One-Dimensional Modeling of Sedimentation Impacts for the Mississippi River at the West Bay Diversion

The Coastal Wetlands Planning, Protection and Restoration Act (CWPPRA) funded construction of the West Bay Sediment Diversion Project (WBSD) on the west bank of the Mississippi River for the purpose of coastal restoration. A multi-tiered sediment study for the WBSD was conducted to determine impacts to the adjacent navigation channel and to the Pilottown Anchorage Area (PAA). One tier of the study is the implementation of HEC-6T, a one-dimensional (1-D) sediment model, to evaluate the regional impacts of the WBSD. The HEC-6T model results shows the long-term channel changes associated with the WBSD to be increasing shoaling in the adjacent areas on the order of 10% - 20%, as compared to the no WBSD condition. However, it is extremely difficult to isolate the impacts associated with a single diversion due to multiple diversions in the region. From a holistic vantage point, the 1-D model shows the necessity to examine, on a regional scale, the lower Mississippi River as a single congruent system on a regional scale.

Microbial diversity in cold seep sediments from the northern South China Sea

South China Sea （SCS） is the largest Western Pacific marginal sea. However, microbial studies have never been performed in the cold seep sediments in the SCS. In 2004, ＂SONNE＂ 177 cruise found two cold seep areas with different water depth in the northern SCS. Haiyang 4 area, where the water depth is around 3000 m, has already been confirmed for active seeping on the seafloor, such as microbial mats, authigenic carbonate crusts and bivalves. We investigated microbial abundance and diver- sity in a 5.55-m sediment core collected from this cold seep area. An integrated approach was employed including geochemistry and 16S rRNA gene phylogenetic analyses. Here, we show that microbial abun- dance and diversity along with geochemistry profiles of the sediment core revealed a coupled reaction between sulphate reduction and methane oxidation. Acridine orange direct count results showed that microbial abundance ranges from 105 to 106 cells/g sediment （wet weight）. The depth-related variation of the abundance showed the same trend as the methane concentration profile. Phylogenetic analysis indicated the presence of sulphate-reducing bacteria and anaerobic methane-oxidizing archaea. The diver- sity was much higher at the surface, but decreased sharply with depth in response to changes in the geochemical conditions of the sediments, such as methane, sulphate concentration and total organic carbon. Marine Benthic Group B, Chloroflexi and JS1 were predominant phylotypes of the archaeal and bacterial libraries, respectively.

The bacterial diversity in surface sediment from the South China Sea

16S rDNA sequencing results from this study and literatures demonstrate that sediment bacteria in the South China Sea （SCS） were very diverse,which contained 22 of the 24 phyla of bacteria investigated from marine sediment,however,it was very imbalance among stations.So bacterial diversity from 15 samples which covered a wide range of sediment types from 20 to 3 888 m in depth was studied in DGGE （denature gradient gel electrophoresis） in this paper.The DGGE results indicate that both sediment bacterial diversity and diversity difference among stations were significant.Thirty representative and differential fingerprints among samples were recovered and sequenced,phylogenetic analysis indicates that they may belong to Proteobacteria （α-,β-,γ-,δ-,ε-）,Planctomycetes,Firmicutes,Chloroflexi,Acidobacteria,Actinobacteria,Nitrospirae,Gemmatimonadetes,candidate division WS3 and so on,of which,Gemmatimonadetes and candidate division WS3 bacteria were first detected in SCS sediment.This study also shows that bacterial diversity analysis based on DGGE was more potential than traditional 16S rDNA clone library in multiple sample analysis.

Bacterial diversity in the sediments collected from the Shikoku Basin

Diversity of bacteria was studied in deep-sea sediments from the Shikoku Basin in the Northwest Pacific Ocean by PCR, RFLP and sequence analysis of 16S rDNA and comparing with Genbank database. Based on the RFLP profile generated, 77 clones from the 16S rDNA library were divided into 27 types. Phylogenetic analysis showed that the 27 independent clones fell into four groups: Proteobac-teria (62.96%), Chloroflexi (14.81%), Planctomycetes (14.81%) and Acidobacteria (7.41%). Among all sequenced clones, 6 were related to the sulfur or sulfate metabolism bacteria and the results also demonstrated that some bacteria in deep-sea sediments had relation to matter-energy circulation.

