Contamination profiles of perfluoroalkyl substances in five typical rivers of the Pearl River Delta region, South China.

Science.gov (United States)

Pan, Chang-Gui; Ying, Guang-Guo; Liu, You-Sheng; Zhang, Qian-Qian; Chen, Zhi-Feng; Peng, Feng-Jiao; Huang, Guo-Yong

2014-11-01

A survey on contamination profiles of eighteen perfluoroalkyl substances (PFASs) was performed via high performance liquid chromatography-tandem mass spectrometry for surface water and sediments from five typical rivers of the Pearl River Delta region, South China in summer and winter in 2012. The total concentrations of the PFASs in the water phase of the five rivers ranged from 0.14 to 346.72 ng L(-1). The PFAS concentrations in the water phase were correlated positively to some selected water quality parameters such as chemical oxygen demand (COD) (0.7913) and conductivity (0.5642). The monitoring results for the water samples showed significant seasonal variations, while those for the sediment samples showed no obvious seasonal variations. Among the selected 18 PFASs, perfluorooctane sulfonic acid (PFOS) was the dominant PFAS compound both in water and sediment for two seasons with its maximum concentration of 320.5 ng L(-1) in water and 11.4 ng g(-1) dry weight (dw) in sediment, followed by perfluorooctanoic acid (PFOA) with its maximum concentration of 26.48 ng L(-1) in water and 0.99 ng g(-1) dw in sediment. PFOS and PFOA were found at relatively higher concentrations in the Shima River and Danshui River than in the other three rivers (Xizhijiang River, Dongjiang River and Shahe River). The principal component analysis for the PFASs concentrations in water and sediment separated the sampling sites into two groups: rural and agricultural area, and urban and industrial area, suggesting the PFASs in the riverine environment were mainly originated from industrial and urban activities in the region. Copyright © 2014 Elsevier Ltd. All rights reserved.

Linear alkylbenzenes in riverine runoff of the Pearl River Delta (China) and their application as anthropogenic molecular markers in coastal environments

International Nuclear Information System (INIS)

Ni Honggang; Lu Fenghui; Wang Jizhong; Guan Yufeng; Luo Xianlin; Zeng, Eddy Y.

2008-01-01

The average concentrations of ΣLABs (sum of C 10 -C 13 -LABs) in runoff samples collected from the eight major riverine outlets of the Pearl River Delta (PRD) of China ranged from 1.4 to 6124 ng/L in the dissolved phase and from 0.01 to 11.4 μg/g dry weight in the particulate phase during March 2005-February 2006. The annual riverine flux of ΣLABs from the PRD to the coastal ocean was estimated at approximately 14 tons/yr. The inventories of ΣLABs in agricultural lands of Guangdong Province ranged from 313 to 1825 kg/yr. The early and late rice fields were the major sink of LABs, accounting for approximately 68% of total LABs inventory in agricultural lands. The social-economically estimated annual discharge of LABs from household detergents in the PRD was ∼696 tons/yr, more than an order of magnitude higher than that estimated from field measurements (about 14 tons/yr), which was attributed to several factors. - Occurrence of LABs in riverine runoff of the Pearl River Delta (China) was examined

Aerosol profiles determined with lidar and sun-photometer over the Pearl River Delta, China.

Science.gov (United States)

Heese, B.; Althausen, D.; Bauditz, M.; Deng, R.; Bao, R.; Li, Z.

2012-04-01

The priority program "Megacities-Megachallenge - Informal Dynamics of Global Change" is a large interdisciplinary project funded by the German Research Foundation (DFG). One of the subproject deals with mega-urbanisation in the Pearl River Delta, South-China, with special respect to particulate air pollution and public health. In the frame of this subproject the vertical distribution of aerosol optical properties are investigated by measurements with the multiwavelength-Raman-polarization lidar PollyXT of the IfT. The instrument can measure the particle backscatter coefficient at 355 nm, 532 nm, and 1064 nm, the particle extinction coefficients at 355 nm and 532 nm, and the particle linear depolarization ratio at 532 nm. These measurements are supported by a dual-polar sun photometer that provides height integrated data as the aerosol optical depth and the degree of linear depolarization. These instruments are placed at the East campus of the Sun Yat-sen University in Guangzhou, China. Guangzhou and the Pearl River Delta is a developing area with currently around 11 Million inhabitants. The measurements started in November 2011 and are supposed to continue for at least half a year covering the late autumn and winter season and parts of the spring season. Extensions of the measurements towards a whole seasonal cycle are planned. Thus, different meteorological conditions will lead to particle transport from several source regions. Different aerosol types are expected to be observed during the measurement period: urban particles from local and regional sources as well as dust from the deserts in Central Asia. The observed particles can be distinguished by analyzing their optical properties at several wavelengths. In particular, the depolarization measurements from both instruments promise a better determination of the particle shape.

A gradient analysis on urban sprawl and urban landscape pattern between 1985 and 2000 in the Pearl River Delta, China

Science.gov (United States)

Dai, Erfu; Wu, Zhuo; Du, Xiaodian

2017-04-01

Urbanization is an irreversible trend worldwide, especially in rapidly developing China. Accelerated urbanization has resulted in rapid urban sprawl and urban landscape pattern changes. Quantifying the spatiotemporal dynamics of urban land use and landscape pattern not only can reveal the characteristics of social transfer and economic development, but also can provide insights into the driving mechanisms of land use changes. In this study, we integrated remote sensing (RS), geographic information system (GIS), landscape metrics, and gradient analysis to quantitatively compare the spatiotemporal dynamics of land use, urban sprawl, and landscape pattern for nine cities in the Pearl River Delta from 1985‒2000. For the whole study region, urbanization was obvious. The results show an increase in urban buildup land and shrinkage of cropland in the Pearl River Delta. However, the nine cities differed greatly in terms of the process and magnitude of urban sprawl for both the spatial and temporal dimensions. This was most evident for the cities of Guangzhou and Shenzhen. Gradient analysis on urban landscape changes could deepen understanding of the stages of urban development and provide a scientific foundation for future urban planning and land management strategies in China.

Distribution of polycyclic aromatic hydrocarbons in thirty typical soil profiles in the Yangtze River Delta region, east China

International Nuclear Information System (INIS)

Ping, L.F.; Luo, Y.M.; Zhang, H.B.; Li, Q.B.; Wu, L.H.

2007-01-01

Polycyclic aromatic hydrocarbons (PAHs) were quantified in 30 soil profiles from the Yangtze River Delta Region, in east China. Relative concentrations of PAH compounds with different benzene rings and ratios of fluoranthene to fluoranthene plus pyrene and benz(a)anthracene to benz(a)anthracene plus chrysene were used to identify the possible sources of soil PAHs. Total concentrations of 15 PAHs in topsoils ranged from 8.6 to 3881 μg kg -1 with an average of 397 μg kg -1 . Half of the soil samples were considered to be contaminated with PAHs (>200 μg kg -1 ) and two sampling sites were heavily polluted by PAHs with concentrations >1000 μg kg -1 . Phenanthrene was found in soils below a depth of 100 cm in half of the sampling sites, but the detectable ratio of benzo(a)pyrene decreased sharply from 100% in topsoil to 0 in the 4th horizon. - The information was provided on levels, distributions, and possible sources of PAHs in the soils of Yangtze River Delta area

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

Science.gov (United States)

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.

Tidal controls on river delta morphology

Science.gov (United States)

Hoitink, A. J. F.; Wang, Z. B.; Vermeulen, B.; Huismans, Y.; Kästner, K.

2017-09-01

River delta degradation has been caused by extraction of natural resources, sediment retention by reservoirs, and sea-level rise. Despite global concerns about these issues, human activity in the world’s largest deltas intensifies. Harbour development, construction of flood defences, sand mining and land reclamation emerge as key contemporary factors that exert an impact on delta morphology. Tides interacting with river discharge can play a crucial role in the morphodynamic development of deltas under pressure. Emerging insights into tidal controls on river delta morphology suggest that--despite the active morphodynamics in tidal channels and mouth bar regions--tidal motion acts to stabilize delta morphology at the landscape scale under the condition that sediment import during low flows largely balances sediment export during high flows. Distributary channels subject to tides show lower migration rates and are less easily flooded by the river because of opposing non-linear interactions between river discharge and the tide. These interactions lead to flow changes within channels, and a more uniform distribution of discharge across channels. Sediment depletion and rigorous human interventions in deltas, including storm surge defence works, disrupt the dynamic morphological equilibrium and can lead to erosion and severe scour at the channel bed, even decades after an intervention.

Environmental lead pollution threatens the children living in the Pearl River Delta region, China.

Science.gov (United States)

Chen, Jianmin; Tong, Yongpeng; Xu, Jiazhang; Liu, Xiaoli; Li, Yulan; Tan, Mingguang; Li, Yan

2012-09-01

The objective of this study is to determine children's blood lead levels and identify sources of lead exposure. Childhood lead exposure constitutes a major pediatric health problem today in China. A blood lead screening survey program for children in the age group of 2-12 years residing in Pearl River Delta region, south of China, was carried out from Dec 2007 to Jan 2008. Blood lead levels and lead isotope ratios of a total of 761 participants were assessed by inductively coupled plasma mass spectroscopy. Measurements of urban environmental samples for source identification of children lead exposure were also performed. The geometric mean value of the children's blood lead levels was 57.05 μg/L, and 9.6% of them were higher than 100 μg/L. The blood lead levels were still much higher than those in developed countries. Based on the data of environmental lead source inventories, lead isotopic tracing revealed that there is about 6.7% past used gasoline Pb embedded in Shenzhen residential dust and about 15.6% in Guangzhou dust, respectively.

Corporate social capital, market orientation, organizational learning and service innovation performance: an empirical survey in the Pearl river delta of China

OpenAIRE

Jian, Zhaoquan; Zhou, Yu Lu

2015-01-01

Purpose: Service innovation performance (SIP) is an important driver of growth and wealth of service firms in wide range of industries. Yet, few research studies have been done to explore the influencing factors. The purpose of this study intends to identify the impacts of corporate social capital, market orientation and organizational learning on service innovation in the Pearl River Delta of China.Design/methodology/approach: The paper mainly adopted the empirical research. A Structure Equa...

Heavy metals and polychlorinated biphenyls (PCBs) sedimentation in the Lianhua Mountain Reservoir, Pearl River Delta, China.

Science.gov (United States)

Huang, Jingyu; Amuzu-Sefordzi, Basil; Li, Ming

2015-05-01

The Pearl River Delta is one of the biggest electronics manufacturing regions in the world. Due to the presence of abandoned industrial sites and the proliferation of large-scale electronics companies in the past four decades, it is therefore imperative to investigate the extent of heavy metals and polychlorinated biphenyls (PCBs) contamination in the region. Spatial and temporal distribution of heavy metals (Cr, Cu, Ni, Pb, and Zn) and PCBs (PCB28, PCB52, PCB101, PCB118, PCB138, PCB153, and PCB180) in the Lianhua Mountain reservoir in the Pearl River Delta, Dongguan City, China were examined based on a sedimentary profile analysis. Higher concentrations of the heavy metals detected were recorded in bottom sediments whereas 70% of the detected PCBs recorded maximum concentrations in top sediments. The geo-accumulation indices (Igeo) indicate that the study area is uncontaminated to moderately contaminated. Also, the integrated pollution indices (IPI) were above 1, except Pb, which shows that the study area is contaminated with heavy metals from anthropogenic sources. The concentrations of individual heavy metals and PCBs over a period of 60 years were also analyzed in order to establish a historical trend of pollution in the study area. This study provides baseline information on the level and historical trend of heavy metals and PCBs pollution in the study area.

Role of sectoral and multi-pollutant emission control strategies in improving atmospheric visibility in the Yangtze River Delta, China

International Nuclear Information System (INIS)

Huang, Kan; Fu, Joshua S.; Gao, Yang; Dong, Xinyi; Zhuang, Guoshun; Lin, Yanfen

2014-01-01

The Community Multi-scale Air Quality modeling system is used to investigate the response of atmospheric visibility to the emission reduction from different sectors (i.e. industries, traffic and power plants) in the Yangtze River Delta, China. Visibility improvement from exclusive reduction of NO x or VOC emission was most inefficient. Sulfate and organic aerosol would rebound if NO x emission was exclusively reduced from any emission sector. The most efficient way to improve the atmospheric visibility was proven to be the multi-pollutant control strategies. Simultaneous emission reductions (20–50%) on NO x , VOC and PM from the industrial and mobile sectors could result in 0.3–1.0 km visibility improvement. And the emission controls on both NO x (85%) and SO 2 (90%) from power plants gained the largest visibility improvement of up to 4.0 km among all the scenarios. The seasonal visibility improvement subject to emission controls was higher in summer while lower in the other seasons. -- Highlights: • Atmospheric visibility in the Yangtze River Delta is modeled and evaluated. • Responses of visibility changes to various emission reduction scenarios are compared. • Sulfate aerosol will increase if only NO x emission is reduced. • The multi-pollutant control strategy is most efficient for improving visibility. -- Responses of visibility changes to various emission reduction scenarios are compared. The multi-pollutant control strategy is most efficient for improving visibility in YRD, China

Organochlorine pesticides and polychlorinated biphenyls in riverine runoff of the Pearl River Delta, China: Assessment of mass loading, input source and environmental fate

International Nuclear Information System (INIS)

Guan Yufeng; Wang Jizhong; Ni Honggang; Zeng, Eddy Y.

2009-01-01

A large-scale sampling program was conducted to simultaneously collect water samples at the eight major riverine runoff outlets of the Pearl River Delta (PRD), South China to assess the importance of riverine runoff in transporting anthropogenic pollutants from terrestrial sources to the coastal ocean. The concentrations of Σ 21 OCPs (sum of 21 OCP components) and Σ 20 PCBs (sum of 20 PCB congeners) were 2.57-41.2 and 0.12-1.47 ng/L, respectively. Compositional distributions of DDTs suggested the possibility of new input sources in the study area, but contributions from dicofol seemed considerably low. The annual inputs of Σ 21 OCPs and Σ 20 PCBs were 3090 and 215 kg, with those of total HCHs and DDTs being 1110 and 1020 kg, respectively. A mass balance consideration indicated that riverine runoff is the major mode carrying OCPs from the PRD to the coastal ocean, and the majority of OCPs is further dissipated to open seas. - Mass loadings, input sources and environmental fate of organochlorine pesticides and polychlorinated biphenyls in riverine runoff of the Pearl River Delta, China are assessed

River Delta Subsidence Measured with Interferometric Synthetic Aperture Radar (InSAR)

Science.gov (United States)

Higgins, Stephanie

This thesis addresses the need for high-resolution subsidence maps of major world river deltas. Driven by a combination of rising water, sediment compaction, and reduced sediment supply due to damming and flood control, many deltas are sinking relative to sea level. A lack of data constraining rates and patterns of subsidence has made it difficult to determine the relative contributions of each factor in any given delta, however, or to assess whether the primary drivers of land subsidence are natural or anthropogenic. In recent years, Interferometric Synthetic Aperture Radar (InSAR) has emerged as a satellite-based technique that can map ground deformation with mm-scale accuracy over thousands of square kilometers. These maps could provide critical insight into the drivers of subsidence in deltas, but InSAR is not typically applied to non-urban delta areas due to the difficulties of performing the technique in wet, vegetated settings. This thesis addresses those difficulties and achieves high-resolution measurements of ground deformation in rural deltaic areas. Chapter 1 introduces the processes that drive relative sea level rise in river deltas and investigates open questions in delta subsidence research. Chapter 2 assesses the performance of InSAR in delta settings and reviews interferogram generation in the context of delta analysis, presenting delta-specific processing details and guiding interpretation in these challenging areas. Chapter 3 applies Differential (D-) InSAR to the coast of the Yellow River Delta in China. Results show that subsidence rates are as high as 250 mm/y due to groundwater extraction at aquaculture facilities, a rate that exceeds local and global average sea level rise by nearly two orders of magnitude and suggests a significant hazard for Asian megadeltas. Chapter 4 applies interferometric stacking and Small Baseline Subset (SBAS)-InSAR to the Ganges-Brahmaputra Delta, Bangladesh. Results show that stratigraphy controls subsidence in

Research on the Synergy Degree of China Yangtze River Delta Region Technology Innovation System Evolution from the Perspective of Technology Innovation Chain

Directory of Open Access Journals (Sweden)

Xu Bin Feng

2014-08-01

Full Text Available Abstract: This paper divides technology innovation system into research and development input subsystem, technology research and development subsystem and technology application subsystem from the perspective of technology innovation chain, combining with the system theory. Then selects the corresponding ordinal variables, makes an empirical analysis to the synergy degree of Yangtze River delta regional technology innovation system evolution by complex system synergy degree model which based on the data of 2002-2009. The results show that the development of synergy degree of the technology innovation system appears a rising trend and the technology application subsystem is the key factor of direction and degree of synergy development in the evolution process of regional technology innovation system in the Yangtze River Delta of China. Finally, this paper analyzes the characteristics and causes of synergy degree’s evolution, and puts forward the corresponding policy recommendations to different problems.

Growth laws for sub-delta crevasses in the Mississippi River Delta

Science.gov (United States)

Yocum, T. A.; Georgiou, I. Y.; Straub, K. M.

2017-12-01

River deltas are threatened by environmental change, including subsidence, global sea level rise, reduced sediment inputs and other local factors. In the Mississippi River Delta (MRD) these impacts are exemplified, and have led to proposed solutions to build land that include sediment diversions to reinitiate the delta cycle. Deltas were studied extensively using numerical models, theoretical and conceptual frameworks, empirical scaling relationships, laboratory models and field observations. But predicting the future of deltas relies on field observations where for most deltas data are still lacking. Moreover, empirical and theoretical scaling laws may be influenced by the data used to develop them, while laboratory deltas may be influenced by scaling issues. Anthropogenic crevasses in the MRD are large enough to overcome limitations of laboratory deltas, and small enough to allow for rapid channel and wetland development, providing an ideal setting to investigate delta development mechanics. Here we assessed growth laws of sub-delta crevasses (SDC) in the MRD, in two experimental laboratory deltas (LD - weakly and strongly cohesive) and compared them to river dominated deltas worldwide. Channel and delta geometry metrics for each system were obtained using geospatial tools, bathymetric datasets, sediment size, and hydrodynamic observations. Results show that SDC follow growth laws similar to large river dominated deltas, with the exception of some that exhibit anomalous behavior with respect to the frequency and distance to a bifurcation and the fraction of wetted delta shoreline (allometry metrics). Most SDC exhibit a systematic decrease of non-dimensional channel geometries with increased bifurcation order, indicating that channels are adjusting to decreased flow after bifurcations occur, and exhibit linear trends for land allometry and width-depth ratio, although geometries decrease more rapidly per bifurcation order. Measured distance to bifurcations in SDC

Urban Land Expansion and Structural Change in the Yangtze River Delta, China

Directory of Open Access Journals (Sweden)

Jinlong Gao

2015-07-01

Full Text Available Urban development in China has attracted considerable scholarly attention. However, more work is still needed to examine and understand the mechanisms of urban land expansion, especially within the context of globalization/marketization, decentralization and urbanization. This paper analyzes urban land expansion and structural changes in the Yangtze River Delta (YRD. We find that cities in the YRD are experiencing urban land expansion mainly characterized by the growth of residential and industrial land. The dominant characteristics of urban land expansion in cities have also varied within different development and administrative levels. Based on our conceptual framework, we have used multi-models to investigate the driving forces of urban land expansion and structural changes in the YRD. The results reveal that six influencing factors—foreign direct investment (FDI, labor, government competition, institution, population, and job-housing relations—facilitate land use change in the economic transition process. However, their impacts differ in cities in different geographical locations, as well as with different administrative levels. Finally, this paper discusses policies to promote sustainable urban land use in the YRD.

Changes in the areal extents of the Athabasca River, Birch River, and Cree Creek Deltas, 1950-2014, Peace-Athabasca Delta, Canada

Science.gov (United States)

Timoney, Kevin; Lee, Peter

2016-04-01

Deltas form where riverborne sediment accumulates at the interface of river mouths and their receiving water bodies. Their areal extent is determined by the net effect of processes that increase their extent, such as sediment accumulation, and processes that decrease their extent, such as erosion and subsidence. Through sequential mapping and construction of river discharge and sediment histories, this study examined changes in the subaerial extents of the Cree Creek and Athabasca River Deltas (both on the Athabasca River system) and the Birch River Delta in northern Canada over the period 1950-2014. The purpose of the study was to determine how, when, and why the deltas changed in areal extent. Temporal growth patterns were similar across the Athabasca and Birch River systems indicative of a climatic signal. Little or no areal growth occurred from 1950 to 1968; moderate growth occurred between 1968 and the early to mid-1980s; and rapid growth occurred between 1992 and 2012. Factors that affected delta progradation included dredging, sediment supply, isostatic drowning, delta front bathymetry, sediment capture efficiency, and storms. In relation to sediment delivered, areal growth rates were lowest in the Athabasca Delta, intermediate in the Birch Delta, and highest in the Cree Creek Delta. Annual sediment delivery is increasing in the Cree Creek Delta; there were no significant trends in annual sediment delivery in the Birch and Athabasca Deltas. There was a lag of up to several years between sediment delivery events and progradation. Periods of delta progradation were associated with low water levels of the receiving basins. Predicted climate-change driven declines in river discharge and lake levels may accelerate delta progradation in the region. In the changing ecosystems of northeastern Alberta, inadequate monitoring of vegetation, landforms, and sediment regimes hampers the elucidation of the nature, rate, and causality of ecosystem changes.

Morphodynamics and Sediment Transport on the Huanghe (Yellow River) Delta: Work in Progress

Science.gov (United States)

Kineke, G. C.; Calson, B.; Chadwick, A. J.; Chen, L.; Hobbs, B. F.; Kumpf, L. L.; Lamb, M. P.; Ma, H.; Moodie, A. J.; Mullane, M.; Naito, K.; Nittrouer, J. A.; Parker, G.

2017-12-01

Deltas are perhaps the most dynamic of coastal landforms with competing processes that deliver and disperse sediment. As part of the NSF Coastal SEES program, an interdisciplinary team of scientists from the US and China are investigating processes that link river and coastal sediment transport responsible for morphodynamic change of the Huanghe delta- an excellent study site due to its high sediment load and long history of natural and engineered avulsions, that is, abrupt shifts in the river course. A fundamental component of the study is a better understanding of sediment transport physics in a river system that transports mostly silt. Through theory and data analysis, we find that fine-grained rivers fail to develop full scale dunes, which results in faster water flow and substantially larger sediment fluxes as compared to sandy rivers (e.g. the Mississippi River). We also have developed new models for sediment-size dependent entrainment that are needed to make longer term predictions of river sedimentation patterns. On the delta front, we are monitoring the high sediment flux to the coast, which results in steep foresets and ideal conditions for off-shore sediment delivery via gravity flows. These constraints on sediment transport are being used to develop new theory for where and when rivers avulse - including the effects of variable flood discharge, sediment supply, and sea level rise -and how deltas ultimately grow through repeated cycles of lobe development. Flume experiments and field observations are being used to test these models, both in the main channel of the Huanghe and in channels abandoned after historic avulsions. Abandoned channels and floodplains are now dominated by coastal sediment transport through a combination of wave resuspension and tidal transport, settling lag and reverse estuarine circulation. Finally, the field and laboratory tested numerical models are being used as inputs to define a cost curve for efficient avulsion management of

Polycyclic aromatic hydrocarbons in upstream riverine runoff of the Pearl River Delta, China: An assessment of regional input sources

International Nuclear Information System (INIS)

Zhang Kai; Liang Bo; Wang Jizhong; Guan Yufeng; Zeng, Eddy Y.

2012-01-01

Water samples collected from upstream tributaries of the Pearl River Delta (PRD) and from locations within the PRD (South China) were analyzed for 27 polycyclic aromatic hydrocarbons (PAHs). Average concentrations (aqueous plus particulate) of total 27 PAHs (Σ 27 PAH), 16 priority PAHs designated by the United States Environmental Protection Agency (USEPA) except naphthalene (Σ 15 PAH), and the seven carcinogenic PAHs (Σ 7 PAH) classified by the USEPA were 260 ± 410, 130 ± 310, and 15 ± 12 ng/L, respectively. Riverine PAHs were predominantly generated from coal and vegetation combustion, coke production, vehicle exhausts, and petroleum residues, accounting for 28%, 25%, 22% and 21%, respectively, on average. Upstream riverine fluxes of Σ 27 PAH and Σ 15 PAH amounted to 38.9 and 12.9 tons/year, respectively. The net contributions of Σ 27 PAH and Σ 15 PAH from sources within the PRD were estimated at 21.4 and 21.0 tons/year, respectively. - Highlights: ► Upstream PAH levels were lower than downstream PAHs and pose low ecological risk. ► Riverine PAHs are predominantly pyrogenic. ► Parent PAHs in Pearl River are mainly derived from within the PRD. ► The 15 priority PAHs were mainly generated within the Pearl River Delta. - The 15 priority PAHs are mainly generated within the PRD while the other 12 PAHs from upstream areas.

Tissue distribution of organochlorine pesticides in fish collected from the Pearl River Delta, China: Implications for fishery input source and bioaccumulation

International Nuclear Information System (INIS)

Guo Ying; Meng Xiangzhou; Tang Honglei; Zeng, Eddy Y.

2008-01-01

Fish tissues from different fishery types (freshwater farmed, seawater farmed and seawater wild) were analyzed for organochlorine pesticides (OCPs), with the aim to further our understanding of bioaccumulation, and reflect the state of different fishery environments. Significantly higher ΣOCP levels were found in seawater farmed fish than others, and among three freshwater farmed species, the lowest levels occurred in filter-feeding fish (bighead carp). Liver contained the highest ΣOCP levels, while no significant differences were found among other tissues. Among DDT components, p,p'-DDT was abundant in seawater fish, while for freshwater fish, p,p'-DDE was the predominant congeners, except for northern snakehead (34% for p,p'-DDE and 30% for p,p'-DDT). The new source of DDTs to freshwater fish ponds was partly attributed to dicofol, whereas sewage discharged from the Pearl River Delta and anti-fouling paint were likely the DDTs sources to seawater farmed fish. - Occurrence of organochlorine pesticides in fish tissues was examined to assess input sources and modes of bioaccumulation in the Pearl River Delta, China

Riverine inputs of polybrominated diphenyl ethers from the Pearl River Delta (China) to the coastal ocean.

Science.gov (United States)

Guan, Yu-Feng; Wang, Ji-Zhong; Ni, Hong-Gang; Luo, Xiao-Jun; Mai, Bi-Xian; Zeng, Eddy Y

2007-09-01

Riverine runoff is an important mode to transport anthropogenic pollutants from terrestrial sources to oceans. Polybrominated diphenyl ethers (PBDEs) were measured in riverine runoff samples from the eight major outlets within the Pearl River Delta (PRD), China, an economically fast developing region housing a vast number of electronics manufacturing and assembling plants. The sigma 17PBDEs (sum of 17 BDE congeners, i.e., BDE-28, -47, -66, -85, -99, -100, -138, -153, -154, -183, -196, -197, -203, -206, -207, -208, and -209) concentrations varied from 344 to 68,000 pg/L, with those of BDE-209, BDE-47, and BDE-99 being 335-65200, 3-143, and production of brominated fire retardants (approximately 10000 metric tons/year) and the annual riverine input of total PBDEs from the PRD, suggesting that the majority of PBDEs inventory has been accumulated from importation of e-wastes. Because of the continuous importation of e-wastes and strong demand for brominated fire retardants, the impact of PBDEs on China's and the world's environments is expected to persist for many years to come.

High aerosol load over the Pearl River Delta, China, observed with Raman lidar and Sun photometer

Science.gov (United States)

Ansmann, Albert; Engelmann, Ronny; Althausen, Dietrich; Wandinger, Ulla; Hu, Min; Zhang, Yuanghang; He, Qianshan

2005-07-01

Height-resolved data of the particle optical properties, the vertical extend of the haze layer, aerosol stratification, and the diurnal cycle of vertical mixing over the Pearl River Delta in southern China are presented. The observations were performed with Raman lidar and Sun photometer at Xinken (22.6°N, 113.6°E) near the south coast of China throughout October 2004. The lidar run almost full time on 21 days. Sun photometer data were taken on 23 days, from about 0800 to 1700 local time. The particle optical depth (at about 533-nm wavelength) ranged from 0.3-1.7 and was, on average, 0.92. Ångström exponents varied from 0.65-1.35 (for wavelengths 380 to 502 nm) and from 0.75-1.6 (for 502 to 1044 nm), mean values were 0.97 and 1.22. The haze-layer mean extinction-to-backscatter ratio ranged from 35-59 sr, and was, on average, 46.7 sr. The top of the haze layer reached to heights of 1.5-3 km in most cases.

Contamination of persistent organochlorines in sediments from Mekong River Delta, South Vietnam

Energy Technology Data Exchange (ETDEWEB)

Hung, Minh Nguyen; Kajiwara, Natsuko; Kunisue, Tatsuya; Subramanian, A.; Iwata, Hisato; Tanabe, Shinsuke [Ehime Univ., Matsuyama (Japan). Center for Marine Environmental Studies; Hung, Viet Pham [Hanoi National Univ., Hanoi (Viet Nam); Cach, Tuyen Bui [Univ. for Agriculture and Forestry, Hochiminh (Viet Nam)

2004-09-15

Mekong River is the longest river in southeastern Asia, which flows a distance of almost 4800 km from China through Myanmar, Thailand, Laos, Cambodia and Vietnam. The Mekong River basin with an area of nearly 800 thousand square kilometers is an important habitat for approximately 60 million people. Mekong River delta in South Vietnam, which is inhabited by about 20 million people, is one of the most highly productive agriculture lands in the world. Rice production is major economical sector in Mekong delta contributing half of the rice production in Vietnam - approximately 35 million tons annually. On the other hand, development of agriculture in Mekong delta raised some concern on environmental quality and disturbance on ecosystem. For example, intensive use of organochlorine (OC) insecticides such as DDTs, chlordanes, HCHs may lead to considerable residues in the agriculture land. Moreover, relative persistence of such chemicals together with natural processes like evaporation and run-off, might enhance their ubiquitous distribution in environment, food chains and eventually bio-accumulate in humans. In Vietnam, despite official ban on the usage of OCs on 1995, there have been evidences of recent uses of such chemicals, particularly DDT, throughout the country. It can be anticipated that similar situation may occur in Mekong River delta due to high population density and intensive agriculture activities in this region. Despite this fact, no comprehensive study, to evaluate the status of contamination by persistent OCs in this region, has been made in recent years. In this study, we collected sediments from different locations along Mekong River and determined the concentrations of persistent OCs such as DDTs, HCHs, CHLs, HCB and PCBs in order to elucidate the recent contamination status, their usage pattern as well as to evaluate potential pollution sources of these chemicals to the river.

Rapid Urbanization and Implications for Flood Risk Management in Hinterland of the Pearl River Delta, China: The Foshan Study

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Xiang-rong Wang

2008-03-01

Full Text Available The purpose of this paper is to examine the linkage between rapid urbanization and flood risk in the hinterlands of the Pearl River Delta, P.R. China. Foshan, a typical hinterland city in the Pearl River Delta region, was selected as a case study. Land use and cover change in Foshan during 1988-2003 was analyzed using remote sensing and geographic information system (GIS techniques. Furthermore, analysis on historical hydrological data during 1962-2005 was performed. Results show that rapid urbanization has resulted in losses of farmland, forest and shrub since 1988. In addition, in order to compensate or offset the loss of farmland due to rapid urban expansion, more than 30 % of the forest and 20 % of the shrub areas were transformed into farmlands. Inevitably, both the urban and agricultural lands increased the pressure on the drainage systems. Furthermore, over the past decades human activities such as dredging up the floodways, excavating sand and building water facilities in the rivers, significantly changed the hydrological conditions, and therefore impaired the rivers’ capacity to buffer floods. Lessons from the Foshan case implied that, in addition to natural processes, human activities driven by socio-economic factors should be considered responsible for the recently increasing level of flood risks. Both economically and environmentally, it is irrational and impractical to encourage encroachment of lands vulnerable to floods. It is also realistic and urgent to effectively prevent and control the adverse ecological consequences of urbanization and economic activities for building their wealth and prominence.

Rapid Urbanization and Implications for Flood Risk Management in Hinterland of the Pearl River Delta, China: The Foshan Study.

Science.gov (United States)

Zhang, Hao; Ma, Wei-Chun; Wang, Xiang-Rong

2008-03-28

The purpose of this paper is to examine the linkage between rapid urbanization and flood risk in the hinterlands of the Pearl River Delta, P.R. China. Foshan, a typical hinterland city in the Pearl River Delta region, was selected as a case study. Land use and cover change in Foshan during 1988-2003 was analyzed using remote sensing and geographic information system (GIS) techniques. Furthermore, analysis on historical hydrological data during 1962-2005 was performed. Results show that rapid urbanization has resulted in losses of farmland, forest and shrub since 1988. In addition, in order to compensate or offset the loss of farmland due to rapid urban expansion, more than 30 % of the forest and 20 % of the shrub areas were transformed into farmlands. Inevitably, both the urban and agricultural lands increased the pressure on the drainage systems. Furthermore, over the past decades human activities such as dredging up the floodways, excavating sand and building water facilities in the rivers, significantly changed the hydrological conditions, and therefore impaired the rivers' capacity to buffer floods. Lessons from the Foshan case implied that, in addition to natural processes, human activities driven by socio-economic factors should be considered responsible for the recently increasing level of flood risks. Both economically and environmentally, it is irrational and impractical to encourage encroachment of lands vulnerable to floods. It is also realistic and urgent to effectively prevent and control the adverse ecological consequences of urbanization and economic activities for building their wealth and prominence.

The Relationship between Urban Sprawl and Farmland Displacement in the Pearl River Delta, China

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Shiqiang Du

2013-12-01

Full Text Available China is rapidly urbanizing and will inevitably face trade-offs between promoting economic growth through further urbanization and protecting fertile farmland against accelerated urban expansion. This paper presents how this dilemma is being addressed in one of the most rapidly urbanizing regions in China, the Pearl River Delta (PRD, by means of assessing urban growth and farmland dynamic, as well as their complex relationships. Land use maps derived from Landsat imagery for 1990, 2000 and 2010 show a process of accelerated urban sprawl whereby built-up lands have more than quadrupled and scattered centers have merged into megacities. Nonetheless, the land use efficiency is considerably low and is declining relative to Hong Kong and Macau with respect to urban population density. On the other hand, the spreading of urban areas on farmlands causes new farmland reclamation and accelerated deforestation in the hilly surroundings. In addition, the displaced farmlands do not ensure food production because of both reclaiming farmlands on infertile lands and diversifying farming activities from grain production to market-oriented ones. The accelerated urbanization and farmland displacement are driven by profit-oriented development strategy and ineffective land use planning. Our findings demonstrate how spatial analysis can help to investigate the integrated effects of land policies on landscape.

Growth laws for delta crevasses in the Mississippi River Delta: observations and modeling

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Yocum, T. A.; Georgiou, I. Y.

2016-02-01

River deltas are accumulations of sedimentary deposits delivered by rivers via a network of distributary channels. Worldwide they are threatened by environmental changes, including subsidence, global sea level rise and a suite of other local factors. In the Mississippi River Delta (MRD) these impacts are exemplified, and have led to proposed solutions to build land that include sediment diversions, thereby reinitiating the delta cycle. While economically efficient, there are too few analogs of small deltas aside from laboratory studies, numerical modeling studies, theoretical approaches, and limited field driven observations. Anthropogenic crevasses in the modern delta are large enough to overcome limitations of laboratory deltas, and small enough to allow for "rapid" channel and wetland development, providing an ideal setting to investigate delta development mechanics. Crevasse metrics were obtained using a combination of geospatial tools, extracting key parameters (bifurcation length and width, channel order and depth) that were non-dimensionalized and compared to river-dominated delta networks previously studied. Analysis showed that most crevasses in the MRD appear to obey delta growth laws and delta allometry relationships, suggesting that crevasses do exhibit similar planform metrics to larger Deltas; the distance to mouth bar versus bifurcation order demonstrated to be a very reasonable first order estimate of delta-top footprint. However, some crevasses exhibited different growth metrics. To better understand the hydrodynamic and geomorphic controls governing crevasse evolution in the MRD, we assess delta dynamics via a suite of field observations and numerical modeling in both well-established and newly constructed crevasses. Our analysis suggests that delta development is affected by the relative influence of external (upstream and downstream) and internal controls on the hydrodynamic and sediment transport patterns in these systems.

Source areas and chemical composition of fine particulate matter in the Pearl River Delta region of China

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Hagler, G. S. W.; Bergin, M. H.; Salmon, L. G.; Yu, J. Z.; Wan, E. C. H.; Zheng, M.; Zeng, L. M.; Kiang, C. S.; Zhang, Y. H.; Lau, A. K. H.; Schauer, J. J.

Fine particulate matter (PM 2.5) was measured for 4 months during 2002-2003 at seven sites located in the rapidly developing Pearl River Delta region of China, an area encompassing the major cities of Hong Kong, Shenzhen and Guangzhou. The 4-month average fine particulate matter concentration ranged from 37 to 71 μg m -3 in Guangdong province and from 29 to 34 μg m -3 in Hong Kong. Main constituents of fine particulate mass were organic compounds (24-35% by mass) and sulfate (21-32%). With sampling sites strategically located to monitor the regional air shed patterns and urban areas, specific source-related fine particulate species (sulfate, organic mass, elemental carbon, potassium and lead) and daily surface winds were analyzed to estimate influential source locations. The impact of transport was investigated by categorizing 13 (of 20 total) sampling days by prevailing wind direction (southerly, northerly or low wind-speed mixed flow). The vicinity of Guangzhou is determined to be a major source area influencing regional concentrations of PM 2.5, with levels observed to increase by 18-34 μg m -3 (accounting for 46-56% of resulting particulate levels) at sites immediately downwind of Guangzhou. The area near Guangzhou is also observed to heavily impact downwind concentrations of lead. Potassium levels, related to biomass burning, appear to be controlled by sources in the northern part of the Pearl River Delta, near rural Conghua and urban Guangzhou. Guangzhou appears to contribute 5-6 μg m -3 of sulfate to downwind locations. Guangzhou also stands out as a significant regional source of organic mass (OM), adding 8.5-14.5 μg m -3 to downwind concentrations. Elemental carbon is observed to be strongly influenced by local sources, with highest levels found in urban regions. In addition, it appears that sources outside of the Pearl River Delta contribute a significant fraction of overall fine particulate matter in Hong Kong and Guangdong province. This is evident

From Natural to Design River Deltas

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Giosan, Liviu

2016-04-01

Productive and biologically diverse, deltaic lowlands attracted humans since prehistory and may have spurred the emergence of the first urban civilizations. Deltas continued to be an important nexus for economic development across the world and are currently home for over half a billion people. But recently, under the double whammy of sea level rise and inland sediment capture behind dams, they have become the most threatened coastal landscape. Here I will address several deceptively simple questions to sketch some unexpected answers using example deltas from across the world from the Arctic to the Tropics, from the Danube to the Indus, Mississippi to Godavari and Krishna, Mackenzie to Yukon. What is a river delta? What is natural and what is not in a river delta? Are the geological and human histories of a delta important for its current management? Is maintaining a delta the same to building a new one? Can we design better deltas than Nature? These answers help us see clearly that survival of deltas in the next century depends on human intervention and is neither assured nor simple to address or universally applicable. Empirical observations on the hydrology, geology, biology and biochemistry of deltas are significantly lagging behind modeling capabilities endangering the applicability of numerical-based reconstruction solutions and need to be ramped up significantly and rapidly across the world.

Connectivity in river deltas

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Passalacqua, P.; Hiatt, M. R.; Sendrowski, A.

2016-12-01

Deltas host approximately half a billion people and are rich in ecosystem diversity and economic resources. However, human-induced activities and climatic shifts are significantly impacting deltas around the world; anthropogenic disturbance, natural subsidence, and eustatic sea-level rise are major causes of threat to deltas and in many cases have compromised their safety and sustainability, putting at risk the people that live on them. In this presentation, I will introduce a framework called Delta Connectome for studying connectivity in river deltas based on different representations of a delta as a network. Here connectivity indicates both physical connectivity (how different portions of the system interact with each other) as well as conceptual (pathways of process coupling). I will explore several network representations and show how quantifying connectivity can advance our understanding of system functioning and can be used to inform coastal management and restoration. From connectivity considerations, the delta emerges as a leaky network that evolves over time and is characterized by continuous exchanges of fluxes of matter, energy, and information. I will discuss the implications of connectivity on delta functioning, land growth, and potential for nutrient removal.

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

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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.

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

Science.gov (United States)

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

Downstream hydraulic geometry of a tidally influenced river delta

NARCIS (Netherlands)

Sassi, M.G.; Hoitink, A.J.F.; Brye, de B.; Deleersnijder, E.

2012-01-01

Channel geometry in tidally influenced river deltas can show a mixed scaling behavior between that of river and tidal channel networks, as the channel forming discharge is both of river and tidal origin. We present a method of analysis to quantify the tidal signature on delta morphology, by

Tidal controls on river delta morphology

NARCIS (Netherlands)

Hoitink, A.J.F.; Wang, Z.B.; Vermeulen, B.; Huismans, Y.; Kästner, K.

2017-01-01

River delta degradation has been caused by extraction of natural resources, sediment retention by reservoirs, and sea-level rise. Despite global concerns about these issues, human activity in the world's largest deltas intensifies. Harbour development, construction of flood defences, sand mining and

Tidal controls on river delta morphology

NARCIS (Netherlands)

Hoitink, A.J.F.; Wang, Zhengbing; Vermeulen, B.; Huismans, Y; Kästner, K

River delta degradation has been caused by extraction of natural resources, sediment retention by reservoirs, and sea-level rise. Despite global concerns about these issues, human activity in the world’s largest deltas intensifies. Harbour development, construction of flood defences, sand mining and

Morphodynamics of a cyclic prograding delta: the Red River, Vietnam

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Maren, D.S. van

2004-01-01

River deltas are inhabited by over 60% of the world population, and are, consequently, of paramount agricultural and economical importance. They constitute unique wetland envi ronments which gives river deltas ecological importance as well. Additionally, many deltas contain large accumulations of

Influence of the characteristics of atmospheric boundary layer on the vertical distribution of air pollutant in China's Yangtze River Delta

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Wang, Chenggang; Cao, Le

2016-04-01

Air pollution occurring in the atmospheric boundary layer is a kind of weather phenomenon which decreases the visibility of the atmosphere and results in poor air quality. Recently, the occurrence of the heavy air pollution events has become more frequent all over Asia, especially in Mid-Eastern China. In December 2015, the most severe air pollution in recorded history of China occurred in the regions of Yangtze River Delta and Beijing-Tianjin-Hebei. More than 10 days of severe air pollution (Air Quality Index, AQI>200) appeared in many large cities of China such as Beijing, Tianjin, Shijiazhuang and Baoding. Thus, the research and the management of the air pollution has attracted most attentions in China. In order to investigate the formation, development and dissipation of the air pollutions in China, a field campaign has been conducted between January 1, 2015 and January 28, 2015 in Yangtze River Delta of China, aiming at a intensive observation of the vertical structure of the air pollutants in the atmospheric boundary layer during the time period with heavy pollution. In this study, the observation data obtained in the field campaign mentioned above is analyzed. The characteristics of the atmospheric boundary layer and the vertical distribution of air pollutants in the city Dongshan located in the center of Lake Taihu are shown and discussed in great detail. It is indicated that the stability of the boundary layer is the strongest during the nighttime and the early morning of Dongshan. Meanwhile, the major air pollutants, PM2.5 and PM10 in the boundary layer, reach their maximum values, 177.1μg m-3 and 285μg m-3 respectively. The convective boundary layer height in the observations ranges from approximately 700m to 1100m. It is found that the major air pollutants tend to be confined in a relatively shallow boundary layer, which represents that the boundary layer height is the dominant factor for controlling the vertical distribution of the air pollutants. In

Distribution and pollution, toxicity and risk assessment of heavy metals in sediments from urban and rural rivers of the Pearl River delta in southern China.

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Xiao, Rong; Bai, Junhong; Huang, Laibin; Zhang, Honggang; Cui, Baoshan; Liu, Xinhui

2013-12-01

Sediments were collected from the upper, middle and lower reaches of both urban and rural rivers in a typical urbanization zone of the Pearl River delta. Six heavy metals (Cd, Cr, Cu, Ni, Pb and Zn) were analyzed in all sediment samples, and their spatial distribution, pollution levels, toxicity and ecological risk levels were evaluated to compare the characteristics of heavy metal pollution between the two rivers. Our results indicated that the total contents of the six metals in all samples exceeded the soil background value in Guangdong province. Based on the soil quality thresholds of the China SEPA, Cd levels at all sites exceeded class III criteria, and other metals exhibited pollution levels exceeding class II or III criteria at both river sites. According to the sediment quality guidelines of the US EPA, all samples were moderately to heavily polluted by Cr, Cu, Ni, Pb and Zn. Compared to rural river sites, urban river sites exhibited heavier pollution. Almost all sediment samples from both rivers exhibited moderate to serious toxicity to the environment, with higher contributions from Cr and Ni. A "hot area" of heavy metal pollution being observed in the upper and middle reaches of the urban river area, whereas a "hot spot" was identified at a specific site in the middle reach of the rural river. Contrary metal distribution patterns were also observed along typical sediment profiles from urban and rural rivers. However, the potential ecological risk indices of rural river sediments in this study were equal to those of urban river sediments, implying that the ecological health issues of the rivers in the undeveloped rural area should also be addressed. Sediment organic matter and grain size might be important factors influencing the distribution profiles of these heavy metals.

