Source identification, geochemical normalization and influence factors of heavy metals in Yangtze River Estuary sediment.

PubMed

Sun, Xueshi; Fan, Dejiang; Liu, Ming; Tian, Yuan; Pang, Yue; Liao, Huijie

2018-06-18

Sediment samples, including 40 surface samples and 12 sediment cores, were collected from 52 stations of the Yangtze River Estuary (YRE) in 2015 and 2016. The 95% linear prediction intervals (LPI) and principal components analysis (PCA), were conducted to evaluate the metal sources and grain-size effect (GSE). The in situ physico-chemical properties of pH, Eh, DO, salinity, temperature and turbidity were combined to elucidate the relationships between environmental factors and the fate of heavy metals in the river-estuary-shelf system. This study indicates a decreasing trend of metals in sediments from the estuary towards the adjacent shelf and the river channel and that Zn, Cu and Cr are mainly derived from natural processes throughout the catchment, whereas Pb appears to have anthropogenic inputs via atmospheric deposition. Furthermore, considering the best fit regression lines between the concentrations of Al and heavy metals as well as the deficiencies of the conventional C elements /C Al method, we introduce an approach (Al-SN: Al-scope normalization) that can eliminate the GSE on heavy metals and be applied to other estuaries. After Al-scope normalization, the relatively constant levels of Zn, Cu and Cr that remain in sediments from the river channel to the estuary and shelf confirmed that the variation of grain size in sediments almost entirely explained the distribution patterns of sediment toxicity in the YRE, while the enrichment of Pb in estuarine sediments could be attributed to its chemical species and physico-chemical properties. The results further suggest that the relationship between grain size and spatial behavior of sediment pollutants should be given priority over the contamination assessment and provenance discrimination in estuarine or similar environments with complex sediment compositions. Copyright © 2018 Elsevier Ltd. All rights reserved.

[Speciation and Risk Characteristics of Heavy Metals in the Sediments of the Yangtze Estuary].

PubMed

Yin, Su; Feng, Cheng-hong; Li, Yang-yang; Yin, Li-feng; Shen, Zhen-yao

2016-03-15

Based on the investigation on the distribution of total contents and speciation of 8 heavy metals (As, Cd, Cr, Cu, Hg, Ni, Pb, Zn) in the surface sediments at 14 typical sites of the Yangtze Estuary during three hydrological seasons ( wet, normal, and dry seasons) , this study applied equilibrium partitioning approach to build the sediment quality guidelines (SQGs) of the Yangtze Estuary, and assessed ecological risks of the heavy metals. The relationship between ecological risk and speciation of heavy metals was also revealed. The results showed that, except for Cd, the residual fraction was the main speciation of heavy metals, especially for As, Cr and Hg, their residual fraction proportions were all over 90%. The sediment quality guidelines of the Yangtze Estuary for As, Cd, Cr, Cu, Hg, Ni, Pb, Zn were 43.29, 0.672, 79.65, 19.08, 0.569, 339.09, 30.87, 411.36 µg · g⁻¹, respectively. Cu had the highest ecological risk to aquatic organisms. The upstream of Yangtze Estuary was mainly affected by Yangtze River runoff, where the risks were relatively high in wet season and relatively low in normal and dry seasons. However, the downstream of the estuary was mainly affected by municipal sewage of cities like Shanghai, where the risks were relatively high, especially in normal and dry seasons. There were three different relationships between the ecological risks and speciation of the eight heavy metals.

Perfluoroalkyl and polyfluoroalkyl substances in the lower atmosphere and surface waters of the Chinese Bohai Sea, Yellow Sea, and Yangtze River estuary.

PubMed

Zhao, Zhen; Tang, Jianhui; Mi, Lijie; Tian, Chongguo; Zhong, Guangcai; Zhang, Gan; Wang, Shaorui; Li, Qilu; Ebinghaus, Ralf; Xie, Zhiyong; Sun, Hongwen

2017-12-01

Polyfluoroalkyl and perfluoroalkyl substances (PFASs), in the forms of neutral polyfluoroalkyl substances in the gas phase of air and ionic perfluoroalkyl substances in the dissolved phase of surface water, were investigated during a sampling campaign in the Bohai Sea, Yellow Sea, and Yangtze River estuary in May 2012. In the gas phase, the concentrations of neutral ∑PFASs were within the range of 76-551pg/m 3 . Higher concentrations were observed in the South Yellow Sea. 8:2 fluorotelomer alcohol (FTOH) was the predominant compound as it accounted for 92%-95% of neutral ∑PFASs in all air samples. Air mass backward trajectory analysis indicated that neutral ∑PFASs came mainly from the coast of the Yellow Sea, including the Shandong, Jiangsu, and Zhejiang provinces of China, and the coastal region of South Korea. The fluxes of gas phase dry deposition were simulated for neutral PFASs, and neutral ∑PFASs fluxes varied from 0.37 to 2.3pg/m 2 /s. In the dissolved phase of the surface water, concentrations of ionic ∑PFASs ranged from 1.6 to 118ng/L, with the Bohai Sea exhibiting higher concentrations than both the Yellow Sea and the Yangtze River estuary. Perfluorooctanoic acid (PFOA) was the predominant compound accounting for 51%-90% of the ionic ∑PFAS concentrations. Releases from industrial and domestic activities as well as the semiclosed geographical conditions increased the level of ionic ∑PFASs in the Bohai Sea. The spatial distributions of perfluoroalkyl carboxylic acids (PFCAs) and perfluoroalkane sulfonic acids (PFSAs) were different significantly. The Laizhou Bay was the major source region of PFCAs and the Yangtze River estuary was the major source of PFSAs. Copyright © 2017 Elsevier B.V. All rights reserved.

Research Note:Effects of human activities on the Yangtze River suspended sediment flux into the estuary in the last century

NASA Astrophysics Data System (ADS)

Yang, S. L.; Shi, Z.; Zhao, H. Y.; Li, P.; Dai, S. B.; Gao, A.

The surface erosion area in the Yangtze River basin increased from 364×103 km2 in the 1950s to 707×103 km2 in 2001 due to a great increase in population. Based on the regression relationship between surface erosion area and population, the surface erosion area was predicted to be about 280×103 km2 at the beginning of the 20th century. The sediment yield, which increased by about 30% during the first six decades of the 20th century, was closely related to the surface erosion area in this river basin. The Yangtze annual suspended sediment flux into the estuary was about 395×106 t a-1 at the beginning of the century, and this gradually increased to an average of 509×106 t a-1 in the 1960s. The increase in the suspended sediment flux into the estuary was accelerated in the 1950s and the 1960s due to the rapid increase in population and land use immediately after the Second World War and the Liberation War. After the riverine suspended sediment flux reached its maximum in the 1960s, it decreased to <206×106 t a-1 in 2003. Construction of dams was found to be the principal cause for this decreasing trend because, during the same period, (a) the riverine water discharge did not show a decreasing trend, (b) water diversion was not influential and (c) sedimentation in lakes and canals of the middle and lower reaches did not increase. The total storage capacity of reservoirs has increased dramatically over the past half century. The amount of sediment trapped in reservoirs has increased to more than half a billion t a-1. As a result, the suspended sediment flux into the estuary dramatically decreased, even though the sediment yield from many areas of the basin increased in recent decades. Human activities gradually increased the suspended sediment flux into the estuary before the 1960s and then rapidly decreased it. The last century was a period when the Yangtze suspended sediment flux into the estuary was dramatically affected by human activities.

[Distributions and air-sea fluxes of dissolved nitrous oxide in the Yangtze River estuary and its adjacent marine area in spring and summer].

PubMed

Wang, Lan; Zhang, Gui-ling; Sun, Ming-shuang; Ren, Jing-ling

2014-12-01

Distributions and air-sea fluxes of nitrous oxide (N2O) in the seawaters of the Yangtze River estuary and its adjacent marine area were investigated during two cruises in March and July 2012. Dissolved N2O concentrations in surface waters ranged from 9.34 to 49.08 nmol x L(-1) with an average of (13.27 ± 6.40) nmol x L(-1) in spring and ranged from 7.27 to 27.81 nmol x L(-1) with an average of (10.62 ± 5.03) nmol x L(-1) in summer. There was no obvious difference between surface and bottom N2O concentrations. N2O concentrations in both surface and bottom waters decreased along the freshwater plume from the river mouth to the open sea. High values of dissolved N2O were found in turbidity maximum zone, which suggests that maximal turbidity enhances nitrification. Temperature had dual effects on dissolved N2O concentrations. N2O saturations in surface waters ranged from 86.9% to 351.3% with an average of (111.5 ± 41.4)% in spring and ranged from 111.7% to 396.0% with an average of (155.9 ± 68.4)% in summer. N2O were over-saturated at most stations. The sea-to-air fluxes of N2O were estimated to be (3.2 ± 10.9), (5.5 ± 19.3) and (12.2 ±52.3) μmol x (m2 x d)(-1) in spring and (7.3 ± 12.4), (12.7 ± 20.4) and (20.4 ± 35.9) μmol x (m2 x d)(-1) in summer using the LM86, W92 and RC01 relationships, respectively. The annual emissions of N2O from the Yangtze River estuary and its adjacent marine area were estimated to be 0.6 x 10(-2) Tg x a(-1) (LM86), 1.1 x 10(-2) Tg x a(-1) (W92) and 2.0 x 10(-2) Tg x a(-1) (RC01). Although the area of the Yangtze River estuary and its adjacent marine area only accounts for 0.02% of the total area of the world's oceans, their emission of N2O accounts for 0.06% of global oceanic N2O emission, indicating that the Yangtze River estuary and its adjacent marine area is an active area to produce and emit N2O.

Spatio-temporal distribution and environmental risk of sedimentary heavy metals in the Yangtze River Estuary and its adjacent areas.

PubMed

Chen, Bin; Liu, Jian; Qiu, Jiandong; Zhang, Xilin; Wang, Shuang; Liu, Jinqing

2017-03-15

Twenty-five surface sediments and one sediment core sample were collected from the study area. Grain size, major elements, and heavy metals were determined. The content of fine-grained sediments (silt and clay), as well as the concentrations of major elements and heavy metals, showed seaward decreasing trends, with high content in the coastal areas of the East China Sea (ECS) and south west of Jeju Island. Low enrichment factor (EF) and geoaccumulation index (Igeo) values were found, indicating that the ecological risk of heavy metals was low. The EF values obtained from the high-resolution sedimentary records of heavy metals in the Yangtze River Estuary could be divided into Stage 1 (1950s to the late 1970s) and Stage 2 (late 1970s to the current sampling day), which coincided with economic development of the Yangtze River Basin, implementation of environmental protection, and impoundment of the Three Gorges Dam. Copyright © 2016. Published by Elsevier Ltd.

Morphodynamic Evolution of Yangtze (Changjiang) Estuary in Decadal-timescale: Alteration from Natural Processes to Human Interferences

NASA Astrophysics Data System (ADS)

Luan, H.; Ding, P.; Ge, J.; Zong, H.; Zheng Bing, W.

2016-02-01

Morphodynamic development of river deltas has attracted intensive attention in the past several decades due to ecological and economic significance. Present study quantified the morphological evolution processes of the Yangtze Estuary in decadal-timescale (1958-2010) aiming at understanding the effects of natural processes (river inputs) on the estuary and its morphological responses to human interferences. Inner Estuary (IE) and Mouth Bar Area (MBA) underwent substantially different changes in the study period. The net accretion rate of IE was 36.2 mm/yr in 1958-1978 and -70.9 mm/yr in 1986-1997, indicating that the IE altered from deposition to erosion along with the decline of river sediment input. By contrast, the MBA showed sustained accretion throughout the study period. The results suggested that the IE is more sensitive to the river sediment reduction than the MBA. The river flood may induce erosion in IE which can explain the erosion peak in 1986-1997 since there are continuous flood years in 1990s. The majority of erosion within IE in 1986-1997 occurred in South Branch. The depocenter within MBA transferred between the North Channel and the South Passage. Specifically, the depocenter was in the South Passage during 1958-1978, in the North Channel during 1978-1986, and back to the South Passage during 1986-1997. This is thought to be caused by the change in sediment diversion between the South and North Channel, except 1986-1997. Highest accretion rate (48.9mm/yr) in 1997-2010 is found within the North Passage if excluding the effects of navigation channel dredging. Previous research has quantified the morphological changes along the North Passage and attributed high deposition to the construction of dikes and perpendicular groins. The fluvial-marine transition in terms of prevailing forcing and sediment property is the natural characteristics of river deltas and play an essential role on morphological development of Yangtze Estuary. Present evidence shows

Solution by dilution?--A review on the pollution status of the Yangtze River.

PubMed

Floehr, Tilman; Xiao, Hongxia; Scholz-Starke, Björn; Wu, Lingling; Hou, Junli; Yin, Daqiang; Zhang, Xiaowei; Ji, Rong; Yuan, Xingzhong; Ottermanns, Richard; Roß-Nickoll, Martina; Schäffer, Andreas; Hollert, Henner

2013-10-01

The Yangtze River has been a source of life and prosperity for the Chinese people for centuries and is a habitat for a remarkable variety of aquatic species. But the river suffers from huge amounts of urban sewage, agricultural effluents, and industrial wastewater as well as ship navigation wastes along its course. With respect to the vast amounts of water and sediments discharged by the Yangtze River, it is reasonable to ask whether the pollution problem may be solved by simple dilution. This article reviews the past two decades of published research on organic pollutants in the Yangtze River and several adjacent water bodies connected to the main stream, according to a holistic approach. Organic pollutant levels and potential effects of water and sediments on wildlife and humans, measured in vitro, in vivo, and in situ, were critically reviewed. The contamination with organic pollutants, including polycyclic aromatic hydrocarbons, polychlorinated biphenyls (PCBs), organochlorine pesticides (OCPs), polychlorinated dibenzo-p-dioxins/polychlorinated dibenzofurans, polybrominated diphenyl ethers (PBDEs), perfluorinated compounds (PFCs), and others, of water and sediment along the river was described. Especially Wuhan section and the Yangtze Estuary exhibited stronger pollution than other sections. Bioassays, displaying predominantly the endpoints mutagenicity and endocrine disruption, applied at sediments, drinking water, and surface water indicated a potential health risk in several areas. Aquatic organisms exhibited detectable concentrations of toxic compounds like PCBs, OCPs, PBDEs, and PFCs. Genotoxic effects could also be assessed in situ in fish. To summarize, it can be stated that dilution reduces the ecotoxicological risk in the Yangtze River, but does not eliminate it. Keeping in mind an approximately 14 times greater water discharge compared to the major European river Rhine, the absolute pollution mass transfer of the Yangtze River is of severe concern for

Richness and diversity of helminth communities in the Japanese grenadier anchovy, Coilia nasus, during its anadromous migration in the Yangtze River, China.

PubMed

Li, Wen X; Zou, Hong; Wu, Shan G; Song, Rui; Wang, Gui T

2012-06-01

To determine the relationship between the species richness, diversity of helminth communities, and migration distance during upward migration from coast to freshwater, helminth communities in the anadromous fish Coilia nasus were investigated along the coast of the East China Sea, the Yangtze Estuary, and 3 localities on the Yangtze River. Six helminth species were found in 224 C. nasus . Changes in salinity usually reduced the survival time of parasites, and thus the number of helminth species and their abundance. Except for the 2 dominant helminths, the acanthocephalan Acanthosentis cheni and the nematode Contracaecum sp., mean abundance of other 4 species of helminths was rather low (<1.0) during the upward migration in the Yangtze River. Mean abundance of the 2 dominant helminths peaked in the Yangtze Estuary and showed no obvious decrease among the 3 localities on the Yangtze River. Mean species richness, Brillouin's index, and Shannon index were also highest in the estuary (1.93 ± 0.88, 0.28 ± 0.25, and 0.37 ± 0.34, respectively) and did not exhibit marked decline at the 3 localities on the Yangtze River. A significant negative correlation was not seen between the similarity and the geographical distance (R  =  -0.5104, P  =  0.1317). The strong salinity tolerance of intestinal helminths, relatively brief stay in the Yangtze River, and large amount of feeding on small fish and shrimp when commencing spawning migration perhaps were responsible for the results.

[Effects of macro-jellyfish abundance dynamics on fishery resource structure in the Yangtze River estuary and its adjacent waters].

PubMed

Shan, Xiu-Juan; Zhuang, Zhi-Meng; Jin, Xian-Shi; Dai, Fang-Qun

2011-12-01

Based on the bottom trawl survey data in May 2007 and May and June 2008, this paper analyzed the effects of the abundance dynamics of macro-jellyfish on the species composition, distribution, and abundance of fishery resource in the Yangtze River estuary and its adjacent waters. From May 2007 to June 2008, the average catch per haul and the top catch per haul of macro-jellyfish increased, up to 222.2 kg x h(-1) and 1800 kg x h(-1) in June 2008, respectively. The macro-jellyfish were mainly distributed in the areas around 50 m isobath, and not beyond 100 m isobath where was the joint front of the coastal waters of East China Sea, Yangtze River runoff, and Taiwan Warm Current. The main distribution area of macro-jellyfish in June migrated northward, as compared with that in May, and the highest catches of macro-jellyfish in May 2007 and May 2008 were found in the same sampling station (122.5 degrees E, 28.5 degrees N). In the sampling stations with higher abundance of macro-jellyfish, the fishery abundance was low, and the fishery species also changed greatly, mainly composed by small-sized species (Trachurus japonicus, Harpadon nehereus, and Acropoma japonicum) and pelagic species (Psenopsis anomala, Octopus variabilis) and Trichiurus japonicus, and P. anomala accounted for 23.7% of the total catch in June 2008. Larimichthys polyactis also occupied higher proportion of the total catch in sampling stations with higher macro-jellyfish abundance, but the demersal species Lophius litulon was not found, and a few crustaceans were collected. This study showed that macro-jellyfish had definite negative effects on the fishery community structure and abundance in the Yangtze River estuary fishery ecosystem, and further, changed the energy flow patterns of the ecosystem through cascading trophic interactions. Therefore, macro-jellyfish was strongly suggested to be an independent ecological group when the corresponding fishery management measures were considered.

Antibiotics in the surface water of the Yangtze Estuary: occurrence, distribution and risk assessment.

PubMed

Yan, Caixia; Yang, Yi; Zhou, Junliang; Liu, Min; Nie, Minghua; Shi, Hao; Gu, Lijun

2013-04-01

The occurrence and distribution of five groups of antibiotics were investigated in the surface water of Yangtze Estuary over four seasons. Of the 20 antibiotics, only sulfamerazine was not detected at all sampling sites, indicating widespread occurrence of antibiotic residues in the study area. Detection frequencies and concentrations of antibiotics were generally higher in January, indicating that low flow conditions and low temperature might enhance the persistence of antibiotics in water. Antibiotic levels varied with location, with the highest concentrations being observed around river discharge and sewage outfall. Furthermore, a positive correlation between total antibiotic and DOC concentrations revealed the significant role played by DOC. Risk assessment based on single compound exposure showed that sulfapyridine and sulfamethoxazole could cause medium risk to daphnid in the Yangtze Estuary. Copyright © 2012 Elsevier Ltd. All rights reserved.

GF-1 and Landsat observed a 40-year wetland spatiotemporal variation and its coupled environmental factors in Yangtze River estuary

NASA Astrophysics Data System (ADS)

Sun, Nan; Zhu, Weining; Cheng, Qian

2018-07-01

Wetlands are health indicators of aquatic ecosystems and also vulnerable to regional environmental and socio-economic changes. For exploring wetland spatiotemporal variations in estuarine and coastal regions of the Yangtze River, we extracted wetland information from 40-year time-series images of Landsat, GF-1, and other satellites, using the classification method of decision tree. Potential environmental and socio-economic factors which may drive wetland variations were analyzed. Results show that the wetland area in Yangtze River estuary has increased 663 km2, but it was only contributed by the increasing of human-made wetlands (767 km2), which were mostly caused by economic growth and constructions of human-made hydro-projects in Yangtze Delta. In comparison, natural wetlands, such as tidal flats and marshes, have decreased 163 km2. Land reclamation has changed these natural wetlands into reservoirs, aquaculture ponds and paddy fields. Wetlands in Shanghai and Qidong urban regions were mainly affected by human activities, while wetland variations in Chongming Island were mainly controlled by natural factors such as the upstream discharge, precipitation, diurnal variation of tidal level and long-term sea level rising. The general trend is that the natural wetland was transformed into the human-made wetland, and the human-made wetland was transformed into construction land.

Atmospheric deposition and air-sea gas exchange fluxes of DDT and HCH in the Yangtze River Estuary, East China Sea

NASA Astrophysics Data System (ADS)

Li, Zhongxia; Lin, Tian; Li, Yuanyuan; Jiang, Yuqing; Guo, Zhigang

2017-07-01

The Yangtze River Estuary (YRE) is strongly influenced by the Yangtze River and lies on the pathway of the East Asian Monsoon. This study examined atmospheric deposition and air-sea gas exchange fluxes of dichlorodiphenyltrichloroethane (DDT) and hexachlorocyclohexane (HCH) to determine whether the YRE is a sink or source of selected pesticides at the air-water interface under the influences of river input and atmospheric transport. The air-sea gas exchange of DDT was characterized by net volatilization with a marked difference in its fluxes between summer (140 ng/m2/d) and the other three seasons (12 ng/m2/d), possibly due to the high surface seawater temperatures and larger riverine input in summer. However, there was no obvious seasonal variation in the atmospheric HCH deposition, and the air-sea gas exchange reached equilibrium because of low HCH levels in the air and seawater after the long-term banning of HCH and the degradation. The gas exchange flux of HCH was comparable to the dry and wet deposition fluxes at the air-water interface. This suggests that the influences from the Yangtze River input and East Asian continental outflow on the fate of HCH in the YRE were limited. The gas exchange flux of DDT was about fivefold higher than the total dry and wet deposition fluxes. DDT residues in agricultural soil transported by enhanced riverine runoff were responsible for sustaining such a high net volatilization in summer. Moreover, our results indicated that there were fresh sources of DDT from the local environment to sustain net volatilization throughout the year.

Land claim and loss of tidal flats in the Yangtze Estuary.

PubMed

Chen, Ying; Dong, Jinwei; Xiao, Xiangming; Zhang, Min; Tian, Bo; Zhou, Yunxuan; Li, Bo; Ma, Zhijun

2016-04-01

Tidal flats play a critical role in supporting biodiversity and in providing ecosystem services but are rapidly disappearing because of human activities. The Yangtze Estuary is one of the world's largest alluvial estuaries and is adjacent to the most developed economic zone in China. Using the Yangtze Estuary as a study region, we developed an automatic algorithm to estimate tidal flat areas based on the Land Surface Water Index and the Normalized Difference Vegetation Index. The total area of tidal flats in the Yangtze Estuary has decreased by 36% over the past three decades, including a 38% reduction in saltmarshes and a 31% reduction in barren mudflats. Meanwhile, land claim has accumulated to 1077 km(2), a value that exceeds the area of the remaining tidal flats. We divided the Yangtze Estuary into Shanghai and Jiangsu areas, which differ in riverine sediment supply and tidal flat management patterns. Although land claim has accelerated in both areas, the decline in tidal flat area has been much greater in Jiangsu than in Shanghai because of abundant supplies of sediment and artificial siltation in the latter area. The results highlight the need for better coastal planning and management based on tidal flat dynamics.

Land claim and loss of tidal flats in the Yangtze Estuary

PubMed Central

Chen, Ying; Dong, Jinwei; Xiao, Xiangming; Zhang, Min; Tian, Bo; Zhou, Yunxuan; Li, Bo; Ma, Zhijun

2016-01-01

Tidal flats play a critical role in supporting biodiversity and in providing ecosystem services but are rapidly disappearing because of human activities. The Yangtze Estuary is one of the world’s largest alluvial estuaries and is adjacent to the most developed economic zone in China. Using the Yangtze Estuary as a study region, we developed an automatic algorithm to estimate tidal flat areas based on the Land Surface Water Index and the Normalized Difference Vegetation Index. The total area of tidal flats in the Yangtze Estuary has decreased by 36% over the past three decades, including a 38% reduction in saltmarshes and a 31% reduction in barren mudflats. Meanwhile, land claim has accumulated to 1077 km2, a value that exceeds the area of the remaining tidal flats. We divided the Yangtze Estuary into Shanghai and Jiangsu areas, which differ in riverine sediment supply and tidal flat management patterns. Although land claim has accelerated in both areas, the decline in tidal flat area has been much greater in Jiangsu than in Shanghai because of abundant supplies of sediment and artificial siltation in the latter area. The results highlight the need for better coastal planning and management based on tidal flat dynamics. PMID:27035525

Land claim and loss of tidal flats in the Yangtze Estuary

NASA Astrophysics Data System (ADS)

Chen, Ying; Dong, Jinwei; Xiao, Xiangming; Zhang, Min; Tian, Bo; Zhou, Yunxuan; Li, Bo; Ma, Zhijun

2016-04-01

Tidal flats play a critical role in supporting biodiversity and in providing ecosystem services but are rapidly disappearing because of human activities. The Yangtze Estuary is one of the world’s largest alluvial estuaries and is adjacent to the most developed economic zone in China. Using the Yangtze Estuary as a study region, we developed an automatic algorithm to estimate tidal flat areas based on the Land Surface Water Index and the Normalized Difference Vegetation Index. The total area of tidal flats in the Yangtze Estuary has decreased by 36% over the past three decades, including a 38% reduction in saltmarshes and a 31% reduction in barren mudflats. Meanwhile, land claim has accumulated to 1077 km2, a value that exceeds the area of the remaining tidal flats. We divided the Yangtze Estuary into Shanghai and Jiangsu areas, which differ in riverine sediment supply and tidal flat management patterns. Although land claim has accelerated in both areas, the decline in tidal flat area has been much greater in Jiangsu than in Shanghai because of abundant supplies of sediment and artificial siltation in the latter area. The results highlight the need for better coastal planning and management based on tidal flat dynamics.

Distribution and risk assessment of trace metals in sediments from Yangtze River estuary and Hangzhou Bay, China.

PubMed

Li, Feipeng; Mao, Lingchen; Jia, Yubao; Gu, Zhujun; Shi, Weiling; Chen, Ling; Ye, Hua

2018-01-01

The Yangtze River estuary (YRE) and Hangzhou Bay (HZB) is of environmental significance because of the negative impact from industrial activities and rapid development of aquaculture on the south bank of HZB (SHZB) in recent years. This study investigated the distribution and risk assessments of trace metals (Cr, Cu, Zn, Hg, Pb, and Cd) accumulated in surface sediments by sampling in YRE, outer and south HZB. Copper and Zn concentration (avg. 35.4 and 98.7 mg kg -1 , respectively) in surface sediments were generally higher than the background suggesting a widespread of Cu and Zn in the coastal area of Yangtze River Delta. High concentrations of Cu (~ 42 mg kg -1 ), Zn (~ 111 mg kg -1 ), Cd (~ 0.27 mg kg -1 ), and Hg (~ 0.047 mg kg -1 ) were found in inner estuary of YRE and decreased offshore as a result of terrestrial input and dilution effect of total metal contents by "cleaner" sediments from the adjacent sea. In outer HZB, accumulation of terrestrial derived metal has taken place near the Zhoushan Islands. Increase in sediment metal concentration from the west (inner) to the east (outer) of SHZB gave rise to the input of fine-grained sediments contaminated with metals from outer bay. According the results from geoaccumulation index, nearly 75% of samples from YRE were moderately polluted (1.0 < I geo  < 2.0) by Cd. Cadmium and Hg contributed for 80~90% to the potential ecological risk index in the YRE and HZB, with ~ 72% sites in HZB under moderate risk (150 ≤ RI < 300) especially near Zhoushan Islands.

The capability of estuarine sediments to remove nitrogen: implications for drinking water resource in Yangtze Estuary.

PubMed

Liu, Lin; Wang, Dongqi; Deng, Huanguang; Li, Yangjie; Chang, Siqi; Wu, Zhanlei; Yu, Lin; Hu, Yujie; Yu, Zhongjie; Chen, Zhenlou

2014-09-01

Water in the Yangtze Estuary is fresh most of the year because of the large discharge of Yangtze River. The Qingcaosha Reservoir built on the Changxing Island in the Yangtze Estuary is an estuarine reservoir for drinking water. Denitrification rate in the top 10 cm sediment of the intertidal marshes and bare mudflat of Yangtze Estuarine islands was measured by the acetylene inhibition method. Annual denitrification rate in the top 10 cm of sediment was 23.1 μmol m(-2) h(-1) in marshes (ranged from 7.5 to 42.1 μmol m(-2) h(-1)) and 15.1 μmol m(-2) h(-1) at the mudflat (ranged from 6.6 to 26.5 μmol m(-2) h(-1)). Annual average denitrification rate is higher at mashes than at mudflat, but without a significant difference (p = 0.084, paired t test.). Taking into account the vegetation and water area of the reservoir, a total 1.42 × 10(8) g N could be converted into nitrogen gas (N2) annually by the sediment, which is 97.7 % of the dissolved inorganic nitrogen input through precipitation. Denitrification in reservoir sediment can control the bioavailable nitrogen level of the water body. At the Yangtze estuary, denitrification primarily took place in the top 4 cm of sediment, and there was no significant spatial or temporal variation of denitrification during the year at the marshes and mudflat, which led to no single factor determining the denitrification process but the combined effects of the environmental factors, hydrologic condition, and wetland vegetation.

Process-based morphodynamic modeling of the Yangtze Estuary at a decadal timescale: Controls on estuarine evolution and future trends

NASA Astrophysics Data System (ADS)

Luan, Hua Long; Ding, Ping Xing; Wang, Zheng Bing; Ge, Jian Zhong

2017-08-01

Understanding the decadal morphodynamic evolution of estuaries and deltas and their controls is of vital importance regarding management for estuarine function and sustainable development. This work addresses this issue by applying a process-based model system (Delft3D) to hindcast and then forecast the morphodynamic evolution of the Yangtze Estuary at a decadal timescale. Forced by the river and tides, the model considers sand-mud mixture and the variations of river water discharge and sediment discharge. The morphodynamic model is validated against three periods, i.e., an accretion period (1958-1978), an erosion period (1986-1997) and a recent accretion period with human activities (2002 - 2010). Model results show good performance with respect to spatial erosion and deposition patterns, sediment volume changes, and hypsometry curves. The model reveals quite different behaviors for mud transport between the dry and wet seasons, which is subject to the prescription of river boundary conditions and bed composition. We define six scenarios to project evolution to the year 2030 under decreased river inputs and increased relative sea level. The simulations reveal that overwhelming amount of erosion will likely occur in the inner and mouth bar area of the estuary. Particularly, the mouth zone will shift from net deposition before 2010 to net erosion by 2030, mainly because of decreasing sediment supply. Changes in water discharge have minor effects on the projected trend. Net erosion will be considerable when the sediment supply is extremely low (100 Mt yr- 1) due to the abundance of erodible modern sediment in the Yangtze Estuary. Erosion within the mouth bar area may be unexpected, including the deepening of the tidal inlet at East Chongming mudflat and the formation of a flood channel on the seaward side of Jiuduansha Shoal. Overall, the model results provide valuable information for sustainable delta management under changing conditions for both the Yangtze system

Pollution status of polycyclic aromatic hydrocarbons in surface sediments from the Yangtze River Estuary and its adjacent coastal zone.

PubMed

Wang, Chenglong; Zou, Xinqing; Gao, Jianhua; Zhao, Yifei; Yu, Wenwen; Li, Yali; Song, Qiaochu

2016-11-01

Polycyclic aromatic hydrocarbons (PAHs) are mainly produced by incomplete combustion and are used as indicators of anthropogenic activities on the environment. This study analyses the PAHs level in the Yangtze River Estuary (YRE), an important component of Yangtze River and a developed and populated region in China. Surface sediments were collected from 77 sites at the YRE and its adjacent coastal zone (IACZ) for a comprehensive study of PAHs. Kriging interpolation technology and Positive matrix factorization (PMF) model were applied to explore the spatial distribution and sources of PAHs. Concentrations of 16 PAHs (ΣPAHs) varied from 27.2 ng g(-1) to 621.6 ng g(-1) dry weight, with an average value of 158.2 ng g(-1). Spatially, ΣPAHs exhibited wide fluctuation and exhibited an increasing tendency from north to south. In addition, ΣPAHs exhibited a decreasing trend with increasing distance between the estuary and IACZ. The deposition flux of PAHs indicated that more than 107.8 t a(-1) PAHs was deposited in the study area annually. The results of the PMF model revealed that anthropogenic activities were the main sources of PAHs in the study area. Vehicle emissions and marine engines were the most important sources and accounted for 40.9% of the pollution. Coal combustion, petrogenic sources, and wood combustion were other sources that contributed 23.9%, 23.6%, and 11.5%, respectively. The distribution patterns of PAHs in the YRE and IACZ were influenced by many complicated factors such as sediment grain size, hydrodynamics and so on. Copyright © 2016 Elsevier Ltd. All rights reserved.

[Assessment of resource situation of Collichthys lucidus in coastal waters of the Yangtze estuary].

PubMed

Hu, Yan; Zhang, Tao; Yang, Gang; Zhao, Feng; Hou, Jun-li; Zhang, Long-zhen; Zhuang, Ping

2015-09-01

In order to assess the resource status of Collichthys lucidus in coastal waters of Yangtze estuary, the growth and population parameters were studied by the length frequency distribution method based on the bottom trawl investigation data from 2012 to 2013. Von Bertalanffy growth parameters were calculated by using the ELEFAN module in FiSAT II software while the natural mortality rate (M) was estimated via Pauly's empirical equation. Besides, the Beverton-Holt dynamic model was developed to predict the variation trend of C. lucidus resource in coastal waters of Yangtze estuary. The results showed that in 2012-2013, a total of 4201 samples of C. lucidus with body lengths ranging from 18 to 155 mm were collected from the coastal waters of Yangtze estuary. The growth parameter (K) and limit length (L.) were 1.1 and 162.75 mm while the total mortality rate (Z), the natural mortality rate (M) and the fishing mortality rate (F) were 4.040, 1.683 and 2.357, respectively. Moreover, the current exploitation (E) of C. lucidus in coastal waters of Yangtze estuary was 0.583 per year, which was larger than Fopt (0.5). Corresponding to the average stock of 576.02 t, the resource amount of C. lucidus reached up to 1.33 x 10(8) individuals. These indicated that C. lucidus has been overfished in Yangtze estuary area.

[Nutrients Input Characteristics of the Yangtze River and Wangyu River During the "Water Transfers on Lake Taihu from the Yangtze River"].

PubMed

Pan, Xiao-xue; Ma, Ying-qun; Qin, Yan-wen; Zou, Hua

2015-08-01

Overall 20 surface water samples were collected from the Yangtze River, the Wangyu River and the Gonghu Bay (Lake Taihu) to clarify the pollution characteristics of nitrogen and phosphorus during 2 sample stages of "Water Transfers on Lake Taihu from the Yangtze River" in August and December of 2013 respectively. The results showed that the mass concentrations of NO2- -N, NO3- -N, NH4+ -N and TN in the Gonghu Bay were lower than those of the Yangtze River and Wangyu River during the 2 water transfer processes. However, there was higher level of DON content in the Gonghu Bay than that of the Yangtze River and Wangyu River. The percentages of various N species showed that NO3- -N was the major N species in the Yangtze River and Wangyu River during the 2 water transfer processes. TP contents in samples collected from the Yangtze River displayed a constant trend compared with the Wangyu River. However, the percentages of various P species were different with each other during the 2 water transfer processes. Mass concentrations of DON and TP in surface water in August were higher than those in December and the contents of NO3- -N and TDP were lower in August than those in December. In general, NO3- -N and TPP were the main N and P species in Wangyu River from the Yangtze River. NO3- -N, PO4(3-) -P and TPP were the main N and P species in Gonghu Bay from Wangyu River during the 2 water transfer processes.

Gross Nitrogen Mineralization in Surface Sediments of the Yangtze Estuary

PubMed Central

Liu, Min; Li, Xiaofei; Yin, Guoyu; Zheng, Yanling; Deng, Fengyu

2016-01-01

Nitrogen mineralization is a key biogeochemical process transforming organic nitrogen to inorganic nitrogen in estuarine and coastal sediments. Although sedimentary nitrogen mineralization is an important internal driver for aquatic eutrophication, few studies have investigated sedimentary nitrogen mineralization in these environments. Sediment-slurry incubation experiments combined with 15N isotope dilution technique were conducted to quantify the potential rates of nitrogen mineralization in surface sediments of the Yangtze Estuary. The gross nitrogen mineralization (GNM) rates ranged from 0.02 to 5.13 mg N kg-1 d-1 in surface sediments of the study area. The GNM rates were generally higher in summer than in winter, and the relative high rates were detected mainly at sites near the north branch and frontal edge of this estuary. The spatial and temporal distributions of GNM rates were observed to depend largely on temperature, salinity, sedimentary organic carbon and nitrogen contents, and extracellular enzyme (urease and L-glutaminase) activities. The total mineralized nitrogen in the sediments of the Yangtze Estuary was estimated to be about 6.17 × 105 t N yr-1, and approximately 37% of it was retained in the estuary. Assuming the retained mineralized nitrogen is totally released from the sediments into the water column, which contributed 12–15% of total dissolved inorganic nitrogen (DIN) sources in this study area. This result indicated that the mineralization process is a significant internal nitrogen source for the overlying water of the Yangtze Estuary, and thus may contribute to the estuarine and coastal eutrophication. PMID:26991904

Spatial-temporal distribution and risk assessment of mercury in different fractions in surface sediments from the Yangtze River estuary.

PubMed

Wang, Qingrui; Liu, Ruimin; Men, Cong; Xu, Fei; Guo, Lijia; Shen, Zhenyao

2017-11-15

The temporal and spatial distributions of mercury in different fractions and its potential ecological risk were investigated in sediments from the Yangtze River estuary (YRE) by analyzing data collected from the study area. The results showed that mercury in the organic and residual fractions had dominant proportions, from 15.2% to 48.52% and from 45.96% to 81.59%, respectively. The fractions were more susceptible to seasonal changes than other fractions. Higher proportions of mercury in organic fraction were found in wet seasons; the opposite was true for mercury in residual fraction. With respect to the spatial distribution, the concentration mercury in exchangeable, carbonate and Fe-Mn oxide fractions showed a decreasing trend from the inner estuary to the outer estuary, but no obvious trends were found in the distributions of mercury in the organic and residual fractions. The risk assessment code (RAC) was used to evaluate the potential ecological risk in the study area based on the proportions of exchangeable and carbonate fractions. The average RAC values during the four periods were 6.00%, 2.20%, 2.83%, and 0.61%. Although these values show that the risk in the study area is generally low, the distribution of RAC values indicates that the inner estuary has a medium risk, with a value up to 10%. Copyright © 2017 Elsevier Ltd. All rights reserved.

Assessment of the Mutagenicity of Sediments from Yangtze River Estuary Using Salmonella Typhimurium/Microsome Assay

PubMed Central

Liu, Li; Chen, Ling; Floehr, Tilman; Xiao, Hongxia; Bluhm, Kerstin; Hollert, Henner; Wu, Lingling

2015-01-01

Sediments in estuaries are of important environmental concern because they may act as pollution sinks and sources to the overlying water body. These sediments can be accumulated by benthic organisms. This study assessed the mutagenic potential of sediment extracts from the Yangtze River estuary by using the Ames fluctuation assay with the Salmonella typhimurium his (−) strain TA98 (frameshift mutagen indicator) and TA100 (baseshift mutagen indicator). Most of the sediment samples were mutagenic to the strain TA98, regardless of the presence or absence of exogenous metabolic activation (S9 induction by β-naphthoflavone/phenobarbital). However, none of the samples were mutagenic to the strain TA100. Thus, the mutagenicity pattern was mainly frameshift mutation, and the responsible toxicants were both direct (without S9 mix) and indirect (with S9 mix) mutagens. The mutagenicity of the sediment extracts increased when S9 was added. Chemical analysis showed a poor correlation between the content of priority polycyclic aromatic hydrocarbons and the detected mutagenicity in each sample. The concept of effect-directed analysis was used to analyze possible compounds responsible for the detected mutagenic effects. With regard to the mutagenicity of sediment fractions, non-polar compounds as well as weakly and moderately polar compounds played a main role. Further investigations should be conducted to identify the responsible components. PMID:26606056

Tidal impacts on the subtidal flow division at the main bifurcation in the Yangtze River Delta

NASA Astrophysics Data System (ADS)

Zhang, Wei; Feng, Haochuan; Hoitink, A. J. F.; Zhu, Yuliang; Gong, Fei; Zheng, Jinhai

2017-09-01

Flow division at bifurcations in the Yangtze Estuary has received ample attention, since it may control the pathways of terrestrial sediments over downstream river branches including the 12.5 m Deepwater Navigation channel. While some efforts have been made to interpret flow division at the bifurcations of the Yangtze Estuary, little attention has been paid to the role of tides. Flow division at estuarine bifurcations is made complicated by tides that propagate from the outlet of the tidal channels into the delta. To quantify the tidal influence on the distribution of river discharge, and more generally, to understand the mechanisms governing the subtidal flow division at the tidally affected bifurcation in the Yangtze River Delta, a two-dimensional hydrodynamic model is employed. In this model, the landward boundary is chosen beyond the tidal limit, where the tidal motion has faded out entirely. The seaward boundary is chosen such that the river discharge does not influence the water level. Subtidal discharges are decomposed using the method of factor separation, to distinguish between the effects of tides, river discharge and river-tide interactions on the subtidal flow division. Results indicate that tides modify the river discharge distribution over distributary channels in the Yangtze River Delta, particularly in the dry season. A significant difference in the subtidal flow division during spring tide and neap tide shows that the tidally averaged flow division over the distributaries in the delta greatly depends on tidal amplitude. By varying the river discharge at the landward boundary and amplitudes and phases of the principal tidal constituents at the seaward boundary of the established model, the sensitivities of the subtidal flow division to the river discharge and tidal amplitude variation were investigated in detail. Generally, the tidal impacts on the subtidal flow division are around 12% to 22%, with river discharge varying from 30,000 m3s-1 to 20

Seasonal variation, flux estimation, and source analysis of dissolved emerging organic contaminants in the Yangtze Estuary, China.

PubMed

Zhao, Heng; Cao, Zhen; Liu, Xue; Zhan, Yi; Zhang, Jing; Xiao, Xi; Yang, Yi; Zhou, Junliang; Xu, Jiang

2017-12-15

The occurrence and seasonal variation of 24 dissolved emerging organic contaminants in the Yangtze Estuary were studied, including 12 non-antibiotic pharmaceuticals, seven sulfonamides, two macrolides and three chloramphenicols. Sulfadiazine, erythromycin, thiamphenicol and paracetamol were the primary contaminants in sulfonamides, macrolides, chloramphenicols and non-antibiotic pharmaceutical groups, respectively. Compared to the concentrations at Datong, chloramphenicols at Xuliujing were significantly higher in autumn and winter, while macrolides were lower in spring. Based on the flux estimation, approximately 37.1 tons of sulfonamides, 17.4 tons of macrolides, 79.2 tons of chloramphenicols and 14.1 tons of non-antibiotic pharmaceuticals were discharged into the Yangtze Estuary from June 2013 to May 2014. However, the total flux from the Huangpu River only represented 5% of the total. The pharmaceutical sources were speculated on by analyzing the seasonal variations in pharmaceutical concentrations and fluxes at various sites. Both environmental and social factors might affect the fluxes. Copyright © 2017 Elsevier Ltd. All rights reserved.

Flux and fate of Yangtze River sediment delivered to the East China Sea

NASA Astrophysics Data System (ADS)

Liu, J. P.; Xu, K. H.; Li, A. C.; Milliman, J. D.; Velozzi, D. M.; Xiao, S. B.; Yang, Z. S.

2007-03-01

Numerous cores and dating show the Yangtze River has accumulated about 1.16 × 10 12 t sediment in its delta plain and proximal subaqueous delta during Holocene. High-resolution seismic profiling and coring in the southern East China Sea during 2003 and 2004 cruises has revealed an elongated (˜ 800 km) distal subaqueous mud wedge extending from the Yangtze River mouth southward off the Zhejiang and Fujian coasts into the Taiwan Strait. Overlying what appears to be a transgressive sand layer, this distal clinoform thins offshore, from ˜ 40 m thickness between the 20 and 30 m water depth to < 1-2 m between 60 and 90 m water depth, corresponding to an across shelf distance of less than 100 km. Total volume of this distal mud wedge is about 4.5 × 10 11 m 3, equivalent to ˜ 5.4 × 10 11 t of sediment. Most of the sediment in this mud wedge comes from the Yangtze River, with some input presumably coming from local smaller rivers. Thus, the total Yangtze-derived sediments accumulated in its deltaic system and East China Sea inner shelf have amounted to about 1.7 × 10 12 t. Preliminary analyses suggest this longshore and across-shelf transported clinoform mainly formed in the past 7000 yrs after postglacial sea level reached its mid-Holocene highstand, and after re-intensification of the Chinese longshore current system. Sedimentation accumulation apparently increased around 2000 yrs BP, reflecting the evolution of the Yangtze estuary and increased land erosion due to human activities, such as farming and deforestation. The southward-flowing China Coastal Current, the northward-flowing Taiwan Warm Current, and the Kuroshio Current appear to have played critical roles in transporting and trapping most of Yangtze-derived materials in the inner shelf, and hence preventing the sediment escape into the deep ocean.

[Optical characteristics of colored dissolved organic material (CDOM) in Yangtze Estuary].

PubMed

Zhu, Wei-Jian; Shen, Fang; Hong, Guan-Lin

2010-10-01

Absorption property of colored dissolved organic material (CDOM) is one of the most important contents to remote sensing of ocean color in estuarine and coastal areas. In this study, the optical properties and mixing behavior of CDOM in surface water of Yangtze Estuary were discussed according to the two surveys in August of 2008 and May of 2009. Based on the research, the absorption coefficient and spectral slope were discussed. It was found that in summer of 2008 CDOM absorption coefficients at 440 nm [a(g) (440)], ranged from 0.20 m(-1) to 0.73 m(-1), while the coefficients in 2009 varied between 0.20 m(-1) and 0.77 m(-1). Statistics showed that the power function model fitted the best in the regression analysis of CDOM absorption spectral. The spectral slopes (S(g2)) of CDOM calculated by the power function model ranged from 5.10 to 7.90 in Summer of 2008 and from 2.95 to 6.11 in Spring of 2009. The highest absorption coefficients of two cruises appeared both in the south passage of the Yangtze Estuary. The absorption coefficient in surfer water was observed varied tremendously in the estuary and the offshore area. And the main reason is affected by the turbidity maximum zone. It is observed that the absorption coefficients of CDOM tended to a homogeneous distribution whilst the layers of water mixed tempestuously, but otherwise it always showed a conservative mixing behavior. Because of the frequent mixture, there is not assured correlativity between S(g2) and a(g) (440). In the offshore area of Yangtze Estuary, the effecting of local production cannot be negligent, which differed from the estuary area. Yet when the hydrological environment was relatively stable, the negative relationship between them was very clear. In conclusion, the optical properties and mixing behavior of CDOM had showed tremendous different characteristics from inside the estuary to outside the estuary because of the influence of complex physical, chemical and hydrology conditions.

The Recent Microrelief Features of the Yangtze Estuary

NASA Astrophysics Data System (ADS)

Wu, S. H.

2016-02-01

Based on the bedforms date were made in the Yangtze estuary, China, during January 2010 and July 2015 with the acoustic multi-beam bathymetric and shallow sediment profiler and surface sediment samples collected recently, the microrelief features of the Yangtze Estuary under the human interference recently is studied. Results show that in addition to four types of common microrelief (smooth bedfloors , sandwaves, hollow and gully), but also there are two types of microrelief under the human interference (sand and dredging mark).Restricted by the nature of sediment, sand waves exist only in the local region of the South Channel, the North Channel the South Passage and the Hengsha passage whose main types of the surface sediment was fine sand. Under the combined effect of a series of large-scale engineering with watershed and estuary, the upper reach of North Channel, the Hengsha passage, the upper reach of south Channel and the upper reach of the South passage are subject to different degrees of erosion recently, so there are varying degrees of erosive microrelief (hollow and gully). Due to dredging engineering and artificial disordered mining, there are a huge range of dredging mark in the lower reach of South Channel, Yuanyuansha channel and North passage and there are a degree of sand in the main channel of south side of Ruifengsha.

Absorption and fluorescence characteristics of chromophoric dissolved organic matter in the Yangtze Estuary.

PubMed

Sun, Qiyuan; Wang, Chao; Wang, Peifang; Hou, Jun; Ao, Yanhui

2014-03-01

The Yangtze Estuary is heavily influenced by coast-continent geochemical processes and anthropogenic activity; thus, the source and distribution of chromophoric dissolved organic matter (CDOM) in the estuary are strongly impacted by these processes. Here, a series of samples were collected from across the Yangtze Estuary to investigate the source and spatial dynamics of CDOM and its components throughout the system. Three indices (a(355), spectral slope, and fluorescence) were then calculated and interpreted. The results indicated that the distribution of CDOM was dominated by allochthonous input, conservative mixing, and phase transfer. The contribution of biogenic CDOM to total CDOM increased with salinity, and three individual CDOM components were identified upon fluorescence excitation emission matrix spectroscopy and parallel factor analysis of the water samples: C1, corresponding to humic substance-like CDOM, C2, corresponding to tryptophan-like CDOM, and C3, corresponding to tyrosine-like CDOM. C1 primarily originated from a terrestrial source, C2 had widespread origins, none of which played a dominant role, and C3 mainly originated from allochthonous input in the medium salinity area. Unexpectedly, no marine humic-like component was found in the surface water of the Yangtze Estuary, possibly because turbidity decreased the depth of sunlight penetration, limiting production of this component.

Spatial distribution and pollution evaluation of heavy metals in Yangtze estuary sediment.

PubMed

Liu, Ruimin; Men, Cong; Liu, Yongyan; Yu, Wenwen; Xu, Fei; Shen, Zhenyao

2016-09-15

To analyze the spatial distribution patterns and ecological risks of heavy metals, 30 sediment samples were taken in the Yangtze River Estuary (YRE) in May 2011. The content of Al, As, Cr, Cu, Fe, Mn, Ni and Pb increased as follows: inner-region<river mouthriver mouth of the south branch of YRE. In Tucker 3, considering the fractions of metals, Mn turned to be the severest pollutant and As did not contribute too much to the contamination of the YRE. That was most probably because that Mn was closely related to the carbonate-associated (CARB) and As was related to organic-associated (OM) which is more stable than CARB. The fractions played an important role in the contamination assessment of heavy metals. Copyright © 2016 Elsevier Ltd. All rights reserved.

[Estuary health assessment using a benthic-index of biotic integrity in Yangtze Estuary and its adjacent waters].

PubMed

Zhou, Xiao-wei; Wang, Li-ping; Zheng, Bing-hui; Liu, Lu-san; Fu, Qing

2009-01-01

A benthic index of biotic integrity (B-IBI) was developed for application in estuaries health assessment of the Yangtze Estuary and its adjacent waters. Benthic macro-invertebrate samples were collected from 41 stream sites (13 non-degraded stations and 28 degraded stations) in the Yangtze Estuary and its adjacent waters in July, 2005. The analyses of the range of index value distribution, Pearson correlation and judgment ability were performed on fourteen candidate metrics. Six biological metrics were selected for the establishment of B-IBI, which were Shannon-Wiener index, the species number, total density, total biomass, Carapace Animals density percentage and Echinoderms density percentage. B-IBI was obtained by sum up all these indices after which were transformed into a uniform score by using the ratio scoring method. Base on 50 percentile of B-IBI value in reference sites, the criteria of health ranking was determined. The proposed criteria of benthic-index of biotic integrity were as follows: B-IBI > 2.48 was regarded as health, 1.86-2.48 sub-health, 1.24-1.86 fair, 0.62-1.24 poor, and B-IBI < 0.62 very poor. Assessing with these criteria, the results showed that among the 41 sites in Yangtze Estuary and its adjacent waters, 7 sites were health, 2 sites were sub-health, 8 sites were fair, 8 sites were poor and 16 sites were very poor. An independent data set sampled in June of 2006 was used to validate the index, the results indicated that final combined index correctly classified 89% of stations in the validation data set.

Identification and apportionment of hazardous elements in the sediments in the Yangtze River estuary.

PubMed

Wang, Jiawei; Liu, Ruimin; Wang, Haotian; Yu, Wenwen; Xu, Fei; Shen, Zhenyao

2015-12-01

In this study, positive matrix factorization (PMF) and principal components analysis (PCA) were combined to identify and apportion pollution-based sources of hazardous elements in the surface sediments in the Yangtze River estuary (YRE). Source identification analysis indicated that PC1, including Al, Fe, Mn, Cr, Ni, As, Cu, and Zn, can be defined as a sewage component; PC2, including Pb and Sb, can be considered as an atmospheric deposition component; and PC3, containing Cd and Hg, can be considered as an agricultural nonpoint component. To better identify the sources and quantitatively apportion the concentrations to their sources, eight sources were identified with PMF: agricultural/industrial sewage mixed (18.6 %), mining wastewater (15.9 %), agricultural fertilizer (14.5 %), atmospheric deposition (12.8 %), agricultural nonpoint (10.6 %), industrial wastewater (9.8 %), marine activity (9.0 %), and nickel plating industry (8.8 %). Overall, the hazardous element content seems to be more connected to anthropogenic activity instead of natural sources. The PCA results laid the foundation for the PMF analysis by providing a general classification of sources. PMF resolves more factors with a higher explained variance than PCA; PMF provided both the internal analysis and the quantitative analysis. The combination of the two methods can provide more reasonable and reliable results.

[Effect of suspended silt from dredging at Yangtze estuary on Brachionus plicatilis].

PubMed

Wang, Jinqui; Xu, Zhaoli; Shi, Chun; Chen, Yaqu

2002-07-01

The effect of suspended silt from dredging at Yangtze estuary on Brachionus plicatilis was investigated by clonal culture (to construct life table) and population accumulative culture. The intrinsic increasing rate of the rotifer population was greatly reduced under different concentrations (1, 3, 5, 7 and 9 mg.ml-1) of silt, from 29.6% to 64.1%, and to a maximum of 130.0%. The suspended silt affected population survival rate, rather than its reproduction rate. In accumulative culture, the densities of female, males, parthenogenetic eggs, and resting eggs in the population were not affected by silt. It was concluded that the presence of suspended silt should have a certain negative influence on the rotifer population in dredging Yangtze estuary.

Anthropogenic sea level rise and adaptation in the Yangtze estuary

NASA Astrophysics Data System (ADS)

Cheng, H.; Chen, J.; Chen, Z.; Ruan, R.; Xu, G.; Zeng, G.; Zhu, J.; Dai, Z.; Gu, S.; Zhang, X.; Wang, H.

2016-02-01

Sea level rise is a major projected threat of climate change. There are regional variations in sea level changes, depending on both naturally the tectonic subsidence, geomorphology, naturally changing river inputs and anthropogenic driven forces as artificial reservoir water impoundment within the watershed and urban land subsidence driven by ground water depletion in the river delta. Little is known on regional sea level fall in response to the channel erosion due to the sediment discharge decline by reservoir interception in the upstream watershed, and water level rise driven by anthropogenic measures as the land reclamation, deep waterway regulation and fresh water reservoir construction to the sea level change in estuaries. Changing coastal cities are situated in the delta regions expected to be threatened in various degrees. Shanghai belongs to those cities. Here we show that the anthropogenic driven sea level rise in the Yangtze estuary from the point of view of the continuous hydrodynamic system consisted of river catchment, estuary and coastal sea. Land subsidence is cited as 4 mm/a (2011-2030). Scour depth of the estuarine channel by upstream engineering as Three Gauge Dam is estimated at 2-10 cm (2011-2030). The rise of water level by deep waterway and land reclamation is estimated at 8-10 cm (2011-2030). The relative sea level rise will be speculated about 10 -16 cm (2011-2030), which these anthropogenic sea level changes will be imposed into the absolute sea level rise 2 mm/a and tectonic subsidence 1 mm/a measured in 1990s. The action guideline to the sea level rise strategy in the Shanghai city have been proposed to the Shanghai government as (1) recent actions (2012-2015) to upgrade the city water supply and drainage engineering and protective engineering; (2) interim actions (2016-2020) to improve sea level monitoring and early warning system, and then the special, city, regional planning considering sea level rise; (3) long term actions (2021

Trend and dynamic cause of sediment particle size on the adjacent continental shelf of the Yangtze Estuary

NASA Astrophysics Data System (ADS)

Yang, Yun-ping; Zhang, Ming-jin; Li, Yi-tian; Fan, Yong-yang

2016-12-01

Based on the measured data in recent 20 years, the variation trends of the median grain size of the surface sediment, the sand-silt boundary and the mud area on the adjacent continental shelf of the Yangtze Estuary were analyzed in depth, and the effects of natural mechanism and human activities were discussed. The results show that: (1) In recent years (2006-2013), the median grain size of sediment and the distribution pattern of grouped sediments in the adjacent continental shelf area to the Yangtze Estuary have presented no obvious change compared with those before 2006; (2) The median diameter of the surface sediment in the continental shelf area displayed a coarsening trend with the decrease of sediment discharge from the basin and the drop in suspended sediment concentration in the shore area; (3) In 2004-2007, the sand-silt boundary in the north part (31°30'N) of the continental shelf area presented no significant changes, while that in the south part (31°30'S) moved inwards; In 2008-2013, both the sand-silt boundaries in the north and south parts of the continental shelf area moved inwards, mainly due to the fact that in the dry season, a relatively enhanced hydrodynamic force of the tides was generated in the Yangtze River, as well as a decreased suspended sediment concentration and a flow along the banks in North Jiangsu; (4) The mud area where the maximum deposition rate is found in the Yangtze Estuary, tends to shrink due to the drop in sediment discharge from the basin, and the decrease in suspended sediment concentration in the shore area and erosion in the delta. Moreover, it tended to shift to the south at the same time because the implement of the training works on the deep-water channel of the North Passage changed the split ratio between the North and South Passages with an increase in the power of the discharged runoff in the South Passage.

Distribution of heavy metals and environmental assessment of surface sediment of typical estuaries in eastern China.

PubMed

Bi, Shipu; Yang, Yuan; Xu, Chengfen; Zhang, Yong; Zhang, Xiaobo; Zhang, Xianrong

2017-08-15

Estuary sediment is a major pollutant enrichment medium and is an important biological habitat. This sediment has attracted the attention of the marine environmental scientists because it is a more stable and effective medium than water for monitoring regional environmental quality conditions and trends. Based on a large amount of measurement data, we analyzed the concentrations, distribution, and sources of seven heavy metals (As, Cd, Cr, Cu, Hg, Pb, and Zn) in the surface sediment of typical estuaries that empty into the sea in eastern China: the Liaohe River Estuary, Yellow River Estuary, Yangtze River Estuary, Minjiang River Estuary, and Pearl River Estuary. The heavy metal concentrations in the sediments vary considerably from one estuary to the next. The Liaohe River Estuary sediment contains elevated levels of Cd, Hg, and Zn. The Yellow River Estuary sediment contains elevated levels of As. The sediments in the Yangtze River and Minjiang River estuaries contain elevated levels of Cd and Cu and of Pb and Zn, respectively. The sediment in the Pearl River Estuary contains elevated levels of all seven heavy metals. We used the Nemerow index method to assess the environment quality. The heavy metal pollution in the Liaohe River and Pearl River estuaries is more severe than that in the other estuaries. Additional work indicates that the heavy metal pollution in the Liaohe River and Pearl River estuaries is caused mainly by human activity. Copyright © 2017. Published by Elsevier Ltd.

Characterization and spacial distribution variability of chromophoric dissolved organic matter (CDOM) in the Yangtze Estuary.

PubMed

Wang, Ying; Zhang, Di; Shen, Zhenyao; Chen, Jing; Feng, Chenghong

2014-01-01

The spatial characteristics and the quantity and quality of the chromophoric dissolved organic matter (CDOM) in the Yangtze Estuary, based on the abundance, degree of humification and sources, were studied using 3D fluorescence excitation emission matrix spectra (F-EEMs) with parallel factor and principal component analysis (PARAFAC-PCA). The results indicated that the CDOM abundance decreased and the aromaticity increased from the upstream to the downstream areas of the estuary. Higher CDOM abundance and degrees of humification were observed in the pore water than that in the surface and bottom waters. Two humic-like components (C1 and C3) and one tryptophan-like component (C2) were identified using the PARAFAC model. The separation of the samples by PCA highlighted the differences in the DOM properties. Components C1 and C3 concurrently displayed positive factor 1 loadings with nearly zero factor 2 loadings, while C2 showed highly positive factor 2 loadings. The C1 and C3 were very similar and exhibited a direct relationship with A355 and DOC. The CDOM in the pore water increased along the river to the coastal area, which was mainly influenced by C1 and C3 and was significantly derived from sediment remineralization and deposition from the inflow of the Yangtze River. The CDOM in the surface and bottom waters was dominated by C2, especially in the inflows of multiple tributaries that were affected by intensive anthropogenic activities. The microbial degradation of exogenous wastes from the tributary inputs and shoreside discharges were dominant sources of the CDOM in the surface and bottom waters. Copyright © 2013 Elsevier Ltd. All rights reserved.

Ichthyoplankton assemblage structure of springs in the Yangtze Estuary revealed by biological and environmental visions.

PubMed

Zhang, Hui; Xian, Weiwei; Liu, Shude

2015-01-01

The ichthyoplankton assemblage structure in the Yangtze Estuary was analyzed based on four springs in 1999, 2001, 2004 and 2007 in order to provide detailed characterizations of the ichthyoplankton assemblage in springs, examine the long-term dynamics of spring ichthyoplankton assemblages, and evaluate the influence of environmental factors on the spatial distribution and inter-annual variations of ichthyoplankton assemblages associated with the Yangtze Estuary. Forty-two ichthyoplankton species belonging to 23 families were collected. Engraulidae was the most abundant family, including six species and comprising 67.91% of the total catch. Only four species (Coilia mystus, Engraulis japonicus, Trachidermis fasciatus and Allanetta bleekeri) could be considered dominant, accounting for 88.70% of total abundance. The structure of the ichthyoplankton spring assemblage persisted on an annual basis, with the dominant species reappearing consistently even though their abundance fluctuated from year to year. This inter-annual variation probably reflects variable environmental conditions influenced by jellyfish blooms, declining river flow, and overfishing. Canonical correspondence analysis indicated aspatial structure of the ichthyoplankton assemblage in three areas: (1) an inner assemblage dominated by C. mystus; (2) a central assemblage dominated by A. bleekeri and T. fasciatus; and (3) a shelf assemblage featuring E. japonicus. The observed ichthyoplankton assemblage structure appears to be strongly influenced by depth, salinity and suspended particulate matter gradients.

Ichthyoplankton assemblage structure of springs in the Yangtze Estuary revealed by biological and environmental visions

PubMed Central

Zhang, Hui; Liu, Shude

2015-01-01

The ichthyoplankton assemblage structure in the Yangtze Estuary was analyzed based on four springs in 1999, 2001, 2004 and 2007 in order to provide detailed characterizations of the ichthyoplankton assemblage in springs, examine the long-term dynamics of spring ichthyoplankton assemblages, and evaluate the influence of environmental factors on the spatial distribution and inter-annual variations of ichthyoplankton assemblages associated with the Yangtze Estuary. Forty-two ichthyoplankton species belonging to 23 families were collected. Engraulidae was the most abundant family, including six species and comprising 67.91% of the total catch. Only four species (Coilia mystus, Engraulis japonicus, Trachidermis fasciatus and Allanetta bleekeri) could be considered dominant, accounting for 88.70% of total abundance. The structure of the ichthyoplankton spring assemblage persisted on an annual basis, with the dominant species reappearing consistently even though their abundance fluctuated from year to year. This inter-annual variation probably reflects variable environmental conditions influenced by jellyfish blooms, declining river flow, and overfishing. Canonical correspondence analysis indicated aspatial structure of the ichthyoplankton assemblage in three areas: (1) an inner assemblage dominated by C. mystus; (2) a central assemblage dominated by A. bleekeri and T. fasciatus; and (3) a shelf assemblage featuring E. japonicus. The observed ichthyoplankton assemblage structure appears to be strongly influenced by depth, salinity and suspended particulate matter gradients. PMID:26312180

Variations in early life history traits of Japanese anchovy Engraulis japonicus in the Yangtze River Estuary.

PubMed

Liu, Chunlong; Xian, Weiwei; Liu, Shude; Chen, Yifeng

2018-01-01

Resources of Japanese anchovy ( Engraulis japonicus Temminck & Schlegel, 1846) are undergoing dramatic recessions in China as the consequence of intensifying anthropogenic activities. Elucidating the influences of local-scale environmental factors on early life history traits is of great importance to design strategies conserving and restoring the declining anchovy resources. In this research, we studied hatching date and early growth of anchovy in the Yangtze River Estuary (YRE) using information obtained from otolith microstructure. Onset of hatching season and growth rates of anchovy was compared to populations in Japan and Taiwan. In YRE, the hatching date of anchovy ranged from February 26th to April 6th and mean growth rate ranged from 0.27 to 0.77 mm/d. Anchovies hatching later had higher growth rates than individuals hatching earlier before the 25th day. Among populations, hatching onsets of anchovy from the higher latitude were later than populations in the lower latitude, and growth rates of anchovy in YRE were much lower than populations in Japan and Taiwan. Variations in hatching onsets and early growth patterns of anchovy thus provide important knowledge on understanding the adaptation of anchovy in YRE and designing management strategies on conserving China's anchovy resources.