Impact of redox-stratification on the diversity and distribution of bacterial communities in sandy reef sediments in a microcosm

Relationships between microbial communities and geochemical environments are important in marine microbial ecology and biogeochemistry. Although biogeochemical redox stratification has been well documented in marine sediments, its impact on microbial communities remains largely unknown. In this study, we applied denaturing gradient gel electrophoresis （DGGE） and clone library construction to investigate the diversity and stratification of bacterial communities in redox-stratified sandy reef sediments in a microcosm. A total of 88 Operational Taxonomic Units （OTU） were identified from 16S rRNA clone libraries constructed from sandy reef sediments in a laboratory microcosm. They were members of nine phyla and three candidate divisions, including Proteobacteria （Alphas, Beta-, Gamma-, Delta-, and Epsilonproteobacteria）, Aetinobacteria, Acidobacteria, Bacteroidetes, Chloroflexi, Cyanobacteria, Firmicutes, Verrucomicrobia, Spirochaetes, and the candidate divisions WS3, SO31 and AO19. The vast majority of these phylotypes are related to clone sequences from other marine sediments, but OTUs of Epsilonproteobacteria and WS3 are reported for the first time from permeable marine sediments. Several other OTUs are potential new bacterial phylotypes because of their low similarity with reference sequences. Results from the 16S rRNA, gene clone sequence analyses suggested that bacterial communities exhibit clear stratification across large redox gradients in these sediments, with the highest diversity found in the anoxic layer （15-25 mm） and the least diversity in the suboxic layer （3-5 mm）. Analysis of the nosZ, and amoA gene libraries also indicated the stratification of denitrifiers and nitrifiers, with their highest diversity being in the anoxic and oxic sediment layers, respectively. These results indicated that redox-stratification can affect the distribution of bacterial communities in sandy reef sediments.

Bacterial diversity in Arctic marine sediment determined by culture-dependent and-independent approaches

Bacterial diversity in surface sediment from the Arctic Ocean was investigated by culture-dependent and-independent approaches. Conventional culture-dependent techniques revealed 11 strains based on their distinct morphological characteristics on marine Zobell 2216E agar plates. Phylogenetic analysis showed that these isolates belonged to three major lineages of the Bacteria,γ-proteobacteria, Bacteroidetes and Actinobacteria, and that they included 10 genera. Most isolates were psychrotrophic, and NaCl was not necessary for their growth. Furthermore, they exhibited activity of at least one extracellular hydrolytic enzyme at 4＆#176;C and had various abilities to assimilate carbon sources. A total of 67 phylotypes were detected among 142 clones based on the 16S rRNA library of the total community DNA and grouped into nine major lineages of bacteria. Phylotypes afifliated withγ-,δ-andε-proteobacteria accounted for 36.7%, 21.8%and 16.9%of the total clones, respectively. The rest of the clones belonged to Bacteroidetes,α-proteobacteria, Actinobacteria, Fusobacteria, Nitrospirae and an unclassiifed group.

Distribution of ammonia-oxidizing Betaproteobacteria community in surface sediment off the Changjiang River Estuary in summer

The spatial distribution of ammonia-oxidizing Betaproteobacteria （βAOB） was investigated by FISH （fluorescence in situ hybridization） and DGGE （denaturing gradient get electrophoresis） techniques in the sediment off the Changjiang River Estuary. Sediment samples were collected from eight stations in June before the formation of hypoxia zone in 2006. The abundance of βAOB ranged from 1.87× 10^5 to 3.53×10^5 cells/g of sediment. βAOB abundance did not present a negative correlation with salinity, whereas salinity was implicated as the primary factor affecting nitrification rates. The DGGE profiles of PCR-amplified amoA gene fragments revealed that the βAOB community structure of sample S2 separated from other samples at the level of 40% similarity. The variations in composition ofβAOB were significantly correlated with the salinity, temperature, absorption ability of sediments and TOC. The statistical analysis indicates that theβAOB abundance was a main factor to influence nitrification rates with an influence ratio of 87.7% at the level of 40% biodiversity similarity. Considering the good correlation between βAOB abundance and nitrification estimates, the abundance and diversity of βAOB community could be expected as an indirect index of nitrification activity at the study sea area in summer.

