NirS-type denitrifying bacteria in aerobic water layers of two drinking water reservoirs: Insights into the abundance, community diversity and co-existence model

The nirS-type denitrifying bacterial community is the main drivers of the nitrogen loss process in drinking water reservoir ecosystems.The temporal patterns in nirS gene abundance and nirS-type denitrifying bacterial community harbored in aerobic water layers of drinking water reservoirs have not been studied well.In this study,quantitative polymerase chain reaction (qPCR) and Illumina Miseq sequencing were employed to explore the nirS gene abundance and denitrifying bacterial community structur...     

澜沧江流域梯级水库建设下水体营养盐和叶绿素a的空间分布特征

澜沧江梯级水库群建设对流域水生态环境产生了一定的影响,将流域水体划分为自然河道段和水库段.为了探究梯级水库建设后澜沧江流域不同类型水体氮、磷营养盐和叶绿素a浓度的空间变化规律以及叶绿素a浓度与环境因子之间的关系,于2017年6月对澜沧江流域生态环境进行了调查分析.结果表明,澜沧江水体总氮质量浓度变化范围为0.37~1.22 mg·L^-1,均值为0.70 mg·L^-1;总磷质量浓度变化范围0.01~0.19 mg·L^-1,均值为0.04 mg·L^-1.单因素ANOVA分析表明,总氮空间差异显著,表现为支流段 > 水库段 > 自然河道段;但总磷没有明显的空间差异.澜沧江水库段水体叶绿素a浓度变化范围为2.6~10.2μg·L^-1,均值为5.8μg·L^-1.Pearson相关性分析结果显示,水体叶绿素a浓度与总磷浓度、水温和真光层与混合层之比（Z_eu/Z_mix）等具有显著相关性,其中与Z_eu/Z_mix的相关性最高（R²=0.689,P=0.001）,表明水温分层驱动下的Z_eu/Z_mix是影响澜沧江水库水体中浮游植物生长的关键性指标.     

CHARACTERIZATION OF INORGANIC PARTICLES IN SELECTED RESERVOIRS AND TRIBUTARIES OF THE NEW YORK CITY WATER SUPPLY1

ABSTRACT: Individual particle analysis (IPA) by scanning electron microscopy interfaced with automated image and X‐ray analyses was used to characterize inorganic particles in five reservoirs and four tributaries located within the Catskill and Delaware systems of the New York City water supply. Individual particle analysis provides combined elemental and morphologic characterizations. Results are presented in terms of particle projected area per unit volume (PAV), consistent with optical impacts, and partitioned into seven generic particle types according to composition. Minerals of terrigenous origins, particularly clay minerals, dominated the inorganic particle populations of all the study systems except one downstream reservoir. Higher PAV levels were observed in the Catskill system. Particle dynamics represented by PAV were driven primarily by runoff, while the reservoirs were also greatly influenced by the timing of sediment resuspension promoted by drawdown of the surface and fall mixing. The benefit of the serial configuration of the reservoirs in decreasing inorganic particles with progression downstream towards the city is demonstrated. The patterns in PAV levels among the study systems generally tracked those of more common metrics of impacts of suspensoids, including mass concentrations of suspended solids, turbidity, and Secchi disc transparency.     

挥发性油藏回注气井控因素分析及措施

文章明确了挥发性油藏天然气回注井控的安全环保关键因素;量化了低渗挥发性油藏天然气回注注入能力,确定注入端各节点安全生产压力分布,攻关相关配套工艺设备,实现安全有效注入;开展室内实验和PVT相态拟合,分析注天然气后天然气和原油性质变化规律,创新非混相驱组分数值模拟参数优化方法,开展带人工压裂裂缝的组分数值模拟,精准确定压力场分布,降低计量及监测不准带来的安全隐患;明确注气井气窜影响因素,优化注采参数,抑制油井气窜,降低生产风险,实现井控安全情况下的天然气驱环保高效开发。     