Assessing dissolved inorganic nitrogen flux in the Yangtze River, China: Sources and scenarios

NASA Astrophysics Data System (ADS)

Xu, Hao; Chen, Zhongyuan; Finlayson, Brian; Webber, Michael; Wu, Xiaodan; Li, Maotian; Chen, Jing; Wei, Taoyuan; Barnett, Jon; Wang, Mark

2013-07-01

This study gives a thorough assessment of the occurrences of dissolved inorganic nitrogen (DIN) in the Yangtze River in the past half century. The results have shown that nitrogen fertilizer, a major DIN source, has been replaced by domestic sewage in the last decade, which has dramatically driven up DIN loads in the Yangtze. DIN concentrations showed a rapid increase from < 0.5 mg L- 1 in the 1960s to nearly 1.5 mg L- 1 at the end of the 1990s. Since then DIN has remained steady at ca. 1.6-1.8 mg L- 1. A significant relationship between the historical DIN record at the downstream gauging station (Datong) and nitrogen (N) sources in the Yangtze River basin is established using principal components analysis. This allows us to apportion DIN loads for the year 2007 (the most recent year of measured DIN data available) to various N sources, listed here in order of weight: sewage (0.391 million tons); atmosphere (0.358 million tons); manure (0.318 million tons), N-fertilizer (0.271 million tons). Therefore, we estimated that a DIN load of 1.339 × 106 t was delivered to the lower Yangtze and its estuarine water in that year. We established scenarios to predict DIN concentrations in the lower Yangtze at 10 year intervals to 2050. For a dry year (20,000 m3 s- 1) DIN concentrations would range from 2.2-3.0 mg L- 1 for 2020-2050. This far exceeds the 2.0 mg L- 1 defined on the Chinese National Scale as the worst class for potable source water. The scenario results suggest that upgrading the sewage treatment systems throughout the basin will be an effective way to help reduce DIN concentrations to less than 2.0 mg L- 1 in the lower Yangtze. This would save the Shanghai megacity from the increasing threat of heavily polluted water sources, where > 23 million people are at present dependent on the Yangtze estuary for 70% of their freshwater intake.

Adaptation of Arabidopsis thaliana to the Yangtze River basin.

PubMed

Zou, Yu-Pan; Hou, Xing-Hui; Wu, Qiong; Chen, Jia-Fu; Li, Zi-Wen; Han, Ting-Shen; Niu, Xiao-Min; Yang, Li; Xu, Yong-Chao; Zhang, Jie; Zhang, Fu-Min; Tan, Dunyan; Tian, Zhixi; Gu, Hongya; Guo, Ya-Long

2017-12-28

Organisms need to adapt to keep pace with a changing environment. Examining recent range expansion aids our understanding of how organisms evolve to overcome environmental constraints. However, how organisms adapt to climate changes is a crucial biological question that is still largely unanswered. The plant Arabidopsis thaliana is an excellent system to study this fundamental question. Its origin is in the Iberian Peninsula and North Africa, but it has spread to the Far East, including the most south-eastern edge of its native habitats, the Yangtze River basin, where the climate is very different. We sequenced 118 A. thaliana strains from the region surrounding the Yangtze River basin. We found that the Yangtze River basin population is a unique population and diverged about 61,409 years ago, with gene flows occurring at two different time points, followed by a population dispersion into the Yangtze River basin in the last few thousands of years. Positive selection analyses revealed that biological regulation processes, such as flowering time, immune and defense response processes could be correlated with the adaptation event. In particular, we found that the flowering time gene SVP has contributed to A. thaliana adaptation to the Yangtze River basin based on genetic mapping. A. thaliana adapted to the Yangtze River basin habitat by promoting the onset of flowering, a finding that sheds light on how a species can adapt to locales with very different climates.

Photobleaching of chromophoric dissolved organic matter (CDOM) in the Yangtze River estuary: kinetics and effects of temperature, pH, and salinity.

PubMed

Song, Guisheng; Li, Yijie; Hu, Suzheng; Li, Guiju; Zhao, Ruihua; Sun, Xin; Xie, Huixiang

2017-06-21

The kinetics and temperature-, pH- and salinity-dependences of photobleaching of chromophoric dissolved organic matter (CDOM) in the Yangtze River estuary (YRE) were evaluated using laboratory solar-simulated irradiation and compared to those of Suwannee River humic substances (SRHSs). Nearly all CDOM in water at the head of the estuary (headwater herein) was photobleachable in both summer and winter, while significant fractions of CDOM (13-29%) were resistant to photobleaching in saltier waters. The photobleaching rate constant in the headwater was 25% higher in summer than that in winter. The absorbed photon-based photobleaching efficiency (PE) increased with temperature following the linear Arrhenius equation. For a 20 °C increase in temperature, PE increased by ∼45% in the headwater and by 70-81% in the saltier waters. PE for YRE samples exhibited minima at pH from 6 to 7 and increased with both lower and higher pH values, contrasting the consistent increase in PE with pH shown by SRHSs. No consistent effect of salinity on PE was observed for both SRHSs and YRE samples. Photobleaching increased the spectral slope coefficient between 275 nm and 295 nm in summer, consistent with the behavior of SRHSs, but decreased it in winter, implying a difference in the molecular composition of chromophores between the two seasons. Temperature, salinity, and pH modified the photoalteration of the spectral shape but their effects varied spatially and seasonally. This study demonstrates that CDOM quality, temperature, and pH should be incorporated into models involving quantification of photobleaching.

Functional diversity of benthic ciliate communities in response to environmental gradients in a wetland of Yangtze Estuary, China.

PubMed

Xu, Yuan; Fan, Xinpeng; Warren, Alan; Zhang, Liquan; Xu, Henglong

2018-02-01

Researches on the functional diversity of benthic ecosystems have mainly focused on macrofauna, and studies on functional structure of ciliate communities have been based only on trophic- or size-groups. Current research was carried out on the changing patterns of classical and functional diversity of benthic ciliates in response to environmental gradients at three sites in a wetland in Yangtze Estuary. The results showed that changes of environmental factors (e.g. salinity, sediment grain size and hydrodynamic conditions) in the Yangtze Estuary induce variability in species composition and functional trait distribution. Furthermore, increased species richness and diversity did not lead to significant changes in functional diversity due to functional redundancy. However, salt water intrusion of Yangtze Estuary during the dry season could cause reduced functional diversity of ciliate communities. Current study provides the first insight into the functional diversity of ciliate communities in response to environmental gradients. Copyright © 2018 Elsevier Ltd. All rights reserved.

A magnetic record of heavy metal pollution in the Yangtze River subaqueous delta.

PubMed

Dong, Chenyin; Zhang, Weiguo; Ma, Honglei; Feng, Huan; Lu, Honghua; Dong, Yan; Yu, Lizhong

2014-04-01

The rapid industrial development in the Yangtze River watershed over the last several decades has drawn great attention with respect to heavy metal pollution to the Yangtze River estuary and nearby coastal areas. In this study, a 236 cm long sediment core was retrieved from the Yangtze River subaqueous delta (122°36' E, 31°00' N) in 2008 and analyzed for magnetic properties and geochemical compositions to investigate heavy metal pollution history. The activity of (137)Cs peaked at depth 140 cm, with a broad plateau between 120 cm and 140 cm, suggesting an average sedimentation rate of 3.11 cm yr(-1) for the upper 140 cm layer. Magnetic susceptibility (χ), saturation isothermal remanent magnetization (SIRM), anhysteretic remanent magnetization (χARM) and heavy metal enrichment factors (EF) all showed an upward increase trend above depth 140 cm, suggesting that increased ferrimagnetic mineral concentration was accompanied by heavy metal enrichment in the sediment. Geochemical and granolumetric analyses showed that sediment sources and particle sizes played minor roles in the variations of magnetic properties. The effect of diagenesis, which can lead to the selective removal of magnetic minerals, was noticeable in the lower part of the core (140-236 cm). Co-variation between magnetic properties (χ, SIRM and χARM) and EF of Cu and Pb suggests that the elevated ferrimagnetic mineral concentration can be used as an indicator of heavy metal pollution in the reconstruction of environmental changes in estuarine and coastal settings. Copyright © 2014. Published by Elsevier B.V.

[Preliminary assessment of habitat of juvenile Collichthys lucidus in the Yangtze estuary].

PubMed

Yang, Gang; Zhang, Tao; Zhuang, Ping; Hou, Jun-Li; Wang, Yu; Song, Chao; Zhang, Long-Zhen

2014-08-01

To evaluate the choice preference of fish habitat in the Yangtze estuary, juvenile Collichthys lucidus which is the dominant species in spring was selected. The 4 indicator factors, including abundance of Pseudograpsus albus, salinity, substrate type and water depth, were selected from 19 environmental factors. Then, the indices of the habitat suitability curves of the 4 indicator factors were established, and the HSI of juvenile C. lucidus at each site was calculated. The results indicated that HSI was almost more than 0.5 in North Branch, and less than 0.2 in South Branch. It showed that the North Branch of Yangtze estuary was the main nursery area of C. lucidus. The most suitable growth sector was the area with salinity more than 14, mean grain size of substrate less than 29 μm and water depth 2 to 5 m, which was consistent with the distribution of HSI. The study demonstrated that biological factors could be characterized by the response of juvenile C. lucidus to the environment. Chemical oxygen demand, ammonium nitrogen, total phosphorus and volatile phenol did not have significant correlation with the fish abundance, with which nitrite nitrogen, nitrate nitrogen and total nitrogen had significant positive correlation. It suggested that the eutrophication of the survey area had not damaged the habitat of C. lucidus. However, copper ion and cadmium ion had significant negative correlation with the fish abundance, which indicated that the heavy metal pollution had harmed the growth and distribution of juvenile C. lucidus. It was inferred that the heavy metal pollution was the restrictive factor influencing the fish habitat in Yangtze estuary.

Pre-Miocene birth of the Yangtze River

PubMed Central

Zheng, Hongbo; Clift, Peter D.; Wang, Ping; Tada, Ryuji; Jia, Juntao; He, Mengying; Jourdan, Fred

2013-01-01

The development of fluvial systems in East Asia is closely linked to the evolving topography following India–Eurasia collision. Despite this, the age of the Yangtze River system has been strongly debated, with estimates ranging from 40 to 45 Ma, to a more recent initiation around 2 Ma. Here, we present 40Ar/39Ar ages from basalts interbedded with fluvial sediments from the lower reaches of the Yangtze together with detrital zircon U–Pb ages from sand grains within these sediments. We show that a river containing sediments indistinguishable from the modern river was established before ∼23 Ma. We argue that the connection through the Three Gorges must postdate 36.5 Ma because of evaporite and lacustrine sedimentation in the Jianghan Basin before that time. We propose that the present Yangtze River system formed in response to regional extension throughout eastern China, synchronous with the start of strike–slip tectonism and surface uplift in eastern Tibet and fed by strengthened rains caused by the newly intensified summer monsoon. PMID:23610418

Future Earth Coasts: The Mississippi and Yangtze Rivers as Examples

NASA Astrophysics Data System (ADS)

D'Elia, C.; Xu, K.; Chen, Z.; Day, J.; Le Tissier, M.

2016-02-01

Deltas and estuaries are productive and fertile links between the land and the sea. Deltas occupy only about 5% of the Earth's surface but sustain over a half billion people all around the world. Many river deltas are endangered because of extensive dam and levee construction, declining sediment supply, groundwater withdrawal, relative sea level rise and severe coastal erosion, leading to a variety of threats to natural, economic and social systems. About 630 million people now live at an elevation of 10 m or less above mean sea level, and maintaining sustainable land with a rising sea will be a challenging problem for many major deltaic coasts and cities in the next century. Stemming from 20 years of LOICZ (Land-Ocean Interactions in the Coastal Zone), Future Earth Coasts is a new global initiative that seeks to enable the scientific and social scientific communities to build knowledge through collaborative processes to better understand and address the profound and urgent changes occurring in vulnerable coastal zones. The topics of this comparative study are the Mississippi and Yangtze (Changjiang) Rivers, the largest in the United States and China, respectively. We use these two rivers as examples to evaluate current conditions and catalyze future discussion. The Mississippi and Yangtze both have had long-term observations of physical and biological processes that affect human activities, making it possible to quantify both natural and anthropogenic impacts. We also consider the limits to concept of sustainability for the Earth's biosphere and human civilization, and emphasize biophysical constraints and demographic challenges.

Trace metals in estuaries in the Russian Far East and China: case studies from the Amur River and the Changjiang.

PubMed

Shulkin, Vladimir; Zhang, Jing

2014-11-15

This paper compares the distributions of dissolved and particulate forms of Mn, Fe, Ni, Cu, Zn, Cd, and Pb in the estuaries of the largest rivers in East Asia: the Amur River and the Changjiang (Yangtze River). High suspended solid concentrations, elevated pH, and relatively low dissolved trace metal concentrations are characteristics of the Changjiang. Elevated dissolved Fe and Mn concentrations, neutral pH, and relatively low suspended solid concentrations are characteristics of the Amur River. The transfer of dissolved Fe to suspended forms is typical in the Amur River estuary, though Cd and Mn tend to mobilize to solution, and Cu and Ni are diluted in the estuarine system. Metal concentrations in suspended matter in the Amur River estuary are controlled by the ratio of terrigenous riverine material, enriched in Al and Fe, and marine biogenic particles, enriched in Cu, Mn, Cd, and in some cases Ni. The increase in dissolved forms of Mn, Fe, Ni, Cu, Cd, and Pb compared with river end-member is unique to the Changjiang estuary. Particle-solution interactions are not reflected in bulk suspended-solid metal concentrations in the Changjiang estuary due to the dominance of particulate forms of these metals. Cd is an exception in the Changjiang estuary, where the increase in dissolved Cd is of comparable magnitude to the decrease in particulate Cd. Despite runoff in the Amur River being lower than that in the Changjiang, the fluxes of dissolved Mn, Zn and Fe in the Amur River exceed those in the Changjiang. Dissolved Ni, and Cd fluxes are near equal in both estuaries, but dissolved Cu is lower in the Amur River estuary. The hydrological and physico-chemical river characteristics are dominated at the assessment of river influence on the adjoining coastal sea areas despite differences in estuarine processes. Copyright © 2014 Elsevier B.V. All rights reserved.

Suspended Microplastics in the Surface Water of the Yangtze Estuary System, China: First Observations on Occurrence, Distribution

NASA Astrophysics Data System (ADS)

Zhao, S.

2014-12-01

Levels of microplastics (MPs) in China are completely unknown. Here suspended MPs were characterized quantitatively and qualitatively for the Yangtze Estuary and East China Sea. MPs were extracted via a floatation method. MPs were then counted and categorized according to shape and size under a dissecting microscope. The MP densities were 4137.3±2461.5 and 0.167±0.138 n/m3 in the estuarine and the sea waters, respectively. Plastic abundances varied strongly in the estuary. Higher density in the C transect corroborated that rivers were the important sources of MP to the marine environment. MPs (0.5-5mm) constituted more than 90% of total plastics. Plastic particles (> 5 mm) were observed with a maximum size of 12.46 mm. The most frequent plastics were fibres, followed by granules and films. Plastic spherules occurred sparsely. Transparent and coloured plastics comprised the majority of the particle colours. This study provides clues in understanding MPs fate and potential source.

Insights into the interaction between carbamazepine and natural dissolved organic matter in the Yangtze Estuary using fluorescence excitation-emission matrix spectra coupled with parallel factor analysis.

PubMed

Wang, Ying; Zhang, Manman; Fu, Jun; Li, Tingting; Wang, Jinggang; Fu, Yingyu

2016-10-01

The interaction between carbamazepine (CBZ) and dissolved organic matter (DOM) from three zones (the nearshore, the river channel, and the coastal areas) in the Yangtze Estuary was investigated using fluorescence quenching titration combined with excitation emission matrix spectra and parallel factor analysis (PARAFAC). The complexation between CBZ and DOM was demonstrated by the increase in hydrogen bonding and the disappearance of the C=O stretch obtained from the Fourier transform infrared spectroscopy analysis. The results indicated that two protein-like substances (component 2 and component3) and two humic-like substances (component 1 and 4) were identified in the DOM from the Yangtze Estuary. The fluorescence quenching curves of each component with the addition of CBZ and the Ryan and Weber model calculation results both demonstrated that the different components exhibited different complexation activities with CBZ. The protein-like components had a stronger affinity with CBZ than did the humic-like substances. On the other hand, the autochthonous tyrosine-like C2 played an important role in the complexation with DOM from the river channel and coastal areas, while C3 influenced by anthropogenic activities showed an obvious effect in the nearshore area. DOMs from the river channel have the highest binding capacity for CBZ, which may ascribe to the relatively high phenol content group in the DOM.

The mosaic accessory gene structures of the SXT/R391-like integrative and conjugative elements derived from Vibrio spp. isolated from aquatic products and environment in the Yangtze River estuary, China

PubMed Central

2013-01-01

Background The emergence, resurgence and spread of human food-borne pathogenic Vibrios are one of the major contributors to disease burden and mortality particularly in developing countries with disputable sanitary conditions. Previous research on pathogenic Vibrio cholerae and Vibrio parahaemolitycus derived from clinical samples has proposed links between acquisition of virulence and multiple drug resistance traits and intercellular transmissibility of mobile genetic elements in the environment. To date, very few information is available on environmental Vibrio isolates. In this study, we characterized eleven Vibrio strains bearing the SXT/R391-like integrative and conjugative elements (ICEs) derived from aquatic products and environment in the Yangtze River Estuary, China. Results The eleven Vibrio strains were isolated in 2010 to 2011, and taxonomically identified, which included six Vibrio cholerae, three Vibrio parahaemolyticus, one Vibrio alginolyticus and one Vibrio natriegens. Most of the strains displayed strong resistance phenotypes to ampicillin, mercury and chromium. The majority of their ICEs, which belong to S and R exclusion system groups, contain ICEs-chromosome junction sequences and highly conserved core-genes required for ICE transfer. However, comparative sequence analysis uncovered interesting diversity in their mosaic accessory gene structures, which carry many novel genes that have not been described in any known ICEs to date. In addition, antibiotic resistance was transmitted by ICEVchChn6 and ICEVpaChn1 from V. cholerae, V. parahaemolyticus to E. coli MG1655 via conjugation, respectively. Our data also revealed that the ICEs characterized in this study are phylogenetically distant from most of the SXT/R391 ICEs reported previously, which may represent a novel cluster likely shaped by the ecological environment in the Yangtze River Estuary, China. Conclusions This study constitutes the first investigation of ICEs-positive Vibrio spp. in the

Tide-Dominated Tract (TDT) as a key sedimentary zone characterizing tide-dominated large-river delta and estuary systems

NASA Astrophysics Data System (ADS)

Saito, Y.

2017-12-01

Large rivers in continents have a characteristic of slow rise and fall in water levels during floods or the wet season due to a wide drainage basin. A gentle river gradient and large water discharge have relatively large tidal ranges at the river mouth, resulting in large backwater effects further upstream. The result of the Mekong River survey (386 riverbed sediments, river topography, CTD, and biofacies) shows that the distributary channels of the Mekong River delta in Vietnam are divided into two parts: the landward river-dominated tract (RDT) and seaward tide-dominated tract (TDT). The RDT is characterized by a highly variable and deepening trend in water depth and coarse-grained sediments with a fining trend downstream. The TDT is characterized by a shallowing trend in water depth with river-widening, smooth riverbeds, a straight shape, and heterolithic f- to vf-sand and mud alternation (tidal thythmite). The boundary of both tracts is sharply identified by sediment facies and river morphology. Sediment facies indicates that the dominant sedimentary process of bottom sediments is "bedload" in the RDT and "suspension" in the TDT. Daily tidal changes are observed through the year, while water-level changes during the flood/wet season are limited in the TDT. Saltwater intrusion is limited within the seaward part of the TDT alone ( 50 km), close to final bifurcation points. However, brackish-water biofacies is observed in the TDT mainly due to diluted brackish water and/or tolerance to the freshwater environment. These characteristics are also found in the Yangtze; the distance of the TDT/RDT boundary from the river mouth is ca. 100 km in the Mekong, and 200 km in the Yangtze. The preservation potential of sediments in a TDT is low in a progradational system, and high in abandoned channels. The early Holocene transgressive estuary system in the incised valley of the Yangtze formed during the Last Glacial Maximum was composed of 20 m-thick fine-grained heterolithic

Diversity, abundance, and possible sources of fecal bacteria in the Yangtze River.

PubMed

Sun, Haohao; He, Xiwei; Ye, Lin; Zhang, Xu-Xiang; Wu, Bing; Ren, Hongqiang

2017-03-01

The fecal bacteria in natural waters may pose serious risks on human health. Although many source tracking methods have been developed and used to determine the possible sources of the fecal pollution, little is known about the overall diversity and abundance of fecal bacterial community in natural waters. In this study, a method based on fecal bacterial sequence library was introduced to evaluate the fecal bacterial profile in the Yangtze River (Nanjing section). Our results suggested that the Yangtze River water harbors diverse fecal bacteria. Fifty-eight fecal operational taxonomic units (97% identity level) were detected in the Yangtze River water samples and the relative abundance of fecal bacteria in these samples ranged from 0.1 to 8%. It was also found that the relative abundances of the fecal bacteria in locations near to the downstream of wastewater treatment plants were obviously higher than those in other locations. However, the high abundance of fecal bacteria could decrease to the normal level in 2~4 km in the river due to degradation or dilution, and the overall fecal bacteria level changed little when the Yangtze River flew through the Nanjing City. Moreover, the fecal bacteria in the Yangtze River water were found to be highly associated (Spearman rho = 0.804, P < 0.001) with the potential pathogenic bacteria. Collectively, the findings in this study reveal the diversity, abundance, and possible sources of fecal bacteria in the Yangtze River and advance our understandings of the fecal bacteria community in the natural waters.

Trematode Aspidogastrea found in the freshwater mussels in the Yangtze River basin.

PubMed

Zhan, Xiaodong; Li, Chaopin; Wu, Hua

2017-03-30

To investigate the prevalence of trematode Aspidogastrea in the freshwater mussels in the Yangtze River basin within Anhui province, China. We initially harvested the freshwater mussels living in the Yangtze River running through Anhui area, and labeled them with corresponding number. Then the samples were dissected for isolating the flukes, which were identified by conventional staining. Infection rate of trematode Aspidogastrea in freshwater mussels in the Yangtze River basin within the territory of Anhui province was 30.38% (103/339) in general, and a total of 912 flukes of Aspidogastrea were detected in the 103 mussels, with average infection rate of 8.85 for each mussel. Trematode Aspidogastrea is prevalent in the freshwater bivalves living in the Yangtze River basin running through Anhui area, and the treamatode was identified as Aspidogaster sp. belong to Aspidogaste under Aspidogastridae of Aspidogastrea.

Experimental investigation on water quality standard of Yangtze River water source heat pump.

PubMed

Qin, Zenghu; Tong, Mingwei; Kun, Lin

2012-01-01

Due to the surface water in the upper reaches of Yangtze River in China containing large amounts of silt and algae, high content of microorganisms and suspended solids, the water in Yangtze River cannot be used for cooling a heat pump directly. In this paper, the possibility of using Yangtze River, which goes through Chongqing, a city in southwest China, as a heat source-sink was investigated. Water temperature and quality of the Yangtze River in the Chongqing area were analyzed and the performance of water source heat pump units in different sediment concentrations, turbidity and algae material conditions were tested experimentally, and the water quality standards, in particular surface water conditions, in the Yangtze River region that adapt to energy-efficient heat pumps were also proposed. The experimental results show that the coefficient of performance heat pump falls by 3.73% to the greatest extent, and the fouling resistance of cooling water in the heat exchanger increases up to 25.6% in different water conditions. When the sediment concentration and the turbidity in the river water are no more than 100 g/m3 and 50 NTU respectively, the performance of the heat pump is better, which can be used as a suitable river water quality standard for river water source heat pumps.

Import and export fluxes of macrozooplankton are taxa- and season-dependent at Jiuduansha marsh, Yangtze River estuary

NASA Astrophysics Data System (ADS)

Qin, Haiming; Sheng, Qiang; Chu, Tianjiang; Wang, Sikai; Wu, Jihua

2015-09-01

Macrozooplankton may play important roles in influencing nutrient exchange between salt marsh and nearby estuarine ecosystems through predator-prey interactions and their transport by tidal flows. In this study, macrozooplankton transport through year-round monthly sampling was investigated in a salt marsh creek of the Yangtze River estuary. Twenty-one orders of macrozooplankton were captured. Calanoida and Decapoda were dominant and numerically comprised 59.59% and 37.59% respectively of the total captured macrozooplankton throughout the year. Decapoda mainly occurred in April, May and June. In other months, the Calanoida contributed over 90% of the total individuals. The annual Ferrari index (I) for total individual number of macrozooplankton was 0.27, which generally supports the viewpoint that salt marshes are sources of zooplankton. The salt marsh was mainly a source for decapods and mysids, possibly because of larval release in their breeding seasons. The marsh was also a source for amphipods, probably because some benthic forms became transient planktonic forms during tidal water flushing. Copepods and fish larvae exhibited net import into the salt marsh, which may result from predation from salt marsh settlers or retention in the salt marsh. Monthly Ferrari index (I) estimations revealed that the role of the salt marsh as a sink or source of macrozooplankton was time-dependent, which is related to the life history of animals. This study showed that whether the salt marsh zooplankton act as energy importers or exporters is group/taxa-dependent and time-dependent.

[Vulnerability assessment on the coastal wetlands in the Yangtze Estuary under sea-level rise].

PubMed

Cui, Li-Fang; Wang, Ning; Ge, Zhen-Ming; Zhang, Li-Quan

2014-02-01

To study the response of coastal wetlands to climate change, assess the impacts of climate change on the coastal wetlands and formulate feasible and practical mitigation strategies are the important prerequisite for securing coastal ecosystems. In this paper, the possible impacts of sea level rise caused by climate change on the coastal wetlands in the Yangtze Estuary were analyzed by the Source-Pathway-Receptor-Consequence (SPRC) model and IPCC definition on the vulnerability. An indicator system for vulnerability assessment was established, in which sea-level rise rate, subsidence rate, habitat elevation, inundation threshold of habitat and sedimentation rate were selected as the key indicators. A quantitatively spatial assessment method based on the GIS platform was established by quantifying each indicator, calculating the vulnerability index and grading the vulnerability index for the assessment of coastal wetlands in the Yangtze Estuary under the scenarios of sea-level rise. The vulnerability assessments on the coastal wetlands in the Yangtze Estuary in 2030 and 2050 were performed under two sea-level rise scenarios (the present sea-level rise trend over recent 30 years and IPCC A1F1 scenario). The results showed that with the projection in 2030 under the present trend of sea-level rise (0.26 cm x a(-1)), 6.6% and 0.1% of the coastal wetlands were in the low and moderate vulnerabilities, respectively; and in 2050, 9.8% and 0.2% of the coastal wetlands were in low and moderate vulnerabilities, respectively. With the projection in 2030 under the A1F1 scenario (0.59 cm x a(-1)), 9.0% and 0.1% of the coastal wetlands were in the low and moderate vulnerabilities, respectively; and in 2050, 9.5%, 1.0% and 0.3% of the coastal wetlands were in the low, moderate and high vulnerabilities, respectively.

Wastewater discharge impact on drinking water sources along the Yangtze River (China).

PubMed

Wang, Zhuomin; Shao, Dongguo; Westerhoff, Paul

2017-12-01

Unplanned indirect (de facto) wastewater reuse occurs when wastewater is discharged into surface waters upstream of potable drinking water treatment plant intakes. This paper aims to predict percentages and trends of de facto reuse throughout the Yangtze River watershed in order to understand the relative contribution of wastewater discharges into the river and its tributaries towards averting water scarcity concerns. The Yangtze River is the third longest in the world and supports more than 1/15 of the world's population, yet the importance of wastewater on the river remains ill-defined. Municipal wastewater produced in the Yangtze River Basin increased by 41% between 1998 and 2014, from 2580m 3 /s to 3646m 3 /s. Under low flow conditions in the Yangtze River near Shanghai, treated wastewater contributions to river flows increased from 8% in 1998 to 14% in 2014. The highest levels of de facto reuse appeared along a major tributary (Han River) of the Yangtze River, where de facto reuse can exceed 20%. While this initial analysis of de facto reuse used water supply and wastewater data from 110 cities in the basin and 11 gauging stations with >50years of historic streamflow data, the outcome was limited by the lack of gauging stations at more locations (i.e., data had to be predicted using digital elevation mapping) and lack of precise geospatial location of drinking water intakes or wastewater discharges. This limited the predictive capability of the model relative to larger datasets available in other countries (e.g., USA). This assessment is the first analysis of de facto wastewater reuse in the Yangtze River Basin. It will help identify sections of the river at higher risk for wastewater-related pollutants due to presence of-and reliance on-wastewater discharge that could be the focus of field studies and model predictions of higher spatial and temporal resolution. Copyright © 2017 Elsevier B.V. All rights reserved.

[Distribution and changes in species composition and abundance of ichthyoplankton in the Yangtze estuary].

PubMed

Zhang, Heng; Yang, Sheng-Long; Meng, Hai-Xing

2012-06-01

Based on four surveys of eggs and larvae in the Yangtze estuary in 2005 (April and November) and 2006 (April and September), combined with the historical data of the wetland in 1990 (September) and 1991 (March), we analyzed seasonal changes in fish species composition and quantity of ichthyoplankton. Thirty-six species of egg and larvae were collected and marine fish species were the highest represented ecological guild. Average fish species and average abundance in spring were lower than in autumn for every survey. The total number of eggs in brackish water was higher than in fresh water, but the total number of larvae and juveniles in brackish water was lower. The abundance of eggs and larvae during from 2005 to 2006 in both spring and autumn was higher compared to those from 1990 to 1991. Obvious differences in species composition in September between 1990 and 2006 were found, especially for Erythroculter ilishaeformis and Neosalanx taihuensis. Fish species composition and quantity within the ichthyoplankton community has obviously changed in the Yangtze estuary over the last 20 years.

[Surveillance and forecast for schistosome infectivity of Yangtze River and Hanbeihe River during flooding in Hubei Province].

PubMed

Tu, Zu-Wu; Cai, Shun-Xiang; Huang, Xi-Bao; Su, Zheng-Ming; Gao, Hua; Chen, Yan-Yan; Cao, Mu-Min; Mao, Guan-Xiang; Xia, Ping-Feng

2012-04-01

To investigate the schistosome infectivity of the water body of the Yangtze River and Hanbeihe River during flooding in Hubei Province. The Oncomelania snail status was investigated in 17 sites of the Yangtze River and Hanbei River, and the infectivity of schistosome in sentinel mice was also determined. In the Yangtze River and Hanbei River, the average densities of living snails were 0.35 snails/0.1 m2 and 0.67 snails/0.1 m2 respectively, and the average infection rates of snails were 0.33% and 0.05%, respectively. The sentinel mouse surveillances were carried out twice in 10 sites of the Yangtze River. During the first surveillance the infection rate was 5.5% with 4 positive environment sites, and that was 5.5% with 7 positive environment sites in the second surveillance. The sentinel mouse surveillance was carried out once in 7 sites of the Hanbeihe River, and the infection rate was 11.9% with 4 positive environment sites. By monitoring schistosome infection of the water body, we can understand the threat of environment and provide warning information to prevent from the outbreak and spread of acute schistosomiasis. We can also indirectly get many messages about the quality of snail investigation and the effect of mollusciciding.

[Oncomelania hupensis snail distribution in working areas of Yangtze River hydrologic agencies located in middle and lower reaches of Yangtze River in 2016].

PubMed

Min, Xu; Suo-Xin, Huang; Zheng-Yuan, Zhao; Ben-Jiao, Hu; Jun, Fu; Si-Min, Dai; Li-Hong, Wen

2016-10-13

To understand the Oncomelania hupensis snail distribution in the working areas of Yangtze River hydrologic agencies located in the middle and lower reaches of the Yangtze River in 2016, so as to provide the evidence for assessing the risk of schistosome infection of hydrological workers and establishing the control strategies. The suspicious environments with O. hupensis snails in the above working areas were selected as study areas, and the snail situation was surveyed by the system sampling method combined with the environmental sampling method. The survey data were collected and analyzed statistically. Totally 19 working areas from 17 hydrological agencies were selected as the investigation sites, among which, 10 working areas from 9 agencies were found with O. hupensis snail distribution. The constituent ratio of the areas with snails reached to 38.81% of the investigation areas, the occurrence rate of frames with snails was 3.08%, and the average density of living snails was 0.07 /0.1 m 2 . By comparison, the average density of living snails and occurrence rate of frames with snails in hydrological agencies under the jurisdiction of the Middle Reaches Administrative Bureau were the most serious among three administrative bureaus of the Yangtze River Water Resources Commission. There are various degrees of O. hupensis breeding in the working areas of hydrological agencies located in the middle and lower reaches of the Yangtze River, and the hydrological workers are facing with the risk of schistosome infection.

Assessment of bridge scour in the lower, middle, and upper Yangtze River estuary with riverbed sonar profiling techniques.

PubMed

Zheng, Shuwei; Xu, Y Jun; Cheng, Heqin; Wang, Bo; Lu, Xuejun

2017-12-12

Riverbed scour of bridge piers can cause rapid loss in foundation strength, leading to sudden bridge collapse. This study used multi-beam echo sounders (Seabat 7125) to map riverbed surrounding the foundations of four major bridges in the lower, middle, and upper reaches of the 700-km Yangtze River Estuary (YRE) during June 2015 and September 2016. The high-resolution data were utilized to analyze the morphology of the bridge scour and the deformation of the wide-area riverbed (i.e., 5-18 km long and 1.3-8.3 km wide). In addition, previous bathymetric measurements collected in 1998, 2009, and 2013 were used to determine riverbed erosion and deposition at the bridge reaches. Our study shows that the scour depth surrounding the bridge foundations progressed up to 4.4-19.0 m in the YRE. Over the past 5-15 years, the total channel erosion in some river reaches was up to 15-17 m, possessing a threat to the bridge safety in the YRE. Tide cycles seemed to have resulted in significant variation in the scour morphology in the lower and middle YRE. In the lower YRE, the riverbed morphology displayed one long erosional ditch on both sides of the bridge foundations and a long-strip siltation area distributed upstream and downstream of the bridge foundations; in the middle YRE, the riverbed morphology only showed erosional morphology surrounding the bridge foundations. Large dunes caused deep cuts and steeper contours in the bridge scour. Furthermore, this study demonstrates that the high-resolution grid model formed by point cloud data of multi-beam echo sounders can clearly display the morphology of the bridge scour in terms of wide areas and that the sonar technique is a very useful tool in the assessment of bridge scours.

Suspended sediment diffusion mechanisms in the Yangtze Estuary influenced by wind fields

NASA Astrophysics Data System (ADS)

Wang, Lihua; Zhou, Yunxuan; Shen, Fang

2018-01-01

The complexity of suspended sediment concentration (SSC) distribution and diffusion has been widely recognized because it is influenced by sediment supply and various hydrodynamic forcing conditions that vary over space and over time. Sediment suspended by waves and transported by currents are the dominant sediment transport mechanisms in estuarine and coastal areas. However, it is unclear to what extent the SSC distribution is impacted by each hydrodynamic factor. Research on the quantitative influence of wind fields on the SSC diffusion range will contribute to a better understanding of the characteristics of sediment transport change and sedimentary geomorphic evolution. This study determined SSC from three Envisat Medium-Resolution Imaging Spectrometer acquisitions, covering the Yangtze Estuary and adjacent water area under the same season and tidal conditions but with varying wind conditions. SSC was examined based on the Semi-Empirical Radiative Transfer model, which has been well validated with the observation data. Integrating the corresponding wind field information from European Centre for Medium-Range Weather Forecasts further facilitated the discussion of wind fields affecting SSC, and in turn the influence of water and suspended sediment transportation and diffusion in the Yangtze estuarine and coastal area. The results demonstrated that the SSC present much more distinctive fluvial features in the inner estuary and wind fields are one of the major factors controlling the range of turbid water diffusion.

Characterizing seston in the Penobscot River Estuary.

PubMed

Meseck, Shannon L; Li, Yaqin; Sunila, Inke; Dixon, Mark; Clark, Paul; Lipsky, Christine; Stevens, Justin R; Music, Paul; Wikfors, Gary H

2017-10-01

The Penobscot River Estuary is an important system for diadromous fish in the Northeast United States of American (USA), in part because it is home to the largest remnant population of Atlantic salmon, Salmo salar, in the country. Little is known about the chemical and biological characteristics of seston in the Penobscot River Estuary. This study used estuarine transects to characterize the seston during the spring when river discharge is high and diadromous fish migration peaks in the Penobscot River Estuary. To characterize the seston, samples were taken in spring 2015 for phytoplankton identification, total suspended matter (TSM), percent organic TSM, chlorophyll a, particle size (2 μm-180 μm), particulate carbon and nitrogen concentrations, and stable carbon and nitrogen isotopes. The estuarine profiles indicate that TSM behaved non-conservatively with a net gain in the estuary. As phytoplankton constituted only 1/1000 of the particles, the non-conservative behavior of TSM observed in the estuary was most likely not attributable to phytoplankton. Particulate carbon and nitrogen ratios and stable isotope signals indicate a strong terrestrial, allochthonous signal. The seston in the Penobscot River Estuary was dominated by non-detrital particles. During a short, two-week time period, Heterosigma akashiwo, a phytoplankton species toxic to finfish, also was detected in the estuary. A limited number of fish samples, taken after the 2015 Penobscot River Estuary bloom of H. akashiwo, indicated frequent pathological gill damage. The composition of seston, along with ichthyotoxic algae, suggest the need for further research into possible effects upon resident and migratory fish in the Penobscot River Estuary. Published by Elsevier Ltd.

Organic micropollutants in the Yangtze River: seasonal occurrence and annual loads.

PubMed

Qi, Weixiao; Müller, Beat; Pernet-Coudrier, Benoit; Singer, Heinz; Liu, Huijuan; Qu, Jiuhui; Berg, Michael

2014-02-15

Twenty percent of the water run-off from China's land surface drains into the Yangtze River and carries the sewage of approximately 400 million people out to sea. The lower stretch of the Yangtze therefore offers the opportunity to assess the pollutant discharge of a huge population. To establish a comprehensive assessment of micropollutants, river water samples were collected monthly from May 2009 to June 2010 along a cross-section at the lowermost hydrological station of the Yangtze River not influenced by the tide (Datong Station, Anhui province). Following a prescreening of 268 target compounds, we examined the occurrence, seasonal variation, and annual loads of 117 organic micropollutants, including 51 pesticides, 43 pharmaceuticals, 7 household and industrial chemicals, and 16 polycyclic aromatic hydrocarbons (PAHs). During the 14-month study, the maximum concentrations of particulate PAHs (1-5 μg/g), pesticides (11-284 ng/L), pharmaceuticals (5-224 ng/L), and household and industrial chemicals (4-430 ng/L) were generally lower than in other Chinese rivers due to the dilution caused of the Yangtze River's average water discharge of approximately 30,000 m(3)/s. The loads of most pesticides, anti-infectives, and PAHs were higher in the wet season compared to the dry season, which was attributed to the increased agricultural application of chemicals in the summer, an elevated water discharge through the sewer systems and wastewater treatment plants (WWTP) as a result of high hydraulic loads and the related lower treatment efficiency, and seasonally increased deposition from the atmosphere and runoff from the catchment. The estimated annual load of PAHs in the river accounted for some 4% of the total emission of PAHs in the whole Yangtze Basin. Furthermore, by using sucralose as a tracer for domestic wastewater, we estimate a daily disposal of approximately 47 million m(3) of sewage into the river, corresponding to 1.8% of its average hydraulic load. In summary

Assessment of pollutant mean concentrations in the Yangtze estuary based on MSN theory.

PubMed

Ren, Jing; Gao, Bing-Bo; Fan, Hai-Mei; Zhang, Zhi-Hong; Zhang, Yao; Wang, Jin-Feng

2016-12-15

Reliable assessment of water quality is a critical issue for estuaries. Nutrient concentrations show significant spatial distinctions between areas under the influence of fresh-sea water interaction and anthropogenic effects. For this situation, given the limitations of general mean estimation approaches, a new method for surfaces with non-homogeneity (MSN) was applied to obtain optimized linear unbiased estimations of the mean nutrient concentrations in the study area in the Yangtze estuary from 2011 to 2013. Other mean estimation methods, including block Kriging (BK), simple random sampling (SS) and stratified sampling (ST) inference, were applied simultaneously for comparison. Their performance was evaluated by estimation error. The results show that MSN had the highest accuracy, while SS had the highest estimation error. ST and BK were intermediate in terms of their performance. Thus, MSN is an appropriate method that can be adopted to reduce the uncertainty of mean pollutant estimation in estuaries. Copyright © 2016 Elsevier Ltd. All rights reserved.

Mid-Holocene hydrology change in the south Taihu area of the Yangtze delta plain, China, and its relationship to the development of Neolithic cultures

NASA Astrophysics Data System (ADS)

Chen, T.; Ryves, D.; Wang, Z.; Lewis, J.

2017-12-01

During the middle Holocene, the hydrological environments in the Taihu Plain, Yangtze Delta, China, varied tremendously under the influence of sea-level and climate change. Simultaneously, several Neolithic cultures, such as, the Majiabang, Songze, and Liangzhu culture, developed in this region. Basing on AMS14C dating, diatom identification, measurements of C-N elements and their stable isotopes of sediments from core DTX4 and DTX10, obtained in the East Tiaoxi Plain, south Taihu plain, we discussed the influence of hydrology changes on the development of Neolithic cultures. The results revealed that the East Tiaoxi River plain was in an estuary (the Palaeo-Taihu Estuary) condition at 7500 cal. yr BP, undergoing elevated in-fill in response to rapid sea-level rise. After 7500 cal. yr BP, low salinity conditions occurred, likely influenced by the Yangtze freshwater evidenced by constant occurrence of Aulacoseira granulata, which implied Yangtze runoff discharged along the channel of Palaeo-incised Taihu valley into the Hangzhou Bay during the middle Holocene. Sea-water penetration interrupted after 7000 cal. yr BP caused by an abrupt sea-level rise. During 6500-5600 cal. yr BP, sea-water retreated gradually, corresponding to the infilling of Palaeo-Taihu Estuary. Combing records from previously studied cores in the Taihu plain, stable freshwater condition (or dry land) established in most area of the Taihu plain after 5600 cal. yr BP due to the closure of the Palaeo-Taihu Estuary. We speculate that the low-salinity marsh started at about 7500-7000 cal. yr BP probably attracted the early Majiabang people to live around the Palaeo-Taihu Estuary. The sea water penetration between 7000-6500 cal. yr BP matches the left of the late Majiabang and the early-middle Songze people lived in the east of the Palaeo-Taihu Estuary, to the north and east of the Taihu Plain. The context of stable freshwater condition (or dry land) in the East Tiaoxi River plain promoted the

Uncertainty in positive matrix factorization solutions for PAHs in surface sediments of the Yangtze River Estuary in different seasons.

PubMed

Liu, Ruimin; Men, Cong; Yu, Wenwen; Xu, Fei; Wang, Qingrui; Shen, Zhenyao

2018-01-01

To examine the variabilities of source contributions in the Yangtze River Estuary (YRE), the uncertainty based on the positive matrix factorization (PMF) was applied to the source apportionment of the 16 priority PAHs in 120 surface sediment samples from four seasons. Based on the signal-to-noise ratios, the PAHs categorized as "Bad" might drop out of the estimation of bootstrap. Next, the spatial variability of residuals was applied to determine which species with non-normal curves should be excluded. The median values from the bootstrapped solutions were chosen as the best estimate of the true factor contributions, and the intervals from 5th to 95th percentile represent the variability in each sample factor contribution. Based on the results, the median factor contributions of wood grass combustion and coke plant emissions were highly correlated with the variability (R 2  = 0.6797-0.9937) in every season. Meanwhile, the factor of coal and gasoline combustion had large variability with lower R 2 values in every season, especially in summer (0.4784) and winter (0.2785). The coefficient of variation (CV) values based on the Bootstrap (BS) simulations were applied to indicate the uncertainties of PAHs in every factor of each season. Acy, NaP and BgP always showed higher CV values, which suggested higher uncertainties in the BS simulations, and the PAH with the lowest concentration among all PAHs usually became the species with higher uncertainties. Copyright © 2017 Elsevier Ltd. All rights reserved.

Mapping Water Vulnerability of the Yangtze River Basin: 1994-2013.

PubMed

Sun, Fengyun; Kuang, Wenhui; Xiang, Weining; Che, Yue

2016-11-01

A holistic understanding of the magnitude and long-term trend of water vulnerability is essential for making management decisions in a given river basin. Existing procedures to assess the spatiotemporal dynamic of water vulnerability in complex mega-scale river basins are inadequate; a new method named ensemble hydrologic assessment was proposed in this study, which allows collection of data and knowledge about many aspects of water resources to be synthesized in a useful way for vulnerability assessment. The objective of this study is to illustrate the practical utility of such an integrated approach in examining water vulnerability in the Yangtze River Basin. Overall, the results demonstrated that the ensemble hydrologic assessment model could largely explain the spatiotemporal evolution of water vulnerability. This paper improves understanding of the status and trends of water resources in the Yangtze River Basin.

[Analysis of trend of Oncomelania snail status in Yangtze River valley of Anhui Province, 1998-2009].

PubMed

He, Jia-Chang; Wang, Jia-Sheng; Lu, Jin-You; Li, Ting-Ting; Gao, Feng-Hu; Zhou, Ping; Zhu, Chuan-Ming; He, Long-Zhu; Yu, Bei-Bei; Zhang, Shi-Qing

2011-04-01

To understand the trend of Oncomelania hupensis snail distribution in Yangtze River valley of Anhui Province so as to provide an evidence for making out schistosomiasis prevention and control strategies in the future. The snail data from 1998 to 2009 of the Yangtze River valley in Anhui Province were collected including the snail area, newly occurred and re-occurred snail areas, densities of snails and infected snails, etc., and the trend and influence factors were analyzed. With several fluctuations, the snail area showed a trend of declining in general after the devastating summer flooding in 1998. From 1998 to 2009, 3 peaks of newly occurred snail areas appeared in 1998, 2004 and 2006 and 2 peaks of reoccurred snail areas appeared in 1998 and 2004. The densities of living snails and infected snails were more severe in banks of the Yangtze River than in islets of the Yangtze River. During 12 years, 1 peak of living snail density appeared in 2003, and 3 peaks of infected snail density appeared in 1999, 2003-2004 and 2006 in the islets of the Yangtze River. The densities of living snails and infected snails in banks of the Yangtze both appeared 1 peak in 1998. The distribution of snails in the Yangtze River valley is related to nature, society and financial circumstances, and it is hard to completely perform the snail control in a short-term. Therefore, at the same time of strengthening snail control, we should also strengthen infectious source control.

Occurrence and distribution of dissolved tellurium in Changjiang River estuary

NASA Astrophysics Data System (ADS)

Wu, Xiaodan; Song, Jinming; Li, Xuegang

2014-03-01

With the implementation of the GEOTRACES program, the biogeochemical cycle and distribution of tellurium (Te) in marine environments are becoming increasing environmental concerns. In this study, the concentration of dissolved Te in the Changjiang (Yangtze) River estuary and nearby waters was determined in May 2009 by hydride-generation atomic fluorescence spectrometry to elucidate the abundance, dominant species, distribution, and relationship with environmental factors. Results show that: (1) dissolved Te was low owing to its low abundance in the Earth's crust, high insolubility in water, and strong affinity to particulate matter; (2) Te(IV) and Te(VI) predominated in surface water. Te(VI) was the dominant species in bottom water, and Te(IV) was the minor species; (3) Horizontally, resulting from low phytoplankton metabolism and the weak reduction from Te(VI) to Te(IV) in the shore, Te(IV) was concentrated in the central zone instead of the coastal region. However, Te(VI) was abundant near the mouth of the Changjiang River where the Changjiang water is diluted and in the area to the south where the Taiwan Warm Current invaded. In the adsorption-desorption process, Te(IV) was negatively related to suspended particulate matter (SPM), indicating that it was adsorbed by particulate matter. While for Te(VI), the positive correlation with SPM suggested that it was desorbed from the solid phase. In the estuary, dissolved Te had a negative correlation to salinity. However, it deviated from the dilution line in high-salinity regions due to the invasion of the Taiwan Warm Current and the mineralization of organic matter. The relationship between Te(IV) and SPM nutrients indicated that it was more bioavailable and more related to phosphorus than to nitrogen. Progress in the field is slow and more research is needed to quantify the input of Te to the estuary and evaluate the biochemical role of organisms.

Bacterial community structure in response to environmental impacts in the intertidal sediments along the Yangtze Estuary, China.

PubMed

Guo, Xing-Pan; Lu, Da-Pei; Niu, Zuo-Shun; Feng, Jing-Nan; Chen, Yu-Ru; Tou, Fei-Yun; Liu, Min; Yang, Yi

2018-01-01

This study was designed to investigate the characteristics of bacterial communities in intertidal sediments along the Yangtze Estuary and their responses to environmental factors. The results showed that bacterial abundance was significantly correlated with salinity, SO 4 2- and total organic carbon, while bacterial diversity was significantly correlated with SO 4 2- and total nitrogen. At different taxonomic levels, both the dominant taxa and their abundances varied among the eight samples, with Proteobacteria being the most dominant phylum in general. Cluster analysis revealed that the bacterial community structure was influenced by river runoff and sewerage discharge. Moreover, SO 4 2- , salinity and total phosphorus were the vital environmental factors that influenced the bacterial community structure. Quantitative PCR and sequencing of sulphate-reducing bacteria indicated that the sulphate reduction process occurs frequently in intertidal sediments. These findings are important to understand the microbial ecology and biogeochemical cycles in estuarine environments. Copyright © 2017 Elsevier Ltd. All rights reserved.

Spatial-Temporal Variations of Chlorophyll-a in the Adjacent Sea Area of the Yangtze River Estuary Influenced by Yangtze River Discharge.

PubMed

Wang, Ying; Jiang, Hong; Jin, Jiaxin; Zhang, Xiuying; Lu, Xuehe; Wang, Yueqi

2015-05-20

Carrying abundant nutrition, terrigenous freshwater has a great impact on the spatial and temporal heterogeneity of phytoplankton in coastal waters. The present study analyzed the spatial-temporal variations of Chlorophyll-a (Chl-a) concentration under the influence of discharge from the Yangtze River, based on remotely sensed Chl-a concentrations. The study area was initially zoned to quantitatively investigate the spatial variation patterns of Chl-a. Then, the temporal variation of Chl-a in each zone was simulated by a sinusoidal curve model. The results showed that in the inshore waters, the terrigenous discharge was the predominant driving force determining the pattern of Chl-a, which brings the risk of red tide disasters; while in the open sea areas, Chl-a was mainly affected by meteorological factors. Furthermore, a diversity of spatial and temporal variations of Chl-a existed based on the degree of influences from discharge. The diluted water extended from inshore to the east of Jeju Island. This process affected the Chl-a concentration flowing through the area, and had a potential impact on the marine environment. The Chl-a from September to November showed an obvious response to the discharge from July to September with a lag of 1 to 2 months.

Spatial-Temporal Variations of Chlorophyll-a in the Adjacent Sea Area of the Yangtze River Estuary Influenced by Yangtze River Discharge

PubMed Central

Wang, Ying; Jiang, Hong; Jin, Jiaxin; Zhang, Xiuying; Lu, Xuehe; Wang, Yueqi

2015-01-01

Carrying abundant nutrition, terrigenous freshwater has a great impact on the spatial and temporal heterogeneity of phytoplankton in coastal waters. The present study analyzed the spatial-temporal variations of Chlorophyll-a (Chl-a) concentration under the influence of discharge from the Yangtze River, based on remotely sensed Chl-a concentrations. The study area was initially zoned to quantitatively investigate the spatial variation patterns of Chl-a. Then, the temporal variation of Chl-a in each zone was simulated by a sinusoidal curve model. The results showed that in the inshore waters, the terrigenous discharge was the predominant driving force determining the pattern of Chl-a, which brings the risk of red tide disasters; while in the open sea areas, Chl-a was mainly affected by meteorological factors. Furthermore, a diversity of spatial and temporal variations of Chl-a existed based on the degree of influences from discharge. The diluted water extended from inshore to the east of Jeju Island. This process affected the Chl-a concentration flowing through the area, and had a potential impact on the marine environment. The Chl-a from September to November showed an obvious response to the discharge from July to September with a lag of 1 to 2 months. PMID:26006121

Genetic structure and diversity of Nodularia douglasiae (Bivalvia: Unionida) from the middle and lower Yangtze River drainage.

PubMed

Liu, Xiongjun; Cao, Yanling; Xue, Taotao; Wu, Ruiwen; Zhou, Yu; Zhou, Chunhua; Zanatta, David T; Ouyang, Shan; Wu, Xiaoping

2017-01-01

The Yangtze River drainage in China is among the most species rich rivers for freshwater mussels (order Unionida) on Earth with at least 68 species known. The freshwater mussels of the Yangtze River face a variety of threats with indications that species are declining in abundance and area of occupancy. This study represents the first analyses of the genetic structure and diversity for the common and widespread freshwater mussel Nodularia douglasiae based on microsatellite DNA genotypes and mitochondrial DNA sequences. Phylogenetic analysis a fragment of the COI mitochondrial gene indicated that N. douglasiae collected from across the middle and lower Yangtze River drainage are monophyletic with N. douglasiae from Japan, Russia, and South Korea. The results of the analysis of both the mtDNA and microsatellite datasets indicated that the seven collection locations of N. douglasiae in the middle and lower Yangtze River drainage showed high genetic diversity, significant genetic differentiation and genetic structure, and stable population dynamics over time. Moreover, we found that the connections among tributaries rivers and lakes in the Yangtze River drainage were important in maintaining gene flow among locations that N. douglasiae inhabits. An understanding of the genetic structure and diversity of a widespread species like N. douglasiae could be used as a surrogate to better understand the populations of other freshwater mussel species that are more rare in the Yangtze River drainage. At the same time, these results could provide a basis for the protection of genetic diversity and management of unionid mussels diversity and other aquatic organisms in the system.

Genetic structure and diversity of Nodularia douglasiae (Bivalvia: Unionida) from the middle and lower Yangtze River drainage

PubMed Central

Liu, Xiongjun; Cao, Yanling; Xue, Taotao; Wu, Ruiwen; Zhou, Yu; Zhou, Chunhua; Zanatta, David T.; Ouyang, Shan

2017-01-01

The Yangtze River drainage in China is among the most species rich rivers for freshwater mussels (order Unionida) on Earth with at least 68 species known. The freshwater mussels of the Yangtze River face a variety of threats with indications that species are declining in abundance and area of occupancy. This study represents the first analyses of the genetic structure and diversity for the common and widespread freshwater mussel Nodularia douglasiae based on microsatellite DNA genotypes and mitochondrial DNA sequences. Phylogenetic analysis a fragment of the COI mitochondrial gene indicated that N. douglasiae collected from across the middle and lower Yangtze River drainage are monophyletic with N. douglasiae from Japan, Russia, and South Korea. The results of the analysis of both the mtDNA and microsatellite datasets indicated that the seven collection locations of N. douglasiae in the middle and lower Yangtze River drainage showed high genetic diversity, significant genetic differentiation and genetic structure, and stable population dynamics over time. Moreover, we found that the connections among tributaries rivers and lakes in the Yangtze River drainage were important in maintaining gene flow among locations that N. douglasiae inhabits. An understanding of the genetic structure and diversity of a widespread species like N. douglasiae could be used as a surrogate to better understand the populations of other freshwater mussel species that are more rare in the Yangtze River drainage. At the same time, these results could provide a basis for the protection of genetic diversity and management of unionid mussels diversity and other aquatic organisms in the system. PMID:29261733

Juvenile salmon usage of the Skeena River estuary.

PubMed

Carr-Harris, Charmaine; Gottesfeld, Allen S; Moore, Jonathan W

2015-01-01

Migratory salmon transit estuary habitats on their way out to the ocean but this phase of their life cycle is more poorly understood than other phases. The estuaries of large river systems in particular may support many populations and several species of salmon that originate from throughout the upstream river. The Skeena River of British Columbia, Canada, is a large river system with high salmon population- and species-level diversity. The estuary of the Skeena River is under pressure from industrial development, with two gas liquefaction terminals and a potash loading facility in various stages of environmental review processes, providing motivation for understanding the usage of the estuary by juvenile salmon. We conducted a juvenile salmonid sampling program throughout the Skeena River estuary in 2007 and 2013 to investigate the spatial and temporal distribution of different species and populations of salmon. We captured six species of juvenile anadromous salmonids throughout the estuary in both years, and found that areas proposed for development support some of the highest abundances of some species of salmon. Specifically, the highest abundances of sockeye (both years), Chinook in 2007, and coho salmon in 2013 were captured in areas proposed for development. For example, juvenile sockeye salmon were 2-8 times more abundant in the proposed development areas. Genetic stock assignment demonstrated that the Chinook salmon and most of the sockeye salmon that were captured originated from throughout the Skeena watershed, while some sockeye salmon came from the Nass, Stikine, Southeast Alaska, and coastal systems on the northern and central coasts of British Columbia. These fish support extensive commercial, recreational, and First Nations fisheries throughout the Skeena River and beyond. Our results demonstrate that estuary habitats integrate species and population diversity of salmon, and that if proposed development negatively affects the salmon populations that

Assessment on vulnerability of coastal wetlands to sea level rise in the Yangtze Estuary, China

NASA Astrophysics Data System (ADS)

Cui, L.; Ge, Z.; Zhang, L.

2013-12-01

The Yangtze Delta in China is vital economic hubs in terms of settlement, industry, agriculture, trade and tourism as well as of great environmental significance. In recent decades, the prospect of climate change, in particular sea level rise and its effects on low lying coastal areas have generated worldwide attention to coastal ecosystems. Coastal wetlands, as important parts of coastal ecosystem, are particularly sensitive to sea level rise. To study the responses of coastal wetlands to climate change, assess the impacts of climate change on coastal wetlands and formulate feasible and practical mitigation strategies are the important prerequisites for securing the coastal zone ecosystems. In this study, taking the coastal wetlands in the Yangtze Estuary as a case study, the potential impacts of sea-level rise to coastal wetlands habitat were analyzed by the Source-Pathway-Receptor-Consequence (SPRC) model. The key indicators, such as the sea-level rise rate, subsidence rate, elevation, daily inundation duration of habitat and sedimentation rate, were selected to build a vulnerability assessment system according to the IPCC definition of vulnerability, i.e. the aspects of exposure, sensitivity and adaptation. A quantitatively spatial assessment method on the GIS platform was established by quantifying each indicator, calculating the vulnerability index and grading the vulnerability. The vulnerability assessment on the coastal wetlands in the Yangtze Estuary under the sea level rise rate of the present trend and IPCC A1F1 scenario were performed for three sets of projections of short-term (2030s), mid-term (2050s) and long-term (2100s). The results showed that at the present trend of sea level rise rate of 0.26 cm/a, 92.3 % of the coastal wetlands in the Yangtze Estuary was in the EVI score of 0 in 2030s, i.e. the impact of sea level rise on habitats/species of coastal wetlands was negligible. While 7.4 % and 0.3 % of the coastal wetlands were in the EVI score of

Effects of fish community on occurrences of Yangtze finless porpoise in confluence of the Yangtze and Wanhe Rivers.

PubMed

Zhang, Xiaoke; Yu, Daoping; Wang, Huili; Wan, An; Chen, Minmin; Tao, Feng; Song, Zunrong

2015-06-01

The Yangtze finless porpoise is a subspecies of narrow-ridged finless porpoise endemic to the middle and lower reaches of the Yangtze River and the adjoining Poyang and Dongting Lakes. With the depletion of fish stocks in the Yangtze River in recent decades, food availability has become the most important factor affecting the survival of this subspecies. Despite this, the relationships between fish community and occurrences of porpoise are far from being fully understood. Therefore, during September 2013 to August 2014, the occurrences of porpoise were investigated in confluence of the Yangtze and Wanhe Rivers; fish community was also surveyed synchronously in confluence and two adjacent transects. The results showed that (1) the confluence had maximum fish species richness, and the main dominant species was upper fish, while the other two transects were mainly dominated by demersal fish. ANOVA analyses showed that individual number and yield of upper fish which can be eaten by porpoise (upper edible fish) in the confluence were significantly higher than other two transects. (2) Average group size of the porpoise was 3.7 ± 1.8 individuals. The occurrences of porpoise in different seasons had great differences, and the porpoise was more likely to be detected in autumn and winter. (3) Fish community had significant effects on occurrences of porpoise, and the main influencing factors were fish species richness, individual number, and yield of edible fish, especially the upper edible fish. The results of this study will have important implications for the conservation of porpoise.

Early Development of Four Cyprinids Native to the Yangtze River, China

USGS Publications Warehouse

Chapman, Duane C.

2006-01-01

Chapter 1 -- Notes on the Translation and Use of "A Study of the Early Development of Grass Carp, Black Carp, Silver Carp, and Bighead Carp in the Yangtze River, China" By Duane C. Chapman and Ning Wang Chapter 2 -- A Study of the Early Development of Grass Carp, Black Carp, Silver Carp, and Bighead Carp in the Yangtze River, China By Bolu Yi, Zhishen Liang, Zhitang Yu, Randuan Lin, and Mingjue HeTranslated by Duane C. Chapman and Ning Wang The document A Study of the Early Development of Grass Carp, Black Carp, Silver Carp, and Bighead Carp in the Yangtze River, China (Chapter 2 of this volume) was translated from the Chinese with the approval and assistance of the living authors of that study. It contains the most detailed description available, and approximately 200 drawings, of the early development of the subject fishes. Chapter 1 provides important instructions on the use of the translation, including a description of the Chinese morphometric conventions, which differ from those used by North American scientists. Chapter 1 also provides the historical context in which Chapter 2 was developed, and information on how the larvae of the subject fishes, which have invaded the Mississippi River basin, may be distinguished from other fishes present in the basin.

Application of passive sampling in assessing the occurrence and risk of antibiotics and endocrine disrupting chemicals in the Yangtze Estuary, China.

PubMed

Shi, X; Zhou, J L; Zhao, H; Hou, L; Yang, Y

2014-09-01

Polar organic chemical integrative sampler (POCIS) was used in assessing the occurrence and risk of 12 widely used antibiotics and 5 most potent endocrine disrupting chemicals (EDCs) in the Yangtze Estuary, China. During laboratory validation, the kinetics of pollutant uptake by POCIS were linear, and the sampling rates of most compounds were raised by flow rate and salinity, reaching the highest values at salinity 14‰. The sampling rates varied with the target compounds with the EDCs showing the highest values (overall average=0.123Ld(-1)), followed by chloramphenicols (0.100Ld(-1)), macrolides (0.089Ld(-1)), and finally sulfonamides (0.056Ld(-1)). Validation in the Yangtze Estuary in 2013 showed that the field sampling rates were significantly greater for all compounds except bisphenol A, in comparison to laboratory results, and high-frequency spot sampling is critical for fully validating the passive sampler. The field studies show that antibiotics were widely detected in the Yangtze Estuary, with concentrations varying from below quantification to 1613ngL(-1), suggesting their widespread use and persistence in estuarine waters. The dominating pollutants in July were sulfonamides with a total concentration of 258ngL(-1) and in October were macrolides with a total concentration of 350ngL(-1). The calculation of risk quotient suggested that sulfapyridine, sulfaquinoxaline and erythromycin-H2O may have caused medium damage to sensitive organisms such as fish. Copyright © 2014. Published by Elsevier Ltd.

Distributions of organochlorine compounds in sediments from Jiulong River Estuary and adjacent Western Taiwan Strait: Implications of transport, sources and inventories.

PubMed

Wu, Yuling; Wang, Xinhong; Ya, Miaolei; Li, Yongyu; Hong, Huasheng

2016-12-01

Estuaries and coastal areas strongly influenced by terrestrial inputs resulted from anthropogenic activities. To study the distributions, origins, potential transport and burden of organochlorine compounds (OCs) from river to marginal sea, organochlorine pesticides (OCPs) and polychlorinated biphenyls (PCBs) were investigated in surface sediments collected from a subtropical estuary (Jiulong River Estuary, JRE) and the inner shelf of adjacent Western Taiwan Strait (WTS). The concentrations of OCPs and PCBs were from 5.2 to 551.7 and 1.0-8.1 ng g -1 (dry weight), respectively. OCP concentrations in the JRE were higher than in adjacent WTS, and a decreasing trend with the ascending distance from the estuary to the open sea was observed. Concentrations of DDTs were quite high in the upper reach of the estuary, inferred from antifouling paint on fishing boats of a local shipping company. According to established sediment quality guidelines, DDTs in the JRE posed potential ecological risk. HCHs in the estuary were mainly derived from the weathered HCHs preserved in the agriculture soils via local major river runoffs. OCPs patterns showed that OCPs in the south coast of WTS were resulted from local sources via river input, while OCPs in the north coast attributed to the long-range transport derived by the Fujian-Zhejiang Coastal Current. Minor variations of PCB concentrations and homologs indicated that PCBs were not the main pollutant in the agricultural region, consistent lighter PCBs reflected industrial PCBs were transported via atmospheric deposition derived by East Asia Monsoon. Moreover, the primary distribution pattern founded for DDTs and the considerable mass inventories and burdens calculated (258.1 ng cm -2 and 10.4 tones for OCPs) that higher than Pearl River Delta and Yangtze River Delta, together suggested that the contaminated sediments in the study area may be a potential source of OCPs to the global ocean. Copyright © 2016 Elsevier Ltd. All rights

Assessing natural and anthropogenic influences on water discharge and sediment load in the Yangtze River, China.