Extraction and Analysis of Impervious Surfaces Based on a Spectral Un-Mixing Method Using Pearl River Delta of China Landsat TM/ETM+ Imagery from 1998 to 2008

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Renrong Chen

2012-02-01

Full Text Available Impervious surface area (ISA is considered as an indicator of environment change and is regarded as an important input parameter for hydrological cycle simulation, water management and area pollution assessment. The Pearl River Delta (PRD, the 3rd most important economic district of China, is chosen in this paper to extract the ISA information based on Landsat images of 1998, 2003 and 2008 by using a linear spectral un-mixing method and to monitor impervious surface change by analyzing the multi-temporal Landsat-derived fractional impervious surface. Results of this study were as follows: (1 the area of ISA in the PRD increased 79.09% from 1998 to 2003 and 26.88% from 2003 to 2008 separately; (2 the spatial distribution of ISA was described according to the 1998/2003 percentage respectively. Most of middle and high percentage ISA was located in northwestern and southeastern of the whole delta, and middle percentage ISA was mainly located in the city interior, high percentage ISA was mainly located in the suburban around the city accordingly; (3 the expanding direction and trend of high percentage ISA was discussed in order to understand the change of urban in this delta; High percentage ISA moved from inner city to edge of urban area during 1998–2003 and moved to the suburban area that far from the urban area mixed with jumpily and gradually during 2003–2008. According to the discussion of high percentage ISA spatial expanded direction, it could be found out that high percentage ISA moved outward from the centre line of Pearl River of the whole delta while a high ISA percentage in both shores of the Pearl River Estuary moved toward the Pearl River; (4 combining the change of ISA with social conditions, the driving relationship was analyzed in detail. It was evident that ISA percentage change had a deep relationship with the economic development of this region in the past ten years. Contemporaneous major sport events (16th Asia Games of

An Object-Based Classification Approach for Mapping Migrant Housing in the Mega-Urban Area of the Pearl River Delta (China

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Sebastian D’Oleire-Oltmanns

2011-08-01

Full Text Available Urban areas develop on formal and informal levels. Informal development is often highly dynamic, leading to a lag of spatial information about urban structure types. In this work, an object-based remote sensing approach will be presented to map the migrant housing urban structure type in the Pearl River Delta, China. SPOT5 data were utilized for the classification (auxiliary data, particularly up-to-date cadastral data, were not available. A hierarchically structured classification process was used to create (spectral independence from single satellite scenes and to arrive at a transferrable classification process. Using the presented classification approach, an overall classification accuracy of migrant housing of 68.0% is attained.

Urbanization signatures in strong versus weak precipitation over the Pearl River Delta metropolitan regions of China

International Nuclear Information System (INIS)

Li Weibiao; Chen Sheng; Wen Zhiping; Wang Baomin; Chen Guixing; Sha Weimin; Luo Cong; Feng Yerong

2011-01-01

We assess the issues of urban effects on the precipitation over the Pearl River Delta (PRD) metropolitan regions of China. The spatial and temporal variations of strong versus weak precipitation over the PRD and surrounding nonurban areas are investigated. The results show that the urbanization signatures in strong precipitation are significantly different from those in weak precipitation over the urban areas. The PRD experiences more strong precipitation but less weak precipitation compared to surrounding nonurban regions. In addition, the strong precipitation over the PRD displays a pronounced seasonal variation. The seasonality of weak precipitation, however, is much weaker over the PRD compared to the surrounding nonurban regions. Moreover, a strengthening in the precipitation intensity, a reduction in the rainfall frequency and an increase in the convective precipitation as well as the afternoon precipitation are found over the urban areas, which are probably associated with the abundance in strong precipitation and the deficit in weak precipitation over the PRD.

Identifying hotspots and management of critical ecosystem services in rapidly urbanizing Yangtze River Delta Region, China.

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Cai, Wenbo; Gibbs, David; Zhang, Lang; Ferrier, Graham; Cai, Yongli

2017-04-15

Rapid urbanization has altered many ecosystems, causing a decline in many ecosystem services, generating serious ecological crisis. To cope with these challenges, we presented a comprehensive framework comprising five core steps for identifying and managing hotspots of critical ecosystem services in a rapid urbanizing region. This framework was applied in the case study of the Yangtze River Delta (YRD) Region. The study showed that there was large spatial heterogeneity in the hotspots of ecosystem services in the region, hotspots of supporting services and regulating services aggregately distributing in the southwest mountainous areas while hotspots of provisioning services mainly in the northeast plain, and hotspots of cultural services widespread in the waterbodies and southwest mountainous areas. The regionalization of the critical ecosystem services was made through the hotspot analysis. This study provided valuable information for environmental planning and management in a rapid urbanizing region and helped improve China's ecological redlines policy at regional scale. Copyright © 2017 Elsevier Ltd. All rights reserved.

Corporate social capital, market orientation, organizational learning and service innovation performance: An empirical survey in the Pearl river delta of China

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Zhaoquan Jian

2015-04-01

Full Text Available Purpose: Service innovation performance (SIP is an important driver of growth and wealth of service firms in wide range of industries. Yet, few research studies have been done to explore the influencing factors. The purpose of this study intends to identify the impacts of corporate social capital, market orientation and organizational learning on service innovation in the Pearl River Delta of China.Design/methodology/approach: The paper mainly adopted the empirical research. A Structure Equation Model containing an intermediary variable was established to explore the relationships of SIP.Findings and Originality/value: The main findings of the research support some of the propositions: (1 Both corporate social capital, market orientation and organizational learning have distinct positive impact on service innovation performance; (2 Corporate social capital, market orientation has a positive effect on organizational learning respectively, and (3 organizational learning plays a mediating role between the corporate social capital, market orientation and service innovation performance.Research limitations/implications: The research object of this paper has been restricted to the enterprises in Pearl River Delta of China. By contrast, variables and theories all come from western research, which was not adequate in explaining some results in the context of China. Given the limited theoretical and empirical research to service innovation, future research studies might widen their examinations to include other potential factors.Practical implications: This study has significant implications to enterprises. The results of this study suggest that enterprises should establish the social networks accommodated by the development of organization. In addition, more attention should be paid to focus on market orientation to enhance the ability to respond to changes in the market environment. It’s particularly necessary to strengthen organizational learning to

Sources and characteristics of carbonaceous aerosol in two largest cities in Pearl River Delta Region, China

Science.gov (United States)

Duan, Jingchun; Tan, Jihua; Cheng, Dingxi; Bi, Xinhui; Deng, Wenjing; Sheng, Guoying; Fu, Jiamo; Wong, M. H.

PM 2.5 samples were collected at five sites in Guangzhou and Hong Kong, Pearl River Delta Region (PRDR), China in both summer and winter during 2004-2005. Elemental carbon (EC) and organic carbon (OC) in these samples were measured. The OC and EC concentrations ranked in the order of urban Guangzhou > urban Hong Kong > background Hong Kong. Total carbonaceous aerosol (TCA) contributed less to PM 2.5 in urban Guangzhou (32-35%) than that in urban Hong Kong (43-57%). The reason may be that, as an major industrial city in South China, Guangzhou would receive large amount of inorganic aerosol from all kinds of industries, however, as a trade center and seaport, urban Hong Kong would mainly receive organic aerosol and EC from container vessels and heavy-duty diesel trucks. At Hong Kong background site Hok Tsui, relatively lower contribution of TCA to PM 2.5 may result from contributions of marine inorganic aerosol and inland China pollutant. Strong correlation ( R2=0.76-0.83) between OC and EC indicates minor fluctuation of emission and the secondary organic aerosol (SOA) formation in urban Guangzhou. Weak correlation between OC and EC in Hong Kong can be related to the impact of the long-range transported aerosol from inland China. Averagely, secondary OC (SOC) concentrations were 3.8-5.9 and 10.2-12.8 μg m -3, respectively, accounting for 21-32% and 36-42% of OC in summer and winter in Guangzhou. The average values of 4.2-6.8% for SOA/ PM 2.5 indicate that SOA was minor component in PM 2.5 in Guangzhou.

Remote Sensing of River Delta Inundation: Exploiting the Potential of Coarse Spatial Resolution, Temporally-Dense MODIS Time Series

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Claudia Kuenzer

2015-07-01

Full Text Available River deltas belong to the most densely settled places on earth. Although they only account for 5% of the global land surface, over 550 million people live in deltas. These preferred livelihood locations, which feature flat terrain, fertile alluvial soils, access to fluvial and marine resources, a rich wetland biodiversity and other advantages are, however, threatened by numerous internal and external processes. Socio-economic development, urbanization, climate change induced sea level rise, as well as flood pulse changes due to upstream water diversion all lead to changes in these highly dynamic systems. A thorough understanding of a river delta’s general setting and intra-annual as well as long-term dynamic is therefore crucial for an informed management of natural resources. Here, remote sensing can play a key role in analyzing and monitoring these vast areas at a global scale. The goal of this study is to demonstrate the potential of intra-annual time series analyses at dense temporal, but coarse spatial resolution for inundation characterization in five river deltas located in four different countries. Based on 250 m MODIS reflectance data we analyze inundation dynamics in four densely populated Asian river deltas—namely the Yellow River Delta (China, the Mekong Delta (Vietnam, the Irrawaddy Delta (Myanmar, and the Ganges-Brahmaputra (Bangladesh, India—as well as one very contrasting delta: the nearly uninhabited polar Mackenzie Delta Region in northwestern Canada for the complete time span of one year (2013. A complex processing chain of water surface derivation on a daily basis allows the generation of intra-annual time series, which indicate inundation duration in each of the deltas. Our analyses depict distinct inundation patterns within each of the deltas, which can be attributed to processes such as overland flooding, irrigation agriculture, aquaculture, or snowmelt and thermokarst processes. Clear differences between mid

The Effect of Urban Heat Island on Climate Warming in the Yangtze River Delta Urban Agglomeration in China

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Qunfang Huang

2015-07-01

Full Text Available The Yangtze River Delta (YRD has experienced rapid urbanization and dramatic economic development since 1978 and the Yangtze River Delta urban agglomeration (YRDUA has been one of the three largest urban agglomerations in China. We present evidence of a significant urban heat island (UHI effect on climate warming based on an analysis of the impacts of the urbanization rate, urban population, and land use changes on the warming rate of the daily average, minimal (nighttime and maximal (daytime air temperature in the YRDUA using 41 meteorological stations observation data. The effect of the UHI on climate warming shows a large spatial variability. The average warming rates of average air temperature of huge cities, megalopolises, large cities, medium-sized cities, and small cities are 0.483, 0.314 ± 0.030, 0.282 ± 0.042, 0.225 ± 0.044 and 0.179 ± 0.046 °C/decade during the period of 1957–2013, respectively. The average warming rates of huge cities and megalopolises are significantly higher than those of medium-sized cities and small cities, indicating that the UHI has a significant effect on climate warming (t-test, p < 0.05. Significantly positive correlations are found between the urbanization rate, population, built-up area and warming rate of average air temperature (p < 0.001. The average warming rate of average air temperature attributable to urbanization is 0.124 ± 0.074 °C/decade in the YRDUA. Urbanization has a measurable effect on the observed climate warming in the YRD aggravating the global climate warming.

Source apportionment and health effect of NO_x over the Pearl River Delta region in southern China

International Nuclear Information System (INIS)

Lu, Xingcheng; Yao, Teng; Li, Ying; Fung, Jimmy C.H.; Lau, Alexis K.H.

2016-01-01

As one of the most notorious atmospheric pollutants, NO_x not only promotes the formation of ozone but also has adverse health effects on humans. It is therefore of great importance to study the sources of NO_x and its effects on human health. The Comprehensive Air Quality Model (CAMx) modeling system and ozone source apportionment technology (OSAT) were used to study the contribution of NO_x from different emission sources over southern China. The results indicate that heavy duty diesel vehicles (HDDVs) and industrial point sources are the two major local NO_x sources, accounting for 30.8% and 18.5% of local NO_x sources, respectively. In Hong Kong, marine emissions contributed around 43.4% of local NO_x in 2011. Regional transport is another important source of this pollutant, especially in February and November, and it can contribute over 30% of ambient NO_x on average. Power plant point emission is an significant regional source in Zhuhai, Zhongshan and Foshan. The total emission sources are estimated to cause 2119 (0–4405) respiratory deaths and 991 (0–2281) lung cancer deaths due to long-term exposure to NO_x in the Pearl River Delta region. Our results suggest that local governments should combine their efforts and vigorously promote further reduction of NO_x emissions, especially for those sources that make a substantial contribution to NO_x emissions and affect human health: HDDV, LDGV, industrial point sources and marine sources. - Highlights: • WRF-CAMx modeling system with OSAT was used to study the source of NO_x over Pearl River Delta region in China. • The results indicated that local emission and regional transportation are important contributors for NO_x in this region. • Heavy duty diesel vehicle, marine emission and industrial point source are three important contribution sectors. • Long-term exposure to NO_x is estimated to cause 2119 respiratory deaths and 991 lung cancer deaths in PRD during 2011. - Result indicated that heavy duty

Volatile Organic Compound (VOC) measurements in the Pearl River Delta (PRD) region, China

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Liu, Ying; Shao, Min; Lu, Sihua; Chang, Chih-Chung; Wang, Jia-Lin; Chen, Gao

2008-03-01

We measured levels of ambient volatile organic compounds (VOCs) at seven sites in the Pearl River Delta (PRD) region of China during the Air Quality Monitoring Campaign spanning 4 October to 3 November 2004. Two of the sites, Guangzhou (GZ) and Xinken (XK), were intensive sites at which we collected multiple daily canister samples. The observations reported here provide a look at the VOC distribution, speciation, and photochemical implications in the PRD region. Alkanes constituted the largest percentage (>40%) in mixing ratios of the quantified VOCs at six sites; the exception was one major industrial site that was dominated by aromatics (about 52%). Highly elevated VOC levels occurred at GZ during two pollution episodes; however, the chemical composition of VOCs did not exhibit noticeable changes during these episodes. We calculated the OH loss rate to estimate the chemical reactivity of all VOCs. Of the anthropogenic VOCs, alkenes played a predominant role in VOC reactivity at GZ, whereas the contributions of reactive aromatics were more important at XK. Our preliminary analysis of the VOC correlations suggests that the ambient VOCs at GZ came directly from local sources (i.e., automobiles); those at XK were influenced by both local emissions and transportation of air mass from upwind areas.

Volatile Organic Compound (VOC measurements in the Pearl River Delta (PRD region, China

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Chih-chung Chang

2008-03-01

Full Text Available We measured levels of ambient volatile organic compounds (VOCs at seven sites in the Pearl River Delta (PRD region of China during the Air Quality Monitoring Campaign spanning 4 October to 3 November 2004. Two of the sites, Guangzhou (GZ and Xinken (XK, were intensive sites at which we collected multiple daily canister samples. The observations reported here provide a look at the VOC distribution, speciation, and photochemical implications in the PRD region. Alkanes constituted the largest percentage (>40% in mixing ratios of the quantified VOCs at six sites; the exception was one major industrial site that was dominated by aromatics (about 52%. Highly elevated VOC levels occurred at GZ during two pollution episodes; however, the chemical composition of VOCs did not exhibit noticeable changes during these episodes. We calculated the OH loss rate to estimate the chemical reactivity of all VOCs. Of the anthropogenic VOCs, alkenes played a predominant role in VOC reactivity at GZ, whereas the contributions of reactive aromatics were more important at XK. Our preliminary analysis of the VOC correlations suggests that the ambient VOCs at GZ came directly from local sources (i.e., automobiles; those at XK were influenced by both local emissions and transportation of air mass from upwind areas.

Regional contribution to PM1 pollution during winter haze in Yangtze River Delta, China.

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Tang, Lili; Yu, Hongxia; Ding, Aijun; Zhang, Yunjiang; Qin, Wei; Wang, Zhuang; Chen, Wentai; Hua, Yan; Yang, Xiaoxiao

2016-01-15

To quantify regional sources contributing to submicron particulate matter (PM1) pollution in haze episodes, on-line measurements combining two modeling methods, namely, positive matrix factorization (PMF) and backward Lagrangian particle dispersion modeling (LPDM), were conducted for the period of one month in urban Nanjing, a city located in the western part of Yangtze River Delta (YRD) region of China. Several multi-day haze episodes were observed in December 2013. Long-range transport of biomass burning from the southwestern YRD region largely contributed to PM1 pollution with more than 25% of total organics mass in a lasting heavy haze. The LPDM analysis indicates that regional transport is a main source contributing to secondary low-volatility production. The high-potential source regions of secondary low-volatility production are mainly located in areas to the northeast of the city. High aerosol pollution was mainly contributed by regional transport associated with northeastern air masses. Such regional transport on average accounts for 46% of total NR-PM1 with sulfate and aged low-volatility organics being the largest fractions (>65%). Copyright © 2015 Elsevier B.V. All rights reserved.

Coordinated Development between Urban Tourism Economy and Transport in the Pearl River Delta, China

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Qiuxia Zheng

2016-12-01

Full Text Available By selecting the panel data from 2005 to 2014 of 9 cities in the Pearl River Delta (PRD in China, this paper respectively establishes the evaluation index system of tourism economy and transport. It also applies a synthetic evaluation model and coupling coordination model to estimate comprehensive indices of tourism economy and transport system and their coordinated relationships. The results show that: (1 during 2005–2014, the synthetic indices of tourism economy generally presented constantly upward tendency and the synthetic indices of transport represented wave-like raising trend in the PRD region; (2 during 2005–2014, the 9 cities in the PRD region gradually tended to have coordinated development between tourism economy and transport, and the central area of the PRD region developed faster than the flanks; (3 the correlations between the tourism economy and transport of the cities with abundant tourism resources, developed economy, and advanced transport facilities were more remarkable, and the coordination degrees were higher. Besides, macro-policies, mega-events, and locations also impacted on coordinated development between the tourism economy and transport in the PRD region.

Distribution and Source Apportionment of Polycyclic Aromatic Hydrocarbons (PAHs) in Forest Soils from Urban to Rural Areas in the Pearl River Delta of Southern China

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Xiao, Yihua; Tong, Fuchun; Kuang, Yuanwen; Chen, Bufeng

2014-01-01

The upper layer of forest soils (0–20 cm depth) were collected from urban, suburban, and rural areas in the Pearl River Delta of Southern China to estimate the distribution and the possible sources of polycyclic aromatic hydrocarbons (PAHs). Total concentrations of PAHs in the forest soils decreased significantly along the urban–suburban–rural gradient, indicating the influence of anthropogenic emissions on the PAH distribution in forest soils. High and low molecular weight PAHs dominated in the urban and rural forest soils, respectively, implying the difference in emission sources between the areas. The values of PAH isomeric diagnostic ratios indicated that forest soil PAHs were mainly originated from traffic emissions, mixed sources and coal/wood combustion in the urban, suburban and rural areas, respectively. Principal component analysis revealed that traffic emissions, coal burning and residential biomass combustion were the three primary contributors to forest soil PAHs in the Pearl River Delta. Long range transportation of PAHs via atmosphere from urban area might also impact the PAHs distribution in the forest soils of rural area. PMID:24599040

Contamination characteristics and source apportionment of methylated PAHs in agricultural soils from Yangtze River Delta, China

International Nuclear Information System (INIS)

Chen, Weixiao; Wu, Xinyi; Zhang, Haiyun; Sun, Jianteng; Liu, Wenxin; Zhu, Lizhong; Li, Xiangdong; Tsang, Daniel C.W.; Tao, Shu; Wang, Xilong

2017-01-01

Alkylated PAHs (APAHs) have been shown to be more toxic and persistent than their non-alkylated parent compounds. However, little is known about the extent of soil contamination by these pollutants. To help understand agricultural soil pollution by these compounds at a regional scale, a total of 18 methylated PAHs (MPAHs, a major class of APAHs) in 243 soil samples were analyzed. These soil samples were collected from 11 sites in the Yangtze River Delta (YRD) region, a representative fast developing area in China. The total concentration of MPAHs (∑18MPAHs) ranged from 5.5 to 696.2 ng/g dry soil, with methylnaphthalenes (M-NAPs) and methylphenanthrenes (M-PHEs) accounting for more than 70% of the compositional profile. Relatively high concentrations of ∑18MPAHs were found in Jiaxing and Huzhou areas of Zhejiang province, as well as on the border between the cities of Wuxi and Suzhou. Different MPAH groups showed dissimilar spatial distribution patterns. The spatial distribution of lower molecular weight MPAHs was related to agricultural straw burning and emissions/depositions from industrial activities, whereas that of higher molecular weight MPAHs was much more a function of the total organic carbon (TOC) content of soil. Although coal, biomass (crop straw and wood), and petroleum combustion were identified to be the major emission sources for most of the sampling sites, the areas with relatively severe pollution with ∑18MPAHs resulted from the localized hotspots of petroleum leakage. Isomeric MPAHs with methyl group substituted at 2- (β) position exhibited significantly higher concentrations than those substituted at 1- (α) position. Results of this work help to understand soil pollution by MPAHs, and are useful for designing effective strategies for pollution control so as to ensure food safety in areas with fast economic growth. - Highlights: • Several 2–4 rings methyl-PAHs were investigated in soils from Yangtze River Delta. • Higher levels of �

Heavy metal pollution in surface soils of Pearl River Delta, China.

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Jinmei, Bai; Xueping, Liu

2014-12-01

Heavy metal pollution is an increasing environmental problem in Chinese regions undergoing rapid economic and industrial development, such as the Pearl River Delta (PRD), southern China. We determined heavy metal concentrations in surface soils from the PRD. The soils were polluted with heavy metals, as defined by the Chinese soil quality standard grade II criteria. The degree of pollution decreased in the order Cd > Cu > Ni > Zn > As > Cr > Hg > Pb. The degree of heavy metal pollution by land use decreased in the order waste treatment plants (WP) > urban land (UL) > manufacturing industries (MI) > agricultural land (AL) > woodland (WL) > water sources (WS). Pollution with some of the metals, including Cd, Cu, Ni, and Zn, was attributed to the recent rapid development of the electronics and electroplating industries. Cd, Hg, and Pb (especially Cd) pose high potential ecological risks in all of the zones studied. The soils posing significantly high and high potential ecological risks from Cd covered 73.3 % of UL, 50 % of MI and WP land, and 48.5 % of AL. The potential ecological risks from heavy metals by land use decreased in the order UL > MI > AL > WP > WL > WS. The control of Cd, Hg, and Pb should be prioritized in the PRD, and emissions in wastewater, residue, and gas discharges from the electronics and electroplating industry should be decreased urgently. The use of chemical fertilizers and pesticides should also be decreased.

Variability of ozone depleting substances as an indication of emissions in the Pearl River Delta, China

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Chang, Chih-Chung; Lai, Cheng-Hsun; Wang, Chieh-Heng; Liu, Ying; Shao, Min; Zhang, Yuanhang; Wang, Jia-Lin

The continued production and consumption of five major chlorocarbons, i.e., CFC-11 (CCl 3F), CFC-12 (CCl 2F 2), CFC-113 (CCl 2FCClF 2), CH 3CCl 3, and CCl 4, as allowed by developing nations including China under the Montreal Protocol, were assessed by a method employing concentration variability. Measurements of the five ozone depleting substances (ODS) were measured in downtown Guangzhou and a rural site in the Pearl River Delta (PRD), China by both in situ and flask measurements. In order to post a contrast to PRD with a referencing environment of minimal emissions, in situ measurements were also conducted in Taipei, Taiwan, where a decade long phase-out of CFCs has been implemented. In general, the variability of chlorocarbons in the PRD sites was significantly greater than that of Taipei. While the abundance of the five ODSs in Taipei was relatively uniform with a relative standard deviation (RSD) varying between 3% and 16%, their variability in PRD with the exception of CFC-113 was significantly more pronounced, clearly indicating the significant usage of ODSs. The variability of CFC-113 in both cities, however, was nearly indiscernible from the instrumental precision, suggesting little usage of CFC-113 in China. Methyl chloroform in Guangzhou exhibited a strong link to solvent evaporation as it showed a tight correlation with ambient toluene. Alarmingly, CCl 4 was the most variable of the five major chlorocarbons in Guangzhou, which should arouse a serious concern for public health due to its carcinogenicity.

Experimental river delta size set by multiple floods and backwater hydrodynamics.

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Ganti, Vamsi; Chadwick, Austin J; Hassenruck-Gudipati, Hima J; Fuller, Brian M; Lamb, Michael P

2016-05-01

River deltas worldwide are currently under threat of drowning and destruction by sea-level rise, subsidence, and oceanic storms, highlighting the need to quantify their growth processes. Deltas are built through construction of sediment lobes, and emerging theories suggest that the size of delta lobes scales with backwater hydrodynamics, but these ideas are difficult to test on natural deltas that evolve slowly. We show results of the first laboratory delta built through successive deposition of lobes that maintain a constant size. We show that the characteristic size of delta lobes emerges because of a preferential avulsion node-the location where the river course periodically and abruptly shifts-that remains fixed spatially relative to the prograding shoreline. The preferential avulsion node in our experiments is a consequence of multiple river floods and Froude-subcritical flows that produce persistent nonuniform flows and a peak in net channel deposition within the backwater zone of the coastal river. In contrast, experimental deltas without multiple floods produce flows with uniform velocities and delta lobes that lack a characteristic size. Results have broad applications to sustainable management of deltas and for decoding their stratigraphic record on Earth and Mars.

Mixing state of oxalic acid containing particles in the rural area of Pearl River Delta, China: implication for seasonal formation mechanism of Secondary Organic Aerosol (SOA)

OpenAIRE

Cheng, Chunlei; Li, Mei; Chan, Chak K.; Tong, Haijie; Chen, Changhong; Chen, Duohong; Wu, Dui; Li, Lei; Cheng, Peng; Gao, Wei; Huang, Zhengxu; Li, Xue; Fu, Zhong; Bi, Yanru; Zhou, Zhen

2016-01-01

The formation of oxalic acid and its mixing state in atmospheric particulate matter (PM) were studied using a single particle aerosol mass spectrometer (SPAMS) in the summer and winter of 2014 in Heshan, a supersite in the rural area of the Pearl River Delta (PRD) region in China. Oxalic acid-containing particles accounted for 2.5 % and 2.7 % in total detected ambient particles in summer and winter, respectively. Oxalic acid was measured in particles classified as elemental carb...

Long-term trend of haze pollution and impact of particulate matter in the Yangtze River Delta, China

International Nuclear Information System (INIS)

Cheng, Zhen; Wang, Shuxiao; Jiang, Jingkun; Fu, Qingyan; Chen, Changhong; Xu, Bingye; Yu, Jianqiao; Fu, Xiao; Hao, Jiming

2013-01-01

Haze pollution caused by heavy particulate matter (PM) loading brings significant damage in eastern China. Long-term monitoring from 1980 to 2011 and 1-year field measurement in 2011–2012 are used for investigating visibility variation and the impact of PM pollution for the Yangtze River Delta (YRD). It was found that visual range in the YRD endured a sharp reduction from 13.2 km to 10.5 km during 1980–2000. Average mass extinction efficiency (MEE) for inhalable PM (PM 10 ) is 2.25 m 2 /g in 2001–2011, and extinction coefficient due to PM 10 is 207 Mm −1 , accounting for 36.2% of total extinction coefficient. MEE of PM 2.5 and PM 2.5–10 are 4.08 m 2 /g and 0.58 m 2 /g, respectively. Extinction coefficient due to PM 2.5 and PM 2.5–10 is 198 Mm −1 (39.6%) and 20 Mm −1 (4.0%) in 2011–2012. Maximum daily concentration of PM 10 and PM 2.5 is estimated to be 63 μg/m 3 (RH: 73%) and 38 μg/m 3 (RH: 70%) to keep visual range above 10 km. Fine particulate matter is the key factor for haze pollution improvement in the YRD area. -- Highlights: •Long-term visual range variation and its causes in the Yangtze River Delta are analyzed. •Quantitative contribution of particulate matter to haze pollution is estimated. •Mass extinction efficiency of PM 10 , PM 2.5 , and PM 2.5–10 is estimated. -- The long-term variation of haze pollution in the YRD and its cause is investigated and the quantitative contribution of particulate matter to haze pollution is estimated

Sustainable Urban Development and Land Use Change—A Case Study of the Yangtze River Delta in China

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Haiyan Zhang

2011-07-01

Full Text Available This paper introduces a sustainability assessment method for the rapidly urbanizing Yangtze River Delta in China addressing the role of land use pattern. We first calculated the sustainability component scores of 16 cities in the area in 2000 and 2005. The results showed that socioeconomic and environmental conditions improved while the performance of resource-use degraded from 2000 to 2005. We then made a spatial analysis of land use change (LUC using geographic information systems during 1990–2000. We found that diverse spatiotemporal transformation occurred among the cities and identified urban development cluster patterns and profiles based on development density. Finally, we examined the impact of LUC on sustainable urban development (SUD. Using regression techniques, we demonstrated that urbanization, infrastructure development, industrial structure and income significantly affected environmental performance and resource-use. These results suggest a moderate pace of LUC with steady economic growth being key to SUD.

Effects of elevated O3 concentration on winter wheat and rice yields in the Yangtze River Delta, China

International Nuclear Information System (INIS)

Wang Xiaoke; Zhang Qianqian; Zheng Feixiang; Zheng Qiwei; Yao Fangfang; Chen Zhan; Zhang Weiwei; Hou Peiqiang; Feng Zhaozhong; Song Wenzhi; Feng Zongwei; Lu Fei

2012-01-01

The effects of a continuing rise of ambient ozone on crop yield will seriously threaten food security in China. In the Yangtze River Delta, a rapidly developing and seriously air polluted region in China, innovative open-top chambers have been established to fumigate winter wheat and rice in situ with elevated O 3 . Five years of study have shown that the yields of wheat and rice decreased with increasing O 3 concentration. There were significant relationships between the relative yield and AOT40 (accumulated hourly O 3 concentration over 40 ppb) for both winter wheat and rice. Winter wheat was more sensitive to O 3 than rice. O 3 -induced yield declines were attributed primarily to 1000-grain weight and harvest index for winter wheat, and attributed primarily to grain number per panicle and harvest index for rice. Control of ambient O 3 pollution and breeding of O 3 tolerant crops are urgent to guarantee food security in China. - Highlights: ► The wheat and rice response to ozone had been investigated for five years in China. ► There were significant relationships between relative crop yields and AOT40 dose. ► O 3 -induced wheat yield loss was primarily due to 1000-grain weight and harvest index. ► O 3 -induced rice yield loss was primarily due to grains per panicle and harvest index. ► Wheat and rice in this study are more sensitive to O 3 than previous investigations. - The dose–response relationships derived from field fumigation experiments over 5 years can be used to accurately estimate crop losses in China.

Top-down estimates of benzene and toluene emissions in the Pearl River Delta and Hong Kong, China

Science.gov (United States)

Fang, Xuekun; Shao, Min; Stohl, Andreas; Zhang, Qiang; Zheng, Junyu; Guo, Hai; Wang, Chen; Wang, Ming; Ou, Jiamin; Thompson, Rona L.; Prinn, Ronald G.

2016-03-01

Benzene (C6H6) and toluene (C7H8) are toxic to humans and the environment. They are also important precursors of ground-level ozone and secondary organic aerosols and contribute substantially to severe air pollution in urban areas in China. Discrepancies exist between different bottom-up inventories for benzene and toluene emissions in the Pearl River Delta (PRD) and Hong Kong (HK), which are emission hot spots in China. This study provides top-down estimates of benzene and toluene emissions in the PRD and HK using atmospheric measurement data from a rural site in the area, Heshan, an atmospheric transport model, and an inverse modeling method. The model simulations captured the measured mixing ratios during most pollution episodes. For the PRD and HK, the benzene emissions estimated in this study for 2010 were 44 (12-75) and 5 (2-7) Gg yr-1 for the PRD and HK, respectively, and the toluene emissions were 131 (44-218) and 6 (2-9) Gg yr-1, respectively. Temporal and spatial differences between the inversion estimate and four different bottom-up emission estimates are discussed, and it is proposed that more observations at different sites are urgently needed to better constrain benzene and toluene (and other air pollutant) emissions in the PRD and HK in the future.

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

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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.

Cohesive Sedimentary Processes on River-Dominated Deltas: New Perspectives from the Mississippi River Delta Front, Gulf of Mexico

Science.gov (United States)

Bentley, S. J.; Keller, G. P.; Obelcz, J.; Maloney, J. M.; Xu, K.; Georgiou, I. Y.; Miner, M. D.

2016-12-01

On river deltas dominated by proximal sediment accumulation (Mississippi, Huang He, others), the delta front region is commonly dominated by rapid accumulation of cohesive fluvial sediments, and mass-wasting processes that remobilize recently deposited sediments. Mass transport is preconditioned in sediments by high water content, biogenic gas production, over steepening, and is commonly triggered by strong wave loading and other processes. This understanding is based on extensive field studies in the 1970's and 80's. Recent studies of the Mississippi River Delta Front are yielding new perspectives on these processes, in a time of anthropogenically reduced sediment loads, rising sea level, and catastrophic deltaic land loss. We have synthesized many industry data sets collected since ca. 1980, and conducted new pilot field and modeling studies of sedimentary and morphodynamic processes. These efforts have yielded several key findings that diverge from historical understanding of this dynamic setting. First, delta distributary mouths have ceased seaward progradation, ending patterns that have been documented since the 18th century. Second, despite reduced sediment supply, offshore mass transport continues, yielding vertical displacements at rates of 1 m/y. This displacement is apparently forced by wave loading from storm events of near-annual return period, rather than major hurricanes that have been the focus of most previous studies. Third, core analysis indicates that this vertical displacement is occurring along failure planes >3 m in the seabed, rather than in more recently deposited sediments closer to the sediment-water interface. These seabed morphodynamics have the potential to destabilize both nearshore navigation infrastructure, and seabed hydrocarbon infrastructure offshore. As well, these findings raise more questions regarding the future seabed evolution offshore of major river deltas, in response to anthropogenic and climatic forcing.

Distribution, historical trends and inventories of polychlorinated biphenyls in sediments from Yangtze River Estuary and adjacent East China Sea

International Nuclear Information System (INIS)

Yang Huayun; Zhuo Shanshan; Xue Bin; Zhang Chunlong; Liu Weiping

2012-01-01

A large portion of polychlorinated biphenyls (PCBs) from e-waste released into the coastal areas may be the potential source of PCBs to the global oceans. The paper presents data of PCBs concentrations in fifty surface sediment samples and a dated sediment core in Yangtze River Delta (YRE) and adjacent East China Sea (ECS). The total PCBs levels varied from 5.08 to 19.64 ng/g dry weight, with the highest concentrations situate within the river-sea boundary zone which is so-called “marginal filter”. Concurrent with the operation of e-waste recycling over the last two decades, PCB fluxes started to rise again after 1980s and reached a maximum in this century. The full data set was used to estimate the burden of PCBs in YRE and adjacent ECS. A total sediment burdens were 192.8 tons, with the spatial density of 364 ng/cm 2 which accounts for 1.9% of all the PCBs in China. - Highlights: ► PCBs residues remained widespread in Yangtze River Delta and adjacent East China Sea. ► Highest PCBs concentrations situate within the river-sea boundary zone. ► Congener profiles and PCA highlight the influence of e-waste recycling. ► Temporal distributions indicated PCB fluxes reached a maximum in this century. ► Total sediment burdens accounts for 1.9 % of all the PCBs in China. - Spatial and temporal distributions of polychlorinated biphenyls have been delineated in sediments from Yangtze River Estuary and adjacent East China Sea.

River salinity on a mega-delta, an unstructured grid model approach.

Science.gov (United States)

Bricheno, Lucy; Saiful Islam, Akm; Wolf, Judith

2014-05-01

With an average freshwater discharge of around 40,000 m3/s the BGM (Brahmaputra Ganges and Meghna) river system has the third largest discharge worldwide. The BGM river delta is a low-lying fertile area covering over 100,000 km2 mainly in India and Bangladesh. Approximately two-thirds of the Bangladesh people work in agriculture and these local livelihoods depend on freshwater sources directly linked to river salinity. The finite volume coastal ocean model (FVCOM) has been applied to the BGM delta in order to simulate river salinity under present and future climate conditions. Forced by a combination of regional climate model predictions, and a basin-wide river catchment model, the 3D baroclinic delta model can determine river salinity under the current climate, and make predictions for future wet and dry years. The river salinity demonstrates a strong seasonal and tidal cycle, making it important for the model to be able to capture a wide range of timescales. The unstructured mesh approach used in FVCOM is required to properly represent the delta's structure; a complex network of interconnected river channels. The model extends 250 km inland in order to capture the full extent of the tidal influence and grid resolutions of 10s of metres are required to represent narrow inland river channels. The use of FVCOM to simulate flows so far inland is a novel challenge, which also requires knowledge of the shape and cross-section of the river channels.

Spatial and temporal characteristics of warm season convection over Pearl River Delta region, China, based on 3 years of operational radar data

Science.gov (United States)

Chen, Xingchao; Zhao, Kun; Xue, Ming

2014-11-01

This study examines the temporal and spatial characteristics and distributions of convection over the Pearl River Delta region of Guangzhou, China, during the May-September warm season, using, for the first time for such a purpose, 3 years of operational Doppler radar data in the region. Results show that convective features occur most frequently along the southern coast and the windward slope of the eastern mountainous area of Pearl River Delta, with the highest frequency occurring in June and the lowest in September among the 5 months. The spatial frequency distribution pattern also roughly matches the accumulated precipitation pattern. The occurrence of convection in this region also exhibits strong diurnal cycles. During May and June, the diurnal distribution is bimodal, with the maximum frequency occurring in the early afternoon and a secondary peak occurring between midnight and early morning. The secondary peak is much weaker in July, August, and September. Convection near the coast is found to occur preferentially on days when a southerly low-level jet (LLJ) exists, especially during the Meiyu season. Warm, moist, and unstable air is transported from the ocean to land by LLJs on these days, and the lifting along the coast by convergence induced by differential surface friction between the land and ocean is believed to be the primary cause for the high frequency along the coast. In contrast, the high frequency over mountainous area is believed to be due to orographic lifting of generally southerly flows during the warm season.

Effect of tides, river flow, and gate operations on entrainment of juvenile salmon into the interior Sacramento–San Joaquin River Delta

Science.gov (United States)

Perry, Russell W.; Brandes, Patricia L.; Burau, Jon R.; Sandstrom, Philip T.; Skalski, John R.

2015-01-01

Juvenile Chinook Salmon Oncorhynchus tshawytscha emigrating from natal tributaries of the Sacramento River, California, must negotiate the Sacramento-San Joaquin River Delta (hereafter, the Delta), a complex network of natural and man-made channels linking the Sacramento River with San Francisco Bay. Fish that enter the interior and southern Delta—the region to the south of the Sacramento River where water pumping stations are located—survive at a lower rate than fish that use alternative migration routes. Consequently, total survival decreases as the fraction of the population entering the interior Delta increases, thus spurring management actions to reduce the proportion of fish that are entrained into the interior Delta. To better inform management actions, we modeled entrainment probability as a function of hydrodynamic variables. We fitted alternative entrainment models to telemetry data that identified when tagged fish in the Sacramento River entered two river channels leading to the interior Delta (Georgiana Slough and the gated Delta Cross Channel). We found that the probability of entrainment into the interior Delta through both channels depended strongly on the river flow and tidal stage at the time of fish arrival at the river junction. Fish that arrived during ebb tides had a low entrainment probability, whereas fish that arrived during flood tides (i.e., when the river's flow was reversed) had a high probability of entering the interior Delta. We coupled our entrainment model with a flow simulation model to evaluate the effect of nighttime closures of the Delta Cross Channel gates on the daily probability of fish entrainment into the interior Delta. Relative to 24-h gate closures, nighttime closures increased daily entrainment probability by 3 percentage points on average if fish arrived at the river junction uniformly throughout the day and by only 1.3 percentage points if 85% of fish arrived at night. We illustrate how our model can be used to

Source Identification and Apportionment of Trace Elements in Soils in the Yangtze River Delta, China.

Science.gov (United States)

Shao, Shuai; Hu, Bifeng; Fu, Zhiyi; Wang, Jiayu; Lou, Ge; Zhou, Yue; Jin, Bin; Li, Yan; Shi, Zhou

2018-06-12

Trace elements pollution has attracted a lot of attention worldwide. However, it is difficult to identify and apportion the sources of multiple element pollutants over large areas because of the considerable spatial complexity and variability in the distribution of trace elements in soil. In this study, we collected total of 2051 topsoil (0⁻20 cm) samples, and analyzed the general pollution status of soils from the Yangtze River Delta, Southeast China. We applied principal component analysis (PCA), a finite mixture distribution model (FMDM), and geostatistical tools to identify and quantitatively apportion the sources of seven kinds of trace elements (chromium (Cr), cadmium (Cd), mercury (Hg), copper (Cu), zinc (Zn), nickel (Ni), and arsenic (As)) in soil. The PCA results indicated that the trace elements in soil in the study area were mainly from natural, multi-pollutant and industrial sources. The FMDM also fitted three sub log-normal distributions. The results from the two models were quite similar: Cr, As, and Ni were mainly from natural sources caused by parent material weathering; Cd, Cu, and Zu were mainly from mixed sources, with a considerable portion from anthropogenic activities such as traffic pollutants, domestic garbage, and agricultural inputs, and Hg was mainly from industrial wastes and pollutants.

Entropy and optimality in river deltas

Science.gov (United States)

Tejedor, Alejandro; Longjas, Anthony; Edmonds, Douglas A.; Zaliapin, Ilya; Georgiou, Tryphon T.; Rinaldo, Andrea; Foufoula-Georgiou, Efi

2017-10-01

The form and function of river deltas is intricately linked to the evolving structure of their channel networks, which controls how effectively deltas are nourished with sediments and nutrients. Understanding the coevolution of deltaic channels and their flux organization is crucial for guiding maintenance strategies of these highly stressed systems from a range of anthropogenic activities. To date, however, a unified theory explaining how deltas self-organize to distribute water and sediment up to the shoreline remains elusive. Here, we provide evidence for an optimality principle underlying the self-organized partition of fluxes in delta channel networks. By introducing a suitable nonlocal entropy rate (nER) and by analyzing field and simulated deltas, we suggest that delta networks achieve configurations that maximize the diversity of water and sediment flux delivery to the shoreline. We thus suggest that prograding deltas attain dynamically accessible optima of flux distributions on their channel network topologies, thus effectively decoupling evolutionary time scales of geomorphology and hydrology. When interpreted in terms of delta resilience, high nER configurations reflect an increased ability to withstand perturbations. However, the distributive mechanism responsible for both diversifying flux delivery to the shoreline and dampening possible perturbations might lead to catastrophic events when those perturbations exceed certain intensity thresholds.

Carbon storage in the Mississippi River delta enhanced by environmental engineering

Science.gov (United States)

Shields, Michael R.; Bianchi, Thomas S.; Mohrig, David; Hutchings, Jack A.; Kenney, William F.; Kolker, Alexander S.; Curtis, Jason H.

2017-11-01

River deltas have contributed to atmospheric carbon regulation throughout Earth history, but functioning in the modern era has been impaired by reduced sediment loads, altered hydrologic regimes, increased global sea-level rise and accelerated subsidence. Delta restoration involves environmental engineering via river diversions, which utilize self-organizing processes to create prograding deltas. Here we analyse sediment cores from Wax Lake delta, a product of environmental engineering, to quantify the burial of organic carbon. We find that, despite relatively low concentrations of organic carbon measured in the cores (about 0.4%), the accumulation of about 3 T m-2 of sediment over the approximate 60 years of delta building resulted in the burial of a significant amount of organic carbon (16 kg m-2). This equates to an apparent organic carbon accumulation rate of 250 +/- 23 g m-2 yr-1, which implicitly includes losses by carbon emissions and erosion. Our estimated accumulation rate for Wax Lake delta is substantially greater than previous estimates based on the top metre of delta sediments and comparable to those of coastal mangrove and marsh habitats. The sedimentation of carbon at the Wax Lake delta demonstrates the capacity of engineered river diversions to enhance both coastal accretion and carbon burial.

Supply Chain Management for Sustainable Development: Perspective from the Greater Pearl River Delta (China)

OpenAIRE

Tsoi, Joyce

2006-01-01

This thesis was submitted for the degree of Doctor of Philosophy and awarded by the University of Hong Kong. This thesis investigates the application and implications of supply chain management as a modern management model in regulating corporate outsourcing activities within the Greater Pearl River Delta. Globalisation has accelerated the application of supply chain management as a mechanism to enhance corporate performance. At the same time this rapid economic development has also accele...

Top-down estimates of benzene and toluene emissions in the Pearl River Delta and Hong Kong, China

Directory of Open Access Journals (Sweden)

X. Fang

2016-03-01

Full Text Available Benzene (C6H6 and toluene (C7H8 are toxic to humans and the environment. They are also important precursors of ground-level ozone and secondary organic aerosols and contribute substantially to severe air pollution in urban areas in China. Discrepancies exist between different bottom-up inventories for benzene and toluene emissions in the Pearl River Delta (PRD and Hong Kong (HK, which are emission hot spots in China. This study provides top-down estimates of benzene and toluene emissions in the PRD and HK using atmospheric measurement data from a rural site in the area, Heshan, an atmospheric transport model, and an inverse modeling method. The model simulations captured the measured mixing ratios during most pollution episodes. For the PRD and HK, the benzene emissions estimated in this study for 2010 were 44 (12–75 and 5 (2–7 Gg yr−1 for the PRD and HK, respectively, and the toluene emissions were 131 (44–218 and 6 (2–9 Gg yr−1, respectively. Temporal and spatial differences between the inversion estimate and four different bottom-up emission estimates are discussed, and it is proposed that more observations at different sites are urgently needed to better constrain benzene and toluene (and other air pollutant emissions in the PRD and HK in the future.

The Impacts of Climate Change in Hong Kong and the Pearl River Delta

International Nuclear Information System (INIS)

Tracy, A.; Trumbull, K.; Loh, C.