河北水库及湖泊沉积物中DDT农药的残留特征与风险评估

分析了河北省主要湖泊水库沉积物中有机氯农药(DDT)的残留特征与生态风险.2004年秋季采集了河北12个水库和2个湖泊的表层沉积物样品,利用GC-ECD测定DDTs农药的含量,在此基础上分析了其残留与组成特征以及生态风险.结果表明:1)河北省主要湖泊水库沉积物中DDTs的平均含量为3.328 ng·g-1,其含量范围为1.014～9.022 ng·g-1;并且,不同样品中DDTs的含量的差异较大,变异系数均超过65%.2)临城水库、陡河水库、龙门水库3个样点的表面沉积物中wDDT/(wDDD wDDE)＞1,表明有新的DDT输入;岗南水库、邱庄水库、黄壁庄水库3个样点的表面沉积物中wDDD/wDDE＞1,说明DDD降解环境为厌氧条件;其余8个样点wDDD/wDDE＜1,说明DDD降解环境为好氧条件.3)所有样点中DDT、DDD和DDE浓度均低于ERM,并且大部分小于ERL,表明其生态风险大多低于10%;但11个样点的DDTs含量介于ERL和ERM之间,表明其生态风险大多介于10%～50%.     

典型喀斯特城市湖库溶解性有机质成分特征及来源解析

为探索喀斯特城市湖库溶解性有机质（DOM）成分特征及来源信息,以我国贵阳市重要喀斯特湖库——红枫湖、百花湖、松柏山水库和阿哈水库为研究对象,分析了表层水体溶解性有机碳（DOC）、叶绿素a（Chla）和DOM光学参数(a₂₅₄、a₂₈₀、a₃₅₀、 E2∶E3、S_275-295、 FI、β:α、 BIX、 HIX)的空间差异,同时利用荧光吸收峰（B、 T、 A、 M、 C、 D、 N）和三维荧光平行因子分析（EEM-PARAFAC）解释DOM各成分丰度及占比状况,并运用Spearman相关分析及主成分分析（PCA）揭示DOM参数的相关性和主要环境过程.结果表明,喀斯特城市湖库ρ（DOC）和ρ（Chla）范围分别为4.24～11.9 mg·L^-1和0.32～19.7μg·L^-1,松柏山水库腐殖质(a₂₅₄)和芳香类蛋白质(a₂₈₀)较高,导致相对分子质量(E2∶E3和S_275-295)高于其它湖...     

澜沧江梯级水库对汞输运的影响

拦河筑坝对河流中汞的输运产生重要影响,但有关高海拔落差河流中汞的来源及输运特征的认识较为匮乏.以澜沧江为研究对象,监测了筑坝河段水体中汞浓度的年时空变化过程（2017—2018）,量化了梯级水库对汞沿程输运的影响.结果表明,澜沧江水体中汞浓度总体与径流的季节分配呈同步变化趋势,但在上下游因土地利用类型的差异而呈现相反的季节性变化特征.因水库的拦截,溶解态汞与总汞的比值沿程呈上升趋势,加之水库泄水量的沿程增加,共同导致了河流汞通量自上游至下游呈非连续累积的趋势,从144 kg·a^-1增加至788 kg·a^-1.相应地,梯级水库对汞的拦截率自上游至下游由88%逐渐降低至65%.该项研究丰富了对梯级水库中汞的补给和输运的认识.     