PubMed

Zhao, Yifei; Zou, Xinqing; Liu, Qing; Yao, Yulong; Li, Yali; Wu, Xiaowei; Wang, Chenglong; Yu, Wenwen; Wang, Teng

2017-12-31

The water discharge and sediment load of rivers are changing substantially under the impacts of climate change and human activities, becoming a hot issue in hydro-environmental research. In this study, the water discharge and sediment load in the mainstream and seven tributaries of the Yangtze River were investigated by using long-term hydro-meteorological data from 1953 to 2013. The non-parametric Mann-Kendall test and double mass curve (DMC) were used to detect trends and abrupt change-points in water discharge and sediment load and to quantify the effects of climate change and human activities on water discharge and sediment load. The results are as follows: (1) the water discharge showed a non-significant decreasing trend at most stations except Hukou station. Among these, water discharge at Dongting Lake and the Min River basin shows a significant decreasing trend with average rates of -13.93×10 8 m 3 /year and -1.8×10 8 m 3 /year (P<0.05), respectively. However, the sediment load exhibited a significant decreasing trend in all tributaries of the Yangtze River. (2) No significant abrupt change-points were detected in the time series of water discharge for all hydrological stations. In contrast, significant abrupt change-points were detected in sediment load, most of these changes appeared in the late 1980s. (3) The water discharge was mainly influenced by precipitation in the Yangtze River basin, whereas sediment load was mainly affected by climate change and human activities; the relative contribution ratios of human activities were above 70% for the Yangtze River. (4) The decrease of sediment load has directly impacted the lower Yangtze River and the delta region. These results will provide a reference for better resource management in the Yangtze River Basin. Copyright © 2017 Elsevier B.V. All rights reserved.

The role of extreme floods in estuary-coastal behaviour: contrasts between river- and tide-dominated microtidal estuaries

NASA Astrophysics Data System (ADS)

Cooper, J. A. G.

2002-06-01

Contrasting modes of sedimentation and facies arrangement in tide- and river-dominated microtidal estuaries arise from the degree to which river or tidal discharge and sediment supply influences an estuary. A distinct facies gradation exists in tide-dominated systems from sandy, barrier/tidal delta-associated environments at the coast through deep mud-dominated middle reaches to fluvial sediment in the upper reaches. In river-dominated systems, fluvial sediment extends to the barrier and flood-tidal deltas are poorly developed or absent from the estuary. A number of independent observations during extreme floods on the South African coast indicate that these types of estuary respond differently to extreme river floods and that the mode of response corresponds to estuary type. Tide-dominated systems exhibit preferential erosion of noncohesive barrier and tidal delta sediments during river floods while the middle reaches remain little modified. River-dominated systems experience consistent erosion throughout their channel length during extreme floods. The increased cohesion of riverine sediments and stabilisation of bars by vegetation in river-dominated channels means that higher magnitude floods are necessary to effect significant morphological change. Barrier erosion, including the tidal delta, results in deposition of an ephemeral delta composed almost entirely of sands from these deposits in tide-dominated estuaries. In river-dominated systems, eroded channel sediments and material from the river catchment may augment barrier sediments in the ephemeral delta deposit. Post-flood, wave-reworking of ephemeral delta sediments acts to restore barriers to pre-flood morphology within a few years; however, in river-dominated systems, the additional sediment volume may produce significant coastal progradation that requires several years or decades to redistribute. These different modes of flood response mediated by the nature of the estuary have implications for coastal

Revealing Sources and Distribution Changes of Dissolved Organic Matter (DOM) in Pore Water of Sediment from the Yangtze Estuary

PubMed Central

Wang, Ying; Zhang, Di; Shen, Zhenyao; Feng, Chenghong; Chen, Jing

2013-01-01

Dissolved organic matter (DOM) in sediment pore waters from Yangtze estuary of China based on abundance, UV absorbance, molecular weight distribution and fluorescence were investigated using a combination of various parameters of DOM as well as 3D fluorescence excitation emission matrix spectra (F-EEMS) with the parallel factor and principal component analysis (PARAFAC-PCA). The results indicated that DOM in pore water of Yangtze estuary was very variable which mainly composed of low aromaticity and molecular weight materials. Three humic-like substances (C1, C2, C4) and one protein-like substance (C3) were identified by PARAFAC model. C1, C2 and C4 exhibited same trends and were very similar. The separation of samples on both axes of the PCA showed the difference in DOM properties. C1, C2 and C4 concurrently showed higher positive factor 1 loadings, while C3 showed highly positive factor 2 loadings. The PCA analysis showed a combination contribution of microbial DOM signal and terrestrial DOM signal in the Yangtze estuary. Higher and more variable DOM abundance, aromaticity and molecular weight of surface sediment pore water DOM can be found in the southern nearshore than the other regions primarily due to the influence of frequent and intensive human activities and tributaries inflow in this area. The DOM abundance, aromaticity, molecular weight and fluorescence intensity in core of different depth were relative constant and increased gradually with depth. DOM in core was mainly composed of humic-like material, which was due to higher release of the sedimentary organic material into the porewater during early diagenesis. PMID:24155904

Effects of Yangtze River source water on genomic polymorphisms of male mice detected by RAPD.

PubMed

Zhang, Xiaolin; Zhang, Zongyao; Zhang, Xuxiang; Wu, Bing; Zhang, Yan; Yang, Liuyan; Cheng, Shupei

2010-02-01

In order to evaluate the environmental health risk of drinking water from Yangtze River source, randomly amplified polymorphic DNA (RAPD) markers were used to detect the effects of the source water on genomic polymorphisms of hepatic cell of male mice (Mus musculus, ICR). After the mice were fed with source water for 90 days, RAPD-polymerase chain reactions (PCRs) were performed on hepatic genomic DNA using 20 arbitrary primers. Totally, 189 loci were generated, including 151 polymorphic loci. On average, one PCR primer produced 5.3, 4.9 and 4.8 bands for each mouse in the control, the groups fed with source water and BaP solution, respectively. Compared with the control, feeding mice with Yangtze River source water caused 33 new loci to appear and 19 to disappear. Statistical analysis of RAPD printfingers revealed that Yangtze River source water exerted a significant influence on the hepatic genomic polymorphisms of male mice. This study suggests that RAPD is a reliable and sensitive method for the environmental health risk of Yangtze River source water.

[Spatio-temporal variations of origin, distribution and diffusion of Oncomelania hupensis in Yangtze River Basin].

PubMed

Deng, Chen; Li-Yong, Wen

2017-10-24

As the only intermediate host of Schistosoma japonicum, Oncomelania hupensis in China is mainly distributed in the Yangtze River Basin. The origin of the O. hupensis and the spatio-temporal variations of its distribution and diffusion in the Yangtze River Basin and the influencing factors, as well as significances in schistosomiasis elimination in China are reviewed in this paper.

An investigation of enhanced recessions in Poyang Lake: Comparison of Yangtze River and local catchment impacts

NASA Astrophysics Data System (ADS)

Zhang, Qi; Ye, Xu-chun; Werner, Adrian D.; Li, Yun-liang; Yao, Jing; Li, Xiang-hu; Xu, Chong-yu

2014-09-01

Changes in lake hydrological regimes and the associated impacts on water supplies and ecosystems are internationally recognized issues. During the past decade, the persistent dryness of Poyang Lake (the largest freshwater lake in China) has caused water supply and irrigation crises for the 12.4 million inhabitants of the region. There is conjecture as to whether this dryness is caused by climate variability and/or human activities. This study examines long-term datasets of catchment inflow and Lake outflow, and employs a physically-based hydrodynamic model to explore catchment and Yangtze River controls on the Lake's hydrology. Lake water levels fell to their lowest during 2001-2010 relative to previous decades. The average Lake size and volume reduced by 154 km2 and 11 × 108 m3 during the same period, compared to those for the preceding period (1970-2000). Model simulations demonstrated that the drainage effect of the Yangtze River was the primary causal factor. Modeling also revealed that, compared to climate variability impacts on the Lake catchment, modifications to Yangtze River flows from the Three Gorges Dam have had a much greater impact on the seasonal (September-October) dryness of the Lake. Yangtze River effects are attenuated in the Lake with distance from the River, but nonetheless propagate some 100 km to the Lake's upstream limit. Proposals to build additional dams in the upper Yangtze River and its tributaries are expected to impose significant challenges for the management of Poyang Lake. Hydraulic engineering to modify the flow regime between the Lake and the Yangtze River would somewhat resolve the seasonal dryness of the Lake, but will likely introduce other issues in terms of water quality and aquatic ecosystem health, requiring considerable further research.

Juvenile Salmon Usage of the Skeena River Estuary

PubMed Central

Carr-Harris, Charmaine; Gottesfeld, Allen S.; Moore, Jonathan W.

2015-01-01

Migratory salmon transit estuary habitats on their way out to the ocean but this phase of their life cycle is more poorly understood than other phases. The estuaries of large river systems in particular may support many populations and several species of salmon that originate from throughout the upstream river. The Skeena River of British Columbia, Canada, is a large river system with high salmon population- and species-level diversity. The estuary of the Skeena River is under pressure from industrial development, with two gas liquefaction terminals and a potash loading facility in various stages of environmental review processes, providing motivation for understanding the usage of the estuary by juvenile salmon. We conducted a juvenile salmonid sampling program throughout the Skeena River estuary in 2007 and 2013 to investigate the spatial and temporal distribution of different species and populations of salmon. We captured six species of juvenile anadromous salmonids throughout the estuary in both years, and found that areas proposed for development support some of the highest abundances of some species of salmon. Specifically, the highest abundances of sockeye (both years), Chinook in 2007, and coho salmon in 2013 were captured in areas proposed for development. For example, juvenile sockeye salmon were 2–8 times more abundant in the proposed development areas. Genetic stock assignment demonstrated that the Chinook salmon and most of the sockeye salmon that were captured originated from throughout the Skeena watershed, while some sockeye salmon came from the Nass, Stikine, Southeast Alaska, and coastal systems on the northern and central coasts of British Columbia. These fish support extensive commercial, recreational, and First Nations fisheries throughout the Skeena River and beyond. Our results demonstrate that estuary habitats integrate species and population diversity of salmon, and that if proposed development negatively affects the salmon populations

Estimation of nutrient discharge from the Yangtze River to the East China Sea and the identification of nutrient sources.

PubMed

Tong, Yindong; Bu, Xiaoge; Chen, Junyue; Zhou, Feng; Chen, Long; Liu, Maodian; Tan, Xin; Yu, Tao; Zhang, Wei; Mi, Zhaorong; Ma, Lekuan; Wang, Xuejun; Ni, Jing

2017-01-05

Based on a time-series dataset and the mass balance method, the contributions of various sources to the nutrient discharges from the Yangtze River to the East China Sea are identified. The results indicate that the nutrient concentrations vary considerably among different sections of the Yangtze River. Non-point sources are an important source of nutrients to the Yangtze River, contributing about 36% and 63% of the nitrogen and phosphorus discharged into the East China Sea, respectively. Nutrient inputs from non-point sources vary among the sections of the Yangtze River, and the contributions of non-point sources increase from upstream to downstream. Considering the rice growing patterns in the Yangtze River Basin, the synchrony of rice tillering and the wet seasons might be an important cause of the high nutrient discharge from the non-point sources. Based on our calculations, a reduction of 0.99Tg per year in total nitrogen discharges from the Yangtze River would be needed to limit the occurrences of harmful algal blooms in the East China Sea to 15 times per year. The extensive construction of sewage treatment plants in urban areas may have only a limited effect on reducing the occurrences of harmful algal blooms in the future. Copyright © 2016 Elsevier B.V. All rights reserved.

Impacts of large dams on the complexity of suspended sediment dynamics in the Yangtze River

NASA Astrophysics Data System (ADS)

Wang, Yuankun; Rhoads, Bruce L.; Wang, Dong; Wu, Jichun; Zhang, Xiao

2018-03-01

The Yangtze River is one of the largest and most important rivers in the world. Over the past several decades, the natural sediment regime of the Yangtze River has been altered by the construction of dams. This paper uses multi-scale entropy analysis to ascertain the impacts of large dams on the complexity of high-frequency suspended sediment dynamics in the Yangtze River system, especially after impoundment of the Three Gorges Dam (TGD). In this study, the complexity of sediment dynamics is quantified by framing it within the context of entropy analysis of time series. Data on daily sediment loads for four stations located in the mainstem are analyzed for the past 60 years. The results indicate that dam construction has reduced the complexity of short-term (1-30 days) variation in sediment dynamics near the structures, but that complexity has actually increased farther downstream. This spatial pattern seems to reflect a filtering effect of the dams on the on the temporal pattern of sediment loads as well as decreased longitudinal connectivity of sediment transfer through the river system, resulting in downstream enhancement of the influence of local sediment inputs by tributaries on sediment dynamics. The TGD has had a substantial impact on the complexity of sediment series in the mainstem of the Yangtze River, especially after it became fully operational. This enhanced impact is attributed to the high trapping efficiency of this dam and its associated large reservoir. The sediment dynamics "signal" becomes more spatially variable after dam construction. This study demonstrates the spatial influence of dams on the high-frequency temporal complexity of sediment regimes and provides valuable information that can be used to guide environmental conservation of the Yangtze River.

Genomic evidence for the population genetic differentiation of Misgurnus anguillicaudatus in the Yangtze River basin of China.

PubMed

Yi, Shaokui; Wang, Weimin; Zhou, Xiaoyun

2018-02-21

Misgurnus anguillicaudatus, an important aquatic species, is mainly distributed in the Yangtze River basin. To reveal the population genetic structure of M. anguillicaudatus distributed in the Yangtze River basin, genotyping by sequencing (GBS) technique was employed to detect the genome wide genetic variations of M. anguillicaudatus. A total of 30.03 Gb raw data were yielded from 70 samples collected from 15 geographic sites located in the Yangtze River basin. Subsequently, 2092 high quality SNPs were genotyped across these samples and used for a series of genetic analysis. The results of genetic analysis showed that high levels of genetic diversity were observed and the populations from upper reaches (UR) were significantly differentiated from the middle and lower reaches (MLR) of Yangtze River basin. Meanwhile, no significant isolation by distance was detected among the populations. Ecological factors (e.g. complicated topography and climatic environment) and anthropogenic factors (e.g. aquaculture and agriculture cultivation) might account for the genetic disconnectivity between UR and MLR populations. This study provided valuable genetic data for the future breeding program and also for the conversation and scientific utilization of those abundant genetic resources stored in the Yangtze River basin. Copyright © 2018 Elsevier Inc. All rights reserved.

Forecasting the Amount of Waste-Sewage Water Discharged into the Yangtze River Basin Based on the Optimal Fractional Order Grey Model.

PubMed

Li, Shuliang; Meng, Wei; Xie, Yufeng

2017-12-23

With the rapid development of the Yangtze River economic belt, the amount of waste-sewage water discharged into the Yangtze River basin increases sharply year by year, which has impeded the sustainable development of the Yangtze River basin. The water security along the Yangtze River basin is very important for China, It is something aboutwater security of roughly one-third of China's population and the sustainable development of the 19 provinces, municipalities and autonomous regions among the Yangtze River basin. Therefore, a scientific prediction of the amount of waste-sewage water discharged into Yangtze River basin has a positive significance on sustainable development of industry belt along with Yangtze River basin. This paper builds the fractional DWSGM(1,1)(DWSGM(1,1) model is short for Discharge amount of Waste Sewage Grey Model for one order equation and one variable) model based on the fractional accumulating generation operator and fractional reducing operator, and calculates the optimal order of "r" by using particle swarm optimization(PSO)algorithm for solving the minimum average relative simulation error. Meanwhile, the simulation performance of DWSGM(1,1)model with the optimal fractional order is tested by comparing the simulation results of grey prediction models with different orders. Finally, the optimal fractional order DWSGM(1,1)grey model is applied to predict the amount of waste-sewage water discharged into the Yangtze River basin, and corresponding countermeasures and suggestions are put forward through analyzing and comparing the prediction results. This paper has positive significance on enriching the fractional order modeling method of the grey system.

Forecasting the Amount of Waste-Sewage Water Discharged into the Yangtze River Basin Based on the Optimal Fractional Order Grey Model

PubMed Central

Li, Shuliang; Meng, Wei; Xie, Yufeng

2017-01-01

With the rapid development of the Yangtze River economic belt, the amount of waste-sewage water discharged into the Yangtze River basin increases sharply year by year, which has impeded the sustainable development of the Yangtze River basin. The water security along the Yangtze River basin is very important for China, It is something about water security of roughly one-third of China’s population and the sustainable development of the 19 provinces, municipalities and autonomous regions among the Yangtze River basin. Therefore, a scientific prediction of the amount of waste-sewage water discharged into Yangtze River basin has a positive significance on sustainable development of industry belt along with Yangtze River basin. This paper builds the fractional DWSGM (1,1) (DWSGM (1,1) model is short for Discharge amount of Waste Sewage Grey Model for one order equation and one variable) model based on the fractional accumulating generation operator and fractional reducing operator, and calculates the optimal order of “r” by using particle swarm optimization (PSO) algorithm for solving the minimum average relative simulation error. Meanwhile, the simulation performance of DWSGM (1,1) model with the optimal fractional order is tested by comparing the simulation results of grey prediction models with different orders. Finally, the optimal fractional order DWSGM (1,1) grey model is applied to predict the amount of waste-sewage water discharged into the Yangtze River basin, and corresponding countermeasures and suggestions are put forward through analyzing and comparing the prediction results. This paper has positive significance on enriching the fractional order modeling method of the grey system. PMID:29295517

Nekton use of intertidal creek edges in low salinity salt marshes of the Yangtze River estuary along a stream-order gradient

NASA Astrophysics Data System (ADS)

Jin, Binsong; Qin, Haiming; Xu, Wang; Wu, Jihua; Zhong, Junsheng; Lei, Guangchun; Chen, Jiakuan; Fu, Cuizhang

2010-07-01

Non-vegetated creek edges were investigated to explore spatial nekton use patterns in a low salinity intertidal salt marsh creek network of the Yangtze River estuary along a stream-order gradient with four creek orders. Non-vegetated creek edges were arbitrarily defined as the approximately 3 m extending from the creek bank (the marsh-creek interface) into open water. Nekton was sampled using seine nets during daytime high slack water during spring tides for two or three days each in May through July 2008. Twenty-three nekton species (16 fishes and 7 crustaceans) were caught during the study. Fishes were dominated by gobies ( Mugilogobius abei, Periophthalmus magnuspinnatus, Periophthalmus modestus, Synechogobius ommaturus), mullets ( Chelon haematocheilus, Liza affinis) and Chinese sea bass ( Lateolabrax maculatus). Crustaceans were dominated by mud crab ( Helice tientsinensis) and white prawn ( Exopalaemon carinicauda). Rank abundance curves revealed higher evenness of nekton assemblages in lower-order creeks compared to higher-order creeks. Fish abundance tended to increase with increasing creek order. Crustacean abundance was higher in the first-third order creeks than in the fourth-order creek. Dominant nekton species displayed various trends in abundance and length-frequency distributions along the stream-order gradient. The spatial separation of nekton assemblages between the first-third order creeks and the fourth-order creek could be attributed to geomorphological factors (distance to mouth and cross-sectional area). These findings indicate that both lower- and higher-order creek edges play important yet different roles for nekton species and life history stages in salt marshes.

Water mass interaction in the confluence zone of the Daning River and the Yangtze River--a driving force for algal growth in the Three Gorges Reservoir.

PubMed

Holbach, Andreas; Wang, Lijing; Chen, Hao; Hu, Wei; Schleicher, Nina; Zheng, Binghui; Norra, Stefan

2013-10-01

Increasing eutrophication and algal bloom events in the Yangtze River Three Gorges Reservoir, China, are widely discussed with regard to changed hydrodynamics and nutrient transport and distribution processes. Insights into water exchange and interaction processes between water masses related to large-scale water level fluctuations in the reservoir are crucial to understand water quality and eutrophication dynamics. Therefore, confluence zones of tributaries with the Yangtze River main stream are dedicated key interfaces. In this study, water quality data were recorded in situ and on-line in varying depths with the MINIBAT towed underwater multi-sensor system in the confluence zone of the Daning River and the Yangtze River close to Wushan City during 1 week in August 2011. Geostatistical evaluation of the water quality data was performed, and results were compared to phosphorus contents of selective water samples. The strongly rising water level throughout the measurement period caused Yangtze River water masses to flow upstream into the tributary and supply their higher nutrient and particulate loads into the tributary water body. Rapid algal growth and sedimentation occurred immediately when hydrodynamic conditions in the confluence zone became more serene again. Consequently, water from the Yangtze River main stream can play a key role in providing nutrients to the algal bloom stricken water bodies of its tributaries.

Seasonal atmospheric deposition and air-sea gaseous exchange of polycyclic aromatic hydrocarbons over the Yangtze River Estuary, East China Sea: Implication for the source-sink processes

NASA Astrophysics Data System (ADS)

Jiang, Y.; Guo, Z.

2017-12-01

As the home of the largest port in the world, the Yangtze River Estuary (YRE) in the East China Sea (ECS) is adjacent to the largest economic zone in China with more than 10% of Chinese population and provides one-fifth of national GDP. The YRE is under the path of contaminated East Asian continental outflow. These make the YRE unique for the pollutant biogeochemical cycling in the world. In this work, 94 pairs of air samples and 20 surface seawater samples covering four seasons were collected from a remote receptor site in the YRE from March 2014 to January 2015, in order to explore the seasonal fluxes of air-sea gaseous exchange and atmospheric dry and wet deposition of 15 polycyclic aromatic hydrocarbons (PAHs) and their source-sink processes at the air-sea interface. The average dry and wet deposition fluxes of 15 PAHs were estimated as 879 ± 1393 ng m-2 d-1 and 755 ± 545 ng m-2 d-1, respectively. The gaseous PAHs were released from seawater to atmosphere during the whole year with an average of 3039 ± 2030 ng m-2 d-1. The gaseous exchange of PAHs was referred as the dominant process at the air-sea interface in the YRE as the magnitude of volatilization flux of PAHs exceeded that of the total dry and wet deposition. The gaseous PAH exchange flux was dominated by 3-ring PAHs, with the highest value in summer while lowest in winter, depicting a strong seasonal variation due to temperature, wind speed and air-sea concentration gradient difference among seasons. Based on the simplified mass balance estimation, net 9.6 tons/y of PAHs was volatilized from seawater to atmosphere with an area of approximately 20000 km2 in the YRE. Apart from Yangtze River input and ocean ship emissions in the entire year, the selective release of low molecular weight PAHs from sediments in winter due to re-suspension triggered by the East Asian winter monsoon could be another possible source for dissolved PAHs. This work suggests that the source-sink processes of PAHs at air

The influence of seasonal climate on the morphology of the mouth-bar in the Yangtze Estuary, China

NASA Astrophysics Data System (ADS)

Zhang, Min; Townend, Ian; Cai, Huayang; He, Jiawei; Mei, Xuefei

2018-02-01

The geomorphology of the Yangtze Estuary in the Changjiang River Delta in Eastern China has been the subject of extensive research. This study extends previous work to examine the influence of wind-waves on the mouth-bar, where about half of the river-borne material settles to the bed. The site is located just outside of Changjiang River mouth, which is meso-tidal and subject to seasonally varying river flows and wind-wave conditions. Modeling was performed with a coupled wave-current hydrodynamic model using TELEMAC and TOMAWAC and validated against observed data. Bottom Shear Stress (BSS) from river, tide and waves based on the numerical model output was used to infer the respective contribution to the evolution of the subaqueous delta. Our examination did not however extend to modeling the sediment transport or the morphological bed changes. The results suggest that (i) the dominance of river discharge is limited to an area inside the mouth, while outside, the mouth-bar is tide-wave dominant; (ii) considering just the tide, the currents on the shallow shoals are flood dominant and deep channels are ebb dominant, which induces continued accretion over the shallows and erodes the deeper parts of the mouth-bar until the tidal currents become too weak to transport sediment; (iii) whereas waves are very efficient at reshaping the shallow shoals, with the effect being subtly dependent on the depth distribution over the mouth-bar; (iv) the stability of shallow shoal morphology is highly dependent on the presence of seasonal wind-waves and characterized as "summer storing and winter erosion", while deep channels perform like corridors of water and sediment, exporting sediment all year round. The nature of the mouth-bar response has important implications for coastal management, such as the ongoing deep water channel maintenance, reclamations and coastal defense measures.

Outbreaks of the Brown Planthopper Nilaparvata lugens (Stål) in the Yangtze River Delta: Immigration or Local Reproduction?

PubMed Central

Zhai, Bao-Ping; Lu, Ming-Hong; Liu, Wan-Cai; Zhu, Feng; Wu, Xiang-Wen; Chen, Gui-Hua; Zhang, Xiao-Xi

2014-01-01

An effective control strategy for migratory pests is difficult to implement because the cause of infestation (i.e., immigration or local reproduction) is often not established. In particular, the outbreak mechanisms of the brown planthopper, Nilaparvata lugens (Stål), an insect causing massive losses in rice fields in the Yangtze River Delta in China, are frequently unclear. Field surveys of N. lugens were performed in Jiangsu and Zhejiang Provinces in 2008 to 2010 and related historical data from 2003 onwards were collected and analyzed to clarify the cause of these infestations. Results showed that outbreaks of N. lugens in the Yangtze River Delta were mostly associated with an extremely high increase in population. Thus, reproduction rather than immigration from distant sources were the cause of the infestations. Although mass migration occurred late in the season (late August and early September), the source areas of N. lugens catches in the Yangtze River Delta were mainly located in nearby areas, including the Yangtze River Delta itself, Anhui and northern Jiangxi Provinces. These regions collectively form the lower-middle reaches of the Yangtze River, and the late migration can thus be considered as an internal bioflow within one population. PMID:24558459

Outbreaks of the brown planthopper Nilaparvata lugens (Stål) in the Yangtze River Delta: immigration or local reproduction?

PubMed

Hu, Gao; Lu, Fang; Zhai, Bao-Ping; Lu, Ming-Hong; Liu, Wan-Cai; Zhu, Feng; Wu, Xiang-Wen; Chen, Gui-Hua; Zhang, Xiao-Xi

2014-01-01

An effective control strategy for migratory pests is difficult to implement because the cause of infestation (i.e., immigration or local reproduction) is often not established. In particular, the outbreak mechanisms of the brown planthopper, Nilaparvata lugens (Stål), an insect causing massive losses in rice fields in the Yangtze River Delta in China, are frequently unclear. Field surveys of N. lugens were performed in Jiangsu and Zhejiang Provinces in 2008 to 2010 and related historical data from 2003 onwards were collected and analyzed to clarify the cause of these infestations. Results showed that outbreaks of N. lugens in the Yangtze River Delta were mostly associated with an extremely high increase in population. Thus, reproduction rather than immigration from distant sources were the cause of the infestations. Although mass migration occurred late in the season (late August and early September), the source areas of N. lugens catches in the Yangtze River Delta were mainly located in nearby areas, including the Yangtze River Delta itself, Anhui and northern Jiangxi Provinces. These regions collectively form the lower-middle reaches of the Yangtze River, and the late migration can thus be considered as an internal bioflow within one population.

Anthropogenic tritium in the Loire River estuary, France

NASA Astrophysics Data System (ADS)

Péron, O.; Gégout, C.; Reeves, B.; Rousseau, G.; Montavon, G.; Landesman, C.

2016-12-01

This work is carried out in the frame of a radioecological monitoring of anthropogenic tritium from upstream and downstream of several nuclear power plants along the Loire River to its estuary. This paper studies the variation of anthropogenic tritium species in the Loire River system from upstream to the mouth of the estuary. Tritiated water (HTO and HTO in sediment pore water) and organically bound tritium (OBT) forms were analysed after dedicated pre-treatments. The collected environmental samples consist in (i) surface-sediment and core samples from the river floor, (ii) surface and water column samples. A maximum 3H activity concentration of 26 ± 3 Bq·L- 1 in the Loire River estuary is obtained whereas an environmental background level around 1 Bq·L- 1 is determined for a non influenced continental area by anthropogenic activities. The European follow-up indicator used as a screening value is 100 Bq·L- 1. The conservative tritium behaviour was used in order to characterize the tidal regime and river flow influences in the mixing zone of the Loire River estuary. Furthermore, OBT levels and total organically carbon (TOC) content are explored. Finally, ratios of OBT relative to HTO in sediment pore water in surface-sediment and core samples are also discussed.

[Shifting path of industrial pollution gravity centers and its driving mechanism in Pan-Yangtze River Delta].

PubMed

Zhao, Hai-Xia; Jiang, Xiao-Wei; Cui, Jian-Xin

2014-11-01

Shifting path of industrial pollution gravity centers is the response of environmental special formation during the industry transfer process, in order to prove the responding of industrial pollution gravity centers to industry transfer in economically developed areas, this paper calculates the gravity centers of industrial wastewater, gas and solid patterns and reveals the shifting path and its driving mechanism, using the data of industrial pollution in the Pan-Yangtze River Delta from 2000 to 2010. The results show that the gravity center of the industrial waste in Pan-Yangtze River Delta shifts for sure in the last 10 years, and gravity center of solid waste shifts the maximum distance within the three wastes, which was 180.18 km, and shifting distances for waste gas and waste water were 109.51 km and 85.92 km respectively. Moreover, the gravity center of the industrial waste in Pan-Yangtze River Delta shifts westwards, and gravity centers of waste water, gas and solid shift for 0.40 degrees, 0.17 degrees and 0.03 degrees respectively. The shifting of industrial pollution gravity centers is driven by many factors. The rapid development of the heavy industry in Anhui and Jiangxi provinces results in the westward shifting of the pollutions. The optimization and adjustment of industrial structures in Yangtze River Delta region benefit to alleviating industrial pollution, and high-polluting industries shifted to Anhui and Jiangxi provinces promotes pollution gravity center shifting to west. While the development of massive clean enterprise, strong environmental management efforts and better environmental monitoring system slow the shifting trend of industrial pollution to the east in Yangtze River Delta. The study of industrial pollution gravity shift and its driving mechanism provides a new angle of view to analyze the relationship between economic development and environmental pollution, and also provides academic basis for synthetical management and control of

Variation in MERRA-2 aerosol optical depth over the Yangtze River Delta from 1980 to 2016

NASA Astrophysics Data System (ADS)

Sun, Enwei; Che, Huizheng; Xu, Xiaofeng; Wang, Zhenzhu; Lu, Chunsong; Gui, Ke; Zhao, Hujia; Zheng, Yu; Wang, Yaqiang; Wang, Hong; Sun, Tianze; Liang, Yuanxin; Li, Xiaopan; Sheng, Zhizhong; An, Linchang; Zhang, Xiaoye; Shi, Guangyu

2018-05-01

In this study, 765 instantaneous MERRA-2 (second Modern-Era Retrospective analysis for Research and Applications) aerosol optical depth (AOD) values at 550 nm were compared with those of a sky radiometer in Hefei (31.90° N, 117.17° E) for the different seasons from March 2007 to February 2010. The correlation coefficients (R) were 0.88, 0.83, 0.88, and 0.80 in spring, summer, autumn, and winter, respectively. The MERRA-2 AOD is also compared with MODIS Aqua AOD in the entire Yangtze River Delta, and good agreement has been obtained. The MERRA-2 AOD product was used to analyze the spatial distribution and temporal variation of the annual, seasonal and monthly means of the AOD over the Yangtze River Delta region from 1980 to 2016 (37 years). The mean values of the MERRA-2 AOD during the study period show that the AOD (between 0.45 and 0.55) in the northern area of the Yangtze River Delta was higher than that (between 0.30 and 0.45) of the southern area. The northwest part of the Yangtze River Delta had the highest mean AOD values (between 0.50 and 0.55). The AOD increased slowly in the 1980s and 1990s, followed by a rapid increase between 2001 and 2010. An AOD decrease can be seen from 2011 to 2016. The mean AOD in each month is discussed. High AOD was observed in March, April, and June, while low AOD could be seen in September, October, November, and December. Three different area types (large cities, medium-sized cities, and remote areas) had nearly the same annual AOD variation. Large cities had the highest AOD (about 0.48), while remote areas had the lowest (about 0.42). In summer, the AOD in remote areas was much lower than that in cities. The AOD variational trend over the Yangtze River Delta was studied during two periods. The increasing trend could be seen over the entire Yangtze River Delta in each month from 1980 to 2009. A decreasing trend was found all over the Yangtze River Delta in January, February, March, July, October, and November, whereas in

Climate Drivers of Spatiotemporal Variability of Precipitation in the Source Region of Yangtze River

NASA Astrophysics Data System (ADS)

Du, Y.; Berndtsson, R.; An, D.; Yuan, F.

2017-12-01

Variability of precipitation regime has significant influence on the environment sustainability in the source region of Yangtze River, especially when the vegetation degradation and biodiversity reduction have already occurred. Understanding the linkage between variability of local precipitation and global teleconnection patterns is essential for water resources management. Based on physical reasoning, indices of the climate drivers can provide a practical way of predicting precipitation. Due to high seasonal variability of precipitation, climate drivers of the seasonal precipitation also varies. However, few reports have gone through the teleconnections between large scale patterns with seasonal precipitation in the source region of Yangtze River. The objectives of this study are therefore (1) assessment of temporal trend and spatial variability of precipitation in the source region of Yangtze River; (2) identification of climate indices with strong influence on seasonal precipitation anomalies; (3) prediction of seasonal precipitation based on revealed climate indices. Principal component analysis and Spearman rank correlation were used to detect significant relationships. A feed-forward artificial neural network(ANN) was developed to predict seasonal precipitation using significant correlated climate indices. Different influencing climate indices were revealed for precipitation in each season, with significant level and lag times. Significant influencing factors were selected to be the predictors for ANN model. With correlation coefficients between observed and simulated precipitation over 0.5, the results were eligible to predict the precipitation of spring, summer and winter using teleconnections, which can improve integrated water resources management in the source region of Yangtze River.

LOWER COLUMBIA RIVER ESTUARY PROGRAM COMPREHENSIVE CONSERVATION AND MANAGEMENT PLAN

EPA Science Inventory

An estuary is the area where the fresh water of a river meets the salt water of an ocean. In the Columbia River system, this occurs in the lower 46 river miles. In an estuary, the river has a direct, natural connection with the open sea. This transition from fresh to salt water c...

Solanaceae plant malformation in Chongqing City, China, reveals a pollution threat to the Yangtze River.

PubMed

Zhang, Hongbo; Liu, Guanshan; Timko, Michael P; Li, Jiana; Wang, Wenjing; Ma, Haoran

2014-10-21

Water quality is under increasing threat from industrial and natural sources of pollutants. Here, we present our findings about a pollution incident involving the tap water of Chongqing City in China. In recent years, Solanaceae plants grown in greenhouses in this city have displayed symptoms of cupped, strappy leaves. These symptoms resembled those caused by chlorinated auxinic herbicides. We have determined that these symptoms were caused by the tap water used for irrigation. Using a bioactivity-guided fractionation method, we isolated a substance with corresponding auxinic activity from the tap water. The substance was named "solanicide" because of its strong bioactivity against Solanaceae plants. Further investigation revealed that the solanicide in the water system of Chongqing City is derived from the Jialing River, a major tributary of the Yangtze River. Therefore, it is also present in the Yangtze River downstream of Chongqing after the inflow of the Jialing River. Biological analyses indicated that solanicide is functionally similar to, but distinct from, other known chlorinated auxinic herbicides. Chemical assays further showed that solanicide structurally differs from those compounds. This study has highlighted a water pollution threat to the Yangtze River and its floodplain ecosystem.

Age Tracers and Residence Time in the Hudson River Estuary

NASA Astrophysics Data System (ADS)

Nadell, S. A.; Geyer, W. R.; Wang, T.

2016-02-01

The Hudson River is one of the most nutrient loaded rivers in the country, however phytoplankton bloom do not occur, possibly as a result of how quickly water moves though the Hudson River estuary. Slower water residence times may then allow for significant phytoplankton growth. Water age and residence time, which are compliments of one another under stead-state conditions, are important factors in determining where phytoplankton move and how long they spend within a favorable portion of the estuary. This research involved introducing a freshwater and saltwater age tracer into the Regional Ocean Modeling System (ROMS) for the Hudson River estuary domain to observe the distribution of ages within the spring-neap tidal cycle and across different river discharge rates. These discharge rates represented average (500 m3/s), relatively high (1000 m3/s), and relatively low (200 m3/s) river flow conditions for the Hudson River. Saltwater age followed a distribution similar to salinity, while freshwater age distribution mostly represented river transit time. Under steady state conditions, combined freshwater and saltwater age may be used to calculate a rough estimate of estuary residence time. The results show that the residence time of the full estuary appears to be at greater than the doubling time of phytoplankton for all discharge rates and by over five days for even the relatively high discharge case. This leads to the conclusion that other estuary factors, including light availability and salinity, may be more important for limiting phytoplankton growth than residence time.

Scanning vertical distributions of typical aerosols along the Yangtze River using elastic lidar.

PubMed

Fan, Shidong; Liu, Cheng; Xie, Zhouqing; Dong, Yunsheng; Hu, Qihou; Fan, Guangqiang; Chen, Zhengyi; Zhang, Tianshu; Duan, Jingbo; Zhang, Pengfei; Liu, Jianguo

2018-07-01

In recent years, China has experienced heavy air pollution, especially haze caused by particulate matter (PM). The compositions, horizontal distributions, transport, and chemical formation mechanisms of PM and its precursors have been widely investigated in China based on near-ground measurements. However, the understanding of the distributions and physical and chemical processes of PM in the vertical direction remains limited. In this study, an elastic lidar was employed to investigate the vertical profiles of aerosols along the Yangtze River during the Yangtze River Campaign of winter 2015. Some typical aerosols were identified and some events were analyzed in three cases. Dust aerosols can be transported from the Gobi Desert to the Yangtze River basin across a long distance at both low and high altitudes in early December. The transport route was perpendicular to the ship track, suggesting that the dust aerosols may have affected a large area. Moreover, during transport, some dust was also affected by the areas below its transport route since some anthropogenic pollutants were mixed with the dust and changed some of its optical properties. Biomass-burning aerosols covering a distant range along the Yangtze River were identified. This result directly shows the impact areas of biomass-burning aerosols in some agricultural fields. Some directly emitted aerosol plumes were observed, and direct effects of such plumes were limited both temporally and spatially. In addition, an aerosol plume with very low linear depolarization ratios, probably formed through secondary processes, was also observed. These results can help us better understand aerosols in large spatial scales in China and can be useful to regional haze studies. Copyright © 2018. Published by Elsevier B.V.

Bioanalytical and instrumental analysis of estrogenic activities in drinking water sources from Yangtze River Delta.

PubMed

Hu, Xinxin; Shi, Wei; Cao, Fu; Hu, Guanjiu; Hao, Yingqun; Wei, Si; Wang, Xinru; Yu, Hongxia

2013-02-01

The estrogenic activities of source water from Yangtze River, Huaihe River, Taihu Lake and groundwater in Yangtze River Delta in the dry and wet season were determined by use of reporter gene assays based on African green monkey kidney (CV-1) cell lines. Higher estrogenic activities were observed in the dry season, and the estrogenic potentials in water samples from Taihu Lake were greater than other river basins. None of the samples from groundwater showed estrogen receptor (ER) agonist activity. The 17β-Estradiol (E2) equivalents (EEQs) of water samples in the dry season ranged from 9.41×10(-1) to 1.20×10(1) ng E2 L(-1). In the wet season, EEQs of all the water samples were below the detection limit as 9.00×10(-1) ng E2 L(-1) except for one sample from Huaihe River. The highest contribution of E2 was detected in Yangtze River as 99% of estrogenic activity. Nonylphenol (NP, 100% detection rate) and octylphenol (OP, 100% detection rate) might also be responsible for the estrogenic activities in water sources. Potential health risk induced by the estrogenic chemicals in source water may be posed to the residents through water drinking. Copyright © 2012 Elsevier Ltd. All rights reserved.

Multi-timescale sediment responses across a human impacted river-estuary system

NASA Astrophysics Data System (ADS)

Chen, Yining; Chen, Nengwang; Li, Yan; Hong, Huasheng

2018-05-01

Hydrological processes regulating sediment transport from land to sea have been widely studied. However, anthropogenic factors controlling the river flow-sediment regime and subsequent response of the estuary are still poorly understood. Here we conducted a multi-timescale analysis on flow and sediment discharges during the period 1967-2014 for the two tributaries of the Jiulong River in Southeast China. The long-term flow-sediment relationship remained linear in the North River throughout the period, while the linearity showed a remarkable change after 1995 in the West River, largely due to construction of dams and reservoirs in the upland watershed. Over short timescales, rainstorm events caused the changes of suspended sediment concentration (SSC) in the rivers. Regression analysis using synchronous SSC data in a wet season (2009) revealed a delayed response (average 5 days) of the estuary to river input, and a box-model analysis established a quantitative relationship to further describe the response of the estuary to the river sediment input over multiple timescales. The short-term response is determined by both the vertical SSC-salinity changes and the sediment trapping rate in the estuary. However, over the long term, the reduction of riverine sediment yield increased marine sediments trapped into the estuary. The results of this study indicate that human activities (e.g., dams) have substantially altered sediment delivery patterns and river-estuary interactions at multiple timescales.

A comparative study of the flux and fate of the Mississippi and Yangtze river sediments

NASA Astrophysics Data System (ADS)

Xu, K.; Yang, S. L.

2015-03-01

Large rivers play a key role in delivering water and sediment into the global oceans. Large-river deltas and associated coastlines are important interfaces for material fluxes that have a global impact on marine processes. In this study, we compare water and sediment discharge from Mississippi and Yangtze rivers by assessing: (1) temporal variation under varying climatic and anthropogenic impacts, (2) delta response of the declining sediment discharge, and (3) deltaic lobe switching and Holocene sediment dispersal patterns on the adjacent continental shelves. Dam constructions have decreased both rivers' sediment discharge significantly, leading to shoreline retreat along the coast. The sediment dispersal of the river-dominated Mississippi Delta is localized but for the tide-dominated Yangtze Delta is more diffuse and influenced by longshore currents. Sediment declines and relative sea level rises have led to coastal erosion, endangering the coasts of both rivers.

Exhumation Reconstruction of the Xiangcheng Area, SE Tibetan Plateau. Implication on the Evolution of the Yangtze River in the Cenozoic.

NASA Astrophysics Data System (ADS)

Gourbet, L.; Yang, R.; Fellin, M. G.; Gong, J.; Maden, C.

2016-12-01

Geodynamic processes associated with timing of river incision and river network reorganization on the Tibetan plateau margins remain controversial. In particular, hydrographic network modifications in SE Tibet have been interpreted as related with regional-scale uplift or fault motion. The paleocourse of the upper Yangtze river (Jinsha Sha) and the timing of the establishment of its modern course are highly debated, leading to conflicting models of the plateau evolution. For example, estimated ages for the formation of the Yangtze first bend (where the river shifts from flowing southward to northward) range from the Eocene to the Pliocene. River incision can be reconstructed using low-temperature thermochronometry. However, the lack of suitable rocks along the main riverbed of the Yangtze makes it challenging. To address this problem, we perform a local study of the Xiangcheng area, located in Sichuan, about 150 km upstream of the first bend and drained by tributaries of the upper Yangtze. We combine a tectono-geomorphic analysis to a reconstruction of exhumation rates using (U-Th-Sm)/He thermochronometry. The study area is characterized by the NW-SE trending, active left-lateral Xiangcheng fault, which is attested by crustal-depth seismic activity. Importantly, the courses of two tributaries of the Yangtze are deflected along the Xiangcheng fault, suggesting that the fault partly controls the evolution of the upper Yangtze course. Locally, the fault also exhibits triangular facets, suggesting normal motion probably related to the fault segmentation. Granite samples from the Xiangcheng pluton were collected along three altitudinal profiles and analyzed using zircon and apatite (U-Th-Sm)/He thermochronometry. We will discuss the results and their implications on exhumation and on the Yangtze river history during the Cenozoic.

East Asian Summer Monsoon Rainfall: A Historical Perspective of the 1998 Flood over Yangtze River

NASA Technical Reports Server (NTRS)

Weng, H.-Y.; Lau, K.-M.

1999-01-01

One of the main factors that might have caused the disastrous flood in China during 1998 summer is long-term variations that include a trend indicating increasing monsoon rainfall over the Yangtze River Valley. China's 160-station monthly rainfall anomaly for the summers of 1955-98 is analyzed for exploring such long-term variations. Singular value decomposition (SVD) between the summer rainfall and the global sea surface temperature (SST) anomalies reveals that the rainfall over Yangtze River Valley is closely related to global and regional SST variabilities at both interannual and interdecadal timescales. SVD1 mode links the above normal rainfall condition in central China to an El Nino-like SSTA distribution, varying on interannual timescale modified by a trend during the period. SVD3 mode links positive rainfall anomaly in Yangtze River Valley to the warm SST anomaly in the subtropical western Pacific, varying on interannual timescales modified by interdecadal timescales. This link tends to be stronger when the Nino3 area becomes colder and the western subtropical Pacific becomes warmer. The 1998 summer is a transition season when the 1997/98 El Nino event was in its decaying phase, and the SST in the Nino3 area emerged below normal anomaly while the subtropical western Pacific SST above normal. Thus, the first and third SVD modes become dominant in 1998 summer, favoring more Asian summer monsoon rainfall over the Yangtze River Valley.

Nitrogen Fixation in the Intertidal Sediments of the Yangtze Estuary: Occurrence and Environmental Implications

NASA Astrophysics Data System (ADS)

Hou, Lijun; Wang, Rong; Yin, Guoyu; Liu, Min; Zheng, Yanling

2018-03-01

Nitrogen fixation is a microbial-mediated process converting atmospheric dinitrogen gas to biologically available ammonia or other molecules, and it plays an important role in regulating nitrogen budgets in coastal marine ecosystems. In this study, nitrogen fixation in the intertidal sediments of the Yangtze Estuary was investigated using nitrogen isotope tracing technique. The abundance of nitrogen fixation functional gene (nifH) was also quantified. The measured rates of sediment nitrogen fixation ranged from 0.37 to 7.91 nmol N g-1 hr-1, while the abundance of nifH gene varied from 2.28 × 106 to 1.28 × 108 copies g-1 in the study area. The benthic nitrogen fixation was correlated closely to the abundance of nifH gene and was affected significantly by salinity, pH, and availability of sediment organic carbon and ammonium. It is estimated that sediment nitrogen fixation contributed approximately 9.3% of the total terrigenous inorganic nitrogen transported annually into the Yangtze estuarine and coastal environment. This result implies that the occurrence of benthic nitrogen fixation acts as an important internal source of reactive nitrogen and to some extent exacerbates nitrogen pollution in this aquatic ecosystem.

Improving estuary models by reducing uncertainties associated with river flows

NASA Astrophysics Data System (ADS)

Robins, Peter E.; Lewis, Matt J.; Freer, Jim; Cooper, David M.; Skinner, Christopher J.; Coulthard, Tom J.

2018-07-01

To mitigate against future changes to estuaries such as water quality, catchment and estuary models can be coupled to simulate the transport of harmful pathogenic viruses, pollutants and nutrients from their terrestrial sources, through the estuary and to the coast. To predict future changes to estuaries, daily mean river flow projections are typically used. We show that this approach cannot resolve higher frequency discharge events that have large impacts to estuarine dilution, contamination and recovery for two contrasting estuaries. We therefore characterise sub-daily scale flow variability and propagate this through an estuary model to provide robust estimates of impacts for the future. River flow data (35-year records at 15-min sampling) were used to characterise variabilities in storm hydrograph shapes and simulate the estuarine response. In particular, we modelled a fast-responding catchment-estuary system (Conwy, UK), where the natural variability in hydrograph shapes generated large variability in estuarine circulation that was not captured when using daily-averaged river forcing. In the extreme, the freshwater plume from a 'flash' flood (lasting <12 h) was underestimated by up to 100% - and the response to nutrient loading was underestimated further still. A model of a slower-responding system (Humber, UK), where hydrographs typically last 2-4 days, showed less variability in estuarine circulation and good approximation with daily-averaged flow forcing. Our result has implications for entire system impact modelling; when we determine future changes to estuaries, some systems will need higher resolution future river flow estimates.

Columbia River Estuary ecosystem classification—Concept and application

USGS Publications Warehouse

Simenstad, Charles A.; Burke, Jennifer L.; O'Connor, Jim E.; Cannon, Charles; Heatwole, Danelle W.; Ramirez, Mary F.; Waite, Ian R.; Counihan, Timothy D.; Jones, Krista L.

2011-01-01

This document describes the concept, organization, and application of a hierarchical ecosystem classification that integrates saline and tidal freshwater reaches of estuaries in order to characterize the ecosystems of large flood plain rivers that are strongly influenced by riverine and estuarine hydrology. We illustrate the classification by applying it to the Columbia River estuary (Oregon-Washington, USA), a system that extends about 233 river kilometers (rkm) inland from the Pacific Ocean. More than three-quarters of this length is tidal freshwater. The Columbia River Estuary Ecosystem Classification ("Classification") is based on six hierarchical levels, progressing from the coarsest, regional scale to the finest, localized scale: (1) Ecosystem Province; (2) Ecoregion; (3) Hydrogeomorphic Reach; (4) Ecosystem Complex; (5) Geomorphic Catena; and (6) Primary Cover Class. We define and map Levels 1-3 for the entire Columbia River estuary with existing geospatial datasets, and provide examples of Levels 4-6 for one hydrogeomorphic reach. In particular, three levels of the Classification capture the scales and categories of ecosystem structure and processes that are most tractable to estuarine research, monitoring, and management. These three levels are the (1) eight hydrogeomorphic reaches that embody the formative geologic and tectonic processes that created the existing estuarine landscape and encompass the influence of the resulting physiography on interactions between fluvial and tidal hydrology and geomorphology across 230 kilometers (km) of estuary, (2) more than 15 ecosystem complexes composed of broad landforms created predominantly by geologic processes during the Holocene, and (3) more than 25 geomorphic catenae embedded within ecosystem complexes that represent distinct geomorphic landforms, structures, ecosystems, and habitats, and components of the estuarine landscape most likely to change over short time periods.

Temporal and Spatial Variation of Water Yield Modulus in the Yangtze River Basin in Recent 60 Years

NASA Astrophysics Data System (ADS)

Shi, Xiaoqing; Weng, Baisha; Qin, Tianling

2018-01-01

The Yangtze River Basin is the largest river basin of Asia and the third largest river basin of the world, the gross water resources amount ranks first in the river basins of the country, and it occupies an important position in the national water resources strategic layout. Under the influence of climate change and human activities, the water cycle has changed. The temporal and spatial distribution of precipitation in the basin is more uneven and the floods are frequent. In order to explore the water yield condition in the Yangtze River Basin, we selected the Water Yield Modulus (WYM) as the evaluation index, then analyzed the temporal and spatial evolution characteristics of the WYM in the Yangtze River Basin by using the climate tendency method and the M-K trend test method. The results showed that the average WYM of the Yangtze River Basin in 1956-2015 are between 103,600 and 1,262,900 m3/km2, with an average value of 562,300 m3/km2, which is greater than the national average value of 295,000 m3/km2. The minimum value appeared in the northwestern part of the Tongtian River district, the maximum value appeared in the northeastern of Dongting Lake district. The rate of change in 1956-2015 is between -0.68/a and 0.79/a, it showed a downward trend in the western part but not significantly, an upward trend in the eastern part reached a significance level of α=0.01. The minimum value appeared in the Tongtian River district, the largest value appeared in the Hangjia Lake district, and the average tendency rate is 0.04/a in the whole basin.

Large wood in the Snowy River estuary, Australia

NASA Astrophysics Data System (ADS)

Hinwood, Jon B.; McLean, Errol J.

2017-02-01

In this paper we report on 8 years of data collection and interpretation of large wood in the Snowy River estuary in southeastern Australia, providing quantitative data on the amount, sources, transport, decay, and geomorphic actions. No prior census data for an estuary is known to the authors despite their environmental and economic importance and the significant differences between a fluvial channel and an estuarine channel. Southeastern Australian estuaries contain a significant quantity of large wood that is derived from many sources, including river flood flows, local bank erosion, and anthropogenic sources. Wind and tide are shown to be as important as river flow in transporting and stranding large wood. Tidal action facilitates trapping of large wood on intertidal bars and shoals; but channels are wider and generally deeper, so log jams are less likely than in rivers. Estuarine large wood contributes to localised scour and accretion and hence to the modification of estuarine habitat, but in the study area it did not have large-scale impacts on the hydraulic gradients nor the geomorphology.

Subtidal sea level variability in a shallow Mississippi River deltaic estuary, Louisiana

USGS Publications Warehouse

Snedden, G.A.; Cable, J.E.; Wiseman, W.J.

2007-01-01

The relative roles of river, atmospheric, and tidal forcings on estuarine sea level variability are examined in Breton Sound, a shallow (0.7 m) deltaic estuary situated in an interdistributary basin on the Mississippi River deltaic plain. The deltaic landscape contains vegetated marshes, tidal flats, circuitous channels, and other features that frictionally dissipate waves propagating through the system. Direct forcing by local wind stress over the surface of the estuary is minimal, owing to the lack of significant fetch due to landscape features of the estuary. Atmospheric forcing occurs almost entirely through remote forcing, where alongshore winds facilitate estuary-shelf exchange through coastal Ekman convergence. The highly frictional nature of the deltaic landscape causes the estuary to act as a low-pass filter to remote atmospheric forcing, where high-frequency, coastally-induced fluctuations are significantly damped, and the damping increases with distance from the estuary mouth. During spring, when substantial quantities of controlled Mississippi River inputs (q?? = 62 m3 s-1) are discharged into the estuary, upper estuary subtidal sea levels are forced by a combination of river and remote atmospheric forcings, while river effects are less clear downestuary. During autumn (q?? = 7 m3 s-1) sea level variability throughout the estuary is governed entirely by coastal variations at the marine boundary. A frequency-dependent analytical model, previously used to describe sea level dynamics forced by local wind stress and coastal forcing in deeper, less frictional systems, is applied in the shallow Breton Sound estuary. In contrast to deeper systems where coastally-induced fluctuations exhibit little or no frictional attenuation inside the estuary, these fluctuations in the shallow Breton Sound estuary show strong frequency-dependent amplitude reductions that extend well into the subtidal frequency spectrum. ?? 2007 Estuarine Research Federation.

Vertical dissolved inorganic nitrogen fluxes in marsh and mudflat areas of the yangtze estuary.

PubMed

Deng, Huanguang; Wang, Dongqi; Chen, Zhenlou; Liu, Jie; Xu, Shiyuan; White, John R

2014-03-01

Nitrogen (N) is a dominant macronutrient in many river-dominated coastal systems, and excess concentrations can drive eutrophication, the effects of which can include hypoxia and algal blooms. The Yangtze River in China transports a large amount of dissolved inorganic N. Therefore, it is important to understand the role of the marsh and mudflat areas within the estuary on processing this exogenous N load. In situ dissolved inorganic nitrogen (DIN) fluxes across the sediment-water interface were determined monthly at Chongming Island at two sites (a vegetated marsh and an unvegetated mudflat) and were compared with rates from a previously published laboratory incubation study by our research group. Results from the in situ study showed that NO flux rates comprised the major component of total DIN flux, ranging from 55 to 97%. No significant difference was observed in the N flux rates between the marsh and mudflat sites. Overall, sediment at both sites served as a sink of DIN from surface water with mean flux rates of -178 μmol m h and -165 μmol m h for the marsh and mudflat, respectively. In general, DIN flux rates were not significantly correlated with DIN concentrations and other measured parameters (temperature, dissolved oxygen, salinity, and pH) of surface water. The in situ measured fluxes of NO and NO in this study were not significantly different from those of our previous laboratory incubation ( > 0.05), whereas NH fluxes in situ were significantly lower than those from the laboratory core incubations ( < 0.05). This result suggests that caution should be used when extrapolating rates from laboratory incubation methods to the field because the rates might not be equivalent. Copyright © by the American Society of Agronomy, Crop Science Society of America, and Soil Science Society of America, Inc.

Biocides in the Yangtze River of China: spatiotemporal distribution, mass load and risk assessment.

PubMed

Liu, Wang-Rong; Zhao, Jian-Liang; Liu, You-Sheng; Chen, Zhi-Feng; Yang, Yuan-Yuan; Zhang, Qian-Qian; Ying, Guang-Guo

2015-05-01

Nineteen biocides were investigated in the Yangtze River to understand their spatiotemporal distribution, mass loads and ecological risks. Fourteen biocides were detected, with the highest concentrations up to 166 ng/L for DEET in surface water, and 54.3 ng/g dry weight (dw) for triclocarban in sediment. The dominant biocides were DEET and methylparaben, with their detection frequencies of 100% in both phases. An estimate of 152 t/y of 14 biocides was carried by the Yangtze River to the East China Sea. The distribution of biocides in the aquatic environments was significantly correlated to Gross Domestic Product (GDP), total phosphorus (TP) and total nitrogen (TN), suggesting dominant input sources from domestic wastewater of the cities along the river. Risk assessment showed high ecological risks posed by carbendazim in both phases and by triclosan in sediment. Therefore, proper measures should be taken to reduce the input of biocides into the river systems. Copyright © 2015 Elsevier Ltd. All rights reserved.

Spatiotemporal distribution and mass loadings of perfluoroalkyl substances in the Yangtze River of China.

PubMed

Pan, Chang-Gui; Ying, Guang-Guo; Zhao, Jian-Liang; Liu, You-Sheng; Jiang, Yu-Xia; Zhang, Qian-Qian

2014-09-15

A systematic investigation into contamination profiles of eighteen perfluoroalkyl substances (PFASs) in both surface water and sediments of Yangtze River was carried out by using high performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS) in summer and winter of 2013. The total concentrations of the PFASs in the water and sediment of Yangtze River ranged from 2.2 to 74.56 ng/L and 0.05 to 1.44 ng/g dry weights (dw), respectively. The PFAS concentrations were correlated to some selected water quality parameters such as pH, total phosphorus (TP), total nitrogen (TN) and conductivity in water, and some sediment properties, such as total organic carbon (TOC), TP, and TN in sediment. The monitoring results for the water and sediment samples showed no obvious seasonal variations. Among the selected 18 PFASs, perfluorooctanoic acid (PFOA) was the dominant PFAS compound found both in water and sediment for the two seasons with its maximum concentration of 18.03 ng/L in water and 0.72 ng/g in sediment, followed by perfluorobutane sulfonic acid (PFBS) with its maximum concentration of 41.9 ng/L in water in Wuhan, whereas the lowest concentrations of PFASs were observed at Poyang lake. The annual loadings of PFOA, perfluorohexanoic acid (PFHxA), PFBS, perfluorooctane sulfonic acid (PFOS) and the total PFASs in the Yangtze River were 6.8 tons, 2.2 tons, 8.2 tons, 0.88 tons, and 20.7 tons, respectively. Wuhan and Er'zhou of Hubei contributed the most amounts of PFASs into the Yangtze River. A correlation was found between some PFASs, for example PFBS and PFOS, which suggests that both of these PFASs originate from common sources in the region. Copyright © 2014 Elsevier B.V. All rights reserved.

Channel morphology and its impact on flood passage, the Tianjiazhen reach of the middle Yangtze River

NASA Astrophysics Data System (ADS)

Shi, Yafeng; Zhang, Qiang; Chen, Zhongyuan; Jiang, Tong; Wu, Jinglu

2007-03-01

The Tianjiazhen reach of the middle Yangtze is about 8 km long, and characterized by a narrow river width of 650 m and local water depth of > 90 m in deep inner troughs, of which about 60 m is below the mean sea level. The troughs in the channel of such a large river are associated with regional tectonics and local lithology. The channel configuration plays a critical role in modifying the height and duration of river floods and erosion of the riverbed. The formation of the troughs in the bed of the Yangtze is considered to be controlled by sets of NW-SE-oriented neotectonic fault zones, in which some segments consist of highly folded thick Triassic limestone crossed by the Yangtze River. Several limestone hills, currently located next to the river channel, serve as nodes that create large vortices in the river, thereby accelerating downcutting on the riverbed composed of limestone highly susceptible to physical corrosion and chemical dissolution. Hydrological records indicate that the nodal hills and channel configuration at Tianjiazhen do not impact on normal flow discharges but discharges > 50,000 m 3s - 1 are slowed down for 2-3 days. Catastrophic floods are held up for even longer periods. These inevitably result in elevated flood stages upstream of prolonged duration, affecting large cities such as Wuhan and a very large number of people.

[Study on distribution and countermeasures of Oncomelania snails in beach wetlands of Runzhou section of lower reaches of Yangtze River].

PubMed

Xia, Ai; Huang, Yixin; Jiang, Jun; Zhou, Ya-Min; Hang, De-rong; Tao, Heng-ye

2014-04-01

To understand the distribution of the river beach wetlands and Oncomelania snails in the lower reaches of the Yangtze River, and explore the countermeasures of snail control. The river beach wetlands outside the Yangtze River levee were investigated and classified according to the hierarchical and classification system of wetlands of China. The snail survey was carried out in the beach wetlands of Runzhou section of lower reaches of the Yangtze River from 2004 to 2013. The change trend of snail areas and the densities was analyzed in the wetlands. The river beach of Runzhou section of lower reaches of the Yangtze River belongs to the riverine wetland. There was Oncomelania snail breeding except the permanent water area. At present, there were natural wetlands of 1303.0 hm2, human-made wetlands of 1479.0 hmb2 and wetland function changes of 1059.0 hm2 in the river beach of Runzhou section. There was the snail area of 181.4 hm2 in the natural wetland in 2013. The area of snail control by the molluscicide and environmental modification was 4624.55 hm2 from 2004 to 2013. The decline rates of snail areas and densities were 66.53% and 77.66% respectively. The existing Oncomelania snails were distributed in the natural wetlands. The human-made wetland is helpful to snail control. The snail control in the river beach wetlands should attach a great importance to the protection of wetland ecology.

Fractionation of rare earth elements in the Mississippi River estuary and river sediments

NASA Astrophysics Data System (ADS)

Adebayo, S. B.; Johannesson, K. H.

2017-12-01

This study presents the first set of data on the fractionation of rare earth elements (REE) in the mixing zone between the Mississippi River and the Gulf of Mexico, as well as the fractionation of REE in the operationally defined fractions of Mississippi River sediments. This subject is particularly important because the Mississippi river is one of the world's major rivers, and contributes a substantial amount of water and sediment to the ocean. Hence, it is a major source of trace elements to the oceans. The geochemistry of the REE in natural systems is principally important because of their unique chemical properties, which prompt their application as tracers of mass transportation in modern and paleo-ocean environments. Another important consideration is the growth in the demand and utilization of REE in the green energy and technology industries, which has the potential to bring about a change in the background levels of these trace elements in the environment. The results of this study show a heavy REE enrichment of both the Mississippi River water and the more saline waters of the mixing zone. Our data demonstrate that coagulation and removal of REE in the low salinity region of the estuary is more pronounced among the Light REE ( 35% for Nd) compared to the Heavy REE. Remarkably, our data also indicate that REE removal in the Mississippi River estuary is significantly less than that observed in other estuaries, including the Amazon River system. We propose that the high pH/alkalinity of the Mississippi River is responsible for the greater stability of REE in the Mississippi River estuary. The results of sequential extraction of river sediments reveal different Sm/Nd ratios for the various fractions, which we submit implies different 143Nd/144Nd ratios of the labile fractions of the sediments. The possible impact of such hypothesized different Nd isotope signatures of labile fractions of the river sediments on Gulf of Mexico seawater is under investigation.

Risk and toxicity assessments of heavy metals in sediments and fishes from the Yangtze River and Taihu Lake, China.

PubMed

Fu, Jie; Hu, Xin; Tao, Xiancong; Yu, Hongxia; Zhang, Xiaowei

2013-11-01

Heavy metal pollution is one of the most serous environmental issues globally. To evaluate the metal pollution in Jiangsu Province of China, the total concentrations of heavy metals in sediments and fishes from the Yangtze River and Taihu Lake were analyzed. Ecological risk of sediments and human health risk of fish consumption were assessed respectively. Furthermore, toxicity of samples on expression of the stress responsive genes was evaluated using microbial live cell-array method. The results showed that the heavy metals concentrations in sediments from the Yangtze River were much higher than those in sediments from the Taihu Lake. However, the fishes from the Taihu Lake had higher concentrations of heavy metals than fishes from the Yangtze River. Ecological risk evaluation showed that the heavy metal contaminants in sediments from the Yangtze River posed higher risk of adverse ecological effects, while sediments from the study areas of Taihu Lake were relatively safe. Health risk assessment suggested that the heavy metals in fishes of both Yangtze River and Taihu Lake might have risk of adverse health effects to human. The toxicity assessment indicated that the heavy metals in these sediments and fishes showed transcriptional effects on the selected 21 stress responsive genes, which were involved in the pathways of DNA damage response, chemical stress, and perturbations of electron transport. Together, this field investigation combined with chemical analysis, risk assessment and toxicity bioassay would provide useful information on the heavy metal pollution in Jiangsu Province. Copyright © 2013 Elsevier Ltd. All rights reserved.