Characterization of depth-related microbial communities in lake sediment by denaturing gradient gel electrophoresis of amplified 16S rRNA fragments

The characterization of microbial communities of different depth sediment samples was examined by a culture-independent method and compared with physicochemical parameters, those are organic matter （OM）, total nitrogen （TN）, total phosphorus （TP）, pH and redox potential （Eh）. Total genomic DNA was extracted from samples derived from different depths. After they were amplified with the GC-341 f/907r primer sets of partial bacterial 16S rRNA genes, the products were separated by denaturing gradient gel electrophoresis （DGGE）. The profile of DGGE fingerprints of different depth sediment samples revealed that the community structure remained relatively stable along the entire 45 cm sediment core, however, principal-component analysis of DGGE patterns revealed that at greater sediment depths, successional shifts in community structure were evident. The principle coordinates analysis suggested that the bacterial communities along the sediment core could be separated into two groups, which were located 0-20 cm and 21-45 cm, respectively. The sequencing dominant bands demonstrated that the major phylogenetic groups identified by DGGE belonged to Bacillus, Bacterium, Brevibacillus, Exiguobacterium, γ-Proteobacterium, Acinetobacter sp. and some uncultured or unidentified bacteria. The results indicated the existence of highly diverse bacterial community in the lake sediment core.

Analysis of effect of nicotine on microbial community structure in sediment using PCR-DGGE fingerprinting

Solid or liquid waste containing a high concentration of nicotine can pollute sediment in rivers and lakes, and may destroy the ecological balance if it is directly discharged into the environment without any treatment. In this study, the polymerase chain reaction （PCR） and denaturing gradient gel electrophoresis （DGGE） method was used to analyze the variation of the microbial community structure in the control and nicotinecontaminated sediment samples with nicotine concentration and time of exposure. The results demonstrated that the growth of some bacterial species in the nicotine-contaminated sediment samples was inhibited during the exposure. Some bacteria decreased in species diversity and in quantity with the increase of nicotine concentration or time of exposure, while other bacteria were enriched under the effect of nicotine, and their DGGE bands changed from undertones to deep colors. The microbial community structure, however, showed a wide variation in the nicotine- contaminated sediment samples, especially in the sediment samples treated with high-concentration nicotine. The Jaccard index was only 35.1% between the initial sediment sample and the sediment sample with a nicotine concentration of 0.030 μg/g after 28 d of exposure. Diversity indices showed that the contaminated groups had a similar trend over time. The diversity indices of contaminated groups all decreased in the first 7 d after exposure, then increased until day 42. It has been found that nicotine decreased the diversity of the microbial community in the sediment.

Aerobic biodegradation of di-n-butyl phthalate by Xiangjiang River sediment and microflora analysis

Di-n-butyl phthalate (DBP),one of phthalate acid esters (PAEs),was investigated to determine its biodegradation rate using Xiangjiang River sediment and find potential DBP degraders in the enrichment culture of the sediment. The sediment sample was incubated with an initial concentration of DBP of 100 mg/L for 5 d. The biodegradation rate of DBP was detected using HPLC and the degraded products were analyzed by GC/MS. Subsequently,the microbial diversity of the enrichment culture was analyzed by polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP). The results reveal that almost 100% of DBP is degraded after merely 3 d,generating two main degraded products:mono-butyl phthalate (MBP) and 9-octadecenoic acid. After a six-month enrichment period under the pressure of DBP,the dominant family in the final enrichment culture is clustered with the Comamonas sp.,the remaining are affiliated with Sphingomonas sp.,Hydrogenophaga sp.,Rhizobium sp.,and Acidovorax sp. The results show the potential of these bacteria to be used in the bioremediation of DBP in the environment.

Bacterial and archaeal community structure of pan-Arctic Ocean sediments revealed by pyrosequencing

This study was to investigate bacterial and archaeal community structure of pan-Arctic Ocean sediments by pyrosequencing. In total, investigation of three marine sediments revealed 15 002 bacterial and 4 362 archaeal operational taxonomic units （OTUs） at the 97% similarity level. Analysis of community structure indicated that these three samples had high bacterial and archaeal diversity. The most relatively abundant bacterial group in Samples CC 1 and R05 was Proteobacteria, while Firmicutes was dominant in Sample BL03. Thaumarchaeota was the most relatively abundant archaeal phylum in Samples CC1 and R05, and the relative abundance of Thaumarchaeota was almost as high as that of Euryarchaeota in Sample BL03. These two phyla accounted for nearly 100% of the archaeal OTUs. 6-Proteobacteria and y-Proteobacteria were the two most relatively abundant classes at Proteobacterial class level, and their relative abundance was more than 60% in Samples CC1 and R05. There were also differences in the top 10 relatively abundant bacterial and archaeal OTUs among the three samples at the 97% similarity, and only 12 core bacterial OTUs were detected. Overall, this study indicated that there were distinct microbial communities and many unique OTUs in these three samples.