白石水库颗粒有机物及沉积物中碳、氮稳定同位素的空间分布特征

于2013年10月对辽宁省白石水库水质、颗粒有机物及底泥沉积物中δ~(13)C和δ~(15)N值的空间分布特征进行了研究.结果表明:白石水库POC的平均浓度为(1.76±0.98)mg·L~(-1);TP的平均浓度为(0.04±0.03)mg·L~(-1);TN的平均浓度为(1.80±0.08)mg·L~(-1),TP和POC从上游到下游呈现逐渐降低的趋势;TN的水平分布变化不大.小型颗粒有机物的δ~(13)C值平均为(-24.6±0.9)‰;δ~(15)N值平均为(4.8±0.4)‰.大型颗粒有机物的δ~(13)C值平均为(-22.5±0.9)‰;δ~(15)N值平均为(6.7±0.5)‰,颗粒有机物的δ~(13)C和δ~(15)N变化范围都很广,小型颗粒有机物的δ~(13)C和δ~(15)N值最大差异可达4.6‰和2.7‰,大型颗粒有机物的δ~(13)C和δ~(15)N值最大差异分别为3.3‰和1.8‰.底泥沉积物的δ~(13)C值平均为(-24.2±1.2)‰;δ~(15)N值平均为(4.1±0.7)‰.大型颗粒有机物与小型颗粒有机物之间的δ~(13)C和δ~(15)N值存在极显著正相关关系(P0.01).颗粒有机物和底泥沉积物中δ~(13)C和δ~(15)N值的水平分布具有由上游到下游逐渐增大的规律,颗粒有机物与沉积物之间的δ~(13)C和δ~(15)N值存在显著正相关关系(P0.05).垂直分布中,颗粒有机物的δ~(15)N值是表层大于底层,TN和大型颗粒有机物的δ~(15)N值呈显著正相关(P0.05),POC与颗粒有机物的δ~(15)N值呈极显著正相关关系(P0.01).白石水库水中和沉积物中的有机质主要来源于浮游生物和土壤有机质,颗粒有机物的δ~(13)C值与POC和TP呈显著负相关(P0.05).     

丰水期乌江上游干流水库-河流体系硫同位素组成

2007年7月对乌江上游河流、乌江干流上的3座不同库龄的梯级水库（洪家渡水库、东风水库、乌江渡水库）表层及垂直剖面水体的可溶性硫酸盐的硫同位素组成进行了研究。在垂直剖面上，洪家渡水库硫同位素值（δ34S）介于+03‰~+31‰，下泄水为-07‰；东风水库δ34S值介于-75‰~-55‰，下泄水为-68‰；乌江渡水库δ34S值介于-43‰~-06‰，下泄水为-29‰。上述结论表明，硫同位素组成变化反映了水库硫的不同来源及生物地球化学过程。不同水库表层和垂直剖面水体的硫同位素平均值有差别，水库表层的硫同位素比值主要受输入水体的控制，垂直剖面由表层向下硫同位素比值偏负，主要是由于生物作用以及有机硫的氧化造成的。     

AN ALGORITHM FOR ESTIMATING SURFACE SUSPENDED SEDIMENT CONCENTRATIONS WITH LANDSAT MSS DIGITAL DATA1

ABSTRACT: Algorithms for Landsat MSS digital data are needed to reduce the necessity of calibrating each Landsat scene if these data are to be useful in monitoring programs for surface suspended sediments. In this study digital data were extracted from 16 Landsat Multispectral Scanner (MSS) scenes collected between March 1987 and August 1988 over Enid Reservoir in North Central Mississippi. These data were converted to radiance and reflectance data for comparison with field measurements of surface suspended sediment concentrations. Concentrations ranged from 2 to 168 mg/1 during the study with only four greater than 100 mg/l. Linear and polynomial regression analyses were used to relate the surface suspended sediment concentrations with radiance and reflectance. Reflectance in MSS band 2 (0.6 to 0.7 μm) and MSS band 3 (0.7 to 0.8 μm) were best related to the surface suspended sediment concentrations with coefficients of determination accounting for 71 percent and 68 percent of the variation in the data, respectively. Regressions with radiance data accounted for 36 percent (band 2) or less of the variation. Logarithmic transformations of either reflectance or sediment concentrations increase the coefficients of determination for MSS band 2 reflectance data to 81 percent. Regressions between the ratio of MSS band 1 to MSS band 2 reflectances and concentrations also accounted for 80 percent of the variation. An equation Log_e SS (mg/l) = 9.21R½+ 2.71R½2 + 8.45, where S is surface suspended sediment concentrations and R¹/₂ is the ratio of MSS band 1 to MSS band 2 reflectances, provided the best fit to the data with a coefficient of determination of 0.82. This equation is essentially the same as an algorithm proposed by Topliss et at. (1990), for estimating surface suspended sediment concentrations in Canadian coastal waters. These equations for Enid Reservoir and Canadian waters suggest that it may be possible to develop an algorithm for widespread use for estimating surface suspended sediments.