Discontinuous Galerkin modeling of the Columbia River's coupled estuary-plume dynamics

NASA Astrophysics Data System (ADS)

Vallaeys, Valentin; Kärnä, Tuomas; Delandmeter, Philippe; Lambrechts, Jonathan; Baptista, António M.; Deleersnijder, Eric; Hanert, Emmanuel

2018-04-01

The Columbia River (CR) estuary is characterized by high river discharge and strong tides that generate high velocity flows and sharp density gradients. Its dynamics strongly affects the coastal ocean circulation. Tidal straining in turn modulates the stratification in the estuary. Simulating the hydrodynamics of the CR estuary and plume therefore requires a multi-scale model as both shelf and estuarine circulations are coupled. Such a model has to keep numerical dissipation as low as possible in order to correctly represent the plume propagation and the salinity intrusion in the estuary. Here, we show that the 3D baroclinic discontinuous Galerkin finite element model SLIM 3D is able to reproduce the main features of the CR estuary-to-ocean continuum. We introduce new vertical discretization and mode splitting that allow us to model a region characterized by complex bathymetry and sharp density and velocity gradients. Our model takes into account the major forcings, i.e. tides, surface wind stress and river discharge, on a single multi-scale grid. The simulation period covers the end of spring-early summer of 2006, a period of high river flow and strong changes in the wind regime. SLIM 3D is validated with in-situ data on the shelf and at multiple locations in the estuary and compared with an operational implementation of SELFE. The model skill in the estuary and on the shelf indicate that SLIM 3D is able to reproduce the key processes driving the river plume dynamics, such as the occurrence of bidirectional plumes or reversals of the inner shelf coastal currents.

[Prevalence of hypertension and its influencing factors in rural areas along the Yangtze River in Anhui Province in 2014-2015].

PubMed

Hu, Mingjun; Zhou, Mengmeng; Yang, Yuwei; Liang, Ling; Zhong, Qi; Qin, Qirong; Wang, Xiaodong; Huang, Fen

2017-11-01

To investigate the prevalence, awareness, treatment, control and related influence factors of hypertension among rural adult residents in areas along the Yangtze River in Anhui Province. Totally 2873 rural adult residents in seven typical towns along the Yangtze River of Chizhou, Tongling and Ma'anshan Cities, Anhui Province were selected, with multistage-stratified random cluster sampling, to perform questionnaires and physical measurements from year 2014 to 2015. The prevalence of hypertension was 30. 7%( standardized prevalence was 18. 4%), the awareness rate was 50. 6%( standardized rate was 29. 0%), the treatment rate was40. 4%( standardized rate was 18. 7%), the control rate was 17. 7%( standardized ratewas 9. 3%) in rural areas along the Yangtze River in Anhui Province. The prevalence, awareness, treatment and control rates of hypertension were increased with age increase. Abdominal obesity( OR = 1. 855, 95% CI 1. 467-2. 344), family history of hypertension( OR = 1. 594, 95% CI 1. 265-2. 008), the average annual household income < 60 000 yuan and increased BMI were risk factors of hypertension in rural areas along the Yangtze River. Female( OR = 0. 734, 95% CI 0. 604-0. 891) was its protective factors. While the factors of awareness, treatment and control rates of hypertension were not same. The prevalence of hypertension is higher in the areas along the Yangtze River in Anhui Province. However, the awareness, treatment and control rate of hypertension are lower.

The range expansion patterns of Spartina alterniflora on salt marshes in the Yangtze Estuary, China

NASA Astrophysics Data System (ADS)

Xiao, Derong; Zhang, Liquan; Zhu, Zhenchang

2010-06-01

The range expansion patterns of Spartina alterniflora and the roles which sexual reproduction and asexual propagation play in range expansion were investigated at the Chongming Dongtan nature reserve in the Yangtze Estuary, China. Two range expansion patterns of S. alterniflora at its advancing fronts could be found (1) S. alterniflora-mudflat front (S-M) and (2) S. alterniflora- Scirpus mariqueter-mudflat front (S-S-M). One feature revealed by this study was that a flush of seedling recruitment and establishment in spring was a crucial way for S. alterniflora to colonize new habitats and achieve a fast rate of range expansion. The mean number of seedlings recruited at the S-M front was much higher than that at the S-S-M front. Once established, the survivorship of seedlings was high, both at the S-M and S-S-M fronts. The established seedlings formed new tussocks quickly by vegetative tillering and growth of rhizomes and these finally merged into dense meadows. The mean distance of range expansion of S. alterniflora, after one growing season at the S-M front, was 25.4 ± 3.1 m yr -1 and 2.7 ± 0.5 m yr -1 at the S-S-M front. Sexual reproduction by seedlings and asexual propagation by tillering and growth of rhizomes were the two main means by which S. alterniflora could maintain a fast rate of range expansion on the salt marshes of the Yangtze Estuary. The colonization behaviors of S. alterniflora on advancing fronts differed as a reaction to various external and internal factors. The impact of abiotic and biotic factors governing the range expansion of S. alterniflora and its implications for the spatial structure of tidal wetlands are discussed.

Impact of climate change on the streamflow hydrology of the Yangtze River in China

USDA-ARS?s Scientific Manuscript database

Tuotuo River basin, the source region of the Yangtze River, is the key area, where the impact of climate change has been observed on many of the hydrological processes of this central region of the Tibetan Plateau. In this study, we examined six global climate models (GCMs) under three Respectively ...

DNA barcoding and evaluation of genetic diversity in Cyprinidae fish in the midstream of the Yangtze River.

PubMed

Shen, Yanjun; Guan, Lihong; Wang, Dengqiang; Gan, Xiaoni

2016-05-01

The Yangtze River is the longest river in China and is divided into upstream and mid-downstream regions by the Three Gorges (the natural barriers of the Yangtze River), resulting in a complex distribution of fish. Dramatic changes to habitat environments may ultimately threaten fish survival; thus, it is necessary to evaluate the genetic diversity and propose protective measures. Species identification is the most significant task in many fields of biological research and in conservation efforts. DNA barcoding, which constitutes the analysis of a short fragment of the mitochondrial cytochrome c oxidase subunit I (COI) sequence, has been widely used for species identification. In this study, we collected 561 COI barcode sequences from 35 fish from the midstream of the Yangtze River. The intraspecific distances of all species were below 2% (with the exception of Acheilognathus macropterus and Hemibarbus maculatus). Nevertheless, all species could be unambiguously identified from the trees, barcoding gaps and taxonomic resolution ratio values. Furthermore, the COI barcode diversity was found to be low (≤0.5%), with the exception of H. maculatus (0.87%), A. macropterus (2.02%) and Saurogobio dabryi (0.82%). No or few shared haplotypes were detected between the upstream and downstream populations for ten species with overall nucleotide diversities greater than 0.00%, which indicated the likelihood of significant population genetic structuring. Our analyses indicated that DNA barcoding is an effective tool for the identification of cyprinidae fish in the midstream of the Yangtze River. It is vital that some protective measures be taken immediately because of the low COI barcode diversity.

Remote sensing of cloud distributions over the Bayanhar Mountains - Watershed of the Yangtze and Yellow rivers

NASA Technical Reports Server (NTRS)

Hung, R. J.; Liu, J. M.; Dodge, J. C.; Smith, R. E.

1986-01-01

Although the two largest rivers in China originate in the same region separated only by the Bayanhar Mountains as a watershed, the Yangtze and Yellow rivers behave in quite different ways. Most of the warm and humid air currents from the Arabian sea and the Bay of Bengal are blocked by the Bayanhar Mountains. As a result the amount of water in the Yellow River is only 5 percent of that in the Yangtze river. Based on the cloud coverage area and the cloud volumetric distributions, and also the thickness above 9.4 km of the cumulus clouds located north and south of the Bayanhar Mountains from the geosynchronous satellite infrared imagery, the results suggest that a more detailed investigation is warranted in the hope that the proper modification of cumuli north of the Bayanhar Mountains would enhance the rainfall over the fountainhead of the Yellow River.

Morphology and mechanism of the very large dunes in the tidal reach of the Yangtze River, China

NASA Astrophysics Data System (ADS)

Shuwei, Zheng; Heqin, Cheng; Shuaihu, Wu; Shengyu, Shi; Wei, Xu; Quanping, Zhou; Yuehua, Jiang

2017-05-01

High-resolution multibeam data was used to interpret the surface morphology of very large dunes (VLDs) in the tidal reach of the Yangtze River, China. These VLDs can be divided into three categories according to their surface morphological characteristics. (1) VLDs-I: those with a smooth surface and cross-section; (2) VLDs-II: those accompanied by secondary dunes; (3) VLDs-III: those accompanied by secondary dunes and numerous elliptical pits. Parameters and spatial distribution of VLDs, and bed surface sediment were analyzed in the laboratory. Overall, channel morphology is an important factor affecting the development of VLDs, and channels with narrow and straight and certain water surface slope are facilitating the development of VLDs by constraining stream power. Meanwhile, distribution density of VLDs depicts a decreasing trend from Chizhou towards the estuary, are probably influenced by channel morphology and width. Associated pits in VLDs-III change the 3D dune morphology by distributing in secondary dunes as beads. The Three Gorges Dam project (TGP) leads to the bed surface sediment activity frequently and leads to the riverbed surface sediment coarsens, which promotes the further development of dunes. Moreover, other human activities, such as river regulation project, sand mining and Deep Water Channel Regulation Project have changed the regional river boundary conditions and hydrodynamic conditions are influential on the development of VLDs.

Mutagenicity and estrogenicity of raw water and drinking water in an industrialized city in the Yangtze River Delta.

PubMed

Xiao, Sanhua; Lv, Xuemin; Zeng, Yifan; Jin, Tao; Luo, Lan; Zhang, Binbin; Zhang, Gang; Wang, Yanhui; Feng, Lin; Zhu, Yuan; Tang, Fei

2017-10-01

Public concern was aroused by frequently reported water pollution incidents in Taihu Lake and the Yangtze River. The pollution also caught and sustained the attention of the scientific community. From 2010 to 2016, raw water and drinking water samples were continually collected at Waterworks A and B (Taihu Lake) and Waterworks C (Yangtze River). The non-volatile organic pollutants in the water samples were extracted by solid phase extraction. Ames tests and yeast estrogen screen (YES) assays were conducted to evaluate the respective mutagenic and estrogenic effects. Water samples from the Yangtze River-based Waterworks C possessed higher mutagenicity than those from Taihu Lake-based Waterworks A (P＜0.001) and Waterworks B (P = 0.026). Water treatment enhanced the direct mutagenicity (P = 0.022), and weakened the estrogenicity of the raw water (P＜0.001) with a median removal rate of 100%. In fact, very few of the finished samples showed estrogenic activity. Raw water samples from Waterworks A showed weaker estrogenicity than those from Waterworks B (P = 0.034) and Waterworks C (P = 0.006). In summary, mutagenic effects in drinking water and estrogenic effects in raw water merited sustained attention. The Yangtze River was more seriously polluted by mutagenic and estrogenic chemicals than Taihu Lake was. Copyright © 2017 Elsevier Ltd. All rights reserved.

Concentrations, loads, and sources of polychlorinated biphenyls, Neponset River and Neponset River Estuary, eastern Massachusetts

USGS Publications Warehouse

Breault, Robert F.

2011-01-01

Polychlorinated biphenyls (PCBs) are known to contaminate the Neponset River, which flows through parts of Boston, Massachusetts, and empties into the Neponset River Estuary, an important fish-spawning area. The river is dammed and impassable to fish. The U.S. Geological Survey, in cooperation with the Massachusetts Department of Fish and Game, Division of Ecological Restoration, Riverways Program, collected, analyzed, and interpreted PCB data from bottom-sediment, water, and (or) fish-tissue samples in 2002, 2004-2006. Samples from the Neponset River and Neponset River Estuary were analyzed for 209 PCB congeners, PCB homologs, and Aroclors. In order to better assess the overall health quality of river-bottom sediments, sediment samples were also tested for concentrations of 31 elements. PCB concentrations measured in the top layers of bottom sediment ranged from 28 nanograms per gram (ng/g) just upstream of the Mother Brook confluence to 24,900 ng/g measured in Mother Brook. Concentrations of elements in bottom sediment were generally higher than background concentrations and higher than levels considered toxic to benthic organisms according to freshwater sediment-quality guidelines defined by the U.S. Environmental Protection Agency. Concentrations of dissolved PCBs in water samples collected from the Neponset River (May 13, 2005 to April 28, 2006) averaged about 9.2 nanograms per liter (ng/L) (annual average of monthly values); however, during the months of August (about 16.5 ng/L) and September (about 15.6 ng/L), dissolved PCB concentrations were greater than 14 ng/L, the U.S. Environmental Protection Agency's freshwater continuous chronic criterion for aquatic organisms. Concentrations of PCBs in white sucker (fillets and whole fish) were all greater than 2,000 ng/g wet wt, the U.S. Environmental Protection Agency's guideline for safe consumption of fish: PCB concentrations measured in fish-tissue samples collected from the Tileston and Hollingsworth and

[Characteristics of ichthyoplankton assemblages in Yangtze Estuary and adjacent waters in spring].

PubMed

Liu, Shu-De; Xian, Wei-Wei; Liu, Dong

2008-10-01

Based on the investigation data of ichthyoplankton assemblages and environmental factors in Yangtze Estuary and adjacent waters in May 1999 and 2001, the characteristics of ichthyoplankton assemblages in these areas in spring were studied by using TWINSPAN (two-way indicator species analysis) and CCA (canonical correspondence analysis). A total of 11 540 ichthyoplankton individuals were taxonomically identified, belonging to 11 orders, 18 families and 32 species, of which, Coilia mystus, Engraulis japonicus, Chaeturichthys hexanema, Allanetta bleekeri, and Trachidermis fasciatus were the dominant species. The ichthyoplankton communities were classified into three assemblages by using TWINSPAN, i.e., estuarine assemblage dominated by C. mystus, coastal assemblage dominated by A. bleekeri and T. fasciatus; and shelf assemblage featured by E. japonicus and C. hexanema. The CCA ordination of the interrelations among the three assemblages and their correlations to the environmental variables revealed that salinity, depth, dissolved oxygen, and total suspended particulate matter were the major factors affecting the ichthyoplankton assemblages in the study areas.

Nutrient input through submarine groundwater discharge in two major Chinese estuaries: the Pearl River Estuary and the Changjiang River Estuary

NASA Astrophysics Data System (ADS)

Liu, Jianan; Du, Jinzhou; Wu, Ying; Liu, Sumei

2018-04-01

In this study, we used a 224Ra mass balance model to evaluate the importance of submarine groundwater discharge (SGD) for the budgets of biogenic elements in two major Chinese estuaries: the Pearl River Estuary (PRE) and the Changjiang River Estuary (CRE). The apparent water age in the PRE was estimated to be 4.8 ± 1.1 days in the dry season and 1.8 ± 0.6 days in the wet season using a physical model based on the tidal prism. In the dry season, the water age in the CRE was estimated to be 11.7 ± 3.0 days using the 224Ra/223Ra activities ratios apparent age model. By applying the 224Ra mass balance model, we obtained calculations of the SGD flow in the PRE of (4.5-10) × 108 m3 d-1 (0.23-0.50 m3 m-2 d-1) and (1.2-2.7) × 108 m3 d-1 (0.06-0.14 m3 m-2 d-1) in the dry season and wet season, respectively, and the estimated SGD flux was (4.6-11) × 109 m3 d-1 (0.18-0.45 m3 m-2 d-1) in the dry season of the CRE. In comparison with the nutrient fluxes from the rivers, the SGD-derived nutrient fluxes may play a vital role in controlling the nutrient budgets and stoichiometry in the study areas. The large amount of dissolved inorganic nitrogen and phosphorus fluxes together with high N: P ratios into the PRE and CRE would potentially contribute to eutrophication and the occurrence of red tides along the adjacent waters.

AN ECOSYSTEM MODEL OF A RIVER-DOMINATED PACIFIC NORTHWEST ESTUARY: ROLES OF SALT MARSH-, RIVER- AND OCEAN-DERIVED MATERIALS

EPA Science Inventory

The Salmon River estuary on the central Oregon coast is river-dominated, with hydraulic residence times ranging from <1 day during winter high flows to a week during low flows. The estuary receives organic matter and nutrients from the river, the coastal ocean, and a bordering s...

Winter nutrient behaviours in the Pearl River estuary

NASA Astrophysics Data System (ADS)

Wang, G.; Jin, S.; Du, M.

2017-12-01

Nutrient (nitrate, nitrite, ammonium, phosphate, and silicate) mapping and time-series investigation were carried out in winter in the Pearl River estuary, China. These nutrients behaved non-conservatively in the upper estuary. In the middle and lower estuary, however, nitrate and silicate seemed to be controled by physical mixing, while additions of nitrite, ammonium, and phosphate were found in the middle estuary. Nitrate was the dominant disslved inorganic nitrogen, with a fraction of more than 2/3. From the upper to the lower estuary the N:P ratio decreased from more than 200 to near the Redfield ratio of 16. Nutrients near the surface behaved almost the same as near the bottom in the water column at both the uppper and lower estuary. During a tidal cycle these nutrients seemed to be regulated more by physical mixing than by other processes.

Predictability of current and future multi-river discharges: Ganges, Brahmaputra, Yangtze, Blue Nile, and Murray-Darling rivers

NASA Astrophysics Data System (ADS)

Jian, Jun

2007-12-01

Determining river discharge is of critical importance to many societies as they struggle with fresh water supply and risk of flooding. In Bangladesh, floods occur almost every year but with sufficient irregularity to have adverse social and economical consequences. Important goals are to predict the discharge to be used for the optimization of agricultural practices, disaster mitigation and water resource management. The aim of this study is to determine the predictability of river discharge in a number of major rivers on time scale varying from weeks to a century. We investigated predictability considering relationship between SST and discharge. Next, we consider IPCC model projections of river discharge while the models are statistically adjusted against observed discharges. In this study, we consider five rivers, the Ganges, the Brahmaputra, the Yangtze, the Blue Nile, and the Murray-Darling Rivers. On seasonal time scales, statistically significant correlations are found between mean monthly equatorial Pacific sea surface temperature (SST) and the summer Ganges discharge with lead times of 2-3 months due to oscillations of the El Nino-Southern Oscillation (ENSO) phenomena. In addition, there are strong correlations in the southwest and northeast Pacific. These, too, appear to be tied to the ENSO cycle. The Brahmaputra discharge, on the other hand, shows somewhat weaker relationships with tropical SST. Strong lagged correlations relationships are found with SST in the Bay of Bengal but these are the result of very warm SSTs and exceptional Brahmaputra discharge during the summer of 1998. When this year is removed from the time series, relationships weaken everywhere except in the northwestern Pacific for the June discharge and in areas of the central Pacific straddling the equator for the July discharge. The relationships are relative strong, but they are persistent from month to month and suggest that two different and sequential factors influence Brahmaputra

Yangtze River, an insignificant genetic boundary in tufted deer (Elaphodus cephalophus): the evidence from a first population genetics study.

PubMed

Sun, Zhonglou; Pan, Tao; Wang, Hui; Pang, Mujia; Zhang, Baowei

2016-01-01

Great rivers were generally looked at as the geographical barrier to gene flow for many taxonomic groups. The Yangtze River is the third largest river in the world, and flows across South China and into the East China Sea. Up until now, few studies have been carried out to evaluate its effect as a geographical barrier. In this study, we attempted to determine the barrier effect of the Yangtze River on the tufted deer ( Elaphodus cephalophus ) using the molecular ecology approach. Using mitochondrial DNA control region (CR) sequences and 13 nuclear microsatellite loci, we explored the genetic structure and gene flow in two adjacent tufted deer populations (Dabashan and Wulingshan populations), which are separated by the Yangtze River. Results indicated that there are high genetic diversity levels in the two populations, but no distinguishable haplotype group or potential genetic cluster was detected which corresponded to specific geographical population. At the same time, high gene flow was observed between Wulingshan and Dabashan populations. The tufted deer populations experienced population decrease from 0.3 to 0.09 Ma BP, then followed by a distinct population increase. A strong signal of recent population decline ( T = 4,396 years) was detected in the Wulingshan population by a Markov-Switching Vector Autoregressions(MSVAR) process population demography analysis. The results indicated that the Yangtze River may not act as an effective barrier to gene flow in the tufted deer. Finally, we surmised that the population demography of the tufted deer was likely affected by Pleistocene climate fluctuations and ancient human activities.

Variations of Runoff and Sediment Load in the Middle and Lower Reaches of the Yangtze River, China (1950-2013)

PubMed Central

Li, Na; Wang, Lachun; Zeng, Chunfen; Wang, Dong; Liu, Dengfeng; Wu, Xutong

2016-01-01

On the basis of monthly runoff series obtained in 1950–2013 and annual sediment load measured in 1956–-2013 at five key hydrological stations in the middle and lower reaches of the Yangtze River basin, this study used the Mann-Kendall methods to identify trend and abrupt changes of runoff and sediment load in relation to human activities. The results were as follows: (1) The annual and flood season runoffs showed significant decreasing trends at Yichang station, and showed slight downward trends at Hankou and Datong stations, while the abrupt changes of dry season runoff at Yichang, Hankou and Datong stations occurred in about 2007 and the change points were followed by significant increasing trends. The construction of the Three Gorges Dam, which began to operate in 2003, influenced the variations of runoff in the mainstream of Yangtze River, but the effect weakened with the distance along the downstream direction from TGD. (2) Since the 1990s, annual sediment loads at Yichang, Hankou, and Datong stations have been decreasing significantly, and after 2002, the annual sediment load at Yichang dropped below that of Hankou and Datong. The dams and deforestation/forestation contributed to the significant decreasing trend of the sediment load. In addition, the Three Gorges Dam aggravated the downward trend and caused the erosion of the riverbed and riverbanks in the middle and lower reaches. (3) The runoff and sediment load flowing from Dongting Lake into the mainstream of the Yangtze River showed significant decreasing trends at Chenglingji station after 1970s, and in contrast, slight increase in the sediment flow from Poyang Lake to the mainstream of the Yangtze River at Hukou station were detected over the post-TGD period (2003–2013). The result of the study will be an important foundation for watershed sustainable development of the Yangtze River under the human activities. PMID:27479591

Variations of Runoff and Sediment Load in the Middle and Lower Reaches of the Yangtze River, China (1950-2013).

PubMed

Li, Na; Wang, Lachun; Zeng, Chunfen; Wang, Dong; Liu, Dengfeng; Wu, Xutong

2016-01-01

On the basis of monthly runoff series obtained in 1950-2013 and annual sediment load measured in 1956--2013 at five key hydrological stations in the middle and lower reaches of the Yangtze River basin, this study used the Mann-Kendall methods to identify trend and abrupt changes of runoff and sediment load in relation to human activities. The results were as follows: (1) The annual and flood season runoffs showed significant decreasing trends at Yichang station, and showed slight downward trends at Hankou and Datong stations, while the abrupt changes of dry season runoff at Yichang, Hankou and Datong stations occurred in about 2007 and the change points were followed by significant increasing trends. The construction of the Three Gorges Dam, which began to operate in 2003, influenced the variations of runoff in the mainstream of Yangtze River, but the effect weakened with the distance along the downstream direction from TGD. (2) Since the 1990s, annual sediment loads at Yichang, Hankou, and Datong stations have been decreasing significantly, and after 2002, the annual sediment load at Yichang dropped below that of Hankou and Datong. The dams and deforestation/forestation contributed to the significant decreasing trend of the sediment load. In addition, the Three Gorges Dam aggravated the downward trend and caused the erosion of the riverbed and riverbanks in the middle and lower reaches. (3) The runoff and sediment load flowing from Dongting Lake into the mainstream of the Yangtze River showed significant decreasing trends at Chenglingji station after 1970s, and in contrast, slight increase in the sediment flow from Poyang Lake to the mainstream of the Yangtze River at Hukou station were detected over the post-TGD period (2003-2013). The result of the study will be an important foundation for watershed sustainable development of the Yangtze River under the human activities.

Attribution of extreme precipitation in the lower reaches of the Yangtze River during May 2016

NASA Astrophysics Data System (ADS)

Li, Chunxiang; Tian, Qinhua; Yu, Rong; Zhou, Baiquan; Xia, Jiangjiang; Burke, Claire; Dong, Buwen; Tett, Simon F. B.; Freychet, Nicolas; Lott, Fraser; Ciavarella, Andrew

2018-01-01

May 2016 was the third wettest May on record since 1961 over central eastern China based on station observations, with total monthly rainfall 40% more than the climatological mean for 1961-2013. Accompanying disasters such as waterlogging, landslides and debris flow struck part of the lower reaches of the Yangtze River. Causal influence of anthropogenic forcings on this event is investigated using the newly updated Met Office Hadley Centre system for attribution of extreme weather and climate events. Results indicate that there is a significant increase in May 2016 rainfall in model simulations relative to the climatological period, but this increase is largely attributable to natural variability. El Niño years have been found to be correlated with extreme rainfall in the Yangtze River region in previous studies—the strong El Niño of 2015-2016 may account for the extreme precipitation event in 2016. However, on smaller spatial scales we find that anthropogenic forcing has likely played a role in increasing the risk of extreme rainfall to the north of the Yangtze and decreasing it to the south.

Terrestrial Contributions to the Aquatic Food Web in the Middle Yangtze River

PubMed Central

Wang, Jianzhu; Gu, Binhe; Huang, Jianhui; Han, Xingguo; Lin, Guanghui; Zheng, Fawen; Li, Yuncong

2014-01-01

Understanding the carbon sources supporting aquatic consumers in large rivers is essential for the protection of ecological integrity and for wildlife management. The relative importance of terrestrial and algal carbon to the aquatic food webs is still under intensive debate. The Yangtze River is the largest river in China and the third longest river in the world. The completion of the Three Gorges Dam (TGD) in 2003 has significantly altered the hydrological regime of the middle Yangtze River, but its immediate impact on carbon sources supporting the river food web is unknown. In this study, potential production sources from riparian and the main river channel, and selected aquatic consumers (invertebrates and fish) at an upstream constricted-channel site (Luoqi), a midstream estuarine site (Huanghua) and a near dam limnetic site (Maoping) of the TGD were collected for stable isotope (δ13C and δ15N) and IsoSource analyses. Model estimates indicated that terrestrial plants were the dominant carbon sources supporting the consumer taxa at the three study sites. Algal production appeared to play a supplemental role in supporting consumer production. The contribution from C4 plants was more important than that of C3 plants at the upstream site while C3 plants were the more important carbon source to the consumers at the two impacted sites (Huanghua and Maoping), particularly at the midstream site. There was no trend of increase in the contribution of autochthonous production from the upstream to the downstream sites as the flow rate decreased dramatically along the main river channel due to the construction of TGD. Our findings, along with recent studies in rivers and lakes, are contradictory to studies that demonstrate the importance of algal carbon in the aquatic food web. Differences in system geomorphology, hydrology, habitat heterogeneity, and land use may account for these contradictory findings reported in various studies. PMID:25047656

Terrestrial contributions to the aquatic food web in the middle Yangtze River.

PubMed

Wang, Jianzhu; Gu, Binhe; Huang, Jianhui; Han, Xingguo; Lin, Guanghui; Zheng, Fawen; Li, Yuncong

2014-01-01

Understanding the carbon sources supporting aquatic consumers in large rivers is essential for the protection of ecological integrity and for wildlife management. The relative importance of terrestrial and algal carbon to the aquatic food webs is still under intensive debate. The Yangtze River is the largest river in China and the third longest river in the world. The completion of the Three Gorges Dam (TGD) in 2003 has significantly altered the hydrological regime of the middle Yangtze River, but its immediate impact on carbon sources supporting the river food web is unknown. In this study, potential production sources from riparian and the main river channel, and selected aquatic consumers (invertebrates and fish) at an upstream constricted-channel site (Luoqi), a midstream estuarine site (Huanghua) and a near dam limnetic site (Maoping) of the TGD were collected for stable isotope (δ13C and δ15N) and IsoSource analyses. Model estimates indicated that terrestrial plants were the dominant carbon sources supporting the consumer taxa at the three study sites. Algal production appeared to play a supplemental role in supporting consumer production. The contribution from C4 plants was more important than that of C3 plants at the upstream site while C3 plants were the more important carbon source to the consumers at the two impacted sites (Huanghua and Maoping), particularly at the midstream site. There was no trend of increase in the contribution of autochthonous production from the upstream to the downstream sites as the flow rate decreased dramatically along the main river channel due to the construction of TGD. Our findings, along with recent studies in rivers and lakes, are contradictory to studies that demonstrate the importance of algal carbon in the aquatic food web. Differences in system geomorphology, hydrology, habitat heterogeneity, and land use may account for these contradictory findings reported in various studies.

Rapid water quality change in the Elwha River estuary complex during dam removal

USGS Publications Warehouse

Foley, Melissa M.; Duda, Jeffrey J.; Beirne, Matthew M.; Paradis, Rebecca; Ritchie, Andrew; Warrick, Jonathan A.

2015-01-01

Dam removal in the United States is increasing as a result of structural concerns, sedimentation of reservoirs, and declining riverine ecosystem conditions. The removal of the 32 m Elwha and 64 m Glines Canyon dams from the Elwha River in Washington, U.S.A., was the largest dam removal project in North American history. During the 3 yr of dam removal—from September 2011 to August 2014—more than ten million cubic meters of sediment was eroded from the former reservoirs, transported downstream, and deposited throughout the lower river, river delta, and nearshore waters of the Strait of Juan de Fuca. Water quality data collected in the estuary complex at the mouth of the Elwha River document how conditions in the estuary changed as a result of sediment deposition over the 3 yr the dams were removed. Rapid and large-scale changes in estuary conditions—including salinity, depth, and turbidity—occurred 1 yr into the dam removal process. Tidal propagation into the estuary ceased following a large sediment deposition event that began in October 2013, resulting in decreased salinity, and increased depth and turbidity in the estuary complex. These changes have persisted in the system through dam removal, significantly altering the structure and functioning of the Elwha River estuary ecosystem.

Particulate organic matter predicts bacterial productivity in a river dominated estuary

NASA Astrophysics Data System (ADS)

Crump, B. C.

2015-12-01

Estuaries act as coastal filters for organic and inorganic fluvial materials in which microbial, biogeochemical, and ecological processes combine to transform organic matter and nutrients prior to export to the coastal ocean. The function of this estuarine 'bioreactor' is linked to the residence times of those materials and to rates of microbial heterotrophic activity. Our ability to forecast the impact of global change on estuarine bioreactor function requires an understanding of the basic controls on microbial community activity and diversity. In the Columbia River estuary, the microbial community undergoes a dramatic seasonal shift in species composition during which a spring bacterioplankton community, dominated by Flavobacteriaceae and Oceanospirillales, is replaced by a summer community, dominated by Rhodobacteraceae and several common marine taxa. This annual shift occurs in July, following the spring freshet, when river flow and river chlorophyll concentration decrease and when estuarine water residence time increases. Analysis of a large dataset from 17 research cruises (1990-2014) showed that the composition of particulate organic matter in the estuary changes after the freshet with decreasing organic carbon and nitrogen content, and increasing contribution of marine and autochthonous estuarine organic matter (based on PO13C and pigment ratios). Bacterial production rates (measured as leucine or thymidine incorporation rates) in the estuary respond to this change, and correlate strongly with labile particulate nitrogen concentration and temperature during individual sampling campaigns, and with the concentration of chlorophyll in the Columbia River across all seasons. Regression models suggest that the concentration of labile particulate nitrogen and the rate of bacterial production can be predicted from sensor measurements of turbidity, salinity, and temperature in the estuary and chlorophyll in the river. These results suggest that the quality of

Three-dimensional Virtual Simulation of Oil Spill of Yangtze River in Chongqing Area Based on Emergency Decision

NASA Astrophysics Data System (ADS)

Chen, Shuzhe; Huang, Liwen

the river of Yangtze River in Chongqing area is continuous curved. Hydrology and channel situation is complex, and the transportation is busy. With the increasing of shipments of hazardous chemicals year by year, oil spill accident risk is rising. So establishment of three-dimensional virtual simulation of oil spill and its application in decision-making has become an urgent task. This paper detailed the process of three-dimensional virtual simulation of oil spill and established a system of three-dimensional virtual Simulation of oil spill of Yangtze River in Chongqing area by establishing an oil spill model of the Chongqing area based on oil particles model, and the system has been used in emergency decision to provide assistance for the oil spill response.

Processing and Analysis of Multibeam Sonar Data and Images near the Yellow River Estuary

NASA Astrophysics Data System (ADS)

Tang, Q.

2017-12-01

Yellow River Estuary is a typical high-suspended particulate matter estuary in the world. A lot of sediments from Yellow River and other substances produced by human activity cause high-concentration suspended matter and depositional system in the estuary and adjacent water area. Multibeam echo sounder (MBES) was developed in the 1970s, and it not only provided high-precision bathymetric data, but also provided seabed backscatter strength data and water column data with high temporal and spatial resolution. Here, based on high-precision sonar data of the seabed and water column collected by SeaBat7125 MBES system near the Yellow River Estuary, we use advanced data and image processing methods to generate seabed sonar images and water suspended particulate matter acoustic images. By analyzing these data and images, we get a lot of details of the seabed and whole water column features, and we also acquire their shape, size and basic physical characteristics of suspended particulate matters in the experiment area near the Yellow River Estuary. This study shows great potential for monitoring suspended particulate matter use MBES, and the research results will contribute to a comprehensive understanding of sediment transportation, evolution of river trough and shoal in Yellow River Estuary.

Continuous resistivity profiling data from the Corsica River Estuary, Maryland

USGS Publications Warehouse

Cross, V.A.; Bratton, J.F.; Worley, C.R.; Crusius, John; Kroeger, K.D.

2011-01-01

Submarine groundwater discharge (SGD) into Maryland's Corsica River Estuary was investigated as part of a larger study to determine its importance in nutrient delivery to the Chesapeake Bay. The Corsica River Estuary represents a coastal lowland setting typical of much of the eastern bay. An interdisciplinary U.S. Geological Survey (USGS) science team conducted field operations in the lower estuary in April and May 2007. Resource managers are concerned about nutrients that are entering the estuary via SGD that may be contributing to eutrophication, harmful algal blooms, and fish kills. Techniques employed in the study included continuous resistivity profiling (CRP), piezometer sampling of submarine groundwater, and collection of a time series of radon tracer activity in surface water. A CRP system measures electrical resistivity of saturated subestuarine sediments to distinguish those bearing fresh water (high resistivity) from those with saline or brackish pore water (low resistivity). This report describes the collection and processing of CRP data and summarizes the results. Based on a grid of 67.6 kilometers of CRP data, low-salinity (high-resistivity) groundwater extended approximately 50-400 meters offshore from estuary shorelines at depths of 5 to >12 meters below the sediment surface, likely beneath a confining unit. A band of low-resistivity sediment detected along the axis of the estuary indicated the presence of a filled paleochannel containing brackish groundwater. The meandering paleochannel likely incised through the confining unit during periods of lower sea level, allowing the low-salinity groundwater plumes originating from land to mix with brackish subestuarine groundwater along the channel margins and to discharge. A better understanding of the spatial variability and geological controls of submarine groundwater flow beneath the Corsica River Estuary could lead to improved models and mitigation strategies for nutrient over-enrichment in the

A comparison of CO2 dynamics and air-water fluxes in a river-dominated estuary and a mangrove-dominated marine estuary

NASA Astrophysics Data System (ADS)

Akhand, Anirban; Chanda, Abhra; Manna, Sudip; Das, Sourav; Hazra, Sugata; Roy, Rajdeep; Choudhury, S. B.; Rao, K. H.; Dadhwal, V. K.; Chakraborty, Kunal; Mostofa, K. M. G.; Tokoro, T.; Kuwae, Tomohiro; Wanninkhof, Rik

2016-11-01

The fugacity of CO2 (fCO2 (water)) and air-water CO2 flux were compared between a river-dominated anthropogenically disturbed open estuary, the Hugli, and a comparatively pristine mangrove-dominated semiclosed marine estuary, the Matla, on the east coast of India. Annual mean salinity of the Hugli Estuary (≈7.1) was much less compared to the Matla Estuary (≈20.0). All the stations of the Hugli Estuary were highly supersaturated with CO2 (annual mean 2200 µatm), whereas the Matla was marginally oversaturated (annual mean 530 µatm). During the postmonsoon season, the outer station of the Matla Estuary was under saturated with respect to CO2 and acted as a sink. The annual mean CO2 emission from the Hugli Estuary (32.4 mol C m-2 yr-1) was 14 times higher than the Matla Estuary (2.3 mol C m-2 yr-1). CO2 efflux rate from the Hugli Estuary has increased drastically in the last decade, which is attributed to increased runoff from the river-dominated estuary.

Spatial-temporal evolution of the eastern Nanhui mudflat in the Changjiang (Yangtze River) Estuary under intensified human activities

NASA Astrophysics Data System (ADS)

Zhang, Xiaodong; Zhang, Yexin; Zhu, Longhai; Chi, Wanqing; Yang, Zuosheng; Wang, Biying; Lv, Kai; Wang, Hongmin; Lu, Zhiyong

2018-05-01

The eastern Nanhui mudflat (ENM), located in the southern flank of the Changjiang (Yangtze River) Estuary, plays a key role in storm protection, defense against sea level rise, and land resource provision for Shanghai, China's largest city. Recently, there has been a great deal of concern for its evolutionary fate, since a drastic reduction in the Changjiang sediment discharge rate and an increased number of estuarine enclosures might negatively impact the environmental protection functions that this mudflat provides. In this paper, a novel method, which employed the envelope lines of instantaneous shoreline positions identified in 436 Landsat satellite images from 1975 to 2016, was used to demonstrate the evolution of the mudflat high and low tide lines in a detailed, quantitative way. Our study reveals the southeast progradation rate of the mudflat doubled from 24 m/yr in 713-1974 CE to 49 m/yr in 1975-1995 CE, probably due to the influence of the estuarine turbidity maximum zone shifting to the ENM. Under the ample sediment input directly from the turbidity maximum zone, the spatial evolution of the ENM was governed predominantly by the changing morphology of the South Passage due to the quick progradation of the ENM, which narrowed the South Passage by pushing the South Passage Trumpet southeastward. Therefore, the ENM experienced rapid accretion during 1975-2016. The accretion rate of the high tide line increased 2-13 times due to vegetation and intertidal enclosures, resulting in the rapid reduction of the intertidal area. The area decreased from 97 km2 in 1976 to 66 km2 in 1995, mainly due to vegetation, and continued decreasing to 12 km2 in 2006 due to the intertidal enclosures. In contrast, the accretion rate of the low tide line increased by 25 times due to subtidal enclosures and caused the intertidal area increased to 78 km2 in 2015. The almost disappeared intertidal zones in 2006 reappeared. However, this reappearance might be a temporary transitional

Heavy metal anomalies in the Tinto and Odiel River and estuary system, Spain

USGS Publications Warehouse

Nelson, C.H.; Lamothe, P.J.

1993-01-01

The Tinto and Odiel rivers drain 100 km from the Rio Tinto sulphide mining district, and join at a 20-km long estuary entering the Atlantic Ocean. A reconnaissance study of heavy metal anomalies in channel sand and overbank mud of the river and estuary by semi-quantitative emission dc-arc spectrographic analysis shows the following upstream to downstream ranges in ppm (??g g-1): As 3,000 to <200, Cd 30 to <0.1, Cu 1,500 to 10, Pb 2,000 to <10, Sb 3000 to <150, and Zn 3,000 to <200. Organic-rich (1.3-2.6% total organic carbon, TOC), sandysilty overbank clay has been analyzed to represent suspended load materials. The high content of heavy metals in the overbank clay throughout the river and estuary systems indicates the importance of suspended sediment transport for dispersing heavy metals from natural erosion and anthropogenic mining activities of the sulfide deposit. The organic-poor (0.21-0.37% TOC) river bed sand has been analyzed to represent bedload transport of naturally-occurring sulfide minerals. The sand has high concentrations of metals upstream but these decrease an order of magnitude in the lower estuary. Although heavy metal contamination of estuary mouth beach sand has been diluted to background levels estuary mud exhibits increased contamination apparently related to finer grain size, higher organic carbon content, precipitation of river-borne dissolved solids, and input of anthropogenic heavy metals from industrial sources. The contaminated estuary mud disperses to the inner shelf mud belt and offshore suspended sediment, which exhibit metal anomalies from natural erosion and mining of upstream Rio Tinto sulphide lode sources (Pb, Cu, Zn) and industrial activities within the estuary (Fe, Cr, Ti). Because heavy metal contamination of Tinto-Odiel river sediment reaches or exceeds the highest levels encountered in other river sediments of Spain and Europe, a detailed analysis of metals in water and suspended sediment throughout the system, and

Editorial: Eutrophication and hypoxia and their impacts on the ecosystem of the Changjiang Estuary and adjacent coastal environment

NASA Astrophysics Data System (ADS)

Zhang, Jing; Xiao, Tian; Huang, Daji; Liu, Su Mei; Fang, Jianguang

2016-02-01

The Changjiang (Yangtze River) Estuary plays an important role in the land-ocean interactions of East Asia, particularly in regard to the fate of land-derived materials and their impact on marine ecosystems in the Northwest Pacific Ocean. The 12 papers included in this special issue describe results from the MEcoPAM Study, an IMBER-China project, which occurred in 2011-2015. This project used a multi-disciplinary approach to understand ecosystem function of the Changjiang Estuary in response to multiple stressors (i.e. combined external forcings). The results presented here show that human activities in the watersheds have greatly changed the flux and variation of dissolved and particulate materials from the river. Further interactions between the Changjiang Watersheds and the East China Sea can dramatically modify the pathways of biogeochemistry and food web dynamics of the estuary and adjacent coastal environment at seasonal and inter-annual scales.

Benthic phosphorus regeneration in the Potomac River Estuary

USGS Publications Warehouse

Callender, E.

1982-01-01

The flux of dissolved reactive phosphate from Potomac riverine and estuarine sediments is controlled by processes occurring at the water-sediment interface and within surficial sediment. In situ benthic fluxes (0.1 to 2.0 mmoles m-2 day-1) are generally five to ten times higher than calculated diffusive fluxes (0.020 to 0.30 mmoles m-2 day-1). The discrepancy between the two flux estimates is greatest in the transition zone (river mile 50 to 70) and is attributd to macrofaunal irrigation. Both in situ and diffusive fluxes of dissolved reactive phosphate from Potomac tidal river sediments are low while those from anoxic lower estuarine sediments are high. The net accumulation rate of phosphorus in benthic sediment exhibits an inverse pattern. Thus a large fraction of phosphorus is retained by Potomac tidal river sediments, which contain a surficial oxidized layer and oligochaete worms tolerant of low oxygen conditions, and a large fraction of phosphorus is released from anoxic lower estuary sediments. Tidal river sediment pore waters are in equilibrium with amorphous Fe (OH)3 while lower estuary pore waters are significantly undersaturated with respect to this phase. Benthic regeneration of dissolved reactive phosphorus is sufficient to supply all the phosphorus requirements for net primary production in the lower tidal river and transition-zone waters of the Potomac River Estuary. Benthic regeneration supplies approximately 25% as much phosphorus as inputs from sewage treatment plants and 10% of all phosphorus inputs to the tidal Potomac River. When all available point source phosphorus data are put into a steady-state conservation of mass model and reasonable coefficients for uptake of dissolved phosphorus, remineralization of particulate phosphorus, and sedimentation of particulate phosphorus are used in the model, a reasonably accurate simulation of dissolved and particulate phosphorus in the water column is obtained for the summer of 1980. ?? 1982 Dr W. Junk

Impact of Yangtze River Water Transfer on the Water Quality of the Lixia River Watershed, China

PubMed Central

Ma, Xiaoxue; Wang, Lachun; Wu, Hao; Li, Na; Ma, Lei; Zeng, Chunfen; Zhou, Yi; Yang, Jun

2015-01-01

To improve water quality and reduce the negative impacts of sudden inputs of water pollution in the Lixia River watershed, China, a series of experimental water transfers from the Yangtze River to the Lixia River were conducted from 2 December 2006 to 7 January 2007. Water samples were collected every six days at 55 monitoring sites during this period. Eight water parameters (water temperature, pH, dissolved oxygen (DO), chemical oxygen demand (COD), potassium permanganate index (CODMn), ammonia nitrogen (NH4 +-N), electrical conductivity (EC), and water transparency (WT)) were analyzed to determine changes in nutrient concentrations during water transfers. The comprehensive pollution index (Pi) and single-factor (Si) evaluation methods were applied to evaluate spatio-temporal patterns of water quality during water transfers. Water quality parameters displayed different spatial and temporal distribution patterns within the watershed. Water quality was improved significantly by the water transfers, especially for sites closer to water intake points. The degree of improvement is positively related to rates of transfer inflow and drainage outflow. The effects differed for different water quality parameters at each site and at different water transfer times. There were notable decreases in NH4 +-N, DO, COD, and CODMn across the entire watershed. However, positive effects on EC and pH were not observed. It is concluded that freshwater transfers from the Yangtze River can be used as an emergency measure to flush pollutants from the Lixia River watershed. Improved understanding of the effects of water transfers on water quality can help the development and implementation of effective strategies to improve water quality within this watershed. PMID:25835525

[Study of the fluorescence characteristics of DOM from the Yangtze River and Jialing River around Chongqing's urban areas].

PubMed

Ji, Fang-ying; Li, Si; Zhou, Guang-ming; Yu, Dan-ni; Wang, Tu-jin; Cao, Lin; Tan, Xue-mei; Yang, Da-cheng; Zhou, Xiao-yi

2010-01-01

The fluorescence emission and excitation emission matrix (EEM) technologies were used to characterize the dissolved organic matter (DOM) in the water body of the Yangtze River and Jialing River around the Chongqing urban areas from April to August 2008. Concerning about the accidents of the Wenchuan's Earthquake in May and Tangjiashan Yansaihu's effects in June, and the high water period time in the summer in two months of July and August, from the EEM obtained from each sampling station and time, the composition, distribution and their changing features of the DOM in the two rivers were investigated as combined with the water samples' environmental parameters such as pH, DO, DOC with EEM's fingerprint features, f(450/500) etc; finally the bio-environment behavior effects of the three types of fluorescence peaks were elaborated, where humic-like, fulvic-like, and protein-like from the five sampling stations' EEMs during the five months were given detailed representation. From the experimental results obtained, the fluorescence peaks are mainly composed of two types of fluorophores: humic-like and protein-like in the two rivers around the Chongqing urban areas during the investigation in five months, the protein-like's peaks value in Jialing River is higher than the values in the Yangtze River, and all the fluorescence peaks in the two Rivers' water body decrease more or less after the two Rivers join in Chun Tan sampling station; the protein-like peak is notably higher after the "5 x 12" earthquake period time including May and June and high water period time, which mainly originated from terrestrial sources, but its intensities decreased observably while the water bodies of the two rivers joining together in the Chao Tianmen and Chun Tan's sampling station.

Case study on rehabilitation of a polluted urban water body in Yangtze River Basin.

PubMed

Wu, Juan; Cheng, Shuiping; Li, Zhu; Guo, Weijie; Zhong, Fei; Yin, Daqiang

2013-10-01

In the past three decades, the fast development of economy and urbanization has caused increasingly severe pollutions of urban water bodies in China. Consequently, eutrophication and deterioration of aquatic ecosystem, which is especially significant for aquatic vegetation, inevitably became a pervasive problem across the Yangtze River Basin. To rehabilitate the degraded urban water bodies, vegetation replanting is an important issue to improve water quality and to rehabilitate ecosystem. As a case study, a representative polluted urban river, Nanfeihe River, in Hefei City, Anhui Province, was chosen to be a rehabilitation target. In October 2009 and May 2010, 13 species of indigenous and prevalent macrophytes, including seven species emergent, one species floating leaved, and five species submersed macrophytes, were planted along the bank slopes and in the river. Through 1.5 years' replanting practice, the water quality and biodiversity of the river had been improved. The concentrations of total nitrogen (TN), total phosphorus (TP), and ammonia nitrogen (NH4 (+)-N) declined by 46.0, 39.5, and 60.4 %, respectively. The species of macrophytes increased from 14 to 60, and the biodiversity of phytoplankton rose significantly in the river (p<0.05). The biomasses of zooplankton and benthos were also improved after the vegetation replanting. The study confirmed that vegetation replanting could alleviate the increasing water pollution and rehabilitate the degraded aquatic ecosystem. The case study would be an example for polluted urban waters restoration in the middle-downstream area of Yangtze River Base.

Variation of Temperature and Precipitation in Urban Agglomeration and Prevention Suggestion of Waterlogging in Middle and Lower Reaches of Yangtze River

NASA Astrophysics Data System (ADS)

Na, Liu; Youjie, Jin; Jiaqi, Dai

2018-03-01

The variation trend of temperature and precipitation during flood season in the middle and lower reaches of the Yangtze River basin in recent 50 years and change characteristics of rainfall in five typical flood prone cities are analysed. Aiming at waterlogging problems in the urban agglomeration of middle and lower reaches of the Yangtze River, the comprehensive prevention and control suggestions are put forward. The results showed that: the temperature trend in the basin decreased and then increased, and the precipitation showed a downward-rising-downward trend, no mutation occurred; The incidence of heavy rainfall events in the five typical cities with daily rainfall more than 50mm showed an upward trend, and increased significantly after 2002. The intensity of precipitation increased gradually. Climate change makes urban agglomeration waterlogging disasters become increasingly prominent in the middle and lower reaches of the Yangtze River.

Occurrence of pharmaceuticals and personal care products and associated environmental risks in the central and lower Yangtze river, China.

PubMed

Wu, Chenxi; Huang, Xiaolong; Witter, Jason D; Spongberg, Alison L; Wang, Kexiong; Wang, Ding; Liu, Jiantong

2014-08-01

Pharmaceutical and personal care products (PPCPs) residues are being highlighted around the world as of emerging concern in surface waters. Here the occurrence of PPCPs in the central and lower Yangtze River, along with four large freshwater lakes within the river basin (Dongting, Poyang, Tai, and Chao) was reported. Fifteen out of twenty selected PPCPs were detected in the collected surface water samples. Caffeine, paraxanthine, sulfamethazine, and clindamycin were detected with 100 percent frequency in the Yangtze River. In the river, the highest average concentration was observed for erythromycin (296 ng L(-1)), followed by caffeine (142 ng L(-1)) and paraxanthine (41 ng L(-1)). In the four lakes, total PPCP concentrations were much higher in the Chao (1547 ng L(-1)) and Tai (1087 ng L(-1)) lakes compared to the Poyang (108 ng L(-1)) and Dongting (137 ng L(-1)) lakes. Lincomycin and clindamycin were most abundant in the lakes, especially in the Tai Lake. Environmental risk assessment for the worst case scenario was assessed using calculated risk quotients, and indicates a high environmental risk of erythromycin and clarithromycin in the Yangtze River, clarithromycin in the Chao Lake, and clindamycin in the Tai Lake. Copyright © 2014 Elsevier Inc. All rights reserved.

Geochemistry of tin in rivers and estuaries

NASA Astrophysics Data System (ADS)

Byrd, James T.; Andreae, Meinrat O.

1986-05-01

On the basis of measurements from a large number of rivers from pristine and polluted regions, we estimate the riverine fluxes of tin to the oceans to be 0.76 × 10 6molyr-1 for the dissolved fraction and 300-600 × 10 6 mol yr -1 for the paniculate fraction. The paniculate flux agrees with the flux calculated from denudation rates. Estuaries were found not to have a large effect upon the transport of tin to the oceans. Evidence for the remobilization of tin was found in an estuary that is highly polluted with tin from mining and smelting activities. Monobutyltin was found to be present in polluted estuaries and is presumed to be a degradation product of tributyltin additives to antifouling paint.

Is ENSO related to 2015 Easter Star Capsized on the Yangtze River of China?

NASA Astrophysics Data System (ADS)

Xie, P.

2015-12-01

Natural disasters have profound effects on community security and economic damage of China's Hubei province. In June 1st, 2015, a cruise ship, Easter Star, capsized on Yangtze River in Hubei province with 442 died. What reason gives rise to such strong convection causing ship sunk? Based on the wind disasters of Hubei province happened in 1963-2015, this study analyzes their features bytime-series regression, and correlates them to global El Niño/Southern Oscillation (ENSO) events. The compared results demonstrated that the wind disasters shown an increasing tendency. There are two peaks corresponding to the strongest ENSO peaks during the past 50 years; each peak lasts two-three years. The facts demonstrated an essential linear relation between the ENSO phenomena and wind disasters in Hubei province. 2015 Easter Star capsized happened at current El Niño event in 2014-2015. We also observed that the historical wind disasters appeared in seasonal variation. Over 90% events concentrated in spring and summer; very few events happened in autumn and winter. Moreover, the disasters depend on the geographic conditions. Most disasters concentrated in four zones, named as Xingshan-Baokang, Xuanen, Wufeng-Yichang, Jingzhou-Gongan, in which Xingshan and Changyang are the two most density of zones. Yangtze River provides an air flowing conduct for strong convective winds. It can be concluded that the strong convection causing 2015 Easter Star capsized is related to current global ENSO phenomenon.Keywords: ENSO, wind disaster, time-series regression analysis, Easter Star, Yangtze River, Hubei Province,

Genetic Diversity of Daphnia pulex in the Middle and Lower Reaches of the Yangtze River

PubMed Central

Wang, Wenping; Zhang, Kun; Deng, Daogui; Zhang, Ya-Nan; Peng, Shuixiu; Xu, Xiaoxue

2016-01-01

Increased human activities and environmental changes may lead to genetic diversity variations of Cladocerans in water. Daphnia pulex are distributed throughout the world and often regarded as a model organism. The 16S rDNA, cytochrome c oxidase subunit I (COI), and 18S genes were used as molecular marks. The genetic diversity and phylogeny of D. pulex obtained from 10 water bodies in the middle and lower reaches of the Yangtze River were studied. For 16S rDNA, COI gene, and 18S gene, the A+T content (65.4%, 58.4%, and 54.6%) was significantly higher than the G+C content (34.6%, 41.6% and 45.4%). This result was consistent with higher A and T contents among invertebrates. Based on the genetic distances of 16S rDNA and COI genes, the genetic differences of D. pulex from 10 water bodies located in the middle and lower reaches of the Yangtze River in China was minimal (0%–0.8% for 16S rDNA and 0%–1.5% for COI gene). However, D. pulex evolved into two branches in the phylogenetic trees, which coincided with its geographical distribution. Compared with D. pulex from other countries, the average genetic distance of D. pulex obtained from 10 water bodies in the middle and lower reaches of the Yangtze River reached 9.1%–10.5%, thereby indicating that D. pulex may have evolved into different subspecies. PMID:27015539

Decreasing reference evapotranspiration in a warming climate - A case of Changjiang (Yangtze) River catchment during 1970-2000

NASA Astrophysics Data System (ADS)

Xu, C. Y.; Gong, L. B.; Tong, J.; Chen, D. L.

2006-07-01

This study deals with temporal trends in the Penman-Monteith reference evapotranspiration estimated from standard meteorological observations, observed pan evaporation, and four related meteorological variables during 1970-2000 in the Yangtze River catchment. Relative contributions of the four meteorological variables to changes in the reference evapotranspiration are quantified. The results show that both the reference evapotranspiration and the pan evaporation have significant. decreasing trends in the upper, the middle as well as in the whole Changjiang (Yangtze) River catchment at the 5% significance level, while the air temperature shows a significant increasing trend. The decreasing trend detected in the reference evapotranspiration can be attributed to the significant decreasing trends in the net radiation and the wind speed.

From headwaters to coast: Influence of human activities on water quality of the Potomac River Estuary

USGS Publications Warehouse

Bricker, Suzanne B.; Rice, Karen C.; Bricker, Owen P.

2014-01-01

The natural aging process of Chesapeake Bay and its tributary estuaries has been accelerated by human activities around the shoreline and within the watershed, increasing sediment and nutrient loads delivered to the bay. Riverine nutrients cause algal growth in the bay leading to reductions in light penetration with consequent declines in sea grass growth, smothering of bottom-dwelling organisms, and decreases in bottom-water dissolved oxygen as algal blooms decay. Historically, bay waters were filtered by oysters, but declines in oyster populations from overfishing and disease have led to higher concentrations of fine-sediment particles and phytoplankton in the water column. Assessments of water and biological resource quality in Chesapeake Bay and tributaries, such as the Potomac River, show a continual degraded state. In this paper, we pay tribute to Owen Bricker’s comprehensive, holistic scientific perspective using an approach that examines the connection between watershed and estuary. We evaluated nitrogen inputs from Potomac River headwaters, nutrient-related conditions within the estuary, and considered the use of shellfish aquaculture as an in-the-water nutrient management measure. Data from headwaters, nontidal, and estuarine portions of the Potomac River watershed and estuary were analyzed to examine the contribution from different parts of the watershed to total nitrogen loads to the estuary. An eutrophication model was applied to these data to evaluate eutrophication status and changes since the early 1990s and for comparison to regional and national conditions. A farm-scale aquaculture model was applied and results scaled to the estuary to determine the potential for shellfish (oyster) aquaculture to mediate eutrophication impacts. Results showed that (1) the contribution to nitrogen loads from headwater streams is small (about 2 %) of total inputs to the Potomac River Estuary; (2) eutrophic conditions in the Potomac River Estuary have improved in

Ship-based MAX-DOAS measurements of tropospheric NO2, SO2, and HCHO distribution along the Yangtze River

NASA Astrophysics Data System (ADS)

Hong, Qianqian; Liu, Cheng; Chan, Ka Lok; Hu, Qihou; Xie, Zhouqing; Liu, Haoran; Si, Fuqi; Liu, Jianguo

2018-04-01

In this paper, we present ship-based Multi-Axis Differential Optical Absorption Spectroscopy (MAX-DOAS) measurements of tropospheric trace gases' distribution along the Yangtze River during winter 2015. The measurements were performed along the Yangtze River between Shanghai and Wuhan, covering major industrial areas in eastern China. Tropospheric vertical column densities (VCDs) of nitrogen dioxide (NO2), sulfur dioxide (SO2), and formaldehyde (HCHO) were retrieved using the air mass factor calculated by the radiative transfer model. Enhanced tropospheric NO2 and SO2 VCDs were detected over downwind areas of industrial zones over the Yangtze River. In addition, spatial distributions of atmospheric pollutants are strongly affected by meteorological conditions; i.e., positive correlations were found between concentration of pollutants and wind speed over these areas, indicating strong influence of transportation of pollutants from high-emission upwind areas along the Yangtze River. Comparison of tropospheric NO2 VCDs between ship-based MAX-DOAS and Ozone Monitoring Instrument (OMI) satellite observations shows good agreement with each other, with a Pearson correlation coefficient (R) of 0.82. In this study, the NO2 / SO2 ratio was used to estimate the relative contributions of industrial sources and vehicle emissions to ambient NO2 levels. Analysis results of the NO2 / SO2 ratio show a higher contribution of industrial NO2 emissions in Jiangsu Province, while NO2 levels in Jiangxi and Hubei provinces are mainly related to vehicle emissions. These results indicate that different pollution control strategies should be applied in different provinces. In addition, multiple linear regression analysis of ambient carbon monoxide (CO) and odd oxygen (Ox) indicated that the primary emission and secondary formation of HCHO contribute 54.4 ± 3.7 % and 39.3 ± 4.3 % to the ambient HCHO, respectively. The largest contribution from primary emissions in winter suggested that

Assessing the potential for change in the middle Yangtze River channel following impoundment of the Three Gorges Dam

NASA Astrophysics Data System (ADS)

Yuan, Wenhao; Yin, Daowei; Finlayson, Brian; Chen, Zhongyuan

2012-04-01

The geomorphic impacts of dams on downstream river channels are complex, not readily predictable for specific cases, but widely reported in the literature. For the Three Gorges Dam on the Yangtze (Changjiang) River in China, no studies of the impact of the changed flow and sediment conditions below the dam on the behaviour of the channel were included in the pre-dam feasibility report. We have assembled a database of flow and sediment data for the middle Yangtze River from Yichang to Hankou and used this to analyse changes following the closure of the dam. While total flow is little affected, the operating strategy for the dam that provides for storage of part of the summer high flows to maintain hydroelectric power generation in winter (the low flow season) is reflected in changes to the seasonal distribution of flow below the dam. We calculated potential sediment carrying capacity and compared it with measured sediment concentrations for both pre- and post-dam conditions. While channel sedimentation is indicated along the middle Yangtze for pre-dam conditions, scour is indicated for post-dam conditions, highest at Yichang immediately below the dam and decreasing downstream.

Effect of conservation efforts and ecological variables on waterbird population sizes in wetlands of the Yangtze River

PubMed Central

Zhang, Yong; Jia, Qiang; Prins, Herbert H. T.; Cao, Lei; de Boer, Willem Frederik

2015-01-01

Forage quality and availability, climatic factors, and a wetland’s conservation status are expected to affect the densities of wetland birds. However, the conservation effectiveness is often poorly studied. Here, using twelve years’ census data collected from 78 wetlands in the Yangtze River floodplain, we aimed to understand the effect of these variables on five Anatidae species, and evaluate the effectiveness of the conservation measures by comparing population trends of these species among wetlands that differ in conservations status. We showed that the slope angle of a wetland and the variation thereof best explain the differences in densities of four species. We also found that the population abundances of the Anatidae species generally declined in wetlands along the Yangtze River floodplain over time, with a steeper decline in wetlands with a lower protection status, indicating that current conservation policies might deliver benefits for wintering Anatidae species in China, as population sizes of the species were buffered to some extent against decline in numbers in wetlands with a higher level protection status. We recommend several protection measures to stop the decline of these Anatidae species in wetlands along the Yangtze River floodplain, which are of great importance for the East Asian-Australasian Flyway. PMID:26601785

Effect of conservation efforts and ecological variables on waterbird population sizes in wetlands of the Yangtze River

NASA Astrophysics Data System (ADS)

Zhang, Yong; Jia, Qiang; Prins, Herbert H. T.; Cao, Lei; de Boer, Willem Frederik

2015-11-01

Forage quality and availability, climatic factors, and a wetland’s conservation status are expected to affect the densities of wetland birds. However, the conservation effectiveness is often poorly studied. Here, using twelve years’ census data collected from 78 wetlands in the Yangtze River floodplain, we aimed to understand the effect of these variables on five Anatidae species, and evaluate the effectiveness of the conservation measures by comparing population trends of these species among wetlands that differ in conservations status. We showed that the slope angle of a wetland and the variation thereof best explain the differences in densities of four species. We also found that the population abundances of the Anatidae species generally declined in wetlands along the Yangtze River floodplain over time, with a steeper decline in wetlands with a lower protection status, indicating that current conservation policies might deliver benefits for wintering Anatidae species in China, as population sizes of the species were buffered to some extent against decline in numbers in wetlands with a higher level protection status. We recommend several protection measures to stop the decline of these Anatidae species in wetlands along the Yangtze River floodplain, which are of great importance for the East Asian-Australasian Flyway.

Effect of conservation efforts and ecological variables on waterbird population sizes in wetlands of the Yangtze River.

PubMed

Zhang, Yong; Jia, Qiang; Prins, Herbert H T; Cao, Lei; de Boer, Willem Frederik

2015-11-25

Forage quality and availability, climatic factors, and a wetland's conservation status are expected to affect the densities of wetland birds. However, the conservation effectiveness is often poorly studied. Here, using twelve years' census data collected from 78 wetlands in the Yangtze River floodplain, we aimed to understand the effect of these variables on five Anatidae species, and evaluate the effectiveness of the conservation measures by comparing population trends of these species among wetlands that differ in conservations status. We showed that the slope angle of a wetland and the variation thereof best explain the differences in densities of four species. We also found that the population abundances of the Anatidae species generally declined in wetlands along the Yangtze River floodplain over time, with a steeper decline in wetlands with a lower protection status, indicating that current conservation policies might deliver benefits for wintering Anatidae species in China, as population sizes of the species were buffered to some extent against decline in numbers in wetlands with a higher level protection status. We recommend several protection measures to stop the decline of these Anatidae species in wetlands along the Yangtze River floodplain, which are of great importance for the East Asian-Australasian Flyway.

Direct Detection of Potential Pyrethroids in Yangtze River via an Imprinted Multilayer Phosphorescence Probe.

PubMed

Chen, Li; Lv, Xiaodong; Dai, Jiangdong; Sun, Lin; Huo, Pengwei; Li, Chunxiang; Yan, Yongsheng

2018-01-01

A novel tailored multilayer probe for monitoring potential pyrethroids in the Yangtze River was proposed. The room-temperature phosphorescence method was applied to realize a detection strategy that is superior to the fluorescence method. Efficient Mn-doped ZnS quantum dots with uniform size of 4.6 nm were firstly coated with a mesoporous silica to obtain a suitable intermediate transition layer, then an imprinted layer containing bifenthrin specific recognition sites was anchored. Characterizations verified the multilayer structure convincingly and the detection process relied on the electron transfer-induced fluorescence quenching mechanism. Optional detection time and standard detection curve were obtained within a concentration range from 5.0 to 50 μmol L -1 . The stability was verified to be good after 12 replicates. Feasibility of the probe was proved by monitoring water samples from the Zhenjiang reach of the Yangtze River. The probe offers promise for direct bifenthrin detection in unknown environmental water with an accurate and stable phosphorescence analysis strategy.