2006-11-01

Civic Exchange added climate change to their research agenda some time ago, recognising that it is a cross-cutting issue that will have substantial impact, not only on Hong Kong but on the entire Pearl River Delta. The Hong Kong region is the wealthiest part of China. Along with growing material wealth, Hong Kong's ecological footprint and particularly it's greenhouse gas emissions - have increased exponentially. Therefore, there exists a special responsibility to contribute to finding effective mitigation measures that can help to slow the process; as well as a pressing need to find ways to adapt to those effects of climate change that cannot be forestalled. This paper represents a first attempt to pull together the relevant materials, with the aim of providing a broad-brush view of how climate change may affect Hong Kong, Macao and the Pearl River Delta. The key recommendation is that more region-specific research must be carried out. Civic Exchange has also taken note of the recently published Stern Review, which was commissioned by the United Kingdom government, to assess the economics of climate change. The report calls for urgent action. In this respect, this report therefore doubles as a funding proposal

A Regional Survey of River-plume Sedimentation on the Mississippi River Delta Front

Science.gov (United States)

Courtois, A. J.; Bentley, S. J.; Xu, K.; Georgiou, I. Y.; Maloney, J. M.; Miner, M. D.; Chaytor, J. D.; Smith, J.

2017-12-01

Many studies of the Mississippi River and Delta (MRD) have shown historic declines in sediment load reaching the main river distributaries over the last few decades. Recent studies also reported that 50% of the suspended load during floods is sequestered within the delta. While the impact of declining sediment load on wetland loss is well documented, submarine sedimentary processes on the delta front during this recent period of declining sediment load are understudied. To better understand modern sediment dispersal and deposition across the Mississippi River Delta Front, 31 multicores were collected in June 2017 from locations extending offshore from Southwest Pass, South Pass, and Pass a Loutre (the main river outlets) in water depths of 25-280 m. Core locations were selected based on multibeam bathymetry and morphology collected by the USGS in May 2017; the timing of collection coincided with the end of annual peak discharge on the Mississippi River. This multi-agency survey is the first to study delta-front sedimentary processes regionally with such a wide suite of tools. Target locations for coring included the dominant depositional environments: mudflow lobes, gullies, and undisturbed prodelta. Cores were subsampled at 2 cm intervals and analyzed for Beryllium-7 activity via gamma spectrometry; in such settings, Be-7 can be used as a tracer of sediment recently delivered from fluvial origin. Results indicate a general trend of declining Be-7 activity with increasing distance from source, and in deeper water. Inshore samples near Southwest Pass show the deepest penetration depth of Be-7 into the sediment (24-26 cm), which is a preliminary indicator of rapid seasonal sedimentation. Nearshore samples from South Pass exhibited similar Be-7 penetration depths, with results near Pass a Loutre to 14-16 cm depth. Be-7 remains detectable to 2 cm in water 206 m deep, approximately 20 km from South Pass. Sediment dispersal remains impressive offshore from all three

Occurrence of estrogenic activities in second-grade surface water and ground water in the Yangtze River Delta, China

International Nuclear Information System (INIS)

Shi, Wei; Hu, Guanjiu; Chen, Sulan; Wei, Si; Cai, Xi; Chen, Bo; Feng, Jianfang; Hu, Xinxin; Wang, Xinru; Yu, Hongxia

2013-01-01

Second-grade surface water and ground water are considered as the commonly used cleanest water in the Yangtze River Delta, which supplies centralized drinking water and contains rare species. However, some synthetic chemicals with estrogenic disrupting activities are detectable. Estrogenic activities in the second-grade surface water and ground water were surveyed by a green monkey kidney fibroblast (CV-1) cell line based ER reporter gene assay. Qualitative and quantitative analysis were further conducted to identify the responsible compounds. Estrogen receptor (ER) agonist activities were present in 7 out of 16 surface water and all the ground water samples. Huaihe River and Yangtze River posed the highest toxicity potential. The highest equivalent (2.2 ng E 2 /L) is higher than the predicted no-effect-concentration (PNEC). Bisphenol A (BPA) contributes to greater than 50% of the total derived equivalents in surface water, and the risk potential in this region deserves more attention and further research. -- Highlights: •Estrogenic activities were present in second-grade surface water and ground water. •Most of the detected equivalents were higher than the predicted no-effect-concentration of E 2 . •ER-EQ 20–80 ranges showed that samples in Huaihe River and Yangtze River posed the highest toxicity. •Bisphenol A contributes to most of the instrumentally derived equivalents in surface water. -- Estrogenic activities were observed in second-grade surface water and ground water in Yangtze River Delta, and BPA was the responsible contaminant

Linking rapid erosion of the Mekong River delta to human activities.

Science.gov (United States)

Anthony, Edward J; Brunier, Guillaume; Besset, Manon; Goichot, Marc; Dussouillez, Philippe; Nguyen, Van Lap

2015-10-08

As international concern for the survival of deltas grows, the Mekong River delta, the world's third largest delta, densely populated, considered as Southeast Asia's most important food basket, and rich in biodiversity at the world scale, is also increasingly affected by human activities and exposed to subsidence and coastal erosion. Several dams have been constructed upstream of the delta and many more are now planned. We quantify from high-resolution SPOT 5 satellite images large-scale shoreline erosion and land loss between 2003 and 2012 that now affect over 50% of the once strongly advancing >600 km-long delta shoreline. Erosion, with no identified change in the river's discharge and in wave and wind conditions over this recent period, is consistent with: (1) a reported significant decrease in coastal surface suspended sediment from the Mekong that may be linked to dam retention of its sediment, (2) large-scale commercial sand mining in the river and delta channels, and (3) subsidence due to groundwater extraction. Shoreline erosion is already responsible for displacement of coastal populations. It is an additional hazard to the integrity of this Asian mega delta now considered particularly vulnerable to accelerated subsidence and sea-level rise, and will be exacerbated by future hydropower dams.

Challenges and Approaches in River Delta Planning - report on training workshop

NARCIS (Netherlands)

Wosten, J.H.M.; Douven, W.; Long Phi, H.; Fida Abdullah Khan, M.

2012-01-01

River delta’s, like the Mekong Delta (Vietnam), Ganges-Brahmaputra Delta (Bangladesh), Irrawady (Myanmar) and Ciliwung Delta (Indonesia) are developing rapidly and characterized by large-scale urbanization and industrialization processes. They are facing serious planning challenges related to issues

Bi-objective analysis of water-sediment regulation for channel scouring and delta maintenance: A study of the lower Yellow River

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Kong, D.; Miao, C.; Duan, Q.

2016-12-01

Long-term hydrological data and remotely-sensed satellite images were used to analyze the effects of the water-sediment regulation scheme (WSRS) implemented in the lower Yellow River (LYR), China, between 1983 and 2013. The WSRS aimed to control channel scouring in the LYR and maintain the Yellow River Delta (YRD). Channel erosion in the LYR has primarily depended on the incoming sediment concentration at Xiaolangdi, where the concentration must be lower than approximately 9.17 × 10-3 t m-3 to avoid rising of the riverbed. In 1996, an artificial diversion altered the evolution of the YRD. To maintain delta equilibrium, an average sediment load of about 441 × 106 t year-1 was required before 1996, after which this value decreased to 167 × 106 t year-1. We provide a preliminary estimate of the incoming water and sediment conditions required at the Xiaolangdi station to guarantee both LYR channel scouring and maintenance of the YRD. Our results show that it is feasible to transport sediment originally deposited in the LYR to the river mouth to maintain the delta, which is of great significance for the future management and environmental protection of the LYR.

VOCs and OVOCs distribution and control policy implications in Pearl River Delta region, China

Science.gov (United States)

Louie, Peter K. K.; Ho, Josephine W. K.; Tsang, Roy C. W.; Blake, Donald R.; Lau, Alexis K. H.; Yu, Jian Zhen; Yuan, Zibing; Wang, Xinming; Shao, Min; Zhong, Liuju

2013-09-01

Ambient air measurements of volatile organic compounds (VOCs) and oxygenated volatile organic compounds (OVOCs) were conducted and characterised during a two-year grid study in the Pearl River Delta (PRD) region of southern China. The present grid study pioneered the systematic investigation of the nature and characteristics of complex VOC and OVOC sources at a regional scale. The largest contributing VOCs, accounting over 80% of the total VOCs mixing ratio, were toluene, ethane, ethyne, propane, ethene, butane, benzene, pentane, ethylbenzene, and xylenes. Sub-regional VOC spatial characteristics were identified, namely: i) relatively fresh pollutants, consistent with elevated vehicular and industrial activities, around the PRD estuary; and ii) a concentration gradient with higher mixing ratios of VOCs in the west as compared with the eastern part of PRD. Based on alkyl nitrate aging determination, a high hydroxyl radical (OH) concentration favoured fast hydrocarbon reactions and formation of locally produced ozone. The photochemical reactivity analysis showed aromatic hydrocarbons and alkenes together consisted of around 80% of the ozone formation potential (OFP) among the key VOCs. We also found that the OFP from OVOCs should not be neglected since their OFP contribution was more than one-third of that from VOCs alone. These findings support the choice of current air pollution control policy which focuses on vehicular sources but warrants further controls. Industrial emissions and VOCs emitted by solvents should be the next targets for ground-level ozone abatement.

Risk-based prioritization among air pollution control strategies in the Yangtze River Delta, China.

Science.gov (United States)

Zhou, Ying; Fu, Joshua S; Zhuang, Guoshun; Levy, Jonathan I

2010-09-01

The Yangtze River Delta (YRD) in China is a densely populated region with recent dramatic increases in energy consumption and atmospheric emissions. We studied how different emission sectors influence population exposures and the corresponding health risks, to inform air pollution control strategy design. We applied the Community Multiscale Air Quality (CMAQ) Modeling System to model the marginal contribution to baseline concentrations from different sectors. We focused on nitrogen oxide (NOx) control while considering other pollutants that affect fine particulate matter [aerodynamic diameter pollutants, with reductions of primary PM2.5 from the industry sector and mobile sources showing the greatest benefits of 0.1 fewer deaths per year per ton of emission reduction. Combining estimates of health benefits per ton with potential emission reductions, the greatest mortality reduction of 12,000 fewer deaths per year [95% confidence interval (CI), 1,200-24,000] was associated with controlling primary PM2.5 emissions from the industry sector and reducing sulfur dioxide (SO2) from the power sector, respectively. Benefits were lower for reducing NOx emissions given lower consequent reductions in the formation of secondary PM2.5 (compared with SO2) and increases in ozone concentrations that would result in the YRD. Although uncertainties related to C-R functions are significant, the estimated health benefits of emission reductions in the YRD are substantial, especially for sectors and pollutants with both higher health benefits per unit emission reductions and large potential for emission reductions.

Hydrology and morphology of two river mouth regions (temperate Vistula Delta and subtropical Red River Delta

Directory of Open Access Journals (Sweden)

Zbigniew Pruszak

2005-09-01

Full Text Available The paper presents a comparative analysis of two different river mouths from two different geographical zones (subtropical and temperate climatic regions. One is the multi-branch and multi-spit mouth of the Red River on the Gulf of Tonkin (Vietnam, the other is the smaller delta of the river Vistula on a bay of the Baltic Sea (Poland. The analysis focuses on the similarities and differences in the hydrodynamics between these estuaries and the adjacent coastal zones, the features of sediment transport, and the long-term morphodynamics of the river outlets. Salinity and water level are also discussed, the latter also in the context of the anticipated global effect of accelerated sea level rise. The analysis shows that the climatic and environmental conditions associated with geographical zones give rise to fundamental differences in the generation and dynamic evolution of the river mouths.

Is there a self-organization principle of river deltas?

Science.gov (United States)

Tejedor, Alejandro; Longjas, Anthony; Foufoula-Georgiou, Efi

2017-04-01

River deltas are known to possess a complex topological and flux-partitioning structure which has recently been quantified using spectral graph theory [Tejedor et al., 2015a,b]. By analysis of real and simulated deltas it has also been shown that there is promise in formalizing relationships between this topo-dynamic delta structure and the underlying delta forming processes [e.g., Tejedor et al., 2016]. The question we pose here is whether there exists a first order organizational principle behind the self-organization of river deltas and whether this principle can be unraveled from the co-evolving topo-dynamic structure encoded in the delta planform. To answer this question, we introduce a new metric, the nonlocal Entropy Rate (nER) that captures the information content of a delta network in terms of the degree of uncertainty in delivering fluxes from any point of the network to the shoreline. We hypothesize that if the "guiding principle" of undisturbed deltas is to efficiently and robustly build land by increasing the diversity of their flux pathways over the delta plane, then they would exhibit maximum nonlocal Entropy Rate at states at which geometry and flux dynamics are at equilibrium. At the same time, their nER would be non-optimal at transient states, such as before and after major avulsions during which topology and dynamics adjust to each other to reach a new equilibrium state. We will present our results for field and simulated deltas, which confirm this hypothesis and open up new ways of thinking about self-organization, complexity and robustness in river deltas. One particular connection of interest might have important implications since entropy rate and resilience are related by the fluctuation theorem [Demetrius and Manke, 2005], and therefore our results suggest that deltas might in fact self-organize to maximize their resilience to structural and dynamic perturbations. References: Tejedor, A., A. Longjas, I. Zaliapin, and E. Foufoula

Variability Matters: New Insights into Mechanics of River Avulsions on Deltas and Their Deposits

Science.gov (United States)

Ganti, V.

2015-12-01

River deltas are highly dynamic, often fan-shaped depositional systems that form when rivers drain into a standing body of water. They host over a half billion people and are currently under threat of drowning and destruction by relative sea-level rise, subsidence, and anthropogenic interference. Deltas often develop planform fan shapes through avulsions, whereby major river channel shifts occur via "channel jumping" about a spatial node, thus determining their fundamental length scale. Emerging theories suggest that the size of delta lobes is set by backwater hydrodynamics; however, these ideas are difficult to test on natural deltas, which evolve on centennial to millennial timescales. In this presentation, I will show results from the first laboratory delta built through successive deposition of lobes that maintain a constant size that scales with backwater hydrodynamics. The characteristic size of deltas emerges because of a preferential avulsion node that remains fixed spatially relative to the prograding shoreline, and is a consequence of multiple river floods that produce persistent morphodynamic river-bed adjustment within the backwater zone. Moreover, river floods cause erosion in the lowermost reaches of the alluvial river near their coastline, which may leave erosional boundaries in the sedimentary record that may appear similar to those previously interpreted to be a result of relative sea-level fall. I will discuss the implications of these findings in the context of sustainability management of deltas, decoding their stratigraphic record, and identifying ancient standing bodies of water on other planets such as Mars. Finally, I will place this delta study in a broader context of recent work that highlights the importance of understanding and quantifying variability in sedimentology and geomorphology.

What Role do Hurricanes Play in Sediment Delivery to Subsiding River Deltas?

Science.gov (United States)

Smith, J. E., IV

2016-02-01

James E. Smith IV1, Samuel J. Bentley, Sr.1, Gregg A. Snedden2, Crawford White1 Department of Geology and Geophysics and Coastal Studies Institute, Louisiana State University, Baton Rouge, LA 70803 USA United States Geological Survey, National Wetlands Research Center, Baton Rouge LA 70803 USA The Mississippi River Delta has undergone tremendous land loss over the past century due to natural and anthropogenic influences, a fate shared by many river deltas globally. A globally unprecedented effort to restore and sustain the remaining subaerial portions of the delta is now underway, an endeavor that is expected to cost $50-100B over the next 50 yr. Success of this effort requires a thorough understanding of natural and anthropogenic controls on sediment supply, accumulation, and delta geomorphology. In the Mississippi River Delta, hurricanes have been paradoxically identified as both agents of widespread land loss, and positive influences for marsh vertical sediment accretion. We present the first multi-decadal chronostratigraphic assessment of sediment supply for a major coastal basin of the Mississippi River Delta that assesses both fluvial and hurricane-induced contributions to sediment accumulation in deltaic wetlands. Twenty seven cores have been analyzed for radioisotope geochronology and organic content to establish the chronology of mineral sediment supply to the wetlands over the past 70 years. Our findings indicate that over multidecadal timescales, hurricane-induced sediment delivery may be an important contributor for deltaic wetland vertical accretion, but the contribution from hurricanes to long-term sediment accumulation is substantially less than sediment delivery supplied by existing and planned river-sediment diversions at present-day river-sediment loads.

Mackenzie River Delta morphological change based on Landsat time series

Science.gov (United States)

Vesakoski, Jenni-Mari; Alho, Petteri; Gustafsson, David; Arheimer, Berit; Isberg, Kristina

2015-04-01

Arctic rivers are sensitive and yet quite unexplored river systems to which the climate change will impact on. Research has not focused in detail on the fluvial geomorphology of the Arctic rivers mainly due to the remoteness and wideness of the watersheds, problems with data availability and difficult accessibility. Nowadays wide collaborative spatial databases in hydrology as well as extensive remote sensing datasets over the Arctic are available and they enable improved investigation of the Arctic watersheds. Thereby, it is also important to develop and improve methods that enable detecting the fluvio-morphological processes based on the available data. Furthermore, it is essential to reconstruct and improve the understanding of the past fluvial processes in order to better understand prevailing and future fluvial processes. In this study we sum up the fluvial geomorphological change in the Mackenzie River Delta during the last ~30 years. The Mackenzie River Delta (~13 000 km2) is situated in the North Western Territories, Canada where the Mackenzie River enters to the Beaufort Sea, Arctic Ocean near the city of Inuvik. Mackenzie River Delta is lake-rich, productive ecosystem and ecologically sensitive environment. Research objective is achieved through two sub-objectives: 1) Interpretation of the deltaic river channel planform change by applying Landsat time series. 2) Definition of the variables that have impacted the most on detected changes by applying statistics and long hydrological time series derived from Arctic-HYPE model (HYdrologic Predictions for Environment) developed by Swedish Meteorological and Hydrological Institute. According to our satellite interpretation, field observations and statistical analyses, notable spatio-temporal changes have occurred in the morphology of the river channel and delta during the past 30 years. For example, the channels have been developing in braiding and sinuosity. In addition, various linkages between the studied

Spatial-temporal characteristics of haze and vertical distribution of aerosols over the Yangtze River Delta of China.

Science.gov (United States)

Cao, Yueqian; Zhang, Wu; Wang, Wenjing

2018-04-01

Variation of haze events occurred in the Yangtze River Delta (YRD) of China, the characteristics of meteorological elements and the vertical distribution of aerosols during haze episodes were analyzed by utilizing data of ground observation, radiosonde and CALIPSO. The results illustrate that the frequency of haze events between 1981 and 2010 peaked in winter but bottomed out in summer and decreased from north to south in the YRD region, reaching at the lowest point in "low frequency center" - Shanghai. When haze happened, the most seriously affected area was 2-4km above the ground and the concentrated range of total backscattering coefficient (TBC) that decreased with altitude was 0.8×10 -3 -2.5×10 -3 km -1 ·sr -1 . Particulate depolarization ratio (PDR) was less than 40% in a large part and 93% aerosols over the YRD area were regular particles, while the irregular ones concentrated on 2km above the surface and the irregularity rose up but the diversity diminished when altitude increased. Color ratio (CR) was lower than 1.2 mostly at all altitudes and distributed asymmetrically above the ground. Nearly 80% aerosols under 10km were fine particles (CR1.0) clustered at 2-4km. Large particles (CR>1.2) aggregated in lower troposphere massively yet relatively smaller ones gathered in middle and upper troposphere. In the YRD region, aerosols with more powerful capabilities were wider and less regular than the ones of Northwestern China. Copyright © 2017. Published by Elsevier B.V.

Retrieval of tropospheric NO2 vertical column densities and aerosol optical properties form MAXDOAS measurements in Yangtze River Delta, China

Science.gov (United States)

Hao, Nan; Van. Roozendael, Michel; Ding, Aijun; Zhou, Bin; Hendrick, François; Shen, Yicheng; Wang, Tin; Valks, Pieter

2014-05-01

Air pollution is one of the most important environmental problems in developing Asian countries like China. Due to huge consumption of fossil fuels and rapid increase of traffic emissions in the past decades, many regions in China have been experiencing heavy air pollution. The Yangtze River Delta (YRD) region includes the mega-city Shanghai and the well-industrialized and urbanized areas of Zhejiang Province and Jiangsu Province, with over ten large cities, such as Hangzhou, Suzhou and Nanjing. Covering only 2% land area, this region produces over 20% of China's Gross Domestic Product (GDP) which makes it the most densely populated region and one of the most polluted regions in China. For instance, there more than 60% of a year was haze days with poor visibility in Shanghai over the last few years. In the YRD region, knowledge gaps still exist in the understanding of the source and transport of air pollutants because only few measurement studies have been conducted. MAX-DOAS measurements were performed in Shanghai city center and Wujiang (border of Shanghai and Jiangsu Province) from 2010 to 2012 and in Nanjing (capital of Jiangsu Province) from April 2013. A retrieval algorithm, based on an on-line implementation of the radiative transfer code LIDORT and the optimal estimation technique, has been used to provide information on aerosol extinction vertical profiles. The total aerosol optical depths (AODs) calculated from the retrieved profiles were compared to MODIS, AERONET and local PM measurements. The aerosol information was input to LIDORT to calculate NO2 air mass factors. The retrieved tropospheric NO2 vertical column densities (VCDs) were compared to in-situ and satellite NO2 measurements.

Pen Branch Delta and Savannah River Swamp Hydraulic Model

International Nuclear Information System (INIS)

Chen, K.F.

1999-01-01

The proposed Savannah River Site (SRS) Wetlands Restoration Project area is located in Barnwell County, South Carolina on the southwestern boundary of the SRS Reservation. The swamp covers about 40.5 km2 and is bounded to the west and south by the Savannah River and to the north and east by low bluffs at the edge of the Savannah River floodplain. Water levels within the swamp are determined by stage along the Savannah River, local drainage, groundwater seepage, and inflows from four tributaries, Beaver Dam Creek, Fourmile Branch, Pen Branch, and Steel Creek. Historic discharges of heated process water into these tributaries scoured the streambed, created deltas in the adjacent wetland, and killed native vegetation in the vicinity of the delta deposits. Future releases from these tributaries will be substantially smaller and closer to ambient temperatures. One component of the proposed restoration project will be to reestablish indigenous wetland vegetation on the Pen Branch delta that covers about 1.0 km2. Long-term predictions of water levels within the swamp are required to determine the characteristics of suitable plants. The objective of the study was to predict water levels at various locations within the proposed SRS Wetlands Restoration Project area for a range of Savannah River flows and regulated releases from Pen Branch. TABS-MD, a United States Army Corps of Engineer developed two-dimensional finite element open channel hydraulic computer code, was used to model the SRS swamp area for various flow conditions

A Joint Modeling Analysis of Passengers’ Intercity Travel Destination and Mode Choices in Yangtze River Delta Megaregion of China

Directory of Open Access Journals (Sweden)

Yanli Wang

2016-01-01

Full Text Available Joint destination-mode travel choice models are developed for intercity long-distance travel among sixteen cities in Yangtze River Delta Megaregion of China. The model is developed for all the trips in the sample and also by two different trip purposes, work-related business and personal business trips, to accommodate different time values and attraction factors. A nested logit modeling framework is applied to model trip destination and mode choices in two different levels, where the lower level is a mode choice model and the upper level is a destination choice model. The utility values from various travel modes in the lower level are summarized into a composite utility, which is then specified into the destination choice model as an intercity impedance factor. The model is then applied to predict the change in passenger number from Shanghai to Yangzhou between scenarios with and without high-speed rail service to demonstrate the applicability. It is helpful for understanding and modeling megaregional travel destination and mode choice behaviors in the context of developing country.

Role of sectoral and multi-pollutant emission control strategies in improving atmospheric visibility in the Yangtze River Delta, China.

Science.gov (United States)

Huang, Kan; Fu, Joshua S; Gao, Yang; Dong, Xinyi; Zhuang, Guoshun; Lin, Yanfen

2014-01-01

The Community Multi-scale Air Quality modeling system is used to investigate the response of atmospheric visibility to the emission reduction from different sectors (i.e. industries, traffic and power plants) in the Yangtze River Delta, China. Visibility improvement from exclusive reduction of NOx or VOC emission was most inefficient. Sulfate and organic aerosol would rebound if NOx emission was exclusively reduced from any emission sector. The most efficient way to improve the atmospheric visibility was proven to be the multi-pollutant control strategies. Simultaneous emission reductions (20-50%) on NOx, VOC and PM from the industrial and mobile sectors could result in 0.3-1.0 km visibility improvement. And the emission controls on both NOx (85%) and SO2 (90%) from power plants gained the largest visibility improvement of up to 4.0 km among all the scenarios. The seasonal visibility improvement subject to emission controls was higher in summer while lower in the other seasons. Copyright © 2013 Elsevier Ltd. All rights reserved.

Combined effect of boundary layer recirculation factor and stable energy on local air quality in the Pearl River Delta over southern China.

Science.gov (United States)

Li, Haowen; Wang, Baomin; Fang, Xingqin; Zhu, Wei; Fan, Qi; Liao, Zhiheng; Liu, Jian; Zhang, Asi; Fan, Shaojia

2018-03-01

Atmospheric boundary layer (ABL) has a significant impact on the spatial and temporal distribution of air pollutants. In order to gain a better understanding of how ABL affects the variation of air pollutants, atmospheric boundary layer observations were performed at Sanshui in the Pearl River Delta (PRD) region over southern China during the winter of 2013. Two types of typical ABL status that could lead to air pollution were analyzed comparatively: weak vertical diffusion ability type (WVDAT) and weak horizontal transportation ability type (WHTAT). Results show that (1) WVDAT was featured by moderate wind speed, consistent wind direction, and thick inversion layer at 600~1000 m above ground level (AGL), and air pollutants were restricted in the low altitudes due to the stable atmospheric structure; (2) WHTAT was characterized by calm wind, varied wind direction, and shallow intense ground inversion layer, and air pollutants accumulated in locally because of strong recirculation in the low ABL; (3) recirculation factor (RF) and stable energy (SE) were proved to be good indicators for horizontal transportation ability and vertical diffusion ability of the atmosphere, respectively. Combined utilization of RF and SE can be very helpful in the evaluation of air pollution potential of the ABL. Air quality data from ground and meteorological data collected from radio sounding in Sanshui in the Pearl River Delta showed that local air quality was poor when wind reversal was pronounced or temperature stratification state was stable. The combination of horizontal and vertical transportation ability of the local atmosphere should be taken into consideration when evaluating local environmental bearing capacity for air pollution.

Investing for upgrading: the emergence of financial system of science and technology in China’s Pearl River Delta

OpenAIRE

XIAODONG WANG; CHRISTOF MORSCHER

2016-01-01

This article discusses the recent reform policy in China on setting up new financial system for supporting science and technology innovation. Based on the financial sector development in the Pearl River Delta in China’s Guangdong Province, especially Guangzhou, one pilot city of Chinese Science and Technology Financial System Reform, the article analyses the problems in financial system and makes some suggestion on how to restructure the financial system to meet the financial need of local em...

Challenges and Approaches in River Delta Planning - Annexes to report on training workshop

NARCIS (Netherlands)

Wosten, J.H.M.; Douven, W.; Long Phi, H.; Fida Abdullah Khan, M.

2012-01-01

Programme, participants and all powerpoint presentations of the Delta Alliance Training Workshop: Challenges and approaches in river delta planning, sharing experiences from SE Asian Deltas and the Rhine-Meuse Delta. 22-26 October 2012, WACC, Vietnam National University, Ho Chi Minh City, Vietnam

Modeling study of air pollution due to the manufacture of export goods in China's Pearl River Delta.

Science.gov (United States)

Streets, David G; Yu, Carolyne; Bergin, Michael H; Wang, Xuemei; Carmichael, Gregory R

2006-04-01

The Pearl River Delta is a major manufacturing region on the south coast of China that produces more than dollar 100 billion of goods annually for export to North America, Europe, and other parts of Asia. Considerable air pollution is caused by the manufacturing industries themselves and by the power plants, trucks, and ships that support them. We estimate that 10-40% of emissions of primary SO2, NO(x), RSP, and VOC in the region are caused by export-related activities. Using the STEM-2K1 atmospheric transport model, we estimate that these emissions contribute 5-30% of the ambient concentrations of SO2, NO(x), NO(z), and VOC in the region. One reason that the exported goods are cheap and therefore attractive to consumers in developed countries is that emission controls are lacking or of low performance. We estimate that state-of-the-art controls could be installed at an annualized cost of dollar 0.3-3 billion, representing 0.3-3% of the value of the goods produced. We conclude that mitigation measures could be adopted without seriously affecting the prices of exported goods and would achieve considerable human health and other benefits in the form of reduced air pollutant concentrations in densely populated urban areas.

Conceptual model of sedimentation in the Sacramento-San Joaquin River Delta

Science.gov (United States)

Schoellhamer, David H.; Wright, Scott A.; Drexler, Judith Z.

2012-01-01

Sedimentation in the Sacramento–San Joaquin River Delta builds the Delta landscape, creates benthic and pelagic habitat, and transports sediment-associated contaminants. Here we present a conceptual model of sedimentation that includes submodels for river supply from the watershed to the Delta, regional transport within the Delta and seaward exchange, and local sedimentation in open water and marsh habitats. The model demonstrates feedback loops that affect the Delta ecosystem. Submerged and emergent marsh vegetation act as ecosystem engineers that can create a positive feedback loop by decreasing suspended sediment, increasing water column light, which in turn enables more vegetation. Sea-level rise in open water is partially countered by a negative feedback loop that increases deposition if there is a net decrease in hydrodynamic energy. Manipulation of regional sediment transport is probably the most feasible method to control suspended sediment and thus turbidity. The conceptual model is used to identify information gaps that need to be filled to develop an accurate sediment transport model.

What role do hurricanes play in sediment delivery to subsiding river deltas?

Science.gov (United States)

Smith, James E.; Bentley, Samuel J.; Snedden, Gregg; White, Crawford

2015-01-01

The Mississippi River Delta (MRD) has undergone tremendous land loss over the past century due to natural and anthropogenic influences, a fate shared by many river deltas globally. A globally unprecedented effort to restore and sustain the remaining subaerial portions of the delta is now underway, an endeavor that is expected to cost $50–100B over the next 50 yr. Success of this effort requires a thorough understanding of natural and anthropogenic controls on sediment supply and delta geomorphology. In the MRD, hurricanes have been paradoxically identified as both substantial agents of widespread land loss, and vertical marsh sediment accretion. We present the first multi-decadal chronostratigraphic assessment of sediment supply for a major coastal basin of the MRD that assesses both fluvial and hurricane-induced contributions to sediment accumulation in deltaic wetlands. Our findings indicate that over multidecadal timescales, hurricane-induced sediment delivery may be an important contributor for deltaic wetland vertical accretion, but the contribution from hurricanes to long-term sediment accumulation is substantially less than sediment delivery supplied by existing and planned river-sediment diversions at present-day river-sediment loads.

What Role do Hurricanes Play in Sediment Delivery to Subsiding River Deltas?

Science.gov (United States)

Smith, James E; Bentley, Samuel J; Snedden, Gregg A; White, Crawford

2015-12-02

The Mississippi River Delta (MRD) has undergone tremendous land loss over the past century due to natural and anthropogenic influences, a fate shared by many river deltas globally. A globally unprecedented effort to restore and sustain the remaining subaerial portions of the delta is now underway, an endeavor that is expected to cost $50-100B over the next 50 yr. Success of this effort requires a thorough understanding of natural and anthropogenic controls on sediment supply and delta geomorphology. In the MRD, hurricanes have been paradoxically identified as both substantial agents of widespread land loss, and vertical marsh sediment accretion. We present the first multi-decadal chronostratigraphic assessment of sediment supply for a major coastal basin of the MRD that assesses both fluvial and hurricane-induced contributions to sediment accumulation in deltaic wetlands. Our findings indicate that over multidecadal timescales, hurricane-induced sediment delivery may be an important contributor for deltaic wetland vertical accretion, but the contribution from hurricanes to long-term sediment accumulation is substantially less than sediment delivery supplied by existing and planned river-sediment diversions at present-day river-sediment loads.

Potential Activity of Subglacial Microbiota Transported to Anoxic River Delta Sediments

DEFF Research Database (Denmark)

Cameron, Karen A.; Stibal, Marek; Olsen, Nikoline S.

2017-01-01

-related organisms. Later, a reduction in methane was observed to be paired with the depletion of sulphate, and we hypothesise that sulphate reduction out competed hydrogenotrophic methanogenesis. The structure and diversity of the original CO2/H2-amended incubation communities changed dramatically with a major......The Watson River drains a portion of the SW Greenland ice sheet, transporting microbial communities from subglacial environments to a delta at the head of Søndre Strømfjord. This study investigates the potential activity and community shifts of glacial microbiota deposited and buried under layers...... of sediments within the river delta. A long-term (12-month) incubation experiment was established using Watson River delta sediment under anaerobic conditions, with and without CO2/H2 enrichment. Within CO2/H2-amended incubations, sulphate depletion and a shift in the microbial community to a 52% predominance...

Flood mitigation strategies for the Red River Delta

International Nuclear Information System (INIS)

Hansson, K.; Ekenberg, L.

2002-01-01

The increase of natural disasters and especially floods are escalating economical losses. Governments of both developed and developing countries are therefore concerned with increasing post-disaster liabilities in aiding recovery, repairing infrastructure damage and compensation of victims. In particular, governments of developing countries are ill prepared to cover the financial losses of disasters. Moreover, they often experience difficulties in raising funds for the recovery process. In this article, we identify possible policy strategies for coping with complex environmental and social decisions with flood risk involved; using The Red River Delta in Vietnam as a case for investigating various strategies. The paper is concluded with an outline of a model used for policy scenario simulations as well as some very preliminary results from evaluation of three possible policy strategies for The Red River Delta. (author)

Long Lines Not So Practical in China while Small and Medium Sized Lines Favored

Directory of Open Access Journals (Sweden)

Shao-Ying Chu

2003-05-01

Full Text Available Maglev railroads have taken actual steps in China sincethe cooperation work between Germany and China, whichbrings more prospects to this technology. However, due to variousreasons, large-scaled long lines seem to be not so practicalat present in China, while the small and medium space scaledlines may be the initial alternatives with the booming ofthree super-metropolis groups in China, namely, the ZhujiangRiver Delta, the "Grand Beijing" area and the Yangtze RiverDelta.

Distribution of human papilloma virus genotype prevalence in invasive cervical carcinomas and precancerous lesions in the Yangtze River Delta area, China.

Science.gov (United States)

Wang, Hongyun; Cheng, Xiaodong; Ye, Jing; Xu, Xiuyun; Hong, Ying; Sui, Long; You, Zhixue; Xie, Xing

2018-04-27

This study aimed to provide more information for cancer prevention strategies by determining the distribution of human papilloma virus (HPV) genotype prevalence in invasive cervical carcinoma (ICC) and precancerous lesion patients in the Yangtze River Delta area in China. This multi-centre descriptive cross-sectional study involves four university hospitals in the Jiangzhehu area. Women with histologically confirmed cervical intraepithelial neoplasia (CIN) 1, CIN2, CIN3 or ICC who were diagnosed and treated in the four selected hospitals between February 2012 and April 2014 were eligible for recruitment. The average age of the patients was 40.93 ± 11.87 years old, among whom the youngest was 17 years old and the oldest was 76 years old.Those with immunodeficiency diseases or a previous history of cancer or CIN were excluded. HPV genotyping was performed by a central laboratory. The distribution and age and disease specificity of the HPV genotype prevalence were analysed. Of the 2181 collected samples, 251 were ICC and 1930 were CIN. The mean age of cervical cancer and CIN patients was 40.93 ± 11.8 years (range, 17-76 years). The five most commonly identified HPV types in each lesion class were as follows: CIN1: 52, 58, 16, 33, and CP; CIN2: 16, 58, 52, 33, and 31; CIN3: 16, 58, 33, 52, and 31; and ICC: 16, 58, 18, 52, and 33. CIN1 had an earlier age of onset (30-40 years) than CIN2, CIN3, and cervical cancer. The age of onset of cervical cancer exhibited two peaks at 40-44 and 50-54 years of age. In all infected patients, the frequency of HPV infection with a single type was 62.9%, and with multiple types, it was 38.1%. There was no difference in the frequencies of multiple types amongst the different cervical lesions. The most prevalent genotypes in the investigated area (52, 58, 16 and 18) justify the necessity of anti-HPV vaccination in teenagers and young girls under 24 years old in the Yangtze River Delta area in China. Infection with

Fractionation and ecological risk of metals in urban river sediments in Zhongshan City, Pearl River Delta.

Science.gov (United States)

Cai, Jiannan; Cao, Yingzi; Tan, Haijian; Wang, Yanman; Luo, Jiaqi

2011-09-01

Surface sediments collected from nine urban rivers located in Zhongshan City, Pearl River Delta, were analyzed for total concentration of metals with digestion and chemical fractionation adopting the modified European Community Bureau of Reference (BCR) sequential extraction procedure. The results showed that concentration and fractionation of metals varied significantly among the rivers. The total concentration of eight metals in most rivers did not exceed the China Environmental Quality Standard for Soil, Grade III. The potential ecological risk of metals to rivers were related to the land use patterns, in the order of manufacturing areas > residential areas > agriculture areas. The concentration of Pb in the reducible fraction was relatively high (60.0-84.3%). The dominant proportions of Cd, Zn and Cu were primary in the non-residual fraction (67.0%, 71.8% and 81.4% on average respectively), while the percentages of the residual fractions of Cr and Ni varied over a wide range (43-85% and 24-71% respectively). The approaches of the Håkanson ecological risk index and Secondary Phase Enrichment Factor were applied for ecological risk assessment and metal enrichment calculation. The results indicated Hg and Cd had posed high potential ecological risk to urban rivers in this region. Meanwhile, there was widespread pollution and high enrichment of Cu in river sediments in this region. Multiple regression analysis showed that five water quality parameters (pH, DO, COD(Mn), NH(4)(+)-N, TP) had little influence on the distribution of metal fractionation. This result revealed that the ecological risk of metals was not eliminated along with the improvement in water quality. Correlation studies showed that among the metals, Group A (Cd, As, Pb, Zn Hg, r = 0.730-0.924) and Group B (Cr, Cu, Ni, r = 0.815-0.948) were obtained, and the metal contaminations were from industrial activities rather than residential.

Role of photoexcited nitrogen dioxide chemistry on ozone formation and emission control strategy over the Pearl River Delta, China

Science.gov (United States)

A new hydroxyl radical formation pathway via photo-excited nitrogen dioxide chemistry is incorporated into a chemistry-only box model as well as a 3D air quality model to examine its potential role on ozone formation and emission control strategy over the Pearl River Delta region...

Socioeconomic Drivers of PM2.5 in the Accumulation Phase of Air Pollution Episodes in the Yangtze River Delta of China

Directory of Open Access Journals (Sweden)

Cai-Rong Lou

2016-09-01

Full Text Available Recent studies in PM2.5 sources show that anthropogenic emissions are the main contributors to haze pollution. Due to their essential roles in establishing policies for improving air quality, socioeconomic drivers of PM2.5 levels have attracted increasing attention. Unlike previous studies focusing on the annual PM2.5 concentration (Cyear, this paper focuses on the accumulation phase of PM2.5 during the pollution episode (PMAE in the Yangtze River Delta in China. This paper mainly explores the spatial variations of PMAE and its links to the socioeconomic factors using a geographical detector and simple linear regression. The results indicated that PM2.5 was more likely to accumulate in more developed cities, such as Nanjing and Shanghai. Compared with Cyear, PMAE was more sensitive to socioeconomic impacts. Among the twelve indicators chosen for this study, population density was an especially critical factor that could affect the accumulation of PM2.5 dramatically and accounted for the regional difference. A 1% increase in population density could cause a 0.167% rise in the maximal increment and a 0.214% rise in the daily increase rate of PM2.5. Additionally, industry, energy consumption, and vehicles were also significantly associated with PM2.5 accumulation. These conclusions could serve to remediate the severe PM2.5 pollution in China.

Rapid channel incision of the lower Pearl River (China since the 1990s as a consequence of sediment depletion

Directory of Open Access Journals (Sweden)

X. X. Lu

2007-12-01

Full Text Available This paper reported a dramatic channel incision (>10 m in the deepest cut during the past 10 y or so in the lower Pearl River, the second largest river in terms of water discharge in China. The channel incision had caused changes both in the channel geometry as well as in the river hydraulics. Also, the water exchange between the two major tributaries of the Pearl River, the Xijiang and Beijiang, had been significantly changed due to the channel incision. The rapid channel incision was principally the result of extensive sand mining in the lower Pearl River and the delta region due to the booming economy in the Pearl Delta region. Slight increase of water discharge and significant decrease of sediment load since the early 1990s in both the Xijiang and Beijiang also likely contributed to the observed dramatic river bed downcutting to some extent. This has important implications for river management, as the large Chinese rivers have seen a dramatic depletion of sediment fluxes due to the combined effects of declining rainfall, dam constructions, water diversion, reforestation and afforestation, and sediment mining over the recent decades.

Surficial sediments of the wave-dominated Orange River Delta and ...

African Journals Online (AJOL)

The textural and compositional characteristics of the surficial shelf sediments north and south of the Orange River Delta are reviewed and compared. Sediments are fractionated and dispersed both north- and southwards of the Orange River mouth by wave action, longshore drift and subsurface currents. The mean grain ...

Polychlorinated naphthalenes (PCNs) in the surface soils of the Pearl River Delta, South China: Distribution, sources, and air-soil exchange

International Nuclear Information System (INIS)

Wang Yan; Cheng Zhineng; Li Jun; Luo Chunling; Xu Yue; Li Qilu; Liu Xiang; Zhang Gan

2012-01-01

Polychlorinated naphthalenes (PCNs) are now under review by the Stockholm Convention as a candidate for POPs for their persistence, toxicity, bioaccumulation, and long-range atmospheric transport. Data regarding PCN levels and their environmental fate are sparse in China. The PCN concentration and distribution in soils of the Pearl River Delta were reported, and the average total concentration was 59.9 ± 86.7 pg/g. Tri-CNs was the dominant homologue group, and CN 24 was the most abundant congener. A gradient of PCN levels between more and less developed areas was observed. Based on fugacity fraction results, CN 51 is proposed as a possible source marker for specific combustion emissions. Air-soil exchange of PCNs was estimated by calculating the soil and air fugacity. Fugacity fraction values indicated that tri- to penta-CNs were closer to equilibrium in winter and toward net volatilization in summer, while hexa-CNs experienced net air-to-soil transfer in both seasons. Highlights: ► A gradient of PCN levels between highly and less developed areas was observed. ► CN 51 may be a new specific source indicator compared to other congeners. ► Soil acts as a secondary source in summer and a recipient in winter for PCNs in PRD. ► Low-chlorinated PCNs released from the PRD may transport to North China. - As a potential source during the hot period, low-chlorinated PCNs released from contaminated soils may transport to nearby regions.

Shallow stratigraphy of the Skagit River Delta, Washington, derived from sediment cores

Science.gov (United States)

Grossman, Eric E.; George, Douglas A.; Lam, Angela

2011-01-01

Sedimentologic analyses of 21 sediment cores, ranging from 0.4 to 9.6 m in length, reveal that the shallow geologic framework of the Skagit River Delta, western Washington, United States, has changed significantly since 1850. The cores collected from elevations of 3.94 to -2.41 m (relative to mean lower low water) along four cross-shore transects between the emergent marsh and delta front show relatively similar environmental changes across an area spanning ~75 km2. Offshore of the present North Fork Skagit River and South Fork Skagit River mouths where river discharge is focused by diked channels through the delta, the entire 5–7-km-wide tidal flats are covered with 1–2 m of cross-bedded medium-to-coarse sands. The bottoms of cores, collected in these areas are composed of mud. A sharp transition from mud to a cross-bedded sand unit indicates that the tidal flats changed abruptly from a calm environment to an energetic one. This is in stark contrast to the Martha's Bay tidal flats north of the Skagit Bay jetty that was completed in the 1940s to protect the newly constructed Swinomish Channel from flooding and sedimentation. North of the jetty, mud ranging from 1 to 2 m thick drapes a previously silt- and sand-rich tidal flat. The silty sand is a sediment facies that would be expected there where North Fork Skagit River sedimentation occurred prior to jetty emplacement. This report describes the compositional and textural properties of the sediment cores by using geophysical, photographic, x-radiography, and standard sediment grain-size and carbon-analytical methods. The findings help to characterize benthic habitat structure and sediment transport processes and the environmental changes that have occurred across the nearshore of the Skagit River Delta. The findings will be useful for quantifying changes to nearshore marine resources, including impacts resulting from diking, river-delta channelization, shoreline development, and natural variations in fluvial

City-specific vehicle emission control strategies to achieve stringent emission reduction targets in China's Yangtze River Delta region.

Science.gov (United States)

Zhang, Shaojun; Wu, Ye; Zhao, Bin; Wu, Xiaomeng; Shu, Jiawei; Hao, Jiming

2017-01-01

The Yangtze River Delta (YRD) region is one of the most prosperous and densely populated regions in China and is facing tremendous pressure to mitigate vehicle emissions and improve air quality. Our assessment has revealed that mitigating vehicle emissions of NOx would be more difficult than reducing the emissions of other major vehicular pollutants (e.g., CO, HC and PM 2.5 ) in the YRD region. Even in Shanghai, where the emission control implemented are more stringent than in Jiangsu and Zhejiang, we observed little to no reduction in NOx emissions from 2000 to 2010. Emission-reduction targets for HC, NOx and PM 2.5 are determined using a response surface modeling tool for better air quality. We design city-specific emission control strategies for three vehicle-populated cities in the YRD region: Shanghai and Nanjing and Wuxi in Jiangsu. Our results indicate that even if stringent emission control consisting of the Euro 6/VI standards, the limitation of vehicle population and usage, and the scrappage of older vehicles is applied, Nanjing and Wuxi will not be able to meet the NOx emissions target by 2020. Therefore, additional control measures are proposed for Nanjing and Wuxi to further mitigate NOx emissions from heavy-duty diesel vehicles. Copyright © 2016. Published by Elsevier B.V.

