000倍河水重金属含量)暴露4 d尚未引起半数藻细胞死亡。随河水重金属浓度上升,斜生栅藻超氧化物歧化酶(SOD)活性总体上呈现先升高后降低的趋势,丙二醛(MDA)含量变化则与此相反,反映河水重金属污染可引起藻细胞的氧化损伤。叶绿素a和b含量则随暴露浓度的提高逐渐降低。在重金属浓度达到2号采样点河水的10%时,斜生栅藻叶绿素a含量已有显著降低,MDA含量显著升高,海河流域重金属污染对生态系统的影响应予以重视。河水发光菌Q67的生长抑制率、斜生栅藻的叶绿素a和MDA含量可以作为评估河流重金属污染生态危害的指标。