Salt Plug Formation Caused by Decreased River Discharge in a Multi-channel Estuary

PubMed Central

Shaha, Dinesh Chandra; Cho, Yang-Ki

2016-01-01

Freshwater input to estuaries may be greatly altered by the river barrages required to meet human needs for drinking water and irrigation and prevent salt water intrusion. Prior studies have examined the salt plugs associated with evaporation and salt outwelling from tidal salt flats in single-channel estuaries. In this work, we discovered a new type of salt plug formation in the multi-channel Pasur River Estuary (PRE) caused by decreasing river discharges resulting from an upstream barrage. The formation of a salt plug in response to changes in river discharge was investigated using a conductivity-temperature-depth (CTD) recorder during spring and neap tides in the dry and wet seasons in 2014. An exportation of saline water from the Shibsa River Estuary (SRE) to the PRE through the Chunkhuri Channel occurred during the dry season, and a salt plug was created and persisted from December to June near Chalna in the PRE. A discharge-induced, relatively high water level in the PRE during the wet season exerted hydrostatic pressure towards the SRE from the PRE and thereby prevented the intrusion of salt water from the SRE to the PRE. PMID:27255892

Seasonal Distribution and Movements of Atlantic and Shortnose Sturgeon in the Penobscot River Estuary, Maine

USGS Publications Warehouse

Zydlewski, Joseph D.; Fernandes, Stephen J.; Zydlewski, Gayle B.; Wippelhauser, Gail S.; Kinnison, Michael T.

2016-01-01

Relatively little is known about the distribution and seasonal movement patterns of shortnose sturgeon Acipenser brevirostrum and Atlantic sturgeon Acipenser oxyrinchus oxyrinchus occupying rivers in the northern part of their range. During 2006 and 2007, 40 shortnose sturgeon (66–113.4 cm fork length [FL]) and 8 Atlantic sturgeon (76.2–166.2 cm FL) were captured in the Penobscot River, Maine, implanted with acoustic transmitters, and monitored using an array of acoustic receivers in the Penobscot River estuary and Penobscot Bay. Shortnose sturgeon were present year round in the estuary and overwintered from fall (mid-October) to spring (mid-April) in the upper estuary. In early spring, all individuals moved downstream to the middle estuary. Over the course of the summer, many individuals moved upstream to approximately 2 km of the downstream-most dam (46 river kilometers [rkm] from the Penobscot River mouth [rkm 0]) by August. Most aggregated into an overwintering site (rkm 36.5) in mid- to late fall. As many as 50% of the tagged shortnose sturgeon moved into and out of the Penobscot River system during 2007, and 83% were subsequently detected by an acoustic array in the Kennebec River, located 150 km from the Penobscot River estuary. Atlantic sturgeon moved into the estuary from the ocean in the summer and concentrated into a 1.5-km reach. All Atlantic sturgeon moved to the ocean by fall, and two of these were detected in the Kennebec River. Although these behaviors are common for Atlantic sturgeon, regular coastal migrations of shortnose sturgeon have not been documented previously in this region. These results have important implications for future dam removals as well as for rangewide and river-specific shortnose sturgeon management.

Leachable particulate iron in the Columbia River, estuary, and near-field plume

NASA Astrophysics Data System (ADS)

Lippiatt, Sherry M.; Brown, Matthew T.; Lohan, Maeve C.; Berger, Carolyn J. M.; Bruland, Kenneth W.

2010-03-01

This study examines the distribution of leachable particulate iron (Fe) in the Columbia River, estuary, and near-field plume. Surface samples were collected during late spring and summer of 2004-2006 as part of four River Influence on Shelf Ecosystems (RISE) cruises. Tidal amplitude and river flow are the primary factors influencing the estuary leachable particulate Fe concentrations, with greater values during high flow and/or spring tides. Near the mouth of the estuary, leachable particulate Fe [defined as the particulate Fe solubilized with a 25% acetic acid (pH 2) leach containing a weak reducing agent to reduce Fe oxyhydroxides and a short heating step to access intracellular Fe] averaged 770 nM during either spring tide or high flow, compared to 320 nM during neap tide, low flow conditions. In the near-field Columbia River plume, elevated leachable particulate Fe concentrations occur during spring tides and/or higher river flow, with resuspended shelf sediment as an additional source to the plume during periods of coastal upwelling and spring tides. Near-field plume concentrations of leachable particulate Fe (at a salinity of 20) averaged 660 nM during either spring tide or high flow, compared to 300 nM during neap tide, low flow conditions. Regardless of tidal amplitude and river flow, leachable particulate Fe concentrations in both the river/estuary and near-field plume are consistently one to two orders of magnitude greater than dissolved Fe concentrations. The Columbia River is an important source of reactive Fe to the productive coastal waters off Oregon and Washington, and leachable particulate Fe is available for solubilization following biological drawdown of the dissolved phase. Elevated leachable Fe concentrations allow coastal waters influenced by the Columbia River plume to remain Fe-replete and support phytoplankton production during the spring and summer seasons.

Microplastic-associated bacterial assemblages in the intertidal zone of the Yangtze Estuary.

PubMed

Jiang, Peilin; Zhao, Shiye; Zhu, Lixin; Li, Daoji

2018-05-15

Plastic trash is common in oceans. Terrestrial and marine ecosystem interactions occur in the intertidal zone where accumulation of plastic frequently occurs. However, knowledge of the plastic-associated microbial community (the plastisphere) in the intertidal zone is scanty. We used high-throughput sequencing to profile the bacterial communities attached to microplastic samples from intertidal locations around the Yangtze estuary in China. The structure and composition of plastisphere communities varied significantly among the locations. We found the taxonomic composition on microplastic samples was related to their sedimentary and aquatic origins. Correlation network analysis was used to identify keystone bacterial genera (e.g. Rhodobacterales, Sphingomonadales and Rhizobiales), which represented important microbial associations within the plastisphere community. Other species (i.e. potential pathogens) were considered as hitchhikers in the plastic attached microbial communities. Metabolic pathway analysis suggested adaptations of these bacterial assemblages to the plastic surface-colonization lifestyle. These adaptations included reduced "cell motility" and greater "xenobiotics biodegradation and metabolism." The findings illustrate the diverse microbial assemblages that occur on microplastic and increase our understanding of plastisphere ecology. Copyright © 2017 Elsevier B.V. All rights reserved.

Sedimentary Records of Hyperpycnal Flows and the Influence of River Damming on Sediment Dynamics of Estuaries: Examples from the Nelson, Churchill, Moisie and Sainte-Marguerite Rivers (Canada)

NASA Astrophysics Data System (ADS)

St-Onge, G.; Duboc, Q.; Boyer-Villemaire, U.; Lajeunesse, P.; Bernatchez, P.

2015-12-01

Sediment cores were sampled in the estuary of the Nelson and Churchill Rivers in western Hudson Bay, as well as in the estuary of the Moisie and Sainte-Marguerite Rivers in Gulf of St. Lawrence in order to evaluate the impact of hydroelectric dams on the sedimentary regime of these estuaries. The gravity cores at the mouth of the Nelson River recorded several cm-thick rapidly deposited layers with a reverse to normal grading sequence, indicating the occurrence of hyperpycnal flows generated by major floods during the last few centuries. These hyperpycnal flows were probably caused by ice-jam formation, which can increase both the flow and the sediment concentration following the breaching of such natural dams. Following the construction of hydroelectric dams since the 1960s, the regulation of river discharge prevented the formation of hyperpycnal flows, and hence the deposition of hyperpycnites in the upper part of the cores. In the core sampled in the estuary of the Churchill River, only one hyperpycnite was recorded. This lower frequency may be due to the enclosed estuary of the Churchill River, its weaker discharge and the more distal location of the coring site.In the Gulf of St. Lawrence, grain size measurements allowed the identification of a major flood around AD 1844±4 years in box cores from both the Sainte-Marguerite and Moisie Rivers, whereas a drastic decrease in variations in the median grain size occurred around AD ~1900 in the estuary of the Sainte-Marguerite River, highlighting the offshore impact of the SM1 dam construction in the early 1900s. Furthermore, sedimentological variations in the box cores from both estuaries have been investigated by wavelet analysis and the sharp disappearance of high frequencies around AD 1900 in the estuary of the dammed river (Sainte-Marguerite River), but not in the estuary of the natural river (Moisie River), also provides evidence of the influence of dams on the sedimentary regime of estuaries.

Spatiotemporal Distribution, Sources, and Photobleaching Imprint of Dissolved Organic Matter in the Yangtze Estuary and Its Adjacent Sea Using Fluorescence and Parallel Factor Analysis

PubMed Central

Li, Penghui; Chen, Ling; Zhang, Wen; Huang, Qinghui

2015-01-01

To investigate the seasonal and interannual dynamics of dissolved organic matter (DOM) in the Yangtze Estuary, surface and bottom water samples in the Yangtze Estuary and its adjacent sea were collected and characterized using fluorescence excitation-emission matrices (EEMs) and parallel factor analysis (PARAFAC) in both dry and wet seasons in 2012 and 2013. Two protein-like components and three humic-like components were identified. Three humic-like components decreased linearly with increasing salinity (r>0.90, p<0.001), suggesting their distribution could primarily be controlled by physical mixing. By contrast, two protein-like components fell below the theoretical mixing line, largely due to microbial degradation and removal during mixing. Higher concentrations of humic-like components found in 2012 could be attributed to higher freshwater discharge relative to 2013. There was a lack of systematic patterns for three humic-like components between seasons and years, probably due to variations of other factors such as sources and characteristics. Highest concentrations of fluorescent components, observed in estuarine turbidity maximum (ETM) region, could be attributed to sediment resuspension and subsequent release of DOM, supported by higher concentrations of fluorescent components in bottom water than in surface water at two stations where sediments probably resuspended. Meanwhile, photobleaching could be reflected from the changes in the ratios between fluorescence intensity (Fmax) of humic-like components and chromophoric DOM (CDOM) absorption coefficient (a355) along the salinity gradient. This study demonstrates the abundance and composition of DOM in estuaries are controlled not only by hydrological conditions, but also by its sources, characteristics and related estuarine biogeochemical processes. PMID:26107640

Identification of long-term trends and seasonality in high-frequency water quality data from the Yangtze River basin, China

PubMed Central

He, Bin; Chen, Yaning; Zou, Shan; Wang, Yi; Nover, Daniel; Chen, Wen; Yang, Guishan

2018-01-01

Comprehensive understanding of the long-term trends and seasonality of water quality is important for controlling water pollution. This study focuses on spatio-temporal distributions, long-term trends, and seasonality of water quality in the Yangtze River basin using a combination of the seasonal Mann-Kendall test and time-series decomposition. The used weekly water quality data were from 17 environmental stations for the period January 2004 to December 2015. Results show gradual improvement in water quality during this period in the Yangtze River basin and greater improvement in the Uppermost Yangtze River basin. The larger cities, with high GDP and population density, experienced relatively higher pollution levels due to discharge of industrial and household wastewater. There are higher pollution levels in Xiang and Gan River basins, as indicated by higher NH4-N and CODMn concentrations measured at the stations within these basins. Significant trends in water quality were identified for the 2004–2015 period. Operations of the three Gorges Reservoir (TGR) enhanced pH fluctuations and possibly attenuated CODMn, and NH4-N transportation. Finally, seasonal cycles of varying strength were detected for time-series of pollutants in river discharge. Seasonal patterns in pH indicate that maxima appear in winter, and minima in summer, with the opposite true for CODMn. Accurate understanding of long-term trends and seasonality are necessary goals of water quality monitoring system efforts and the analysis methods described here provide essential information for effectively controlling water pollution. PMID:29466354

Identification of long-term trends and seasonality in high-frequency water quality data from the Yangtze River basin, China.

PubMed

Duan, Weili; He, Bin; Chen, Yaning; Zou, Shan; Wang, Yi; Nover, Daniel; Chen, Wen; Yang, Guishan

2018-01-01

Comprehensive understanding of the long-term trends and seasonality of water quality is important for controlling water pollution. This study focuses on spatio-temporal distributions, long-term trends, and seasonality of water quality in the Yangtze River basin using a combination of the seasonal Mann-Kendall test and time-series decomposition. The used weekly water quality data were from 17 environmental stations for the period January 2004 to December 2015. Results show gradual improvement in water quality during this period in the Yangtze River basin and greater improvement in the Uppermost Yangtze River basin. The larger cities, with high GDP and population density, experienced relatively higher pollution levels due to discharge of industrial and household wastewater. There are higher pollution levels in Xiang and Gan River basins, as indicated by higher NH4-N and CODMn concentrations measured at the stations within these basins. Significant trends in water quality were identified for the 2004-2015 period. Operations of the three Gorges Reservoir (TGR) enhanced pH fluctuations and possibly attenuated CODMn, and NH4-N transportation. Finally, seasonal cycles of varying strength were detected for time-series of pollutants in river discharge. Seasonal patterns in pH indicate that maxima appear in winter, and minima in summer, with the opposite true for CODMn. Accurate understanding of long-term trends and seasonality are necessary goals of water quality monitoring system efforts and the analysis methods described here provide essential information for effectively controlling water pollution.

Polychlorinated dibenzo-p-dioxins, dibenzofurans, and dioxin-like polychlorinated biphenyls in sediments from the Yellow and Yangtze Rivers, China.

PubMed

Gao, Lirong; Huang, Huiting; Liu, Lidan; Li, Cheng; Zhou, Xin; Xia, Dan

2015-12-01

Polychlorinated dibenzodioxins and dibenzofurans (PCDD/Fs) and polychlorinated biphenyls (PCBs) are toxic environmental pollutants that are often found in sediments. The Yangtze and Yellow rivers in China are two of the largest rivers in Asia and are therefore important aquatic ecosystems; however, few studies have investigated the PCDD/F and PCB content in the sediments of these rivers. Accordingly, this study was conducted to generate baseline data for future environmental risk assessments. In the present study, 26 surface sediments from the middle reaches of the Yellow and Yangtze rivers were analyzed for PCDD/Fs and dioxin-like (dl) PCBs by high-resolution gas chromatography and high-resolution mass spectrometry. The ranges of PCDD/F, dl-PCB, and WHO-TEQ content in sediments from the Yellow River were 2.1-19.8, 1.11-9.9, and 0.08-0.57 pg/g (dry weight), respectively. The ranges of PCDD/F, dl-PCB, and WHO-TEQ content in sediments from the Yangtze River were 6.1-84.9, 1.8-24.1, and 0.13-0.29 pg/g (dry weight), respectively. Total organic carbon and dl-PCB contents in the Yellow River were significantly correlated (Spearman's correlation coefficient, r = 0.64, P < 0.05). It is well known that total organic carbon plays a role in the transport and redistribution of dl-PCB. Principal component analysis indicated that PCDD/Fs may arise from pentachlorophenol, sodium pentachlorophenate, and atmospheric deposition, while dl-PCBs likely originate from burning of coal and wood for domestic heating. The dioxin levels in the river sediments examined in this study were relatively low. These findings advance our knowledge regarding eco-toxicity and provide useful information regarding contamination sources.

Human impacts on sediment in the Yangtze River: A review and new perspectives

NASA Astrophysics Data System (ADS)

Yang, H. F.; Yang, S. L.; Xu, K. H.; Milliman, J. D.; Wang, H.; Yang, Z.; Chen, Z.; Zhang, C. Y.

2018-03-01

Changes in riverine suspended and riverbed sediments have environmental, ecological and social implications. Here, we provide a holistic review of water and sediment transport and examine the human impacts on the flux, concentration and size of sediment in the Yangtze River in recent decades. We find that most of the fluvial sediment has been trapped in reservoirs, except for the finest portion. Furthermore, soil-conservation since the 1990s has reduced sediment yield. From 1956-1968 (pre-dam period) to 2013-2015 (post-dams and soil-conservation), the sediment discharge from the sub-basins decreased by 91%; in the main river, the sediment flux decreased by 99% at Xiangjiaba (upper reach), 97% at Yichang (transition between upper and middle reaches), 83% at Hankou (middle reach), and 77% at Datong (tidal limit). Because the water discharge was minimally impacted, the suspended sediment concentration decreased to the same extent as the sediment flux. Active erosion of the riverbed and coarsening of surficial sediments were observed in the middle and lower reaches. Fining of suspended sediments was identified along the river, which was counteracted by downstream erosion. Along the 700-km-long Three Gorges Reservoir, which retained 80% of the sediment from upstream, the riverbed gravel or rock was buried by mud because of sedimentation after impoundment. Along with these temporal variations, the striking spatial patterns of riverine suspended and riverbed sediments that were previously exhibited in this large basin were destroyed or reversed. Therefore, we conclude that the human impacts on sediment in the Yangtze River are strong and systematic.

Predicting assemblages and species richness of endemic fish in the upper Yangtze River.

PubMed

He, Yongfeng; Wang, Jianwei; Lek-Ang, Sithan; Lek, Sovan

2010-09-01

The present work describes the ability of two modeling methods, Classification and Regression Tree (CART) and Random Forest (RF), to predict endemic fish assemblages and species richness in the upper Yangtze River, and then to identify the determinant environmental factors contributing to the models. The models included 24 predictor variables and 2 response variables (fish assemblage and species richness) for a total of 46 site units. The predictive quality of the modeling approaches was judged with a leave-one-out validation procedure. There was an average success of 60.9% and 71.7% to assign each site unit to the correct assemblage of fish, and 73% and 84% to explain the variance in species richness, by using CART and RF models, respectively. RF proved to be better than CART in terms of accuracy and efficiency in ecological applications. In any case, the mixed models including both land cover and river characteristic variables were more powerful than either individual one in explaining the endemic fish distribution pattern in the upper Yangtze River. For instance, altitude, slope, length, discharge, runoff, farmland and alpine and sub-alpine meadow played important roles in driving the observed endemic fish assemblage structure, while farmland, slope grassland, discharge, runoff, altitude and drainage area in explaining the observed patterns of endemic species richness. Therefore, the various effects of human activity on natural aquatic ecosystems, in particular, the flow modification of the river and the land use changes may have a considerable effect on the endemic fish distribution patterns on a regional scale. Copyright 2010 Elsevier B.V. All rights reserved.

Trends and variability of daily precipitation extremes during 1960-2012 in the Yangtze River Basin, China

USDA-ARS?s Scientific Manuscript database

Trends and variability of extreme precipitation events are important for water-related disaster prevention and mitigation as well as water resource management. Based on daily precipitation dataset from 143 meteorological stations in the Yangtze River Basin (YRB), a suite of precipitation indices rec...

Modeling the spatial-temporal dynamics of net primary production in Yangtze River Basin using IBIS model

USGS Publications Warehouse

Zhang, Z.; Jiang, H.; Liu, J.; Zhu, Q.; Wei, X.; Jiang, Z.; Zhou, G.; Zhang, X.; Han, J.

2011-01-01

The climate change has significantly affected the carbon cycling in Yangtze River Basin. To better understand the alternation pattern for the relationship between carbon cycling and climate change, the net primary production (NPP) were simulated in the study area from 1956 to 2006 by using the Integrated Biosphere Simulator (IBIS). The results showed that the average annual NPP per square meter was about 0.518 kg C in Yangtze River Basin. The high NPP levels were mainly distributed in the southeast area of Sichuan, and the highest value reached 1.05 kg C/m2. The NPP increased based on the simulated temporal trends. The spatiotemporal variability of the NPP in the vegetation types was obvious, and it was depended on the climate and soil condition. We found the drought climate was one of critical factor that impacts the alterations of the NPP in the area by the simulation. ?? 2011 IEEE.

Biogeochemical transport in the Loxahatchee River estuary, FL: The role of submarine groundwater discharge

NASA Astrophysics Data System (ADS)

Swarzenski, P.; Orem, B.; McPherson, B.; Baskaran, M.; Wan, Y.

2005-05-01

The distributions of dissolved organic carbon (DOC), silica, select trace elements (Mn, Fe, Ba, Sr, Co, V,) and a suite of naturally-occurring radionuclides in the U/Th decay series (222Rn, 223,224,226,228Ra, 238U) were studied during high and low discharge conditions in the Loxahatchee River estuary, Florida. The zero-salinity endmember of this still relatively pristine estuary may reflect not only river-borne constituents, but also those advected during active groundwater/surface-water discharge. During low discharge conditions, with the notable exception of Co, trace metals indicate nearly conservative mixing from a salinity of ~12 through the estuary (This statement contracdicts with what is said in p. 7). In contrast, of the trace metals studied, only Sr, Fe, U and V exhibited conservative estuarine mixing during high discharge. Dissolved organic carbon and Si concentrations were highest at zero salinities, and generally decreased with an increase in salinity during both discharge regimes, indicating removal of land-derived dissolved organic matter and silica in the estuary. Suspended particulate matter (SPM) concentrations were generally lowest (< 5 mg L-1) close of zero salinity, and increased several-fold (~18 mg L-1; low discharge) towards the seaward endmember and this attributed dynamic resuspension the estuary. Surface water-column 222Rn activities were most elevated (> 28 dpm L-1) at the freshwater endmember of the estuary, and appear to identify regions of the river most influenced by active submarine groundwater discharge (where is the data that show this?). Activities of four naturally-occurring isotopes of Ra (223,224,226,228Ra) in this estuary and select adjacent shallow groundwater wells indicate mean estuarine water mass residence times of less than 1 day; values in close agreement to those calculated by tidal prism and tidal period. A radium-based model for estimating submarine groundwater discharge to the Loxahatchee River estuary yielded an

Satellite remote sensing of water resources in the Yangtze and Yellow Rivers of China based on infrared imagery of cloud distributions

NASA Technical Reports Server (NTRS)

Hung, R. J.; Dodge, James C.

1990-01-01

Although the two largest rivers in China originate in the same region, separated only by the Bayanhar Mountains as a watershed, the Yangtze and Yellow Rivers behave in quite different ways. Most of the warm and humid air currents from the Arabian Sea and Bay of Bengal are blocked by the Bayanhar Mountains. As a result, the amount of water in the Yellow River is only 5 percent of that in the Yangtze River. Based on the cloud coverage area and the cloud volumetric distributions, and also the thickness above 9.4 kms of the cumulus clouds located north and south of the Bayanhar Mountains, from GEO satellite IR imagery, the results suggest that a more detailed investigation is warranted in the hope that the proper modification of cumuli north of the Bayanhar Mountains would enhance the rainfall over the fountainhead of the Yellow River.

Variation of River Islands around a Large City along the Yangtze River from Satellite Remote Sensing Images

PubMed Central

Shi, Haiyun; Gao, Chao; Dong, Changming; Xia, Changshui; Xu, Guanglai

2017-01-01

River islands are sandbars formed by scouring and silting. Their evolution is affected by several factors, among which are runoff and sediment discharge. The spatial-temporal evolution of seven river islands in the Nanjing Section of the Yangtze River of China was examined using TM (Thematic Mapper) and ETM (Enhanced Thematic Mapper)+ images from 1985 to 2015 at five year intervals. The following approaches were applied in this study: the threshold value method, binarization model, image registration, image cropping, convolution and cluster analysis. Annual runoff and sediment discharge data as measured at the Datong hydrological station upstream of Nanjing section were also used to determine the roles and impacts of various factors. The results indicated that: (1) TM/ETM+ images met the criteria of information extraction of river islands; (2) generally, the total area of these islands in this section and their changing rate decreased over time; (3) sediment and river discharge were the most significant factors in island evolution. They directly affect river islands through silting or erosion. Additionally, anthropocentric influences could play increasingly important roles. PMID:28953218

Comparison of common persistent organic pollutants (POPs) in flounder (Platichthys flesus) from the Vistula (Poland) and Douro (Portugal) River estuaries.

PubMed

Waszak, Ilona; Dabrowska, Henryka; Komar-Szymczak, Katarzyna

2014-04-15

Groups of flounder (Platichthys flesus) females were collected in 2011 from the Vistula River and the Duoro River estuaries and corresponding reference sites in the southern Baltic Sea and Portuguese coast of the Atlantic Ocean to measure and compare the levels and profiles of polychlorinated biphenyls (PCBs), organochlorine pesticides (OCPs), and polybrominated diphenyl ethers (PBDEs). The estuaries' sediments were also investigated. Several differences were found in the POPs between the estuaries and between the two marine regions, which were highlighted by PCA. The Vistula River estuary POPs, significantly higher than in the Douro River estuary, were dominated by DDTs followed by PCBs. PBDEs levels, indifferent between the estuaries, were relatively low. The POP levels in flounder and sediment evaluated against environmental assessment criteria (EACs) indicated that none of the measured contaminants for which EAC had been established exceeded the criterion, except for CB-118 in flounder from the Vistula River estuary. Copyright © 2014 Elsevier Ltd. All rights reserved.

Phosphorus sorption and buffering mechanisms in suspended sediments from the Yangtze Estuary and Hangzhou Bay, China

NASA Astrophysics Data System (ADS)

Li, M.; Whelan, M. J.; Wang, G.; White, S. M.

2012-12-01

The adsorption isotherm and the mechanism of the buffering effect are important controls on phosphorus behaviors in estuaries and are important for estimating phosphate concentrations in aquatic environments. In this paper, we derive phosphate adsorption isotherms in order to investigate sediment adsorption and buffering capacity for phosphorus discharged from sewage outfalls in the Yangtze Estuary and Hangzhou Bay near Shanghai, China. Experiments were also carried out at different temperatures in order to explore the buffering effects for phosphate. The results show that P sorption in sediments with low fine particle fractions was best described using exponential equations. Some P interactions between water and sediment may be caused by the precipitation of CaHPO4 from Ca2+ and HPO42- when the phosphate concentration in the liquid phase is high. Results from the buffering experiments suggest that the Zero Equilibrium Phosphate Concentrations (EPC0) vary from 0.014 mg l-1 to 0.061 mg l-1, which are consistent with measured phosphate concentrations in water samples collected at the same time as sediment sampling. Values of EPC0 and linear sorption coefficients (K) in sediments with high fine particle and organic matter contents are relatively high, which implies that they have high buffering capacity. Both EPC0 and K increase with increasing temperature, indicating a higher P buffering capacity at high temperatures.

Phosphorus sorption and buffering mechanisms in suspended sediments from the Yangtze Estuary and Hangzhou Bay, China

NASA Astrophysics Data System (ADS)

Li, M.; Whelan, M. J.; Wang, G. Q.; White, S. M.

2013-05-01

The adsorption isotherm and the mechanism of the buffering effect are important controls on phosphorus (P) behaviors in estuaries and are important for estimating phosphate concentrations in aquatic environments. In this paper, we derive phosphate adsorption isotherms in order to investigate sediment adsorption and buffering capacity for phosphorus discharged from sewage outfalls in the Yangtze Estuary and Hangzhou Bay near Shanghai, China. Experiments were also carried out at different temperatures in order to explore the buffering effects for phosphate. The results show that P sorption in sediments with low fine particle fractions was best described using exponential equations. Some P interactions between water and sediment may be caused by the precipitation of CaHPO4 from Ca2+ and HPO42- when the phosphate concentration in the liquid phase is high. Results from the buffering experiments suggest that the Zero Equilibrium Phosphate Concentrations (EPC0) vary from 0.014 mg L-1 to 0.061 mg L-1, which are consistent with measured phosphate concentrations in water samples collected at the same time as sediment sampling. Values of EPC0 and linear sorption coefficients (K) in sediments with high fine particle and organic matter contents are relatively high, which implies that they have high buffering capacity. Both EPC0 and K increase with increasing temperature, indicating a higher P buffering capacity at high temperatures.

Rhenium Concentration Variations in the Non-flood Period of the Yangtze River Water and Estimation of the Oxidation Rate of Organic Carbon

NASA Astrophysics Data System (ADS)

Xu, P.; Chen, Y.; Li, S.; Wang, K.

2017-12-01

In geological history, the uplift of the Tibet plateau has accelerated the silicate weathering and organic carbon burial at the same time, which made great influence on the global carbon cycle by increasing the carbon sink. Because of the vital connection between tectonic uplift and carbon cycle, more and more attention was casted on rivers originating from orogens. The Yangtze River, as an important large river in the world, is one of them. However, although silicate weathering has been studied thoroughly, researches on organic carbon cycle are much less, and oxidation of fossil organic carbon remained poorly constrained. In this study, we try to use rhenium(Re) as a proxy to estimate the oxidation rate of fossil organic carbon and thus proceed our understanding towards the carbon cycle, the silicate weathering. This is because Re has a close relationship with organic carbon in the sediments and will be released into hydrological network in the mountain river catchments by being oxidized and exist as soluble ReO4-, so that we can use Re concentration in river water to estimate the oxidation rate of organic carbon. We collected water samples from the Yangtze River fortnightly at Banqiao Ferry and the sampling date cover the non-flood period. In this way, we are able to have a rough estimate of the amount of carbon dioxide that released to the atmosphere by the oxidation of organic carbon, using the data of non-flood period we got. We found that Re concentration in Yangtze River ranges approximately from 45 to 85 pmol/L. The rate of organic carbon weathering is estimated using the expression, ΦCO2,fossil=[Re]×runoff×[OC/Re]rock, and according to researches on the black shale of Yangtze River, the value 2.86×106 is chosen as the ratio OC(organic carbon) to Re in the black shale. The result is a really high flux, up to 152×109mol/y, just a little less than of the CO2 consumption rates from silicate weathering which is 191×109mol/y and about 166×109mol/y in non

Polycyclic aromatic hydrocarbons in surface sediment of typical estuaries and the spatial distribution in Haihe river basin.

PubMed

Liu, Jing L; Zhang, Jing; Liu, Feng; Zhang, Lu L

2014-05-01

Polycyclic aromatic hydrocarbons (PAHs) with carcinogenic and mutagenic characteristics have been detected in many estuaries and bays around the world. To detect the contaminated level in typical estuaries in Haihe river basin, China, a comprehensive survey of 16 PAHs in surface sediment has been conducted and an ecological risk assessment has been taken. It showed that Haihe river estuary had the highest concentration, ranging from 92.91 to 15886.00 ng g(-1). And Luan river estuary has the lowest polluted level, ranging from 39.55 to 328.10 ng g(-1). PAHs in sediment were dominated by low and mid molecular weight PAHs in all the sampling sites. Most of the sampling sites in all sampling seasons indicated a rarely happened ecological risk of ΣPAHs, while the S6 in Haihe river estuary was in an occasionally anticipated risk. To illustrate the spatial distribution pattern of PAHs in surface sediment in Haihe river basin, the results were compared with previous research of the research team. Based on data of the comparison, it had been revealed that Haihe river had the most serious PAHs pollution, with an average concentration of 5884.86 ng g(-1), and showed the highest contamination level in all four ecological units. The ΣPAHs concentration showed in a rank of reservoir > estuary > rural area > city.

Optimization of sample preparation and chromatography for the determination of perfluoroalkyl acids in sediments from the Yangtze Estuary and East China Sea.

PubMed

Wang, Qian-Wen; Yang, Gui-Peng; Zhang, Ze-Ming; Zhang, Jing

2018-08-01

Perfluoroalkyl acids (PFAAs) are ubiquitous pollutants present in various environmental media, including marine sediments. A method was proposed for the determination of 17 target PFAA analytes in marine sediment samples (n = 49) collected from the Yangtze Estuary and East China Sea. The proposed method involves the use of an optimized pretreatment procedure and ultrahigh-performance liquid chromatography electrospray ionization-tandem mass spectrometry in dynamic multiple reaction monitoring mode. The method relied on extraction cycles using methanol followed by concentration, filtration, and small volume injection to UHPLC-MS/MS. The recovery, time efficiency, and detection limit of the proposed method are improved relative to those of traditional methods. Limits of detection varied from 0.003 to 0.045 ng/g, and spike recoveries to sediment ranged from 90% to 110% with suitable precisions (1.7%-14.6%). PFAAs were widely present in the samples, and ΣPFAAs ranged from 0.67 ng/g dw to 36.75 ng/g dw. Results indicated that terrigenous input strongly influences PFAA distribution in sediments from the study areas. Perfluorooctanoic acid (PFOA) and perfluorooctanesulfonate (PFOS) were identified as the dominant perfluorocarboxylic acid (PFCA) and perfluoroalkylsulfonate (PFSA) in sediment samples from the Yangtze Estuary and the East China Sea. Preliminary environmental risk assessment indicated that PFOS may pose a higher environmental risk than PFOA. Furthermore, risk quotient values indicated that PFOS poses a significant risk to the aquatic ecosystem of the study areas. Copyright © 2018 Elsevier Ltd. All rights reserved.

Estimating sediment budgets at the interface between rivers and estuaries with application to the Sacramento-San Joaquin River Delta

USGS Publications Warehouse

Wright, S.A.; Schoellhamer, D.H.

2005-01-01

[1] Where rivers encounter estuaries, a transition zone develops where riverine and tidal processes both affect sediment transport processes. One such transition zone is the Sacramento-San Joaquin River Delta, a large, complex system where several rivers meet to form an estuary (San Francisco Bay). Herein we present the results of a detailed sediment budget for this river/estuary transitional system. The primary regional goal of the study was to measure sediment transport rates and pathways in the delta in support of ecosystem restoration efforts. In addition to achieving this regional goal, the study has produced general methods to collect, edit, and analyze (including error analysis) sediment transport data at the interface of rivers and estuaries. Estimating sediment budgets for these systems is difficult because of the mixed nature of riverine versus tidal transport processes, the different timescales of transport in fluvial and tidal environments, and the sheer complexity and size of systems such as the Sacramento-San Joaquin River Delta. Sediment budgets also require error estimates in order to assess whether differences in inflows and outflows, which could be small compared to overall fluxes, are indeed distinguishable from zero. Over the 4 year period of this study, water years 1999-2002, 6.6 ?? 0.9 Mt of sediment entered the delta and 2.2 ?? 0.7 Mt exited, resulting in 4.4 ?? 1.1 Mt (67 ?? 17%) of deposition. The estimated deposition rate corresponding to this mass of sediment compares favorably with measured inorganic sediment accumulation on vegetated wetlands in the delta.

Low-angle dunes in the Changjiang (Yangtze) Estuary: Flow and sediment dynamics under tidal influence

NASA Astrophysics Data System (ADS)

Hu, Hao; Wei, Taoyuan; Yang, Zhongyong; Hackney, Christopher R.; Parsons, Daniel R.

2018-05-01

It has long been highlighted that important feedbacks exist between river bed morphology, sediment transport and the turbulent flow field and that these feedbacks change in response to forcing mechanisms. However, our current understanding of bedform dynamics is largely based on studies of steady flow environments and cohesionless bed conditions. Few investigations have been made under rapidly changing flows. Here, we examine flow and sediment dynamics over low-angle dunes in unsteady flows in the Changjiang (Yangtze) Estuary, China. Topography, flow and sediment data were collected over a reach ca 1.8 km long through a semi-diurnal tidal cycle in a moderate tide of flood season. The results show that: (1) roughness length derived from the upper flow changes little with the flow reversing and displays the same value on both the ebb and flood tide. Moreover, the variability of individual bedform features plays an important role in roughness length variation. (2) Shear stress over the crest of low-angle dunes roughly represents the total spatially averaged stress over dunes in this study area, which has significant implications for advancing numerical models. (3) Changes in morphology, flow and sediment dynamics over dunes through time reveal how low-angle dunes evolve within a tidal cycle. (4) The clockwise hysteresis loops between flow dynamics and bedform features (height and aspect ratio) are also observed. The combination of suspended sediment transport and bedload transport on dune transformation and migration attributes to the clockwise hysteresis. The specific sediment composition of the riverbed, in some extent, affects the mechanism of sediment transport related to the exchange between suspended sediment and riverbed, but further investigation is needed to figure out the mechanism behind this for extended series of tides, such as spring/neap tide and tides in flooding and dry season.

Zooplankton community analysis in the Changjiang River estuary by single-gene-targeted metagenomics

NASA Astrophysics Data System (ADS)

Cheng, Fangping; Wang, Minxiao; Li, Chaolun; Sun, Song

2014-07-01

DNA barcoding provides accurate identification of zooplankton species through all life stages. Single-gene-targeted metagenomic analysis based on DNA barcode databases can facilitate longterm monitoring of zooplankton communities. With the help of the available zooplankton databases, the zooplankton community of the Changjiang (Yangtze) River estuary was studied using a single-gene-targeted metagenomic method to estimate the species richness of this community. A total of 856 mitochondrial cytochrome oxidase subunit 1 (cox1) gene sequences were determined. The environmental barcodes were clustered into 70 molecular operational taxonomic units (MOTUs). Forty-two MOTUs matched barcoded marine organisms with more than 90% similarity and were assigned to either the species (similarity>96%) or genus level (similarity<96%). Sibling species could also be distinguished. Many species that were overlooked by morphological methods were identified by molecular methods, especially gelatinous zooplankton and merozooplankton that were likely sampled at different life history phases. Zooplankton community structures differed significantly among all of the samples. The MOTU spatial distributions were influenced by the ecological habits of the corresponding species. In conclusion, single-gene-targeted metagenomic analysis is a useful tool for zooplankton studies, with which specimens from all life history stages can be identified quickly and effectively with a comprehensive database.

[Sagittal otolith morphology and the relationship between its mass and the age of Liza haematocheila in the Yangtze Estuary, China].

PubMed

Ji, Yan; Zhao, Feng; Yang, Qin; Ma, Rong Rong; Yang, Gang; Zhang, Tao; Zhuang, Ping

2018-03-01

To examine the relationship of morphological characters of sagittal otolith and the age of Liza haematocheila in the Yangtze Estuary, we analyzed the morphological parameters of 324 pairs of otoliths extracted from 358 L. haematocheila specimens from the Yangtze Estuary in February to June of 2017. The results showed that sagittal otolith had rostrum, antirostrum and obvious central notch. The size and shape of sagittal otolith significantly changed with their growth, from regular melon seeds shape outline to long narrow leaf shape and increasing irregular wavy outline. The average density of sagittal otolith was 1.52 mg·mm -2 . The average rectangularity was 0.68. The length of sagittal otolith was 0.021%-0.047% of entire body length (BL), the width was 0.009%-0.021% of entire BL, and the mass was 0.045‰-0.731‰ of the entire body mass (BM). Otolith length (OL), otolith width (OW) and otolith mass (OM) were all significantly related to the BL, with the determination coefficient for OW and OM model being the highest (R 2 =0.928). The relationship between OM and BL was described best by exponential regression: OM=0.0009BL 1.8737 (R 2 =0.967). The relationships between OM and age (A), BL and A were well fitted by multinomial regressions, respectively: OM=2.9262A 2 +4.8437A+2.1894 (R 2 =0.847), BL=-3.2248A 2 +102.54A+38.373 (R 2 =0.858). In addition, OM was linearly correlated with A. The estimated otolith's ages from the model did not significantly variate from the real ages counting from annulus counts. Therefore, OM could be an effective parameter for the age estimation of L. haematocheila.

Coastal Upwelling Supplies Oxygen-Depleted Water to the Columbia River Estuary

PubMed Central

Roegner, G. Curtis; Needoba, Joseph A.; Baptista, António M.

2011-01-01

Low dissolved oxygen (DO) is a common feature of many estuarine and shallow-water environments, and is often attributed to anthropogenic nutrient enrichment from terrestrial-fluvial pathways. However, recent events in the U.S. Pacific Northwest have highlighted that wind-forced upwelling can cause naturally occurring low DO water to move onto the continental shelf, leading to mortalities of benthic fish and invertebrates. Coastal estuaries in the Pacific Northwest are strongly linked to ocean forcings, and here we report observations on the spatial and temporal patterns of oxygen concentration in the Columbia River estuary. Hydrographic measurements were made from transect (spatial survey) or anchor station (temporal survey) deployments over a variety of wind stresses and tidal states during the upwelling seasons of 2006 through 2008. During this period, biologically stressful levels of dissolved oxygen were observed to enter the Columbia River estuary from oceanic sources, with minimum values close to the hypoxic threshold of 2.0 mg L−1. Riverine water was consistently normoxic. Upwelling wind stress controlled the timing and magnitude of low DO events, while tidal-modulated estuarine circulation patterns influenced the spatial extent and duration of exposure to low DO water. Strong upwelling during neap tides produced the largest impact on the estuary. The observed oxygen concentrations likely had deleterious behavioral and physiological consequences for migrating juvenile salmon and benthic crabs. Based on a wind-forced supply mechanism, low DO events are probably common to the Columbia River and other regional estuaries and if conditions on the shelf deteriorate further, as observations and models predict, Pacific Northwest estuarine habitats could experience a decrease in environmental quality. PMID:21533083

Genetic diversity of the Chinese goat in the littoral zone of the Yangtze River as assessed by microsatellite and mtDNA.

PubMed

E, Guang-Xin; Zhao, Yong-Ju; Chen, Li-Peng; Ma, Yue-Hui; Chu, Ming-Xing; Li, Xiang-Long; Hong, Qiong-Hua; Li, Lan-Hui; Guo, Ji-Jun; Zhu, Lan; Han, Yan-Guo; Gao, Hui-Jiang; Zhang, Jia-Hua; Jiang, Huai-Zhi; Jiang, Cao-De; Wang, Gao-Fu; Ren, Hang-Xing; Jin, Mei-Lan; Sun, Yuan-Zhi; Zhou, Peng; Huang, Yong-Fu

2018-05-01

The objective of this study was to assess the genetic diversity and population structure of goats in the Yangtze River region using microsatellite and mtDNA to better understand the current status of those goat genetic diversity and the effects of natural landscape in fashion of domestic animal genetic diversity. The genetic variability of 16 goat populations in the littoral zone of the Yangtze River was estimated using 21 autosomal microsatellites, which revealed high diversity and genetic population clustering with a dispersed geographical distribution. A phylogenetic analysis of the mitochondrial D-loop region (482 bp) was conducted in 494 goats from the Yangtze River region. In total, 117 SNPs were reconstructed, and 173 haplotypes were identified, 94.5% of which belonged to lineages A and B. Lineages C, D, and G had lower frequencies (5.2%), and lineage F haplotypes were undetected. Several high-frequency haplotypes were shared by different ecogeographically distributed populations, and the close phylogenetic relationships among certain low-frequency haplotypes indicated the historical exchange of genetic material among these populations. In particular, the lineage G haplotype suggests that some west Asian goat genetic material may have been transferred to China via Muslim migration.

Urban Household Carbon Emission and Contributing Factors in the Yangtze River Delta, China

PubMed Central

Xu, Xibao; Tan, Yan; Chen, Shuang; Yang, Guishan; Su, Weizhong

2015-01-01

Carbon reduction at the household level is an integral part of carbon mitigation. This study analyses the characteristics, effects, contributing factors and policies for urban household carbon emissions in the Yangtze River Delta of China. Primary data was collected through structured questionnaire surveys in three cities in the region – Nanjing, Ningbo, and Changzhou in 2011. The survey data was first used to estimate the magnitude of household carbon emissions in different urban contexts. It then examined how, and to what extent, each set of demographic, economic, behavioral/cognitive and spatial factors influence carbon emissions at the household level. The average of urban household carbon emissions in the region was estimated to be 5.96 tonnes CO2 in 2010. Energy consumption, daily commuting, garbage disposal and long-distance travel accounted for 51.2%, 21.3%, 16.0% and 11.5% of the total emission, respectively. Regulating rapidly growing car-holdings of urban households, stabilizing population growth, and transiting residents’ low-carbon awareness to household behavior in energy saving and other spheres of consumption in the context of rapid population aging and the growing middle income class are suggested as critical measures for carbon mitigation among urban households in the Yangtze River Delta. PMID:25884853

Modal analysis of annual runoff volume and sediment load in the Yangtze river-lake system for the period 1956-2013.

PubMed

Chen, Huai; Zhu, Lijun; Wang, Jianzhong; Fan, Hongxia; Wang, Zhihuan

2017-07-01

This study focuses on detecting trends in annual runoff volume and sediment load in the Yangtze river-lake system. Times series of annual runoff volume and sediment load at 19 hydrological gauging stations for the period 1956-2013 were collected. Based on the Mann-Kendall test at the 1% significance level, annual sediment loads in the Yangtze River, the Dongting Lake and the Poyang Lake were detected with significantly descending trends. The power spectrum estimation indicated predominant oscillations with periods of 8 and 20 years are embedded in the runoff volume series, probably related to the El Niño Southern Oscillation (2-7 years) and Pacific Decadal Oscillation (20-30 years). Based on dominant components (capturing more than roughly 90% total energy) extracted by the proper orthogonal decomposition method, total change ratios of runoff volume and sediment load during the last 58 years were evaluated. For sediment load, the mean CRT value in the Yangtze River is about -65%, and those in the Dongting Lake and the Poyang Lake are -92.2% and -87.9% respectively. Particularly, the CRT value of the sediment load in the channel inflow of the Dongting Lake is even -99.7%. The Three Gorges Dam has intercepted a large amount of sediment load and decreased the sediment load downstream.

Digital flow model of the Chowan River estuary, North Carolina

USGS Publications Warehouse

Daniel, C.C.

1977-01-01

A one-dimensional deterministic flow model based on the continuity equation had been developed to provide estimates of daily flow past a number of points on the Chowan River estuary of northeast North Carolina. The digital model, programmed in Fortran IV, computes daily average discharge for nine sites; four of these represent inflow at the mouths of major tributaries, the five other sites are at stage stations along the estuary. Because flows within the Chowan River and the lower reaches of its tributaries are tidally affected, flows occur in both upstream and downstream directions. The period of record generated by the model extends from April 1, 1974, to March 31, 1976. During the two years of model operation the average discharge at Edenhouse near the mouth of the estuary was 5,830 cfs (cubic feet per second). Daily average flows during this period ranged from 55,900 cfs in the downstream direction on July 17, 1975, to 14,200 cfs in the upstream direction on November 30, 1974

Biogeochemical transport in the Loxahatchee River estuary, Florida: The role of submarine groundwater discharge

USGS Publications Warehouse

Swarzenski, P.W.; Orem, W.H.; McPherson, B.F.; Baskaran, M.; Wan, Y.

2006-01-01

The distributions of dissolved organic carbon (DOC), Ba, U, and a suite of naturally occurring radionuclides in the U/Th decay series (222Rn, 223,224,226,228Ra) were studied during high- and low-discharge conditions in the Loxahatchee River estuary, Florida to examine the role of submarine groundwater discharge in estuarine transport. The fresh water endmember of this still relatively pristine estuary may reflect not only river-borne constituents, but also those advected during active groundwater/surface water (hyporheic) exchange. During both discharge conditions, Ba concentrations indicated slight non-conservative mixing. Such Ba excesses could be attributed either to submarine groundwater discharge or particle desorption processes. Estuarine dissolved organic carbon concentrations were highest at salinities closest to zero. Uranium distributions were lowest in the fresh water sites and mixed mostly conservatively with an increase in salinity. Suspended particulate matter (SPM) concentrations were generally lowest ( 28??dpm L- 1) at the freshwater endmember of the estuary and appear to identify regions of the river most influenced by the discharge of fresh groundwater. Activities of four naturally occurring isotopes of Ra (223,224,226,228Ra) in this estuary and select adjacent shallow groundwater wells yield mean estuarine water-mass transit times of less than 1 day; these values are in close agreement to those calculated by tidal prism and tidal frequency. Submarine groundwater discharge rates to the Loxahatchee River estuary were calculated using a tidal prism approach, an excess 226Ra mass balance, and an electromagnetic seepage meter. Average SGD rates ranged from 1.0 to 3.8 ?? 105??m3 d- 1 (20-74??L m- 2 d- 1), depending on river-discharge stage. Such calculated SGD estimates, which must include both a recirculated as well as fresh water component, are in close agreement with results obtained from a first-order watershed mass balance. Average submarine

Characterizing hydrological activities over Yangtze River basin using the new HUST-Grace2016 model, MODIS, and NCEP/NCAR data

NASA Astrophysics Data System (ADS)

Zhou, H.; Luo, Z.; Tangdamrongsub, N.; He, L.

2017-12-01

Accurate TWS estimation is important to evaluate the situation of the water resource over the Yangtze River basin. This study exploits the TWS observation from the new gravity model, HUST-Grace06, which is developed by a new low-frequency noise processing strategy. A novel GRACE post-processing approach is proposed to enhance the quality of the TWS estimate, and the improved TWS is used to characterize the hydrological activities over the Yangtze River basin. The approach includes the effective noise reduction and the leakage error mitigation based on forward modeling. The HUST-Grace06 derived TWS presents good agreement with the CSR mascon solution as well as the PCR-GLOBWB hydrological model. Particularly, our solution provides remarkable performance in identifying the extreme climate events e.g., flood and drought over the Yangtze River basin. In addition, for the first time, the NCEP/NCAR reanalysis data is incorporated with GRACE in the exploration of the climate induced hydrological activities. The comparison between GRACE and the MODIS-derived NDVI data is also conducted to investigate their connection regarding temporal and spatial distribution. The analysis suggests that the terrestrial reflectance data can be used to represent the TWS information. Importantly, such information can be used to fill the missing data in case of the early termination of GRACE or during the prelaunch of the GRACE Follow-On mission.

Larval fish distribution in the St. Louis River estuary

EPA Science Inventory

Our objective was to determine what study design, environmental, and habitat variables contribute to the distribution and abundance of larval fish in the St. Louis River estuary. Larval fish habitat associations are poorly understood in Great Lakes coastal wetlands, yet critical ...

The physical and geochemical interaction between a tidally-dominated estuary system (Wassaw Sound, GA) and a river-dominated estuary (Savannah River, GA) through salinity and inorganic carbon

Treesearch

Mike Scaboo; Christopher Hintz

2016-01-01

The Wilmington, Bull, and Savannah Rivers are interconnected waterways that flow through adjacent Savannah and Wassaw Sound Estuaries. These systems are linked by the upper reaches of the Wilmington River maintained as part of the Intracoastal Waterway. Significant changes to the Savannah River began in December 2014 with the initiation of the Savannah Harbor Expansion...

76 FR 70480 - Otay River Estuary Restoration Project, South San Diego Bay Unit of the San Diego Bay National...

Federal Register 2010, 2011, 2012, 2013, 2014

2011-11-14

... River Estuary Restoration Project, South San Diego Bay Unit of the San Diego Bay National Wildlife...), intend to prepare an environmental impact statement (EIS) for the proposed Otay River Estuary Restoration... any one of the following methods. Email: [email protected] . Please include ``Otay Estuary NOI'' in the...

Circulation and physical processes within the San Gabriel River Estuary during summer 2005

USGS Publications Warehouse

Rosenberger, Kurt J.; Xu, Jingping; Stein, Eric D.; Noble, Marlene A.; Gartner, Anne L.

2007-01-01

The Southern California Coastal Water Research Project (SCCWRP) is developing a hydrodynamic model of the SGR estuary, which is part of the comprehensive water-quality model of the SGR estuary and watershed investigated by SCCWRP and other local agencies. The hydrodynamic model will help understanding of 1) the exchange processes between the estuary and coastal ocean; 2) the circulation patterns in the estuary; 3) upstream natural runoff and the cooling discharge from PGS. Like all models, the SGR hydrodynamic model is only useful after it is fully calibrated and validated. In May 2005, SCCWRP requested the assistance of the U.S. geological Survey (USGS) Coastal and Marine Geology team (CMG) in collecting data on the hydrodynamic conditions in the estuary during the summer dry season. The summer was chosen for field data collection as this was assumed to be the season with the greatest potential for chronic degraded water quality due to low river flow and high thermal stratification within the estuary (due to both higher average air temperature and PGS output). Water quality can be degraded in winter as well, when higher river discharge events bring large volumes of water from the Los Angeles basin into the estuary. The objectives of this project were to 1) collect hydrodynamic data along the SGR estuary; 2) study exchange processes within the estuary through analysis of the hydrodynamic data; and 3) provide field data for model calibration and validation. As the data only exist for the summer season, the results herein only apply to summer conditions.

Pollution levels and risks of polycyclic aromatic hydrocarbons in surface sediments from two typical estuaries in China.

PubMed

Wang, Chenglong; Zou, Xinqing; Li, Yali; Zhao, Yifei; Song, Qiaochu; Yu, Wenwen

2017-01-30

To assess the environmental risks of polycyclic aromatic hydrocarbons (PAHs), 48 and 45 sediments were collected from the Yangtze River Estuary (YRE) and Pearl River Estuary (PRE), respectively. The toxicity equivalency concentration (TEQ) in the YRE and PRE were ranged from 1.68 to 76.13 and 9.28 to 129.24ngTEQg -1 , respectively. Results of risk quotient suggest that ecological risks of two estuaries are at a moderate level, but are higher in the PRE than YRE. The increment lifetime cancer risks (ILCR) from the YRE via ingestion and dermal contact were 1×10 -6 to 5.6×10 -5 and 4×10 -6 to 1.6×10 -4 , and ranged from 7×10 -6 to 9.4×10 -5 and 2×10 -5 to 2.8×10 -4 in the PRE. ILCR results suggest that some low and moderate cancer risk exists in the YRE and PRE. Therefore, monitoring and control measures should be carried out immediately to reduce or eliminate the risks to human health from environmental exposure. Copyright © 2016 Elsevier Ltd. All rights reserved.

Removal of Cu, Zn, Pb, and Cr from Yangtze Estuary Using the Phragmites australis Artificial Floating Wetlands

PubMed Central

Zhao, Feng; Yu, Gao; Song, Chao; Geng, Zhi

2017-01-01

Contamination of heavy metals would threaten the water and soil resources; phytoremediation can be potentially used to remediate metal contaminated sites. We constructed the Phragmites australis artificial floating wetlands outside the Qingcaosha Reservoir in the Yangtze Estuary. Water characteristic variables were measured in situ by using YSI Professional Pro Meter. Four heavy metals (copper, zinc, lead, and chromium) in both water and plant tissues were determined. Four heavy metals in estuary water were as follows: 0.03 mg/Kg, 0.016 mg/Kg, 0.0015 mg/Kg, and 0.004 mg/Kg. These heavy metals were largely retained in the belowground tissues of P. australis. The bioaccumulation (BAF) and translation factor (TF) value of four heavy metals were affected by the salinity, temperature, and dissolved oxygen. The highest BAF of each metal calculated was as follows: Cr (0.091 in winter) > Cu (0.054 in autumn) > Pb (0.016 in summer) > Zn (0.011 in summer). Highest root-rhizome TF values were recorded for four metals: 6.450 for Cu in autumn, 2.895 for Zn in summer, 7.031 for Pb in autumn, and 2.012 for Cr in autumn. This indicates that the P. australis AFW has potential to be used to protect the water of Qingcaosha Reservoir from heavy metal contamination. PMID:28717650

78 FR 1246 - Otay River Estuary Restoration Project; South San Diego Bay Unit and Sweetwater Marsh Unit of the...

Federal Register 2010, 2011, 2012, 2013, 2014

2013-01-08

...-FF08RSDC00] Otay River Estuary Restoration Project; South San Diego Bay Unit and Sweetwater Marsh Unit of the... scoping with regard to the environmental impact statement (EIS) for the proposed Otay River Estuary... one of the following methods. Email: [email protected] . Please include ``Otay Estuary NOI'' in the...

Will river erosion below the Three Gorges Dam stop in the middle Yangtze?

NASA Astrophysics Data System (ADS)

Lai, X.; Yin, D.; Finlayson, B. L.; Wei, T.; Li, M.; Yuan, W.; Yang, S.; Dai, Z.; Gao, S.; Chen, Z.

2017-11-01

The environmental impact of the Three Gorges Dam has been a subject of vigorous academic, political and social debate since its inception. This includes the key issue of post-dam river channel erosion, which was predicted by the feasibility study to extend to the river mouth. In this paper we examine the geomorphic response of the channel of the middle Yangtze for 660 km downstream of the dam. Using data on channel characteristics, bed material and sediment transport, we show that in the decade following the dam closure, pre-dam seasonal erosion has been replaced by year-round erosion, a pattern most marked at the upstream end of the study area. The sediment carrying capacity of the river channel has been largely reduced below the dam. The locus of bed scour has moved progressively downstream, ceasing as the bed material became too coarse to be transported (e.g. D50: 0.29 mm pre-dam coarsened to 20 mm below the dam by 2008). About 400 km below the dam there is a reduction in channel slope that changes the sediment carrying capacity from 0.25 kg m-3 to only about 0.05 kg m-3, which is insufficient to move bed sediment. The new long-term hydro-morphological equilibrium that will be established in this section of the middle Yangtze will prevent the further incision downstream initiated by the Three Gorges Dam. The results suggest that the full extent of adverse environmental impact predicted by the pre-dam studies will not eventuate.

Spatial dynamics of biogeochemical processes in the St. Louis River freshwater estuary

EPA Science Inventory

In the Great Lakes, river-lake transition zones within freshwater estuaries are hydrologically and biogeochemically dynamic areas that regulate nutrient and energy fluxes between rivers and Great Lakes. The goal of our study was to characterize the biogeochemical properties of th...

The asymmetric response of Yangtze river basin summer rainfall to El Niño/La Niña

NASA Astrophysics Data System (ADS)

Hardiman, Steven C.; Dunstone, Nick J.; Scaife, Adam A.; Bett, Philip E.; Li, Chaofan; Lu, Bo; Ren, Hong-Li; Smith, Doug M.; Stephan, Claudia C.

2018-02-01

The Yangtze river basin, in South East China, experiences anomalously high precipitation in summers following El Niño. This can lead to extensive flooding and loss of life. However, the response following La Niña has not been well documented. In this study, the response of Yangtze summer rainfall to El Niño/La Niña is found to be asymmetric, with no significant response following La Niña. The nature of this asymmetric response is found to be in good agreement with that simulated by the Met Office seasonal forecast system. Yangtze summer rainfall correlates positively with spring sea surface temperatures in the Indian Ocean and northwest Pacific. Indian Ocean sea surface temperatures are found to respond linearly to El Niño/La Niña, and to have a linear impact on Yangtze summer rainfall. However, northwest Pacific sea surface temperatures respond much more strongly following El Niño and, further, correlate more strongly with positive rainfall years. It is concluded that, whilst delayed Indian Ocean signals may influence summer Yangtze rainfall, it is likely that they do not lead to the asymmetric nature of the rainfall response to El Niño/La Niña.

Nutrient input from the Loxahatchee River Environmental Control District sewage-treatment plant to the Loxahatchee River Estuary, southeastern Florida

USGS Publications Warehouse

Sonntag, W.H.; McPherson, B.F.

1984-01-01

Two test discharges of treated-sewage effluent were made to the Loxahatchee River in February and September 1981 from the ENCON sewage-treatment plant to document nutrient loading and downstream transport of the effluent to the estuary under maximum daily discharge allowable by law (4 million gallons per day). Concentrations of total nitrogen in the effluent exceeded background concentrations by as much as 7 times during the February test, while concentrations of total phosphorus exceeded background concentrations by as much as 112 times during the September test. The effluent was transported downstream to the estuary in less than 24 hours. Discharge of treated sewage effluent to the river-estuary system in the 1981 water year accounted for less than 0.5 percent of the total nitrogen and 8 percent of the total phosphorus discharged from the major tributaries to the estuary. If maximum discharges of effluent (4 million gallons per day) were sustained throughout the year, annual nitrogen loading from the effluent would account for 5 to 18 percent of the total nitrogen input by the major tributaries to the estuary. With maximum discharges of effluent, annual phosphorus loading would exceed the amount of phosphorus input by the major tributaries to the estuary by 54 to 167 percent. (USGS)

Investigating Typhoon Induced River-Surge Interactions in the Tamsui Estuary, Taiwan.

NASA Astrophysics Data System (ADS)

Maskell; J. H.; Grieser, J.; Rodney, J.; Howe, N. J.

2016-02-01

It is increasingly important to understand the combined influence of the main drivers of coastal risk due to sea level rise and the potential increase in extreme weather events. An Asian Basin stochastic typhoon set was used to force a storm surge model of Taiwan to investigate the interaction between storm surge and high river discharges (50, 100 and 200 year return period discharges) in the Tamsui River. Taiwan is a mountainous country leading to the combined risk of surge and high river discharge occurring simultaneously in estuary regions. The typhoon tracks were selected using a Hurricane Surge Index (Kantha, 2006) and cross the northern tip of Taiwan with maximum sustained winds (Vmax) between 51 m/s and 75 m/s (Cat 3-5). Peak surge elevations in the Tamsui River range from 5.7 m to 10.3 m. The surge interacts with the river flow to induce changes in the water elevation between -8 m and 4 m depending on the surge elevation and river discharge and increases the inundated area in the range 37 km to 204 km. Significant positive interactions occur in the Tamsui Estuary (Fig. 1a) but do not have implications for increased inundation and occur at the start of the flood phase and the end of the ebb phase as previously shown in idealized test cases (Maskell et al., 2013). Current vectors in the estuary show that at the time leading up to high water the river outflow starts to become dominant in the mid-channel reducing maximum water levels by up to 10% in the combined surge and river solution. However, surge inhibits downstream propagation of the flood wave in the upper river channels increasing water levels by up to 2 m. The maximum inundated area (1330 km2) is caused by the combination of defence overflow due to the maximum surge (10.27 m) and increased river levels (RP100) in the upper channels leading to significant inundation either side of the Keelung River (Fig. 1b). The Erchung floodway is effective in diverting some of the flow (up to 10,443 m3/s) reducing

[Challenges and countermeasures of forestry schistosomiasis control programs in ecological priority of Yangtze River economic belt development].

PubMed

Ning, Su; Yong-Jie, Xu

2016-12-13

Relevant projects carried out within the Yangtze River economic belt on the impact of schistosomiasis epidemic and transmission are important issues for "ecological priority" in the process of implementing the strategy. The key problems of schistosomiasis epidemic risk, epidemic happening repeatedly, difficulty of rehabilitating Oncomelania hupensis snail control and schistosomiasis prevention forest, lag of evaluation system and platform construction, lack of basic research, et al. were analyzed in the Yangtze River economic belt taking "ecological priority" as the basis in this paper. Then corresponding countermeasures to these challenges were put forward so as to provide the reference for the national forestry schistosomiasis control programs, which include: execution of the comprehensive prevention and control strategy, scheming of the new round of forestry schistosomiasis control programs, strengthening schistosomiasis prevention and control, promoting productivity in existing forestry to consolidate and improve the achievements of previous forestry schistosomiasis control programs, and promoting the intensity of technological innovation to improve the technological level of forestry schistosomiasis control programs.

Modelling Suspended Sediment Transport in Monsoon Season: A Case Study of Pahang River Estuary, Pahang, Malaysia

NASA Astrophysics Data System (ADS)

Zakariya, Razak; Ahmad, Zuhairi; Saad, Shahbudin; Yaakop, Rosnan

2013-04-01

Sediment transport based on 2-dimensional real time model was applied to Pahang River estuary, Pahang, Malaysia and has been evaluated and verified with time series of tidal elevation, flow and suspended sediment load. Period of modelling was during highest high tide and lowest low tide in Northeast Monsoon (NE) which happened in December 2010 and Southwest Monsoon (SW) in July 2011. Simulated model outputs has been verify using Pearson's coefficient and has showed high accuracy. The validated model was used to simulate hydrodynamic and sediment transport of extreme conditions during both monsoon seasons. Based on field measurement and model simulation, tidal elevation and flow velocity, freshwater discharge of Pahang River were found to be higher during NE Monsoon. Based on the fluxes, the estuary also showed 'ebb-dominant' characteristic during highest high tide and lowest low tide in NE monsoon and normal ebbing-flooding characteristics during SW monsoon. In the Pahang River estuary, inflow and outflow patterns were perpendicular to the open boundary with circular flow formed at the shallow area in the middle of estuary during both monsoons. Referring to sea water intrusion from the river mouth, both seasons show penetration of more than 9 km (upstream input boundary) during higher high water tide. During higher lower water tide, the water intrusion stated varies which 5.6km during NE monsoon and 7.8km during SW monsoon. Regarding to the times lap during high tide, the sea water takes 2.8 hours to reach 9km upstream during NE monsoon compared to 1.9 hour during SW monsoon. The averages of suspended sediment concentration and suspended sediment load were higher during Northeast monsoon which increased the sedimentation potentials.Total of suspended sediment load discharged to the South China Sea yearly from Pahang River is approximately 96727.5 tonnes/day or 3.33 tonnes/km2/day which 442.6 tonnes/day during Northeast Monsoon and 25.3 tonnes/day during Southwest

[Spatial distribution and ecological risk assessment of heavy metals in the estuaries surface sediments from the Haihe River Basin].

PubMed

Lü, Shu-Cong; Zhang, Hong; Shan, Bao-Qing; Li, Li-Qing

2013-11-01

It is well known that the rivers in the Haihe River Basin have been seriously polluted. However, what is the present condition of the estuary pollution and how the polluted inland rivers affect the estuary areas are not clear. 10 main estuaries of the Haihe River Basin were selected to measure the contents of typical heavy metals (Pb, Cu, Zn, Cd, Cr and Ni) in the surface sediments and to analyze the spatial distribution of these heavy metals. The potential ecological risk index was used to assess the ecological risk of the six heavy metals in the estuaries. The results showed that the contents of Pb, Cu, Zn, Cd, Cr and Ni in the surface sediments of the 10 estuaries were all higher than their background values in the main local soil types and the contents of Cu, Ni and Pb were 2.3-2.6 times as high as their background values, which indicated that the estuaries were contaminated by the six heavy metals. The results also indicated that the contents of the six heavy metals in surface sediment varied from one estuary to another. The four heavy metals of Cr, Cu, Ni and Zn had bigger spatial differences than Pb and Cd in the contents in sediment from different estuaries. The contents of Cr, Cu, Ni and Zn in sediment were higher in the estuaries of the Yongdingxin River, Ziyaxin River and Beipai River than those in the other estuaries, and there were significant correlations between each other (R(Cu-Zn) = 0.891, R(Cu-Cr) = 0.927, R(Cu-Ni) = 0.964, R(Zn-Cr) = 0.842, R(Zn-Ni) = 0.939, and R(Cr-Ni) = 0.879, P < 0.01), which indicated that they possibly came from the same sources. Moreover, the contents of Cr, Cu, Ni and Zn in sediment also had significant correlations with the populations of sub-river basins with correlation coefficients of 0.855, 0.806, 0.867 and 0.855 (P < 0.01), respectively. The contents of Cd and Pb had smaller spatial differences in sediment from different estuaries than the other heavy metals, with the values ranged 23.3-95.8 mg x kg(-1) and 0

Sedimentary framework of the Potomac River estuary, Maryland

USGS Publications Warehouse

Knebel, Harley J.; Martin, E. Ann; Glenn, J.L.; Needell, Sally W.