The influence of delta formation mechanism on geotechnical property sequence of the late Pleistocene–Holocene sediments in the Mekong River Delta

Directory of Open Access Journals (Sweden)

Truong Minh Hoang

2016-11-01

Full Text Available The aim of the study was to characterize a variety of microstructure development-levels and geotechnical property sequences of the late Pleistocene–Holocene deposits in the Mekong River delta (MRD, and the paper furthermore discusses the influences of delta formation mechanisms on them. The survey associated the geotechnical engineering and the sedimentary geology of the late Pleistocene–Holocene deposits at five sites and also undifferentiated Pleistocene sediments. A cross-section which was rebuilt in the delta progradation-direction and between the Mekong and Bassac rivers represents the stratigraphy. Each sedimentary unit was formed under a different delta formation mechanism and revealed a typical geotechnical property sequence. The mechanical behaviors of the sediment succession in the tide-dominated delta with significant fluvial-activity and material source tend to be more cohesionless soils and strengths than those in the tide- and wave-dominated delta and even the coast. The particular tendency of the mechanical behavior of the deposit succession can be reasonably estimated from the delta formation mechanism. The characteristics of the clay minerals from the Mekong River produced the argillaceous soil which does not have extremely high plasticity. The microstructure development-levels are low to very high indicating how to choose hydraulic conductivity value, k, for estimating overconsolidation ratio, OCR, by the piezocone penetration tests (CPTU. The OCR of sediments in the delta types strangely change with depth but none less than 1. The post-depositional processes significantly influenced the microstructure development, particularly the dehydrating and oxidizing processes.

Multi-tracer investigation of river and groundwater interactions: a case study in Nalenggele River basin, northwest China

Science.gov (United States)

Xu, Wei; Su, Xiaosi; Dai, Zhenxue; Yang, Fengtian; Zhu, Pucheng; Huang, Yong

2017-11-01

Environmental tracers (such as major ions, stable and radiogenic isotopes, and heat) monitored in natural waters provide valuable information for understanding the processes of river-groundwater interactions in arid areas. An integrated framework is presented for interpreting multi-tracer data (major ions, stable isotopes (2H, 18O), the radioactive isotope 222Rn, and heat) for delineating the river-groundwater interactions in Nalenggele River basin, northwest China. Qualitative and quantitative analyses were undertaken to estimate the bidirectional water exchange associated with small-scale interactions between groundwater and surface water. Along the river stretch, groundwater and river water exchange readily. From the high mountain zone to the alluvial fan, groundwater discharge to the river is detected by tracer methods and end-member mixing models, but the river has also been identified as a losing river using discharge measurements, i.e. discharge is bidirectional. On the delta-front of the alluvial fan and in the alluvial plain, in the downstream area, the characteristics of total dissolved solids values, 222Rn concentrations and δ18O values in the surface water, and patterns derived from a heat-tracing method, indicate that groundwater discharges into the river. With the environmental tracers, the processes of river-groundwater interaction have been identified in detail for better understanding of overall hydrogeological processes and of the impacts on water allocation policies.

InSAR-based detection of McKenzie River Delta Permafrost loss

Science.gov (United States)

Oliver-Cabrera, T.; Wdowinski, S.

2017-12-01

Permafrost underlies most of the McKenzie River, North America's largest delta. The in the delta is catalogued as discontinuous permafrost due to the influence of shifting river channels on near-surface ground temperatures. The area is affected by climate change, studies show that ground temperature has increased by 1.5°C since 1970, due to rising annual mean air temperature. Flooding regimes within the delta are also affected by the changing climate due to melting of near surface ground ice together with sea-level rise increasing the potential of land subsidence. Observed consequences of changes occurring in the region are vegetation growth and northward migration of the tree line. The growing vegetation can affect physical properties of the accumulated snow, including depth, density and thermal conductivity. Thogether these variations affect permafrost stability. Permafrost changes can be measured throughout the impacts on river runoffs, ground water, drainages, carbon release, land subsidence and even infrastructure damages. Degradation of permafrost can also be measured by observing ecological changes in the area. In this study, we use InSAR observations to detect permafrost changes and their transition to wetland or vegetated land cover. Our data consist of four ALOS-PALSAR frames covering the entire McKenzie River Delta with temporal coverage spanning from January 2007 to March of 2011. Each frame has 20 to 24 acquisitions, in which half of the data acquired with HH polarization and the other half with HH+HV. We process the data using ROI_PAC and PYSAR software packages. Preliminary results have detected the following spatial patterns: (1) An overall good coherence of summer interferograms with 46-92 day interferograms, (2) Low coherence of winter interferograms (November to February), probably to the increase in snow coverage, (3) Phase jumps along the border of the river reflecting morphological differences between the region near to the river and other

Recent Niger Delta shoreline response to Niger River hydrology: Conflict between forces of Nature and Humans

Science.gov (United States)

Dada, Olusegun A.; Li, Guangxue; Qiao, Lulu; Asiwaju-Bello, Yinusa Ayodele; Anifowose, Adeleye Yekini Biodun

2018-03-01

The Niger River Delta is a prolific hydrocarbon province and a mega-delta of economic and environmental relevance. To understand patterns of its recent shoreline evolution (1923-2013) in response to the Niger River hydrology, and establish the role played by forces of Nature and Human, available topographic and satellite remote sensing data, combined with hydro-climatic (rainfall and runoff) data were analyzed. Results indicate that the entire delta coastline dramatically receded: 82% of the >400 km-long coast retreated, during the period 1950-1987; and 69% between 2007 and 2012. Prior to 1950, there was a continuation of seaward advancement along 53-74% of the delta coast. The 1950-1987 shoreline recession coincided with occurrences of two major events in the Niger River basin; these are downward trends in hydro-climatic conditions (the great droughts of the 1970s-1980s), and dam construction on the Lower Niger River at Kainji (1964-1968). The 2007-2012 event corresponded with the extensive channel dredging during 2009-2012 in the Lower Niger River from the coastal town of Warri in the south to Baro in the north. Remarkably, the largest net shoreline advancement recorded in 74% of the entire delta area occurred within a year (2012-2013), which we link to increased sediment supply to the coast caused by the '2012' floods, adjudged the worst floods in the entire Niger River Basin in the last few decades. With both anthropogenic and environmental factors inducing delta evolution, only innovative river and coastal management can determine the fortune of the future coastal development of the Niger Delta.

Human influence on the sedimentation in the delta of the river Kyroenjoki, western Finland

International Nuclear Information System (INIS)

Heikkilae, R.

1999-01-01

Human activities in the drainage basin of the river Kyroenjoki, Western Finland, have greatly influenced the hydrology and sediment load of the river. The main factors have been agriculture, forestry, peat mining and watercourse works. Also sewage from towns and small-scale industry has increased the nutrient transport to the delta of the river. The aim of this study was to assess factors influencing the sedimentary conditions, sediment accumulation rates and sediment quality in the delta of the river. The sediment studies were carried out in 1983-1988 in the delta. The drainage basin of the river Kyroenjoki covers 5030 km 2 in the middle boreal vegetation zone. The river channel has been cleared many times since the 1600s to prevent floods and to allow agriculture on the adjoining land. Extensive cultivation of the paludified Litorina clay plains along the river has also continued for centuries. Forestry drainage of mires covered almost all the mires of the basin in 1960s and 1970s. Since 1963, four reservoirs and four hydroelectric power stations with daily regulation of water have been built. The estuary of the river was echo sounded, and on the basis of the results the delta was delimited, and areas of accumulation and erosion were separated. Samples of the sediment surface from 65 sites and long cores from 8 sites in the delta of the river Kyroenjoki were analysed for water content, organic content, C, N, P, Ca, Fe, Mn, Pb, Cu, Zn, Cd and Hg. The sediment from Nabbviken Bay in the delta was dated on the basis of annual laminae. The chemical analyses showed that the organic matter and heavy metal content have increased during recent decades. The heavy metal content was clearly lower than in areas polluted by industrial works. The phosphorus content of the sediment was very high. The sedimentation rate in the delta increased from the 1930s to the 1950s, due to increased land reclamation for agriculture and forestry drainage, and then decreased in the beginning

Impacts of Declining Mississippi River Sediment Load on Subaqueous Delta Front Sedimentation and Geomorphology

Science.gov (United States)

Maloney, J. M.; Bentley, S. J.; Xu, K.; Georgiou, I. Y.; Miner, M. D.

2016-02-01

The Mississippi River delta system is undergoing unprecedented changes due to the effects of climate change and anthropogenic alterations to the river and its delta. Since the 1950s, the suspended sediment load of the Mississippi River has decreased by approximately 50% due to the construction of >50,000 dams in the Mississippi basin. The impact of this decreased sediment load has been observed in subaerial environments, but the impact on sedimentation and geomorphology of the subaqueous delta front has yet to be examined. To identify historic trends in sedimentation patterns, we compiled bathymetric datasets, including historical charts, industry and academic surveys, and NOAA data, collected between 1764 and 2009. Sedimentation rates are variable across the delta front, but are highest near the mouth of Southwest Pass, which carries the largest percentage of Mississippi River flow and sediment into the Gulf of Mexico. The progradation rate of Southwest Pass (measured at the 10 m depth contour) has slowed from 67 m/yr between 1764 and 1940 to 26 m/yr between 1940 and 1979, with evidence of further deceleration from 1979-2009. Decreased rates of progradation are also observed at South Pass and Pass A Loutre, with the 10 m contour retreating at rates >20 m/yr at both passes. Advancement of the delta front also decelerated in deeper water (15-90 m) offshore from Southwest Pass. In this area, from 1940-1979, depth contours advanced seaward 30 m/yr, but rates declined from 1979-2005. Furthermore, over the same area, the sediment accumulation rate decreased by 81% for the same period. The Mississippi River delta front appears to be entering a phase of decline, which will likely be accelerated by future upstream management practices. This decline has implications for offshore ecosystems, biogeochemical cycling, pollutant dispersal, mudflow hazard, and the continued use of the delta as an economic and population center.

Anthropogenic CO2 emissions from a megacity in the Yangtze River Delta of China.

Science.gov (United States)

Hu, Cheng; Liu, Shoudong; Wang, Yongwei; Zhang, Mi; Xiao, Wei; Wang, Wei; Xu, Jiaping

2018-06-03

Anthropogenic CO 2 emissions from cities represent a major source contributing to the global atmospheric CO 2 burden. Here, we examined the enhancement of atmospheric CO 2 mixing ratios by anthropogenic emissions within the Yangtze River Delta (YRD), China, one of the world's most densely populated regions (population greater than 150 million). Tower measurements of CO 2 mixing ratios were conducted from March 2013 to August 2015 and were combined with numerical source footprint modeling to help constrain the anthropogenic CO 2 emissions. We simulated the CO 2 enhancements (i.e., fluctuations superimposed on background values) for winter season (December, January, and February). Overall, we observed mean diurnal variation of CO 2 enhancement of 23.5~49.7 μmol mol -1 , 21.4~52.4 μmol mol -1 , 28.1~55.4 μmol mol -1 , and 29.5~42.4 μmol mol -1 in spring, summer, autumn, and winter, respectively. These enhancements were much larger than previously reported values for other countries. The diurnal CO 2 enhancements reported here showed strong similarity for all 3 years of the study. Results from source footprint modeling indicated that our tower observations adequately represent emissions from the broader YRD area. Here, the east of Anhui and the west of Jiangsu province contributed significantly more to the anthropogenic CO 2 enhancement compared to the other sectors of YRD. The average anthropogenic CO 2 emission in 2014 was 0.162 (± 0.005) mg m -2  s -1 and was 7 ± 3% higher than 2010 for the YRD. Overall, our emission estimates were significantly smaller (9.5%) than those estimated (0.179 mg m -2  s -1 ) from the EDGAR emission database.

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

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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.

Ground-level ozone in the Pearl River Delta and the roles of VOC and NO(x) in its production.

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Shao, Min; Zhang, Yuanhang; Zeng, Limin; Tang, Xiaoyan; Zhang, Jing; Zhong, Liuju; Wang, Boguang

2009-01-01

In many regions of China, very rapid economic growth has been accompanied by air pollution caused by vehicle emissions. In one of these regions, the Pearl River Delta, the variations of ground-level ozone and its precursors were investigated. Overall, the ambient concentrations of NO(2) increased quickly between 1995 and 1996, but then slightly decreased due to stringent nitrogen oxide (NO(x)) emission controls. Nonetheless, ambient NO(2) levels in the Pearl River Delta remained high. The regional average concentrations of volatile organic compounds (VOCs) were 290 ppbC in summer and 190 ppbC in autumn. Local emissions and long-distance transportation of pollutants play important roles in the regional distribution of VOCs. Ambient O(3) production is significant in urban areas and also downwind of cities. The relative incremental reactivities (RIRs), determined by an observation-based model, showed that ground-level ozone formation in the Guangzhou urban area is generally limited by the concentrations of VOCs, but there are also measurable impacts of NO(x).

NDVI indicated characteristics of vegetation cover change in China's metropolises over the last three decades.

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Sun, Jinyu; Wang, Xuhui; Chen, Anping; Ma, Yuecun; Cui, Mengdi; Piao, Shilong

2011-08-01

How urban vegetation was influenced by three decades of intensive urbanization in China is of great interest but rarely studied. In this paper, we used satellite derived Normalized Difference Vegetation Index (NDVI) and socioeconomic data to evaluate effects of urbanization on vegetation cover in China's 117 metropolises over the last three decades. Our results suggest that current urbanization has caused deterioration of urban vegetation across most cities in China, particularly in East China. At the national scale, average urban area NDVI (NDVI(u)) significantly decreased during the last three decades (P NDVI(u) did not show statistically significant trend before 1990 but decrease remarkably after 1990 (P NDVI(u) turning point. The year when NDVI(u) started to decline significantly for Central China and East China was 1987 and 1990, respectively, while NDVI(u) in West China remained relatively constant until 1998. NDVI(u) changes in the Yangtze River Delta and the Pearl River Delta, two regions which has been undergoing the most rapid urbanization in China, also show different characteristics. The Pearl River Delta experienced a rapid decline in NDVI(u) from the early 1980s to the mid-1990s; while in the Yangtze River Delta, NDVI(u) did not decline significantly until the early 1990s. Such different patterns of NDVI(u) changes are closely linked with policy-oriented difference in urbanization dynamics of these regions, which highlights the importance of implementing a sustainable urban development policy.

Passive air sampling of organochlorine pesticides and polychlorinated biphenyls in the Yangtze River Delta, China: Concentrations, distributions, and cancer risk assessment

International Nuclear Information System (INIS)

Zhang, Lifei; Dong, Liang; Yang, Wenlong; Zhou, Li; Shi, Shuangxin; Zhang, Xiulan; Niu, Shan; Li, Lingling; Wu, Zhongxiang; Huang, Yeru

2013-01-01

The Yangtze River Delta (YRD) has been quickly industrialized and urbanized. Passive air sampling of organochlorine pesticides (OCPs) and polychlorinated biphenyls (PCBs) was carried out in the YRD in 2010–2011 to investigate their spatiotemporal distributions and estimate the risk of cancer from their inhalation. Annual concentrations were 151, 168, 18.8, 110, 17.9, and 35.0 pg m −3 for HCB, ∑DDTs, ∑HCHs, ∑chlordane, mirex, and PCBs, respectively. The highest OCP and PCB concentrations were generally detected in the autumn and winter. The average concentrations of OCPs and PCBs for the different site groups followed the order urban ≈ urban–rural transition > rural. The lifetime excess cancer risks from the inhalation of OCPs and PCBs were −6 . The predicted cancer cases per lifetime associated with the inhalation of OCPs and PCBs are 12, 7, and 4 per ten thousand people for urban, urban–rural transition, and rural areas, respectively. Highlights: •Organochlorine pollutants were measured in the air in the Yangtze River Delta area. •Air PCB concentration declined in recent years comparing with previous results. •HCB and DDEs predominated, with the highest values in winter and autumn, respectively. •OCPs and PCBs followed the order: urban ≈ urban–rural transition > rural. -- A detailed study of organochlorine pesticides and polychlorinated biphenyls in air across the Yangtze River Delta area using passive air samplers

Characteristis of Soil Water and Salt Spatial Variations in the Spring Season in Typical Yellow River Delta Areas of Kenli County, China

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WANG Zhuo-ran

2015-04-01

Full Text Available The Yellow River Delta as an important area of reserved land resources, is faced with the problem of soil salinization. Grasping the status of soil water and salt as well as their spatial variation rules is an important foundation of prevention, control and use of soil salinization. This study selected Kenli County of the Yellow River Delta, obtained soil water and salt content data through field survey and lab experiments, and analyzed the status of soil water and salt as well as their spatial variation rules using statistics, GIS interpolation and buffer analysis methods. The results showed that the general salt content in the study area was mainly moderate. Salt content increased from soil surfacelayer to underlayer and salt content in each layer was significantly correlated. The areas with high saltness in surfacelayer, middlelayer and underlayer soil mainly distributed in the east near the Bohai Sea in Kenli County, while the areas with lower saltness mainly distributed in the southwest. Soil salt contents showed the trends of decrease, and soil water contents showed the trends of decrease first and then increase with the increase in distance to Bohai Sea. Stretching from the Yellow River, soil salt content showed increase tendency with the increase in distance to the Yellow River, and water content decreased first and then increased. The order from high saltness to low of different vegetation types was naked land>suaeda glauca>tamarix>vervain>reed>couch grass>paddy>cotton>winter wheat>maize, the order of different geomorphic types was depression>slightly sloping ground>slow hillock>beach heights. This study preliminary delineates soil water and salt status as well as their spatial variation rules in the spring season of the study area, and provides scientific basis for soil resource sustainable utilization in the Yellow River Delta.

Contamination of phthalate esters, organochlorine pesticides and polybrominated diphenyl ethers in agricultural soils from the Yangtze River Delta of China.

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Sun, Jianteng; Pan, Lili; Zhan, Yu; Lu, Hainan; Tsang, Daniel C W; Liu, Wenxin; Wang, Xilong; Li, Xiangdong; Zhu, Lizhong

2016-02-15

To reveal the pollution status associated with rapid urbanization and economic growth, extensive areas of agricultural soils (approximately 45,800 km(2)) in the Yangtze River Delta of China were investigated with respect to selected endocrine disruptor compounds (EDCs), including phthalate esters (PAEs), organochlorine pesticides (OCPs) and polybrominated diphenyl ethers (PBDEs). The residues of sum of 15 PAEs, sum of 15 OCPs and sum of 13 PBDEs were in the range of 167-9370 ng/g, 1.0-3520 ng/g, and usage and recent input. Agricultural plastic film was considered to be an important source of PAEs. Discharge from furniture industry was potential major source of PBDEs in this region. The selected pollutants showed quite different spatial distributions within the studied region. It is worth noting that much higher concentrations of the EDCs were found on the borders between Shanghai and the two neighboring provinces, where agriculture and industry developed rapidly in recent years. Contaminants from both agricultural and industrial activities made this area a pollution hotspot, which should arouse more stringent regulation to safeguard the environment and food security. Copyright © 2015 Elsevier B.V. All rights reserved.

More than 100 Years of Background-Level Sedimentary Metals, Nisqually River Delta, South Puget Sound, Washington

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Takesue, Renee K.; Swarzenski, Peter W.

2011-01-01

The Nisqually River Delta is located about 25 km south of the Tacoma Narrows in the southern reach of Puget Sound. Delta evolution is controlled by sedimentation from the Nisqually River and erosion by strong tidal currents that may reach 0.95 m/s in the Nisqually Reach. The Nisqually River flows 116 km from the Cascade Range, including the slopes of Mount Rainier, through glacially carved valleys to Puget Sound. Extensive tidal flats on the delta consist of late-Holocene silty and sandy strata from normal river streamflow and seasonal floods and possibly from distal sediment-rich debris flows associated with volcanic and seismic events. In the early 1900s, dikes and levees were constructed around Nisqually Delta salt marshes, and the reclaimed land was used for agriculture and pasture. In 1974, U.S. Fish and Wildlife Service established the Nisqually National Wildlife Refuge on the reclaimed land to protect migratory birds; its creation has prevented further human alteration of the Delta and estuary. In October 2009, original dikes and levees were removed to restore tidal exchange to almost 3 km2 of man-made freshwater marsh on the Nisqually Delta.

Light Absorption of Brown Carbon Aerosol in the Pearl River Delta Region of China

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Huang, X.

2015-12-01

X.F. Huang, J.F. Yuan, L.M. Cao, J. Cui, C.N. Huang, Z.J. Lan and L.Y. He Key Laboratory for Urban Habitat Environmental Science and Technology, School of Environment and Energy, Peking University Shenzhen Graduate School, Shenzhen 518055, ChinaCorresponding author. Tel.: +86 755 26032532; fax: +86 755 26035332. E-mail address: huangxf@pku.edu.cn (X. F. Huang). Abstract: The strong spectral dependence of light absorption of brown carbon (BrC) aerosol has been recognized in recent decades. The Absorption Angstrom Exponent (AAE) of ambient aerosol was widely used in previous studies to attribute light absorption of brown carbon at shorter wavelengths, with a theoretical assumption that the AAE of black carbon (BC) aerosol equals to unit. In this study, the AAE method was improved by statistical extrapolation based on ambient measurements in the polluted seasons in typical urban and rural areas in the Pearl River Delta (PRD) region of China. A three-wavelength photoacoustic soot spectrometer (PASS-3) and an aerosol mass spectrometer (AMS) were used to explore the relationship between the ambient measured AAE and the ratio of organic aerosol to BC aerosol, in order to extract the more realistic AAE by pure BC aerosol, which were found to be 0.86, 0.82 and 1.02 at 405nm and 0.70, 0.71, and 0.86 at 532nm in the campaigns of urban-winter, urban-fall, and rural-fall, respectively. Roadway tunnel experiment results further supported the effectiveness of the obtained AAE for pure BC aerosol. In addition, biomass burning experiments proved higher spectral dependence of more-BrC environment and further verified the reliability of the instruments' response. Then, the average light absorption contribution of BrC aerosol was calculated to be 11.7, 6.3 and 12.1% (with total relative uncertainty of 7.5, 6.9 and 10.0%) at 405nm and 10.0, 4.1 and 5.5% (with total relative uncertainty of 6.5, 8.6 and 15.4%) at 532nm of the three campaigns, respectively. These results indicate that the

Implementing Integrated River Basin Management in China

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Dorri G. J. te Boekhorst

2010-06-01

Full Text Available This paper examines the role of the World Wildlife Fund for Nature China as policy entrepreneur in China. It illustrates the ways in which the World Wildlife Fund for Nature is active in promoting integrated river basin management in the Yangtze River basin and how the efforts at basin level are matched with the advice of the China Council for International Cooperation on Environment and Development task force on integrated river basin management to the national government of China. This article demonstrates that the World Wildlife Fund for Nature uses various strategies of different types to support a transition process towards integrated river basin management. Successful deployment of these strategies for change in environmental policy requires special skills, actions, and attitudes on the part of the policy entrepreneur, especially in China, where the government has a dominant role regarding water management and the position of policy entrepeneurs is delicate.

High resolution of black carbon and organic carbon emissions in the Pearl River Delta region, China.

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Zheng, Junyu; He, Min; Shen, Xingling; Yin, Shasha; Yuan, Zibing

2012-11-01

A high-resolution regional black carbon (BC) and organic carbon (OC) emission inventory for the year 2009 was developed for the Pearl River Delta (PRD) region, China, based on the collected activity data and the latest emission factors. PM(2.5), BC and OC emissions were estimated to be 303 kt, 39 kt and 31 kt, respectively. Industrial processes were major contributing sources to PM(2.5) emissions. BC emissions were mainly from mobile sources, accounting for 65.0%, while 34.1% of OC emissions were from residential combustion. The primary OC/BC ratios for individual cities in the PRD region were dependent on the levels of economic development due to differences in source characteristics, with high ratios in the less developed cities and low ratios in the central and southern developed areas. The preliminary temporal profiles were established, showing the highest OC emissions in winter and relatively constant BC emissions throughout the year. The emissions were spatially allocated into grid cells with a resolution of 3 km × 3 km. Large amounts of BC emissions were distributed over the central-southern PRD city clusters, while OC emissions exhibited a relatively even spatial distribution due to the significant biomass burning emissions from the outlying area of the PRD region. Uncertainties in carbonaceous aerosol emissions were usually higher than in other primary pollutants like SO(2), NO(x), and PM(10). One of the key uncertainty sources was the emission factor, due to the absence of direct measurements of BC and OC emission rates. Copyright © 2012 Elsevier B.V. All rights reserved.

Urbanization effect on precipitation over the Pearl River Delta based on CMORPH data

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Sheng Chen

2015-03-01

Full Text Available Based on the satellite data from the Climate Prediction Center morphing (CMORPH at very high spatial and temporal resolution, the effects of urbanization on precipitation were assessed over the Pearl River Delta (PRD metropolitan regions of China. CMORPH data well estimates the precipitation features over the PRD. Compared to the surrounding rural areas, the PRD urban areas experience fewer and shorter precipitation events with a lower precipitation frequency (ratio of rainy hours, about 3 days per year less; however, short-duration heavy rain events play a more significant role over the PRD urban areas. Afternoon precipitation is much more pronounced over the PRD urban areas than the surrounding rural areas, which is probably because of the increase in short-duration heavy rain over urban areas.

Insights into characteristics, sources, and evolution of submicron aerosols during harvest seasons in the Yangtze River delta region, China

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Zhang, Y. J.; Tang, L. L.; Wang, Z.; Yu, H. X.; Sun, Y. L.; Liu, D.; Qin, W.; Canonaco, F.; Prévôt, A. S. H.; Zhang, H. L.; Zhou, H. C.

2015-02-01

Atmospheric submicron particulate matter (PM1) is one of the most significant pollution components in China. Despite its current popularity in the studies of aerosol chemistry, the characteristics, sources and evolution of atmospheric PM1 species are still poorly understood in China, particularly for the two harvest seasons, namely, the summer wheat harvest and autumn rice harvest. An Aerodyne Aerosol Chemical Speciation Monitor (ACSM) was deployed for online monitoring of PM1 components during summer and autumn harvest seasons in urban Nanjing, in the Yangtze River delta (YRD) region of China. PM1 components were shown to be dominated by organic aerosol (OA, 39 and 41%) and nitrate (23 and 20%) during the harvest seasons (the summer and autumn harvest). Positive matrix factorization (PMF) analysis of the ACSM OA mass spectra resolved four OA factors: hydrocarbon-like mixed with cooking-related OA (HOA + COA), fresh biomass-burning OA (BBOA), oxidized biomass-burning-influenced OA (OOA-BB), and highly oxidized OA (OOA); in particular the oxidized BBOA contributes ~80% of the total BBOA loadings. Both fresh and oxidized BBOA exhibited apparent diurnal cycles with peak concentration at night, when the high ambient relative humidity and low temperature facilitated the partitioning of semi-volatile organic species into the particle phase. The fresh BBOA concentrations for the harvests are estimated as BBOA = 15.1 × (m/z 60-0.26% × OA), where m/z (mass-to-charge ratio) 60 is a marker for levoglucosan-like species. The (BBOA + OOA-BB)/ΔCO, (ΔCO is the CO minus background CO), decreases as a function of f44 (fraction of m/z 44 in OA signal), which might indicate that BBOA was oxidized to less volatile OOA, e.g., more aged and low volatility OOA (LV-OOA) during the aging process. Analysis of air mass back trajectories indicates that the high BB pollutant concentrations are linked to the air masses from the western (summer harvest) and southern (autumn harvest) areas.

2009-2010 USACE Vicksburg District Lidar: Mississippi River Delta

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National Oceanic and Atmospheric Administration, Department of Commerce — LiDAR collected at 1.0 points per square meter (1.0m GSD) for the entire portion of the Mississippi River Delta in the Vicksburg District. This area was flown during...

Occurrence, sources, and ecological risks of PBDEs, PCBs, OCPs, and PAHs in surface sediments of the Yangtze River Delta city cluster, China.

Science.gov (United States)

Zhang, Ting; Yang, Wen-Long; Chen, She-Jun; Shi, Dian-Long; Zhao, Hu; Ding, Yi; Huang, Ye-Ru; Li, Nan; Ren, Yue; Mai, Bi-Xian

2014-08-01

Polybrominated diphenyl ethers (PBDEs), organochlorine pesticides (OCPs), polychlorinated biphenyls (PCBs), and polycyclic aromatic hydrocarbons (PAHs) in 25 surface sediments in three cities (Nantong, Wuxi, and Suzhou) in the Yangtze River Delta, eastern China were measured. The mean concentrations were 378, 45.8, 1.98, 4,002 ng/g for PBDEs, OCPs, PCBs, and PAHs, respectively. Their levels in the sediments in the three cities were generally consistent with the city industrialization. PBDEs and OCPs were markedly dominated by deca-BDE (>90 %) and DDTs (>70 %). A principle component analysis of the analytes identified three major factors suggesting different sources of the contaminants in the sediments. PBDEs and the organic carbon in the sediments have common sources from industrial activities; whereas OCPs and PCBs, correlated with the second factor, were mainly from historical sources. The third factor with loadings of PAHs is indicative of various combustion sources. Ecological risk assessment indicated that the potential highest risk is from DDTs, for which 22 sites exceed the effects range low (ERL) values and three sites exceed the effects range median (ERM) value.

SPATIO-TEMPORAL VARIATION OF MERCURY IN BIDYADHARI RIVER OF SUNDARBAN DELTA, INDIA

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Shivaji Bhattacharya

2014-06-01

Full Text Available Bidyadhari river originates in Nadia district of West Bengal, India and then flows through North 24 Parganas district and now serves as a sewage and excess rainwater outlet from the city of Kolkata and adjacent area, which ultimately empties at the Bay of Bengal through the Indian Sundarban delta. Four different stations situated around the course of the river at considerable distances have been selected from the outfall of sewage canals at Kulti-Ghushighata (S1, where metropolitan sewages discharged and mixed up into water of Bidyadhari river, which ultimately carried through this river via stations Malancha (S2, Kanmari (S3 to Dhamakhali (S4, just before the river confluences with the larger Raimangal river at northern Sundarban delta. This study was conducted to estimate total mercury (Hg concentration in waters (during high tides and ebb tides and sediments of Bidyadhari river in pre-monsoon, monsoon and post-monsoon seasons during the period from March, 2012 to February, 2013 at those stations. It is revealed from the estimated data that agricultural runoff, sewage, effluents from various industries and Kolkata metropolitan, Salt Lake City and adjacent areas of North 24 Parganas district carried and discharged in Bidyadhari river through sewage canals are not so high in mercury content for sediment contamination but alarming in respect of water quality, which crosses the permissible limit of Hg for consumption (0.001 ppm in wide range of areas at Kanmari and Dhamakhali around the estuary. Enhancement of Hg level in this river water and transportation of the metal through tidal effects to and fro mangrove land of Sundarban may be dangerous for aquatic lives and supposed to be grave concern for the ecology of the Sundarban delta including humans

An appraisal of river erosion mitigation in the Niger Delta

International Nuclear Information System (INIS)

Aban, T. K. S.; Omuso, W. O.

1999-01-01

River erosion processes in the Niger Delta and the effectiveness of locally applied remedial measures is appraised, using information on channel geometry, flow velocity distribution, soil type, stratification, bank height and steepness, state of compaction, together with pool level variation in river channels. High flow velocity and bank height were identified as the major erosion causative factors. Local responses towards erosion mitigation have involved structural methods to varying degree of success. River training has been recommended as a long - term regional approach to mitigate river bank erosion. However, in the short -term revetments, concrete and sheets piles may be applied cautiously

Geomorphic change and sediment transport during a small artificial flood in a transformed post-dam delta: The Colorado River delta, United States and Mexico

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Mueller, Erich R.; Schmidt, John C.; Topping, David J.; Shafroth, Patrick B.; Rodríguez-Burgueño, Jesús Eliana; Ramírez-Hernández, Jorge; Grams, Paul E.

2017-01-01

The Colorado River delta is a dramatically transformed landscape. Major changes to river hydrology and morpho-dynamics began following completion of Hoover Dam in 1936. Today, the Colorado River has an intermittent and/or ephemeral channel in much of its former delta. Initial incision of the river channel in the upstream ∼50 km of the delta occurred in the early 1940s in response to spillway releases from Hoover Dam under conditions of drastically reduced sediment supply. A period of relative quiescence followed, until the filling of upstream reservoirs precipitated a resurgence of flows to the delta in the 1980s and 1990s. Flow releases during extreme upper basin snowmelt in the 1980s, flood flows from the Gila River basin in 1993, and a series of ever-decreasing peak flows in the late 1990s and early 2000s further incised the upstream channel and caused considerable channel migration throughout the river corridor. These variable magnitude post-dam floods shaped the modern river geomorphology. In 2014, an experimental pulse-flow release aimed at rejuvenating the riparian ecosystem and understanding hydrologic dynamics flowed more than 100 km through the length of the delta’s river corridor. This small artificial flood caused localized meter-scale scour and fill of the streambed, but did not cause further incision or significant bank erosion because of its small magnitude. Suspended-sand-transport rates were initially relatively high immediately downstream from the Morelos Dam release point, but decreasing discharge from infiltration losses combined with channel widening downstream caused a rapid downstream reduction in suspended-sand-transport rates. A zone of enhanced transport occurred downstream from the southern U.S.-Mexico border where gradient increased, but effectively no geomorphic change occurred beyond a point 65 km downstream from Morelos Dam. Thus, while the pulse flow connected with the modern estuary, deltaic sedimentary processes were not

Spatial genetic structure in natural populations of Phragmites australis in a mosaic of saline habitats in the Yellow River Delta, China.

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Lexuan Gao

Full Text Available Determination of spatial genetic structure (SGS in natural populations is important for both theoretical aspects of evolutionary genetics and their application in species conservation and ecological restoration. In this study, we examined genetic diversity within and among the natural populations of a cosmopolitan grass Phragmites australis (common reed in the Yellow River Delta (YRD, China, where a mosaic of habitat patches varying in soil salinity was detected. We demonstrated that, despite their close geographic proximity, the common reed populations in the YRD significantly diverged at six microsatellite loci, exhibiting a strong association of genetic variation with habitat heterogeneity. Genetic distances among populations were best explained as a function of environmental difference, rather than geographical distance. Although the level of genetic divergence among populations was relatively low (F'(ST =0.073, weak but significant genetic differentiation, as well as the concordance between ecological and genetic landscapes, suggests spatial structuring of genotypes in relation to patchy habitats. These findings not only provided insights into the population dynamics of common reed in changing environments, but also demonstrated the feasibility of using habitat patches in a mosaic landscape as test systems to identify appropriate genetic sources for ecological restoration.

Optimal location of dry ports in the Pan-Pearl River Delta

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Wu Qitao

2017-01-01

Full Text Available Dry ports have become a very important part of globalization and a cornerstone in port competitiveness. Based on the analytic hierarchy process, this paper established the dry port index system to evaluate the potential location of dry ports linked to the port system in the Pearl River Delta, in a case study covering 115 cities in the Pan - Pearl River Delta. The results show that it is optimal to locate 21 dry ports in the research region, and each dry port serves different areas. There are 4 optimal transport corridors for the dry port logistic network, including Guangzhou- Kunming transport corridor, Guangzhou-Chengdu transport corridor, Guangzhou-Changsha transport corridor and Shenzhen-Nanchang transport corridor.

Losses of Sacramento River Chinook Salmon and Delta Smelt to Entrainment in Water Diversions in the Sacramento–San Joaquin Delta

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Wim J. Kimmerer

2008-06-01

Full Text Available Pumping at the water export facilities in the southern Sacramento-San Joaquin Delta kills fish at and near the associated fish-salvage facilities. Correlative analyses of salvage counts with population indices have failed to provide quantitative estimates of the magnitude of this mortality. I estimated the proportional losses of Sacramento River Chinook salmon (Oncorhynchus tshawytscha and delta smelt (Hypomesus transpacificus to place these losses in a population context. The estimate for salmon was based on recoveries of tagged smolts released in the upper Sacramento River basin, and recovered at the fish-salvage facilities in the south Delta and in a trawling program in the western Delta. The proportion of fish salvaged increased with export flow, with a mean value around 10% at the highest export flows recorded. Mortality was around 10% if pre-salvage losses were about 80%, but this value is nearly unconstrained. Losses of adult delta smelt in winter and young delta smelt in spring were estimated from salvage data (adults corrected for estimated pre-salvage survival, or from trawl data in the southern Delta (young. These losses were divided by population size and accumulated over the respective seasons. Losses of adult delta smelt were 1–50% (median 15% although the highest value may have been biased upward. Daily losses of larvae and juveniles were 0–8%, and seasonal losses accumulated were 0–25% (median 13%. The effect of these losses on population abundance was obscured by subsequent 50-fold variability in survival from summer to fall.

Carbon Stocks in Permafrost-Affected Soils of the Lena River Delta

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Zubrzycki, S.; Kutzbach, L.; Grosse, G.; Desyatkin, A.; Pfeiffer, E.

2012-12-01

The soil organic carbon stock (SSOC) of soils in arctic permafrost regions is known to be significant but is insufficiently investigated so far. Previous SSOC studies report mainly the gravimetric carbon (C) contents and are limited to the active layer depth at the time of sampling. Since C deposits in permafrost regions are likely to become a future C source, more detailed investigations of the presently frozen likely carbon-rich sediment and soil layers are of importance. Our investigations were performed on Samoylov Island in the southern-central part of the Lena River Delta (32,000 km2) which is the largest arctic delta and the fifth largest delta worldwide. Samoylov Island is representative for the Lena River Delta's first terrace and the active floodplains. Within this study a new portable Snow-Ice-Permafrost-Research-Establishment (SIPRE) auger was used during a spring field session to obtain 1 m deep frozen soil cores (n = 29) distributed over all known soil and vegetation units. These cores are analyzed for bulk contents of nitrogen (N) and C, ice content and bulk density (BD) and to determine the SSOC including the rarely investigated currently permanently frozen layers up to 1 m depth on Samoylov Island. Our study provides evidence for high SSOC for a depth of 1 m for the investigated area ranging between 7 kg m-2 and 48 kg m-2. Considering the spatial extent of different soil units on the two geomorphological units of Samoylov Island, the area-weighted average SSOC were 29 kg m-2 (n = 22) for the first terrace and 14 kg m-2 (n = 7) for the active floodplain. For the correspondent soil units of Turbels and Orthels in circumpolar permafrost regions a mean SSOC of 27 kg m-2 (min: 0.1 kg m-2, max: 126 kg m-2) for a depth of 1 m was reported [1]. For up-scaling solely over the soil-covered areas of the Lena River Delta, we excluded all water bodies >3,600 m2 from the geomorphological units studied (first river terrace and the active floodplains) and

Suitability of pharmaceuticals and personal care products (PPCPs) and artificial sweeteners (ASs) as wastewater indicators in the Pearl River Delta, South China.

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Yang, Yuan-Yuan; Liu, Wang-Rong; Liu, You-Sheng; Zhao, Jian-Liang; Zhang, Qian-Qian; Zhang, Min; Zhang, Jin-Na; Jiang, Yu-Xia; Zhang, Li-Juan; Ying, Guang-Guo

2017-07-15

Wastewater indicator is a useful tool for evaluating the wastewater impact on natural water, but there is little information about the suitability of wastewater indicators for different regions. This study aimed to select suitable wastewater indicators in the Pearl River Delta region, south China by screening a range of wastewater related organic compounds. The screening campaign was carried out by investigating the occurrence and removal efficiencies of 93 pharmaceuticals and personal care products (PPCPs) and 5 artificial sweeteners (ASs) in nine wastewater treatment plants (WWTPs) located in the region, and the occurrence of these target compounds in the contaminated and clean surface water of the Pearl River. An ideal wastewater indicator should be hydrophilic, source-specific for domestic wastewater, ubiquitous in contaminated surface water with detection frequency (DF) >80% and absent in background water samples. For liable indicators, high removal rates (>90%) should be observed in WWTPs and they should be detected in all the influent samples at concentrations fifty times higher than their limits of quantification. For conservative indicators, low removal rates (<50%) should be observed in WWTPs and they should be detected in all the effluent samples at concentrations fifty times higher than their limits of quantification. Based on the above criteria, sucralose and fluconazole were selected as conservative indicators in the region, while cyclamate, saccharin, methyl paraben, ethyl paraben, propyl paraben, paracetamol, salicylic acid and caffeine were selected as liable indicators. Copyright © 2017 Elsevier B.V. All rights reserved.

Accumulation, transfer, and environmental risk of soil mercury in a rapidly industrializing region of the Yangtze River Delta, China

Energy Technology Data Exchange (ETDEWEB)

Huang, Biao; Yan, Lianxiang; Sun, Weixia; Zhao, Yongcun; Shi, Xuezheng [Chinese Academy of Sciences, Nanjing (China). State Key Lab. of Soil and Sustainable Agriculture; Wang, Mei [Chinese Academy of Sciences, Nanjing (China). State Key Lab. of Soil and Sustainable Agriculture; Graduate Univ. of the Chinese Academy of Sciences, Beijing (China); Weindorf, David C. [Louisiana State Univ., Baton Rouge, LA (United States). AgCenter

2011-06-15

Purpose: Mercury (Hg) accumulation and transfer in soil ecosystems has been altered on local, regional, and even global scales, and their environmental risk has increasingly been a concern to the public and the scientific community. Materials and methods: A county level region in Zhangjiagang County, the Yangtze River Delta (YRD) region of China and a factory with Hg-contaminated wastewater discharging within the region were selected to study the accumulation, bioavailability, and transfer of Hg from different sources in soils and crops under rapid industrialization, urbanization, and intensive agricultural activities. Regional soil samples close to and away from factories and local soil and crop samples around a typical factory were collected in the YRD region of China. Soil and crop Hg and basic soil properties were examined. Results and discussion: Significant soil Hg accumulation was found in soils away from factories regardless of Cambosols (Entisols) and Anthrosols (Inceptisols), while the mobile HCl-extractable Hg (HCl-Hg) were greater in soils closer to factories due to a decrease and increase in soil pH and organic matter. A high level of soil total Hg (T-Hg) was found around the factory, and soil and crop Hg accumulation in the vicinity of the factory was localized with an exponential decrease as distance away from the wastewater discharge outlet increased. Although Hg accumulated in these soils, the T-Hg levels at only a few sampling sites in acidic Anthrosols area were found to exceed the second most stringent critical value of Chinese Environmental Quality Standards for Soils. Conclusions: Considering the cessation of Hg-containing agrochemicals and limitation of effects of industrial activities on Hg accumulation, more attention should be paid to the changes in soil properties and crop rotations than controlling the pathways of Hg entering soils because the current environmental risk is mobilization of accumulated soil Hg. (orig.)

Influence of synoptic condition and holiday effects on VOCs and ozone production in the Yangtze River Delta region, China

Science.gov (United States)

Xu, Zhengning; Huang, Xin; Nie, Wei; Chi, Xuguang; Xu, Zheng; Zheng, Longfei; Sun, Peng; Ding, Aijun

2017-11-01

Both anthropogenic emission and synoptic conditions play important roles in ozone (O3) formation and accumulation. In order to understand the influence of synoptic condition and holiday effects on ozone production in the Yangtze River Delta region, China, concentrations of speciated volatile organic compounds (VOCs) and O3 as well as other relevant trace gases were simultaneously measured at the Station for Observing Regional Processes of the Earth System (SORPES) in Nanjing around the National Day holidays of China in 2014, which featured substantial change of emissions and dominated by typical anti-cyclones. Different groups of VOC species and their chemical reactivities were comprehensively analyzed. We observed clear diurnal variations of short alkenes during the measurement period, considerable amount of short alkenes were observed during night (more than 10 ppb) while almost no alkenes were measured during daytime, which might be attributed to different chemical processes. The obvious enhancement of the VOC tracers during the National Day holidays (Oct. 1st-Oct. 7th) indicated that the holiday effect strongly influenced the distribution of VOC profile and chemical reactivity in the atmosphere. At the same time, two meso-scale anticyclone processes were also observed during the measurement period. The synoptic condition contributed to the accumulation of VOCs and other precursors, which consequently impacted the ozone production in this region. The integrated influence of synoptic and holiday effects was also analyzed with an Observation Based Model (OBM) based on simplified MCM (Master Chemical Mechanism) chemical mechanism. The calculated relative increment reactivity (RIR) of different VOC groups revealed that during the holidays, this region was in VOC-limited regime and the variation of RIR shows a close linkage to the development and elimination of anti-cyclones, indicating an in-negligible contribution of synoptic effect toward ozone production in this

Fate of polybrominated diphenyl ethers in the environment of the Pearl River Estuary, South China

International Nuclear Information System (INIS)

Guan Yufeng; Sojinu, O.S. Samuel; Li Shaomeng; Zeng, Eddy Y.

2009-01-01

Ninety-six riverine runoff samples collected at eight major outlets in the Pearl River Delta (PRD), South China, during 2005-2006 were analyzed for 17 brominated diphenyl ether (BDE) congeners (defined as Σ 17 PBDE). Fourteen and 15 congeners were detected, respectively, in the dissolved and particulate phases. These data were further used to elucidate the partitioning behavior of BDE congeners in riverine runoff. Several related fate processes, i.e. air-water exchange, dry and wet deposition, degradation, and sedimentation, within the Pearl River Estuary (PRE), were examined to estimate the inputs of Σ 10 PBDE (sum of the target BDE congeners, BDE-28, -47, -66, -85, -99, -100, -138, -153, -154, and -183) and BDE-209 from the PRD to the coastal ocean based on mass balance considerations. The results showed that annual outflows of Σ 10 PBDE and BDE-209 were estimated at 126 and 940 kg/year, respectively from the PRE to coastal ocean. Besides sedimentation and degradation, the majority of Σ 10 PBDE and BDE-209 discharged into the PRE via riverine runoff was transported to the coastal ocean. - Fate of polybrominated diphenyl ethers in the environment the Pearl River Estuary, South China.