A STUDY ON THE WATER RESOURCES AND SEDIMENT PROBLEMS IN THE IRRIGATED AREA OF NORTHWEST SHANDONG PROVINCE

There are very serious water and sediment problems in the irrigated areas of northwest Shandong Province. In upper reaches of the irrigated area, the Yellow River water are widely used for farmland watering while leaving the ground water unusedion. But in the lower reaches, there is not enough surface water to be channeled for irrigation, so the ground water has always been over extracted, in some parts of the lower reaches, the descending water table caused the formation of funnel. Siltation in canals are very difficult to be cleared up, the drop of agriculture yield in the sandy land close to the channel head and along the main channels impair the living conditions of the local people. The conflicts between the excessive dependence on the Yellow River and the decreasing tendancy of water amount provided by the Yellow Ricer forces the local government to find new ways to solve the water resource problems. The answer could be: Using new technique for the irrigated system, pay more attention to the ground water development, and the construction and maintenance of wells.

Assessment of Sediment and Benthic Macrofauna Distribution at Dar es Salaam Harbour Channel

Sediment and macrobenthic fauna distribution at Dar es Salaam harbour channel were investigated to attest the influence of sediment grain size distribution and total organic carbon contents on benthic macrofauna dominance and diversity. Sampling campaign was conducted from January to April, 2019 in 25 sampling stations along the channel. Sediment grain sizes ranged between 0.7405 and 0.00273 mm with an average of 0.0804 mm classified as medium silt. Sediment distribution showed an onshore-offshore pattern consisting of fine dark clay-silt sediments in the southern part of the harbour close to Mwalimu Nyerere Bridge, medium (sandy) at the harbour and coarse sandy offshore. Five classes of macrofauna were identified with sedentary Polychaetes (Diopatra cuprea) found in tubes and free forms being dominant in most of the sediment types, however more abundant in clay-silt. High species diversity index values were encountered in sediments with medium total organic carbon (TOC) and sediment grain sizes (sand-silt). Apparently, low species similarity indices were observed in all sediment type indicating significant dissimilarities in species composition among sediment grain sizes. Thus, the distribution of benthic macrofauna species along Dar es Salaam harbour channel is strongly influenced by the sediment grain sizes and organic carbon contents in sediments.

Umbrella Labyrinth Sedimentation Device Study

Umbrella-type mud-water diversion labyrinth sedimentation device,which is characterized by the combination of two swash plate and wing plate into an umbrella type with a set angle,the angle range of the two swash plate is 15º--100º,the vertical height of the swash plate is 60-70 mm,the parallel axis of the wing plate is the vertical direction,the height is 10-20 mm.the whole adopts the modular combination mode,and can be freely combined and disassembled according to different pond design,swash plate The interval(sedimentation distance)can be freely adjusted,mud take the mud road and water take the water road,to avoid the mutual interference of the water and mud road,to achieve the stability of the water quality.The turbidity of the sedimentation pond is low,stable in 0.3-2.0 NTU.

抽水蓄能电站防沙措施研究

以典型抽水蓄能电站为研究对象,开展了水库防沙措施研究。针对复杂工程条件,在分析各种防沙布置措施的基础上,考虑以沉代拦、导沉结合,提出导沙堤和尾水明渠相结合的防沙布置型式。经过数值模拟和物理模型验证,该型式减少过机泥沙效果明显,水力学参数合理。研究成果可为类似工程规划、设计和运行提供参考。

鱼和砷对湖泊水体和沉积物细菌群落的影响

湖泊是水体生物多样性的一个重要存储库,湖泊砷污染问题在全球范围内被广泛关注,然而鱼扰动和砷污染的联合作用对水体和沉积物微生物影响研究却很少报道.鉴于此,本研究通过室内模拟湖泊生态系统,并采用高通量测序技术以探究鱼类活动和砷污染下湖泊水体和沉积物细菌群落的响应机制.研究结果表明,沉积物细菌多样性显著高于水体和鱼组织中细菌多样性.鱼和砷均能引起水体和沉积物细菌群落的改变,鱼和砷的共同作用可使沉积物细菌多样性显著降低,同时可导致水体中黄杆菌属(Flavobacterium)和红杆菌属(Rhodobacter)的含量显著降低.这些结果有利于深入了解湖泊水体和沉积物细菌群落,为开展污染物和生物扰动联合作用下的生态风险研究提供科学依据.