1981-01-01

Analyses of seismic-reflection profiles, sediment cores, grab samples, and side-scan sonar records, along with previously collected borehole data, reveal the characteristics, distribution, and geologic history of the shallow strata beneath the Potomac River estuary. The lowermost strata are sediments of the Chesapeake Group (lower Miocene to lower Pleistocene) that crop out on land near the shore but are buried as much as 40 m below the floor of the estuary. The top of these sediments is an erosional unconformity that outlines the Wisconsinan valley of the Potomac River. This valley has a sinuous trend, a flat bottom, a relief of 15 to 34 m, and axial depths of 34 to 54 m below present sea level. During the Holocene transgression of sea level, the ancestral valley was filled with as much as 40 m of sandy and silty, fluvial-to-shallow estuarine sediments. The fill became the substrate for oyster bars in the upper reach and now forms most marginal slopes of the estuary. Since sea level approached its present position (2,000 to 3,000 yr ago), the main channel has become the locus of deposition for watery, gray to black clay or silty clay, and waves and currents have eroded the heterogeneous Quaternary sediments along the margins, leaving winnowed brown sand on shallow shoreline flats. Pb-210 analyses indicate that modern mud is accumulating at rates ranging from 0.16 to 1.80 cm/yr, being lowest near the mouth and increasing toward the head of the estuary. This trend reflects an increased accumulation of fine-grained fluvial sediments near the turbidity maximum, similar to that found in nearby Chesapeake Bay. The present annual accumulation of mud is about 1.54 million metric tons; the cumulative mass is 406 million metric tons.

Invasion by stages in the St Louis River estuary

EPA Science Inventory

The St. Louis River estuary is recognized as an invasive species “hotspot” - the harbor ranks among the top locations in the Great Lakes reporting the first occurrence of new, aquatic non-native species. To date, 18 non-native benthic invertebrate, 4 non-native crusta...

Spatio-temporal pattern of schistosomiasis in Anhui Province, East China: Potential effect of the Yangtze River - Huaihe River Water Transfer Project.

PubMed

Cao, Zhi-Guo; Li, Si; Zhao, Ya-E; Wang, Tian-Ping; Bergquist, Robert; Huang, Yin-Yin; Gao, Feng-Hua; Hu, Yi; Zhang, Zhi-Jie

2018-05-09

Anhui Province has been one of typical epidemic areas of schistosomiasis in East China as a wide range of large lake and marshland regions provide an ideal environment for growth and reproduction of the intermediate snail host. With the completion of the Yangtze River-Huaihe River Water Transfer Project (YHWTP), launched by the end of 2016, the epidemic areas are expected to expand and controlling schistosomiasis remains a challenge. Based on annual surveillance data at the county level in Anhui for the period 2006-2015, spatial and temporal cluster analyses were conducted to assess the pattern of risk through spatial (Local Moran's I and flexible scan statistic) and space-time scan statistic (Kulldorff). It was found that schistosomiasis sero-prevalence was dramatically reduced and maintained at a low level. Cluster results showed that spatial extent of schistosomiasis contracted, but snail distribution remained geographically stable across the study area. Clusters, both for schistosomiasis and snail presence, were common along the Yangtze River. Considering the effect of the ongoing YHWTP on the potential spread of schistosomiasis, Zongyang County and Anqing, which will be transected by the new water-transfer route, should be given a priority for strengthened surveillance and control. Attention should also be paid to Guichi since it is close to one of the planned inlets of the YHWTP. Copyright © 2018 Elsevier B.V. All rights reserved.

Study on the Evaluation of Economic Support Index for Pig Breeding in Water Network Area of Middle Reaches of Yangtze River

NASA Astrophysics Data System (ADS)

Leng, Bi-Bin; Zhang, Qi-zhen; Lai, Wen-wei; Tang, Xin-Fan

2018-06-01

The central region of China boasts a long history, abundant resources, convenient transportation, advanced economy, a strong industrial and agricultural foundation and a rapid development of modern service industry, with about 10.7% of the country's total land area, 26.5% of the country's population and a GDP of about 21.4% of the country's total . As the population center, transportation hub, economic hinterland and important market, it is the second echelon of China's economic development; the central region of China plays an important role in the division of labor in China. The middle reaches of the Yangtze River water network includes four neighboring provinces- Hubei, Hunan, Anhui and Jiangxi. Although all four provinces are located in the middle of the Yangtze River Basin, there are still quite some differences. Based on the 2017 Statistical Yearbook data, this paper studies the economic supportive index of pig breeding in four provinces located in the water network area of the middle reaches of the Yangtze River in Jiangxi, Hubei, Hunan and Anhui. The evaluation results show that among the four provinces, the socio-economic conditions of Hubei Province can most support the large-scale cultivation of live pigs, and the support of Jiangxi Province is the weakest.

Lower Columbia River and Estuary Habitat Monitoring Study, 2011 - Final Report

DOE Office of Scientific and Technical Information (OSTI.GOV)

Borde, Amy B.; Kaufmann, Ronald M.; Cullinan, Valerie I.

The Ecosystem Monitoring Program is a collaborative effort between the Lower Columbia River Estuary Partnership (LCREP), University of Washington, Wetland Ecosystem Team (UW), US Geological Survey, Water Science Center (USGS), National Oceanic and Atmospheric Administration, National Marine Fisheries Service (NOAA-Fisheries, hereafter NOAA), and Pacific Northwest National Laboratory, Marine Sciences Laboratory (PNNL). The goal of the program is to conduct emergent wetland monitoring aimed at characterizing salmonid habitats in the lower Columbia River and estuary (LCRE) from the mouth of the estuary to Bonneville Dam (Figure 1). This is an ecosystem based monitoring program focused on evaluating status and trends inmore » habitat and reducing uncertainties regarding these ecosystems to ultimately improve the survival of juvenile salmonids through the LCRE. This project comprehensively assesses habitat, fish, food web, and abiotic conditions in the lower river, focusing on shallow water and vegetated habitats used by juvenile salmonids for feeding, rearing and refugia. The information is intended to be used to guide management actions associated with species recovery, particularly that of threatened and endangered salmonids. PNNL’s role in this multi-year study is to monitor the habitat structure (e.g., vegetation, topography, channel morphology, and sediment type) as well as hydrologic patterns.« less

Estimation of groundwater and nutrient fluxes to the Neuse River estuary, North Carolina

USGS Publications Warehouse

Spruill, T.B.; Bratton, J.F.

2008-01-01

A study was conducted between April 2004 and September 2005 to estimate groundwater and nutrient discharge to the Neuse River estuary in North Carolina. The largest groundwater fluxes were observed to occur generally within 20 m of the shoreline. Groundwater flux estimates based on seepage meter measurements ranged from 2.86??108 to 4.33??108 m3 annually and are comparable to estimates made using radon, a simple water-budget method, and estimates derived by using Darcy's Law and previously published general aquifer characteristics of the area. The lower groundwater flux estimate (equal to about 9 m3 s-1), which assumed the narrowest groundwater discharge zone (20 m) of three zone widths selected for an area west of New Bern, North Carolina, most closely agrees with groundwater flux estimates made using radon (3-9 m3 s-1) and Darcy's Law (about 9 m3 s-1). A groundwater flux of 9 m 3 s-1 is about 40% of the surface-water flow to the Neuse River estuary between Streets Ferry and the mouth of the estuary and about 7% of the surface-water inflow from areas upstream. Estimates of annual nitrogen (333 tonnes) and phosphorus (66 tonnes) fluxes from groundwater to the estuary, based on this analysis, are less than 6% of the nitrogen and phosphorus inputs derived from all sources (excluding oceanic inputs), and approximately 8% of the nitrogen and 17% of the phosphorus annual inputs from surface-water inflow to the Neuse River estuary assuming a mean annual precipitation of 1.27 m. We provide quantitative evidence, derived from three methods, that the contribution of water and nutrients from groundwater discharge to the Neuse River estuary is relatively minor, particularly compared with upstream sources of water and nutrients and with bottom sediment sources of nutrients. Locally high groundwater discharges do occur, however, and could help explain the occurrence of localized phytoplankton blooms, submerged aquatic vegetation, or fish kills. 

Hydrochemistry of the Tumen River Estuary, Sea of Japan

NASA Astrophysics Data System (ADS)

Tishchenko, P. Ya.; Semkin, P. Yu.; Pavlova, G. Yu.; Tishchenko, P. P.; Lobanov, V. B.; Marjash, A. A.; Mikhailik, T. A.; Sagalaev, S. G.; Sergeev, A. F.; Tibenko, E. Yu.; Khodorenko, N. D.; Chichkin, R. V.; Shvetsova, M. G.; Shkirnikova, E. M.

2018-03-01

The hydrological and hydrochemical parameters of the Tumen River estuary were collected at 13 stations in May and October 2015. Vertical temperature, conductivity, dissolved oxygen, chlorophyll fluorescence, and turbidity profiles were obtained. Water was sampled from the surface and bottom layer. The water samples were analyzed for major ions, pH, salinity, concentrations of dissolved oxygen, major nutrients, dissolved organic carbon, humic matter, and δ18O and δD isotopes. This estuary is attributed to microtidal type with a flushing time of about 10 h. A phytoplakton bloom occurred in the top layer of the estuary. For surface horizons, the hydrochemical parameters show a linear correlation with salinity. In the bottom horizons, all these parameters, except for major ions and δ18O and δD isotopes, reveal substantial nonconservative behavior. The nonconservative behavior of the hydrochemical parameters in the bottom waters was mainly caused by degradation of the phytoplankton biomass at the water/sediment interface. Hypoxic conditions were established in the bottom waters of the estuary in May.

Trace metal pollution and carbon and nitrogen isotope tracing through the Yongdingxin River estuary in Bohai Bay, Northern China.

PubMed

Sun, Conghui; Wei, Qi; Ma, Lixia; Li, Li; Wu, Guanghong; Pan, Ling

2017-02-15

A tide gate was built in 2010 to prevent seawater from moving upstream into the Yongdingxin River estuary in Bohai Bay, Northern China. We analysed the concentrations of Hg, Cd, Pb, TOC, TN, δ 13 C and δ 15 N and studied their variations in the surface layer and vertical profiles of sediment cores collected from the Yongdingxin River estuary. Contamination factors and geo-accumulation indices were calculated for each metal, which revealed high levels of contamination for Hg and Cd in the sediments, likely from anthropogenic sources. δ 13 C and δ 15 N were used as natural tracers to determine the sources of TOC and TN. The results revealed that sewage was the main source of TOC, while TN may have more than one source in the Yongdingxin River estuary. Sewage dominated trace metal pollution in the Yongdingxin River estuary. Our results provide a baseline for trace metal contamination in an estuary facing a large water project. Copyright © 2016 Elsevier Ltd. All rights reserved.

Trace metals in the Ob and Yenisei Rivers' Estuaries (the Kara Sea).

NASA Astrophysics Data System (ADS)

Demina, L. L.

2014-12-01

Behavior of some trace metals (Al, As, Cd, Co, Cr, Cu, Fe, Mn, Ni and Pb) in water column (soluble <0.45 µm and particulate fractions) and bottom sediments (surface and cores) along the two transects from the Ob River and Yenisei River Estuaries to the Kara Sea was studied. The length of both transects was about 700 km. Water depth was 12-63 m, O2 dissolved :5.36-9.55 ml l-1. Along the transects salinity increased from 0.07 to 34.2 psu, while the SPM' concentration decreased from 10.31 to 0.31 mg/l. Total suspended particulate matter load is more than one order of magnitude higher in the Ob River Estuary comparing to that of the Yenisei River. It has led to a significant difference between the suspended trace metals' concentrations (µg/l) in water of the two estuaries. With salinity increase along transects Fe susp., Mn susp. and Zn susp. decreased by a factor of 100-500, that has led to a growth of a relative portion of dissolved trace metals followed by their bioaccumulation (Demina et al., 2010). A strong direct correlation between suspended Cu, Fe and SPM mass concentration was found. For the first time along the Yenisei River' Estuary -the Kara Sea transect a direct positive correlation between Cu suspended and volume concentration of SPM (mg/ml3) was found, that was attributed to contribution of phytoplankton aggregates in the SPM composition. A trend of relationship between content of suspended As and pelitic fraction (2-10 µm) of SPM was firstly found in theses basins also. Study of trace metal speciation in the bottom sediments (adsorbed, associated with Fe-Mn (oxyhydr)oxides, organic matter and fixed in the mineral lattice or refractory) has revealed the refractory fraction to be prevailing (70-95% total content) for Fe, Zn, Cu, Co, Ni, Cr, Cd and Pb. That means that toxic heavy metals were not available for bottom fauna. Mn was predominantly found in the adsorbed and (oxyhydr)oxides geochemically labile forms, reflecting the redox condition change

Physical, Hydrological, and Biological Characteristics of the Loxahatchee River Estuary, Florida

USGS Publications Warehouse

McPherson, Benjamin F.; Sabanskas, Maryann; Long, William A.

1982-01-01

The Loxahatchee River estuary empties into the Atlantic Ocean at Jupiter Inlet in southeastern Florida. Although relatively small, the estuary is important for its esthetic value and for its sport fishing, boating, recreation, tourism, and prime residential development. In recent years, the condition of the estuary has become of concern to many citizens and agencies of the State. In response to this concern, the U.S. Geological Survey planned and carried out an in-depth environmental investigation. The events that led to the investigation and the objectives of the investigation are outlined in a recent U.S. Geological Survey report by McPherson and Sabanskas (WRI 80-1109).

[Monthly changes in the benthic macro-invertebrate community structure in the habitats of Phragmites australis marsh in the Dongtan wetland of the Yangtze River estuary, China].

PubMed

Zhang, Heng; Ye, Jin Yu; Liang, Xiao Li; Zhu, Xiao Jing; Jin, Shao Fei; Chen, Yuan Ge; Zhang, Jia Rui; Dai, Yang

2017-04-18

Based on the data of the benthic macro-invertebrates community in the Phragmites australis marsh in the Dongtan Wetland of the Yangtze River estuary collected from May 2015 to April 2016, we evaluated the monthly variations in the species composition, biodiversity and community structure of the benthic macro-invertebrates. The results showed that the average height and degree of coverage for P. australis increased monthly from March to August, and then deceased from September. The density and aboveground biomass (dry mass, g) of P. australis peaked in July. A total of twenty species (including 2 species only identified to genus level and 2 species identified to family level) were found in the survey periods, including 11 Gastropoda, 5 Malacostraca, 2 Insecta and 2 Polychaeta. Three snail species (Assiminea latericea, Assiminea violacea and Cerithideopsis largillierti) dominated the benthic communities in terms of numerical abundance. The number of epifauna species was the most (11 species), followed by 5 burrowing species and 4 infauna species. There were significant monthly variations in the density and biomass of the macro-invertebrates. The density and biomass of benthic community reached the maximum in August. The Margalef's species richness index (D) and Shannon index (H) showed significant differences monthly, but Pielou's index (J) except in November. Three macro-zoobenthic assemblages were identified with the 42% similarity level. The non-Metric Multidimensional scaling plot indicates that the benthic community in May, October and November was distinct compared to that in the other months. The present study suggested the density of the benthic macro-invertebrates community in the P. australis marshes was somewhat correlated with water temperature, underground biomass and salinity. But those correlation were not significant (P>0.05). Because of the continuous impact of anthropogenic activities, the biodiversity of the benthic macro-invertebrate community has

Formation of A-type granites in the Lower Yangtze River Belt: A perspective from apatite geochemistry

NASA Astrophysics Data System (ADS)

Jiang, Xiao-Yan; Li, He; Ding, Xing; Wu, Kai; Guo, Jia; Liu, Ji-Qiang; Sun, Wei-Dong

2018-04-01

Apatite is ubiquitous in A-type granites, and can be used to elucidate the volatile contents of the silicate melt, which reflect its source characteristics. A-type granites have been recognized as a distinct group of granites. A1- and A2-type subgroups are produced under different extensional settings. However, the details of the mechanisms behind the distinctive geochemical characteristics of A1- and A2-type granites remain obscure. Belts of Cretaceous A1- and A2-type granites occur along the Lower Yangtze River Belt in eastern China. Here we investigated the major and trace element compositions of apatites from contemporary A1- and A2-type granites at different localities along the Lower Yangtze River Belt, in order to decipher their discrepant source processes. Apatites from A1- and A2-type granites show similar major and trace elements, but differ in their F and Cl concentrations. Apatites from A1-type granites in the eastern part of the Lower Yangtze River Belt have much lower F and higher Cl concentrations compared to A2-type granites in the western part. Moreover, from the east to the west, the F concentrations of apatites from A1-type granites increase, while the Cl concentrations decline. In a subducted plate, F is retained by amphibole, chlorite, serpentine and mica minerals through the amphibolite stage, and finally by phengite and lawsonite during the eclogite stage, whereas, Cl is controlled by amphibole, chlorite and serpentine. The high and varied Cl concentrations in A1 subgroup apatites, therefore, may be attributed to the breakdown of amphibole, chlorite and/or serpentine decomposition during partial melting of subducted oceanic crust releasing a large amount of Cl at shallower depth. In contrast, F is transported to deeper depths in the subducted oceanic crust, and released through breakdown of phengite and lawsonite, making an important contribution to the formation of A2-type granites. Apatites from A1- and A2-type granite samples show regular

Influences of hydrological regime on heavy metal and salt ion concentrations in intertidal sediment from Chongming Dongtan, Changjiang River estuary, China

NASA Astrophysics Data System (ADS)

Zhao, Jiale; Gao, Xiaojiang; Yang, Jin

2017-11-01

The tidal flat along the Changjiang (Yangtze) River estuary has long been reclaimed for the agricultural purposes, with the prevailing hydrological conditions during such pedogenic transformations being of great importance to their successful development. In this study, samples of surface sediment from Chongming Dongtan, situated at the mouth of the Changjiang River estuary, were collected and analyzed in order to understand how hydrological management can influence the concentrations of heavy metals and salt ions in pore water, and chemical fractionation of heavy metals during the reclamation process. We performed a series of experiments that simulated three different hydrological regimes: permanent flooding (R1), alternative five-day periods of wetting and drying (R2), continuous field capacity (R3). Our results exhibited good Pearson correlations coefficients between heavy metals and salt ions in the pore water for both R1 and R2. In particular, the concentrations of salt ions in the pore water decreased in all three regimes, but showed the biggest decline in R2. With this R2 experiment, the periodic concentration patterns in the pore water varied for Fe and Mn, but not for Cr, Cu, Pb and Zn. Neither the fractionation of Ni nor the residual fractions of any metals changed significantly in any regime. In R1, the reducible fractions of heavy metals (Cr, Cu, Zn and Pb) in the sediment decreased, while the acid extractable fractions increased. In R2, the acid extractable and the reducible fractions of Cr, Cu, Zn and Pb both decreased, as did the oxidizable fraction of Cu. These data suggest that an alternating hydrological regime can reduce both salinity and the availability of heavy metals in sediments.

Distribution and sources of the polycyclic aromatic hydrocarbons in the sediments of the Pearl River estuary, China.

PubMed

Zhang, Jian-Dong; Wang, You-Shao; Cheng, Hao; Jiang, Zhao-Yu; Sun, Cui-Ci; Wu, Mei-Lin

2015-10-01

The Pearl River delta, one of the most prosperous economically region in China, has experienced significant contaminant inputs. However, the dynamics of pollutants in the Pearl River estuary and the adjacent coastal areas are still unclear at present. In the paper, distribution and sources of polycyclic aromatic hydrocarbons (PAHs) were investigated in the surface sediments of the Pearl River estuary. The total PAHs concentrations ranged from 126.08 to 3828.58 ng/g with a mean value of 563.52 ng/g, whereas the highest PAHs were observed in Guangzhou channel. Among the U.S. Environmental Protection Agency's 16 priority PAHs, PAHs with 3-4 rings exhibited relative higher levels. A positive relationship was found between PAHs and total organic carbon. The source analysis further showed that the major sources of PAHs in the Pearl River estuary were originated from the pyrolytic inputs, reflecting a mixed energy structure such as wood, coal and petroleum combustion. In summary, although PAHs in Lingding Bay and the adjacent coastal areas of the Pearl River estuary exhibited a relatively low pollution level, the relatively high pollution level of PAHs in Guangzhou channel will be attended.

[Seasonal and semi-lunar changes in fish community structure in low salinity intertidal area of Yangtze estuary].

PubMed

Zhang, Heng; He, Wen-Shan; Tong, Chun-Fu; Lu, Jian-Jian

2008-05-01

Based on the survey of the fishes in low salinity intertidal area of the Yangtze estuary from spring (May) 2006 to winter (February) 2007, the seasonal and semi-lunar changes of fish species and abundances were analyzed. A total of 53 fish species were collected, most of which belonged to Cyprinidae, followed by Gobiidae, and few of other families. The fish species and average abundance were higher in spring, summer, and autumn than in winter and lower in low tides than in high tides in four seasons. Shannon-Weaver (H') value had a greater fluctuation in a tidal cycle, and was appreciably lower in low tides than in high tides. The fish species and abundance were clustered into two groups, i. e., that of winter, and of the other seasons. As for the whole year, the abundance had the highest positive correlation with water temperature, then with tide height, and lowest with water salinity.

Heavy metal partitioning of suspended particulate matter-water and sediment-water in the Yangtze Estuary.

PubMed

Feng, Chenghong; Guo, Xiaoyu; Yin, Su; Tian, Chenhao; Li, Yangyang; Shen, Zhenyao

2017-10-01

The partitioning of ten heavy metals (As, Cd, Co, Cr, Cu, Hg, Ni, Pb, Sb, and Zn) between the water, suspended particulate matter (SPM), and sediments in seven channel sections during three hydrologic seasons in the Yangtze Estuary was comprehensively investigated. Special attention was paid to the role of tides, influential factors (concentrations of SPM and dissolved organic carbon, and particle size), and heavy metal speciation. The SPM-water and sediment-water partition coefficients (K p ) of the heavy metals exhibited similar changes along the channel sections, though the former were larger throughout the estuary. Because of the higher salinity, the K p values of most of the metals were higher in the north branch than in the south branch. The K p values of Cd, Co, and As generally decreased from the wet season to the dry season. Both the diagonal line method and paired samples t-test showed that no specific phase transfer of heavy metals existed during the flood and ebb tides, but the sediment-water K p was more concentrated for the diagonal line method, owing to the relatively smaller tidal influences on the sediment. The partition coefficients (especially the K p for SPM-water) had negative correlations with the dissolved organic carbon (DOC) but positive correlations were noted with the particle size for most of the heavy metals in sediment. Two types of significant correlations were observed between K p and metal speciation (i.e., exchangeable, carbonate, reducible, organic, and residual fractions), which can be used to identify the dominant phase-partition mechanisms (e.g., adsorption or desorption) of heavy metals. Copyright © 2017 Elsevier Ltd. All rights reserved.

Continuous resistivity profiling and seismic-reflection data collected in 2006 from the Potomac River Estuary, Virginia and Maryland

USGS Publications Warehouse

Cross, V.A.; Foster, D.S.; Bratton, J.F.

2010-01-01

In 2006 the U.S. Geological Survey conducted a geophysical survey on the Chesapeake Bay and the Potomac River Estuary in order to test hypotheses about groundwater flow under and into Chesapeake Bay. Resource managers are concerned about nutrients that are entering the estuary via submarine groundwater discharge and are contributing to eutrophication. The research carried out as part of this study was designed to help refine nutrient budgets for Chesapeake Bay by characterizing submarine groundwater flow and groundwater discharge beneath part of the bay?s mainstem and a major tributary, the Potomac River Estuary. The data collected indicate that plumes of reduced-salinity groundwater are commonly present along the shorelines of Chesapeake Bay and the Potomac River Estuary. Data also show that buried paleochannels generally do not serve as conduits for flow of groundwater from land to underneath the bay and estuary but rather may focus discharge of reduced-salinity water along their flanks, and provide routes for migration of saltwater into the sediments.

Seasonal occurrence of helminths in the anadromous fish Coilia nasus (Engraulidae): parasite indicators of fish migratory movements.

PubMed

Li, Wen X; Song, Rui; Wu, Shan G; Zou, Hong; Nie, Pin; Wang, Gui T

2011-04-01

To understand the seasonal migration of the anadromous Coilia nasus , we attempted to identify the parasites infecting C. nasus and determine their seasonal occurrence. From June 2007 to July 2008, a survey of 775 C. nasus individuals from the estuary of the Yangtze River and the coast of the East China Sea revealed more than 7,300 parasites associated with the gills and alimentary tracts of C. nasus . The following 6 helminth taxa were identified, i.e., the monogeneans Heteromazocraes lingmueni and Helciferus tenuis, the digenean Elytrophallus coiliae, the acanthocephalan Acanthosentis cheni , and larvae of the nematodes Anisakis simplex and Contracaecum sp., all of which are marine or brackish-water parasites. The absence of freshwater helminths suggested that the parasites acquired in freshwater may have been accidentally, and easily, lost by the time the fish had reached the estuary and coast. Contrary to seasonal occurrence of the parasites' life cycles, the lowest mean abundance and prevalence of H. lingmueni and A. cheni occurred in August, which suggested the immigration of C. nasus from freshwater to the Yangtze estuary, with lower parasite burdens. The highest mean abundance and prevalence of the nematodes A. simplex and Contracaecum sp. in May and June, and the lowest in August, indicated the arrival of the fish from the coast and the Yangtze River, to the estuary, respectively. These findings suggested that a majority of the fish prepared for spawning migration in the estuary in spring and early summer and returned to the estuary after spawning in the lower and middle reaches of the Yangtze River in late summer.

Quantifying nitrogen inputs to the Choptank River estuary

NASA Astrophysics Data System (ADS)

Mccarty, G.; Hapeman, C. J.; Sadeghi, A. M.; Hively, W. D.; Denver, J. M.; Lang, M. W.; Downey, P. M.; Rice, C. P.

2015-12-01

The Chesapeake Bay is the largest estuary in the US, and over 50% of its streams have been rated as poor or very poor, based on the biological integrity yearly index. The Choptank River, a Bay tributary on the Delmarva Peninsula, is dominated by intensive corn and soybean farming associated with poultry and some dairy production. The Choptank River is under Environmental Protection Agency (USEPA) total maximum daily load restrictions. However, reducing nonpoint source pollution contributions from agriculture requires that source predictions be improved and that mitigation and conservation measures be properly targeted. Therefore, new measurement strategies have been implemented. In-situ sensors have been deployed adjacent to US Geological Survey gauging stations in the Tuckahoe and Greensboro sub-basins of the Choptank River watershed. These sensors measure stream water concentrations of nitrate along and water quality parameters every 30 min. Initial results indicate that ~40% less nitrate is exported from the Greensboro sub-basin, even though the total amount of agricultural land use is similar to that in the Tuckahoe sub-basin. This is most likely due to more efficient nitrate processing in the Greensboro sub-basin where the amount of cropland on poorly-drained soils is much larger. Another potential nitrogen source to the Choptank River estuary is atmospheric deposition of ammonia. Over 550 million broilers are produced yearly on the Delmarva Peninsula potentially leading to the release of 20,000 Mtons of ammonia. USEPA recently estimated that as much as 22% of nitrogen in the Bay is due to ammonia deposition. We have initiated a collaborative effort within the LTAR network to increase coverage of ammonia sampling and to explore the spatial and temporal variability of ammonia, particularly in the Choptank River watershed. All these measurements will be useful in improving the handling of nitrogen sources and its fate and transport in the Chesapeake Bay model.

Thyroid hormone disrupting activities associated with phthalate esters in water sources from Yangtze River Delta.

PubMed

Shi, Wei; Zhang, Feng-Xian; Hu, Guan-Jiu; Hao, Ying-Qun; Zhang, Xiao-Wei; Liu, Hong-Ling; Wei, Si; Wang, Xin-Ru; Giesy, John P; Yu, Hong-Xia

2012-07-01

Thyroid hormone disrupting compounds in water sources is a concern. Thyroid hormone (TH) agonist and antagonist activities of water sources from the Yangtze River, Huaihe River, Taihu Lake and ground water in the Yangtze River Delta region were evaluated by use of a TH reporter gene assay based on the green monkey kidney fibroblast (CV-1). While weak TH receptor (TR) agonist potency was observed in only one of 15 water sources, antagonist potency was present in most of the water sources. TR antagonist equivalents could be explained by the presence of dibutyl phthalate (DBP), with concentrations ranging from 2.8×10(1) to 1.6×10(3) μg DBP /L (ATR-EQ(50)s). None of the ground waters exhibited TH agonist potencies while all of the samples from Taihu Lake displayed notable TR antagonist potencies. To identify the responsible thyroid active compounds, instrumental analysis was conducted to measure a list of potential thyroid-disrupting chemicals, including organochlorine (OC) pesticides and phthalate esters. Combining the results of the instrumental analysis with those of the bioassay, DBP was determined to account for 17% to 144% of ATR-EQ(50)s in water sources. Furthermore, ATR-EQ(20-80) ranges for TR antagonist activities indicated that samples from locations WX-1 and WX-2 posed the greatest health concern and the associated uncertainty may warrant further investigation. Copyright © 2011 Elsevier Ltd. All rights reserved.

Salinity and turbidity distributions in the Brisbane River estuary, Australia

NASA Astrophysics Data System (ADS)

Yu, Yingying; Zhang, Hong; Lemckert, Charles

2014-11-01

The Brisbane River estuary (BRE) in Australia not only plays a vital role in ecosystem health, but is also of importance for people who live nearby. Comprehensive investigations, both in the short- and long-term, into the salinity and turbidity distributions in the BRE were conducted. Firstly, the analysis of numerical results revealed that the longitudinal salinity varied at approximately 0.45 and 0.61 psu/h during neap and spring tides, respectively. The turbidity stayed at a higher level and was less impacted by tide in the upper estuary, however, the water cleared up while the tide changed from flood to ebb in the mid and lower estuary. The second investigation into the seasonal variations of salinity and turbidity in the BRE was conducted, using ten-year field measurement data. A fourth-order polynomial equation was proposed, describing the longitudinal variation in salinity dilution changes as the upstream distance in the BRE during the wet and dry seasons. From the observation, the mid and upper estuaries were vertically well-mixed during both seasons, but the lower BRE was stratified, particularly during the wet season. The estuary turbidity maximum (ETM) zone was about 10 km longer during the wet season than the dry season. Particular emphasis was given to the third investigation into the use of satellite remote sensing techniques for estimation of the turbidity level in the BRE. A linear relationship between satellite observed water reflectance and surface turbidity level in the BRE was validated with an R2 of 0.75. The application of satellite-observed water reflectance therefore provided a practical solution for estimating surface turbidity levels of estuarine rivers not only under normal weather conditions, but also during flood events. The results acquired from this study are valuable for further hydrological research in the BRE and particularly prominent for immediate assessment of flood impacts.

Historical Relationships Between Research and Resource Management in the Apalachicola River Estuary.

PubMed

Livingston, Robert J

1991-11-01

A continuous field research effort has been carried out in the Apalachicola River estuary since March 1972. The information generated from this interdisciplinary study has been directly applied to the management of the Apalachicola resource by means of close associations among local, state, and federal officials and university scientists. During the early years, scientific data were instrumental in the prevention of the impoundment of the Apalachicola River. A series of regional studies was carried out to evaluate various forms of effects due to forestry activities, pesticides, and stormwater runoff from urban areas. A review was made of fisheries problems associated with dredging, overfishing, and marine pollution. Results of such studies were directly applied to local management questions. Research that linked the river wetlands with the estuary, in terms of the input of fresh water, nutrients, and organic matter, served as the basis for the purchase of extensive bottomland tracts. Other initiatives were carried out that were designed to protect the naturally high productivity of the river estuary. Further purchases of estuarine wetlands and barrier island properties were made that formed an almost continuous buffer of publicly held lands between upland developments and critical habitats and important populations of the bay system. A regional management plan was adopted that was designed to limit local municipal development in the estuarine region. Analyses of the long-term scientific data indicated that dominant, commercially important estuarine populations are associated with river flow, local salinity characteristics, and biological (predation, competition) interactions with the salinity regime and food web structure. Such interactions are not straight forward, however; they reflect complex interactions of the freshwater influxes and biological response in the estuary that are not well understood. Species-specific responses to the principal driving factors

Recent coarsening of sediments on the southern Yangtze subaqueous delta front: A response to river damming

NASA Astrophysics Data System (ADS)

Yang, H. F.; Yang, S. L.; Meng, Y.; Xu, K. H.; Luo, X. X.; Wu, C. S.; Shi, B. W.

2018-03-01

After more than 50,000 dams were built in the Yangtze basin, especially the Three Gorges Dam (TGD) in 2003, the sediment discharge to the East China Sea decreased from 470 Mt/yr before dams to the current level of 140 Mt/yr. The delta sediment's response to this decline has interested many researchers. Based on a dataset of repeated samplings at 44 stations in this study, we compared the surficial sediment grain sizes in the southern Yangtze subaqueous delta front for two periods: pre-TGD (1982) and post-TGD (2012). External factors of the Yangtze River, including water discharge, sediment discharge and suspended sediment grain size, were analysed, as well as wind speed, tidal range and wave height of the coastal ocean. We found that the average median size of the sediments in the delta front coarsened from 8.0 μm in 1982 to 15.4 μm in 2012. This coarsening was accompanied by a decrease of clay components, better sorting and more positive skewness. Moreover, the delta morphology in the study area changed from an overall accretion of 1.0 cm/yr to an erosion of - 0.6 cm/yr. At the same time, the riverine sediment discharge decreased by 70%, and the riverine suspended sediment grain size increased from 8.4 μm to 10.5 μm. The annual wind speed and wave height slightly increased by 2% and 3%, respectively, and the tidal range showed no change trend. Considering the increased wind speed and wave height, there was no evidence that the capability of the China Coastal Current to transport sediment southward has declined in recent years. The sediment coarsening in the Yangtze delta front was thus mainly attributed to the delta's transition from accumulation to erosion which was originally generated by river damming. These findings have important implications for sediment change in many large deltaic systems due to worldwide human impacts.

Consumption processes and food web structure in the Columbia River Estuary

NASA Astrophysics Data System (ADS)

Simenstad, Charles A.; Small, Lawrence F.; David McIntire, C.

Consumption processes at several trophic levels tend to coverage in the central (estuarine-mixing) region of the Columbia River estuary, where living and dentrital food resources are entrained within the energy null of the turbidity maximum zone. Primary consumers in this region are generalist and omnivorous feeders, capable of exploiting both autotrophic and heterotrophic food web pathways. In the presence of higher standing stocks of their prey resources, feeding by secondary and tertiary consumers is also concentrated, or more effective, in the estuarine mixing region of the estuary. During the 1980-1981 studies of the estuary, total consumer (metazoan) production averaged 5.5g C m -2 within the estuary. Of the estimated 15 x 10 3mt Cyy -1 attributed to primary consumption in the water column, 83% was the result of suspension-feeding pelagic zooplankton. In comparison to grazing on phytoplankton, it was estimated that approximately 84% of primary consumption in the water column was based on suspended detritus and, presumably, associated microbiota. Endemic primary,consumers, principally epibenthic crustaceans such as the calanoid copepod Eurytemora affinis, the harpacticoid copepod Scottolana canadensis, and the crangonid shrimp Crangon franciscorum, accounted for a high proportion of the consumption of suspended particles. Wertland herbivores inhabiting the estuary's extensive marshes, on the other hand, were estimated to account for only 2 to 17% of total estuarine primary consumption. Trophic linkages to secondary and tertiary consumers were more evenly apportioned among pelagic fishes, motile macroinvertebrates, and benthic infauna. High, comparatively unknown fluxes of migratory or wide-ranging tertiary consumers, such as piscivorous birds, seals and sea lions, made estimation of their annual consumption rates in the estuary highly tenuous. The physical processes of mixing and stratification, sediments accretion and erosion, and salinity intrusion appear to

A dynamic water-quality modeling framework for the Neuse River estuary, North Carolina

USGS Publications Warehouse

Bales, Jerad D.; Robbins, Jeanne C.

1999-01-01

As a result of fish kills in the Neuse River estuary in 1995, nutrient reduction strategies were developed for point and nonpoint sources in the basin. However, because of the interannual variability in the natural system and the resulting complex hydrologic-nutrient inter- actions, it is difficult to detect through a short-term observational program the effects of management activities on Neuse River estuary water quality and aquatic health. A properly constructed water-quality model can be used to evaluate some of the potential effects of manage- ment actions on estuarine water quality. Such a model can be used to predict estuarine response to present and proposed nutrient strategies under the same set of meteorological and hydrologic conditions, thus removing the vagaries of weather and streamflow from the analysis. A two-dimensional, laterally averaged hydrodynamic and water-quality modeling framework was developed for the Neuse River estuary by using previously collected data. Development of the modeling framework consisted of (1) computational grid development, (2) assembly of data for model boundary conditions and model testing, (3) selection of initial values of model parameters, and (4) limited model testing. The model domain extends from Streets Ferry to Oriental, N.C., includes seven lateral embayments that have continual exchange with the main- stem of the estuary, three point-source discharges, and three tributary streams. Thirty-five computational segments represent the mainstem of the estuary, and the entire framework contains a total of 60 computa- tional segments. Each computational cell is 0.5 meter thick; segment lengths range from 500 meters to 7,125 meters. Data that were used to develop the modeling framework were collected during March through October 1991 and represent the most comprehensive data set available prior to 1997. Most of the data were collected by the North Carolina Division of Water Quality, the University of North Carolina

Study on Spatial Spillover Effects of Logistics Industry Development for Economic Growth in the Yangtze River Delta City Cluster Based on Spatial Durbin Model

PubMed Central

Xu, Xinxing

2017-01-01

The overall entropy method is used to evaluate the development level of the logistics industry in the city based on a mechanism analysis of the spillover effect of the development of the logistics industry on economic growth, according to the panel data of 26 cities in the Yangtze River delta. On this basis, the paper uses the spatial durbin model to study the direct impact of the development of the logistics industry on economic growth and the spatial spillover effect. The results show that the direct impact coefficient of the development of the logistics industry in the Yangtze River Delta urban agglomeration on local economic growth is 0.092, and the significant spatial spillover effect on the economic growth in the surrounding area is 0.197. Compared with the labor force input, capital investment and the degree of opening to the world, and government functions, the logistics industry’s direct impact coefficient is the largest, other than capital investment; the coefficient of the spillover effect is higher than other control variables, making it a “strong engine” of the Yangtze River Delta urban agglomeration economic growth. PMID:29207555

Study on Spatial Spillover Effects of Logistics Industry Development for Economic Growth in the Yangtze River Delta City Cluster Based on Spatial Durbin Model.

PubMed

Xu, Xinxing; Wang, Yuhong

2017-12-04

The overall entropy method is used to evaluate the development level of the logistics industry in the city based on a mechanism analysis of the spillover effect of the development of the logistics industry on economic growth, according to the panel data of 26 cities in the Yangtze River delta. On this basis, the paper uses the spatial durbin model to study the direct impact of the development of the logistics industry on economic growth and the spatial spillover effect. The results show that the direct impact coefficient of the development of the logistics industry in the Yangtze River Delta urban agglomeration on local economic growth is 0.092, and the significant spatial spillover effect on the economic growth in the surrounding area is 0.197. Compared with the labor force input, capital investment and the degree of opening to the world, and government functions, the logistics industry's direct impact coefficient is the largest, other than capital investment; the coefficient of the spillover effect is higher than other control variables, making it a "strong engine" of the Yangtze River Delta urban agglomeration economic growth.

PPCPs in Jiulong River estuary (China): Spatiotemporal distributions, fate, and their use as chemical markers of wastewater.

PubMed

Sun, Qian; Li, Yan; Li, Mingyue; Ashfaq, Muhammad; Lv, Min; Wang, Hongjie; Hu, Anyi; Yu, Chang-Ping

2016-05-01

The occurrence and fate of 50 pharmaceuticals and personal care products (PPCPs) were investigated in the surface water of Jiulong River estuary in the southeast of China in spring, wet season, summer, autumn and winter. Results demonstrated a wide distribution of PPCPs in Jiulong River estuary, where 34 PPCPs were detected at least once and 5 PPCPs were detected in all the samples, including caffeine, diclofenac, metoprolol, methyl paraben, and propyl paraben. Spatial and seasonal variations were observed. Special emphasis was placed on the PPCP fate in the estuary. Most PPCPs showed a non-conservative behavior in the estuary, while the non-steroidal anti-inflammatory drugs and bisphenol A showed a pseudo-conservative behavior. The non-conservative and pseudo-conservative behavior was attributed to the combination of the seawater dilution, the introduction of PPCPs via the sewage water, and the physical, chemical, or biological removal processes. Furthermore, PPCP concentrations showed drastic variations in the turbidity maximum zones. To our best knowledge, this is the first work to indicate the pseudo-conservative behavior of PPCPs in the estuary, and to show the drastic variations of PPCPs in the turbidity maximum zone. In addition, the ratio of labile to conservative PPCPs was calculated to track the source of untreated sewage contamination. Results showed a significantly higher ratio compared to the average value in WWTP effluents, indicating the ubiquitous discharge of untreated domestic wastewater in Jiulong River estuary. In addition, the high ratio of bisphenol A to conservative PPCPs implied the potential input of untreated industrial wastewater in Jiulong River estuary. Copyright © 2016 Elsevier Ltd. All rights reserved.

Upriver transport of dissolved substances in an estuary and sub-estuary system of the lower James River, Chesapeake Bay

NASA Astrophysics Data System (ADS)

Hong, Bo; Shen, Jian; Xu, Hongzhou

2018-01-01

The water exchange between the James River and the Elizabeth River, an estuary and sub-estuary system in the lower Chesapeake Bay, was investigated using a 3D numerical model. The conservative passive tracers were used to represent the dissolved substances (DS) discharged from the Elizabeth River. The approach enabled us to diagnose the underlying physical processes that control the expansion of the DS, which is representative of potential transport of harmful algae blooms, pollutants from the Elizabeth River to the James River without explicitly simulating biological processes. Model simulations with realistic forcings in 2005, together with a series of processoriented numerical experiments, were conducted to explore the correlations of the transport process and external forcing. Model results show that the upriver transport depends highly on the freshwater discharge on a seasonal scale and maximum upriver transport occurs in summer with a mean transport time ranging from 15-30 days. The southerly/easterly wind, low river discharge, and neap tidal condition all act to strengthen the upriver transport. On the other hand, the northerly/westerly wind, river pulse, water level pulse, and spring tidal condition act to inhibit the upriver transport. Tidal flushing plays an important role in transporting the DS during spring tide, which shortens the travel time in the lower James River. The multivariable regression analysis of volume mean subtidal DS concentration in the mesohaline portion of the James River indicates that DS concentration in the upriver area can be explained and well predicted by the physical forcings (r = 0.858, p = 0.00001).

[Terrain gradient effect of ecosystem service value in middle reach of Yangtze River, China].

PubMed

Yang, Suo Hua; Hu, Shou Geng; Qu, Shi Jin

2018-03-01

Using land use data in the year 1995, 2005 and 2014, this study estimated the ecosystem service value (ESV) in each county located in the middle reach of Yangtze River and analyzed its spatiotemporal variation features and terrain gradient effects based on "the equivalent value per unit area of ecosystem services in China". The results showed that ESV in the middle reach of Yangtze River was generally higher in mountainous area but lower in plain region, with an obvious terrain gradient effect. Specifically, the relationship of the relief degree of land surface (RDLS) and the ESV showed significant logarithm function at county scale with a high curve fitting degree of 0.53. The ESV increased from 400.35×10 4 yuan·km -2 to 554.57×10 4 yuan·km -2 with the increasing RDLS (grade 1-5) in 2014. During 1995-2004, the ecosystem service value variation changed from decreasing to stable with the increases of the RDLS. With a perspective of ecosystem service values, the value of food production and waste treatment service value decreased with the increase of the RDLS, while the others increased in general, such as the production of raw materials and gas regulation service value, because of the influences of dynamic land use structure in varied topography and distinct dominant ecosystem services from different land types.

Phenomena and characteristics of barrier river reaches in the middle and lower Yangtze River, China

NASA Astrophysics Data System (ADS)

You, Xingying; Tang, Jinwu

2017-06-01

Alluvial river self-adjustment describes the mechanism whereby a river that was originally in an equilibrium state of sediment transport encounters some disturbance that destroys the balance and results in responses such as riverbed deformation. A systematic study of historical and recent aerial photographs and topographic maps in the Middle and Lower Reaches of the Yangtze River (MLYR) shows that river self-adjustment has the distinguishing feature of transferring from upstream to downstream, which may affect flood safety, waterway morphology, bank stability, and aquatic environmental safety over relatively long reaches downstream. As a result, it is necessary to take measures to control or block this transfer. Using the relationship of the occurrence time of channel adjustments between the upstream and downstream, 34 single-thread river reaches in the MLYR were classified into four types: corresponding, basically corresponding, basically not corresponding, not corresponding. The latter two types, because of their ability to prevent upstream channel adjustment from transferring downstream, are called barrier river reaches in this study. Statistics indicate that barrier river reaches are generally single thread and slightly curved, with a narrow and deep cross-sectional morphology, and without flow deflecting nodes in the upper and middle parts of reaches. Moreover, in the MLYR, barrier river reaches have a hydrogeometric coefficient of {<}{4}, a gradient {>}1.2‱, a silty clay content of the concave bank {>}{9.5}%, and a median diameter of the bed sediment {>}{0.158} mm. The barrier river reach mechanism lies in that can effectively centralise the planimetric position of the main stream from different upstream directions, meaning that no matter how the upper channel adjusts, the main stream shows little change, providing relatively stable inflow conditions for the lower reaches. Regarding river regulation, it is necessary to optimise the benefits of barrier river

Distribution, sources and ecological risk assessment of PAHs in surface sediments from the Luan River Estuary, China.

PubMed

Zhang, Daolai; Liu, Jinqing; Jiang, Xuejun; Cao, Ke; Yin, Ping; Zhang, Xunhua

2016-01-15

The distribution, sources and risk assessment of 16 polycyclic aromatic hydrocarbons (PAHs) of surface sediments in the Luan River Estuary, China, have been investigated in the research. The results indicated that the total concentrations of 16 PAHs in surface sediments of the Luan River Estuary ranged from 5.1 to 545.1 ng g(-1)dw with a mean value of 120.8 ng g(-1)dw, which is relatively low in comparison with other estuaries around the world. The PAHs in the study area were mainly originated from pyrogenic sources. Besides, PAHs may be contaminated by petrogenic PAHs as indicated by the selected ratios of PAHs, the 2-tailed Pearson correlation analysis and principal components analysis at different sites. The result of the ecological risk assessment shows little negative effect for most individual PAHs in surface sediments of the Luan River Estuary, China. Copyright © 2015 Elsevier Ltd. All rights reserved.

Aquatic ecology of the Elwha River estuary prior to dam removal: Chapter 7 in Coastal habitats of the Elwha River, Washington--biological and physical patterns and processes prior to dam removal

USGS Publications Warehouse

Duda, Jeffrey J.; Beirne, Matthew M.; Larsen, Kimberly; Barry, Dwight; Stenberg, Karl; McHenry, Michael L.; Duda, Jeffrey J.; Warrick, Jonathan A.; Magirl, Christopher S.

2011-01-01

The removal of two long-standing dams on the Elwha River in Washington State will initiate a suite of biological and physical changes to the estuary at the river mouth. Estuaries represent a transition between freshwater and saltwater, have unique assemblages of plants and animals, and are a critical habitat for some salmon species as they migrate to the ocean. This chapter summarizes a number of studies in the Elwha River estuary, and focuses on physical and biological aspects of the ecosystem that are expected to change following dam removal. Included are data sets that summarize (1) water chemistry samples collected over a 16 month period; (2) beach seining activities targeted toward describing the fish assemblage of the estuary and migratory patterns of juvenile salmon; (3) descriptions of the aquatic and terrestrial invertebrate communities in the estuary, which represent an important food source for juvenile fish and are important water quality indicators; and (4) the diet and growth patterns of juvenile Chinook salmon in the lower Elwha River and estuary. These data represent baseline conditions of the ecosystem after nearly a century of changes due to the dams and will be useful in monitoring the changes to the river and estuary following dam removal.

Biofilms as a sink for antibiotic resistance genes (ARGs) in the Yangtze Estuary

DOE Office of Scientific and Technical Information (OSTI.GOV)

Guo, Xing-pan; Yang, Yi; Lu, Da-pei

Biofilms are ubiquitous throughout aquatic environments and they are thought to promote the acquisition and dissemination of antibiotic resistant genes (ARGs). This study focused on the occurrence and distribution of five types of ARG in naturally-occurring biofilms, in comparison to associated sediment and water samples, from the Yangtze Estuary, which borders the meta-city of Shanghai, China. The detection frequency and abundances of most ARGs showed the following order: biofilm > sediment > water, which can be attributed to a high level of antibiotics and metals that can accelerate the generation and propagation of ARGs in biofilms. Most of ARG abundancesmore » were contributed by extracellular DNA (eDNA) in biofilm and sediment samples. ARGs (sul1, sul2, tetAandtetW) in eDNA were significantly correlated with TOC in both biofilm and sediment samples. Furthermore, both intracellular DNA-associated ARGs per gram of microbial biomass carbon (MBC) and eDNA-associated ARGs per gram of non-MBC and were higher in biofilms than sediments, and the partitioning coefficients of ARGs in eDNA between biofilm and water were higher than those between sediment and water. Our results provide new insight for evaluating the occurrence and abundance of ARGs in aquatic environments, confirming that biofilms are a significant sink for ARGs in the estuarine environment.« less

Sediment Transport at River Lima Estuary: Developing a Sound Methodology to Assess Sediment River Basin Input to an Erosion Prone Coast (NW Iberian Peninsula)

NASA Astrophysics Data System (ADS)

Pinho, J.; Costa, N.; Venâncio, S.; Martins, M.; Vieira, J.; Granja, H.

2016-12-01

The NW coast of Iberian Peninsula is mainly formed by rocky cliffs northern of the river Minho mouth and by narrow sandy beaches south of this river. These beaches are mainly in a sedimentary deficit status resulting from the north-south longitudinal drift driven by the dominant wave climate that acts from the NW direction. In this scenario understand and quantify river sediment inputs to the coast is crucial in order to follow a sustainable management policy to mitigate erosion impacts both in the natural and social environments. This work will present results from research conducted at rive Lima Estuary, one of the rivers flowing to the NW Iberian coast, based on both numerical modeling and field data acquisition. A hydrological model of the river basin and a detailed morphodynamic model of the estuary were implemented. Instrumentation of the estuary that is being conducted comprises traditional sensor pressures and new ones that are being designed and assembled to be installed at different measurement stations within the estuary. Modelling results for flood events showed that the river is capable of remove all the sediments that are deposited in the narrow estuarine canal located near the river mouth. Some of these sediments are immediately deposited downstream, within the interior of the harbor. Here, there is a strong possibility of silting of the river mouth and the central area of the harbor. Since the river flows during extreme events are controlled by an upstream reservoir, the capacity of the river to transport sediments to the coast was lowered during the last decades, which, moreover, requires dredging works over the years to maintain navigation depth requirements. Dredging sediments should be correctly deposited at the coast in order to properly feed the longitudinal drift, otherwise they will be out of the system, which aggravate the installed erosion tendency.

Turning the tide: effects of river inflow and tidal amplitude on sandy estuaries in laboratory landscape experiments

NASA Astrophysics Data System (ADS)

Kleinhans, Maarten; Braat, Lisanne; Leuven, Jasper; Baar, Anne; van der Vegt, Maarten; van Maarseveen, Marcel; Markies, Henk; Roosendaal, Chris; van Eijk, Arjan

2016-04-01

Many estuaries formed over the Holocene through a combination of fluvial and coastal influxes, but how estuary planform shape and size depend on tides, wave climate and river influxes remains unclear. Here we use a novel tidal flume setup of 20 m length by 3 m width, the Metronome (http://www.uu.nl/metronome), to create estuaries and explore a parameter space for the simple initial condition of a straight river in sandy substrate. Tidal currents capable of transporting sediment in both the ebb and flood phase because they are caused by periodic tilting of the flume rather than the classic method of water level fluctuation. Particle imaging velocimetry and a 1D shallow flow model demonstrate that this principle leads to similar sediment mobility as in nature. Ten landscape experiments recorded by timelapse overhead imaging and AGIsoft DEMs of the final bed elevation show that absence of river inflow leads to short tidal basins whereas even a minor discharge leads to long convergent estuaries. Estuary width and length as well as morphological time scale over thousands of tidal cycles strongly depend on tidal current amplitude. Paddle-generated waves subdue the ebb delta causing stronger tidal currents in the basin. Bar length-width ratios in estuaries are slightly larger to those in braided rivers in experiments and nature. Mutually evasive ebb- and flood-dominated channels are ubiquitous and appear to be formed by an instability mechanism with growing bar and bifurcation asymmetry. Future experiments will include mud flats and live vegetation.

Evaluation of distribution and sources of sewage molecular marker (LABs) in selected rivers and estuaries of Peninsular Malaysia.

PubMed

Magam, Sami M; Zakaria, Mohamad Pauzi; Halimoon, Normala; Aris, Ahmad Zaharin; Kannan, Narayanan; Masood, Najat; Mustafa, Shuhaimi; Alkhadher, Sadeq; Keshavarzifard, Mehrzad; Vaezzadeh, Vahab; Sani, Muhamad S A; Latif, Mohd Talib

2016-03-01

This is the first extensive report on linear alkylbenzenes (LABs) as sewage molecular markers in surface sediments collected from the Perlis, Kedah, Merbok, Prai, and Perak Rivers and Estuaries in the west of Peninsular Malaysia. Sediment samples were extracted, fractionated, and analyzed using gas chromatography mass spectrometry (GC-MS). The concentrations of total LABs ranged from 68 to 154 (Perlis River), 103 to 314 (Kedah River), 242 to 1062 (Merbok River), 1985 to 2910 (Prai River), and 217 to 329 ng g(-1) (Perak River) dry weight (dw). The highest levels of LABs were found at PI3 (Prai Estuary) due to the rapid industrialization and population growth in this region, while the lowest concentrations of LABs were found at PS1 (upstream of Perlis River). The LABs ratio of internal to external isomers (I/E) in this study ranged from 0.56 at KH1 (upstream of Kedah River) to 1.35 at MK3 (Merbok Estuary) indicating that the rivers receive raw sewage and primary treatment effluents in the study area. In general, the results of this paper highlighted the necessity of continuation of water treatment system improvement in Malaysia.

Pollutant fate and spatio-temporal variability in the choptank river estuary: Factors influencing water quality

USGS Publications Warehouse

Whitall, D.; Hively, W.D.; Leight, A.K.; Hapeman, C.J.; McConnell, L.L.; Fisher, T.; Rice, C.P.; Codling, E.; McCarty, G.W.; Sadeghi, A.M.; Gustafson, A.; Bialek, K.

2010-01-01

Restoration of the Chesapeake Bay, the largest estuary in the United States, is a national priority. Documentation of progress of this restoration effort is needed. A study was conducted to examine water quality in the Choptank River estuary, a tributary of the Chesapeake Bay that since 1998 has been classified as impaired waters under the Federal Clean Water Act. Multiple water quality parameters (salinity, temperature, dissolved oxygen, chlorophyll a) and analyte concentrations (nutrients, herbicide and herbicide degradation products, arsenic, and copper) were measured at seven sampling stations in the Choptank River estuary. Samples were collected under base flow conditions in the basin on thirteen dates between March 2005 and April 2008. As commonly observed, results indicate that agriculture is a primary source of nitrate in the estuary and that both agriculture and wastewater treatment plants are important sources of phosphorus. Concentrations of copper in the lower estuary consistently exceeded both chronic and acute water quality criteria, possibly due to use of copper in antifouling boat paint. Concentrations of copper in the upstream watersheds were low, indicating that agriculture is not a significant source of copper loading to the estuary. Concentrations of herbicides (atrazine, simazine, and metolachlor) peaked during early-summer, indicating a rapid surface-transport delivery pathway from agricultural areas, while their degradation products (CIAT, CEAT, MESA, and MOA) appeared to be delivered via groundwater transport. Some in-river processing of CEAT occurred, whereas MESA was conservative. Observed concentrations of herbicide residues did not approach established levels of concern for aquatic organisms. Results of this study highlight the importance of continued implementation of best management practices to improve water quality in the estuary. This work provides a baseline against which to compare future changes in water quality and may be used

Beluga whale summer habitat associations in the Nelson River estuary, western Hudson Bay, Canada.

PubMed

Smith, Alexander J; Higdon, Jeff W; Richard, Pierre; Orr, Jack; Bernhardt, Warren; Ferguson, Steven H

2017-01-01

To understand beluga whale (Delphinapterus leucas) estuarine use in the Nelson River estuary, southwest Hudson Bay, we recorded and examined beluga movements and habitat associations for the July through August period in 2002-2005. We compared locations of belugas fitted with satellite transmitters ("tags") (2002-2005) and aerial-surveyed (2003 and 2005) belugas for years of differing freshwater flow from the Nelson River which is influenced by hydroelectric activity. Using the beluga telemetry location data, we estimated an early August behavioral shift in beluga distribution patterns from local estuarine use to a progressively more migratory behavior away from the estuary. The timing of this shift in behavior was also apparent in results of beluga aerial surveys from the 1940s-1960s, despite environmental changes including later freeze-up and warming ocean temperatures. Overall, during the higher than average discharge ("wet") year of 2005, the three tagged belugas ranged farther from the Nelson River but not farther from the nearest shore along southwestern Hudson Bay, compared to the 10 tagged belugas tracked during the "dry" years of 2002-2004 with below average discharges. Aerial survey data for 2003 and 2005 display a similar dry vs. wet year shift in spatial patterns, with no significant change in overall density of belugas within the study area. In the Nelson estuary, proximity to the fresh-salt water mixing area may be more important than the shallow waters of the upper estuary. Killer whales (Orcinus orca) were observed in the Churchill area (200 km northwest) during each year of study, 2002-05, and belugas may benefit from the proximity to shallow estuary waters that provide protection from the larger-bodied predator. Study results contribute to an understanding of the influence of environmental variation on how and why belugas use estuaries although considerable uncertainties exist and additional research is required.

Simulation of tidal flow and circulation patterns in the Loxahatchee River Estuary, southeastern Florida

USGS Publications Warehouse

Russell, G.M.; Goodwin, C.R.

1987-01-01

Results of a two-dimensional, vertically averaged, computer simulation model of the Loxahatchee River estuary show that under typical low freshwater inflow and vertically well mixed conditions, water circulation is dominated by freshwater inflow rather than by tidal influence. The model can simulate tidal flow and circulation in the Loxahatchee River estuary under typical low freshwater inflow and vertically well mixed conditions, but is limited, however, to low-flow and well mixed conditions. Computed patterns of residual water transport show a consistent seaward flow from the northwest fork through the central embayment and out Jupiter Inlet to the Atlantic Ocean. A large residual seaward flow was computed from the North Intracoastal Waterway to the inlet channel. Although the tide produces large flood and ebb flows in the estuary, tide-induced residual transport rates are low in comparison with freshwater-induced residual transport. Model investigations of partly mixed or stratified conditions in the estuary need to await development of systems capable of simulating three-dimensional flow patterns. (Author 's abstract)

A numerical study of the plume in Cape Fear River Estuary and adjacent coastal ocean

NASA Astrophysics Data System (ADS)

Xia, M.; Xia, L.; Pietrafesa, L. J.

2006-12-01

Cape Fear River Estuary (CFRE), located in southeast North Carolina, is the only river estuary system in the state which is directly connected to the Atlantic Ocean. It is also an important nursery for economically and ecologically important juvenile fish, crabs, shrimp, and other species because of the tidal influence and saline waters. In this study, Environmental Fluid Dynamic Code (EFDC) is used to simulate the salinity plume and trajectory distribution at the mouth of the CFRE and adjacent coastal ocean. Prescribed with the climatological freshwater discharge rates in the rivers, the modeling system was used to simulate the salinity plume and trajectory distribution distribution in the mouth of the CFRE under the influence of climatological wind conditions and tidal effect. We analyzed the plume formation processes and the strong relationship between the various plume distributions with respect to the wind and river discharge in the region. The simulations also indicate that strong winds tend to reduce the surface CFRE plume size and distorting the bulge region near the estuary mouth due to enhanced wind induced surface mixing. Even moderate wind speeds could fully reverse the buoyancy-driven plume structure in CFRE under normal river discharge conditions. Tide and the river discharge also are important factors to influence the plume structure. The comparions between the distribution of salinity plume and trajectory also are discussed in the study.

Phenology of larval fish in the St. Louis River estuary

EPA Science Inventory

Little work has been done on the phenology of fish larvae in Great Lakes coastal wetlands. As part of an aquatic invasive species early detection study, we conducted larval fish surveys in the St. Louis River estuary (SLRE) in 2012 and 2013. Using multiple gears in a spatially ba...

Dynamics of the lakes in the middle and lower reaches of the Yangtze River basin, China, since late nineteenth century.

PubMed

Cui, Lijuan; Gao, Changjun; Zhao, Xinsheng; Ma, Qiongfang; Zhang, Manyin; Li, Wei; Song, Hongtao; Wang, Yifei; Li, Shengnan; Zhang, Yan

2013-05-01

The middle and lower reaches of the Yangtze River basin have the most representative and largest concentration of freshwater lakes in China. However, the size and number of these lakes have changed considerably over the past century due to the natural and anthropogenic impact. The lakes, larger than 10 km(2) in size, were chosen from relief maps and remotely sensed images in 1875, 1950, 1970, 1990, 2000, and 2008 to study the dynamics of lakes in the middle and lower reaches of the Yangtze River basin and to examine the causes and consequences of these changes. Results indicated that there was a dramatic reduction in lake areas, which decreased by 7,841.2 km(2) (42.64 %) during the study period (1875-2008), and the number of lakes in this region changed moderately. Meanwhile, a large number of lakes in the middle and lower reaches of the Yangtze River basin were directly converted into paddy fields, ponds, building lands, or other land-use types over the study period. Therefore, all kinds of lake reclamation should be identified as the major driving factors for the loss of lake in this region. Furthermore, flooding, soil erosion, and sedimentation were also the main factors which triggered lake changes in different periods. Some wetland conservation and restoration projects have been implemented since the 1970s, but they have not reversed the lake degradation. These findings were of great importance to managers involved in making policy for the conservation of lake ecosystems and the utilization of lake resources.

Nutrient Budgets and Management Actions in the Patuxent River Estuary, Maryland

EPA Science Inventory

Multi-year nitrogen (N) and phosphorus (P) budgets were developed for the Patuxent River estuary, a seasonally stratified and moderately eutrophic tributary of Chesapeake Bay. Major inputs (point, diffuse, septic and direct atmospheric) were measured for 13 years during which la...

A water-quality study of the tidal Potomac River and Estuary: An overview

USGS Publications Warehouse

Callendar, Edward; Carter, Virginia; Hahl, D.C.; Hitt, Kerie; Schultz, Barbara I.

1984-01-01

The U.S. Geological Survey began a 5-year interdisciplinary study of the tidal Potomac River and Estuary in October of 1977. The objectives of the study are: (1) to provide a basic understanding of physical, chemical, and biological processes; (2) to develop flow and transport models to predict the movement and fate of nutrients and algaes and (3) to develop efficient techniques for the study of tidal rivers and estuaries. The ultimate goal is to aid water-quality decision-making for the tidal Potomac River and Estuary. The study is being conducted by scientists from many disciplines involved in 14 interrelated studies. These scientists are addressing five major problem areas: nutrient enrichment, algal blooms, dissolved oxygen, sedimentation, and effects of water quality on living resources. Preliminary results show that treatment of sewage has reduced the concentration load of organic carbon and phosphorus below that of the 1960's and 1970's, and changed the form of dissolved nitrogen in the tidal river. Concentrations of chlorophyll a during the study period were lower than those experienced during the massive algal blooms of the 1960's. Dissolved oxygen concentrations fluctuate in response to changes in algal populations, but remain above the Environmental Protection Agency limits during the summer low-flow period. Sedimentation rates have accelerated during the past 50-70 years due to urbanization and farming. Asian clams have recently invaded the tidal river; submersed aquatic vegetation has declined since the early 1900's, but conditions may now favor its return.

Recent sediments of the St. Marks River coast, northwest Florida, a low-energy, sediment-starved estuary

DOE Office of Scientific and Technical Information (OSTI.GOV)

Highly, A.B.; Donoghue, J.F.; Garrett, C.