Source apportionment of fine particles and its chemical components over the Yangtze River Delta, China during a heavy haze pollution episode

Science.gov (United States)

Li, L.; An, J. Y.; Zhou, M.; Yan, R. S.; Huang, C.; Lu, Q.; Lin, L.; Wang, Y. J.; Tao, S. K.; Qiao, L. P.; Zhu, S. H.; Chen, C. H.

2015-12-01

An extremely high PM2.5 pollution episode occurred over the eastern China in January 2013. In this paper, the particulate matter source apportionment technology (PSAT) method coupled within the Comprehensive air quality model with extensions (CAMx) is applied to study the source contributions to PM2.5 and its major components at six receptors (Urban Shanghai, Chongming, Dianshan Lake, Urban Suzhou, Hangzhou and Zhoushan) in the Yangtze River Delta (YRD) region. Contributions from 4 source areas (including Shanghai, South Jiangsu, North Zhejiang and Super-region) and 9 emission sectors (including power plants, industrial boilers and kilns, industrial processing, mobile source, residential, volatile emissions, dust, agriculture and biogenic emissions) to PM2.5 and its major components (sulfate, nitrate, ammonia, organic carbon and elemental carbon) at the six receptors in the YRD region are quantified. Results show that accumulation of local pollution was the largest contributor during this air pollution episode in urban Shanghai (55%) and Suzhou (46%), followed by long-range transport (37% contribution to Shanghai and 44% to Suzhou). Super-regional emissions play an important role in PM2.5 formation at Hangzhou (48%) and Zhoushan site (68%). Among the emission sectors contributing to the high pollution episode, the major source categories include industrial processing (with contributions ranging between 12.7 and 38.7% at different receptors), combustion source (21.7-37.3%), mobile source (7.5-17.7%) and fugitive dust (8.4-27.3%). Agricultural contribution is also very significant at Zhoushan site (24.5%). In terms of the PM2.5 major components, it is found that industrial boilers and kilns are the major source contributor to sulfate and nitrate. Volatile emission source and agriculture are the major contributors to ammonia; transport is the largest contributor to elemental carbon. Industrial processing, volatile emissions and mobile source are the most significant

Magnitude of arsenic pollution in the Mekong and Red River Deltas - Cambodia and Vietnam

International Nuclear Information System (INIS)

Berg, Michael; Stengel, Caroline; Trang, Pham Thi Kim; Hung Viet, Pham; Sampson, Mickey L.; Leng, Moniphea; Samreth, Sopheap; Fredericks, David

2007-01-01

Large alluvial deltas of the Mekong River in southern Vietnam and Cambodia and the Red River in northern Vietnam have groundwaters that are exploited for drinking water by private tube-wells, which are of increasing demand since the mid-1990s. This paper presents an overview of groundwater arsenic pollution in the Mekong delta: arsenic concentrations ranged from 1-1610 μg/L in Cambodia (average 217 μg/L) and 1-845 μg/L in southern Vietnam (average 39 μg/L), respectively. It also evaluates the situation in Red River delta where groundwater arsenic concentrations vary from 1-3050 μg/L (average 159 μg/L). In addition to rural areas, the drinking water supply of the city of Hanoi has elevated arsenic concentrations. The sediments of 12-40 m deep cores from the Red River delta contain arsenic levels of 2-33 μg/g (average 7 μg/g, dry weight) and show a remarkable correlation with sediment-bound iron. In all three areas, the groundwater arsenic pollution seem to be of natural origin and caused by reductive dissolution of arsenic-bearing iron phases buried in aquifers. The population at risk of chronic arsenic poisoning is estimated to be 10 million in the Red River delta and 0.5-1 million in the Mekong delta. A subset of hair samples collected in Vietnam and Cambodia from residents drinking groundwater with arsenic levels > 50 μg/L have a significantly higher arsenic content than control groups (< 50 μg/L). Few cases of arsenic related health problems are recognized in the study areas compared to Bangladesh and West Bengal. This difference probably relates to arsenic contaminated tube-well water only being used substantially over the past 7 to 10 years in Vietnam and Cambodia. Because symptoms of chronic arsenic poisoning usually take more than 10 years to develop, the number of future arsenic related ailments in Cambodia and Vietnam is likely to increase. Early mitigation measures should be a high priority

Experimental investigation of channel avulsion frequency on river deltas under rising sea levels

Science.gov (United States)

Silvestre, J.; Chadwick, A. J.; Steele, S.; Lamb, M. P.

2017-12-01

River deltas are low-relief landscapes that are socioeconomically important; they are home to over half a billion people worldwide. Many deltas are built by cycles of lobe growth punctuated by abrupt channel shifts, or avulsions, which often reoccur at a similar location and with a regular frequency. Previous experimental work has investigated the effect of hydrodynamic backwater in controlling channel avulsion location and timing on deltas under constant sea level conditions, but it is unclear how sea-level rise impacts avulsion dynamics. We present results from a flume experiment designed to isolate the role of relative sea-level rise on the evolution of a backwater-influenced delta. The experiment was conducted in the river-ocean facility at Caltech, where a 7m long, 14cm wide alluvial river drains into a 6m by 3m "ocean" basin. The experimental delta grew under subcritical flow, a persistent backwater zone, and a range of sea level rise rates. Without sea level rise, lobe progradation produced in-channel aggradation and periodic avulsions every 3.6 ± 0.9 hours, which corresponded to when channels aggraded to approximately one-half of their flow depth. With a modest rate of sea-level rise (0.25 mm/hr), we observed enhanced aggradation in the backwater zone, causing channels to aggrade more quickly and avulse more frequently (every 2.1 ± 0.6 hours). In future work, we expect further increases in the rate of relative sea-level rise to cause avulsion frequency to decrease as the delta drowns and the backwater zone retreats upstream. Experimental results can serve as tests of numerical models that are needed for hazard mitigation and coastal sustainability efforts on drowning deltas.

Polybrominated diphenyl ethers in surface sediments of the Yangtze River Delta: Levels, distribution and potential hydrodynamic influence

International Nuclear Information System (INIS)

Chen Shejun; Gao Xiaojiang; Mai Bixian; Chen Zhuomin; Luo Xiaojun; Sheng Guoying; Fu Jiamo; Zeng, Eddy Y.

2006-01-01

A total of 32 surface sediments collected from the Yangtze River Estuary, Hangzhou Bay and the Qiantang River were analyzed for polybrominated diphenyl ethers (PBDEs). The concentrations of ΣPBDEs (sum of 12 PBDE congeners without BDE 209) and BDE 209 varied from n.d. to 0.55 and from 0.16 to 94.6 ng/g, respectively. The spatial variability of ΣPBDEs concentrations indicated that waste discharge from the urban areas might been the main source of PBDEs in the Yangtze River Delta. BDE 209 was the predominant congener (∼90-100%) detected among the 13 congeners, consistent with the fact that technical deca-BDE mixtures are presently the dominant technical PBDE mixtures used in China. Compared to published data acquired from other locales, PBDE congeners with less than four bromines were more abundant in the present study area. The hydrodynamic conditions may likely be a significant factor in dictating the observed levels and congener distribution patterns of PBDEs. - This study discussed the possible effects of hydrodynamic conditions on the distribution of PBDEs in estuarine and marine boundary

A brief history and summary of the effects of river engineering and dams on the Mississippi River system and delta

Science.gov (United States)

Alexander, Jason S.; Wilson, Richard C.; Green, W. Reed

2012-01-01

The U.S. Geological Survey Forecast Mekong project is providing technical assistance and information to aid management decisions and build science capacity of institutions in the Mekong River Basin. A component of this effort is to produce a synthesis of the effects of dams and other engineering structures on large-river hydrology, sediment transport, geomorphology, ecology, water quality, and deltaic systems. The Mississippi River Basin (MRB) of the United States was used as the backdrop and context for this synthesis because it is a continental scale river system with a total annual water discharge proportional to the Mekong River, has been highly engineered over the past two centuries, and the effects of engineering have been widely studied and documented by scientists and engineers. The MRB is controlled and regulated by dams and river-engineering structures. These modifications have resulted in multiple benefits including navigation, flood control, hydropower, bank stabilization, and recreation. Dams and other river-engineering structures in the MRB have afforded the United States substantial socioeconomic benefits; however, these benefits also have transformed the hydrologic, sediment transport, geomorphic, water-quality, and ecologic characteristics of the river and its delta. Large dams on the middle Missouri River have substantially reduced the magnitude of peak floods, increased base discharges, and reduced the overall variability of intraannual discharges. The extensive system of levees and wing dikes throughout the MRB, although providing protection from intermediate magnitude floods, have reduced overall channel capacity and increased flood stage by up to 4 meters for higher magnitude floods. Prior to major river engineering, the estimated average annual sediment yield of the Mississippi River Basin was approximately 400 million metric tons. The construction of large main-channel reservoirs on the Missouri and Arkansas Rivers, sedimentation in dike

Industrial sector-based volatile organic compound (VOC) source profiles measured in manufacturing facilities in the Pearl River Delta, China.

Science.gov (United States)

Zheng, Junyu; Yu, Yufan; Mo, Ziwei; Zhang, Zhou; Wang, Xinming; Yin, Shasha; Peng, Kang; Yang, Yang; Feng, Xiaoqiong; Cai, Huihua

2013-07-01

Industrial sector-based VOC source profiles are reported for the Pearl River Delta (PRD) region, China, based source samples (stack emissions and fugitive emissions) analyzed from sources operating under normal conditions. The industrial sectors considered are printing (letterpress, offset and gravure printing processes), wood furniture coating, shoemaking, paint manufacturing and metal surface coating. More than 250 VOC species were detected following US EPA methods TO-14 and TO-15. The results indicated that benzene and toluene were the major species associated with letterpress printing, while ethyl acetate and isopropyl alcohol were the most abundant compounds of other two printing processes. Acetone and 2-butanone were the major species observed in the shoemaking sector. The source profile patterns were found to be similar for the paint manufacturing, wood furniture coating, and metal surface coating sectors, with aromatics being the most abundant group and oxygenated VOCs (OVOCs) as the second largest contributor in the profiles. While OVOCs were one of the most significant VOC groups detected in these five industrial sectors in the PRD region, they have not been reported in most other source profile studies. Such comparisons with other studies show that there are differences in source profiles for different regions or countries, indicating the importance of developing local source profiles. Crown Copyright © 2013. Published by Elsevier B.V. All rights reserved.

Spatiotemporal variability of biogenic terpenoid emissions in Pearl River Delta, China, with high-resolution land-cover and meteorological data

Science.gov (United States)

Wang, Xuemei; Situ, Shuping; Guenther, Alex; Chen, Fei; Wu, Zhiyong; Xia, Beicheng; Wang, Tijian

2011-04-01

This study intended to provide 4-km gridded, hourly, year-long, regional estimates of terpenoid emissions in the Pearl River Delta (PRD), China. It combined Thematic Mapper images and local-survey data to characterize plant functional types, and used observed emission potential of biogenic volatile organic compounds (BVOC) from local plant species and high-resolution meteorological outputs from the MM5 model to constrain the MEGAN BVOC-emission model. The estimated annual emissions for isoprene, monoterpene and sesquiterpene are 95.55 × 106 kg C, 117.35 × 106 kg C and 9.77 × 106 kg C, respectively. The results show strong variabilities of terpenoid emissions spanning diurnal and seasonal time scales, which are mainly distributed in the remote areas (with more vegetation and less economic development) in PRD. Using MODIS PFTs data reduced terpenoid emissions by 27% in remote areas. Using MEGAN-model default emission factors led to a 24% increase in BVOC emission. The model errors of temperature and radiation in MM5 output were used to assess impacts of uncertainties in meteorological forcing on emissions: increasing (decreasing) temperature and downward shortwave radiation produces more (less) terpenoid emissions for July and January. Strong temporal variability of terpenoid emissions leads to enhanced ozone formation during midday in rural areas where the anthropogenic VOC emissions are limited.

Implementing Integrated River Basin Management in China

NARCIS (Netherlands)

Boekhorst, D.G.J. te; Smits, A.J.M.; Yu, X.; Lifeng, L.; Lei, G.; Zhang, C.

2010-01-01

This paper examines the role of the World Wildlife Fund for Nature China as policy entrepreneur in China. It illustrates the ways in which the World Wildlife Fund for Nature is active in promoting integrated river basin management in the Yangtze River basin and how the efforts at basin level are

Sediment record of polycyclic aromatic hydrocarbons in the Liaohe River Delta wetland, Northeast China: Implications for regional population migration and economic development.

Science.gov (United States)

Ma, Chuanliang; Lin, Tian; Ye, Siyuan; Ding, Xigui; Li, Yuanyuan; Guo, Zhigang

2017-03-01

The polycyclic aromatic hydrocarbons (PAHs) of a 210 Pb-dated sediment core extracted from the Liaohe River Delta wetland were measured to reconstruct the sediment record of PAHs and its response to human activity for the past 300 years in Northeast China. The concentrations of the 16 U.S. Environmental Protection Agency priority PAHs (∑16PAHs) ranged from 46 to 1167 ng g -1 in this sediment core. The concentrations of the 16 PAHs (especially 4- and 5+6-ring PAHs) after the 1980s (surface sediments 0-6 cm) were one or two orders of magnitudes higher than those of the down-core samples. The exponential growth of 4-ring and 5+6-ring PAH concentrations after the 1980s responded well to the increased energy consumption and number of civil vehicles resulting from the rapid economic development in China. Prior to 1950, relatively low levels of the 16 PAHs and a high proportion of 2+3-ring PAHs was indicative of biomass burning as the main source of the PAHs. A significant increase in the 2 + 3 ring PAH concentration from the 1860s-1920s was observed and could be attributed to a constant influx of population migration into Northeast China. It was suggested that the link between historical trend of PAHs and population or energy use involves two different economic stages. Typically, in an agricultural economy, the greater the population size, the greater the emission of PAHs from biomass burning, while in an industrial economy, the increase in sedimentary PAH concentrations is closely related to increasing energy consumption of fossil fuels. Copyright © 2016 Elsevier Ltd. All rights reserved.

Comparing the urbanization and global warming impacts on extreme rainfall characteristics in Southern China Pearl River Delta megacity based on dynamical downscaling

Science.gov (United States)

Fung, K. Y.; Tam, C. Y.; Wang, Z.

2017-12-01

It is well known that urban land use can significantly influence the local temperature, precipitation and meteorology through altering land-atmosphere exchange of momentum, moisture and heat in urban areas. In recent decades, there has been a substantial increase ( 5-10%) on the intensity of extreme rainfall over Southeast China; it is projected to increase further according to the latest IPCC reports. In this study, we assess how urbanization and global warming together might impact on heavy precipitation characteristics over the highly urbanized Pearl River Delta (PRD) megacity, located in southern China. This is done by dynamically downscaling GFDL-ESM2M simulations for the present and future (RCP8.5) climate scenarios, using the Weather Research and Forecasting (WRF) model coupled with a single-layer urban canopy model (UCM). Over the PRD area, the WRF model is integrated at a resolution of 2km x 2km. To focus on extreme events, episodes covering daily rainfall intensity above the 99th percentile in Southeast China in the GFDL-ESM2M daily precipitation datasets were first identified. These extreme episodes were then dynamically downscaled in two parallel experiments with the following model designs: one with anthropogenic heat flux (AH) = 0 Wm-2 and the other with peak AH = 300 Wm-2 in the AH diurnal cycle over the urban domain. Results show that, with AH in urban area, the urban 2m-temperature can rise by about 2oC. This in turn leads to an increase of the mean as well as the extreme rain rates by 10-15% in urban domain. The latter is comparable to the impact of global warming alone, according to downscaling experiments for the RCP8.5 scenario. Implications of our results on urban effects on extreme rainfall under a warming background climate will be discussed.

Concentration and source identification of polycyclic aromatic hydrocarbons and phthalic acid esters in the surface water of the Yangtze River Delta, China

Institute of Scientific and Technical Information of China (English)

Lifei Zhang; Liang Dong; Lijun Ren; Shuangxin Shi; Li Zhou; Ting Zhang; Yeru Huang

2012-01-01

The pollution from polycyclic aromatic hydrocarbons (PAHs) and phthalic acid esters (PAEs) in the surface water of the rapidly urbanized Yangtze River Delta region was investigated.Fourteen surface water samples were collected in June 2010.Water samples were liquid-liquid extracted using methylene chloride and analyzed by gas chromatography-mass spectrometry.Concentrations of PAHs and PAEs ranged 12.9-638.1 ng/L and 61-28550 ng/L,respectively.Fluoranthene,naphthalene,pyrene,phenanthrene,di-2-ethylhexyl phthalate,and di-n-butyl phthalate were the most abundant compounds in the samples.The water samples were moderately Polluted with benzo[a]pyrene according to China's environmental quality standard for surface water.The two highest concentrations of PAHs and PAEs occurred in samples from Taihu Lake,Wuxi City and the western section of Yangchenghu Lake.Potential sources of Pollution at S7 were petroleum combustion and the plastics industry,and at Yangchenghu Lake were petroleum combustion and domestic waste.Pollution in samples from the Beijing-Hangzhou Grand Canal originated from diesel engines.There were no obvious sources of pollution for the other water samples.These results can be used as reference levels for future monitoring programs of pollution from PAHs and PAEs.

The feeding ecology of schilbeid catfishes in river Ase, Niger delta ...

African Journals Online (AJOL)

The feeding ecology of schilbeid catfishes in river Ase, Niger delta, Southern Nigeria. ... Open Access DOWNLOAD FULL TEXT ... in feeding intensity were described for Eutropius niloticus and Schilbe mystus which had adequate data.

Trends and driving mechanism of land-use change in metropolitan areas of Pearl River Delta

Science.gov (United States)

Chen, Feng-gui; Zhang, Hong-ou; Wang, Juan; Wu, Qi-tao

2008-10-01

Taking Pearl River Delta for an example this study focuses on the trends and the driving mechanism of land-use changes in metropolises, in order to achieve the fundamental objectives of LUCC study increasing the awareness on dynamics of global land-use and land-cover changes, and improving the ability of forecasting LUCC. By analyzing the land-use change in Pearl River Delta from 1996 to 2006, it is found that the differences among internal space are notable. By establishing time-sequence-curve with SPSS software, it is shown that trends of land-use change are very clear. With factor analysis on land-use change, the study summarizes four factors of driving mechanism, including factors of economic development level, regional industrial structure, demographic and agricultural structure adjustment, which impact land change in Pearl River Delta to a different extent.

Monitoring and modeling land-use change in the Pearl River Delta, China, using satellite imagery and socioeconomic data

Science.gov (United States)

Seto, Karen Ching-Yee

Over the last two decades, rapid rates of economic growth in the People's Republic of China have converted large areas of natural ecosystems and agricultural lands to urban uses. The size and rate of these land-use changes may affect local and regional climate, biogeochemistry, and food supply. To assess these impacts, both the amount of land converted and its relation to socioeconomic drivers must be determined. This research combines satellite remote sensing, which is used to monitor land conversion, with socioeconomic data to model the economic and demographic drivers of land-use change in the Pearl River Delta of Southern China. This research modifies existing techniques and develops new methods to assess the type, amount, and timing of land-use change from annual Landsat Thematic Mapper (TM) images from 1988 to 1996. During this period, most of the land-use change is conversion of agricultural land to urban areas. Results indicate that urban areas, increased by over 300% between 1988 and 1996. Field assessments confirm these results and indicate that the land-use change map is highly accurate at 93.5%. To use these data as inputs to statistical models, the year of land conversion derived from satellite imagery must be unbiased. A new method that uses time series techniques identifies the date at which land-use changes occur from a sequential series of TM images. The accuracy and bias of the dates of change identified compare favorably to a more conventional remote sensing change detection technique and may have the additional advantages of reducing efforts required to assemble training data and to correct for atmospheric effects. Data on the quantity of land-use change and the timing of these changes are used in conjunction with socioeconomic data to estimate statistical models that identify and quantify the demographic and economic changes on two types of land conversion: urbanization of agricultural land and urbanization of natural vegetation. Results

Effects of elevated O3 exposure on nutrient elements and quality of winter wheat and rice grain in Yangtze River Delta, China

International Nuclear Information System (INIS)

Zheng, Feixiang; Wang, Xiaoke; Zhang, Weiwei; Hou, Peiqiang; Lu, Fei; Du, Keming; Sun, Zhongfu

2013-01-01

With the open-top chambers (OTCs) in situ in Yangtze River Delta, China in 2007 and 2008, the effects of elevated O 3 exposure on nutrient elements and quality of winter wheat and rice grain were investigated. Grain yield per plant of winter wheat and rice declined in both years. The N and S concentrations increased under elevated O 3 exposure in both years and C–N ratios decreased significantly. The concentrations of K, Ca, Mg, P, Mn, Cu and Zn in winter wheat and the concentrations of Mg, K, Mn and Cu in rice increased. The concentrations of protein, amino acid and lysine in winter wheat and rice increased and the concentration of amylose decreased. The increase in the nutrient concentration was less than the reduction of grain yield in both winter wheat and rice, and, hence, the absolute amount of the nutrients was reduced by elevated O 3 . -- Highlights: •The nutrient elements and quality of winter wheat and rice grain response to ozone had been investigated for two years in China. •Grain yield per plant of winter wheat and rice were reduced in both years. •The extent of ozone impact on the nutrient elements concentrations of winter wheat and rice were different. •The concentrations of protein, amino acid and lysine increased but the concentrations of amylose decreased. •The absolute amount of the nutrients was reduced by elevated O 3 . -- The nutrient elements and quality of winter wheat and rice grain were seriously affected under the elevated O 3 exposure

Retrieval of High-Resolution Atmospheric Particulate Matter Concentrations from Satellite-Based Aerosol Optical Thickness over the Pearl River Delta Area, China

Directory of Open Access Journals (Sweden)

Lili Li

2015-06-01

Full Text Available Satellite remote sensing offers an effective approach to estimate indicators of air quality on a large scale. It is critically significant for air quality monitoring in areas experiencing rapid urbanization and consequently severe air pollution, like the Pearl River Delta (PRD in China. This paper starts with examining ground observations of particulate matter (PM and the relationship between PM10 (particles smaller than 10 μm and aerosol optical thickness (AOT by analyzing observations on the sampling sites in the PRD. A linear regression (R2 = 0.51 is carried out using MODIS-derived 500 m-resolution AOT and PM10 concentration from monitoring stations. Data of atmospheric boundary layer (ABL height and relative humidity are used to make vertical and humidity corrections on AOT. Results after correction show higher correlations (R2 = 0.55 between extinction coefficient and PM10. However, coarse spatial resolution of meteorological data affects the smoothness of retrieved maps, which suggests high-resolution and accurate meteorological data are critical to increase retrieval accuracy of PM. Finally, the model provides the spatial distribution maps of instantaneous and yearly average PM10 over the PRD. It is proved that observed PM10 is more relevant to yearly mean AOT than instantaneous values.

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

Science.gov (United States)

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

Mercury profiles in sediments of the Pearl River Estuary and the surrounding coastal area of South China

International Nuclear Information System (INIS)

Shi Jianbo; Ip, Carman C.M.; Zhang Gan; Jiang Guibin; Li Xiangdong

2010-01-01

The spatial and temporal variations of mercury (Hg) in sediments of the Pearl River Estuary (PRE) and the surrounding coastal area (South China Sea) were studied. In surface sediments, the concentrations of Hg ranged from 1.5 to 201 ng/g, with an average of 54.4 ng/g, displaying a decreasing trend with the distance from the estuary to the open sea. This pattern indicates that the anthropogenic emissions from the Pearl River Delta (PRD) region are probably the main sources of Hg in this coastal region. Using the 210 Pb dating technique, the historical changes in the concentrations and influxes of Hg in the last 100 years were also investigated. The variations in Hg influxes in sediment cores obviously correlate with the economic development and urbanization that has occurred the PRD region, especially in the last three decades. - The spatial and historical changes of Hg in sediment reflect the industrial development and urbanization of the region in south China.

Dendroclimatology of the Slave River Delta, Northwest Territories, Canada

Science.gov (United States)

Jarvis, S.; Buhay, W. M.; Blair, D.; Tardif, J.; Bailey, D.

2004-05-01

It is well documented that changing hydrological conditions impact delta ecosystems. Such changes can also affect local inhabitants who have historical connections to the area and its resources. During the summer of 2003 a multifaceted paleo-environmental project was initiated to reconstruct the frequencies of floods and droughts in the Slave River Delta (SRD), Northwest Territories, Canada. The project goal is to forecast future hydrological and ecological conditions in the SRD in light of anticipated climate change and increasing demand on water resources. With the intent of expanding the climate history of the SRD, this particular aspect of the project will employ white spruce tree-ring chronologies constructed from six sites visited within the delta. Work is currently in progress to build a master chronology estimated to span over 300 years. In addition, a climate model for the SRD is also being developed and will be highlighted.

Stepwise morphological evolution of the active Yellow River (Huanghe) delta lobe (1976-2013): Dominant roles of riverine discharge and sediment grain size

Science.gov (United States)

Wu, Xiao; Bi, Naishuang; Xu, Jingping; Nittrouer, Jeffrey A.; Yang, Zuosheng; Saito, Yoshiki; Wang, Houjie

2017-09-01

The presently active Yellow River (Huanghe) delta lobe has been formed since 1976 when the river was artificially diverted. The process and driving forces of morphological evolution of the present delta lobe still remain unclear. Here we examined the stepwise morphological evolution of the active Yellow River delta lobe including both the subaerial and the subaqueous components, and illustrated the critical roles of riverine discharge and sediment grain size in dominating the deltaic evolution. The critical sediment loads for maintaining the delta stability were also calculated from water discharge and sediment load measured at station Lijin, the last gauging station approximately 100 km upstream from the river mouth. The results indicated that the development of active delta lobe including both subaerial and subaqueous components has experienced four sequential stages. During the first stage (1976-1981) after the channel migration, the unchannelized river flow enhanced deposition within the channel and floodplain between Lijin station and the river mouth. Therefore, the critical sediment supply calculated by the river inputs obtained from station Lijin was the highest. However, the actual sediment load at this stage (0.84 Gt/yr) was more than twice of the critical sediment load ( 0.35 Gt/yr) for sustaining the active subaerial area, which favored a rapid seaward progradation of the Yellow River subaerial delta. During the second stage (1981-1996), the engineering-facilitated channelized river flow and the increase in median grain size of suspended sediment delivered to the sea resulted in the critical sediment load for keeping the delta stability deceasing to 0.29 Gt/yr. The active delta lobe still gradually prograded seaward at an accretion rate of 11.9 km2/yr at this stage as the annual sediment load at Lijin station was 0.55 Gt/yr. From 1996 to 2002, the critical sediment load further decreased to 0.15 Gt/yr with the sediment grain size increased to 22.5 �

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

Science.gov (United States)

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

Current levels and composition profiles of PBDEs and alternative flame retardants in surface sediments from the Pearl River Delta, southern China: Comparison with historical data

International Nuclear Information System (INIS)

Chen, She-Jun; Feng, An-Hong; He, Ming-Jing; Chen, Man-Ying; Luo, Xiao-Jun; Mai, Bi-Xian

2013-01-01

Polybrominated diphenyl ethers (PBDEs) and alternative flame retardants were measured in surface sediments collected during 2009–2010 from the Pearl River Delta, southern China (a large manufacturing base for electronics/electrical products), to evaluate the influence of China's RoHS directive (adopted in 2006) on their environmental occurrence. The concentrations in sediments from different water systems ranged from 3.67 to 2520 ng/g (average of 17.1–588 ng/g) for PBDEs and from 0.22 to 5270 ng/g (average of 11.3–454 ng/g) for the alternative retardants. Although the PBDE levels have decreased significantly compared with those in sediments collected in 2002 in this region, the levels of alternative decabromodiphenyl ethane (DBDPE) have exceeded those of BDE209 (two predominant halogenated flame retardants (HFRs) in China) in the majority of sediments. This finding suggests a different contaminant pattern of HFRs in current sediments due to the replacement of the deca-BDE mixture with DBDPE in this region. In addition, sediment concentrations of discontinued PBDEs in the rural area are clearly elevated due to e-waste dismantling. The congener profiles of PBDEs in the current sediments (with more abundant lower-brominated congeners) differed substantially from those in 2002 and from the technical products, suggesting that biological or photolytic debromination of PBDEs may have occurred in the environment. - Highlights: ► PBDE levels in sediments have decreased substantially since China's RoHS directive. ► Contamination of novel DBDPE has exceeded that of deca-BDE in the PRD sediments. ► The congener profiles of PBDEs in the sediments have changed significantly. ► Significant biological or photolytic degradation of PBDEs may occur in the environment

Suspended sediment data analysis: Mackenzie Delta, NWT 1992-93 update [and] Westbank Tributaries, Mackenzie River, NWT

Energy Technology Data Exchange (ETDEWEB)

Carson, M A

1993-03-01

A full analysis and review of sediment data collected in 1991 as part of a program dealing with sediment-related aspects of northern hydrocarbon development is presented. The data were collected at two delta-head stations, three mid-delta stations, and three outer-delta stations. The primary purpose of the program is to obtain mathematical relationships that will allow prediction of sediment concentration at delta stations in the absence of actual sampling. This task is a prerequisite to the development of a sediment adjunct to the one-dimensional hydraulic model being developed for the delta. Preliminary analysis indicates strong correlations between sediment concentrations at different stations in the delta. It is tentatively proposed that sediment concentrations at all east-central stations in the delta could be predicted from samples concentrations at Inuvik, and that concentrations on the west side could be predictable from Peel River Station. The second part of this report deals with suspended sediment data analysis for the westbank tributaries of the Mackenzie River. 19 refs., 36 figs., 29 tabs.

Magnetic Properties of the Rivers Feeding the South China Sea: a Critical Step for Understanding the Paleo-Marine Records.

Science.gov (United States)

Kissel, C.; Liu, Z.; Wandres, C.

2014-12-01

In order to use the magnetic properties of marine sediments as a tracer for past changes in the precipitation rate on land and in oceanic water masses transport and exchanges in the South China Sea, we identify and characterize the different sources of the detrital fraction among which the magnetic particles. This work is presently conducted in the framework of the Franco-Chinese LIA-MONOCL Thanks to the Westpac project, we had access to sediments collected in the deltas of the main rivers feeding the South China Sea from about 25°N to the equator. This is represented on the Asian continent by the Pearl river, the Red River, the Mekong river, by Malaysia, Sumatra and Borneo regions with minor rivers but also contributing to the South China Sea, and finally by Luzon and Taiwan. The geological formations contributing to the river sediment discharges are different from one catchment basin to another as well as the present climatic conditions. The magnetic analyses consist in the analysis of low-field magnetic susceptibility, ARM acquisition and decay, IRM acquisition and decay, back-field acquisition, thermal demagnetization of 3-axes IRM, hysteresis parameters, and FORC diagrams. The obtained parameters all together allow us to define the nature of the magnetic grains and their grain size distribution when magnetite is dominant. Some degree of variability is observed at the river mouths, illustrating different geological sources at the local/regional scale. As an average, it appears that the Southern basin of the South China Sea is surrounded by regions richer in high coercivity magnetic minerals than the northern basin. This mineral is identified as hematite while magnetites (and sulfides) are more abundant in the north. These results are complementary to the clay mineral assemblages previously determined on the same samples. The first steps of a similar study conducted on marine core-tops well distributed in the South China Sea will also be illustrated.

Investigation of carbonyl compound sources at a rural site in the Yangtze River Delta region of China.

Science.gov (United States)

Wang, Ming; Chen, Wentai; Shao, Min; Lu, Sihua; Zeng, Limin; Hu, Min

2015-02-01

Carbonyl compounds are important intermediates in atmospheric photochemistry, but their primary sources are still not understood well. In this work, carbonyls, hydrocarbons, and alkyl nitrates were continuously measured during November 2011 at a rural site in the Yangtze River Delta region of China. Mixing ratios of carbonyls and hydrocarbons showed large fluctuations during the entire measurement. The average level for total measured volatile organic compounds during the pollution episode from 25th to 27th November, 2011 was 91.6 ppb, about 7 times the value for the clean period of 7th-8th, November, 2011. To preliminarily identify toluene sources at this site, the emission ratio of toluene to benzene (T/B) during the pollution episode was determined based on photochemical ages derived from the relationship of alkyl nitrates to their parent alkanes. The calculated T/B was 5.8 ppb/ppb, significantly higher than the values of 0.2-1.7 ppb/ppb for vehicular exhaust and other combustion sources, indicating the dominant influence of industrial emissions on ambient toluene. The contributions of industrial sources to ambient carbonyls were then calculated using a multiple linear regression fit model that used toluene and alkyl nitrates as respective tracers for industrial emission and secondary production. During the pollution episode, 18.5%, 69.0%, and 52.9% of measured formaldehyde, acetaldehyde, and acetone were considered to be attributable to industrial emissions. The emission ratios relative to toluene for formaldehyde, acetaldehyde, and acetone were determined to be 0.10, 0.20 and 0.40 ppb/ppb, respectively. More research on industrial carbonyl emission characteristics is needed to understand carbonyl sources better. Copyright © 2014. Published by Elsevier B.V.

Relationships of relative humidity with PM2.5 and PM10 in the Yangtze River Delta, China.

Science.gov (United States)

Lou, Cairong; Liu, Hongyu; Li, Yufeng; Peng, Yan; Wang, Juan; Dai, Lingjun

2017-10-23

Severe particulate matter (PM, including PM 2.5 and PM 10 ) pollution frequently impacts many cities in the Yangtze River Delta (YRD) in China, which has aroused growing concern. In this study, we examined the associations between relative humidity (RH) and PM pollution using the equal step-size statistical method. Our results revealed that RH had an inverted U-shaped relationship with PM 2.5 concentrations (peaking at RH = 45-70%), and an inverted V-shaped relationship (peaking at RH = 40 ± 5%) with PM 10 , SO 2 , and NO 2 . The trends of polluted-day number significantly changed at RH = 70%. The very-dry (RH humidity (RH = 60-70%) conditions positively affected PM 2.5 and exerted an accumulation effect, while the mid-humidity (RH = 70-80%), high-humidity (RH = 80-90%), and extreme-humidity (RH = 90-100%) conditions played a significant role in reducing particle concentrations. For PM 10 , the accumulation and reduction effects of RH were split at RH = 45%. Moreover, an upward slope in the PM 2.5 /PM 10 ratio indicated that the accumulation effects from increasing RH were more intense on PM 2.5 than on PM 10 , while the opposite was noticed for the reduction effects. Secondary transformations from SO 2 and NO 2 to sulfate and nitrate were mainly responsible for PM 2.5 pollution, and thus, controlling these precursors is effective in mitigating the PM pollution in the YRD, especially during winter. The conclusions in this study will be helpful for regional air-quality management.

[Transport characteristics of air pollutants over the Yangtze Delta].

Science.gov (United States)

Wang, Yan; Chai, Fa-He; Wang, Yong-Hong; Liu, Ming

2008-05-01

Meteorological field of January, April, July and October in 2004 was obtained by running MM5 with NCEP datasets. Then we used HYSPLIT 4.8 model to calculate the backward and forward trajectories of representative cities. Distributions of trajectories and the affected areas vary with seasons. Transport current affecting Yangtze River Delta is mainly from Mongolia, North China or Northeast region, via Yellow Sea area, Shandong, Jiangsu province or Shanghai. Another important transport path is current from southwest because of the Southwest monsoon. A movement of East Asia monsoon plays an important part in the mesoscale transport of pollutants in Yangtze Delta. Winter monsoon is a main mechanism which moves the air pollutants in Yangtze Delta to South China and West Pacific ocean. Another important transport system is the subtropical anticyclone over the western Pacific Ocean which controls the east coast of our country in spring and summer. This circulation system mainly affects the inland area of our country.

Heavy Metal Pollution Delineation Based on Uncertainty in a Coastal Industrial City in the Yangtze River Delta, China

Directory of Open Access Journals (Sweden)

Bifeng Hu

2018-04-01

Full Text Available Assessing heavy metal pollution and delineating pollution are the bases for evaluating pollution and determining a cost-effective remediation plan. Most existing studies are based on the spatial distribution of pollutants but ignore related uncertainty. In this study, eight heavy-metal concentrations (Cr, Pb, Cd, Hg, Zn, Cu, Ni, and Zn were collected at 1040 sampling sites in a coastal industrial city in the Yangtze River Delta, China. The single pollution index (PI and Nemerow integrated pollution index (NIPI were calculated for every surface sample (0–20 cm to assess the degree of heavy metal pollution. Ordinary kriging (OK was used to map the spatial distribution of heavy metals content and NIPI. Then, we delineated composite heavy metal contamination based on the uncertainty produced by indicator kriging (IK. The results showed that mean values of all PIs and NIPIs were at safe levels. Heavy metals were most accumulated in the central portion of the study area. Based on IK, the spatial probability of composite heavy metal pollution was computed. The probability of composite contamination in the central core urban area was highest. A probability of 0.6 was found as the optimum probability threshold to delineate polluted areas from unpolluted areas for integrative heavy metal contamination. Results of pollution delineation based on uncertainty showed the proportion of false negative error areas was 6.34%, while the proportion of false positive error areas was 0.86%. The accuracy of the classification was 92.80%. This indicated the method we developed is a valuable tool for delineating heavy metal pollution.

Heavy Metal Pollution Delineation Based on Uncertainty in a Coastal Industrial City in the Yangtze River Delta, China.

Science.gov (United States)

Hu, Bifeng; Zhao, Ruiying; Chen, Songchao; Zhou, Yue; Jin, Bin; Li, Yan; Shi, Zhou

2018-04-10

Assessing heavy metal pollution and delineating pollution are the bases for evaluating pollution and determining a cost-effective remediation plan. Most existing studies are based on the spatial distribution of pollutants but ignore related uncertainty. In this study, eight heavy-metal concentrations (Cr, Pb, Cd, Hg, Zn, Cu, Ni, and Zn) were collected at 1040 sampling sites in a coastal industrial city in the Yangtze River Delta, China. The single pollution index (PI) and Nemerow integrated pollution index (NIPI) were calculated for every surface sample (0-20 cm) to assess the degree of heavy metal pollution. Ordinary kriging (OK) was used to map the spatial distribution of heavy metals content and NIPI. Then, we delineated composite heavy metal contamination based on the uncertainty produced by indicator kriging (IK). The results showed that mean values of all PIs and NIPIs were at safe levels. Heavy metals were most accumulated in the central portion of the study area. Based on IK, the spatial probability of composite heavy metal pollution was computed. The probability of composite contamination in the central core urban area was highest. A probability of 0.6 was found as the optimum probability threshold to delineate polluted areas from unpolluted areas for integrative heavy metal contamination. Results of pollution delineation based on uncertainty showed the proportion of false negative error areas was 6.34%, while the proportion of false positive error areas was 0.86%. The accuracy of the classification was 92.80%. This indicated the method we developed is a valuable tool for delineating heavy metal pollution.

Heavy Metal Pollution Delineation Based on Uncertainty in a Coastal Industrial City in the Yangtze River Delta, China

Science.gov (United States)

Zhao, Ruiying; Chen, Songchao; Zhou, Yue; Jin, Bin; Li, Yan

2018-01-01

Assessing heavy metal pollution and delineating pollution are the bases for evaluating pollution and determining a cost-effective remediation plan. Most existing studies are based on the spatial distribution of pollutants but ignore related uncertainty. In this study, eight heavy-metal concentrations (Cr, Pb, Cd, Hg, Zn, Cu, Ni, and Zn) were collected at 1040 sampling sites in a coastal industrial city in the Yangtze River Delta, China. The single pollution index (PI) and Nemerow integrated pollution index (NIPI) were calculated for every surface sample (0–20 cm) to assess the degree of heavy metal pollution. Ordinary kriging (OK) was used to map the spatial distribution of heavy metals content and NIPI. Then, we delineated composite heavy metal contamination based on the uncertainty produced by indicator kriging (IK). The results showed that mean values of all PIs and NIPIs were at safe levels. Heavy metals were most accumulated in the central portion of the study area. Based on IK, the spatial probability of composite heavy metal pollution was computed. The probability of composite contamination in the central core urban area was highest. A probability of 0.6 was found as the optimum probability threshold to delineate polluted areas from unpolluted areas for integrative heavy metal contamination. Results of pollution delineation based on uncertainty showed the proportion of false negative error areas was 6.34%, while the proportion of false positive error areas was 0.86%. The accuracy of the classification was 92.80%. This indicated the method we developed is a valuable tool for delineating heavy metal pollution. PMID:29642623

Heavy metal contents and transfer capacities of Phragmites australis and Suaeda salsa in the Yellow River Delta, China

Science.gov (United States)

Zhang, Shuai; Bai, Junhong; Wang, Wei; Huang, Laibing; Zhang, Guangliang; Wang, Dawei

2018-04-01

Plant samples including roots, stems and leaves of Phragmites australis and Suaeda salsa were collected in the short-term flooding and tidal flooding wetlands of the Yellow River Delta of China. Six heavy metals (e.g., As, Cd, Cr, Cu, Pb, and Zn) were measured in roots, stems and leaves of each plant species using inductively coupled plasma atomic absorption spectrometry (ICP-AAS) to investigate the levels, and transfer capabilities of heavy metals in these two plant species. Our results showed that in the tidal flooding wetlands, the contents of As, Cr and Cd in roots of Phragmites australis and Suaeda salsa were higher than those in their stems and leaves. Suaeda salsa showed higher contents of Pb and Zn in leaves than those in roots and stems, whereas lower levels of Pb and Zn were observed in Phragmites australis. In the short-term flooding wetlands, heavy metal contents exhibited a big difference between different tissues of Phragmites australis and Suaeda salsa, and both plant species showed higher levels of Pb and Zn in leaves. Suaeda salsa roots enriched more As and Cd, whereas higher enrichment levels were observed in Phragmites australis leaves, which indicated different transfer capacities of these two wetland plants. The transfer factors for stems and leaves of Phragmites australis in the tidal flooding wetlands significantly differed from those in the short-term flooding wetlands, however, no significant differences in transfer factors for stems and leaves of Suaeda salsa were observed between these two types of wetlands.

Long-term impacts of aerosols on precipitation and lightning over the Pearl River Delta megacity area in China

Directory of Open Access Journals (Sweden)

Y. Wang

2011-12-01

Full Text Available Seven-year measurements of precipitation, lightning flashes, and visibility from 2000 to 2006 have been analyzed in the Pearl River Delta (PRD region, China, with a focus on the Guangzhou megacity area. Statistical analysis shows that the occurrence of heavy rainfall (>25 mm per day and frequency of lightning strikes are reversely correlated to visibility during this period. To elucidate the effects of aerosols on cloud processes, precipitation, and lightning activity, a cloud resolving – Weather Research and Forecasting (CR-WRF model with a two-moment bulk microphysical scheme is employed to simulate a mesoscale convective system occurring on 28 Match 2009 in the Guangzhou megacity area. The model predicted evolutions of composite radar reflectivity and accumulated precipitation are in agreement with measurements from S-band weather radars and automatic gauge stations. The calculated lightning potential index (LPI exhibits temporal and spatial consistence with lightning flashes recorded by a local lightning detection network. Sensitivity experiments have been performed to reflect aerosol conditions representative of polluted and clean cases. The simulations suggest that precipitation and LPI are enhanced by about 16% and 50%, respectively, under the polluted aerosol condition. Our results suggest that elevated aerosol loading suppresses light and moderate precipitation (less than 25 mm per day, but enhances heavy precipitation. The responses of hydrometeors and latent heat release to different aerosol loadings reveal the physical mechanism for the precipitation and lightning enhancement in the Guangzhou megacity area, showing more efficient mixed phase processes and intensified convection under the polluted aerosol condition.

Controls of {delta}{sup 34}S and {delta}{sup 18}O in dissolved sulphate: Learning from a detailed survey in the Llobregat River (Spain)

Energy Technology Data Exchange (ETDEWEB)

Otero, Neus [Departament Cristal . lografia, Mineralogia i Diposits Minerals, Facultat de Geologia, Universitat de Barcelona, Marti i Franques, s/n, 08028 Barcelona (Spain); Grup d' Hidrogeoquimica, Departament de Geologia Ambiental, Institut de Ciencies de la Terra ' Jaume Almera' , CSIC, Lluis Sole i Sabaris, s/n, 08028 Barcelona (Spain)], E-mail: notero@ub.edu; Soler, Albert; Canals, Angels [Departament Cristal . lografia, Mineralogia i Diposits Minerals, Facultat de Geologia, Universitat de Barcelona, Marti i Franques, s/n, 08028 Barcelona (Spain)

2008-05-15

The S and O isotopic composition of dissolved SO{sub 4}, used as a tracer for SO{sub 4} sources, was applied to the water of the Llobregat River system (NE Spain). The survey was carried out at 30 sites where surface water was sampled on a monthly basis over a period of 2a. The concentration of dissolved SO{sub 4} varied from 20 to 1575 mg L{sup -1}. Sulphur isotopic compositions clustered in two populations: one - 93% of the samples - had positive values with a mode of +9 per mille ; the other had negative values and a mode of -5 per mille . Data for {delta}{sup 18}O{sub SO{sub 4}} showed a mean value of +11 per mille , with no bi-modal distribution, though lower values of {delta}{sup 18}O corresponded to samples with negative {delta}{sup 34}S. These values can not be explained solely by the contribution of bedrock SO{sub 4} sources: that is, sulphide oxidation and the weathering of outcrops of sulphates, though numerous chemical sediments exist in the basin. Even in a river with a high concentration of natural sources of dissolved SO{sub 4}, such as the Llobregat River, the {delta}{sup 34}S values suggest that dissolved SO{sub 4} is controlled by a complex mix of both natural and anthropogenic sources. The main anthropogenic sources in this basin are fertilizers, sewage, potash mine effluent and power plant emissions. Detailed river water sampling, together with the chemical and isotopic characterisation of the main anthropogenic inputs, allowed determination of the influence of redox processes, as well as identification of the contribution of natural and anthropogenic SO{sub 4} sources and detection of spatial variations and seasonal changes among these sources. For instance, in the Llobregat River the input of fertilisers is well marked seasonally. Minimum values of {delta}{sup 34}S are reported during fertilization periods - from January to March - indicating a higher contribution of this source. The dual isotope approach, {delta}{sup 34}S and {delta}{sup 18}O

Spatial and temporal variation of nutrients in groundwater and associated processes in the coastal zone of the Pearl River Delta, China

Science.gov (United States)

Chen, J.