六垛南闸下游引河泥沙淤积特性数值分析

为了明确六垛南闸下游引河的淤积特性,基于Mike软件数值计算求解了该闸下游引河的水沙运动,对闸下引河冲淤进行了预测分析,并通过闸下实测水位和预测水位进行对比验证了计算模型的正确性。结果表明:各泄流量时下游引河的水流均为顺岸流动,流速分布规律相同;相同流量时沿程流速整体呈增大趋势。闸下引河的冲淤特性呈现出潮位越低,冲淤量越大的特点。建议六垛南闸开闸冲淤应尽量选择入海口潮位<0.3m时进行,同时可按照10d一个周期进行开闸冲淤。研究成果可为江苏省同类沿海挡潮闸防淤减淤提供参考。

分汊河道对极端洪水的响应研究——以北江伦洲河段为例

为探究分汊河段河流形态和水动力学特性对极端洪水的响应,以北江下游清远伦洲河段为例,通过实地调研、河床演变分析和数值模拟的方法,系统研究了该河段在2022年6月超百年一遇洪水期间水流运动特性,以及洪水后河床冲淤变化、泥沙粒径分布和水位变化情况。结果表明:“22·6”洪水期间,水流主流在惯性作用下向左侧偏转并对伦洲岛岛头区域产生直接冲击,从而造成该区域基础设施损毁严重;水流冲出峡谷后由于流速降低、挟沙能力下降,导致岛头区域和河道右汊淤积严重,河道左汊则呈冲刷态势;由于岛头区域和河道左、右汊流速差异,导致泥沙粒径分布存在差异,其中岛头区域泥沙粒径明显大于左、右汊河床泥沙粒径;“22·6”洪水后由于河床抬升,水位较洪水前明显壅高,左汊分流比增大,在来流为5000 m^(3)/s条件下,岛头上游水位壅高接近1 m,左汊分流比较洪水前增加约16%。

哈尔滨地区精养/半精养池塘底泥细菌群落分析及其与环境因子相关性

为了探究哈尔滨地区精养(JY)和半精养(CF)2种养殖模式下,主养鲤(Cyprinus carpio)池塘底泥细菌群落结构特征,采用16S rDNA高通量测序方法分析了2种池塘底泥细菌群落及其PICRUSt功能预测,并利用主成分分析法解析了环境因子与细菌群落结构的相关性。污染指数评价结果表明精养池塘水质优于半精养池塘,水体总氮(TN)、总磷(TP)浓度均低于半精养池塘,但差异不显著(P>0.05),而总有机碳(TOC)浓度显著低于半精养池塘(P<0.05)。半精养池塘水体及底泥酸碱度(pH)均显著低于精养池塘(P<0.05)。精养池塘底泥细菌群落α-多样性指数均高于半精养池塘,但差异不显著(P>0.05),其中的香农(Shannon)和辛普森(Simpson)指数与底泥中氨氮(NH^(+)_(4)-N)浓度呈正相关关系。2个池塘底泥中优势菌门分布较为一致,共有优势菌门为变形菌门(Proteobacteria)、绿弯菌门(Chloroflexi)、酸杆菌门(Acidobacteria)和拟杆菌门(Bacteroidetes);但优势菌属存在一定差异,精养池塘的则为史密斯氏菌属(Smithella)和狭义梭菌属(Clostridium_sensu_stricto),而半精养池塘的优势菌属为铁矿单胞菌属(Arenimonas)、藤黄色单胞菌属(Luteimonas)。2个养殖池塘底泥菌群的主要功能基本一致,但两者代谢过程存在显著性差异(P<0.05)。主成分分析结果表明水体NH^(+)_(4)-N、pH、TOC及底泥pH是影响2种池塘底泥菌群结构的主要环境因子。研究结果为渔业生产方式引起环境因子变化,从而对养殖池塘底泥细菌群落结构的影响及深度认识池塘生态系统微生物作用和功能提供理论、数据支持。