1994-03-01

The St. Marks river of northwest Florida drains parts of the central panhandle of northwestern Florida, and a small area in southwestern Georgia. It traverses nearly 56.3 kilometers through a watershed of 1,711 square kilometers. The slow-moving river carries little sediment and terminates in Apalachee Bay, a low-energy embayment in the northeasternmost Gulf of Mexico. The coastal region is characterized by mudflats, seagrass beds, and an absence of sandy beaches and barrier islands. Clastic sediments of the coast and shelf rest on a shallow-dipping carbonate platform. The upper surface of the platform is locally karstic. As a result, like othermore » rivers in this region of northwest Florida, the St. Marks watershed is marked by sinkholes and disappearing streams. The fact that the river travels underground through part of its lower watershed serves to trap or sieve some of its clastic load. In the estuary, the undulating karst topography causes the estuarine sediments to vary in thickness from 0 to 4+ meters. The concave shape of the coastline and its orientation with respect to prevailing winds result in low average wave energy. Sedimentation is therefore controlled by riverine and tidal forces. The relatively low energy conditions result in good preservation of the sedimentary record in the St. Marks estuary. A suite of sediment cores has been collected in the lower river, estuary and adjacent Gulf of Mexico. Lead-210 dating results indicate a slow average sedimentation rate ([approximately] 1mm/yr). Investigation of sedimentation rates and sediment characteristics over time in the St. Marks estuary indicate that sedimentologic conditions in this low-energy environment have been relatively stable during the recent geologic history of the estuary.« less

Suwannee river basin and estuary integrated science workshop: September 22-24, 2004 Cedar Key, Florida

USGS Publications Warehouse

Katz, Brian; Raabe, Ellen

2004-01-01

In response to the growing number of environmental concerns in the mostly pristine Suwannee River Basin and the Suwannee River Estuary system, the States of Florida and Georgia, the Federal government, and other local organizations have identified the Suwannee River as an ecosystem in need of protection because of its unique biota and important water resources. Organizations with vested interests in the region formed a coalition, the Suwannee Basin Interagency Alliance (SBIA), whose goals are to promote coordination in the identification, management, and scientific knowledge of the natural resources in the basin and estuary. To date, an integrated assessment of the physical, biological, and water resources has not been completed. A holistic, multi-disciplinary approach is being pursued to address the research needs in the basin and estuary and to provide supportive data for meeting management objectives of the entire ecosystem. The USGS is well situated to focus on the larger concerns of the basin and estuary by addressing specific research questions linking water supply and quality to ecosystem function and health across county and state boundaries. A strategic plan is being prepared in cooperation with Federal, State, and local agencies to identify and implement studies to address the most compelling research issues and management questions, and to conduct fundamental environmental monitoring studies. The USGS, Suwannee River Water Management District and the Florida Marine Research Institute are co-sponsoring this scientific workshop on the Suwannee River Basin and Estuary to: Discuss current and past research findings, Identify information gaps and research priorities, and Develop an action plan for coordinated and relevant research activities in the future. This workshop builds on the highly successful basin-wide conference sponsored by the Suwannee Basin Interagency Alliance that was held three years ago in Live Oak, Florida. This years workshop will focus on

In vitro assessment of thyroid hormone disrupting activities in drinking water sources along the Yangtze River.

PubMed

Hu, Xinxin; Shi, Wei; Zhang, Fengxian; Cao, Fu; Hu, Guanjiu; Hao, Yingqun; Wei, Si; Wang, Xinru; Yu, Hongxia

2013-02-01

The thyroid hormone disrupting activities of drinking water sources from the lower reaches of Yangtze River were examined using a reporter gene assay based on African green monkey kidney fibroblast (CV-1) cells. None of the eleven tested samples showed thyroid receptor (TR) agonist activity. Nine water samples exhibited TR antagonist activities with the equivalents referring to Di-n-butyl phthalate (DNBP) (TR antagonist activity equivalents, ATR-EQ(50)s) ranging from 6.92 × 10(1) to 2.85 × 10(2) μg DNBP/L. The ATR-EQ(50)s and TR antagonist equivalent ranges (ATR-EQ(30-80) ranges) for TR antagonist activities indicated that the water sample from site WX-8 posed the greatest health risks. The ATR-EQ(80)s of the water samples ranging from 1.56 × 10(3) to 6.14 × 10(3) μg DNBP/L were higher than the NOEC of DNBP. The results from instrumental analysis showed that DNBP might be responsible for the TR antagonist activities in these water samples. Water sources along Yangtze River had thyroid hormone disrupting potential. Copyright © 2012 Elsevier Ltd. All rights reserved.

Nontarget Mass Spectrometry Reveals New Perfluoroalkyl Substances in Fish from the Yangtze River and Tangxun Lake, China.

PubMed

Liu, Yanna; Qian, Manli; Ma, Xinxin; Zhu, Lingyan; Martin, Jonathan W

2018-05-15

Nontarget high-resolution mass spectrometry (Nt-HRMS) has been proven useful for the identification of unknown poly- and perfluoroalkyl substances (PFASs) in commercial products and water, but applications to biological samples are limited. China is the major PFAS-manufacturing nation; thus, here, we adapted our Nt-HRMS methods to fish collected from the Yangtze River and Tangxun Lake to discover potentially bioaccumulative PFASs in aquatic organisms destined for human consumption. In addition to traditional PFASs, over 330 other fluorinated analytes belonging to 10 classes of PFASs were detected among the pooled fish livers, including 6 sulfonate classes, 2 amine classes, 1 carboxylate class, and 1 N-heterocycle class. One class was detected in samples from both locations, 8 classes were detected exclusively in Tangxun Lake fish, and 1 class was detected exclusively in Yangtze River fish, 10 km downstream of a fluorochemical manufacturing site where we first reported these substances in wastewater 3 years ago. Overall, 4 of the PFAS classes (>165 analytes) are reported for the first time here. Wider monitoring and toxicological testing should be a priority for understanding the health risks posed to people and wildlife exposed to these substances.

A comparative study of golf industry between Yangtze River Delta, China and Central Japan

NASA Astrophysics Data System (ADS)

Yang, Yangfan; Jin, Pingbin; Gong, Huiwen

2018-03-01

As a competition event of the 2016 Olympic Game, golf sport has aroused great attention around the world. And the Yangtze River Delta(YRD) in China, has already got certain basis and qualifications of developing golf industry, but somehow far from meeting the great potential demand of the market. This research selects the Yangtze River Delta (YRD) and Central Japan (CJ), which are indifferent golf developing stages, as the objectives. Comparative studies are being carried out with an aim of revealing the discrepancies of golf industry in selected regions. The correlations between golf industry and regional economic developing level have been explored as well. Mainly based on a geographical perspective, this research presents an initial effort to combine approaches of setting comparative indexes and spatial analysis, so that golf industry of selected regions will be compared in all directions. The results reveal that great gaps exist in YRD and CJ in terms of golf construction, service, and golf consumption. Problems in developing golf industry in YRD are identified based on the empirical results. A long-term golf development in YRD that deviating from the realistic demand is attributed to both government policies and the operational principles that the market subjects hold. Based on a comparative empirical study, suggestions relating to the government as well as the market players are put forward, with an aim of guiding the golf industry to develop in a sustainable way.

Occurrence of organotins in the Yangtze River and the Jialing River in the urban section of Chongqing, China.

PubMed

Gao, Jun-Min; Zhang, Ying; Guo, Jin-Song; Jin, Fen; Zhang, Ke

2013-05-01

The occurrence of organotins in the Yangtze River and the Jialing River in the urban section of Chongqing, China and their impact on drinking water waterworks are reported in this study. Water samples were extracted by solid-phase microextraction and measured using a gas chromatograph with mass spectrometer. The results showed that the rivers studied were polluted by both butyltins and phenyltins and that the butyltin species was the dominant pollutant. Butyltins, especially monobutyltin, were detected in all 18 sampling stations, and phenyltins were detected only in 11 sampling stations. Majority of the organotins were MBTs with concentrations varying from 27.3 to 1,145.8 ng Sn L(-1). Diphenyltin and dibutyltin were the second most common with the highest levels of 113.7 and 202.5 ng Sn L(-1), respectively. Monophenyltin, tributyltin, and triphenyltin had the lowest detection rates with concentration levels of 9.7, 161.8, and 37.2 ng Sn L(-1), respectively. Some of the organotins were also detected in drinking water waterworks, which posed a threat to the water quality of Chongqing.

Foraging ecology of Caspian Terns in the Columbia River Estuary, USA

USGS Publications Warehouse

Lyons, Donald E.; Roby, D.D.; Collis, K.

2005-01-01

Comparisons were made of the foraging ecology of Caspian Terns (Sterna caspia) nesting on two islands in the Columbia River estuary using radio telemetry and observations of prey fed to chicks and mates at each colony. Early in the chick-rearing period, radio-tagged terns nesting at Rice Island (river km 34) foraged mostly in the freshwater zone of the estuary close to the colony, while terns nesting on East Sand Island (river km 8) foraged in the marine or estuarine mixing zones close to that colony. Late in the chick-rearing period, Rice Island terns moved more of their foraging to the two zones lower in the estuary, while East Sand Island terns continued to forage in these areas. Tern diets at each colony corresponded to the primary foraging zone (freshwater vs. marine/ mixing) of radio-tagged individuals: Early in chick-rearing, Rice Island terns relied heavily on juvenile salmonids (Oncorhynchus spp., 71% of identified prey), but this declined late in chick-rearing (46%). East Sand Island terns relied less on salmonids (42% and 16%, early and late in chick-rearing), and instead utilized marine fishes such as Anchovy (Engraulis mordax) and Herring (Clupea pallasi). Throughout chick-rearing, Rice Island terns foraged farther from their colony (median distance: 12.3 km during early chick-rearing and 16.9 km during late chick-rearing) than did East Sand Island terns (9.6 and 7.7 km, respectively). The study leads to the conclusion that Caspian Terns are generalist foragers and make use of the most proximate available forage fish resources when raising young.

Upstream Freshwater and Terrestrial Sources Are Differentially Reflected in the Bacterial Community Structure along a Small Arctic River and Its Estuary

PubMed Central

Hauptmann, Aviaja L.; Markussen, Thor N.; Stibal, Marek; Olsen, Nikoline S.; Elberling, Bo; Bælum, Jacob; Sicheritz-Pontén, Thomas; Jacobsen, Carsten S.

2016-01-01

Glacier melting and altered precipitation patterns influence Arctic freshwater and coastal ecosystems. Arctic rivers are central to Arctic water ecosystems by linking glacier meltwaters and precipitation with the ocean through transport of particulate matter and microorganisms. However, the impact of different water sources on the microbial communities in Arctic rivers and estuaries remains unknown. In this study we used 16S rRNA gene amplicon sequencing to assess a small river and its estuary on the Disko Island, West Greenland (69°N). Samples were taken in August when there is maximum precipitation and temperatures are high in the Disko Bay area. We describe the bacterial community through a river into the estuary, including communities originating in a glacier and a proglacial lake. Our results show that water from the glacier and lake transports distinct communities into the river in terms of diversity and community composition. Bacteria of terrestrial origin were among the dominating OTUs in the main river, while the glacier and lake supplied the river with water containing fewer terrestrial organisms. Also, more psychrophilic taxa were found in the community supplied by the lake. At the river mouth, the presence of dominant bacterial taxa from the lake and glacier was unnoticeable, but these taxa increased their abundances again further into the estuary. On average 23% of the estuary community consisted of indicator OTUs from different sites along the river. Environmental variables showed only weak correlations with community composition, suggesting that hydrology largely influences the observed patterns. PMID:27708629

Historical trends of hypoxia in Changjiang River estuary: Applications of chemical biomarkers and microfossils

USGS Publications Warehouse

Li, X.; Bianchi, T.S.; Yang, Z.; Osterman, L.E.; Allison, M.A.; DiMarco, Steven F.; Yang, G.

2011-01-01

Over the past two decades China has become the largest global consumer of fertilizers, which has enhanced river nutrient fluxes and caused eutrophication and hypoxia in the Yangtze (Changjiang) large river delta-front estuary (LDE). In this study, we utilized plant pigments, lignin-phenols, stable isotopes (δ13C and δ15N) and foraminiferal microfossils in 210Pb dated cores to examine the history of hypoxia in the Changjiang LDE. Two sediment cores were collected onboard R/V Dong Fang Hong 2 using a stainless-steel box-corer; one at a water depth of 24.7 m on Jun. 15, 2006 and the other at 52 m on Nov. 20, 2007, both in the hypoxic region off the Changjiang LDE. There has been a significant increase in the abundance of plant pigments after 1979 that are indicators of enhanced diatom and cyanobacterial abundance, which agrees with post-1980 record of increasing nutrient loads in the Changjiang River. The increased inputs of terrestrially derived materials to the LDE are largely woody plant sources and most likely due to deforestation that began in the early 1950s. However, post-1960 lignin data did not reflect enhanced loading of woody materials despite continued deforestation possibly due to increased trapping from greater dam construction, a reduction of deforestation in the drainage basin since the last 1990s, and soil conservation practices. The lack of linkages between bulk indices (stable isotopes, % OC, molar C/N ratios) and microfossil/chemical biomarkers may reflect relative differences in the amount of carbon tracked by these different proxies. Although NO3− is likely responsible for most of the changes in phytoplankton production (post 1970s), historical changes in N loading from the watershed and hypoxia on the LDE shelf may not be as well linked in East China Sea (ECS) sediments due to possible denitrification/ammonification processes; finally, increases in low-oxygen tolerant foraminiferal microfossils indicate there has been an increase in the

[Surveillance and risk assessment system of schistosomiasis in Jiangsu Province Ⅲ Risk of schistosomiasis transmission in the area along the Yangtze River in Yangzhou City].

PubMed

Yin-Ping, Zuo; Dao-Jian, Zhu; Guang-Lin, Du; Kai, Tang; Yu-Cai, Ma; Zheng-Qiu, Zhang; Shao-Zhou, Chen; Fubiao, Wang; Hong-Ping, Tang; Jin, Zhang; Le-Ping, Sun

2016-08-02

To evaluate the potential risk of schistosomiasis transmission in the area along the Yangtze River in Yangzhou City, so as to provide evidences for establishing a post-transmission surveillance system for schistosomiasis in marshland regions. The water infectivity, floating boatmen and fishermen infection, reservoir host infection and wild feces contamination were investigated in five districts/counties along the Yangtze River in Yangzhou City, including Guangling, Hanjiang, Jiangdu, Yizheng and Development Zone, and the transmission factors and risky characteristics were assessed after interruption of schistosomiasis transmission in marshland regions. A total of 15 key water regions were identified in the area along the Yangtze River in Yangzhou City in 2015. A total of 1 500 sentinel mice were placed, after breeding, their overall survival rate was 99.33%; 1 490 were dissected, with no schistosome infection. Of the 5 576 floating boatmen and fishermen examined, no schistosome infection was observed, and among the 3 566 domestic animals (including 171 cattle, 1 895 sheep and 1 500 pigs), no infections were detected. During the period between January and March, 2016, there were 3 200 mouse traps placed on 8 marshlands, and 62 wild mice were captured from 6 marshlands, with a capture rate of 1.94%, and no schistosomeinfected wild mice were seen. In addition, there were 35 pieces of fresh wild feces captured from 7 marshlands, including 11 pieces of bovine feces (31.43%), 17 pieces of sheep feces (48.57%), 2 pieces of dog feces (5.71%) and 5 pieces of other feces (14.29%), and no infections were detected. There is a low risk of schistosomiasis transmission in the area along the Yangtze River in Yangzhou City. However, the contamination of feces from bovine and sheep that are freely pastured on marshlands is a big threat to schistosomiasis control.

The formation mechanisms of turbidity maximum in the Pearl River estuary, China.

PubMed

Wai, O W H; Wang, C H; Li, Y S; Li, X D

2004-03-01

The formation and dynamics of turbidity maxima (TM) in the Pearl River estuary (PRE) are not well understood but the existence of TM in the estuary have great potential engineering and environmental impacts. Based on the measurements of two large-scale field surveys conducted in the wet season of 1978 (July of 1978) and the dry season of 1979 (March of 1979), the existence and seasonal variations of TM in the PRE focusing on the two major natural navigation channels have been studied. The sediment transport fluxes over two consecutive tidal cycles have been analyzed in detail. The analysis results reveal that the formation mechanisms of TM in the estuary are rather complex. In general, gravitational circulation, tidal trapping, and sediment resuspension and deposition processes are the primary TM formation mechanisms in the PRE. The clockwise back flow pattern around Lingding Island also leads to the formation of TM in the West channel of the PRE. The occurrence of TM far upstream of the salt water wedge is the result of the complex hydrodynamic and sediment transport processes generated by the runoff of the major rivers.

Hydrologic data summary for the St. Lucie River Estuary, Martin and St. Lucie Counties, Florida, 1998-2001

USGS Publications Warehouse

Byrne, Michael J.; Patino, Eduardo

2004-01-01

A hydrologic analysis was made at three canal sites and four tidal sites along the St. Lucie River Estuary in southeastern Florida from 1998 to 2001. The data included for analysis are stage, 15-minute flow, salinity, water temperature, turbidity, and suspended-solids concentration. During the period of record, the estuary experienced a drought, major storm events, and high-water discharge from Lake Okeechobee. Flow mainly occurred through the South Fork of the St. Lucie River; however, when flow increased through control structures along the C-23 and C-24 Canals, the North Fork was a larger than usual contributor of total freshwater inflow to the estuary. At one tidal site (Steele Point), the majority of flow was southward toward the St. Lucie Inlet; at a second tidal site (Indian River Bridge), the majority of flow was northward into the Indian River Lagoon. Large-volume stormwater discharge events greatly affected the St. Lucie River Estuary. Increased discharge typically was accompanied by salinity decreases that resulted in water becoming and remaining fresh throughout the estuary until the discharge events ended. Salinity in the estuary usually returned to prestorm levels within a few days after the events. Turbidity decreased and salinity began to increase almost immediately when the gates at the control structures closed. Salinity ranged from less than 1 to greater than 35 parts per thousand during the period of record (1998-2001), and typically varied by several parts per thousand during a tidal cycle. Suspended-solids concentrations were observed at one canal site (S-80) and two tidal sites (Speedy Point and Steele Point) during a discharge event in April and May 2000. Results suggest that most deposition of suspended-solids concentration occurs between S-80 and Speedy Point. The turbidity data collected also support this interpretation. The ratio of inorganic to organic suspended-solids concentration observed at S-80, Speedy Point, and Steele Point

Sediment accumulation and mixing in the Penobscot River and estuary, Maine.

PubMed

Yeager, K M; Schwehr, K A; Schindler, K J; Santschi, P H

2018-04-16

Mercury (Hg) was discharged in the late 1960s into the Penobscot River by the Holtra-Chem chlor-alkali production facility, which was in operation from 1967 to 2000. To assess the transport and distribution of total Hg, and recovery of the river and estuary system from Hg pollution, physical and radiochemical data were assembled from sediment cores collected from 58 of 72 coring stations sampled in 2009. These stations were located throughout the lower Penobscot River, and included four principal study regions, the Penobscot River (PBR), Mendall Marsh (MM), the Orland River (OR), and the Penobscot estuary (ES). To provide the geochronology required to evaluate sedimentary total Hg profiles, 58 of 72 sediment cores were dated using the atmospheric radionuclide tracers 137 Cs, 210 Pb, and 239,240 Pu. Sediment cores were assessed for depths of mixing, and for the determination of sediment accumulation rates using both geochemical (total Hg) and radiochemical data. At most stations, evidence for significant vertical mixing, derived from profiles of 7 Be (where possible) and porosity, was restricted to the upper ~1-3cm. Thus, historic profiles of both total Hg and radionuclides were only minimally distorted, allowing a reconstruction of their depositional history. The pulse input tracers 137 Cs and 239,240 Pu used to assess sediment accumulation rates agreed well, while the steady state tracer 210 Pb exhibited weaker agreement, likely due to irregular lateral sediment inputs. Copyright © 2018. Published by Elsevier B.V.

Spatial patterns of pharmaceuticals and wastewater tracers in the Hudson River Estuary.

PubMed

Cantwell, Mark G; Katz, David R; Sullivan, Julia C; Shapley, Daniel; Lipscomb, John; Epstein, Jennifer; Juhl, Andrew R; Knudson, Carol; O'Mullan, Gregory D

2018-06-15

The widespread use of pharmaceuticals by human populations results in their sustained discharge to surface waters via wastewater treatment plants (WWTPs). In this study, 16 highly prescribed pharmaceuticals were quantified along a 250 km transect of the Hudson River Estuary and New York Harbor to describe their sources and spatial patterns. Sampling was conducted over two dry weather periods in May and July 2016, at 72 sites which included mid-channel and nearshore sites, as well as locations influenced by tributaries and WWTP outfalls. The detection frequency of the study pharmaceuticals was almost identical between the May and July sampling periods at 55% and 52%, respectively. Six pharmaceuticals were measurable at 92% or more of the sites during both sampling periods, illustrating their ubiquitous presence throughout the study area. Individual pharmaceutical concentrations were highly variable spatially, ranging from non-detect to 3810 ng/L during the study. Major factors controlling concentrations were proximity and magnitude of WWTP discharges, inputs from tributaries and tidal mixing. Two compounds, sucralose and caffeine, were evaluated as tracers to identify wastewater sources and assess pharmaceutical behavior. Sucralose was useful in identifying wastewater inputs to the river and concentrations showed excellent correlations with numerous pharmaceuticals in the study. Caffeine-sucralose ratios showed potential in identifying discharges of untreated wastewater occurring during a combined sewage overflow event. Many of the study pharmaceuticals were present throughout the Hudson River Estuary as a consequence of sustained wastewater discharge. Whereas some concentrations were above published effects levels, a more complete risk assessment is needed to understand the potential for ecological impacts due to pharmaceuticals in the Hudson River Estuary. Published by Elsevier Ltd.

Hyperspectral Imaging of River Systems

DTIC Science & Technology

2010-09-30

98) Prescribed by ANSI Std Z39-18 2 2. As soon as it is available we will collect HICOTM data for the Yangtze River and adjacent coastal...the Yangtze and other river systems. The goal is to validate our algorithms and to further our understanding of this important river and the East...For the past year we have been collecting HICOTM data for the Columbia (Fig. 3) and Yangtze Rivers (Fig. 4). There are many constraints on data

An integrated environmental improvement of marshlands: impact on control and elimination of schistosomiasis in marshland regions along the Yangtze River, China.

PubMed

Sun, Le-Ping; Wang, Wei; Zuo, Yin-Ping; Zhang, Zheng-Qiu; Hong, Qing-Biao; Yang, Guo-Jing; Zhu, Hong-Ru; Liang, You-Sheng; Yang, Hai-Tao

2017-03-22

Schistosomiasis is a global snail-transmitted infectious disease of poverty. Transmission control had been achieved in China in 2015 after the control efforts for over 60 years. Currently, the remaining core regions endemic for Schistosoma japonicum are mainly located in the marshland and lake regions along the Yangtze River basin. During the period from 2001 through 2015, an integrated environmental improvement of the marshlands was carried out through the implementation of industrial, agricultural and resources development projects in Yizheng County along the Yangtze River. S. japonicum infection in humans, livestock and snails was estimated by serology, stool examination, hatching technique and microscopy during the 15-year study period to evaluate the effect of the integrated environmental improvement on control and elimination of schistosomiasis. A 0.05% overall rate of S. japonicum infection was observed in snails during the 15-year study period, and no infected snails were detected since 2012. The overall prevalence of S. japonicum infection was 0.09% in humans during the study period, and no human infection was found since 2012. In addition, only 13 bovines were identified with S. japonicum infection in 2003 during the 15-year study period, and since 2004, no infection was found in livestock. The results of the present study demonstrate that the implementation of industrial, agricultural and water resources development projects, not only alters snail habitats in marshland regions, and promotes local economic development, which appears a win-to-win strategy to block the transmission of S. japonicum and accelerate socio-economic development along the Yangtze River.

Dependence of Wetland Vegetation on Hydrological Regime in a Large Floodplain Lake (Poyang Lake) in the Middle Yangtze River

NASA Astrophysics Data System (ADS)

Zhang, Q.; Tan, Z.; Xu, X.

2017-12-01

Exemplified in the Yangtze River floodplain lake, Poyang Lake, investigations were carried out to examine the dependence of vegetation on hydrological variables. The Lake is one of the few lakes that remain naturally connected to the Yangtze River. The Lake surface expanses to 4000 km2 in wet seasons, and reduces to less than 1000 km2 in dry seasons, creating some 3000 km2 vital wetland habitats for many animals. Remote sensing was used to obtain the spatial distribution of wetland vegetations. A lake hydrodynamic model using MIKE 21 was employed to determine the variability of wetland inundation. In-situ high time frequency observations of climate, soil moisture, and groundwater depth were also conducted in a typical wetland transect of 1 km long. Vegetations were sampled periodically to obtain species composition, diversity and biomass. Results showed that the spatial distribution of vegetation highly depended on the inundation duration and depth. Optimal hydrological variables existed for the typical vegetations in Poyang Lake wetland. Numerical simulations using HYDRUS-1D further demonstrated that both groundwater depth and soil moisture had significant effects on the growth of vegetation and the water demand in terms of transpiration, even in a wet climate zone such as middle Yangtze River. It was found that the optimal groundwater depths existed for both above- and belowground biomass. Simulation scenarios indicated that climate changes and human modification of hydrology would affect the water usage of vegetation and may cause a strategic adaptation of the vegetation to the stressed hydrological conditions. The study revealed new knowledge on the high dependence of wetland vegetation on both surface water regime and groundwater depths, in wet climate zone. Outcomes of this study may provide support for an integrated management of balancing water resources development and wetland sustainability maintenance in Poyang Lake, and other floodplain wetlands, with

Quantitative tolerance values for common stream benthic macroinvertebrates in the Yangtze River Delta, Eastern China.

PubMed

Qin, Chun-Yan; Zhou, Jin; Cao, Yong; Zhang, Yong; Hughes, Robert M; Wang, Bei-Xin

2014-09-01

Aquatic organisms' tolerance to water pollution is widely used to monitor and assess freshwater ecosystem health. Tolerance values (TVs) estimated based on statistical analyses of species-environment relationships are more objective than those assigned by expert opinion. Region-specific TVs are the basis for developing accurate bioassessment metrics particularly in developing countries, where both aquatic biota and their responses to human disturbances have been poorly documented. We used principal component analysis to derive a synthetic gradient for four stressor variables (total nitrogen, total phosphorus, dissolved oxygen, and % silt) based on 286 sampling sites in the Taihu Lake and Qiantang River basins (Yangtze River Delta), China. We used the scores of taxa on the first principal component (PC1), which explained 49.8% of the variance, to estimate the tolerance values (TV(r)) of 163 macroinvertebrates taxa that were collected from at least 20 sites, 81 of which were not included in the Hilsenhoff TV lists (TV(h)) of 1987. All estimates were scaled into the range of 1-10 as in TV(h). Of all the taxa with different TVs, 46.3% of TV(r) were lower and 52.4% were higher than TV(h). TV(r) were significantly (p < 0.01, Fig. 2), but weakly (r(2) = 0.34), correlated with TVh. Seven biotic metrics based on TVr were more strongly correlated with the main stressors and were more effective at discriminating references sites from impacted sites than those based on TV(h). Our results highlight the importance of developing region-specific TVs for macroinvertebrate-based bioassessment and to facilitate assessment of streams in China, particularly in the Yangtze River Delta.

Regional variations of organophosphorus flame retardants - Fingerprint of large river basin estuaries/deltas in Europe compared with China.

PubMed

Wolschke, Hendrik; Sühring, Roxana; Massei, Riccardo; Tang, Jianhui; Ebinghaus, Ralf

2018-05-01

This study reports the occurrence and distribution of organophosphorus flame retardants and plasticizer (OPEs) in sediments of eight large river basin estuaries and deltas across Europe. A robust and sensitive OPE analysis method was developed through the application of an in-cell clean-up in an accelerated solvent extraction and the use of an GC-MSMS System for instrumental analyses. OPEs were detected in all sediment samples with sum concentrations of up to 181 ng g -1 dw. A fingerprinting method was used to identify river specific pattern to compare river systems. The estuaries and deltas were chosen to have a conglomerate print of the whole river. The results are showing very similar OPE patterns across Europe with minor differences driven by local industrial input. The European estuary concentrations and patterns were compared with OPEs detected in the Xiaoquing River in China, as an example for a region with other production, usage and legislative regulations. The Chinese fingerprint differed significant from the overall European pattern. Copyright © 2018 Elsevier Ltd. All rights reserved.

Beluga whale summer habitat associations in the Nelson River estuary, western Hudson Bay, Canada

PubMed Central

Smith, Alexander J.; Higdon, Jeff W.; Richard, Pierre; Orr, Jack; Bernhardt, Warren

2017-01-01

To understand beluga whale (Delphinapterus leucas) estuarine use in the Nelson River estuary, southwest Hudson Bay, we recorded and examined beluga movements and habitat associations for the July through August period in 2002–2005. We compared locations of belugas fitted with satellite transmitters (“tags”) (2002–2005) and aerial-surveyed (2003 and 2005) belugas for years of differing freshwater flow from the Nelson River which is influenced by hydroelectric activity. Using the beluga telemetry location data, we estimated an early August behavioral shift in beluga distribution patterns from local estuarine use to a progressively more migratory behavior away from the estuary. The timing of this shift in behavior was also apparent in results of beluga aerial surveys from the 1940s–1960s, despite environmental changes including later freeze-up and warming ocean temperatures. Overall, during the higher than average discharge (“wet”) year of 2005, the three tagged belugas ranged farther from the Nelson River but not farther from the nearest shore along southwestern Hudson Bay, compared to the 10 tagged belugas tracked during the “dry” years of 2002–2004 with below average discharges. Aerial survey data for 2003 and 2005 display a similar dry vs. wet year shift in spatial patterns, with no significant change in overall density of belugas within the study area. In the Nelson estuary, proximity to the fresh-salt water mixing area may be more important than the shallow waters of the upper estuary. Killer whales (Orcinus orca) were observed in the Churchill area (200 km northwest) during each year of study, 2002–05, and belugas may benefit from the proximity to shallow estuary waters that provide protection from the larger-bodied predator. Study results contribute to an understanding of the influence of environmental variation on how and why belugas use estuaries although considerable uncertainties exist and additional research is required. PMID

The faucet snail (Bithynia tentaculata) invades the St. Louis River Estuary

EPA Science Inventory

The European-origin faucet snail (Bithynia tentaculata) now numbers among the aquatic invasive species present in the St. Louis River Estuary. This snail has been in the lower Great Lakes since the early 20th century but is new to the Lake Superior basin. We found faucet snails...

Sediment discharge into a subsiding Louisiana deltaic estuary through a Mississippi River diversion

USGS Publications Warehouse

Snedden, G.A.; Cable, J.E.; Swarzenski, C.; Swenson, E.

2007-01-01

Wetlands of the Mississippi River deltaic plain in southeast Louisiana have been hydrologically isolated from the Mississippi River by containment levees for nearly a century. The ensuing lack of fluvial sediment inputs, combined with natural submergence processes, has contributed to high coastal land loss rates. Controlled river diversions have since been constructed to reconnect the marshes of the deltaic plain with the river. This study examines the impact of a pulsed diversion management plan on sediment discharge into the Breton Sound estuary, in which duplicate 185 m3 s-1-diversions lasting two weeks each were conducted in the spring of 2002 and 2003. Sediment delivery during each pulse was highly variable (11,300-43,800 metric tons), and was greatest during rising limbs of Mississippi River flood events. Overland flow, a necessary transport mechanism for river sediments to reach the subsiding backmarsh regions, was induced only when diversion discharge exceeded 100 m3 s-1. These results indicate that timing and magnitude of diversion events are both important factors governing marsh sediment deposition in the receiving basins of river diversions. Though the diversion serves as the primary source of river sediments to the estuary, the inputs observed here were several orders of magnitude less than historical sediment discharge through crevasses and uncontrolled diversions in the region, and are insufficient to offset present rates of relative sea level rise. ?? 2006 Elsevier Ltd. All rights reserved.

The response of grain production to changes in quantity and quality of cropland in Yangtze River Delta, China.

PubMed

Liu, Guilin; Zhang, Luocheng; Zhang, Qian; Musyimi, Zipporah

2015-02-01

Cropland in Yangtze River Delta has declined drastically since economic reforms in 1978 that led to rapid economic development. Such cropland loss due to population growth has led to a decline in grain production. This study aimed at analyzing the impact of land use changes on grain production. To achieve this, the spatiotemporal dynamics of cropland during 1980-2010 were analyzed. Irrigation and soil fertility data were used as additional lines of evidence. Cropland loss had negative impacts on grain production. About 80 and 66% of grain production decreased during 1980-2005 and 2005-2010 respectively. This decline was attributed to the conversion of cropland to built-up areas. Abandoned cropland areas were mainly concentrated in regions with high irrigation capability and high soil fertility, while cropland reclamation was mainly in areas with low irrigation and soil fertility, implying that, although cropland was reclaimed, production remained low. The decline in cropland area has reinforced the chronic food insecurity in Yangtze River Delta. This study demonstrated the response of grain production to the changes in cropland quantity and quality. It also provides scientific evidence for decision makers to protect cropland and enhance grain production. © 2014 Society of Chemical Industry.

Impact of the Clean Water Act on the levels of toxic metals in urban estuaries: The Hudson River estuary revisited

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sanudo-Wilhelmy, S.A.; Gill, G.A.

1999-10-15

To establish the impact of the Clean Water Act on the water quality of urban estuaries, dissolved trace metals and phosphate concentrations were determined in surface waters collected along the Hudson River estuary between 1995 and 1997 and compared with samples collected in the mid-1970s by Klinkhammer and Bender. The median concentrations along the estuary have apparently declined 36--56% for Cu, 55--89% for Cd, 53--85% for Ni, and 53--90% for Zn over a period of 23 years. These reductions appear to reflect improvements in controlling discharges from municipal and industrial wastewater treatment plants since the Clean Water Act was enactedmore » in 1972. In contrast, levels of dissolved nutrients (PO{sub 4}) have remained relatively constant during the same period of time, suggesting that wastewater treatment plant improvements in the New York/New Jersey Metropolitan area have not been as effective at reducing nutrient levels within the estuary. While more advanced wastewater treatment could potentially reduce the levels of Ag and PO{sub 4} along the estuary, these improvements would have a more limited effect on the levels of other trace metals.« less

Estuarine research; an annotated bibliography of selected literature, with emphasis on the Hudson River estuary, New York and New Jersey

USGS Publications Warehouse

Embree, William N.; Wiltshire, Denise A.

1978-01-01

Abstracts of 177 selected publications on water movement in estuaries, particularly the Hudson River estuary, are compiled for reference in Hudson River studies. Subjects represented are the hydraulic, chemical, and physical characteristics of estuarine waters, estuarine modeling techniques, and methods of water-data collection and analysis. Summaries are presented in five categories: Hudson River estuary studies; hydrodynamic-model studies; water-quality-model studies; reports on data-collection equipment and methods; and bibliographies, literature reviews, conference proceedings, and textbooks. An author index is included. Omitted are most works published before 1965, environmental-impact statements, theses and dissertations, policy or planning reports, regional or economic reports, ocean studies, studies based on physical models, and foreign studies. (Woodard-USGS)

Distribution and abundance of American eels in the White Oak River estuary, North Carolina

USGS Publications Warehouse

Hightower, J.E.; Nesnow, C.

2006-01-01

Apparent widespread declines in abundance of Anguilla rostrata (American eel) have reinforced the need for information regarding its life history and status. We used commercial eel pots and crab (peeler) pots to examine the distribution, condition, and abundance of American eels within the White Oak River estuary, NC, during summers of 2002-2003. Catch of American eels per overnight set was 0.35 (SE = 0.045) in 2002 and 0.49 (SE = 0.044) in 2003. There was not a significant linear relationship between catch per set and depth in 2002 (P = 0.31, depth range 0.9-3.4 m) or 2003 (P = 0.18, depth range 0.6-3.4 m). American eels from the White Oak River were in good condition, based on the slope of a length-weight relationship (3.41) compared to the median slope (3.15) from other systems. Estimates of population density from grid sampling in 2003 (300 mm and larger: 4.0-13.8 per ha) were similar to estimates for the Hudson River estuary, but substantially less than estimates from other (smaller) systems including tidal creeks within estuaries. Density estimates from coastal waters can be used with harvest records to examine whether overfishing has contributed to the recent apparent declines in American eel abundance.

Foraging patterns of Caspian terns and double-crested cormorants in the Columbia River estuary

USGS Publications Warehouse

Lyons, Donald E.; Roby, D.D.; Collis, K.

2007-01-01

We examined spatial and temporal foraging patterns of Caspian terns and double-crested cormorants nesting in the Columbia River estuary, to potentially identify circumstances where juvenile salmonids listed under the U.S. Endangered Species Act might be more vulnerable to predation by these avian piscivores. Data were collected during the 1998 and 1999 breeding seasons, using point count surveys of foraging birds at 40 sites along the river's banks, and using aerial strip transect counts throughout the estuary for terns. In 1998, terns selected tidal flats and sites with roosting beaches nearby for foraging, making greater use of the marine/mixing zone of the estuary later in the season, particularly areas near the ocean jetties. In 1999, cormorants selected foraging sites in freshwater along the main channel with pile dikes present, particularly early in the season. Foraging trends in the other year for each species were generally similar to the above but usually not significant. During aerial surveys we observed 50% of foraging and commuting terns within 8 km of the Rice Island colony, and ??? 5% of activity occurred ??? 27 km from this colony in both years. Disproportionately greater cormorant foraging activity at pile dikes may indicate greater vulnerability of salmonids to predation at those features. Colony relocations to sites at sufficient distance from areas of relatively high salmonid abundance may be a straightforward means of reducing impacts of avian predation on salmonids than habitat alterations within the Columbia River estuary, at least for terns. ?? 2007 by the Northwest Scientific Association. All rights reserved.

Genome Sequence of the Freshwater Yangtze Finless Porpoise.

PubMed

Yuan, Yuan; Zhang, Peijun; Wang, Kun; Liu, Mingzhong; Li, Jing; Zheng, Jingsong; Wang, Ding; Xu, Wenjie; Lin, Mingli; Dong, Lijun; Zhu, Chenglong; Qiu, Qiang; Li, Songhai

2018-04-16

The Yangtze finless porpoise ( Neophocaena asiaeorientalis ssp. asiaeorientalis ) is a subspecies of the narrow-ridged finless porpoise ( N. asiaeorientalis ). In total, 714.28 gigabases (Gb) of raw reads were generated by whole-genome sequencing of the Yangtze finless porpoise, using an Illumina HiSeq 2000 platform. After filtering the low-quality and duplicated reads, we assembled a draft genome of 2.22 Gb, with contig N50 and scaffold N50 values of 46.69 kilobases (kb) and 1.71 megabases (Mb), respectively. We identified 887.63 Mb of repetitive sequences and predicted 18,479 protein-coding genes in the assembled genome. The phylogenetic tree showed a relationship between the Yangtze finless porpoise and the Yangtze River dolphin, which diverged approximately 20.84 million years ago. In comparisons with the genomes of 10 other mammals, we detected 44 species-specific gene families, 164 expanded gene families, and 313 positively selected genes in the Yangtze finless porpoise genome. The assembled genome sequence and underlying sequence data are available at the National Center for Biotechnology Information under BioProject accession number PRJNA433603.

Genome Sequence of the Freshwater Yangtze Finless Porpoise

PubMed Central

Yuan, Yuan; Zhang, Peijun; Wang, Kun; Liu, Mingzhong; Li, Jing; Zheng, Jinsong; Wang, Ding; Xu, Wenjie; Lin, Mingli; Dong, Lijun; Zhu, Chenglong; Qiu, Qiang

2018-01-01

The Yangtze finless porpoise (Neophocaena asiaeorientalis ssp. asiaeorientalis) is a subspecies of the narrow-ridged finless porpoise (N. asiaeorientalis). In total, 714.28 gigabases (Gb) of raw reads were generated by whole-genome sequencing of the Yangtze finless porpoise, using an Illumina HiSeq 2000 platform. After filtering the low-quality and duplicated reads, we assembled a draft genome of 2.22 Gb, with contig N50 and scaffold N50 values of 46.69 kilobases (kb) and 1.71 megabases (Mb), respectively. We identified 887.63 Mb of repetitive sequences and predicted 18,479 protein-coding genes in the assembled genome. The phylogenetic tree showed a relationship between the Yangtze finless porpoise and the Yangtze River dolphin, which diverged approximately 20.84 million years ago. In comparisons with the genomes of 10 other mammals, we detected 44 species-specific gene families, 164 expanded gene families, and 313 positively selected genes in the Yangtze finless porpoise genome. The assembled genome sequence and underlying sequence data are available at the National Center for Biotechnology Information under BioProject accession number PRJNA433603. PMID:29659530

Heavy Metal Pollution of Lakes along the Mid-Lower Reaches of the Yangtze River in China: Intensity, Sources and Spatial Patterns

PubMed Central

Zeng, Haiao; Wu, Jinglu

2013-01-01

Lakes in the middle and lower reaches of the Yangtze River form a shallow lake group unique in the World that is becoming increasingly polluted by heavy metals. Previous studies have largely focused on individual lakes, with limited exploration of the regional pattern of heavy metal pollution of the lake group in this area. This paper explores the sources, intensity and spatial patterns of heavy metal pollution of lake sediments. A total of 45 sample lakes were selected and the concentrations of key metal elements in the sediments of each lake were measured. The cluster analysis (CA), principal component analysis (PCA) and Geo-accumulation index (Ig) analysis permitted analysis of the source and pollution intensity of the target lakes. Results suggested a notable spatial variation amongst the sample lakes. Lakes in the upper part of the lower reach of the Yangtze River surrounded by typical urban landscapes were strongly or extremely polluted, with high concentrations of Pb, Zn, Cu and Cd in their sediments. This was attributed to large amount of untreated industrial discharges and municipal sewage produced within the lake catchments. In contrast, the heavy-metal pollution of lakes in the Taihu Delta area was notably lower due to industrial restructuring and implementation of effective environmental protection measures. Lakes along the middle reach of Yangtze River surrounded by agricultural areas were unpolluted to moderately polluted by heavy metals overall. Our results suggested that lakes in the central part of China require immediate attention and efforts should be made to implement management plans to prevent further degradation of water quality in these lakes. PMID:23442559

Identification of Phragmites australis and Spartina alterniflora in the Yangtze Estuary between Bayes and BP neural network using hyper-spectral data

NASA Astrophysics Data System (ADS)

Liu, Pudong; Zhou, Jiayuan; Shi, Runhe; Zhang, Chao; Liu, Chaoshun; Sun, Zhibin; Gao, Wei

2016-09-01

The aim of this work was to identify the coastal wetland plants between Bayes and BP neural network using hyperspectral data in order to optimize the classification method. For this purpose, we chose two dominant plants (invasive S. alterniflora and native P. australis) in the Yangtze Estuary, the leaf spectral reflectance of P. australis and S. alterniflora were measured by ASD field spectral machine. We tested the Bayes method and BP neural network for the identification of these two species. Results showed that three different bands (i.e., 555 nm 711 nm and 920 nm) could be identified as the sensitive bands for the input parameters for the two methods. Bayes method and BP neural network prediction model both performed well (Bayes prediction for 88.57% accuracy, BP neural network model prediction for about 80% accuracy), but Bayes theorem method could give higher accuracy and stability.

Occurrence of Cymbasoma longispinosum Bourne, 1890 in the Curuçá River estuary.

PubMed

Leite, Natália R; Pereira, Luci C C; Abrunhosa, Fernando; Pires, Marcus A B; Costa, Rauquírio M da

2010-09-01

The present work was carried out to verify the occurrence and distribution of Cymbasoma longispinosum Bourne, 1890 in a tropical Amazon estuary from North Brazil. Samplings were performed bimonthly from July/2003 to July/2004 at two different transects (Muriá and Curuçá rivers) situated along the Curuçá estuary (Pará, North Brazil). Samples were collected during neap tides via gentle (1 to 1.5 knots) 200 μm-mesh net tows from a small boat. Additional subsurface water samples were collected for the determination of environmental parameters. Males and females of Cymbasoma longispinosum were only observed during September and November/2003. The highest number of organisms was found in September/2003 at the Muriá River transect. The presence of C. longispinosum in samples obtained during September and November/2003 could probably be related to the reproductive period of this species in the studied estuary, which is directly related to the dry period in the region. The highest salinity values and the highest number of individuals observed in September/2003 corroborate with the previous assumption, since no C. longispinosum was found during the months comprising the rainy period (January to June).

Modelling of river plume dynamics in Öre estuary (Baltic Sea) with Telemac-3D hydrodynamic model

NASA Astrophysics Data System (ADS)

Sokolov, Alexander

2016-04-01

The main property of river plumes is their buoyancy, fresh water discharged by rivers is less dense than the receiving, saline waters. To study the processes of plume formation in case of river discharge into a brackish estuary where salinity is low (3.5 - 5 psu) a three dimensional hydrodynamic model was applied to the Öre estuary in the Baltic Sea. This estuary is a small fjord-like bay in the north part of the Baltic Sea. Size of the bay is about 8 by 8 km with maximum depth of 35 metres. River Öre has a small average freshwater discharge of 35 m3/s. But in spring during snowmelt the discharge can be many times higher. For example, in April 2015 the discharge increased from 8 m3/s to 160 m3/s in 18 days. To study river plume dynamics a finite element based three dimensional baroclinic model TELEMAC - 3D is used. The TELEMAC modelling suite is developed by the National Laboratory of Hydraulics and Environment (LNHE) of Electricité de France (EDF). Modelling domain was approximated by an unstructured mesh with element size varies from 50 to 500 m. In vertical direction a sigma-coordinate with 20 layers was used. Open sea boundary conditions were obtained from the Baltic Sea model HIROMB-BOOS using COPERNICUS marine environment monitoring service. Comparison of modelling results with observations obtained by BONUS COCOA project's field campaign in Öre estuary in 2015 shows that the model plausible simulate river plume dynamics. Modelling of age of freshwater is also discussed. This work resulted from the BONUS COCOA project was supported by BONUS (Art 185), funded jointly by the EU and the Swedish Research Council Formas.

Factors affecting chick provisioning by Caspian Terns nesting in the Columbia River estuary

USGS Publications Warehouse

Anderson, Scott K.; Roby, D.D.; Lyons, Donald E.; Collis, K.

2005-01-01

We investigated factors affecting chick provisioning by radio-tagged Caspian Terns (Sterna caspia) nesting in a large colony on East Sand Island in the Columbia River estuary during 2001. Caspian Tern predation on juvenile salmonids (Oncorhynchus spp.) in the estuary prompted resource managers to relocate ca. 9,000 pairs of terns nesting on Rice Island (river km 34) to East Sand Island (river km 8), where terns were expected to consume fewer salmonids in favor of marine forage fishes. This study investigated factors influencing foraging success, diet composition, and overall reproductive success at the managed Caspian Tern colony. Our results indicated that daytime colony attendance by nesting terns averaged 64% and decreased throughout the chick-rearing period, while duration of foraging trips averaged 47 min and increased during the same period; these seasonal changes were more strongly related to date than chick age. Average meal delivery rates to 2-chick broods (0.88 meals h-1) were 2.6 times greater than to 1-chick broods (0.33 meals h-1). Parents delivered more juvenile salmonids to chicks during ebb tides than flood tides, but meal delivery rates to the nest remained constant, suggesting diet composition tracks relative availability of prey species. Foraging trips resulting in delivery of juvenile salmonids averaged 68% longer than foraging trips for schooling marine forage fishes, indicating higher availability of marine prey near the colony. High availability of marine forage fish in the Columbia River estuary during 2001 was apparently responsible for high colony attendance, short foraging trips, high chick meal delivery rates, and high nesting success of Caspian Terns on East Sand Island.

Tempo-spatial dynamics of water quality and its response to river flow in estuary of Taihu Lake based on GOCI imagery.

PubMed

Du, Chenggong; Li, Yunmei; Wang, Qiao; Liu, Ge; Zheng, Zhubin; Mu, Meng; Li, Yuan

2017-12-01

Knowledge of tempo-spatial dynamics of water quality and its response to river flow is important for the management of lake water quality because river discharge associated with rainstorms can be an important source of pollutants to the estuary. Total phosphorus (TP), chlorophyll a (Chl-a), and total suspended matter (TSM) are important indexes of water quality and important factors influencing eutrophication and algal blooms. In this study, remote sensing was used to monitor these indexes to investigate the effects of river discharge on the estuary of Taihu Lake by the largest inflow river which is Chendong River using a total of 136 Geostationary Ocean Color Images (GOCI). In situ datasets collected during the four cruise experiments on Taihu Lake between 2011 and 2015 were used to develop the TP, Chl-a, and TSM inversion models based on simple empirical algorithms: 154 points for TP (mg/L), 114 for Chl-a (μg/L), and 181 for TSM (mg/L). The spatial and temporal changes of the concentration of the three parameters in the Chendong River estuary were analyzed by combining the GOCI data, the flow of the Chendong River, and meteorological data throughout the year in 2014. The several key findings are as follows: (1) In summer and autumn, TP, Chl-a, and TSM contents were significantly higher than in winter and spring. TP and Chl-a have a few similar distribution characteristics. And organic suspended matter in summer was the main reason for the increase of the TSM concentration. (2) The severe surface erosion in the rivers cannot be ignored; the high erodibility is an important factor in the increase of TP and TSM concentrations in the estuary. The concentration of the water quality parameter showed exponential decay with distance from the shore. The concentration decreased slowly after 12 km and then remained essentially constant. (3) TP content in the Chendong River estuary decreased under steady flow inputs and dramatically increased when the flow became large

Precursory strong-signal characteristics of the convective clouds of the Central Tibetan Plateau detected by radar echoes with respect to the evolutionary processes of an eastward-moving heavy rainstorm belt in the Yangtze River Basin

NASA Astrophysics Data System (ADS)

Zhao, Yang; Xu, Xiangde; Ruan, Zheng; Chen, Bin; Wang, Fang

2018-03-01

The integrated analysis of the data from a C-band frequency-modulated continuous-wave (C-FMCW) radar site in Naqu obtained during a rainstorm over the middle and lower reaches of the Yangtze River and the data concerning the three-dimensional structure of the circulation of the precipitation system that occurred over the lower reaches of the Yangtze River Basin during the Third Tibetan Plateau (TP) Atmospheric Experiment from August 15th to 19th, 2014, was carried out. The changes in the echo intensity at the C-FMCW radar site in Naqu were of regional indicative significance for the characteristics of the whole-layer apparent heat source Q1 in local areas and the region of the adjacent river source area, including the Yangtze River, Yellow River, and Lancang River (hereinafter referred to as the "source area of three rivers"), as well as to the vertical speeds due to the development of convection. This study indicates that the C-FMCW radar echo intensity of the plateau convection zone and the related power structures of the coupled dipole circulations in the middle layer of the atmosphere, as well as in the upper atmospheric level divergence and lower atmospheric level convergence, are important stimuli for convective clouds in this region. Furthermore, these radar data provided a physical image of the development and maintenance mechanisms of an eastward-moving heavy rainstorm belt. This study also shows that changes in the echo intensities at the C-FMCW radar site of Naqu can provide strong signals related to heavy rainstorm processes in the upper reaches of the Yangtze River.

Atmospheric nitrogen deposition in the Yangtze River basin: Spatial pattern and source attribution.

PubMed

Xu, Wen; Zhao, Yuanhong; Liu, Xuejun; Dore, Anthony J; Zhang, Lin; Liu, Lei; Cheng, Miaomiao

2018-01-01

The Yangtze River basin is one of the world's hotspots for nitrogen (N) deposition and likely plays an important role in China's riverine N output. Here we constructed a basin-scale total dissolved inorganic N (DIN) deposition (bulk plus dry) pattern based on published data at 100 observational sites between 2000 and 2014, and assessed the relative contributions of different reactive N (N r ) emission sectors to total DIN deposition using the GEOS-Chem model. Our results show a significant spatial variation in total DIN deposition across the Yangtze River basin (33.2 kg N ha -1 yr -1 on average), with the highest fluxes occurring mainly in the central basin (e.g., Sichuan, Hubei and Hunan provinces, and Chongqing municipality). This indicates that controlling N deposition should build on mitigation strategies according to local conditions, namely, implementation of stricter control of N r emissions in N deposition hotspots but moderate control in the areas with low N deposition levels. Total DIN deposition in approximately 82% of the basin area exceeded the critical load of N deposition for semi-natural ecosystems along the basin. On the basin scale, the dominant source of DIN deposition is fertilizer use (40%) relative to livestock (11%), industry (13%), power plant (9%), transportation (9%), and others (18%, which is the sum of contributions from human waste, residential activities, soil, lighting and biomass burning), suggesting that reducing NH 3 emissions from improper fertilizer (including chemical and organic fertilizer) application should be a priority in curbing N deposition. This, together with distinct spatial variations in emission sector contributions to total DIN deposition also suggest that, in addition to fertilizer, major emission sectors in different regions of the basin should be considered when developing synergistic control measures. Copyright © 2017. Published by Elsevier Ltd.

A monitoring study of the 1998 rainstorm along the Yangtze River of China by using TIPEX data

NASA Astrophysics Data System (ADS)

Wang, Jizhi; Yang, Yuanqin; Xu, Xiangde; Zhang, Guangzhi

2003-05-01

By using data from the Secondary Tibetan Plateau Science Experiment (TIPEX) in 1998, including enhanced soundings, surface observations, data from captive balloons, remote sensing, and Doppler radar (China and Japan cooperative study of GAME/ Tibet), a monitoring study on the generation and moving track of the cumulus convective systems over the Tibetan Plateau is made, and the relationship between the evolution of cloud systems over the Tibetan Plateau and 1998 flooding in China is studied. The results are as follows. 1) Analyzing the image animation and Hovmoller diagram of satellite TBB data shows that the rainstorms for the Yangtze River in the last ten days of July 1998 can be tracked regionally to the Tibetan Plateau. 2) For the period of cloud clusters passing through the Amdo station (18 19 July), monitoring observations by Doppler radar is made. The monitoring of radar echoes shows that the developing, eastward motion, and strengthening of the echoes can be frequently observed in the middle of the Tibetan Plateau. An integrated analysis and tracking of the generation, disappearance, development, and eastward motion of these convective systems by using multiple instruments is very valuable for diagnosing and predicting the influence of the plateau systems on the downstream weather situation. 3) The integrated analysis of space-time cross sections of the enhanced upper air and surface observations from TIPEX during the intensified observation period shows that the frequent development of convective clouds over the Tibetan Plateau is related with the quasi-stationary convergence of surface winds. The dynamic convergence of surface winds, the vertical shear in the upper air, and transportation of water vapor due to increasing humidity over the Tibetan Plateau played an important role in the developing and strengthening of rainstorms over the Yangtze River in 1998. 4) Meso-sale filtration analysis of the vertical distribution of water vapor over the Tibetan

Baseline sediment trace metals investigation: Steinhatchee River estuary, Florida, Northeast Gulf of Mexico

USGS Publications Warehouse

Trimble, C.A.; Hoenstine, R.W.; Highley, A.B.; Donoghue, J.F.; Ragland, P.C.

1999-01-01

This Florida Geological Survey/U.S. Department of the Interior, Minerals Management Service Cooperative Study provides baseline data for major and trace metal concentrations in the sediments of the Steinhatchee River estuary. These data are intended to provide a benchmark for comparison with future metal concentration data measurements. The Steinhatchee River estuary is a relatively pristine bay located within the Big Bend Wildlife Management Area on the North Central Florida Gulf of Mexico coastline. The river flows 55 km through woodlands and planted pines before emptying into the Gulf at Deadman Harbor. Water quality in the estuary is excellent at present. There is minimal development within the watershed. The estuary is part of an extensive system of marshes that formed along the Florida Gulf coast during the Holocene marine transgression. Sediment accretion rate measurements range from 1.4 to 4.1 mm/yr on the basis of lead-210 measurements. Seventy-nine short cores were collected from 66 sample locations, representing four lithofacies: clay- and organic-rich sands, organic-rich sands, clean quartz sands, and oyster bioherms. Samples were analyzed for texture, total organic matter, total carbon, total nitrogen, clay mineralogy, and major and trace-metal content. Following these analyses, metal concentrations were normalized against geochemical reference elements (aluminum and iron) and against total weight percent organic matter. Metals were also normalized granulometrically against total weight percent fines (<0.062 mm). Concentrations were determined by inductively coupled plasma-atomic emission spectrometry (ICP-AES) for all metals except mercury. Mercury concentrations were determined by cold-flameless atomic absorption spectrometry (AAS). Granulometric measurements were made by sieve and pipette analyses. Organic matter was determined by two methods: weight loss upon ignition and elemental analysis (by Carlo-Erba Furnace) of carbon and nitrogen. X

Health risk assessment of heavy metals in fish and accumulation patterns in food web in the upper Yangtze River, China.

PubMed

Yi, Yujun; Tang, Caihong; Yi, Tieci; Yang, Zhifeng; Zhang, Shanghong

2017-11-01

This study aims to concern the distribution of As, Cr, Cd, Hg, Cu, Zn, Pb and Fe in surface sediment, zoobenthos and fishes, and quantify the accumulative ecological risk and human health risk of metals in river ecological system based on the field investigation in the upper Yangtze River. The results revealed high ecological risk of As, Cd, Cu, Hg, Zn and Pb in sediment. As and Cd in fish presented potential human health risk of metals by assessing integrated target hazard quotient results based on average and maximum concentrations, respectively. No detrimental health effects of heavy metals on humans were found by daily fish consumption. While, the total target hazard quotient (1.659) exceeding 1, it meant that the exposed population might experience noncarcinogenic health risks from the accumulative effect of metals. Ecological network analysis model was established to identify the transfer routes and quantify accumulative effects of metals on river ecosystem. Control analysis between compartments showed large predator fish firstly depended on the omnivorous fish. Accumulative ecological risk of metals indicated that zoobenthos had the largest metal propagation risk and compartments located at higher trophic levels were not easier affected by the external environment pollution. A potential accumulative ecological risk of heavy metal in the food web was quantified, and the noncarcinogenic health risk of fish consumption was revealed for the upper reach of the Yangtze River. Copyright © 2017 Elsevier Inc. All rights reserved.

Dynamics of organic and inorganic carbon in surface sediments of the Yellow River Estuary

NASA Astrophysics Data System (ADS)

Yu, Z.; Wang, X.; Liu, X.; Zhang, E.; Hang, F.

2017-12-01

Estuarine sediment is an important carbon reservoir thus may play an important role in the global carbon cycle. However, little is known on the dynamics of organic carbon (OC) and inorganic carbon (IC) in the surface sediment of the Yellow River Estuary, a large estuary in northern China. In this study, we applied element analyses and isotopic approach to study spatial distribution and sources of OC and IC in the Yellow River Estuary. We found that TIC concentration (6.3-20.1 g kg-1) was much higher than TOC (0.2-4.4 g kg-1) in the surface sediment. There showed a large spatial variability in TOC and TIC and their stable isotopes. Both TOC and TIC were higher to the north (2.6 and 14.5 g kg-1) than to the south (1.6 and 12.2 g kg-1), except in the southern bay where TOC and TIC reached 2.7 and 15.4 g kg-1, respectively. Generally, TOC and TIC in our study area was mainly autochthonous. The lower TOC values in the south section were due to relatively higher kinetic energy level whereas the higher values in the bay was attributable to terrigenous matters accumulation and lower kinetic energy level. However, the southern bay revealed the most negative δ13Corg and δ13Ccarb, suggesting that there might exist some transfer of OC to IC in the section. Our study points out that the dynamics of sedimentary carbon in the Yellow River Estuary is influenced by multiple and complex processes, and highlights the importance of carbonate in carbon sequstration.

Migratory Behavior and Survival of Juvenile Salmonids in the Lower Columbia River, Estuary, and Plume in 2010

DOE Office of Scientific and Technical Information (OSTI.GOV)

McMichael, Geoffrey A.; Harnish, Ryan A.; Skalski, John R.

Uncertainty regarding the migratory behavior and survival of juvenile salmonids passing through the lower Columbia River and estuary after negotiating dams on the Federal Columbia River Power System (FCRPS) prompted the development and application of the Juvenile Salmon Acoustic Telemetry System (JSATS). The JSATS has been used to investigate the survival of juvenile salmonid smolts between Bonneville Dam (river kilometer (rkm) 236) and the mouth of the Columbia River annually since 2004. In 2010, a total of 12,214 juvenile salmonids were implanted with both a passive integrated transponder (PIT) and a JSATS acoustic transmitter. Using detection information from JSATS receivermore » arrays deployed on dams and in the river, estuary, and plume, the survival probability of yearling Chinook salmon and steelhead smolts tagged at John Day Dam was estimated form multiple reaches between rkm 153 and 8.3 during the spring. During summer, the survival probability of subyearling Chinook salmon was estimated for the same reaches. In addition, the influence of routes of passage (e.g., surface spill, deep spill, turbine, juvenile bypass system) through the lower three dams on the Columbia River (John Day, The Dalles, and Bonneville) on juvenile salmonid smolt survival probability from the dams to rkm 153 and then between rkm 153 and 8.3 was examined to increase understanding of the immediate and latent effects of dam passage on juvenile salmon survival. Similar to previous findings, survival probability was relatively high (>0.95) for most groups of juvenile salmonids from the Bonneville Dam tailrace to about rkm 50. Downstream of rkm 50 the survival probability of all species and run types we examined decreased markedly. Steelhead smolts suffered the highest mortality in this lower portion of the Columbia River estuary, with only an estimated 60% of the tagged fish surviving to the mouth of the river. In contrast, yearling and subyearling Chinook salmon smolts survived to

[Effects of Long-term Implementation of the Flow-Sediment Regulation Scheme on Grain and Clay Compositions of Inshore Sediments in the Yellow River Estuary].

PubMed

Wang, Miao-miao; Sun, Zhi-gao; Lu, Xiao-ning; Wang, Wei; Wang, Chuan-yuan

2015-04-01

Based on the laser particle size and X-ray diffraction (XRD) analysis, 28 sediment samples collected from the inshore region of the Yellow River estuary in October 2013 were determined to discuss the influence of long-term implementation of the flow-sediment regulation scheme (FSRS, initiated in 2002) on the distributions of grain size and clay components (smectite, illite, kaolinite and chlorite) in sediments. Results showed that, after the FSRS was implemented for more than 10 years, although the proportion of sand in inshore sediments of the Yellow River estuary was higher (average value, 23.5%) than those in sediments of the Bohai Sea and the Yellow River, silt was predominated (average value, 59.1%) and clay components were relatively low (average value, 17.4%). The clay components in sediments of the inshore region in the Yellow River estuary were close with those in the Yellow River. The situation was greatly changed due to the implementation of FSRS since 2002, and the clay components were in the order of illite > smectite > chlorite > kaolinite. This study also indicated that, compared to large-scale investigation in Bohai Sea, the local study on the inshore region of the Yellow River estuary was more favorable for revealing the effects of long-term implementation of the FSRS on sedimentation environment of the Yellow River estuary.

Massive production of heavy metals in the Ganga (Hooghly) River estuary, India: Global importance of solute-particle interaction and enhanced metal fluxes to the oceans

NASA Astrophysics Data System (ADS)

Samanta, Saumik; Dalai, Tarun K.

2018-05-01

The Ganga River System is a major contributor to the global sediment and water discharge to the oceans. The estuary of Ganga (Hooghly) River in India is under increasing influence of anthropogenic contributions via discharge of the industrial and urban effluents. Here we document, based on the investigation of water and suspended sediment samples collected during six periods over two years, that there is extensive production of heavy metals (Co, Ni and Cu) in the estuary such that the annual dissolved fluxes of metals from the Hooghly River are enhanced by up to 230-1770%. Furthermore, the estuarine dissolved metal fluxes, when normalized with water fluxes, are the highest among estuaries of the major rivers in the world. Our simultaneous data on the dissolved, suspended particulate and exchangeable phases allow us to identify the ion-exchange process (coupled adsorption and desorption) as the dominant contributor to the generation of heavy metals in the middle and lower estuary where the estimated anthropogenic contribution is negligible. The estimated contributions from the groundwater are also insufficient to explain the measured metal concentrations in the estuary. A strong positive correlation that is observed between the dissolved heavy metal fluxes and the suspended particulate matter (SPM) fluxes, after normalizing them with the water fluxes, for estuaries of the major global rivers imply that the solute-particle interaction is a globally significant process in the estuarine production of metals. Based on this correlation that is observed for major estuaries around the world, we demonstrate that the South Asian Rivers which supply only ∼9% of the global river water discharge but carry elevated SPM load, contribute a far more significant proportion (∼40 ± 2% Ni and 15 ± 1% Cu) to the global supply of the dissolved metals from the rivers.

Improving simulations of snow water equivalent and total water storage changes over the Upper Yangtze River basin using multi-source remote sensing data

NASA Astrophysics Data System (ADS)

Han, P.; Long, D.