2017-12-01

Rapid urbanization has occurred in the Pearl River Delta since 1980s, resulting in tremendous accumulation of population and material in an area of around 1.1x104 km2. Massive nutrients were released to the coastal zone either via the Pearl River or the aquifer, and effects of these nutrients on ecosystem and drinking water supply are a big public concern. Field campaigns to collect groundwater samples were implemented in rainy (April- September) and dry seasons (October - March) during the period of 2005-2016, and samples were analyzed for major ions, nutrients, multiple isotopes, N2O and microbiological DNA. Seasonal and spatial pattern of nutrients from the recharge to the discharge zone in two case study areas were identified and compared regarding relevant N transformation processes. Main sources of nutrients in groundwater and major mechanisms, e.g. denitrification, nitrification and etc., involved in these processes were raised by integrating microbiological, isotopic and geochemical evidences. Driven forces of the change in nutrients in the past 10 years were investigated based on statistical data, and total nutrient load in groundwater in the delta was estimated.

Evaluating Nitrogen Oxides and Ultrafine Particulate Matter Emission Features of Urban Bus Based on Real-World Driving Conditions in the Yangtze River Delta Area, China

Directory of Open Access Journals (Sweden)

Dengguo Liu

2018-06-01

Full Text Available A Portable Emission Measurement System was used in this study to evaluate the exhaust emission characteristics of nitrogen oxides (NOx, ultrafine particulate matter (PM, and ultrafine particulate number (PN from buses in the Yangtze River Delta, China. Results showed that NOx emission factor (unit: g·km−1 increased from 5.0 to 19.1, and PM emission factor (unit: g·km−1 increased from 0.001 to 0.189. A nonlinear model was established based on scientific statistical method, which showed that NOx and PM emission factors significantly decreased with speed increasing. The model also showed a “long tail effect” of NOx and PM emission factors beyond 30 km·h−1. Furthermore, hybrid bus exhausted less NOx, PM, and PN emissions compared to conventional bus in the acceleration condition. Exhaust rates of NOx, PM and PN emissions (unit: g·s−1 increased with speed increasing under steady state driving condition, while PN emissions commonly showed a unimodal distribution at the speed of 20 km·h−1.

Assessment of Heavy Metal Pollution and Health Risks in the Soil-Plant-Human System in the Yangtze River Delta, China

Science.gov (United States)

Hu, Bifeng; Jia, Xiaolin; Hu, Jie; Xu, Dongyun; Xia, Fang; Li, Yan

2017-01-01

Heavy metal (HM) contamination and accumulation is a serious problem around the world due to the toxicity, abundant sources, non-biodegradable properties, and accumulative behaviour of HMs. The degree of soil HM contamination in China, especially in the Yangtze River Delta, is prominent. In this study, 1822 pairs of soil and crop samples at corresponding locations were collected from the southern Yangtze River Delta of China, and the contents of Ni, Cr, Zn, Cd, As, Cu, Hg, and Pb were measured. The single pollution index in soil (SPI) and Nemerow composite pollution index (NCPI) were used to assess the degree of HM pollution in soil, and the crop pollution index (CPI) was used to explore the degree of HM accumulation in crops. The bioaccumulation factor (BAF) was used to investigate the translocation of heavy metals in the soil-crop system. The health risks caused by HMs were calculated based on the model released by the U.S. Environmental Protection Agency. The SPIs of all elements were at the unpolluted level. The mean NCPI was at the alert level. The mean CPIs were in the following decreasing order: Ni (1.007) > Cr (0.483) > Zn (0.335) > Cd (0.314) > As (0.232) > Cu (0.187) > Hg (0.118) > Pb (0.105). Only the mean content of Ni in the crops exceeded the national standard value. The standard exceeding rates were used to represent the percentage of samples whose heavy metal content is higher than the corresponding national standard values. The standard exceeding rates of Cu, Hg, and Cd in soil were significantly higher than corresponding values in crops. Meanwhile, the standard exceeding rates of Ni, As, and Cr in crops were significantly higher than corresponding values in soil. The chronic daily intake (CDI) of children (13.8 × 10−3) was the largest among three age groups, followed by adults (6.998 × 10−4) and seniors (5.488 × 10−4). The bioaccumulation factors (BAFs) of all crops followed the order Cd (0.249) > Zn (0.133) > As (0.076) > Cu (0.064) > Ni

Assessment of Heavy Metal Pollution and Health Risks in the Soil-Plant-Human System in the Yangtze River Delta, China.

Science.gov (United States)

Hu, Bifeng; Jia, Xiaolin; Hu, Jie; Xu, Dongyun; Xia, Fang; Li, Yan

2017-09-10

Heavy metal (HM) contamination and accumulation is a serious problem around the world due to the toxicity, abundant sources, non-biodegradable properties, and accumulative behaviour of HMs. The degree of soil HM contamination in China, especially in the Yangtze River Delta, is prominent. In this study, 1822 pairs of soil and crop samples at corresponding locations were collected from the southern Yangtze River Delta of China, and the contents of Ni, Cr, Zn, Cd, As, Cu, Hg, and Pb were measured. The single pollution index in soil (SPI) and Nemerow composite pollution index (NCPI) were used to assess the degree of HM pollution in soil, and the crop pollution index (CPI) was used to explore the degree of HM accumulation in crops. The bioaccumulation factor (BAF) was used to investigate the translocation of heavy metals in the soil-crop system. The health risks caused by HMs were calculated based on the model released by the U.S. Environmental Protection Agency. The SPIs of all elements were at the unpolluted level. The mean NCPI was at the alert level. The mean CPIs were in the following decreasing order: Ni (1.007) > Cr (0.483) > Zn (0.335) > Cd (0.314) > As (0.232) > Cu (0.187) > Hg (0.118) > Pb (0.105). Only the mean content of Ni in the crops exceeded the national standard value. The standard exceeding rates were used to represent the percentage of samples whose heavy metal content is higher than the corresponding national standard values. The standard exceeding rates of Cu, Hg, and Cd in soil were significantly higher than corresponding values in crops. Meanwhile, the standard exceeding rates of Ni, As, and Cr in crops were significantly higher than corresponding values in soil. The chronic daily intake (CDI) of children (13.8 × 10 -3 ) was the largest among three age groups, followed by adults (6.998 × 10 -4 ) and seniors (5.488 × 10 -4 ). The bioaccumulation factors (BAFs) of all crops followed the order Cd (0.249) > Zn (0.133) > As (0.076) > Cu (0.064) > Ni

Nitrogen Leaching in Intensive Cropping Systems in Tam Duong District, Red River Delta of Vietnam

OpenAIRE

Trinh, M.V.; Keulen, van, H.; Roetter, R.P.

2010-01-01

The environmental and economic consequences of nitrogen (N) lost in rice-based systems in Vietnam is important but has not been extensively studied. The objective of this study was to quantify the amount of N lost in major cropping systems in the Red River Delta. An experiment was conducted in the Red River Delta of Vietnam, on five different crops including rose, daisy, cabbage, chili, and a rice–rice–maize rotation during 2004 and 2005. Core soil samples were taken periodically in 20-cm inc...

Soil Organic Carbon Stocks in Arctic Deltaic Sediments: Investigations in the Lena River Delta.

Science.gov (United States)

Zubrzycki, S.; Kutzbach, L.; Desyatkin, A.; Pfeiffer, E.-M.

2012-04-01

The soil organic carbon stock (SSOC) of deltaic sediments in arctic permafrost regions is known to be significant but is insufficiently investigated so far. Previous SSOC studies were conducted mainly in the comparatively well studied Mackenzie River Delta (area: 13,000 km2) in Canada. The few studies from other arctic delta regions report only the gravimetric carbon (C) contents and are limited to the active layer depth at the time of sampling. Since C deposits in permafrost regions are likely to become a future C source, more detailed investigations of the presently frozen likely carbon-rich sediment and soil layers in other arctic delta regions are of importance. Our investigations were performed on Samoylov Island in the southern-central part of the Lena River Delta (32,000 km2) which is the largest arctic delta and the fifth largest delta worldwide. Samoylov Island is representative for the Lena River Delta's first terrace and the active floodplains. Within this study a new portable Snow-Ice-Permafrost-Research-Establishment (SIPRE) auger was used during a spring field session to obtain 1 m deep frozen soil cores (n = 37) distributed over all known soil and vegetation units. These cores are analyzed for bulk contents of nitrogen (N) and C, ice content and bulk density (BD) and to determine the SSOC including the rarely investigated currently permanently frozen layers up to 1 m depth on Samoylov Island. Our study provides evidence for high SSOC for a depth of 1 m for the investigated area ranging between 6 kg m2 and 54 kg m2. Considering the spatial extent of different soil units on the two geomorphological units of Samoylov Island, the area-weighted average SSOC were 31 kg m2 (n = 31) for the first terrace and 15 kg m2 (n = 6) for the active floodplain. For the correspondent soil units of Turbels and Orthels in circumpolar permafrost regions, Tarnocai et al. 2009 reported a mean SSOC of 27 kg m2 (min: 0.1 kg m2, max: 126 kg m2) for a depth of 1 m. For up

Science-policy interplay: Air quality management in the Pearl River Delta region and Hong Kong

Science.gov (United States)

Zhong, Liuju; Louie, Peter K. K.; Zheng, Junyu; Yuan, Zibing; Yue, Dingli; Ho, Josephine W. K.; Lau, Alexis K. H.

2013-09-01

The information provided by the scientific studies and control measures implemented in the Pearl River Delta (PRD) region of China reveals that tremendous progress has been made in the understanding of regional air pollution issues and the deployment of mitigation measures for alleviating these problems. Given the unparalleled rapid economic growth in the PRD over the past two decades, such progress was only made possible by strong, science-based support and the partnerships between government and research institutions in the region and overseas. Researchers from these partnership programs and related studies have deployed cutting-edge expertise and experience in various crucial mainland China and mainland China/Hong Kong-level projects. China recognizes the importance of protecting the environment and cleaning up the air in the pursuit of sustainable growth and economic development. To avoid falling into a cycle of event-driven clean-up efforts, China has recently taken a major step and updated the national ambient air quality standards. Clearly, China is implementing an increasing number of evidence-based policies to address air pollution problems. Thus, to bring a fresh impetus at a national level, the PRD must maintain and augment the Hong Kong-mainland collaborative momentum, inducing a "whole-China" effort to clean up air pollution. To strengthen the science-based support system and ensure continuous and concerted effort in implementing the regional multi-pollutant control strategy, there must be an overarching and integral Hong Kong-Guangdong science consortium framework supporting the formulation of regional policy and control measures built on common goals under the "one country, two systems" principle. The "PRD Approach" of the air quality management regime reflected regional cooperative efforts in synchronous air pollutant control, catalyzed the crucial role of information disclosure and subtly transformed the air quality management approach to overcome

Community-based restoration of desert wetlands: the case of the Colorado River delta

Science.gov (United States)

Osvel Hinojosa-Huerta; Mark Briggs; Yamilett Carrillo-Guerroro; Edward P. Glenn; Miriam Lara-Flores; Martha Roman-Rodriguez

2005-01-01

Wetland areas have been drastically reduced through the Pacific Flyway and the Sonoran Desert, with severe consequences for avian populations. In the Colorado River delta, wetlands have been reduced by 80 percent due to water management practices in the Colorado River basin. However, excess flows and agricultural drainage water has restored some areas, providing...

Hourly peak concentration measuring the PM2.5-mortality association: Results from six cities in the Pearl River Delta study

Science.gov (United States)

Lin, Hualiang; Ratnapradipa, Kendra; Wang, Xiaojie; Zhang, Yonghui; Xu, Yanjun; Yao, Zhenjiang; Dong, Guanghui; Liu, Tao; Clark, Jessica; Dick, Rebecca; Xiao, Jianpeng; Zeng, Weilin; Li, Xing; Qian, Zhengmin (Min); Ma, Wenjun

2017-07-01

Compared with daily mean concentration of air pollution, hourly peak concentration may be more directly relevant to the acute health effects due to the high concentration levels, however, few have analyzed the acute mortality effects of hourly peak levels of air pollution. We examined the associations of hourly peak concentration of fine particulate matter air pollution (PM2.5) with mortality in six cities in Pearl River Delta, China. We used generalized additive Poisson models to examine the associations with adjustment for potential confounders in each city. We further applied random-effects meta-analyses to estimate the regional overall effects. We further estimated the mortality burden attributable to hourly peak and daily mean PM2.5. We observed significant associations between hourly peak PM2.5 and mortality. Each 10 μg/m3 increase in 4-day averaged (lag03) hourly peak PM2.5 corresponded to a 0.9% [95% confidence interval (CI): 0.7%, 1.1%] increase in total mortality, 1.2% (95% CI: 1.0%, 1.5%) in cardiovascular mortality, and 0.7% (95% CI: 0.2%, 1.1%) in respiratory mortality. We observed a greater mortality burden using hourly peak PM2.5 than daily mean PM2.5, with an estimated 12915 (95% CI: 9922, 15949) premature deaths attributable to hourly peak PM2.5, and 7951 (95% CI: 5067, 10890) to daily mean PM2.5 in the Pearl River Delta (PRD) region during the study period. This study suggests that hourly peak PM2.5 might be one important risk factor of mortality in PRD region of China; the finding provides important information for future air pollution management and epidemiological studies.

Process analysis and sensitivity study of regional ozone formation over the Pearl River Delta, China, during the PRIDE-PRD2004 campaign using the Community Multiscale Air Quality modeling system

Directory of Open Access Journals (Sweden)

X. Wang

2010-05-01

Full Text Available In this study, the Community Multiscale Air Quality (CMAQ modeling system is used to simulate the ozone (O₃ episodes during the Program of Regional Integrated Experiments of Air Quality over the Pearl River Delta, China, in October 2004 (PRIDE-PRD2004. The simulation suggests that O₃ pollution is a regional phenomenon in the Pearl River Delta (PRD. Elevated O₃ levels often occurred in the southwestern inland PRD, Pearl River estuary (PRE, and southern coastal areas during the 1-month field campaign. Three evolution patterns of simulated surface O₃ are summarized based on different near-ground flow conditions. More than 75% of days featured interactions between weak synoptic forcing and local sea-land circulation. Integrated process rate (IPR analysis shows that photochemical production is a dominant contributor to O₃ enhancement from 09:00 to 15:00 local standard time in the atmospheric boundary layer over most areas with elevated O₃ occurrence in the mid-afternoon. The simulated ozone production efficiency is 2–8 O₃ molecules per NO_x molecule oxidized in areas with high O₃ chemical production. Precursors of O₃ originating from different source regions in the central PRD are mixed during the course of transport to downwind rural areas during nighttime and early morning, where they then contribute to the daytime O₃ photochemical production. The sea-land circulation plays an important role on the regional O₃ formation and distribution over PRD. Sensitivity studies suggest that O₃ formation is volatile-organic-compound-limited in the central inland PRD, PRE, and surrounding coastal areas with less chemical aging (NO_x/NO_y>0.6, but is NO_x-limited in the rural southwestern PRD with aged air (NO_x/NO_y<0.3.

Formation Conditions and Sedimentary Characteristics of a Triassic Shallow Water Braided Delta in the Yanchang Formation, Southwest Ordos Basin, China.

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Ziliang Liu

Full Text Available A large, shallow braided river delta sedimentary system developed in the Yanchang Formation during the Triassic in the southwest of the Ordos basin. In this braided delta system, abundant oil and gas resources have been observed, and the area is a hotspot for oil and gas resource exploration. Through extensive field work on outcrops and cores and analyses of geophysical data, it was determined that developments in the Late Triassic produced favorable geological conditions for the development of shallow water braided river deltas. Such conditions included a large basin, flat terrain, and wide and shallow water areas; wet and dry cyclical climate changes; ancient water turbulence; dramatic depth cycle changes; ancient uplift development; strong weathering of parent rock; and abundant supply. The shallow water braided river delta showed grain sediment granularity, plastic debris, and sediment with mature composition and structure that reflected the strong hydrodynamic environment of large tabular cross-bedding, wedge cross-bedding, and multiple positive rhythms superimposed to form a thick sand body layer. The branch river bifurcation developed underwater, and the thickness of the sand body increased further, indicating that the slope was slow and located in shallow water. The seismic responses of the braided river delta reflected strong shallow water performance, indicated by a progradation seismic reflection phase axis that was relatively flat; in addition, the seismic reflection amplitude was strong and continuous with a low angle and extended over considerable distances (up to 50 km. The sedimentary center was close to the provenance, the width of the river was large, and a shallow sedimentary structure and a sedimentary rhythm were developed. The development of the delta was primarily controlled by tectonic activity and changes in the lake level; as a result, the river delta sedimentary system eventually presented a "small plain, big front

Formation Conditions and Sedimentary Characteristics of a Triassic Shallow Water Braided Delta in the Yanchang Formation, Southwest Ordos Basin, China.

Science.gov (United States)

Liu, Ziliang; Shen, Fang; Zhu, Xiaomin; Li, Fengjie; Tan, Mengqi

2015-01-01

A large, shallow braided river delta sedimentary system developed in the Yanchang Formation during the Triassic in the southwest of the Ordos basin. In this braided delta system, abundant oil and gas resources have been observed, and the area is a hotspot for oil and gas resource exploration. Through extensive field work on outcrops and cores and analyses of geophysical data, it was determined that developments in the Late Triassic produced favorable geological conditions for the development of shallow water braided river deltas. Such conditions included a large basin, flat terrain, and wide and shallow water areas; wet and dry cyclical climate changes; ancient water turbulence; dramatic depth cycle changes; ancient uplift development; strong weathering of parent rock; and abundant supply. The shallow water braided river delta showed grain sediment granularity, plastic debris, and sediment with mature composition and structure that reflected the strong hydrodynamic environment of large tabular cross-bedding, wedge cross-bedding, and multiple positive rhythms superimposed to form a thick sand body layer. The branch river bifurcation developed underwater, and the thickness of the sand body increased further, indicating that the slope was slow and located in shallow water. The seismic responses of the braided river delta reflected strong shallow water performance, indicated by a progradation seismic reflection phase axis that was relatively flat; in addition, the seismic reflection amplitude was strong and continuous with a low angle and extended over considerable distances (up to 50 km). The sedimentary center was close to the provenance, the width of the river was large, and a shallow sedimentary structure and a sedimentary rhythm were developed. The development of the delta was primarily controlled by tectonic activity and changes in the lake level; as a result, the river delta sedimentary system eventually presented a "small plain, big front" character.

Source apportionment of atmospheric mercury pollution in China using the GEOS-Chem model.

Science.gov (United States)

Wang, Long; Wang, Shuxiao; Zhang, Lei; Wang, Yuxuan; Zhang, Yanxu; Nielsen, Chris; McElroy, Michael B; Hao, Jiming

2014-07-01

China is the largest atmospheric mercury (Hg) emitter in the world. Its Hg emissions and environmental impacts need to be evaluated. In this study, China's Hg emission inventory is updated to 2007 and applied in the GEOS-Chem model to simulate the Hg concentrations and depositions in China. Results indicate that simulations agree well with observed background Hg concentrations. The anthropogenic sources contributed 35-50% of THg concentration and 50-70% of total deposition in polluted regions. Sensitivity analysis was performed to assess the impacts of mercury emissions from power plants, non-ferrous metal smelters and cement plants. It is found that power plants are the most important emission sources in the North China, the Yangtze River Delta (YRD) and the Pearl River Delta (PRD) while the contribution of non-ferrous metal smelters is most significant in the Southwest China. The impacts of cement plants are significant in the YRD, PRD and Central China. Copyright © 2014 Elsevier Ltd. All rights reserved.

Estimation of health and economic costs of air pollution over the Pearl River Delta region in China.

Science.gov (United States)

Lu, Xingcheng; Yao, Teng; Fung, Jimmy C H; Lin, Changqing

2016-10-01

The Pearl River Delta region (PRD) is the economic growth engine of China and also one of the most urbanized regions in the world. As a two-sided sword, rapid economic development causes air pollution and poses adverse health effects to the citizens in this area. This work estimated the negative health effects in the PRD caused by the four major ambient pollutants (SO2, NO2, O3 and PM10) from 2010 to 2013 by using a log linear exposure-response function and the WRF-CMAQ modeling system. Economic loss due to mortality and morbidity was evaluated by the value of statistical life (VSL) and cost of illness (COI) methods. The results show that the overall possible short-term all-cause mortality due to NO2, O3 and PM10 reached the highest in 2013 with the values being 13,217-22,800. The highest total economic loss, which ranged from 14,768 to 25,305million USD, occurred in 2013 and was equivalent to 1.4%-2.3% of the local gross domestic product. The monthly profile of cases of negative health effects varied by city and the types of ambient pollutants. The ratio of mortality attributed to air pollutants to total population was higher in urban areas than in rural areas. People living in the countryside should consider the possible adverse health effects of urban areas before they plan a move to the city. The results show that the health burden caused by the ambient pollutants over this region is serious and suggest that tighter control policies should be implemented in the future to reduce the level of air pollution. Copyright © 2016 Elsevier B.V. All rights reserved.

Télédétection par satellite et SIG pour l'analyse des déplacements des chenaux dans le delta actif de la Rivière Jaune en ChineTeledetección satelitária y SIG para analizar cambios en el desplazamiento de causes en el delta activo del Río Amarillo, China

Science.gov (United States)

Yang, Xiaojun; Damen, Michiel C. J.; van Zuidam, Robert A.

Channel migration in deltaic lowlands tends to be complicated by marine processes and intensified cultural practices. Understanding the ways in which river channels have migrated through time is critical to tackling many geomorphologic and river management problems. Because of large magnitude and rapid rates of change, special surveillance systems are needed to efficiently measure and monitor channel migration. This study presents an application of geographic information technologies for the study of channel migration in the active Yellow River Delta, China. The main source of data was a series of time-sequential Landsat images spanning a period of approximately 19 years. A geographic information system (GIS) was used to support modernized channel position mapping and measurement. The spatio-temporal changes of river banks and channel centerlines were systematically examined, and an attempt was made to relate these computational results with appropriate natural and human processes affecting the delta. This study demonstrates the utility of satellite remote sensing integrated with a GIS in investigating channel migration.

Cryostratigraphy, sedimentology, and the late Quaternary evolution of the Zackenberg River delta, northeast Greenland

DEFF Research Database (Denmark)

Gilbert, Graham L.; Cable, Stefanie; Thiel, Christine

2017-01-01

The Zackenberg River delta is located in northeast Greenland (74 degrees 30' N, 20 degrees 30' E) at the outlet of the Zackenberg fjord valley. The fjord-valley fill consists of a series of terraced deltaic deposits (ca. 2 km2) formed during relative sea-level (RSL) fall. We investigated the depo......The Zackenberg River delta is located in northeast Greenland (74 degrees 30' N, 20 degrees 30' E) at the outlet of the Zackenberg fjord valley. The fjord-valley fill consists of a series of terraced deltaic deposits (ca. 2 km2) formed during relative sea-level (RSL) fall. We investigated...... the deposits using sedimentological and cryostratigraphic techniques together with optically stimulated luminescence (OSL) dating. We identify four facies associations in sections (4 to 22 m in height) exposed along the modern Zackenberg River and coast. Facies associations relate to (I) overriding glaciers......, (II) retreating glaciers and quiescent glaciomarine conditions, (III) delta progradation in a fjord valley, and (IV) fluvial activity and niveo-aeolian processes. Pore, layered, and suspended cryofacies are identified in two 20 m deep ice-bonded sediment cores. The cryofacies distribution, together...

Determining the contributions of urbanisation and climate change to NPP variations over the last decade in the Yangtze River Delta, China.

Science.gov (United States)

Wu, Shaohua; Zhou, Shenglu; Chen, Dongxiang; Wei, Zongqiang; Dai, Liang; Li, Xingong

2014-02-15

Terrestrial net primary production (NPP) is an important measure of global change, and identifying the relative contributions of urbanisation and climate change to NPP is important for understanding the impact of human and natural influences on terrestrial systems and the carbon cycle. The objective of this study was to reveal how urbanisation and climate drive changes in NPP. Satellite-based estimates of NPP collected over a 12-year period (1999-2010) were analysed to identify NPP variations in the Yangtze River Delta. Temporal and spatial analysis methods were used to identify the relationships among NPP, nighttime light urbanisation index values, and climatic factors from pixel to regional scales. The NPP of the entire Yangtze River Delta decreased slightly at a rate of -0.5 g C m(-2)a(-1) from 1999 to 2010, but this change was not significant. However, in the urban region, NPP decreased significantly (pclimate change to NPP variation. The results revealed that the urbanisation factor is the main driving force for NPP change in high-speed urbanisation areas, and the factor accounted for 47% of the variations. However, in the forest and farm regions, the NPP variation was mainly controlled by climate change and residual factors. Copyright © 2013 Elsevier B.V. All rights reserved.

Chemical composition, sources and evolution processes of aerosol at an urban site in Yangtze River Delta, China during wintertime

Science.gov (United States)

Zhang, Yunjiang; Tang, Lili; Yu, Hongxia; Wang, Zhuang; Sun, Yele; Qin, Wei; Chen, Wentai; Chen, Changhong; Ding, Aijun; Wu, Jing; Ge, Shun; Chen, Cheng; Zhou, Hong-cang

2015-12-01

To investigate the composition, sources and evolution processes of submicron aerosol during wintertime, a field experiment was conducted during December 1-31, 2013 in urban Nanjing, a megacity in Yangtze River Delta of China. Non-refractory submicron aerosol (NR-PM1) species were measured with an Aerodyne Aerosol Chemical Speciation Monitor. NR-PM1 is dominated by secondary inorganic aerosol (55%) and organic aerosol (OA, 42%) during haze periods. Six OA components were identified by positive matrix factorization of the OA mass spectra. The hydrocarbon-like OA and cooking-related OA represent the local traffic and cooking sources, respectively. A highly oxidized factor related to biomass burning OA accounted for 15% of the total OA mass during haze periods. Three types of oxygenated OA (OOA), i.e., a less-oxidized OOA (LO-OOA), a more-oxidized OOA (MO-OOA), and a low-volatility OOA (LV-OOA), were identified. LO-OOA is likely associated with fresh urban secondary OA. MO-OOA likely represents photochemical products showing a similar diurnal cycle to nitrate with a pronounced noon peak. LV-OOA appears to be a more oxidized factor with a pronounced noon peak. The OA composition is dominated by secondary species, especially during haze events. LO-OOA, MO-OOA and LV-OOA on average account for 11%, (18%), 24% (21%) and 23% (18%) of the total OA mass for the haze (clean) periods respectively. Analysis of meteorological influence suggested that regional transport from the northern and southeastern areas of the city is responsible for large secondary and low-volatility aerosol formation.

Biogeochemical features of aquatic plants in the Selenga River delta

Science.gov (United States)

Shinkareva, Galina; Lychagin, Mikhail

2014-05-01

The Selenga River system provides more than a half of the Lake Baikal total inflow. The river collects a significant amount of pollutants (e.g. heavy metals) from the whole basin. These substances are partially deposited within the Selenga delta, and partially are transported further to the lake. A generous amount of aquatic plants grow in the delta area according to its favorable conditions. This vegetation works as a specific biofilter. It accumulates suspended particles and sorbs some heavy metals from the water. The study aimed to reveal the species of macrophytes which could be mostly important for biomonitoring according to their chemical composition. The field campaign took place in the Selenga River delta in July-August of 2011 (high water period) and in June of 2012 (low water period). 14 species of aquatic plants were collected: water starwort Callitriche hermaphroditica, small yellow pond lily Nuphar pumila, pondweeds Potamogeton crispus, P. pectinatus, P. friesii, broadleaf cattail Typha latifolia, hornwort or coontail Ceratophyllum demersum, arrowhead Sagittaria natans, flowering rush (or grass rush) Butomus umbellatus, reed Phragmites australis, parrot's feather Myriophyllum spicatum, the common mare's tail Hippuris vulgaris, Batrachium trichophyllum, canadian waterweed Elodea canadensis. The samples were dried, grinded up and digested in a mixture of HNO3 and H2O2. The chemical composition of the plant material was defined using ICP-MS and ICP-AES methods. Concentrations of Fe, Mn, Cr, Ni, Cu, B, Zn, V, Co, As, Mo, Pb, and U were considered. The study revealed that Potamogeton pectinatus and Myriophyllum spicatum concentrate elements during both high and low water periods. Conversely the Butomus umbellatus and Phragmites australis contain small amount of heavy metals. The reed as true grasses usually accumulates fewer amounts of elements than other macrophytes. To compare biogeochemical specialization of different species we suggest to use

River-plume sedimentation and 210Pb/7Be seabed delivery on the Mississippi River delta front

Science.gov (United States)

Keller, Gregory; Bentley, Samuel J.; Georgiou, Ioannis Y.; Maloney, Jillian; Miner, Michael D.; Xu, Kehui

2017-06-01

To constrain the timing and processes of sediment delivery and submarine mass-wasting events spanning the last few decades on the Mississippi River delta front, multi-cores and gravity cores (0.5 and water depth in 2014. The cores were analyzed for radionuclide activity (7Be, 210Pb, 137Cs), grain size, bulk density, and fabric (X-radiography). Core sediments are faintly bedded, sparsely bioturbated, and composed mostly of clay and fine silt. Short-term sedimentation rates (from 7Be) are 0.25-1.5 mm/day during river flooding, while longer-term accumulation rates (from 210Pb) are 1.3-7.9 cm/year. In most cores, 210Pb activity displays undulatory profiles with overall declining activity versus depth. Undulations are not associated with grain size variations, and are interpreted to represent variations in oceanic 210Pb scavenging by river-plume sediments. The 210Pb profile of one gravity core from a mudflow gully displays uniform basal excess activity over a zone of low and uniform bulk density, interpreted to be a mass-failure event that occurred 9-18 years before core collection. Spatial trends in sediment deposition (from 7Be) and accumulation (from 210Pb) indicate that proximity to the river mouth has stronger influence than local facies (mudflow gully, depositional lobe, prodelta) over the timeframe and seabed depth represented by the cores (sediment deposition from river plumes coupled with infrequent tropical cyclone activity near the delta in the last 7 years (2006-2013), and by the location of most sediment failure surfaces (from mass flows indicated by parallel geophysical studies) deeper than the core-sampling depths of the present study.

Driving forces and their contribution to the recent decrease in sediment flux to ocean of major rivers in China.

Science.gov (United States)

Li, Tong; Wang, Shuai; Liu, Yanxu; Fu, Bojie; Zhao, Wenwu

2018-09-01

Understanding the mechanisms behind land-ocean sediment transport processes is crucial, due to the resulting impacts on the sustainable management of water and soil resources. This study investigated temporal trends and historical phases of sediment flux delivered to the sea by nine major rivers in China, while also quantifying the contribution of key anthropogenic and natural driving forces. During the past six decades, sediment flux from these nine major rivers exhibited a statistically significant negative trend, decreasing from 1.92Gtyr -1 during 1954-1968 to 1.39Gtyr -1 , 0.861Gtyr -1 and 0.335Gtyr -1 during 1969-1985, 1986-1999 and 2000-2016, respectively. We used a recently developed Sediment Identity approach and found that the sharp decrease in sediment load observed across China was mainly (~95%) caused by a reduction in sediment concentration. Reservoir construction exerted the strongest influence on land-ocean sediment fluxes, while soil conservation measures represented a secondary driver. Before 1999, soil erosion was not controlled effectively in China and reservoirs, especially large ones, played a dominant role in reducing riverine sediments. After 1999, soil erosion has gradually been brought under control across China, so that conservation measures directly accounted for ~40% of the observed decrease in riverine sediments. With intensifying human activities, it is predicted that the total sediment flux delivered to the sea by the nine major rivers will continue to decrease in the coming decades, although at a slower rate, resulting in severe challenges for the sustainable management of drainage basins and river deltas. Copyright © 2018 Elsevier B.V. All rights reserved.

Late Quaternary Stratigraphic Architecture of the Santee River Delta, South Carolina, U.S.A.

Science.gov (United States)

Long, J. H.; Hanebuth, T. J. J.

2017-12-01

The Santee River of South Carolina is the second largest river in terms of drainage area and discharge in the eastern United States and forms the only river-fed delta on the country's Atlantic coast. Significant anthropogenic modifications to this system date back to the early 18th century with the extensive clearing of coastal wetland forest for rice cultivation. In the 1940's the construction of large upstream dams permanently altered the discharge of the Santee River. These modifications are likely documented within the sedimentary record of the Santee Delta as episodes of major environmental changes. The Piedmont-sourced Santee River system incised its valley to an estimated depth of 20 m during lower glacial sea level. Sedimentation during the subsequent Holocene transgression and highstand has filled much of this accommodation. The Santee system remains largely under-investigated with only a handful of studies completed in the 1970's and 1980's based on sediment cores and cuttings. Through the use of high frequency seismic profiles (0.5 - 24 kHz), sediment cores, and other field data, we differentiate depositional units, architectural elements, and bounding surfaces with temporal and spatial distributions reflecting the changing morphodynamics of this complex system at multiple scales. These lithosomes are preserved within both modern inshore and offshore settings and were deposited within a range of paralic environments by processes active on fluvial/estuarine bars, floodplains, marshes, tidal flats, spits, beach ridges, and in backbarrier settings. They are bound by surfaces ranging from diastems to regional, polygenetic, low-angle and channel-form erosional surfaces. Detailed descriptions of cores taken from within the upper 6 m of the modern lower delta plain document heterolithic, mixed-energy, organic-rich, largely aggradational sedimentation dating back to at least 5 ka cal BP. Offshore, stacked, sand-rich, progradational packages sit atop heterolithic

Dispersion Mechanisms of a Tidal River Junction in the Sacramento–San Joaquin Delta, California

Directory of Open Access Journals (Sweden)

Karla T. Gleichauf

2014-12-01

Full Text Available doi: http://dx.doi.org/10.15447/sfews.2014v12iss4art1In branching channel networks, such as in the Sacramento–San Joaquin River Delta, junction flow dynamics contribute to dispersion of ecologically important entities such as fish, pollutants, nutrients, salt, sediment, and phytoplankton. Flow transport through a junction largely arises from velocity phasing in the form of divergent flow between junction channels for a portion of the tidal cycle. Field observations in the Georgiana Slough junction, which is composed of the North and South Mokelumne rivers, Georgiana Slough, and the Mokelumne River, show that flow phasing differences between these rivers arise from operational, riverine, and tidal forcing. A combination of Acoustic Doppler Current Profile (ADCP boat transecting and moored ADCPs over a spring–neap tidal cycle (May to  June 2012 monitored the variability of spatial and temporal velocity, respectively. Two complementary drifter studies enabled assessment of local transport through the junction to identify small-scale intrajunction dynamics. We supplemented field results with numerical simulations using the SUNTANS model to demonstrate the importance of phasing offsets for junction transport and dispersion. Different phasing of inflows to the junction resulted in scalar patchiness that is characteristic of MacVean and Stacey’s (2011 advective tidal trapping. Furthermore, we observed small-scale junction flow features including a recirculation zone and shear layer, which play an important role in intra-junction mixing over time scales shorter than the tidal cycle (i.e., super-tidal time scales. The study period spanned open- and closed-gate operations at the Delta Cross Channel. Synthesis of field observations and modeling efforts suggest that management operations related to the Delta Cross Channel can strongly affect transport in the Delta by modifying the relative contributions of tidal and riverine flows, thereby

Coastal processes of the Elwha River delta: Chapter 5 in Coastal habitats of the Elwha River, Washington--biological and physical patterns and processes prior to dam removal

Science.gov (United States)

Warrick, Jonathan A.; Stevens, Andrew W.; Miller, Ian M.; Gelfenbaum, Guy; Duda, Jeffrey J.; Warrick, Jonathan A.; Magirl, Christopher S.

2011-01-01

To understand the effects of increased sediment supply from dam removal on marine habitats around the Elwha River delta, a basic understanding of the region’s coastal processes is necessary. This chapter provides a summary of the physical setting of the coast near the Elwha River delta, for the purpose of synthesizing the processes that move and disperse sediment discharged by the river. One fundamental property of this coastal setting is the difference between currents in the surfzone with those in the coastal waters offshore of the surfzone. Surfzone currents are largely dictated by the direction and size of waves, and the waves that attack the Elwha River delta predominantly come from Pacific Ocean swell from the west. This establishes surfzone currents and littoral sediment transport that are eastward along much of the delta. Offshore of the surfzone the currents are largely influenced by tidal circulation and the physical constraint to flow provided by the delta’s headland. During both ebbing and flooding tides, the flow separates from the coast at the tip of the delta’s headland, and this produces eddies on the downstream side of the headland. Immediately offshore of the Elwha River mouth, this creates a situation in which the coastal currents are directed toward the east much more frequently than toward the west. This suggests that Elwha River sediment will be more likely to move toward the east in the coastal system.

The evolution of a subaqueous delta in the Anthropocene: A stratigraphic investigation of the Brazos River delta, TX USA

Science.gov (United States)

Carlin, Joseph A.; Dellapenna, Timothy M.

2015-12-01

Globally, deltas are increasingly threatened by anthropogenic activities. As a result, deltas now evolve through the combined effects of natural and human-induced processes occurring throughout the fluvial-deltaic system. The Brazos River delta, located along the Texas coast in the northwestern Gulf of Mexico, and its watershed have been impacted by direct and indirect human activities since the late 19th century. This provides an opportunity to investigate how such alterations have shaped the evolution of a delta in the Anthropocene, a time when humans are drivers of geological change. Historic alteration to the delta and watershed include extensive agricultural activity, jetty construction at the mouth in the late 1890s, mouth diversion ~10 km to the southwest in 1929, and reservoir construction throughout the early and mid 20th Century. Three subaerial deltaic geometries provided the framework to connect subaerial deltaic responses, to the anthropogenic alterations, to the resulting stratigraphic characteristics observed in the subaqueous delta. This study utilized high-resolution geophysical data (swath bathymetry, side scan sonar, CHIRP subbottom profiling) on the subaqueous delta to investigate the subaqueous delta stratigraphy and infer the processes that shaped the deltaic record over time. The results showed distinct areas across the subaqueous delta that were dominated by erosion and deposition. Erosional areas corresponded to earlier growth phase depocenters being exposed at the surface, while the depositional areas corresponded to areas with the most recent growth phase depocenter overlying the earlier depocenters. These results highlight that the subaqueous depocenter has migrated westward over time, consistent with the observed changes to the subaerial delta. Additionally, the data showed that evidence for these past growth phases and depocenters may be preserved within the subaqueous delta, even after subaerial portions of the delta returned to pre

Challenges, Approaches and Experiences from Asian Deltas and the Rhine-Meuse Delta : Regional Training Workshop on Delta Planning and Management

NARCIS (Netherlands)

Wosten, J.H.M.; Douven, W.; Long Phi, H.; Fida Abdullah Khan, M.

2013-01-01

River delta's, like the Mekong Delta (Vietnam), Ganges-Brahmaputra Delta (Bangladesh), Ayeyarwady Delta (Myanmar), Nile (Egypt) and Ciliwung Delta (Indonesia) are developing rapidly and are characterised by large-scale urbanisation and industrialization processes. They are facing serious planning

Process connectivity in a naturally prograding river delta

Science.gov (United States)

Sendrowski, Alicia; Passalacqua, Paola

2017-03-01

River deltas are lowland systems that can display high hydrological connectivity. This connectivity can be structural (morphological connections), functional (control of fluxes), and process connectivity (information flow from system drivers to sinks). In this work, we quantify hydrological process connectivity in Wax Lake Delta, coastal Louisiana, by analyzing couplings among external drivers (discharge, tides, and wind) and water levels recorded at five islands and one channel over summer 2014. We quantify process connections with information theory, a branch of mathematics concerned with the communication of information. We represent process connections as a network; variables serve as network nodes and couplings as network links describing the strength, direction, and time scale of information flow. Comparing process connections at long (105 days) and short (10 days) time scales, we show that tides exhibit daily synchronization with water level, with decreasing strength from downstream to upstream, and that tides transfer information as tides transition from spring to neap. Discharge synchronizes with water level and the time scale of its information transfer compares well to physical travel times through the system, computed with a hydrodynamic model. Information transfer and physical transport show similar spatial patterns, although information transfer time scales are larger than physical travel times. Wind events associated with water level setup lead to increased process connectivity with highly variable information transfer time scales. We discuss the information theory results in the context of the hydrologic behavior of the delta, the role of vegetation as a connector/disconnector on islands, and the applicability of process networks as tools for delta modeling results.

Circuitous to single thread: post-dam geomorphic transformation of the Colorado River in its delta

Science.gov (United States)

Mueller, E. R.; Schmidt, J. C.

2017-12-01

The Colorado River in its delta has transformed from a maze of secondary and distributary channels to an intermittent or ephemeral stream largely disconnected from formerly active channels and floodplains. Periodic post-dam floods have demonstrated that channel migration and shifting during floods increased the extent and diversity of riparian vegetation, and suggested that restoration of fluvial processes that promote re-activation of these former channels may enhance ecosystem rehabilitation. But restoration efforts in the delta are complicated by the fact that the Colorado River has the largest reservoir size in relation to its mean annual flow of any large river in North America and most of its sediment supply is completely blocked in upstream reservoirs. As a result, small controlled floods intended to inundate formerly active channels and rejuvenate riparian vegetation must consider the new relationship between stream flow and the delta's transformed geomorphology. Post-dam channel change has been dominated by the abandonment of secondary and distributary channels, with 3 to 4 meters of bed incision in the upstream part of the delta that diminishes downstream. Initial bed incision of 2 to 3 meters occurred rapidly following completion of Hoover Dam in 1936, before further upstream water development reduced delta flows to near zero by the mid-1960s. The largest post-dam floods occurred in the 1980s, which resulted in 10s to 100s of meters of lateral migration, channel switching, and the reactivation of secondary channels and floodplains rarely inundated since dam completion. Smaller flow pulses in the 1990s and 2000s further incised the thalweg to its minimum elevation, resulting in a narrow single-thread channel inset within the multi-channel surface active during the 1980s. In 2014, an experimental pulse flow was released to the river channel with a peak discharge approximately 5% of the typical pre-dam flood peak. Topographic change was confined to the main

Analysis of relationships between land surface temperature and land use changes in the Yellow River Delta

Science.gov (United States)

Ning, Jicai; Gao, Zhiqiang; Meng, Ran; Xu, Fuxiang; Gao, Meng

2018-06-01

This study analyzed land use and land cover changes and their impact on land surface temperature using Landsat 5 Thematic Mapper and Landsat 8 Operational Land Imager and Thermal Infrared Sensor imagery of the Yellow River Delta. Six Landsat images comprising two time series were used to calculate the land surface temperature and correlated vegetation indices. The Yellow River Delta area has expanded substantially because of the deposited sediment carried from upstream reaches of the river. Between 1986 and 2015, approximately 35% of the land use area of the Yellow River Delta has been transformed into salterns and aquaculture ponds. Overall, land use conversion has occurred primarily from poorly utilized land into highly utilized land. To analyze the variation of land surface temperature, a mono-window algorithm was applied to retrieve the regional land surface temperature. The results showed bilinear correlation between land surface temperature and the vegetation indices (i.e., Normalized Difference Vegetation Index, Adjusted-Normalized Vegetation Index, Soil-Adjusted Vegetation Index, and Modified Soil-Adjusted Vegetation Index). Generally, values of the vegetation indices greater than the inflection point mean the land surface temperature and the vegetation indices are correlated negatively, and vice versa. Land surface temperature in coastal areas is affected considerably by local seawater temperature and weather conditions.

Temporal changes of land use in Asi river delta (Hatay, Southern Turkey).

Science.gov (United States)

Korkmaz, Hüseyin; Cetin, Bayram; Kuscu, Veysel; Ege, Ismail; Bom, Ahmet; Ozsahin, Emre; Karatas, Atilla

2012-04-01

Increasing non-ecological land use necessitates more efficient using and utilization of land by man. Therefore, in recent years studies on sustainable land use have gained momentum. In this study, temporal change in land use, mainly between years 1940 and 2010, in Asi river delta on Southern Turkey was covered. To this end, in addition to literature, topographical maps and satellite images from year 1940 and after were used. Also, data were collected through field studies and interviews. Collected data were evaluated from geographical viewpoint using Geographical information system (GIS) and Remote sensing (RS) methods. Unplanned settlement in delta has reached levels high enough to threaten agricultural fields. Especially, greattendencyshown by Samandag city and the villages around it towards expanding into delta is an indicatorof this threat In additon, uncontrolled sand mining and touristic facilities on the coastline are also indicators of wrong land use. In future, direction of settlement to slopes around the delta rather than lowlands will be a much more ecological approach.

Influence of habitat heterogeneity on anuran diversity in Restinga landscapes of the Parnaíba River delta, northeastern Brazil.

Science.gov (United States)

Araújo, Kássio C; Guzzi, Anderson; Ávila, Robson W

2018-01-01

Anurans have close associations with environmental conditions and therefore represent an interesting vertebrate group for examining how resource availability and environmental variables influence species diversity. Associations between habitat heterogeneity and anuran species diversity were tested in the Restinga landscapes of the Parnaíba River delta in northeastern Brazil. Twenty-one anuran species were sampled in the rainy season during monthly excursions (December 2015 to June 2016) into areas of Restinga on two islands in the Parnaíba River delta. The fourth highest anuran diversity was found in this type of environment in Brazil and is the third in northeastern Brazil. Microenvironments, characterized by a combination of vernal pools with different vegetational and physical structures, better explained anuran species composition in the Parnaíba River delta.

Niger Delta Development Commission and Sustainable ...

African Journals Online (AJOL)

Niger Delta Development Commission and Sustainable Development of Niger Delta Region of Nigeria: The Case of Rivers State. Goddey Wilson. Abstract. The study is on Niger Delta Development Commission and sustainable development of Niger Delta region of Nigeria, the case of Rivers State. The main objective of the ...

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

Science.gov (United States)

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.

Inorganic aerosols responses to emission changes in Yangtze River Delta, China.

Science.gov (United States)

Dong, Xinyi; Li, Juan; Fu, Joshua S; Gao, Yang; Huang, Kan; Zhuang, Guoshun

2014-05-15

The new Chinese National Ambient Air Quality standards (CH-NAAQS) published on Feb. 29th, 2012 listed PM2.5 as criteria pollutant for the very first time. In order to probe into PM2.5 pollution over Yangtze River Delta, the integrated MM5/CMAQ modeling system is applied for a full year simulation to examine the PM2.5 concentration and seasonality, and also the inorganic aerosols responses to precursor emission changes. Total PM2.5 concentration over YRD was found to have strong seasonal variation with higher values in winter months (up to 89.9 μg/m(3) in January) and lower values in summer months (down to 28.8 μg/m(3) in July). Inorganic aerosols were found to have substantial contribution to PM2.5 over YRD, ranging from 37.1% in November to 52.8% in May. Nocturnal production of nitrate (NO3(-)) through heterogeneous hydrolysis of N2O5 was found significantly contribute to high NO3(-) concentration throughout the year. In winter, NO3(-) was found to increase under nitrogen oxides (NOx) emission reduction due to higher production of N2O5 from the excessive ozone (O3) introduced by attenuated titration, which further lead to increase of ammonium (NH4(+)) and sulfate (SO4(2-)), while other seasons showed decrease response of NO3(-). Sensitivity responses of NO3(-) under anthropogenic VOC emission reduction was examined and demonstrated that in urban areas over YRD, NO3(-) formation was actually more sensitive to VOC than NOx due to the O3-involved nighttime chemistry of N2O5, while a reduction of NOx emission may have counter-intuitive effect by increasing concentrations of inorganic aerosols. Copyright © 2014 Elsevier B.V. All rights reserved.

An ozone episode over the Pearl River Delta in October 2008

Science.gov (United States)

Shen, Jin; Zhang, Yuanhang; Wang, Xuesong; Li, Jinfeng; Chen, Hao; Liu, Run; Zhong, Liuju; Jiang, Ming; Yue, Dingli; Chen, Duohong; Lv, Wei

2015-12-01

The north and east Pearl River Delta (PRD) is usually a clean, upwind area in autumn. Serious ozone pollution there in mid-late October 2008 was first discovered and then analyzed. Trajectory analysis, process analysis, ozone source apportionment technology, and sensitivity analysis were used to study this episode. Under the influence of a weak south wind, the precursors emitted in Guangzhou and Foshan were transported to the north and northeast PRD and formed ozone there, which resulted in high ozone concentration (>100 ppb). As the wind direction later transited to northerly, the precursors in the northeast PRD that originated from the central and west PRD were transported to the south, and caused severe ozone pollution in the southeast PRD. The ozone contributed by chemical processes reached >20 ppb/h in Jinguowan. More than 40 ppb ozone was contributed by the precursor emission in the central and west PRD during the episode. The ozone concentration was highly sensitive to the precursor emission in the PRD region in the high-ozone situations. This episode showed the complexity of regional pollution in the PRD. When the PRD is controlled by a low air pressure system and then cold air moves from northern China to the south, the risk of ozone pollution in the north and southeast PRD increases.

CMS: LiDAR Data for Mangrove Forests in the Zambezi River Delta, Mozambique, 2014

Data.gov (United States)

National Aeronautics and Space Administration — This data set provides high-resolution LiDAR point cloud data collected during surveys over mangrove forests in the Zambezi River Delta in Mozambique in May 2014....

Tides Stabilize Deltas until Humans Interfere

Science.gov (United States)

Hoitink, T.; Zheng Bing, W.; Vermeulen, B.; Huismans, Y.; Kastner, K.

2017-12-01

Despite global concerns about river delta degradation caused by extraction of natural resources, sediment retention by reservoirs and sea-level rise, human activity in the world's largest deltas intensifies. In this review, we argue that tides tend to stabilize deltas until humans interfere. Under natural circumstances, delta channels subject to tides are more stable than their fluvial-dominated counterparts. The oscillatory tidal flow counteracts the processes responsible for bank erosion, which explains why unprotected tidal channels migrate only slowly. Peak river discharges attenuate the tides, which creates storage space to accommodate the extra river discharge during extreme events and as a consequence, reduce flood risk. With stronger tides, the river discharge is being distributed more evenly over the various branches in a delta, preventing silting up of smaller channels. Human interference in deltas is massive. Storm surge barriers are constructed, new land is being reclaimed and large-scale sand excavation takes place, to collect building material. Evidence from deltas around the globe shows that in human-controlled deltas the tidal motion often plays a destabilizing role. In channels of the Rhine-Meuse Delta, some 100 scour holes are identified, which relates to the altered tidal motion after completion of a storm surge barrier. Sand mining has led to widespread river bank failures in the tidally-influenced Mekong Delta. The catastrophic flood event in the Gauges-Brahmaputra Delta by Cyclone Aila, which caused the inundation of an embanked polder area for over two years, was preceded by river bank erosion at the mouths of formal tidal channels that were blocked by the embankment. Efforts to predict the developments of degrading deltas are few. Existing delta models are capable of reproducing expanding deltas, which is essentially a matter of simulating the transport of sediment from source in a catchment to the sink in a delta. Processes of soil

Environmental flows and its evaluation of restoration effect based on LEDESS model in Yellow River Delta wetlands

NARCIS (Netherlands)

Wang, X.G.; Lian, Y.; Huang, C.; Wang, X.J.; Wang, R.L.; Shan, K.; Pedroli, B.; Eupen, van M.; Elmahdi, A.; Ali, M.

2012-01-01

Due to freshwater supplement scarcity and heavy human activities, the fresh water wetland ecosystem in Yellow River Delta is facing disintegrated deterioration, and it is seriously affecting the health of the Yellow River ecosystem. This paper identifies the restoration objectives of wetland aiming

Hydraulic survey and scour assessment of Bridge 524, Tanana River at Big Delta, Alaska

Science.gov (United States)

Heinrichs, Thomas A.; Langley, Dustin E.; Burrows, Robert L.; Conaway, Jeffrey S.

2007-01-01

Bathymetric and hydraulic data were collected August 26–28, 1996, on the Tanana River at Big Delta, Alaska, at the Richardson Highway bridge and Trans-Alaska Pipeline crossing. Erosion along the right (north) bank of the river between the bridge and the pipeline crossing prompted the data collection. A water-surface profile hydraulic model for the 100- and 500-year recurrence-interval floods was developed using surveyed information. The Delta River enters the Tanana immediately downstream of the highway bridge, causing backwater that extends upstream of the bridge. Four scenarios were considered to simulate the influence of the backwater on flow through the bridge. Contraction and pier scour were computed from model results. Computed values of pier scour were large, but the scour during a flood may actually be less because of mitigating factors. No bank erosion was observed at the time of the survey, a low-flow period. Erosion is likely to occur during intermediate or high flows, but the actual erosion processes are unknown at this time.

Shoreline Changes on the Wave-Influenced Senegal River Delta, West Africa: The Roles of Natural Processes and Human Interventions

OpenAIRE

Sadio , Mamadou; Anthony , Edward ,; Diaw , Amadou ,; DUSSOUILLEZ , Philippe; FLEURY , Jules; Kane , Alioune; Almar , Rafael; Kestenare , Élodie

2017-01-01

International audience; The Senegal River delta in West Africa, one of the finest examples of " wave-influenced " deltas, is bounded by a spit periodically breached by waves, each breach then acting as a shifting mouth of the Senegal River. Using European Re-Analysis (ERA) hindcast wave data from 1984 to 2015 generated by the Wave Atmospheric Model (WAM) of the European Centre for Medium-Range Weather Forecasts (ECMWF), we calculated longshore sediment transport rates along the spit. We also ...

Effects of the proposed California WaterFix North Delta Diversion on survival of juvenile Chinook salmon (Oncorhynchus tshawytscha) in the Sacramento-San Joaquin River Delta, northern California

Science.gov (United States)

Perry, Russell W.; Pope, Adam C.

2018-05-11

The California Department of Water Resources and Bureau of Reclamation propose new water intake facilities on the Sacramento River in northern California that would convey some of the water for export to areas south of the Sacramento-San Joaquin River Delta (hereinafter referred to as the Delta) through tunnels rather than through the Delta. The collection of water intakes, tunnels, pumping facilities, associated structures, and proposed operations are collectively referred to as California WaterFix. The water intake facilities, hereinafter referred to as the North Delta Diversion (NDD), are proposed to be located on the Sacramento River downstream of the city of Sacramento and upstream of the first major river junction where Sutter Slough branches from the Sacramento River. The NDD can divert a maximum discharge of 9,000 cubic feet per second (ft3 /s) from the Sacramento River, which reduces the amount of Sacramento River inflow into the Delta. In this report, we conduct four analyses to investigate the effect of the NDD and its proposed operation on survival of juvenile Chinook salmon (Oncorhynchus tshawytscha). All analyses used the results of a Bayesian survival model that allowed us to simulate travel time, migration routing, and survival of juvenile Chinook salmon migrating through the Delta in response to NDD operations, which affected both inflows to the Delta and operation of the Delta Cross Channel (DCC). For the first analysis, we evaluated the effect of the NDD bypass rules on salmon survival. The NDD bypass rules are a set of operational rule curves designed to provide adaptive levels of fish protection by defining allowable diversion rates as a function of (1) Sacramento River discharge as measured at Freeport, and (2) time of year when endangered runs requiring the most protection are present. We determined that all bypass rule curves except constant low-level pumping (maximum diversion of 900 ft3 /s) could cause a sizeable decrease in survival by as

Mapping Impervious Surface Expansion using Medium-resolution Satellite Image Time Series: A Case Study in the Yangtze River Delta, China

Science.gov (United States)

Gao, Feng; DeColstoun, Eric Brown; Ma, Ronghua; Weng, Qihao; Masek, Jeffrey G.; Chen, Jin; Pan, Yaozhong; Song, Conghe

2012-01-01

Cities have been expanding rapidly worldwide, especially over the past few decades. Mapping the dynamic expansion of impervious surface in both space and time is essential for an improved understanding of the urbanization process, land-cover and land-use change, and their impacts on the environment. Landsat and other medium-resolution satellites provide the necessary spatial details and temporal frequency for mapping impervious surface expansion over the past four decades. Since the US Geological Survey opened the historical record of the Landsat image archive for free access in 2008, the decades-old bottleneck of data limitation has gone. Remote-sensing scientists are now rich with data, and the challenge is how to make best use of this precious resource. In this article, we develop an efficient algorithm to map the continuous expansion of impervious surface using a time series of four decades of medium-resolution satellite images. The algorithm is based on a supervised classification of the time-series image stack using a decision tree. Each imerpervious class represents urbanization starting in a different image. The algorithm also allows us to remove inconsistent training samples because impervious expansion is not reversible during the study period. The objective is to extract a time series of complete and consistent impervious surface maps from a corresponding times series of images collected from multiple sensors, and with a minimal amount of image preprocessing effort. The approach was tested in the lower Yangtze River Delta region, one of the fastest urban growth areas in China. Results from nearly four decades of medium-resolution satellite data from the Landsat Multispectral Scanner (MSS), Thematic Mapper (TM), Enhanced Thematic Mapper plus (ETM+) and China-Brazil Earth Resources Satellite (CBERS) show a consistent urbanization process that is consistent with economic development plans and policies. The time-series impervious spatial extent maps derived

Changes in sediment and organic carbon accumulation in a highly-disturbed ecosystem: The Sacramento-San Joaquin River Delta (California, USA)

International Nuclear Information System (INIS)

Canuel, Elizabeth A.; Lerberg, Elizabeth J.; Dickhut, Rebecca M.; Kuehl, Steven A.; Bianchi, Thomas S.; Wakeham, Stuart G.

2009-01-01

We used the Sacramento-San Joaquin River Delta CA (Delta, hereafter) as a model system for understanding how human activities influence the delivery of sediment and total organic carbon (TOC) over the past 50-60 years. Sediment cores were collected from sites within the Delta representing the Sacramento River (SAC), the San Joaquin River (SJR), and Franks Tract (FT), a flooded agricultural tract. A variety of anthropogenic tracers including 137 Cs, total DDE (ΣDDE) and brominated diphenyl ether (BDE) congeners were used to quantify sediment accumulation rates. This information was combined with total organic carbon (TOC) profiles to quantify rates of TOC accumulation. Across the three sites, sediment and TOC accumulation rates were four to eight-fold higher prior to 1972. Changes in sediment and TOC accumulation were coincident with completion of several large reservoirs and increased agriculture and urbanization in the Delta watershed. Radiocarbon content of TOC indicated that much of the carbon delivered to the Delta is 'pre-aged' reflecting processing in the Delta watershed or during transport to the sites rather than an input of predominantly contemporary carbon (e.g., 900-1400 years BP in surface sediments and 2200 yrs BP and 3610 yrs BP at the base of the SJR and FT cores, respectively). Together, these data suggest that human activities have altered the amount and age of TOC accumulating in the Delta since the 1940s.

A weighted higher-order network analysis of fine particulate matter (PM2.5) transport in Yangtze River Delta

Science.gov (United States)

Wang, Yufang; Wang, Haiyan; Zhang, Shuhua

2018-04-01

Specification of PM2.5 transmission characteristics is important for pollution control, policymaking and prediction. In this paper, we propose weights for motif instances, thereby to implement a weighted higher-order clustering algorithm for a weighted, directed PM2.5 network in the Yangtze River Delta (YRD) of China. The weighted, directed network we create in this paper includes information on meteorological conditions of wind speed and wind direction, plus data on geographic distance and PM2.5 concentrations. We aim to reveal PM2.5 mobility between cities in the YRD. Major potential PM2.5 contributors and closely interacted clusters are identified in the network of 178 air quality stations in the YRD. To our knowledge, it is the first work to incorporate weight information into the higher-order network analysis to study PM2.5 transport.

Source-receptor relationships for PM2.5 during typical pollution episodes in the Pearl River Delta city cluster, China

Science.gov (United States)

Fan, Q.; Liu, Y.; Hong, Y.; Wang, X.; Chan, P.; Chen, X.; Lai, A.; Wang, M.; Chen, X.

2017-12-01

Located in the Southern China monsoon region, pollution days in Pearl River Delta (PRD) were classified into "Western type", "Central type" or "Eastern type", with a relative percentage of 67%, 24% and 9%, respectively. Using this classification system, three typical pollution events were selected for numerical simulations using the WRF-Chem model. The source sensitivity method for anthropogenic emissions of PM2.5 and its precursors was applied to identify the source-receptor relationships for PM2.5 among 9 cities in PRD. For "Western type" case, the PRD region was under control of a high-pressure system with easterly prevailing winds. The PM2.5 concentrations in the western PRD region were higher than those in the eastern region, with emissions from cities in the eastern PRD region having higher contributions. Within the PRD's urban cluster, PM2.5 in Huizhou, Dongguan and Shenzhen was mainly derived from local emissions, whereas the PM2.5 in the other cities was primarily derived from external transport. For "Eastern type" case, the PRD was influenced by Typhoon Soulik with westerly prevailing winds. Emissions from cities in the western PRD region had the highest impacts on the overall PM2.5 concentration. PM2.5 in Jiangmen and Foshan was primarily derived from local emissions. Regarding "Central type" case, the PRD region was under control of a uniform pressure field with low wind speed. PM2.5 concentrations of each city were primarily caused by local emissions. Overall, wind flows played a significant role in the transport and spatial distribution of PM2.5 across the PRD region. Ideally, local governments would be wise to establish joint prevention and control measures to reduce regional atmospheric pollution, especially for "Western type" pollution.

Mechanisms of Sediment Transport to an Abandoned Distributary Channel on the Huanghe (Yellow River) Delta, China

Science.gov (United States)

Kumpf, L. L.; Kineke, G. C.; Carlson, B.; Mullane, M.

2017-12-01

Avulsions on the fine-grained Huanghe delta have left it scarred with traces of abandoned distributary channels that become intertidal systems, open to water and sediment exchange with the sea. In 1996, an engineered avulsion of the Huanghe left a 30 km long abandoned channel to the south of the modern active river channel. Though all fluvial input was cut off, present-day sedimentation on the new tidal flats has been observed at rates around 2 cm/yr. The source must be suspended-sediment from the Bohai Sea conveyed by the tidal channel network, but the mechanisms promoting sediment import are unknown. Possible mechanisms include (A) import sourced from the sediment-rich buoyant coastal plume, (B) wave resuspension on the shallow shelf, (C) reverse-estuarine residual circulation in the tidal channel, and (D) tidal asymmetry in the channel. Over three summers, in situ measurements of current velocity, suspended-sediment concentration (SSC), and wave climate were made on the delta front, and measurements of velocity, SSC, and salinity were made within the tidal channel. Results suggest that the buoyant plume from the active Huanghe channel can transport sediment south toward the tidal channel mouth (A). Additionally, wave resuspension (B) takes place on the subaqueous topset beds when the significant wave height exceeds 1 m, providing potential sources of suspended-sediment to the tidal channel. Within the abandoned channel, the tidal channel can become hypersaline and exhibit reverse-estuarine circulation (C), which would promote import of turbid coastal water near the surface. Time-series of velocity in the tidal channel indicate that ebb currents are consistently higher than flood currents through the spring-neap cycle (D), with maximum velocities exceeding 1 m/s and corresponding maximum SSC reaching 2 g/L during spring tide. While ebb dominance would typically tend to flush the system of its sediment over time, sediment supplied to the tidal flats may not be

Induction of lipids and resultant FAME profiles of microalgae from coastal waters of Pearl River Delta.

Science.gov (United States)

Daroch, Maurycy; Shao, Congcong; Liu, Ying; Geng, Shu; Cheng, Jay J

2013-10-01

This article presents a study on identification, cultivation and characterisation of microalgal strains from the coastal waters of the Pearl River Delta in Guangdong, China. Thirty-seven identified strains belong to the families: Chlorellaceae, Scotiellocystoidaceae, Scenedesmaceae,Selenastraceae,Micractiniaceae, Coccomyxaceae, Trebouxiaceae and Chlorococcaceae. Of isolated strains, Hindakia PKUAC 169 was selected for lipid induction using two methods: nitrogen starvation and salt stress. After derivatisation of algal lipids through in situ transesterification, lipid profiles of the alga under the two methods were analysed. The results have shown that both lipid yield and fatty acid profiles vary with the methods. Of the two tested methods of inducing lipid production, salt stress yielded three-fold higher lipid productivity than nitrogen starvation. The lipids are predominantly composed of C14-C18 fatty acids, which are favourable for biodiesel production. Moreover, the content of polyunsaturated fatty acids was below the limit of 12% set by EN14214 biodiesel standard. Copyright © 2013 Elsevier Ltd. All rights reserved.

Erosion of the Mekong delta: the role of human activities

Science.gov (United States)

Anthony, E.; Dussouillez, P.; Goichot, M.; Brunier, G.; Dolique, F.; Nguyen, V.; Loisel, H.; Mangin, A.; Vantrepotte, V.

2013-12-01

River deltas are threatened by dams, dykes, flow channelling, and aggregate extraction. These activities outweigh climate change and sea-level rise in causing delta vulnerability1, and will aggravate the impacts to be expected from these effects2. We show here from analysis of: (1) delta channel morphology and sediment budgets, and (2) satellite imagery, that the Mekong delta, considered as the world's third largest, and hitherto strongly prograding, is now in a phase of large-scale erosion. We discuss the mechanistic links involved in erosion and the way these are related to human activities. High-resolution (2.5 m) SPOT 5 images for the years 2003, 2007, 2011/12 covering 405 km of the delta shoreline show an overall retreat rate of over 8 m a year. 75% of the analysed shoreline, i.e., the muddy western sector, is now retreating at rates exceeding 50 m a year in places. The sandy river-mouth sector maintains a semblance of stability, but with strong variations. We attribute erosion to a cascade of morphosedimentary changes linked to sediment mining from the deltaic channels and upstream dam interception. We estimated from Meris satellite imagery an annual 5% decrease in surface suspended concentrations exiting at the mouths of the Mekong over the period 2003-2011 that may reflect increased trapping of mud behind dams in China. We also infer modification of river-mouth and coastal mud storage patterns resulting from a loss of ca. 200 million m3 of delta channel sediments between 1998 and 2008 from aggregate extraction. Dykes have been shown to result in increased channel flow velocities during the high-discharge monsoon season, favouring further channel deepening3. Stronger river-mouth outflow velocities during this season may be leading to export of a greater proportion of mud far offshore of the coastal longshore transport corridor that ensured mud supply to, and past progradation of, the muddy western coast. In contrast, greater seawater penetration in the

DEVELOPMENT ELECTRONIC MAPS OF ECOLOGICAL STATUS OF WATER OBJECTS OF THE VOLGA RIVER DELTA

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Z. N. Isenalieva

2016-01-01

Full Text Available Abstract. Aim. The aim of this work was the comprehensive study of the ecological state of water objects of the Volga River delta. Methods. The following methods were used: field (collection, observation, organoleptic, uniform chemical analysis techniques are based on colorimetric, settlement, photometric, spectrometric measurement methods. Results. On the basis of results of researches for 2010-2014 performed a comparative analysis of the dynamics of the content of hydro-chemical indicators of environmental quality in waters of the Volga River delta and the residential areas of the background. Applying an integrated approach to the study of biological indicators of water quality. Created digitized map of the quality of aquatic ecosystems of the Volga River delta. Displaying modern ecological condition of watercourses investigated, determined the degree of contamination, the overall trophic and saprobic. Main conclusions. The work has identified adverse environmental situation in water objects of the Astrakhan and the surrounding areas. Average annual concentrations of toxicological substances water objects in the background zone 10 times less than in the water objects of settlements. As a result of work on the basis of ArcGis 10.2.2 created information environment "Eco-monitor", which is a systematic set of information, and quantitatively characterizing the ecological status of water objects. Created on the basis of ArcGis 10.2.2 information environment monitoring system of waterways allows for a temporary and spatial analysis, to assess the quality of different streams in the control sections.

Relevance of the Paraná River hydrology on the fluvial water quality of the Delta Biosphere Reserve.

Science.gov (United States)

Puig, Alba; Olguín Salinas, Héctor F; Borús, Juan A

2016-06-01

The increasing frequency of extreme events in large rivers may affect not only their flow, but also their water quality. In the present study, spatial and temporal changes in fluvial physico-chemical variables were analyzed in a mega-river delta during two extreme hydrological years (La Niña-El Niño) and related to potential explanatory factors. Basic water variables were evaluated in situ at 13 points (distant 2-35 km from each other) in watercourses of the Delta Biosphere Reserve (890 km(2)) in the Lower Paraná River (Argentina) in nine surveys (October 2008-July 2010) without meteorological tides. Samples for laboratory analyses were collected from each main river. Multivariate tests by permutations were applied. The period studied was influenced by a drought, within a long period dominated by low flows combined with dry weather and wildfires, and a large (10 years of recurrence) and prolonged (7 months) flood. The hydrological phase, followed by the season and the hydrological year (according to the ENSO event) were the principal explanatory factors of the main water quality changes, whereas the drainage sub-basin and the fluvial environment (river or stream) were secondary explanatory factors. During the drought period, conductivity, turbidity, and associated variables (e.g., major ions, silicon, and iron concentrations) were maximal, whereas real color was minimal. In the overbanking flood phase, pH and dissolved oxygen concentration were minimal, whereas real color was maximal. Dissolved oxygen saturation was also low in the receding flood phase and total major ion load doubled after the arrival of the overbanking stage. The water quality of these watercourses may be affected by the combination of several influences, such as the Paraná River flow, the pulses with sediments and solutes from the Bermejo River, the export of the Delta floodplain properties mainly by the flood, the season, and the saline tributaries to the Lower Paraná River. The high

Ecology of Juvenile Salmon in Shallow Tidal Freshwater Habitats in the Vicinity of the Sandy River Delta, Lower Columbia River, 2008 Annual Report.

Energy Technology Data Exchange (ETDEWEB)

Sather, NK; Johnson, GE; Storch, AJ [Pacific Northwest National Laboratory

2009-07-06

The tidal freshwater monitoring (TFM) project reported herein is part of the research, monitoring, and evaluation effort developed by the Action Agencies (Bonneville Power Administration, the U.S. Army Corps of Engineers [USACE], and the U.S. Bureau of Reclamation) in response to obligations arising from the Endangered Species Act (ESA) as a result of operation of the Federal Columbia River Power System. The project is being performed under the auspices of the Northwest Power and Conservation Council's Columbia Basin Fish and Wildlife Program (Project No. 2005-001-00). The research is a collaborative effort among the Pacific Northwest National Laboratory, the Oregon Department of Fish and Wildlife, the National Marine Fisheries Service, and the University of Washington. The overarching goal of the TFM project is to bridge the gap in knowledge between tidal freshwater habitats and the early life history attributes of migrating salmon. The research questions include: In what types of habitats within the tidal freshwater area of the Columbia River are juvenile salmon found, when are they present, and under what environmental conditions? What is the ecological contribution of shallow (0-5 m) tidal freshwater habitats to the recovery of ESA-listed salmon in the Columbia River basin? Field data collection for the TFM project commenced in June 2007 and since then has continued monthly at six to nine sites in the vicinity of the Sandy River delta (river kilometer 192-208). While this report includes summary data spanning the 19-month period of study from June 2007 through December 2008, it highlights sampling conducted during calendar year 2008. Detailed data for calendar year 2007 were reported previously. The 2008 research objectives were as follows: (1) Characterize the vegetation composition and percent cover, conventional water quality, water surface elevation, substrate composition, bathymetry, and beach slope at the study sites within the vicinity of the Sandy

Distribution and Joint Fish-Tag Survival of Juvenile Chinook Salmon Migrating through the Sacramento-San Joaquin River Delta, California, 2008

Science.gov (United States)

Holbrook, Christopher M.; Perry, Russell W.; Adams, Noah S.

2009-01-01

Acoustic telemetry was used to obtain the movement histories of 915 juvenile fall-run Chinook salmon (Oncorhynchus tshawytscha) through the lower San Joaquin River and Sacramento-San Joaquin Delta, California, in 2008. Data were analyzed within a release-recapture framework to estimate survival, route distribution, and detection probabilities among three migration pathways through the Delta. The pathways included the primary route through the San Joaquin River and two less direct routes (Old River and Turner Cut). Strong inferences about survival were limited by premature tag failure, but estimates of fish distribution among migration routes should be unaffected by tag failure. Based on tag failure tests (N = 66 tags), we estimated that only 55-78 percent of the tags used in this study were still functioning when the last fish was detected exiting the study area 15 days after release. Due to premature tag failure, our 'survival' estimates represent the joint probability that both the tag and fish survived, not just survival of fish. Low estimates of fish-tag survival could have been caused by fish mortality or fish travel times that exceeded the life of the tag, but we were unable to differentiate between the two. Fish-tag survival through the Delta (from Durham Ferry to Chipps Island by all routes) ranged from 0.05 +or- 0.01 (SE) to 0.06 +or- 0.01 between the two weekly release groups. Among the three migration routes, fish that remained in the San Joaquin River exhibited the highest joint fish-tag survival (0.09 +or- 0.02) in both weeks, but only 22-33 percent of tagged fish used this route, depending on the week of release. Only 4-10 percent (depending on week) of tagged fish traveled through Turner Cut, but no tagged fish that used this route were detected exiting the Delta. Most fish (63-68 percent, depending on week of release) migrated through Old River, but fish-tag survival through this route (0.05 +or- 0.01) was only about one-half that of fish that

A survey of sport fish use on the Copper River Delta, Alaska.

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Dirk W. Lang

2010-01-01

Aerial counts, in-person interviews, and mail-in questionnaires were used to survey sport fish use during the coho salmon (Oncorhynchus kisutch Walbaum) season on the Copper River Delta, Alaska from 2002 through 2006. Angler counts provided an index of use on individual streams and were used to develop a spatial database exhibiting patterns of use...

Landscape controls and vertical variability of soil organic carbon storage in permafrost-affected soils of the Lena River Delta

DEFF Research Database (Denmark)

Siewert, Matthias Benjamin; Hugelius, Gustaf; Heim, Birgit

2016-01-01

To project the future development of the soil organic carbon (SOC) storage in permafrost environments, the spatial and vertical distribution of key soil properties and their landscape controls needs to be understood. This article reports findings from the Arctic Lena River Delta where we sampled 50...... in the permafrost. The major geomorphological units of a subregion of the Lena River Delta were mapped with a land form classification using a data-fusion approach of optical satellite imagery and digital elevation data to upscale SOC storage. Landscape mean SOC storage is estimated to 19.2 ± 2.0 kg C m− 2. Our...... results show that the geomorphological setting explains more soil variability than soil taxonomy classes or vegetation cover. The soils from the oldest, Pleistocene aged, unit of the delta store the highest amount of SOC per m2 followed by the Holocene river terrace. The Pleistocene terrace affected...

Impacts of the dam-orientated water-sediment regulation scheme on the lower reaches and delta of the Yellow River (Huanghe): A review

Science.gov (United States)

Wang, Houjie; Wu, Xiao; Bi, Naishuang; Li, Song; Yuan, Ping; Wang, Aimei; Syvitski, James P. M.; Saito, Yoshiki; Yang, Zuosheng; Liu, Sumei; Nittrouer, Jeffrey

2017-10-01

The water-sediment regulation scheme (WSRS), beginning in 2002, is an unprecedented engineering effort to manage the Yellow River with the aims to mitigate the siltation both in the lower river channel and within the Xiaolangdi Reservoir utilizing the dam-regulated flood water. Ten years after its initial implementation, multi-disciplinary indicators allow us to offer a comprehensive review of this human intervention on a river-coastal system. The WSRS generally achieved its objective, including bed erosion in the lower reaches with increasing capacity for flood discharge and the mitigation of reservoir siltation. However, the WSRS presented unexpected disturbances on the delta and coastal system. Increasing grain size of suspended sediment and decreasing suspended sediment concentration at the river mouth resulted in a regime shift of sediment transport patterns that enhanced the disequilibrium of the delta. The WSRS induced an impulse delivery of nutrients and pollutants within a short period ( 20 days), which together with the altered hydrological cycle, impacted the estuarine and coastal ecosystem. We expect that the sediment yield from the loess region in the future will decrease due to soil-conservation practices, and the lower channel erosion will also decrease as the riverbed armors with coarser sediment. These, in combination with uncertain water discharge concomitant with climate change, increasing water demands and delta subsidence, will put the delta and coastal ocean at high environmental risks. In the context of global change, this work depicts a scenario of human impacts in the river basin that were transferred along the hydrological pathway to the coastal system and remotely transformed the different components of coastal environment. The synthesis review of the WSRS indicates that an integrated management of the river-coast continuum is crucially important for the sustainability of the entire river-delta system. The lessons learned from the WSRS in

Assessment of transboundary environmental effects in the Pearl River Delta Region: Is there a role for strategic environmental assessment?

International Nuclear Information System (INIS)

Marsden, Simon

2011-01-01

China's EIA Law does not require transboundary proposals to be assessed, despite recognition of this globally, for example in the Espoo Convention and Kiev Protocol, and in the European EIA and SEA Directives. In a transboundary context assessment within a state is unusual, as regulating these effects is primarily about the relationship between states. However where a state has more than one legal system such as in the Pearl River Delta (PRD) Region of southern China, transboundary effects should also be addressed. Yet despite the geographical connections between Guangdong Province in mainland China (where the EIA Law applies) and the Hong Kong and Macau Special Administrative Regions (which have their own provisions, neither of which requires transboundary assessments), EIA and SEA are carried out separately. Coordinated or joint approaches to transboundary assessment are generally absent, with the legal autonomy of Hong Kong and Macau a major constraint. As a result institutional responses at the policy level have developed. The article considers global experiences with regulating transboundary EIA and SEA, and analyses potential application to land use, transport and air and water planning in the PRD Region. If applied, benefits may include prevention or mitigation of cumulative effects, broader public participation, and improvements to environmental governance. The PRD Region experience may encourage China to conduct and coordinate EIA and SEA processes with neighbouring states, which has been non-existent or extremely limited to date.

Ecology of Juvenile Salmonids in Shallow Tidal Freshwater Habitats in the Vicinity of the Sandy River Delta, Lower Columbia River, 2007 Annual Report.

Energy Technology Data Exchange (ETDEWEB)

Sobocinski, Kathryn; Johnson, Gary; Sather, Nichole [Pacific Northwest National Laboratory

2008-03-17

This document is the first annual report for the study titled 'Ecology of Juvenile Salmonids in Shallow Tidal Freshwater Habitats in the Vicinity of the Sandy River Delta in the Lower Columbia River'. Hereafter, we refer to this research as the Tidal Freshwater Monitoring (TFM) Study. The study is part of the research, monitoring, and evaluation effort developed by the Action Agencies (Bonneville Power Administration, U.S. Army Corps of Engineers, U.S. Bureau of Reclamation) in response to obligations arising from the Endangered Species Act as a result of operation of the Federal Columbia River Power System (FCRPS). The project is performed under the auspices of the Northwest Power and Conservation Council's Columbia Basin Fish and Wildlife Program. The goal of the 2007-2009 Tidal Freshwater Monitoring Study is to answer the following questions: In what types of habitats within the tidal freshwater area of the lower Columbia River and estuary (LCRE; Figure 1) are yearling and subyearling salmonids found, when are they present, and under what environmental conditions?1 And, what is the ecological importance2 of shallow (0-5 m) tidal freshwater habitats to the recovery of Upper Columbia River spring Chinook salmon and steelhead and Snake River fall Chinook salmon? Research in 2007 focused mainly on the first question, with fish stock identification data providing some indication of Chinook salmon presence at the variety of habitat types sampled. The objectives and sub-objectives for the 2007 study were as follows: (1) Habitat and Fish Community Characteristics-Provide basic data on habitat and fish community characteristics for yearling and subyearling salmonids at selected sites in the tidal freshwater reach in the vicinity of the Sandy River delta. (1a) Characterize vegetation assemblage percent cover, conventional water quality, substrate composition, and beach slope at each of six sampling sites in various tidal freshwater habitat types. (1b

Emission inventory of anthropogenic air pollutants and VOC species in the Yangtze River Delta region, China

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C. Huang

2011-05-01

Full Text Available The purpose of this study is to develop an emission inventory for major anthropogenic air pollutants and VOC species in the Yangtze River Delta (YRD region for the year 2007. A "bottom-up" methodology was adopted to compile the inventory based on major emission sources in the sixteen cities of this region. Results show that the emissions of SO₂, NO_x, CO, PM₁₀, PM_2.5, VOCs, and NH₃ in the YRD region for the year 2007 are 2392 kt, 2293 kt, 6697 kt, 3116 kt, 1511 kt, 2767 kt, and 459 kt, respectively. Ethylene, mp-xylene, o-xylene, toluene, 1,2,4-trimethylbenzene, 2,4-dimethylpentane, ethyl benzene, propylene, 1-pentene, and isoprene are the key species contributing 77 % to the total ozone formation potential (OFP. The spatial distribution of the emissions shows the emissions and OFPs are mainly concentrated in the urban and industrial areas along the Yangtze River and around Hangzhou Bay. The industrial sources, including power plants other fuel combustion facilities, and non-combustion processes contribute about 97 %, 86 %, 89 %, 91 %, and 69 % of the total SO₂, NO_x, PM₁₀, PM_2.5, and VOC emissions. Vehicles take up 12.3 % and 12.4 % of the NO_x and VOC emissions, respectively. Regarding OFPs, the chemical industry, domestic use of paint & printing, and gasoline vehicles contribute 38 %, 24 %, and 12 % to the ozone formation in the YRD region.

Cryostratigraphy, sedimentology, and the late Quaternary evolution of the Zackenberg River delta, northeast Greenland

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G. L. Gilbert

2017-05-01

Full Text Available The Zackenberg River delta is located in northeast Greenland (74°30′ N, 20°30′ E at the outlet of the Zackenberg fjord valley. The fjord-valley fill consists of a series of terraced deltaic deposits (ca. 2 km2 formed during relative sea-level (RSL fall. We investigated the deposits using sedimentological and cryostratigraphic techniques together with optically stimulated luminescence (OSL dating. We identify four facies associations in sections (4 to 22 m in height exposed along the modern Zackenberg River and coast. Facies associations relate to (I overriding glaciers, (II retreating glaciers and quiescent glaciomarine conditions, (III delta progradation in a fjord valley, and (IV fluvial activity and niveo-aeolian processes. Pore, layered, and suspended cryofacies are identified in two 20 m deep ice-bonded sediment cores. The cryofacies distribution, together with low overall ground-ice content, indicates that permafrost is predominately epigenetic in these deposits. Fourteen OSL ages constrain the deposition of the cored deposits to between approximately 13 and 11 ka, immediately following deglaciation. The timing of permafrost aggradation was closely related to delta progradation and began following the subaerial exposure of the delta plain (ca. 11 ka. Our results reveal information concerning the interplay between deglaciation, RSL change, sedimentation, permafrost aggradation, and the timing of these events. These findings have implications for the timing and mode of permafrost aggradation in other fjord valleys in northeast Greenland.

Cryostratigraphy, sedimentology, and the late Quaternary evolution of the Zackenberg River delta, northeast Greenland

Science.gov (United States)

Gilbert, Graham L.; Cable, Stefanie; Thiel, Christine; Christiansen, Hanne H.; Elberling, Bo

2017-05-01

The Zackenberg River delta is located in northeast Greenland (74°30' N, 20°30' E) at the outlet of the Zackenberg fjord valley. The fjord-valley fill consists of a series of terraced deltaic deposits (ca. 2 km2) formed during relative sea-level (RSL) fall. We investigated the deposits using sedimentological and cryostratigraphic techniques together with optically stimulated luminescence (OSL) dating. We identify four facies associations in sections (4 to 22 m in height) exposed along the modern Zackenberg River and coast. Facies associations relate to (I) overriding glaciers, (II) retreating glaciers and quiescent glaciomarine conditions, (III) delta progradation in a fjord valley, and (IV) fluvial activity and niveo-aeolian processes. Pore, layered, and suspended cryofacies are identified in two 20 m deep ice-bonded sediment cores. The cryofacies distribution, together with low overall ground-ice content, indicates that permafrost is predominately epigenetic in these deposits. Fourteen OSL ages constrain the deposition of the cored deposits to between approximately 13 and 11 ka, immediately following deglaciation. The timing of permafrost aggradation was closely related to delta progradation and began following the subaerial exposure of the delta plain (ca. 11 ka). Our results reveal information concerning the interplay between deglaciation, RSL change, sedimentation, permafrost aggradation, and the timing of these events. These findings have implications for the timing and mode of permafrost aggradation in other fjord valleys in northeast Greenland.

Accessing the Impact of Sea-Salt Emissions on Aerosol Chemical Formation and Deposition Over Pearl River Delta, China

Science.gov (United States)

Fan, Q.; Wang, X.; Liu, Y.; Wu, D.; Chan, P. W.; Fan, S.; Feng, Y.

2015-12-01

Sea-salt aerosol (SSA) emissions have a significant impact on aerosol pollution and haze formation in the coastal areas. In this study, Models-3/CMAQ modeling system was utilized to access the impact of SSA emissions on aerosol chemical formation and deposition over Pearl River Delta (PRD), China in July 2006. More SSAs were transported inland from the open-ocean under the southeast wind in summertime. Two experiments (with and without SSA emissions in the CMAQ model) were set up to compare the modeling results with each other. The results showed that the increase of sulfate concentrations were more attributable to the primary emissions of coarse SO42- particles in SSA, while the increase of nitrate concentrations were more attributable to secondary chemical formations, known as the mechanisms of chloride depletion in SSA. In the coastal areas, 17.62 % of SO42-, 26.6% of NO3- and 38.2% of PM10 were attributed to SSA emissions, while those portions were less than 1% in the inland areas. The increases of PM10 and its components due to SSA emissions resulted in higher deposition fluxes over PRD, particularly in the coastal areas, except for the wet deposition of nitrate. Nitrate was more sensitive to SSA emissions in chemical formations than sulfate and dry deposition of aerosol was also more sensitive than that for wet deposition. Process analysis of sulfate and nitrate was applied to find out the difference of physical and chemical mechanisms between Guangzhou (the inland areas) and Zhuhai (the coastal areas). The negative contributions of dry deposition process to both sulfate and nitrate concentrations increased if SSA emissions were taken into account in the model, especially for Zhuhai. The negative contributions of cloud process also increased due to cloud scavenging and wet deposition process. In the coastal area, the gas-to-particle conversions became more active with high contributions of aerosol process to nitrate concentrations.

Holocene evolution of a wave-dominated fan-delta: Godavari delta, India

Science.gov (United States)

Saito, Y.; Nageswara Rao, K.; Nagakumar, K.; Demudu, G.; Rajawat, A.; Kubo, S.; Li, Z.

2013-12-01

The Godavari delta is one of the world's largest wave-dominated deltas. The Godavari River arises in the Western Ghats near the west coast of India and drains an area of about 3.1x10^5 km^2, flowing about 1465 km southeast across the Indian peninsula to the Bay of Bengal. The Godavari delta consists of a gentle seaward slope from its apex (12 m elevation) at Rajahmundry and a coastal beach-ridge plain over a distance of about 75 km and covers ~5200 km^2 as a delta plain. The river splits into two major distributary channels, the Gautami and the Vasishta, at a barrage constructed in the mid-1800s. The coastal environment of the deltaic coast is microtidal (~1 m mean tidal range) and wave-dominated (~1.5 m mean wave height in the June-September SW monsoon season, ~0.8 m in the NE monsoon season). Models of the Holocene evolution of the Godavari delta have changed from a zonal progradation model (e.g. Nageswara Rao & Sadakata, 1993) to a truncated cuspate delta model (Nageswara Rao et al., 2005, 2012). Twelve borehole cores (340 m total length), taken in the coastal delta plain during 2010-2013, yielded more than 100 C-14 dates. Sediment facies and C-14 dates from these and previous cores and remote-sensing data support a new delta evolution model. The Holocene coastal delta plain is divided into two parts by a set of linear beach ridges 12-14 km landward from the present shoreline in the central part of the delta. The location of the main depocenter (lobe) has shifted during the Holocene from 1) the center to 2) the west, 3) east, 4) center, 5) west, and 6) east. The linear beach ridges separate the first three from the last three stages. These lobe shifts are controlled by river channel shifts near the apex. Just as the current linear shoreline of the central part of the delta and the concave-up nearshore topography are the result of coastal erosion of a cuspate delta, the linear beach ridges indicate a former eroded shoreline. An unconformity within the deltaic

Trade-Induced Atmospheric Mercury Deposition over China and Implications for Demand-Side Controls.

Science.gov (United States)

Chen, Long; Meng, Jing; Liang, Sai; Zhang, Haoran; Zhang, Wei; Liu, Maodian; Tong, Yindong; Wang, Huanhuan; Wang, Wei; Wang, Xuejun; Shu, Jiong

2018-02-20

Mercury (Hg) is of global concern because of its adverse effects on humans and the environment. In addition to long-range atmospheric transport, Hg emissions can be geographically relocated through economic trade. Here, we investigate the effect of China's interregional trade on atmospheric Hg deposition over China, using an atmospheric transport model and multiregional input-output analysis. In general, total atmospheric Hg deposition over China is 408.8 Mg yr -1 , and 32% of this is embodied in China's interregional trade, with the hotspots occurring over Gansu, Henan, Hebei, and Yunnan provinces. Interprovincial trade considerably redistributes atmospheric Hg deposition over China, with a range in deposition flux from -104% to +28%. Developed regions, such as the Yangtze River Delta (Shanghai, Jiangsu, and Zhejiang) and Guangdong, avoid Hg deposition over their geographical boundaries, instead causing additional Hg deposition over developing provinces. Bilateral interaction among provinces is strong over some regions, suggesting a need for joint mitigation, such as the Jing-Jin-Ji region (Beijing, Tianjin, and Hebei) and the Yangtze River Delta. Transferring advanced technology from developed regions to their developing trade partners would be an effective measure to mitigate China's Hg pollution. Our findings are relevant to interprovincial efforts to reduce trans-boundary Hg pollution in China.

Trace gases, aerosols and their interactions with synoptic weather: An overview of in-situ measurements at the SORPES Station in the western Yangtze River Delta, China

Science.gov (United States)

Ding, A.; Fu, C.; Yang, X.; Petaja, T.; Kerminen, V.; Kulmala, M. T.