2017-12-01

Snow water equivalent (SWE) and total water storage (TWS) changes are important hydrological state variables over cryospheric regions, such as China's Upper Yangtze River (UYR) basin. Accurate simulation of these two state variables plays a critical role in understanding hydrological processes over this region and, in turn, benefits water resource management, hydropower development, and ecological integrity over the lower reaches of the Yangtze River, one of the largest rivers globally. In this study, an improved CREST model coupled with a snow and glacier melting module was used to simulate SWE and TWS changes over the UYR, and to quantify contributions of snow and glacier meltwater to the total runoff. Forcing, calibration, and validation data are mainly from multi-source remote sensing observations, including satellite-based precipitation estimates, passive microwave remote sensing-based SWE, and GRACE-derived TWS changes, along with streamflow measurements at the Zhimenda gauging station. Results show that multi-source remote sensing information can be extremely valuable in model forcing, calibration, and validation over the poorly gauged region. The simulated SWE and TWS changes and the observed counterparts are highly consistent, showing NSE coefficients higher than 0.8. The results also show that the contributions of snow and glacier meltwater to the total runoff are 8% and 6%, respectively, during the period 2003‒2014, which is an important source of runoff. Moreover, from this study, the TWS is found to increase at a rate of 5 mm/a ( 0.72 Gt/a) for the period 2003‒2014. The snow melting module may overestimate SWE for high precipitation events and was improved in this study. Key words: CREST model; Remote Sensing; Melting model; Source Region of the Yangtze River

Current status of non-native fish species in the St. Louis River estuary

EPA Science Inventory

The fish community of the St. Louis River estuary is well characterized, thanks to fishery assessment and invasive species early detection monitoring by federal, state, and tribal agencies. This sampling includes long-standing adult/juvenile fish surveys, larval fish surveys beg...

River flow and ammonium discharge determine spring phytoplankton blooms in an urbanized estuary

NASA Astrophysics Data System (ADS)

Dugdale, Richard; Wilkerson, Frances; Parker, Alexander E.; Marchi, Al; Taberski, Karen

2012-12-01

Nutrient loadings to urbanized estuaries have increased over the past decades in response to population growth and upgrading to secondary sewage treatment. Evidence from the San Francisco Estuary (SFE) indicates that increased ammonium (NH4) loads have resulted in reduced primary production, a counter-intuitive finding; the NH4 paradox. Phytoplankton uptake of nitrate (NO3), the largest pool of dissolved inorganic nitrogen, is necessary for blooms to occur in SFE. The relatively small pool of ambient NH4, by itself insufficient to support a bloom, prevents access to NO3 and bloom development. This has contributed to the current rarity of spring phytoplankton blooms in the northern SFE (Suisun Bay), in spite of high inorganic nutrient concentrations, improved water transparency and seasonally low biomass of bivalve grazers. The lack of blooms has likely contributed to deleterious bottom-up impacts on estuarine fish. This bloom suppression may also occur in other estuaries that receive large amounts of anthropogenic NH4. In 2010 two rare diatom blooms were observed in spring in Suisun Bay (followed by increased abundances of copepods and pelagic fish), and like the prior bloom observed in 2000, chlorophyll accumulated after NH4 concentrations were decreased. In 2010, low NH4 concentrations were apparently due to a combination of reduced NH4 discharge from a wastewater treatment plant and increased river flow. To understand the interactions of river flow, NH4 discharge and bloom initiation, a conceptual model was constructed with three criteria; 1) NH4 loading must not exceed the capacity of the phytoplankton to assimilate the inflow of NH4, 2) the NH4 concentration must be ≤4 μmol L-1 to enable phytoplankton NO3 uptake, 3) the dilution rate of phytoplankton biomass set by river flow must not exceed the phytoplankton growth rate to avoid "washout". These criteria were determined for Suisun Bay; with sufficient irradiance and present day discharge of 15 tons NH4-N d

Uranium isotopes in rivers, estuaries and adjacent coastal sediments of western India: their weathering, transport and oceanic budget

NASA Astrophysics Data System (ADS)

Borole, D. V.; Krishnaswami, S.; Somayajulu, B. L. K.

1982-02-01

The two major river systems on the west coast of India, Narbada and Tapti, their estuaries and the coastal Arabian sea sediments have been extensively studied for their uranium concentrations and 238U /238U activity ratios. The 238U concentrations in the aqueous phase of these river systems exhibit a strong positive correlation with the sum of the major cations, σ Na + K + Mg + Ca, and with the HCO 3- ion contents. The abundance ratio of dissolved U to the sum of the major cations in these waters is similar to their ratio in typical crustal rocks. These findings lead us to conclude that 238U is brought into the aqueous phase along with major cations and bicarbonate. The strong positive correlation between 238U and total dissolved salts for selected rivers of the world yield an annual dissolved 238U flux of 0.88 × 10 10g/ yr to the oceans, a value very similar to its removal rate from the oceans, 1.05 × 10 10g/ yr, estimated based on its correlation with HCO 3- contents of rivers. In the estuaries, both 238U and its great-grand daughter 234U behave conservatively beyond chlorosities 0.14 g/l. These data confirm our earlier findings in other Indian estuaries. The behavior of uranium isotopes in the chlorosity zone 0.02-0.14 g/l, was studied in the Narbada estuary in some detail. The results, though not conclusive, seem to indicate a minor removal of these isotopes in this region. Reexamination of the results for the Gironde and Zaire estuaries (Martin et al., 1978a and b) also appear to confirm the conservative behavior of U isotopes in unpolluted estuaries. It is borne out from all the available data that estuaries beyond 0.14 g/l chlorosities act neither as a sink nor as a source for uranium isotopes, the behavior in the low chlorosity zones warrants further detailed investigation. A review of the uranium isotope measurements in river waters yield a discharge weighted-average 238U concentration of 0.22 μg/l with a 234U /238U activity ratio of 1.20 ± 0

Development of a preliminary relative risk model for evaluating regional ecological conditions in the Delaware River Estuary, USA.

PubMed

Iannuzzi, Timothy J; Durda, Judi L; Preziosi, Damian V; Ludwig, David F; Stahl, Ralph G; DeSantis, Amanda A; Hoke, Robert A

2010-01-01

Effective environmental management and restoration of urbanized systems such as the Delaware River Estuary requires a holistic understanding of the relative importance of various stressor-related impacts throughout the watershed, both historical and ongoing. To that end, it is important to involve as many stakeholders as possible in the management process and to develop a system for sharing of scientific data and information, as well as effective technical tools for evaluating and disseminating the data needed to make management decisions. In this study, we describe a preliminary assessment that was undertaken to evaluate the relative risks for the variety of stressors currently operating within the Delaware Estuary using a relative risk model (RRM) framework. This model was constructed using existing data and information on the ecological conditions and stressors in the main-stem Delaware River below the head of tide at Trenton, New Jersey, USA. A large database was developed with pertinent data from a variety of library, scientific, and regulatory sources. Data were compiled, reviewed, and characterized before development of the Estuary-specific RRM. Our primary goals and objectives in developing this preliminary RRM for the Estuary were to 1) determine if the RRM framework can be adapted to a large complex estuarine system such as the Delaware River, 2) identify the issues associated with adapting the model framework to the various management issues and regional areas/habitats of the River, 3) help identify data needs and potential refinements that might be needed to more specifically quantify relative stressor risks in various areas and habitats of the Estuary to better inform future management goals/actions by Stakeholders. The key conclusions of our preliminary assessment are 1) a diverse suite of stressors is likely affecting the ecological conditions of the Delaware Estuary, 2) chemical (toxicants/contaminants) and physical (sedimentation, habitat loss

Geochemistry of the Amazon Estuary

USGS Publications Warehouse

Smoak, Joseph M.; Krest, James M.; Swarzenski, Peter W

2006-01-01

The Amazon River supplies more freshwater to the ocean than any other river in the world. This enormous volume of freshwater forces the estuarine mixing out of the river channel and onto the continental shelf. On the continental shelf, the estuarine mixing occurs in a very dynamic environment unlike that of a typical estuary. The tides, the wind, and the boundary current that sweeps the continental shelf have a pronounced influence on the chemical and biological processes occurring within the estuary. The dynamic environment, along with the enormous supply of water, solutes and particles makes the Amazon estuary unique. This chapter describes the unique features of the Amazon estuary and how these features influence the processes occurring within the estuary. Examined are the supply and cycling of major and minor elements, and the use of naturally occurring radionuclides to trace processes including water movement, scavenging, sediment-water interaction, and sediment accumulation rates. The biogeochemical cycling of carbon, nitrogen, and phosphorus, and the significances of the Amazon estuary in the global mass balance of these elements are examined.

Association analysis between spatiotemporal variation of vegetation greenness and precipitation/temperature in the Yangtze River Basin (China).

PubMed

Cui, Lifang; Wang, Lunche; Singh, Ramesh P; Lai, Zhongping; Jiang, Liangliang; Yao, Rui

2018-05-23

The variation in vegetation greenness provides good understanding of the sustainable management and monitoring of land surface ecosystems. The present paper discusses the spatial-temporal changes in vegetation and controlling factors in the Yangtze River Basin (YRB) using Global Inventory Modeling and Mapping Studies (GIMMS) Normalized Difference Vegetation Index (NDVI) for the period 2001-2013. Theil-Sen Median trend analysis, Pearson correlation coefficients, and residual analysis have been used, which shows decreasing trend of the annual mean NDVI over the whole YRB. Spatially, the regions with significant decreasing trends were mainly located in parts of central YRB, and pronounced increasing trends were observed in parts of the eastern and western YRB. The mean NDVI during spring and summer seasons increased, while it decreased during autumn and winter seasons. The seasonal mean NDVI shows spatial heterogeneity due to the vegetation types. The correlation analysis shows a positive relation between NDVI and temperature over most of the YRB, whereas NDVI and precipitation show a negative correlation. The residual analysis shows an increase in NDVI in parts of eastern and western YRB and the decrease in NDVI in the small part of Yangtze River Delta (YRD) and the mid-western YRB due to human activities. In general, climate factors were the principal drivers of NDVI variation in YRB in recent years.

Effects of Human Activities on Submarine Topography in Lingding Bay of the Pearl River Estuary During the Last Decade

NASA Astrophysics Data System (ADS)

WU, Z. Y.; Saito, Y.; Milliman, J. D.; Zhao, D.; Zhou, J.

2015-12-01

Estuaries have been the site of intensive human activities. During the past century, decreased fluvial water and sediment discharge, increasing land reclamation, changing climate, and rising sea level have had an ever-increasing impact on river deltas, particularly those deltas bordering Southeast Asia. Using six stages of navigational and bathymetric chart data from 1906 to 2013 and 2 years (2012,2013) single-beam bathymetric data, together with more than 50 years of fluvial discharge data, we document the impact of human activities on the Pearl River Delta and its estuary at Lingding Bay. Between 1906 and 2010, land reclamation decreased the bay's water area by ~300 km2 (>17%), mostly at the expense of the shrinking intertidal and shallow subtidal mudflats. Before 1980, the estuary was mainly governed by natural processes with slight net deposition, whereas after 1980 dredging in the estuary and large port engineering projects changed the estuarine topography by shallowing the shoals and deepening the troughs. From 1955 to 2010, the water volume of Lingding Bay decreased by 536 × 106 m3 for a net decrease of 9.7 × 106 m3 a year, which indicates that approximately 9.7 Mt/yr of sediment was deposited in Lingding Bay during that period. In 2012 and 2013, large-scale human activities within Lingding Bay included continued dredging plus a surge of sand excavation that changed local water depths by ±5 m/yr, far exceeding the range of natural topographic evolution in the estuary. The impacts of various human activities have significantly changed submarine topography in Lingding Bay of the complex Pearl River Estuary. With continuing economic expansion in the Pearl River Delta, Lingding Bay should continue to shrink in both area and water volume.

Sedimentary fabrics of the macrotidal, mud-dominated, inner estuary to fluvio-tidal transition zone, Petitcodiac River estuary, New Brunswick, Canada

NASA Astrophysics Data System (ADS)

Shchepetkina, Alina; Gingras, Murray K.; Zonneveld, John-Paul; Pemberton, S. George

2016-03-01

The study provides a detailed description of mud-dominated sedimentary fabrics and their application for the rock record within the inner estuary to the fluvial zone of the Petitcodiac River estuary, New Brunswick, Canada. Sedimentological characteristics and facies distributions of the clay- and silt-rich deposits are reported. The inner estuary is characterized by thick accumulations of interbedded silt and silty clay on intertidal banks that flank the tidally influenced channel. The most common sedimentary structures observed are parallel and wavy lamination, small-scale soft-sediment deformation with microfaults, and clay and silt current ripples. The tidal channel contains sandy silt and clayey silt with planar lamination, massive and convolute bedding. The fluvio-tidal transition zone is represented by interbedded trough cross-stratified sand and gravel beds with planar laminated to massive silty mud. The riverine, non-tidal reach of the estuary is characterized by massive, planar tabular and trough cross-stratified gravel-bed deposits. The absence of bioturbation within the inner estuary to the fluvio-tidal transition zone can be explained by the following factors: low water salinities (0-5 ppt), amplified tide and current speeds, and high concentrations of flocculated material in the water body. Notably, downstream in the middle and outer estuary, bioturbation is seasonally pervasive: in those locales the sedimentary conditions are similar, but salinity is higher. In this study, the sedimentological (i.e., grain size, bedding characters, sedimentary structures) differences between the tidal estuary and the fluvial setting are substantial, and those changes occur over only a few hundred meters. This suggests that the widely used concept of an extensive fluvio-tidal transition zone and its depositional character may not be a geographically significant component of fluvial or estuary deposits, which can go unnoticed in the study of the ancient rocks.

Preventing and controlling land subsidence in Shanghai -towards more integrated and effective land use and ground water governance in the Yangtze Delta

NASA Astrophysics Data System (ADS)

Dai, Liping

2016-04-01

The Yangtze Delta, covers 210,700 square kilometers and with 156 million inhabitants (NRDC, 2010; The National Bureau of Statistics, 2011), is one of the areas most severely affected by land subsidence in China. Up to 2012, the area with cumulative subsidence above 200 mm in Yangtze Delta has been closed to 10,000 square kilometers. Shanghai, located at the estuary of the Yangtze River and with a population of 23 million, is the most densely populated city in Yangtze Delta (The National Bureau of Statistics, 2011). Since 1921, the recorded cumulative subsidence has been 200 to 300 mm in the central area of the city (Chai, Shen, Zhu, & Zhang, 2005). Excessive pumping of groundwater is considered to be the leading reason, accounts for nearly 70%, of the city's land subsidence, the weight of skyscrapers and global warming also play hefty roles (30%) (Springer, 2012). Research has shown that the main method to control land subsidence in Shanghai is to prevent groundwater from dropping (Chai, Shen, Zhu, & Zhang, 2005), the city has made great efforts in this regard since 1965 (the beginning of the so-called "control period"), for example, it has been recharging underground water through 121 wells with more than 60,000 tons every day since 2012 (Chinadaily, 2012). It is a huge burden considering the city has been suffering from a shortage of fresh water. In 2013, with the other two provinces of Jiangsu and Zhejiang in Yangtze Delta, Shanghai signed a delta cooperation agreement on the prevention and control of land subsidence and jointly issued a Prevention and Control Planning on Land Subsidence in Yangtze Delta (2014-2020), which aims to establish a long-effect mechanism in the delta scope. This research aims to analyze and assess the land and groundwater governance arrangements related to land subsidence in the Yangtze Delta in general and Shanghai in specific, in order to develop optimizing adaptation strategies and associated governance arrangements. It examines the

Evaluation of Cumulative Ecosystem Response to Restoration Projects in the Lower Columbia River and Estuary, 2010

DOE Office of Scientific and Technical Information (OSTI.GOV)

Johnson, Gary E.; Diefenderfer, Heida L.; Thom, Ronald M.

This is the seventh and final annual report of a project (2004–2010) addressing evaluation of the cumulative effects of habitat restoration actions in the 235-km-long lower Columbia River and estuary. The project, called the Cumulative Effects (CE) study, was conducted for the U.S. Army Corps of Engineers Portland District by a collaboration of research agencies led by the Pacific Northwest National Laboratory. We achieved the primary goal of the CE study to develop a methodology to evaluate the cumulative effects of habitat actions in the Columbia Estuary Ecosystem Restoration Program. We delivered 1) standard monitoring protocols and methods to prioritizemore » monitoring activities; 2) the theoretical and empirical basis for a CE methodology using levels-of-evidence; 3) evaluations of cumulative effects using ecological relationships, geo-referenced data, hydrodynamic modeling, and meta-analyses; and 4) an adaptive management process to coordinate and coalesce restoration efforts in the LCRE. A solid foundation has been laid for future comprehensive evaluations of progress made by the Columbia Estuary Ecosystem Restoration Program to understand, conserve, and restore ecosystems in the lower Columbia River and estuary.« less

A Numerical Modeling Study of Mesodinium Bloom Formation and Retention in a River-Dominated Mesotidal Estuary

NASA Astrophysics Data System (ADS)

Spitz, Y. H.; Cervantes, B.

2016-02-01

The Columbia River estuary experiences extensive seasonal red-colored blooms caused by a mixotrophic ciliate of the genus Mesodinium. Although the blooms are non-toxic, they have a significant influence on the levels of nutrients, light and oxygen in the estuary. Mesodinium spp. displays very particular physiology that makes it one of few planktonic species able to thrive in a highly flushed system: a high growth rate due to its ability to photosynthesize using the photosynthetic organelles of its preys, and complex vertical migration patterns. Knowledge of the migration pattern is based on limited observations of Mesodinium behavior in culture and recent in-situ measurements collected in the Columbia River estuary. A more comprehensive understanding is needed of the mechanisms allowing Mesodinium spp. to be retained and experience rapid growth. To this end, we extended the finite element circulation model SELFE to include a 5-component behavioral model that simulates the relationships between nutrients, detritus, Mesodinium spp. and its cryptophyte prey. We then used the model to investigate various migration patterns and growth scenarios to determine their role in the formation and retention of the Mesodinium spp. bloom in the brackish water of the estuary.

Investigating phenology of larval fishes in St. Louis River estuary shallow water habitats

EPA Science Inventory

As part of the development of an early detection monitoring strategy for non-native fishes, larval fish surveys have been conducted since 2012 in the St. Louis River estuary. Survey data demonstrates there is considerable variability in fish abundance and species assemblages acro...

Comparison among the microbial communities in the lake, lake wetland, and estuary sediments of a plain river network.

PubMed

Huang, Wei; Chen, Xing; Wang, Kun; Chen, Junyi; Zheng, Binghui; Jiang, Xia

2018-06-10

Sediment microbial communities from plain river networks exert different effects on pollutant transformation and migration in lake basins. In this study, we examined millions of Illumina reads (16S rRNA gene amplicons) to compare lake, lake wetland, and estuary bacterial communities through a technically consistent approach. Results showed that bacterial communities in the sampled lake sediments had the highest alpha-diversity (Group B), than in sampled lake wetland sediments and estuary sediments. Proteobacteria was the most abundant (more than 30%) phyla in all the sediments. The lake sediments had more Nitrospirae (1.63%-11.75%) and Acidobacteria (3.46%-10.21%) than the lake wetland and estuary sediments, and estuary sediments had a greater abundance of the phylum Firmicutes (mean of 22.30%). Statistical analysis (LEfSe) revealed that lake wetland sediments contained greater abundances of the class Anaerolineaceae, orders Xanthomonadales, Pseudomonadales, and genera Flavobacterium, Acinetobacter. The lake sediments had a distinct community of diverse primary producers, such as phylum Acidobacteria, order Ignavibacteriales, and families Nitrospiraceae, Hydrogenophilaceae. Total phosphorus and organic matter were the main factors influencing the bacterial communities in sediments from several parts of the lake wetland and river estuary (p < .05). The novel insights into basin pollution control in plain river networks may be obtained from microbial distribution in sediments from different basin regions. © 2018 The Authors. MicrobiologyOpen published by John Wiley & Sons Ltd.

Tidal currents and bedload transport at the mouth of a rock-bound estuary during low river discharge conditions (Guadiana Estuary, Portugal)

NASA Astrophysics Data System (ADS)

Garel, E.; Pacheco, A.; Ferreira, Ó.

2009-04-01

The present study documents the poorly-described hydro-sediment dynamics of narrow bedrock-controlled estuaries during periods of low-river discharge. The results also contribute to assess the geomorphological evolution of these systems, when affected by drastic flow regulation. The Guadiana Estuary is a narrow rock-bound mesotidal estuary, 80 km in length, located at the southern border between Spain and Portugal. Until recently, the river inputs to the estuary displayed high (annual and seasonal) variability, characterized by periods of droughts, and episodic flood events with (monthly-averaged) fluvial discharge as high as 5,000 m3s-1 (160 m3s-1 in average, for the period 1947/2001). This pattern has ceased in February 2002, with the impoundment of the main river by the large Alqueva dam, 60 km upstream from the estuary head. At present, the daily-averaged river discharge is generally kept low throughout the year (< 50 m3s-1). In the absence of significant flood events to expel massively sediment out of the estuary, concerns have been raised about sand infilling at the mouth and increased erosion at the adjacent coastline. For the assessment of the sediment balance of the estuary under present hydrodynamic conditions, this study examines the tidal currents and bedload transport at the entrance of the estuarine channel. Current measurement transects were performed across the 600 m-wide channel entrance using a ship borne Acoustic Doppler Profiler (ADP, operating at 1.5 MHz frequency) during 2 entire tidal cycles, at spring (17 September 2008, 3.0 m tidal range) and at neap tide (21 October 2008, 1.6 m tidal range). Surficial sediment samples were also collected across the channel during the spring tidal cycle. The bed sediment consists of well-sorted medium sand with mean grain size ranging from 0.5 to 0.3 mm (with coarser material at the deepest part of the channel cross-section). Tidal currents were analysed along 6 sub-sections to take into account these grain

Seasonal variation in drifting eggs and larvae in the upper Yangtze, China.

PubMed

Jiang, Wei; Liu, Huan-Zhang; Duan, Zhong-Hua; Cao, Wen-Xuan

2010-05-01

From 5 March to 25 July 2008, ichthyoplankton drifting into the Three Gorges Reservoir from the upper reaches of the Yangtze River were sampled daily to investigate the species composition, abundance, and seasonal variation in early-stage fishes in this area. Twenty-eight species belonging to five orders and 17 families or subfamilies were identified by analyzing fish eggs and larvae, and a total of 14.16 billion individuals were estimated drifting through the sampling section during the investigation. Among the ichthyoplankton sampled, species in Cultrinae, Cobitidae, Gobioninae and Gobiidae, along with the common carp (Cyprinus carpio Linnaeus), comprised 89.6% of the total amount. Six peaks of drift density were identified during the sampling period, and a significant correlation was found between drift density with water discharge. The dominant species were different in each drift peak, indicating different spawning times for the major species. The total amount of the four major Chinese carps that drifted through the sampling section was estimated as 0.88 billion, indicating an increase in the population sizes of these species in the upper reaches of the Yangtze River after construction of the Three Gorges Dam. Actually, these reaches have become the largest spawning area for the four major Chinese carps in the Yangtze River. The large total amount of eggs and larvae drifting through this section demonstrated that the upper reaches of the Yangtze River provided important spawning sites for many fish species, and that conservation of this area should be of great concern.

Hydro-sedimentary processes of a shallow tropical estuary under Amazon influence. The Mahury Estuary, French Guiana

NASA Astrophysics Data System (ADS)

Orseau, Sylvain; Lesourd, Sandric; Huybrechts, Nicolas; Gardel, Antoine

2017-04-01

Along the Guianas coast, coastal dynamic is characterized by the migration of mud banks originating from the Amazon. This singular feature affects the dynamic and the morphology of local estuaries and can induce rapid bathymetric evolution in lower estuaries. Since 2012, the navigation channel of the Mahury Estuary (French Guiana) is enduring a severe siltation whose origin comes from a mud bank crossing the estuary mouth. This study aims to determine how the migration of a mud bank through an estuary mouth could influence the transport and fluxes in the estuary. Field measurements were performed over a year with the monitoring of the salt intrusion length, mooring surveys during spring-neap cycles and shipboard profiling surveys during semi-diurnal cycles. Salt intrusion lengths underline a significant seasonal variation characterized by the transition from a steady-state length during high river discharge and a wide range of lengths with the tidal range during low to moderate river discharge. During the rainy season, measurements indicate a fluvial-dominated condition with low suspended-sediment concentrations most of the semi-diurnal cycle. Residual sediment fluxes are usually seaward excepted when river discharge is below seasonal average. During the dry season, maximum suspended-sediment concentrations are higher in the middle part of the estuary. Residual sediment fluxes are landward along the estuary and stronger during neap tides in the estuary mouth and few kilometers upstream. In this area, a persistent density stratification traps sediments in the bottom layer and generates a gravitational circulation during neap tides, which enhances landward transports up to 2.56 t m-1 over a semi-diurnal cycle. In the middle estuary, landward fluxes are most significant during the dry season and also during the rainy season when the river discharge is below the seasonal average. Although this study includes temporal and spatial limitations, it underlines significant

[Effect of water conservancy schistosomiasis control projects combined with molluscicide to control Oncomelania hupensis snails in rivers connecting with Yangtze River in Pukou District, Nanjing City].

PubMed

Qiang, Zhou; Li-Xin, Wan; De-Rong, Hang; Qi-Hui, You; Jun, You; Yu-Lin, Zhang; Zhao-Feng, Zhu; Yi-Xin, Huang

2017-12-07

To evaluate the effect of the water conservancy schistosomiasis control projects combined with molluscicide to control Oncomelania hupensis snails in the rivers connecting with the Yangtze River. The water conservancy schistosomiasis control projects of Zhujiashan River, Qili River and Gaowang River were chosen as the study objects in Pukou District, Nanjing City. The data review method and field investigation were used to evaluate the effect of the water conservancy schistosomiasis control projects combined with molluscicide to control O. hupensis snails. After the projects of the water level control and concrete slope protection and mollusciciding were implemented, the snails in the project river sections were completely eliminated. The snail diffusion did not happen in the inland irrigation area too. In the outside of the river beach, though the snails still existed, the snail densities plunged below 1.0 snail per 1.0 m 2 . The comprehensive measures of the combination of water level control, concrete slope protection and mollusciciding can effectively control and eliminate the snails, and prevent the snails from spreading.

Microplastics in oysters Saccostrea cucullata along the Pearl River Estuary, China.

PubMed

Li, Heng-Xiang; Ma, Li-Sha; Lin, Lang; Ni, Zhi-Xin; Xu, Xiang-Rong; Shi, Hua-Hong; Yan, Yan; Zheng, Guang-Ming; Rittschof, Daniel

2018-05-01

As a transitional zone between riverine and marine environments, an estuary plays an important role for the sources, accumulation and transport of microplastics. Although estuarine environments are hotspots of microplastic pollution, the correlation between microplastic pollution and aquatic organisms is less known. Here we investigated microplastic pollution in wild oysters Saccostrea cucullata from 11 sampling sites along the Pearl River Estuary in South China. The microplastic abundances in oysters ranged from 1.4 to 7.0 items per individual or from 1.5 to 7.2 items per gram tissue wet weight, which were positively related to those in surrounding waters. The oysters near urban areas contained significantly more microplastics than those near rural areas. Fibers accounted for 69.4% of the total microplastics in oysters. Microplastic sizes varied from 20 to 5000 μm and 83.9% of which were less than 100 μm. Light color microplastics were significantly more common than dark color ones. Based on the results, oysters are recommended as a biomonitor for the microplastic pollution in estuaries. Copyright © 2018 Elsevier Ltd. All rights reserved.

Contribution of wave-induced liquefaction in triggering hyperpycnal flows in Yellow River Estuary

NASA Astrophysics Data System (ADS)

Liu, X.; Jia, Y.

2017-12-01

Hyperpycnal flows, driven mainly by the gravity of near-bed negatively buoyant layers, are one of the most important processes for moving marine sediment across the earth. The issue of hyperpycnal flows existing in marine environment has drawn increasing scholars' attention since that was observed in situ off the Yellow River estuary in the 1980s. Most researches maintain that hyperpycnal flows in the Yellow River estuary are caused by the high-concentration sediments discharged from the Yellow River into sea, however, other mechanisms have been discounted since the sediment input from the river has been significantly changed due to climate and anthropogenic change. Here we demonstrate that wave-seabed interactions can generate hyperpycnal flows, without river input, by sediment flux convergence above an originally consolidated seabed. Using physical model experiments and multi-sensor field measurements, we characterize the composition-dependent liquefaction properties of the sediment due to wave-induced pore water pressure accumulation. This allows quantification of attenuation of sediment threshold velocity and critical shear stress (predominant variables in transport mechanics) during the liquefaction under waves. Parameterising the wave-seabed interactions in a new concept model shows that high waves propagating over the seabed sediment can act as a scarifier plough remoulding the seabed sediment. This contributes to marine hyperpycnal flows as the sediment is quickly resuspended under accumulating attenuation in strength. Therefore, the development of more integrative numerical models could supply realistic predictions of marine record in response to rising magnitude and frequency of storms.

Distributions and Relationships of CO2, O2, and Dimethylsulfide in the Changjiang (Yangtze) Estuary and Its Adjacent Waters in Summer

NASA Astrophysics Data System (ADS)

Wu, Xi; Tan, Tingting; Liu, Chunying; Li, Tie; Liu, Xiaoshou; Yang, Guipeng

2018-04-01

The distributions and relationships of O2, CO2, and dimethylsulfide (DMS) in the Changjiang (Yangtze) Estuary and its adjacent waters were investigated in June 2014. In surface water, mean O2 saturation level, partial pressure of CO2 (pCO2), and DMS concentrations (and ranges) were 110% (89%-167%), 374 μatm (91-640 μatm), and 8.53 nmol L-1 (1.10-27.50 nmol L-1), respectively. The sea-to-air fluxes (and ranges) of DMS and CO2 were 8.24 μmol m-2 d-1 (0.26-62.77 μmol m-2 d-1), and -4.7 mmol m-2 d-1 (-110.8-31.7 mmol m-2 d-1), respectively. Dissolved O2 was oversaturated, DMS concentrations were relatively high, and this region served as a sink of atmospheric CO2. The pCO2 was significantly and negatively correlated with the O2 saturation level, while the DMS concentration showed different positive relationships with the O2 saturation level in different water masses. In vertical profiles, a hypoxic zone existed below 20 m at a longitude of 123°E. The stratification of temperature and salinity caused by the Taiwan Warm Current suppressed seawater exchange between upper and lower layers, resulting in the formation of a hypoxic zone. Oxidative decomposition of organic detritus carried by the Changjiang River Diluted Water (CRDW) consumed abundant O2 and produced additional CO2. The DMS concentrations decreased because of low phytoplankton biomass in the hypoxic zone. Strong correlations appeared between the O2 saturation level, pCO2 and DMS concentrations in vertical profiles. Our results strongly suggested that CRDW played an important role in the distributions and relationships of O2, CO2, and DMS.

CO2 emissions from a temperate drowned river valley estuary adjacent to an emerging megacity (Sydney Harbour)

NASA Astrophysics Data System (ADS)

Tanner, E. L.; Mulhearn, P. J.; Eyre, B. D.

2017-06-01

The Sydney Harbour Estuary is a large drowned river valley adjacent to Sydney, a large urban metropolis on track to become a megacity; estimated to reach a population of 10 million by 2100. Monthly underway surveys of surface water pCO2 were undertaken along the main channel and tributaries, from January to December 2013. pCO2 showed substantial spatio-temporal variability in the narrow high residence time upper and mid sections of the estuary, with values reaching a maximum of 5650 μatm in the upper reaches and as low as 173 μatm in the mid estuary section, dominated by respiration and photosynthesis respectively. The large lower estuary displayed less variability in pCO2 with values ranging from 343 to 544 μatm controlled mainly by tidal pumping and temperature. Air-water CO2 emissions reached a maximum of 181 mmol C m-2 d-1 during spring in the eutrophic upper estuary. After a summer high rainfall event nutrient-stimulated biological pumping promoted a large uptake of CO2 transitioning the Sydney Harbour Estuary into a CO2 sink with a maximum uptake of rate of -10.6 mmol C m-2 d-1 in the mid-section of the estuary. Annually the Sydney Harbour Estuary was heterotrophic and a weak source of CO2 with an air-water emission rate of 1.2-5 mmol C m-2 d-1 (0.4-1.8 mol C m-2 y-1) resulting in a total carbon emission of around 930 tonnes per annum. CO2 emissions (weighted m3 s-1 of discharge per km2 of estuary surface area) from Sydney Harbour were an order of magnitude lower than other temperate large tectonic deltas, lagoons and engineered systems of China, India, Taiwan and Europe but were similar to other natural drowned river valley systems in the USA. Discharge per unit area appears to be a good predictor of CO2 emissions from estuaries of a similar climate and geomorphic class.

Effect of winds and waves on salt intrusion in the Pearl River estuary

NASA Astrophysics Data System (ADS)

Gong, Wenping; Lin, Zhongyuan; Chen, Yunzhen; Chen, Zhaoyun; Zhang, Heng

2018-02-01

Salt intrusion in the Pearl River estuary (PRE) is a dynamic process that is influenced by a range of factors and to date, few studies have examined the effects of winds and waves on salt intrusion in the PRE. We investigate these effects using the Coupled Ocean-Atmosphere-Wave-Sediment Transport (COAWST) modeling system applied to the PRE. After careful validation, the model is used for a series of diagnostic simulations. It is revealed that the local wind considerably strengthens the salt intrusion by lowering the water level in the eastern part of the estuary and increasing the bottom landward flow. The remote wind increases the water mixing on the continental shelf, elevates the water level on the shelf and in the PRE and pumps saltier shelf water into the estuary by Ekman transport. Enhancement of the salt intrusion is comparable between the remote and local winds. Waves decrease the salt intrusion by increasing the water mixing. Sensitivity analysis shows that the axial down-estuary wind, is most efficient in driving increases in salt intrusion via wind straining effect.

River flow, zooplankton and dominant zooplanktivorous fish dynamics in a warm-temperate South African estuary.

PubMed

Mbandzi, N; Wasserman, R J; Deyzel, S H P; Vine, N G; Whitfield, A K

2018-06-01

The possible links between river flow, zooplankton abundance and the responses of zooplanktivorous fishes to physico-chemical and food resource changes are assessed. To this end, the seasonal abundance, distribution and diet of the estuarine round-herring Gilchristella aestuaria and Cape silverside Atherina breviceps were studied in the Kariega Estuary. Spatio-temporal differences were determined for selected physico-chemical variables, zooplankton abundance and zooplanktivorous fish abundance and distribution. Results indicated that, following a river flood event in winter (>30 m 3  s -1 ), altered physico-chemical conditions occurred throughout the estuary and depressed zooplankton stocks. Abundance of G. aestuaria was highest in spring, with this species dominant in the upper and middle zones of the estuary, while A. breviceps was dominant in summer and preferred the middle and lower zones. The catch per unit of effort of both zooplanktivores also declined significantly following the flooding, thus suggesting that these fishes are reliant on zooplankton as a primary food source for healthy populations. Copepods dominated the stomach contents of both fish species, indicating a potential for strong interspecific competition for food, particularly in the middle reaches. Temporal differences were evident in dietary overlap between the two zooplanktivorous fish species and were correlated with river flow, zooplankton availability and fish distribution. The findings of this study emphasize the close trophic linkages between zooplankton and zooplanktivorous fishes under changing estuarine environmental conditions, particularly river flow and provide important baseline information for similar studies elsewhere in South Africa and the rest of the world. © 2018 The Fisheries Society of the British Isles.

Carbonate system and nutrients in the Pearl River estuary, China: Seasonal and inter-annual variations

NASA Astrophysics Data System (ADS)

Guo, X.

2017-12-01

Located in southern China and surrounded by several metropolis, the Pearl River estuary is a large subtropical estuary under significant human perturbation. We examined the impact of sewage treatment rate on the water environmental factors. Carbonate system parameters (Dissolved inorganic carbon or DIC, Total alkalinity or TA, and pH), and nutrients were surveyed in the Pearl River estuary from 2000 to 2015. Spatially, concentrations of nutrients were high at low salinity and decreased with salinity in both wet and dry seasons although seasonal variation occurred. However, distribution patterns of DIC and TA differed in wet and dry seasons. In wet season, both DIC and TA were low at low salinity (600-1500 umol kg-1) and increased with salinity, but in dry season they were high at low salinity (3000-3500 umol kg-1) and decreased with salinity. Compared with the years before 2010, both values and distribution patterns of DIC, TA and pH were similar among the years in wet season, but they were conspicuously different in the upper estuary in dry season. Both DIC and TA were more than 1000 umol kg-1 lower than those in the years before 2010. For nutrients at low salinity, the ammonia concentration was much lower in the years after 2010 (200 vs. 400 umol kg-1 in wet season and 400 vs. 800 umol kg-1 in dry season), but nitrate concentration was slightly higher (180 vs 120 mmol kg-1 in wet season and 200 vs 180 mmol kg-1 in dry season). As a reference, carbonate system parameters and nutrients were stable among the 16 years in the adjacent northern South China Sea. The variations in biogeochemical processes induced by nutrients concentration and structure as a result of sewage discharge will be discussed in detail. The decrease in DIC, TA and nutrients in the upper Pearl River estuary after 2010 was due mainly to the improvement of sewage treatment rate and capacity.

Analysis of change of red tide species in Yodo River estuary by the numerical ecosystem model.

PubMed

Hayashi, Mitsuru; Yanagi, Tetsuo

2008-01-01

Occurrence number of red tides in Osaka Bay in Japan is more than 20 cases every year. Diatom red tide was dominant in Osaka Bay, but the non-diatom red tide was dominant in early 1990s. Therefore, the material cycling in Yodo River estuary in Osaka Bay during August from 1991 to 2000 was analyzed by using the numerical ecosystem model and field observation data to clarify the reasons of change in red tide species. Year-to-year variation in calculated concentration ratio of diatom to non-diatom corresponds to the variation in observed ratio of red tide days of diatom to non-diatom. Limiting nutrient of primary production is phosphate over the period. Diatom dominated from 1991 to 1993, but it was difficult for non-diatom to grow due to the limitation by physical condition. Non-diatom was able to grow because of good physical and nutrient conditions from 1994 to 1996. And diatom dominated again under the good physical condition, and phosphorus supply was not enough for non-diatom to grow from 1998 to 2000. Phosphate concentration in the lower layer of Yodo River estuary was important to the variation in red tide species in the upper layer of Yodo River estuary.

Mercury bioaccumulation in aquatic biota along a salinity gradient in the Saint John River estuary.

PubMed

Reinhart, Bethany L; Kidd, Karen A; Curry, R Allen; O'Driscoll, Nelson J; Pavey, Scott A

2018-06-01

Although estuaries are critical habitats for many aquatic species, the spatial trends of toxic methylmercury (MeHg) in biota from fresh to marine waters are poorly understood. Our objective was to determine if MeHg concentrations in biota changed along a salinity gradient in an estuary. Fourspine Stickleback (Apeltes quadracus), invertebrates (snails, amphipods, and chironomids), sediments, and water were collected from ten sites along the Saint John River estuary, New Brunswick, Canada in 2015 and 2016, with salinities ranging from 0.06 to 6.96. Total mercury (proxy for MeHg) was measured in whole fish and MeHg was measured in a subset of fish, pooled invertebrates, sediments, and water. Stable sulfur (δ 34 S), carbon (δ 13 C), and nitrogen (δ 15 N) isotope values were measured to assess energy sources (S, C) and relative trophic level (N). There were increases in biotic δ 13 C and δ 34 S from fresh to more saline sites and these measures were correlated with salinity. Though aqueous MeHg was higher at the freshwater than more saline sites, only chironomid MeHg increased significantly with salinity. In the Saint John River estuary, there was little evidence that MeHg and its associated risks increased along a salinity gradient. Copyright © 2018. Published by Elsevier B.V.

The Partitioning of Triclosan between Aqueous and Particulate Phases in the Hudson River Estuary

EPA Science Inventory

The distribution of Triclosan within the Hudson River Estuary can be explained by a balance among the overall effluent inputs from municipal sewage treatment facilities, dilution of Triclosan concentrations in the water column with freshwater and seawater inputs, removal of Tricl...

Discharge-measurement system using an acoustic Doppler current profiler with applications to large rivers and estuaries

USGS Publications Warehouse

Simpson, Michael R.; Oltmann, Richard N.

1993-01-01

Discharge measurement of large rivers and estuaries is difficult, time consuming, and sometimes dangerous. Frequently, discharge measurements cannot be made in tide-affected rivers and estuaries using conventional discharge-measurement techniques because of dynamic discharge conditions. The acoustic Doppler discharge-measurement system (ADDMS) was developed by the U.S. Geological Survey using a vessel-mounted acoustic Doppler current profiler coupled with specialized computer software to measure horizontal water velocity at 1-meter vertical intervals in the water column. The system computes discharge from water-and vessel-velocity data supplied by the ADDMS using vector-algebra algorithms included in the discharge-measurement software. With this system, a discharge measurement can be obtained by engaging the computer software and traversing a river or estuary from bank to bank; discharge in parts of the river or estuarine cross sections that cannot be measured because of ADDMS depth limitations are estimated by the system. Comparisons of ADDMS-measured discharges with ultrasonic-velocity-meter-measured discharges, along with error-analysis data, have confirmed that discharges provided by the ADDMS are at least as accurate as those produced using conventional methods. In addition, the advantage of a much shorter measurement time (2 minutes using the ADDMS compared with 1 hour or longer using conventional methods) has enabled use of the ADDMS for several applications where conventional discharge methods could not have been used with the required accuracy because of dynamic discharge conditions.

Quantitative assessment of benthic food resources for juvenile Gulf sturgeon, Acipenser oxyrinchus desotoi in the Suwannee River estuary, Florida, USA

USGS Publications Warehouse

Brooks, R.A.; Sulak, K.J.

2005-01-01

Gulf sturgeon, Acipenser oxyrinchus desotoi, forage extensively in the Suwannee River estuary following emigration out of the Suwannee River, Florida. While in the estuary, juvenile Gulf sturgeon primarily feed on benthic infauna. In June-July 2002 and February-April 2003, random sites within the estuary were sampled for benthic macrofauna (2002 n = 156; 2003 n = 103). A mean abundance of 2,562 ind m-2 (SE ?? 204) was found in the summer, with significantly reduced macrofaunal abundance in the winter (mean density of 1,044 ind m-2, SE ?? 117). Benthic biomass was significantly higher in the summer with an average summer sample dry weight of 5.92 g m-2 (SE ?? 0.82) compared to 3.91 g m-2 (SE ?? 0.67) in the winter. Amphipods and polychaetes were the dominant taxa collected during both sampling periods. Three different estimates of food availability were examined taking into account principal food item information and biomass estimates. All three estimates provided a slightly different view of potential resources but were consistent in indicating that food resource values for juvenile Gulf sturgeon are spatially heterogeneous within the Suwannee River estuary. ?? 2005 Estuarine Research Federation.

Influence of multiple dam passage on survival of juvenile Chinook salmon in the Columbia River estuary and coastal ocean

PubMed Central

Rechisky, Erin L.; Welch, David W.; Porter, Aswea D.; Jacobs-Scott, Melinda C.; Winchell, Paul M.

2013-01-01

Multiple dam passage during seaward migration is thought to reduce the subsequent survival of Snake River Chinook salmon. This hypothesis developed because juvenile Chinook salmon from the Snake River, the Columbia River’s largest tributary, migrate >700 km through eight hydropower dams and have lower adult return rates than downstream populations that migrate through only 3 or 4 dams. Using a large-scale telemetry array, we tested whether survival of hatchery-reared juvenile Snake River spring Chinook salmon is reduced in the estuary and coastal ocean relative to a downstream, hatchery-reared population from the Yakima River. During the initial 750-km, 1-mo-long migration through the estuary and coastal ocean, we found no evidence of differential survival; therefore, poorer adult returns of Snake River Chinook may develop far from the Columbia River. Thus, hydrosystem mitigation efforts may be ineffective if differential mortality rates develop in the North Pacific Ocean for reasons unrelated to dam passage. PMID:23576733

Biological thresholds of nitrogen and phosphorus in a typical urban river system of the Yangtz delta, China.

PubMed

Liang, Xinqiang; Zhu, Sirui; Ye, Rongzhong; Guo, Ru; Zhu, Chunyan; Fu, Chaodong; Tian, Guangming; Chen, Yingxu

2014-09-01

River health and associated risks are fundamentally dependent on the levels of the primary productivities, i.e., sestonic and benthic chlorophyll-a. We selected a typical urban river system of the Yangtz delta to investigate nutrient and non-nutrient responses of chlorophyll-a contents and to determine biological thresholds of N and P. Results showed the mean contents of sestonic and benthic chlorophyll-a across all sampling points reached 10.2 μg L(-1) and 149.3 mg m(-2). The self-organized mapping analysis suggested both chlorophyll-a contents clearly responded to measurements of N, P, and water temperature. Based on the chlorophyll-a criteria for fresh water and measured variables, we recommend the biological thresholds of N and P for our river system be set at 2.4 mg N L(-1) and 0.2 mg P L(-1), and these be used as initial nutrient reference values for local river managers to implement appropriate strategies to alleviate nutrient loads and trophic status. Copyright © 2014 Elsevier Ltd. All rights reserved.

Use of glacier river-fed estuary channels by juvenile coho salmon: transitional or rearing habitats?

USGS Publications Warehouse

Hoem Neher, Tammy D.; Rosenberger, Amanda E.; Zimmerman, Christian E.; Walker, Coowe M.; Baird, Steven J.

2014-01-01

Estuaries are among the most productive ecosystems in the world and provide important rearing environments for a variety of fish species. Though generally considered important transitional habitats for smolting salmon, little is known about the role that estuaries serve for rearing and the environmental conditions important for salmon. We illustrate how juvenile coho salmonOncorhynchus kisutch use a glacial river-fed estuary based on examination of spatial and seasonal variability in patterns of abundance, fish size, age structure, condition, and local habitat use. Fish abundance was greater in deeper channels with cooler and less variable temperatures, and these habitats were consistently occupied throughout the season. Variability in channel depth and water temperature was negatively associated with fish abundance. Fish size was negatively related to site distance from the upper extent of the tidal influence, while fish condition did not relate to channel location within the estuary ecotone. Our work demonstrates the potential this glacially-fed estuary serves as both transitional and rearing habitat for juvenile coho salmon during smolt emigration to the ocean, and patterns of fish distribution within the estuary correspond to environmental conditions.

A theoretical framework for analyzing the effect of external change on tidal dynamics in estuaries

NASA Astrophysics Data System (ADS)

CAI, H.; Savenije, H.; Toffolon, M.

2013-12-01

analytical solutions are applicable even in the upstream part of an estuary, where the influence of river discharge is remarkable. The proposed analytical solutions are transparent and practical, allowing a quantitative and qualitative assessment of human interventions (e.g., dredging, flow reduction) on tidal dynamics. Moreover, they are rapid assessment techniques that enable the users to set up a simple model and to understand the functioning of the system with a minimum of information required. The analytical model is illustrated in three large-scale estuaries with significant influence by human activities, i.e., the Scheldt estuary in the Netherlands, the Modaomen and the Yangtze estuaries in China. In these estuaries, the correspondence with observations is good, which suggests that the proposed model is a useful, yet realistic and reliable instrument for quick detection of the effect of human interventions on tidal dynamics and subsequent environmental issues, such as salt intrusion.

Impact of the operation of cascade reservoirs in upper Yangtze River on hydrological variability of the mainstream

NASA Astrophysics Data System (ADS)

Changjiang, Xu; Dongdong, Zhang

2018-06-01

As the impacts by climate changes and human activities are intensified, variability may occur in river's annual runoff as well as flood and low water characteristics. In order to understand the characteristics of variability in hydrological series, diagnosis and identification must be conducted specific to the variability of hydrological series, i.e., whether there was variability and where the variability began to occur. In this paper, the mainstream of Yangtze River was taken as the object of study. A model was established to simulate the impounding and operation of upstream cascade reservoirs so as to obtain the runoff of downstream hydrological control stations after the regulation by upstream reservoirs in different level years. The Range of Variability Approach was utilized to analyze the impact of the operation of upstream reservoirs on the variability of downstream. The results indicated that the overall hydrologic alterations of Yichang hydrological station in 2010 level year, 2015 level year and the forward level year were 68.4, 72.5 and 74.3 % respectively, belonging to high alteration in all three level years. The runoff series of mainstream hydrological stations presented variability in different degrees, where the runoff series of the four hydrological stations including Xiangjiaba, Gaochang and Wulong belonged to high alteration in the three level years; and the runoff series of Beibei hydrological station in 2010 level year belonged to medium alteration, and high alteration in 2015 level year and the forward level year. The study on the impact of the operation of cascade reservoirs in Upper Yangtze River on hydrological variability of the mainstream had important practical significance on the sustainable utilization of water resources, disaster prevention and mitigation, safe and efficient operation and management of water conservancy projects and stable development of the economic society.

A predictive model for floating leaf vegetation in the St. Louis River Estuary

EPA Science Inventory

In July 2014, USEPA staff was asked by MPCA to develop a predictive model for floating leaf vegetation (FLV) in the St. Louis River Estuary (SLRE). The existing model (Host et al. 2012) greatly overpredicts FLV in St. Louis Bay probably because it was based on a limited number of...

Variation of phytoplankton community structure from the Pearl River estuary to South China Sea.

PubMed

Jiang, Zhao-Yu; Wang, You-Shao; Cheng, Hao; Sun, Cui-Ci; Wu, Mei-Lin

2015-10-01

The Pearl River is located in the northern part of South China Sea. The environment of the Pearl River estuary (PRE) is significantly impacted by nutrients from anthropogenic activities. Along the anthropogenic pollution gradient from the PRE to South China Sea, the phylogenetic diversity and biomass of phytoplankton was examined in relation to physic-chemical variables. The richness of rbcL gene was higher in the open sea than the estuary, while the concentration of chlorophyll a (Chl a) was higher in the estuary than in the open sea. The cluster analysis of the sequences data resulted in seven phytoplankton community types and the dominant species of phytoplankton changed from Cryptophytes and Diatoms to Prymnesiophytes and Diatoms along the gradient. The community structure of phytoplankton was shaped by nutrients and salinity. The phytoplankton biomass was significantly positively affected by phosphorus, nitrite and ammonium (P < 0.01) but negatively by salinity (P < 0.05); the phytoplankton diversity was highly positively affected by salinity (P < 0.05) but negatively by silicate and nitrate (P < 0.01; P < 0.05, respectively). Anthropogenic activities played a critical role in the phytoplankton distribution and biomass of the study area. Further research is necessary to reveal the influence mechanism of environmental factors on the phytoplankton.

Latest Holocene evolution and human disturbance of a channel segment in the Hudson River Estuary

USGS Publications Warehouse

Klingbeil, A.D.; Sommerfield, C.K.

2005-01-01

The latest Holocene sedimentary record of a cohesive channel and subtidal shoal in the lower Hudson River Estuary was examined to elucidate natural (sea-level rise, sediment transport) and anthropogenic (bulkheading, dredging) influences on the recent morphodynamic evolution of the system. To characterize the seafloor and shallow subbottom, ??? 100 km of high-resolution seismic reflection profiles (chirp) were collected within a 20-km reach of the estuary and correlated with sediment lithologies provided by eight vibracores recovered along seismic lines. Sediment geochronology with 137Cs and 14C was used to estimate intermediate and long-term sedimentation rates, respectively, and historical bathymetric data were analyzed to identify regional patterns of accretion and erosion, and to quantify changes in channel geometry and sediment volume. The shoal lithosome originated around 4 ka presumably with decelerating eustatic sea level rise during the latest Holocene. Long-term sedimentation rates on the shoal (2.3-2.6 mm/yr) are higher than in the channel (2 mm/yr) owing to hydrodynamic conditions that preferentially sequester suspended sediment on the western side of the estuary. As a result, the shoal accretes oblique to the principal axis of tidal transport, and more rapidly than the channel to produce an asymmetric cross-section. Shoal deposits consist of tidally bedded muds and are stratified by minor erosion surfaces that seismic profiles reveal to extend for 10s of meters to kilometers. The frequency and continuity of these surfaces suggest that the surficial shoal is catastrophically stripped on decadal-centennial time scales by elevated tidal flows; tidal erosion maintains the shoal at a uniform depth below sea level and prevents it from transitioning to an intertidal environment. Consequently, the long-term sedimentation rate approximates the rate of sea-level rise in the lower estuary (1-3 mm/yr). After the mid 1800s, the natural geometry of the lower Hudson

Sedimentary Facies and Stratigraphy of the Changjiang (Yangtze River) Delta

NASA Astrophysics Data System (ADS)

Dalrymple, R. W.; Zhang, X.; Lin, C. M.

2017-12-01

A disproportionate number of the world's largest deltas are tide-dominated or strongly tide-influenced, in part because the low gradient of these rivers allows the tide to penetrate far inland, generating strong tidal currents at the river mouth. These deltas also tend to be mud-dominated because a significant fraction of the bedload is trapped farther inland. Despite their great importance as sediment depo-centers, as analogues for ancient sedimentary successions, and as areas of intense human occupation, they are the most poorly understood coastal system. The Changjiang (Yangtze River), the 4th largest river in the world in terms of sediment discharge, is one such tide-dominated system, with a mean tidal range of 2.7 m and tidal-current speeds of 1 m/s at its mouth. It shows a fairly typical series of low-relief channels and bars in the mouth-bar area and passes seaward and down-drift into a coastal mud belt that extends 800 km to the south of the river mouth. The deposits from both the transgressive-phase and modern delta are all dominated by mud, except for the fluvial-channel deposits that are clean sand. Channel-floor deposits in areas with appreciable tidal influence contain abundant fluid-mud layers (1-3 cm thick), intercalated with relatively coarse sand; such mud layers show evidence of tidal cyclicity. The overlying tidal-bar deposits commonly become sandier upward because of the upward loss of fluid-mud layers. The tidal channels and bars that characterize the mouth-bar and delta-front area are dominated by randomly organized structureless mud layers, 5-30 cm thick, that are interpreted to be storm-generated fluid-mud deposits. These mud layers become less abundant upward, generating upward-sanding successions. These facies are very similar to those seen in the Amazon and Fly River deltas, suggesting that this is a common motif, and indicating the importance of fluid mud in the dynamics of such systems. Facies proximality can be determined by careful

Exhumation history of the Anqing Orefield in the Lower Yangtze River Metallogenic Belt: Evidence from apatite fission-track thermochronology

NASA Astrophysics Data System (ADS)

Li, X.; Yang, X.

2017-12-01

The Lower Yangtze River Metallogenic Belt (LYRMB) is one of the most important Cu-Au-Fe polymetallic belts in China. These deposits along the Yangtze River region have been related to the Yanshanian intrusive rocks in the Mesozoic. The Anqing orefield is located in the northwestern Anqing, southwestern Anhui Province, eastern China, along the Lower Yangtze River Belt. Here, we report new apatite fission-track (AFT) thermochronology of the granitoids ( 130 Ma for zircon U-Pb age) associated with the Anqing orefields to reveal the exhumation history of the Anqing orefields in LYRMB, eastern China. AFT ages from 54.4±2.1 to 63.9±3.4 Ma with mean measured track lengths between 12.4±1.8 and 13.1±1.4 μm, were obtained for the granitoids sampled from the ore fields in the Anqing orefield, and AFT age of 36.3±1.3 Ma with mean track length of 12.3±2.3μm for the granitoids adjacent to the south Tan-Lu fault. A long, slow exhumation ( 60-15 Ma), and a short, rapid tectonic exhumation (15-0 Ma) have been identified in the study region based on the AFT data and modeling results for the samples from the ore fields. The results show that the granitoids underwent roughly similar cooling, and inferred exhumation pattern. Assuming a steady-state paleogeothermal gradient of 35ºC/km founded on geological setting, the exhumations of 570 m and 1140 m, were achieved in the Anqing orefield, during 60-15 Ma and 15-0 Ma, respectively. Further, the AFT age of the granitoids adjacent to the south Tan-Lu fault is less than the AFT ages of the granitoids associated with the ore fields, possibly owing to the activation of the Tan-Lu fault in the Cenozoic. The exhumation history of the Anqing orefields may be closely response to the Pacific Plate subduction in the Cenozoic, which could be implications for the preservation potential of ore bodies in the Anqing orefield. This work is supported by the National Natural Science Foundation of China (41372227), and the DREAM project of MOST

Modeled long-term changes of DIN:DIP ratio in the Changjiang River in relation to Chl-α and DO concentrations in adjacent estuary

NASA Astrophysics Data System (ADS)

Wang, Jianing; Yan, Weijin; Chen, Nengwang; Li, Xinyan; Liu, Lusan

2015-12-01

In the past four decades (1970-2013), nitrogen and phosphorous inputs to the Changjiang River basin, mainly from human activities, have increased 3-fold and 306-fold, respectively. The riverine nutrient fluxes to the estuary have also grown exponentially. Dissolved inorganic nitrogen (DIN) and dissolved inorganic phosphorous (DIP) fluxes of the Changjiang River increased by 338% and 574% during 1970-2013 period, and red tides and benthic hypoxia have been observed in the outflow region of the Changjiang River in the East China Sea (ECS). We assumed that time series changes in the DIN:DIP ratio from the Changjiang River could have a significant impact on Chlorophyll-α (Chl-α) concentration in the surface sea water and dissolved oxygen (DO) concentration in the bottom sea water of the Changjiang estuary. Our study showed that the DIN:DIP ratio from the Changjiang River increased from 76 to 384 between 1970 and 1985, and decreased from 255 to 149 between 1986 and 2013. The observed Chl-α concentration increased by 146% from 1992 to 2010 in the Changjiang estuary, and was negatively related to the DIN:DIP ratio in 1992-2010. Bottom sea water DO concentration decreased by 24.6% during 1992-2010 and a "low oxygen zone" (122°∼123°E, 32°∼33°N) was observed during summer since 1999. The anthropogenically enhanced nutrient inputs dominated river DIN and DIP fluxes and influenced Chl-α concentrations as well as bottom DO concentrations in the estuary. Scenarios emphasizing global collaboration and proactive environmental problem-solving may result in reductions in the river nutrient exports and in Chl-α and DO concentration in the Changjiang estuary by 2050.

[Residues and potential ecological risk assessment of metal in sediments from lower reaches and estuary of Pearl River].

PubMed

Xie, Wen-Ping; Wang, Shao-Bing; Zhu, Xin-Ping; Chen, Kun-Ci; Pan, De-Bo; Hong, Xiao-You; Yin, Yi

2012-06-01

In order to investigate the heavy metal concentrations and their potential ecological risks in surface sediments of lower reaches and estuary of Pearl River, 21 bottom sediment samples were collected from lower reaches and estuary of Pearl River. Total contents of Cr, Mn, Fe, Co, Ni, Cu, Zn, As, Se, Cd, Sb, Pb and Hg in these samples were measured by the inductively coupled plasma mass spectrometry (ICP-MS) and the atomic fluorescence spectrometry (AFS) and using the index of geoaccumulation and the potential ecological risk index to evaluate the pollution degree of heavy metals in the sediments. Results indicated that the concentration of total Fe and total Mn were 41658.73 and 1104.73 mg x kg(-1) respectively and toxic trace metals, such as Cr, Co, Ni, Cu, Zn, As, Se, Cd, Sb, Pb and Hg were 86.62, 18.18, 54.10, 80.20, 543.60, 119.55, 4.28, 10.60, 20.26, 104.58 and 0.520 mg x kg(-1). The descending order of pollution degree of various metals is: Cd > As approximately Zn > Hg > Pb approximately Cu approximately Cr, while the single potential ecological risk followed the order: Cd > Hg > As > Cu > Pb > Zn > Cr. The pollution extent and potential ecological risk of Cd were the most serious among all heavy metals. The distribution pattern of Cd individual potential ecological risk indices is exactly the same as that of general potential ecological risk indices for all heavy metals. Clustering analysis indicates that the sampling stations may be classified into five groups which basically reflected the characteristics of the heavy metal contamination and sedimentation environments along the different river reaches in lower reaches and estuary of Pearl Rive. In general, the serious heavy metal pollution and the high potential ecological risk existed in three river reaches: Chengcun-Shawan, Chengcun-Shundegang and Waihai-Hutiaomen. The pollution degree and potential ecological risk are higher in related river reaches of Beijiang than that in other lower reaches and

A cellular automata model for population expansion of Spartina alterniflora at Jiuduansha Shoals, Shanghai, China

NASA Astrophysics Data System (ADS)

Huang, Hua-mei; Zhang, Li-quan; Guan, Yu-juan; Wang, Dong-hui

2008-03-01

Biological invasion has received considerable attention recently because of increasing impacts on local ecosystems. Expansion of Spartina alterniflora, a non-native species, on the intertidal mudflats of Jiuduansha Shoals at the Yangtze River Estuary is a prime example of a spatially-structured invasion in a relatively simple habitat, for which strategic control efforts can be modeled and applied. Here, we developed a Cellular Automata (CA) model, in conjunction with Remote Sensing and Geographical Information Systems, to simulate the expanding process of S. alterniflora for a period of 8 years after being introduced to the new shoals, and to study the interactions between spatial pattern and ecosystem processes for the saltmarsh vegetation. The results showed that the CA model could simulate the population dynamics of S. alterniflora and Phragmites australis on the Jiuduansha Shoals successfully. The results strongly support the hypothesis of space pre-emption as well as range expansion with simple advancing wave fronts for these two species. In the Yangtze River Estuary, the native species P. australis shares the same niche with the exotic species S. alterniflora. However, the range expansion rate of P. australis was much slower than that of S. alterniflora. With the accretion of the Jiuduansha Shoals due to the large quantity of sediments deposited by the Yangtze River, a rapid range expansion of S. alterniflora is predicted to last for a long period into future. This study indicated the potential for this approach to provide valuable insights into population and community ecology of invasive species, which could be very important for wetland biodiversity conservation and resource management in the Yangtze River Estuary and other such impacted areas.

Last century seabed morphodynamics of the Magra River estuary (Western Mediterranean Sea)

NASA Astrophysics Data System (ADS)

Pratellesi, Marta; Ivaldi, Roberta; Ciavola, Paolo; Sinapi, Luigi

2016-04-01

The estimation of morphological and volumetric changes of the delta system at the mouth of the Magra River is presented in this paper using bathymetric and sedimentological data. The data series were collected during several hydro-oceanographic surveys carried out from 1882 to 2014, processed following the hydrographic international standards and stored in the Italian Navy Hydrographic Institute database. In particular, bathymetric data characterized by the same standard and accuracy were collected using different devices such as sounding lines, single-beam and multi-beam acoustic system. This research compares Digital Terrain Models (DTMs), derived from highly accurate bathymetric data and covering different time scales (secular, half-century and decade) in order to assess and quantify the seabed morphodynamics in relation with the river sedimentary budget. The methodology and data exploitation consist mainly in the production of DTMs to study the elevation change, two-dimensional and three dimensional maps, cross-sections of the seabed, difference surfaces and computation of net volumes as well as an historical sedimentological map. These products are also an useful contribution to the aim of EU RISC-KIT Project. The results of the analysis highlight changes in the geometry of the Magra River mouth, of the coastal profile and bottom features primarily due to variations of the sedimentary budget and secondarily to wave dynamics. This behaviour is characterized by evident river mouth and coastal retreat, beach erosion and sediment bars decay and net accretion under periods of high river sediment discharge and elongate bar formation during relatively fair conditions. In the last century the main change is constituted by the disappearance of the typical constructive seabed delta morphology and the transformation into the current small estuary, with microtidal condition. This small estuary has an upper sector where river processes, sediments and bedforms dominate, a

Integrated magnetostratigraphy and lithostratigraphy of five cores in Yangtze delta, China : significance of sedimentary evolution

NASA Astrophysics Data System (ADS)

Peng, Jie; Yang, XiaoQiang; Qiang, XiaoKe; Liu, YeBo; Zhou, QiXian

2017-04-01

The sedimentary history and characteristics of the Yangtze delta help us understand the tectonic evolution and geological formation process in the Eastern coastal area of China since the Cenozoic Era. Previous chronology of sediments in this area are not detailed or precise. Furthermore, when the delta area reached the maximum is still debatable. Palaeomagnetic polarity reversal and excursions, AMS14C dating, optically stimulated luminescence (OSL) dating, and the hard clay marker layer analysis were integrated to establish the chronostratigraphic framework of five drilling cores from the south Yangtze delta. Results from the bottom part of core CSB6 suggested Gauss normal polarity chron, an age of more than about 2600 ka. The other four cores showed initial deposition time between 200-60 ka B.P., significantly later than CSB6. We infer the reason is that CSB6 locating in the Changxin-Fenghua Fracture. Combined with data from referenced magnetostratigraphic cores in the Yangtze River Delta, we suggest that tectonic movement resulted in a much longer depositional age in some parts of the Yangtze River Delta and influenced the sedimentary characteristics of thick (North) to thin (South) and thick (East) to thin (West). In conclusion, a relatively wide range of deposition in the Yangtze River Delta occurred since about 200 ka B.P. The deposition of fine particles (clay-silt), which was controlled by slow tectonic subsidence and sea-level changes, expanded to the whole delta region after about 60 ka B.P. We propose that this time scale maybe used for further study on the evolution of the Yangtze delta's paleoclimate and paleoenvironment. References [1]Peng J,Yang X Q,Qiang X K,et al.Magnetostratigraphy characteristics of several cores around the Qiantang River mouth and its significance.Chinese J.Geophys.(in Chinese),2016,59(8):2949-2964. [2]Li C X, Chen Q Q, Zhang J Q,et al. Stratigraphy and paleoenvironmental changes in the Yangtze Delta during the Late Quaternary

Antibiotics in water and sediments of rivers and coastal area of Zhuhai City, Pearl River estuary, south China.

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