2013-12-01

This work presents an overview of 1 yr measurements of ozone (O3) and fine particular matter (PM2.5) and related trace gases at a recently developed regional background site, the Station for Observing Regional Processes of the Earth System (SORPES), in the western part of the Yangtze River Delta (YRD) in eastern China. Ozone and PM2.5 showed strong seasonal cycles but with contrast patterns: O3 reached a maximum in warm seasons but PM2.5 in cold seasons. Correlation analysis suggests a VOC-sensitive regime for O3 chemistry and a formation of secondary aerosols under conditions of high O3 in summer. Compared with the National Ambient Air Quality Standards in China, our measurements report 15 days of O3 exceedance and 148 days of PM2.5 exceedance during the 1 yr period, suggesting a severe air pollution situation in this region. A calculation of potential source contributions based on Lagrangian dispersion simulations suggests that emissions from the YRD contributed to over 70% of the O3 precursor CO, with a majority from the mid-YRD. North-YRD and the North China Plain are the main contributors to PM2.5pollution in this region. Case studies for typical O3 and PM2.5 episodes showed that synoptic weather played an important role in air pollution, especially for O3. Observation during the typical biomass burning seasons also shows clear air pollution - weather interactions. For the typical episode occurred on 10 June, 2012, the measurement suggest that the mixed agricultural burning plumes with fossil fuel combustion pollution resulted in a decrease of solar radiation by more than 70 %, of sensible heat flux over 85 %, a temperature drop by almost 10 K, and a change 10 of rainfall during daytime and nighttime. This work shows an important environmental impact from industrialization and urbanization in the YRD region, and suggests an urgent need for improving air quality in these areas through collaborative control measures among different administrative regions, and

Suitability of river delta sediment as proppant, Missouri and Niobrara Rivers, Nebraska and South Dakota, 2015

Science.gov (United States)

Zelt, Ronald B.; Hobza, Christopher M.; Burton, Bethany L.; Schaepe, Nathaniel J.; Piatak, Nadine

2017-11-16

Sediment management is a challenge faced by reservoir managers who have several potential options, including dredging, for mitigation of storage capacity lost to sedimentation. As sediment is removed from reservoir storage, potential use of the sediment for socioeconomic or ecological benefit could potentially defray some costs of its removal. Rivers that transport a sandy sediment load will deposit the sand load along a reservoir-headwaters reach where the current of the river slackens progressively as its bed approaches and then descends below the reservoir water level. Given a rare combination of factors, a reservoir deposit of alluvial sand has potential to be suitable for use as proppant for hydraulic fracturing in unconventional oil and gas development. In 2015, the U.S. Geological Survey began a program of researching potential sources of proppant sand from reservoirs, with an initial focus on the Missouri River subbasins that receive sand loads from the Nebraska Sand Hills. This report documents the methods and results of assessments of the suitability of river delta sediment as proppant for a pilot study area in the delta headwaters of Lewis and Clark Lake, Nebraska and South Dakota. Results from surface-geophysical surveys of electrical resistivity guided borings to collect 3.7-meter long cores at 25 sites on delta sandbars using the direct-push method to recover duplicate, 3.8-centimeter-diameter cores in April 2015. In addition, the U.S. Geological Survey collected samples of upstream sand sources in the lower Niobrara River valley.At the laboratory, samples were dried, weighed, washed, dried, and weighed again. Exploratory analysis of natural sand for determining its suitability as a proppant involved application of a modified subset of the standard protocols known as American Petroleum Institute (API) Recommended Practice (RP) 19C. The RP19C methods were not intended for exploration-stage evaluation of raw materials. Results for the washed samples are

Water-soluble ions in atmospheric aerosols measured in five sites in the Yangtze River Delta, China: Size-fractionated, seasonal variations and sources

Science.gov (United States)

Wang, Honglei; Zhu, Bin; Shen, Lijuan; Xu, Honghui; An, Junlin; Xue, Guoqiang; Cao, Jinfei

2015-12-01

In order to investigate the regional variations of water-soluble ions (WSIs), size-resolved measurement of aerosol particles and WSIs was conducted by using Anderson Sampler and Ion Chromatography at five sites (Nanjing, Suzhou, Lin'an, Hangzhou and Ningbo) in the Yangtze River Delta (YRD) region, China in the Autumn of 2012 and Winter, Spring and Summer of 2013. WSIs exhibited obvious seasonal variations due to the monsoon conversion, with the highest level in winter and lowest level in summer. The aerosol mass concentrations and WSIs in different size segments varied with four seasons. The dominant ions concentrations in PM2.1 ranked in the order of SO42- > NO3- > NH4+ > Cl- > K+ > Ca2+, and the dominant ions concentrations in PM2.1-10 ranked in the order of Ca2+ > NO3- > SO42- > Cl- > NH4+ > Na+. The size spectra of mass and WSIs concentration peaked mostly at 0.43-0.65 μm in four seasons. The concentration discrepancies of WSIs in different cities were caused by the geographic locations and emission source. It's belonged to ammonium-rich distribution in PM2.1 and ammonium-poor distribution in PM2.1-10 in the YRD region. The impact of temperature on mass concentrations of NO3- and NH4+ in PM2.1 were stronger than those in PM2.1-10. PCA analysis shows that the sources of WSIs dominant by anthropogenic sources, soil particles or falling dust, sea salt and burning process.

Assessing Urban Sustainability Using a Multi-Scale, Theme-Based Indicator Framework: A Case Study of the Yangtze River Delta Region, China

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Cheng Li

2017-11-01

Full Text Available Urban sustainability is a great concern worldwide. However, how to evaluate urban sustainability is still a big challenge because sustainable development is multifaceted and scale dependent, which demands various assessment methods and indicators that often do not reach a consensus. In this study, we assessed urban sustainability of the Yangtze River Delta (YRD, China during 2000–2014 at two spatial scales (corresponding to the administrative levels of province and prefecture. A theme-based indicator framework, cluster analysis and Mann–Kendall test were used for urban sustainability assessment. Our results showed that the overall (OS, social (SS, and economic sustainability (EcS scores for two provinces and sixteen prefectural cities increased from 2000 to 2014 in general, but the environmental sustainability (EnS scores decreased over time. According to the performance of SS, EnS and EcS at the prefectural level, three distinct city clusters were identified: Cluster 1 with high SS and EcS but low EnS; Cluster 2 with low SS and EcS but high EnS; and Cluster 3 with moderate SS, EnS and EcS. The three sustainability dimensions—society, environment and economy—all changed over time and differed among cities at the two administrative levels. Our results implied that, according to the “strong sustainability” perspective, the cities of the YRD became less sustainable or unsustainable because the social and economic progresses were at the expense of the environment. The level of urban sustainability was lower at the provincial level than the prefectural level, implying that the problems of unsustainability are even greater at the provincial level than the prefectural level in the YRD region.

The Colorado river delta (Mexico: ecological importance and management = O delta do rio Colorado (Mexico: importância ecológica e gerenciamento

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José Luis Fermán Almada

2008-10-01

Full Text Available The Colorado river delta is a unique coastal system in the world, as it combines two important systems: the Colorado river and the Gulf of California. Consequently, the delta is dominated by bilateral interests, and influenced by administrative, political and natural processes, which involve the countries of the United States and Mexico. Located in the northern part of the Gulf of California, under a condition of natural isolation, a series of environmental attributeshave been developed (biotic and abiotic that are only observed in is region. In this work, the development of the bilateral political relations and the most important ecological characteristicsare presented, as well as the management instruments that have been developed for over 80 years. From these issues, the possible scenario for the region is defined, and the development of methodologies for monitoring the effects of these possible tendencies on the natural components of the delta is proposed.O delta do rio Colorado é uma zona costeira única em todo o mundo, porassociar dois importantes sistemas: o próprio rio Colorado e o Golfo da Califórnia. Conseqüentemente, o delta é dominado por interesses bi-nacionais e influenciado por processos administrativos, políticos e naturais, envolvendo os Estados Unidos e o México. Localizado no norte do Golfo da Califórnia, sob uma condição de isolamento natural,desenvolveu-se uma série de atributos ambientais (bióticos e abióticos que só podem ser vistos nessa região. Neste trabalho, são apresentados o desenvolvimento das relações políticas bilaterais e as características ecológicas mais importantes, bem como osmecanismos de gerenciamento que vêm sido desenvolvidos por mais de 80 anos. A partir dessas questões, é definido um cenário tendencial possível para a região, e o desenvolvimento de metodologias para o acompanhamento dos efeitos dessas possíveis tendências sobre os componentes naturais do delta é proposto.

Assessment of regional air quality resulting from emission control in the Pearl River Delta region, southern China.

Science.gov (United States)

Wang, N; Lyu, X P; Deng, X J; Guo, H; Deng, T; Li, Y; Yin, C Q; Li, F; Wang, S Q

2016-12-15

To evaluate the impact of emission control measures on the air quality in the Pearl River Delta (PRD) region of South China, statistic data including atmospheric observations, emissions and energy consumptions during 2006-2014 were analyzed, and a Weather Research and Forecasting - Community Multi-scale Air Quality (WRF-CMAQ) model was used for various scenario simulations. Although energy consumption doubled from 2004 to 2014 and vehicle number significantly increased from 2006 to 2014, ambient SO 2 , NO 2 and PM 10 were reduced by 66%, 20% and 24%, respectively, mainly due to emissions control efforts. In contrast, O 3 increased by 19%. Model simulations of three emission control scenarios, including a baseline (a case in 2010), a CAP (a case in 2020 assuming control strength followed past control tendency) and a REF (a case in 2020 referring to the strict control measures based on recent policy/plans) were conducted to investigate the variations of air pollutants to the changes in NO x , VOCs and NH 3 emissions. Although the area mean concentrations of NO x , nitrate and PM 2.5 decreased under both NO x CAP (reduced by 1.8%, 0.7% and 0.2%, respectively) and NO x REF (reduced by 7.2%, 1.8% and 0.3%, respectively), a rising of PM 2.5 was found in certain areas as reducing NO x emissions elevated the atmospheric oxidizability. Furthermore, scenarios with NH 3 emission reductions showed that nitrate was sensitive to NH 3 emissions, with decreasing percentages of 0-10.6% and 0-48% under CAP and REF, respectively. Controlling emissions of VOCs reduced PM 2.5 in the southwestern PRD where severe photochemical pollution frequently occurred. It was also found that O 3 formation in PRD was generally VOCs-limited while turned to be NO x -limited in the afternoon (13:00-17:00), suggesting that cutting VOCs emissions would reduce the overall O 3 concentrations while mitigating NO x emissions in the afternoon could reduce the peak O 3 levels. Copyright © 2016 Elsevier B

[Microbial community in nitrogen cycle of aquaculture water of the Pearl River Delta].

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Cai, Xiaolong; Luo, Jianfei; Lin, Weitie; Tian, Guoliang

2012-05-04

In order to study the characteristic of nitrogen transport, the community structure and diversity of related microorganisms in aquaculture water of the Pearl River Delta. We established an artificial aquaculture ecosystem to study the microbial community of 15N-stable isotope probing (15N-SIP) labeled nitrogen transport microorganisms. The 15N-labeled DNA was separated by CsCl-ethidium bromide density gradient centrifugation, and was used to construct 16S rRNA gene clone libraries of bacteria and archaea. Phylogenetic analysis shows that 19 Operational Taxonomic Units (OTUs) from bacterial library were clustered in Proteobacteria and Planctomycetes. Proteobacteria (99.2%) was the dominant group, mainly consisted of Comamonas (15.7%), Nitrosomonas (12.4%), Enterobacteriaceae (11.5%) and Nitrobacter (11.5%). From archaeal library 9 OTUs were divided into 3 phyla: Thaumarchaeota, Crenarchaeota and Euryarchaeota. We successfully elucidated the microbial community of nitrogen transport microorganisms in aquaculture water of Pearl River Delta by using 15N-SIP. The data of the community will provide essential information for isolating nitrogen degrading microorganism, and provide scientific basis for creating a healthy aquaculture environment.

Analysis of polycyclic aromatic hydrocarbons in tree-rings of Masson pine (Pinus massoniana L.) from two industrial sites in the Pearl River Delta, south China.

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Kuang, Yuan-wen; Zhou, Guo-yi; Wen, Da-zhi; Li, Jiong; Sun, Fang-fang

2011-09-01

Concentrations of polycyclic aromatic hydrocarbons (PAHs) were examined and potential sources of PAHs were identified from the dated tree-rings of Masson pine (Pinus massoniana L.) near two industrial sites (Danshuikeng, DSK and Xiqiaoshan, XQS) in the Pearl River Delta of south China. Total concentrations of PAHs (∑PAHs) were revealed with similar patterns of temporal trends in the tree-rings at both sites, suggesting tree-rings recorded the historical variation in atmospheric PAHs. The differences of individual PAHs and of ∑PAHs detected in the tree-rings between the two sites reflected the historical differences of airborne PAHs. Regional changes in industrial activities might contribute to the site-specific and period-specific patterns of the tree-ring PAHs. The diagnostic PAH ratios of Ant/(Ant + PA), FL/(FL + Pyr), and BaA/(BaA + Chr)) revealed that PAHs in the tree-rings at both sites mainly stemmed from the combustion process (pyrogenic sources). Principal component analysis further confirmed that wood burning, coal combustion, diesel, and gasoline-powered vehicular emissions were the dominant contributors of PAHs sources at DSK, while diesel combustion, gasoline and natural gas combustion, and incomplete coal combustion were responsible for the main origins of PAHs at XQS. Tree-ring analysis of PAHs was indicative of PAHs from a mixture of sources of combustion, thus minimizing the bias of short-term active air sampling.

Changes to subaqueous delta bathymetry following a high river flow event, Wax Lake Delta, LA, USA

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Whaling, A. R.; Shaw, J.

2017-12-01

Sediment transport capacity is increased during high river flow (flood) events which are characterized by discharges that exceed the 15 year median daily statistic. The Wax Lake Delta (WLD) in coastal Louisiana has experienced 19 of these high flow events in the past 20 years, yet the depositional patterns of single floods are rarely measured in a field-scale deltaic setting. We characterize flood deposition and erosion patterns on the subaqueous portion of the WLD by differencing two Digital Elevation Models (DEMs) constructed from bathymetric surveys before and after the third largest flood in the WLD's recorded history. The total suspended sediment discharge for the 496 day inter-survey period was 2.14x107 cubic meters measured 21 km upstream of the delta apex. The difference map showed 1.06x107 cubic meters of sediment was deposited and 8.2x106 cubic meters was eroded, yielding 2.40x106 cubic meters of net deposition in the survey area ( 79.7 km2 ). Therefore the average deposition rate was 0.061 mm/day. Channel planform remained relatively unchanged for five out of six distributary passes however Gadwall Pass experienced a maximum channel displacement of 166 m ( 1 channel width) measured from the thalweg centerline. Channel tip extension was negligible. In addition, channel displacement was not concentrated at any portion along the channel centerline. Maximum erosion occurred within channel margins and increased upstream whereas maximum deposition occurred immediately outside the channel margins. Sediment eroded from the survey area was either subsequently re-deposited or transported out of the system. Our results show that up to 77.4% of deposition in the survey area originated from sediment eroded during the flood. Surprisingly, only 11.2% of the total suspended sediment discharge was retained in the subaqueous portion of the delta after the flood. We conclude that a high flow event does not produce channel progradation. Rather, high flow causes delta

Channel Evolution Following Avulsion: an Example from the Yellow River Delta

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Zheng, S.

2017-12-01

Long-term field observation of morphological adjustments of rivers following avulsions is lacked when studying the evolution of avulsive channel on deltas. Avulsion at the Yellow River Delta (YRD) is frequent with average lifespan of channels of only about a decade. The Qing-shui-gou channel, the recent lobe on the YRD, provides a rare opportunity for investigating channel evolution following artificial avulsion. The reasons for its longer lifespan also needs investigation of the channel evolution. In this study, we comprehensively analyzed the geomorphic adjustment of the channel based on filed survey data during 1976-2014. The evolution of the channel was impacted by anthropogenic activities, including artificial avulsion at the downstream channel reaches in 1996, alteration of runoff and sediment load through Water and Sediment Regulation Scheme (WSRS), construction of levees and dikes. Analysis on channel geometry showed that avulsions in 1976 and in 1996 both caused short-term (1 2 years) erosion at the upstream channel reaches. Following the avulsion in 1976, massive aggradation occurred at the channel reaches at the downstream of the avulsion point. A single-thread channel gradually formed, widened and enlarged as channel bed under-cut on the deposition material. As delta extended seaward and the longitudinal slope decreased with time, aggradation occurred and an alluvial ridge formed. The ratio of lateral slope to the longitudinal slope (i.e. gradient advantage) and the relative super-elevation of the channel were calculated to estimate the possibility of avulsion at the channel in the late 1990. Results showed that the slope ratio was greater than 20 locally and super-elevation near its critical value for avulsion. The fact, that natural avulsion did not occurred despite of high values of gradient advantage and super elevation, may indicate that they are not sufficient conditions for avulsion at highly human-controlled rivers, where channel boundaries are

Source apportionment of ambient volatile organic compounds in the Pearl River Delta, China: Part II

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Liu, Ying; Shao, Min; Lu, Sihua; Chang, Chih-Chung; Wang, Jia-Lin; Fu, Linlin

The chemical mass balance receptor model was applied to the source apportionment of 58 hydrocarbons measured at seven sites in a field campaign that examined regional air quality in the Pearl River Delta (PRD) region in the fall of 2004. A total of 12 volatile organic compound (VOC) emission sources were considered, including gasoline- and diesel-powered vehicle exhausts, headspace vapors of gasoline and diesel fuel, vehicle evaporative emissions, liquid petroleum gas (LPG) leakage, paint vapors, asphalt emissions from paved roads, biomass combustion, coal combustion, the chemical industry, and petroleum refineries. Vehicle exhaust was the largest source of VOCs, contributing to >50% of ambient VOCs at the three urban sites (Guangzhou, Foshan, and Zhongshan). LPG leakage played an important role, representing 8-16% of emissions at most sites in the PRD. Solvent usage was the biggest emitter of VOCs at Dongguan, an industrial site, contributing 33% of ambient VOCs. Similarly, at Xinken, a non-urban site, the evaporation of solvents and coatings was the largest emission source, accounting for 31% of emissions, probably because it was downwind of Dongguan. Local biomass combustion was a noticeable source of VOCs at Xinken; although its contribution was estimated at 14.3%, biomass combustion was the third largest VOC source at this site.

Emergy Synthesis and Regional Sustainability Assessment: Case Study of Pan-Pearl River Delta in China

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Guomin Li

2014-08-01

Full Text Available In this paper, emergy analysis is used in association with the ternary diagrams and geographic information system (GIS tools to improve the evaluation of sustainability for the Pan-Pearl River Delta (PPRD region. Emergy accounting of PPRD is estimated, and various emergy-based indicators are reported. Ternary diagrams are drawn to provide a graphical representation of the emergy accounting data. Finally, the GIS tools are employed to assist in the emergy-based spatial analysis, and emergy density based on flat land area is mapped to reflect the intensity of emergy use in human activity areas. Results show the following: (1 the current development path of the PPRD region, with the value of emergy sustainability index (ESI = 0.227 significantly lower than one, is unsustainable in the long run; (2 Guangdong has the lowest ESI value (0.071, and the ESI values of Fujian, Guangxi, Hunan and Jiangxi are lower than 0.5, indicating that the economy in these provinces overly relies on non-renewable and imported resources; (3 Guizhou has a high emergy yield rate and is thus the main energy supplier in PPRD; and (4 among the nine provinces in PPRD, only Hainan has an ESI value (2.145 higher than one.

Source apportionment of atmospheric mercury pollution in China using the GEOS-Chem model

International Nuclear Information System (INIS)

Wang, Long; Wang, Shuxiao; Zhang, Lei; Wang, Yuxuan; Zhang, Yanxu; Nielsen, Chris; McElroy, Michael B.; Hao, Jiming

2014-01-01

China is the largest atmospheric mercury (Hg) emitter in the world. Its Hg emissions and environmental impacts need to be evaluated. In this study, China's Hg emission inventory is updated to 2007 and applied in the GEOS-Chem model to simulate the Hg concentrations and depositions in China. Results indicate that simulations agree well with observed background Hg concentrations. The anthropogenic sources contributed 35–50% of THg concentration and 50–70% of total deposition in polluted regions. Sensitivity analysis was performed to assess the impacts of mercury emissions from power plants, non-ferrous metal smelters and cement plants. It is found that power plants are the most important emission sources in the North China, the Yangtze River Delta (YRD) and the Pearl River Delta (PRD) while the contribution of non-ferrous metal smelters is most significant in the Southwest China. The impacts of cement plants are significant in the YRD, PRD and Central China. - Highlights: • China's anthropogenic mercury emission was 643.1 t in 2007. • GEOS-Chem model well reproduces the background Hg concentrations. • Anthropogenic emissions contribute 35–50% of Hg concentrations in polluted regions. • The priorities for mercury control in polluted regions are identified. - Anthropogenic Hg emissions are updated and their impacts on atmospheric mercury concentrations and depositions are quantified for China

Impact of emission control on regional air quality in the Pearl Delta River region, southern China

Science.gov (United States)

Wang, N.; Xuejiao, D.

2017-12-01

The Pearl River Delta (PRD) in China has been suffering from air quality issues and the government has implemented a series of strategies in controlling emissions. In an attempt to provide scientific support for improving air quality, the paper investigates the concerning past-to-present air quality data and assesses air quality resulting from emission control. Statistical data revealed that energy consumption doubled from 2004 to 20014 and vehicle usage increased significantly from 2006 to 2014. Due to the effect of control efforts, primary emission of SO2, NOx and PM2.5 decreased resulting in ambient concentrations of SO2, NO2 and PM10 decreased by 66%, 20% and 24%, respectively. However, O3 increased 19% because of the increase of VOC emission. A chemical transport model, the Community Multi-scale Air Quality, was employed to evaluate the responses of nitrate, ammonium, SOA, PM2.5 and O3 to changes in NOx, VOC and NH3 emissions. Three scenarios, a baseline scenario, a CAP scenario (control strength followed as past tendency), and a REF scenario (strict control referred to latest policy and plans), were conducted to investigate the responses and mechanisms. NOx controlling scenarios showed that NOx, nitrate and PM2.5 reduced by 1.8%, 0.7% and 0.2% under CAP and reduced by 7.2%, 1.8% and 0.3% under REF, respectively. The results indicated that reducing NOx emission caused the increase of atmospheric oxidizability, which might result in a compensation of PM2.5 due to the increase of nitrate or sulfate. NH3 controlling scenarios showed that nitrate was sensitive to NH3 emission in PRD, with nitrate decreased by 0 - 10.6% and 0 - 48% under CAP and REF, respectively. Since controlling NH3 emissions not only reduced ammonium but also significantly reduced nitrate, the implement of NH3 controlling strategy was highly suggested. The VOC scenarios revealed that though SOA was not the major component of PM2.5, controlling VOC emission might take effect in southwestern PRD

Assessment of Environmental Flows for the Rivers of Western Ganges Delta with Special Reference to Indian Sundarban

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Bhadra, T.; Hazra, S.; Ghosh, S.; Barman, B. C.

2016-12-01

The Indian Sundarban, situated on the western tide-dominated part of the Ganges delta was formed by the sedimentation of the Ganges and its tributaries. Freshwater is a scarce resource in the Sundarban though it is traversed by rivers. Most of the rivers of Western Ganges Delta, which used to nourish the Sundarban, have become defunct with the passage of time. To ensure sustainable flow and to enhance the flow-dependent ecosystem services in this region, assessment of environmental flows within the system is required. A pilot assessment of environment flows, supported by IUCN has been carried out in some specific river reaches of Western Ganges Delta under the present study. The holistic Building Block Methodology (BBM) has been modified and used for the assessment of environmental flows. In the modified BBM, three distinctive blocks namely Hydro-Morphology, Ecology and Socio-Economy have been selected and indicators like Ganges Dolphin (Platanista gangetica), Sundari tree (Heritiera fomes) and Hilsa fish (Tenualosa ilisha) etc. have been determined to assess the environmental flows. As the discharge data of the selected rivers are restricted in the public domain, the SWAT model has been run to generate the discharge data of the classified rivers. The Hydraulic model, HEC-RAS has been calibrated in the selected River reaches to assess the habitat availability and its changes for indicator species under different flow condition. The study reveals that River Bhagirathi-Hugli requires 150-427 cumec additional water in monsoon and 850-1127 cumec additional water in post-monsoon months for Hilsa migration, whereas 327-486 cumec additional water in pre-monsoon and dry season and 227-386 cumec additional water in post-monsoon months are required for Dolphin movement. Flow requirement of river Ichhamati has also been estimated under the present study. The total required flow for the Sundarban ecosystem to reduce the salinity level from 30ppt to 14ppt during the dry and pre

Losing ground in mega-deltas: basin-scale response to existential threats to the Mekong Delta

Science.gov (United States)

Arias, M. E.; Kondolf, G. M.; Schmitt, R. J. P.; Carling, P. A.; Darby, S. E.; Bizzi, S.; Castelletti, A.; Cochrane, T. A.; Gibson, S.; Kummu, M.; Oeurng, C.; Rubin, Z.; Wild, T. B.

2017-12-01

The Mekong Delta is, in terms of the number of livelihoods it supports, its economic importance, and in its vulnerability to climate change and sinking lands, one of the world's critically threatened mega-deltas. Livelihoods depend on the mere existence of the delta, but also on ecosystem services provided by the delta's drainage basin spanning 795,000 km2 in six abutting countries. These ecosystem services include delivery of sand required to build delta land in the face of rising sea-levels and sediment bound nutrients, provision of spawning habitat for fish that are ultimately harvested in the delta, and hydrologic regulation driving the delta's unique flood-pulse regime. However, while the delta is mainly located in Vietnam, the basin of the Mekong River is shared among China, Myanmar, Laos, Thailand, Cambodia, and Vietnam. In the context of the region's dynamic growth, individual countries are pushing their own development agendas, which include extensive dam building, in-channel sand mining, construction of dykes and canals, and groundwater pumping, all of which contribute to subsidence and erosion of the Delta. Our synthesis of recent research indicates that most of the Mekong's delta land will likely fall below sea-level by 2100 as result of these drivers, exacerbating the impacts of global climatic changes. In this context, local infrastructural projects and changes in land- and water-management may temporarily mitigate some negative effects, but do not address the existential threat to the delta as a whole. To prevent, or at least substantially postpone, the drowning of the Mekong Delta requires identification of the key drivers and immediate concerted management actions on the basin-scale to change the trajectory of subsidence and sediment deficit. A specific challenge is to find the institutional arrangements in this transnational context that could support the needed management changes and equitably distribute costs and impacts. The Mekong Delta is

Detection of formaldehyde emissions from an industrial zone in the Yangtze River Delta region of China using a proton transfer reaction ion-drift chemical ionization mass spectrometer

Science.gov (United States)

Ma, Yan; Diao, Yiwei; Zhang, Bingjie; Wang, Weiwei; Ren, Xinrong; Yang, Dongsen; Wang, Ming; Shi, Xiaowen; Zheng, Jun

2016-12-01

A proton transfer reaction ion-drift chemical ionization mass spectrometer (PTR-ID-CIMS) equipped with a hydronium (H3+O) ion source was developed and deployed near an industrial zone in the Yangtze River Delta (YRD) region of China in spring 2015 to investigate industry-related emissions of volatile organic compounds (VOCs). Air pollutants including formaldehyde (HCHO), aromatics, and other trace gases (O3 and CO) were simultaneously measured. Humidity effects on the sensitivity of the PTR-ID-CIMS for HCHO detection were investigated and quantified. The performances of the PTR-ID-CIMS were also validated by intercomparing with offline HCHO measurement technique using 2,4-dinitrophenylhydrazone (DNPH) cartridges and the results showed fairly good agreement (slope = 0.81, R2 = 0.80). The PTR-ID-CIMS detection limit of HCHO (10 s, three-duty-cycle averages) was determined to be 0.9-2.4 (RH = 1-81.5 %) parts per billion by volume (ppbv) based on 3 times the standard deviations of the background signals. During the field study, observed HCHO concentrations ranged between 1.8 and 12.8 ppbv with a campaign average of 4.1 ± 1.6 ppbv, which was comparable with previous HCHO observations in other similar locations of China. However, HCHO diurnal profiles showed few features of secondary formation. In addition, time series of both HCHO and aromatic VOCs indicated strong influence from local emissions. Using a multiple linear regression fit model, on average the observed HCHO can be attributed to secondary formation (13.8 %), background level (27.0 %), and industry-related emissions, i.e., combustion sources (43.2 %) and chemical productions (16.0 %). Moreover, within the plumes the industry-related emissions can account for up to 69.2 % of the observed HCHO. This work has provided direct evidence of strong primary emissions of HCHO from industry-related activities. These primary HCHO sources can potentially have a strong impact on local and regional air pollution formation

To what extent can China’s near-term air pollution control policy protect air quality and human health? A case study of the Pearl River Delta region

International Nuclear Information System (INIS)

Jiang, Xujia; Hong, Chaopeng; Zheng, Yixuan; Zheng, Bo; Guan, Dabo; Zhang, Qiang; Gouldson, Andy; He, Kebin

2015-01-01

Following a series of extreme air pollution events, the Chinese government released the Air Pollution Prevention and Control Action Plan in 2013 (China’s State Council 2013). The Action Plan sets clear goals for key regions (i.e. cities above the prefecture level, Beijing-Tianjin-Hebei Province, the Yangtze River Delta and the Pearl River Delta) and establishes near-term control efforts for the next five years. However, the extent to which the Action Plan can direct local governments’ activities on air pollution control remains unknown. Here we seek to evaluate the air quality improvement and associated health benefits achievable under the Action Plan in the Pearl River Delta (PRD) area from 2012 to 2017. Measure-by-measure quantification results show that the Action Plan would promise effective emissions reductions of 34% of SO 2 , 28% of NO x , 26% of PM 2.5 (particulate matter less than 2.5 μm in diameter), and 10% of VOCs (volatile organic compounds). These emissions abatements would lower the PM 2.5 concentration by 17%, surpassing the 15% target established in the Action Plan, thereby avoiding more than 2900 deaths and 4300 hospital admissions annually. We expect the implementation of the Action Plan in the PRD would be productive; the anticipated impacts, however, fall short of the goal of protecting the health of local residents, as there are still more than 33 million people living in places where the annual mean ambient PM 2.5 concentrations are greater than 35 μg m −3 , the interim target-3 of the World Health Organization (WHO). We therefore propose the next steps for air pollution control that are important not only for the PRD but also for all other regions of China as they develop and implement effective air pollution control policies. (letter)

To what extent can China’s near-term air pollution control policy protect air quality and human health? A case study of the Pearl River Delta region

Science.gov (United States)

Jiang, Xujia; Hong, Chaopeng; Zheng, Yixuan; Zheng, Bo; Guan, Dabo; Gouldson, Andy; Zhang, Qiang; He, Kebin

2015-10-01

Following a series of extreme air pollution events, the Chinese government released the Air Pollution Prevention and Control Action Plan in 2013 (China’s State Council 2013). The Action Plan sets clear goals for key regions (i.e. cities above the prefecture level, Beijing-Tianjin-Hebei Province, the Yangtze River Delta and the Pearl River Delta) and establishes near-term control efforts for the next five years. However, the extent to which the Action Plan can direct local governments’ activities on air pollution control remains unknown. Here we seek to evaluate the air quality improvement and associated health benefits achievable under the Action Plan in the Pearl River Delta (PRD) area from 2012 to 2017. Measure-by-measure quantification results show that the Action Plan would promise effective emissions reductions of 34% of SO2, 28% of NOx, 26% of PM2.5 (particulate matter less than 2.5 μm in diameter), and 10% of VOCs (volatile organic compounds). These emissions abatements would lower the PM2.5 concentration by 17%, surpassing the 15% target established in the Action Plan, thereby avoiding more than 2900 deaths and 4300 hospital admissions annually. We expect the implementation of the Action Plan in the PRD would be productive; the anticipated impacts, however, fall short of the goal of protecting the health of local residents, as there are still more than 33 million people living in places where the annual mean ambient PM2.5 concentrations are greater than 35 μg m-3, the interim target-3 of the World Health Organization (WHO). We therefore propose the next steps for air pollution control that are important not only for the PRD but also for all other regions of China as they develop and implement effective air pollution control policies.

River delta shoreline reworking and erosion in the Mediterranean and Black Seas: the potential roles of fluvial sediment starvation and other factors

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Manon Besset

2017-09-01

Full Text Available The Mediterranean basin (including the Black Sea is characterized by a plethora of deltas that have developed in a wave-influenced setting. Many of these deltas are sourced in sediments by river catchments that have been variably dammed. The vulnerability status of a selection of ten deltas subject to different levels of reduction in fluvial sediment supply following damming was analysed by quantifying changes in delta protrusion area and protrusion angle over the last 30 years. The rationale for choosing these two metrics, which do not require tricky calculations of longshore bedload transport volumes and river ‘influence’, is that as sediment supply wanes, increasing relative efficiency of waves leads to longshore redistribution of reworked sediments and progressive ‘flattening’ of the delta protrusion. The results show that eight of the ten deltas (Nile, Rhône, Ebro, Ceyhan, Arno, Ombrone, Moulouya, Medjerda are in erosion, whereas two (Danube, Po show stability, but the statistical relationship between change in delta protrusion area and sediment flux reduction is poor, thus suggesting that the role of dams in causing delta shoreline erosion may have been over-estimated. But this poor relationship could also be due to a long temporal lag between dam construction and bedload removal and transport to the coast downstream of dams, and, where the delta protrusion is being eroded, to bedload trapping by shoreline engineering structures and by elongating delta-flank spits. Other potential influential factors in shoreline change include subsidence, sea-level rise, storminess, exceptional river floods, and managed sediment releases downstream of dams. A longer observation period and high-resolution sediment-budget studies will be necessary to determine more definitively to which extent continued trapping of sediment behind dams will impact overall delta stability in the Mediterranean and Black Seas. Mitigation of delta erosion is likely to

Channel-Island Connectivity Affects Water Exposure Time Distributions in a Coastal River Delta

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Hiatt, Matthew; Castañeda-Moya, Edward; Twilley, Robert; Hodges, Ben R.; Passalacqua, Paola

2018-03-01

The exposure time is a water transport time scale defined as the cumulative amount of time a water parcel spends in the domain of interest regardless of the number of excursions from the domain. Transport time scales are often used to characterize the nutrient removal potential of aquatic systems, but exposure time distribution estimates are scarce for deltaic systems. Here we analyze the controls on exposure time distributions using a hydrodynamic model in two domains: the Wax Lake delta in Louisiana, USA, and an idealized channel-island complex. In particular, we study the effects of river discharge, vegetation, network geometry, and tides and use a simple model for the fractional removal of nitrate. In both domains, we find that channel-island hydrological connectivity significantly affects exposure time distributions and nitrate removal. The relative contributions of the island and channel portions of the delta to the overall exposure time distribution are controlled by island vegetation roughness and network geometry. Tides have a limited effect on the system's exposure time distribution but can introduce significant spatial variability in local exposure times. The median exposure time for the WLD model is 10 h under the conditions tested and water transport within the islands contributes to 37-50% of the network-scale exposure time distribution and 52-73% of the modeled nitrate removal, indicating that islands may account for the majority of nitrate removal in river deltas.

Mapping the change of Phragmites australis live biomass in the lower Mississippi River Delta marshes

Science.gov (United States)

Ramsey, Elijah W.; Rangoonwala, Amina

2017-07-28

Multiyear remote sensing mapping of the normalized difference vegetation index (NDVI) was carried out as an indicator of live biomass composition of the Phragmites australis (hereafter Phragmites) marsh in the lower Mississippi River Delta (hereafter delta) from 2014 to 2017. Maps of NDVI change showed that the Phragmites condition was fairly stable between May 2014 and July 2015. From July 2015 to April 2016 NDVI change indicated Phragmites suffered a widespread decline in the live biomass proportion.  Between April and September 2016, most marsh remained unchanged from the earlier period or showed improvement; although there were pockets of continued decline scattered throughout the lower delta. From September 2016 to May 2017 a pronounced and widely exhibited decline in the condition of Phragmites marsh again occurred throughout the lower delta. This final NDVI change mapping supported field observations of Phragmites decline during the same period.

Simulation of the Impacts of Urbanization on Winter Meteorological Fields over the Pearl River Delta Region

Directory of Open Access Journals (Sweden)

Naixing Luo

2017-01-01

Full Text Available The influences of urbanization on weather in Guangdong Province, China, were studied using the Weather Research and Forecasting model from 31 December 2009 through 3 January 2010. Model outputs were compared with extensive monitoring of meteorological data to examine the simulation ability. Model results between tests (with and without land-use change show that the urbanization had major effects on meteorological fields across nearly the entire Pearl River Delta region and particularly in urban areas. Studied fields (wind speed, temperature, precipitation, and sensible and latent heat fluxes were affected by the urbanization of the PRD region. The major influences occurred in urban areas, where wind speeds decreased greatly, while the daytime surface upward sensible heat flux clearly increased. Unlike the sensible heat flux, the latent heat flux had a nonmonotonic increase or decrease. As a consequence of the two heat fluxes, 2-m temperature varied with location and time. Change of precipitation was complex. The main rain band became more concentrated, while precipitation decreased upwind of the urban area and increased downwind.

Flood Damage Assessment in Pearl River Delta Rural Area Application in Huashan Town, Huadu District,Guanghzou during the 2017 5.7 Heavy Rain Storm

Science.gov (United States)

Wang, X.

2017-12-01

The Pearl River Delta (PRD) in China, the summer rain storm occurs frequently, the flood damage is very serious. Damage assessment is the basis of scientific decision-making in disaster mitigation. All approaches of flood damage analysis contain uncertainties due to the inaccuracies and generalisations used, the lack of data aggravates this problem, making methods very rough. This study presents a detailed flood damage assessment framework in Pearl River Delta rural area, using 2017 "5.7" heavy rain storm event to simulate the process and estimate the flood loss in resident building and property, agriculture production. The framework integrates four modules,1) utilize the remote sensing and statistical yearbook and so on to construct the disaster bearing bodies GIS database; 2) using hydraulics model to simulate the flood extent and depth spatial distribution;3)through field investigation to obtain the flood loss data for all kinds of hazard-affected body, using statistical analysis method to get the damage curves;4)Integrate flood scenarios, disaster bearing bodies GIS database and damage curves to calculate the flood loss estimation value. Using this methodology, in the 2017 "5.7" heavy rain storm event, Huashan Town flood damage loss is underestimate compared with the government report, because of not considering the damage of water conservancy facilities. But the disaster loss value on the spatial distribution is consistent with actual situation. In terms of aggregated values in the whole town, the model is capable of obtaining figures that are within the same order of magnitude. This study produce a flood damage assessment framework taking into account the regional characteristics of PRD rural area, provide a template for future practice. This study only considers the current impacts, the framework should be improved by taking into account socio-economic and climatic changes, as well as implementing adaptation measures to be applied to assess the potential

Characteristics of carbonaceous aerosol in PM 2.5: Pearl Delta River Region, China

Science.gov (United States)

Huang, H.; Ho, K. F.; Lee, S. C.; Tsang, P. K.; Ho, Steven Sai Hang; Zou, C. W.; Zou, S. C.; Cao, J. J.; Xu, H. M.

2012-02-01

Simultaneous measurements of atmospheric organic carbon (OC), elemental carbon (EC) and water-soluble organic carbon (WSOC) were made at four sampling sites, namely Guangzhou (GZ), Zhaoqing (ZQ), PolyU Campus (PU) and Hok Tsui (HT), in the Pearl River Delta (PRD) region between 14 August 2006 and 28 August 2007. The highest concentrations of total carbon (TC) were found at the medium-scale roadside site (PU) and the lowest were found at the regional-scale site (HT). Among the four sampling sites, the average WSOC at ZQ showed the highest concentrations, while the lowest were seen at HT. OC and EC concentrations revealed spring/summer minima and autumn/winter maxima at all sites except PU, which had a consistently high EC concentration all over the year. The highest WSOC/OC ratio was found at ZQ with an average of 0.41, suggesting that the OC was more oxidized in the atmosphere of the semi-rural site. The lowest WSOC/OC was found at the roadside site of PU. Moreover, the WSOC/OC ratio increased in autumn, when the photochemical reactions are the most active in the PRD region. This can be attributed to aging and atmospheric processing of the organic compounds during their transportation, or to the formation of secondary organic aerosol (SOA). Average annual secondary organic carbon (SOC) concentrations in PM2.5 were estimated to be 2.2 and 3.5 μg m- 3 for GZ and ZQ, comprising 33.5% and 42.8% of the corresponding OC concentrations, respectively. The results indicate that SOC is significant in the PRD region, and its formation mostly occurs within the region.

Numerical model to quantify biogenic volatile organic compound emissions: The Pearl River Delta region as a case study.

Science.gov (United States)

Wang, Xuemei; Situ, Shuping; Chen, Weihua; Zheng, Junyu; Guenther, Alex; Fan, Qi; Chang, Ming

2016-08-01

This article compiles the actual knowledge of the biogenic volatile organic compound (BVOC) emissions estimated using model methods in the Pearl River Delta (PRD) region, one of the most developed regions in China. The developed history of BVOC emission models is presented briefly and three typical emission models are introduced and compared. The results from local studies related to BVOC emissions have been summarized. Based on this analysis, it is recommended that local researchers conduct BVOC emission studies systematically, from the assessment of model inputs, to compiling regional emission inventories to quantifying the uncertainties and evaluating the model results. Beyond that, more basic researches should be conducted in the future to close the gaps in knowledge on BVOC emission mechanisms, to develop the emission models and to refine the inventory results. This paper can provide a perspective on these aspects in the broad field of research associated with BVOC emissions in the PRD region. Copyright © 2016. Published by Elsevier B.V.

Monitoring Population Evolution in the Pearl River Delta from 2000 TO 2010

Science.gov (United States)

Yu, S.; Liu, F.; Zhang, Z.

2018-04-01

On behalf of more populous and developed regions in China, urban agglomerations have become important carries loading active economic activities and generous social benefits, and experienced sharper population increase, which results in great threat on local eco-environment construction. Therefore, exact and detailed population monitoring and analyzing, especially on the long sequence and multi frequency, is of great significance. The nighttime light time-series (NLT) products has been proven to be one of the most useful remotely sensed imagery to acquire persons at 1 km × 1 km scales. However, the existed problems, such as light saturation and blooming, greatly limit the accuracy of estimated results. Furthermore, it's difficult to spatialize population at km2 level due to the lack of basic data in non-census years. In order to solve all problems mentioned above, the populous Pearl River Delta was selected as the study area. A new residential extent extraction index (REEI) was proposed to solve light saturation and blooming problems. Population spatialization methods in census and non-census years were applied to acquire detailed population distribution from 2000 to 2010. Results showed the feasibility of the proposed methods in this work. During the decade, population was denser in the central PRD and sparser in the eastern, western and northern PRD. The speed of population increase was various in nine cities, but faster in 2000-2005 than 2005-2010.

Performance comparison among the major healthcare financing systems in six cities of the Pearl River Delta region, mainland China.

Directory of Open Access Journals (Sweden)

Martin C S Wong

Full Text Available BACKGROUND: The healthcare system of mainland China is undergoing drastic reform and the optimal models for healthcare financing for provision of primary care will need to be identified. This study compared the performance indicators of the community health centres (CHCs under different healthcare financing systems in the six cities of the Pearl River Delta region. METHODS: Approximately 300 hypertensive patients were randomly recruited from the computerized chronic disease management records provided by one CHC in each of the six cities in 2011 using a multi-stage cluster random sampling method. The major outcome measures included the treatment rate of hypertension, defined as prescription of ≥ one antihypertensive agent; and the control rate of hypertension, defined as systolic blood pressure levels <140 mmHg and diastolic blood pressure levels <90 mmHg in patients without diabetes mellitus, or <130/80 mmHg among patients with concomitant diabetes. Binary logistic regression analyses were conducted with these two measures as outcome variables, respectively, controlling for patients' socio-demographic variables. The financing system (Hospital- vs. Government- vs. private-funded was the independent variable tested for association with the outcomes. RESULTS: From 1,830 patients with an average age of 65.9 years (SD 12.8, the overall treatment and control rates were 75.4% and 20.2%, respectively. When compared with hospital-funded CHCs, patients seen in the Government-funded (adjusted odds ratio [AOR] 0.462, 95% C.I. 0.325-0.656 and private-funded CHCs (AOR 0.031, 95% C.I. 0.019-0.052 were significantly less likely to be prescribed antihypertensive medication. However, the Government-funded CHC was more likely to have optimal BP control (AOR 1.628, 95% C.I. 1.157-2.291 whilst the privately-funded CHC was less likely to achieve BP control (AOR 0.146, 95% C.I. 0.069-0.310, irrespective of whether antihypertensive drugs were prescribed. CONCLUSIONS

2008 USGS/NPS/NASA Experimental Advanced Airborne Research Lidar (EAARL): Pearl River Delta, LA and MS

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — A bare earth elevation map (also known as a Digital Elevation Model or DEM) of the Pearl River Delta in Louisiana and Mississippi was produced from remotely sensed,...

Pesticides in soil and sediment of a dyke-protected area of the Red River Delta, Vietnam

Science.gov (United States)

Braun, Gianna; Bläsing, Melanie; Kruse, Jens; Amelung, Wulf; Renaud, Fabrice; Sebesvari, Zita

2017-04-01

Coastal regions are densely populated but at the same time represent important agricultural areas for food production of the growing world population. To sustain high agricultural yields, in monocultures such as permanent rice systems, pesticides are used in high quantity and frequency. While earlier studies monitored the fate of pesticides in paddy rice systems, the overall fate of these compounds is altered nowadays due to the construction of dykes, which are needed in many delta regions to protect them from high tides, storm surges and salt water intrusion such as in the Red River Delta. The dyke system regulates the discharge and water exchange inside the diked area including irrigation channels for the paddy rice production. Local authorities observed increasing pollution towards the sea (highest pollution close to the dykes) and hypothesized that the dyke system would prevent water exchange and thus lead to an accumulation of pollutants within the diked area. Hence, the purpose of this study was to investigate the effect of dykes on pesticide pollution patterns in coastal delta regions of the Red River Delta. The study was conducted in the district Giao Thuy of the Red River Delta, Vietnam. This area is surrounded by a sea and river dyke; both have several inlet and outlet gates to control the water level in the irrigation channels. We determined the pesticide pollution pattern in a diked agricultural area, as well as along salinity gradients in and outside the diked areas. Samples were taken from rice fields and sediments from irrigation channels inside the diked area as well from saline aquaculture fields located outside the dyke. Pesticide analysis was conducted by accelerated solvent extraction (ASE), followed up by the clean-up process described by Laabs et al. (2007) and analyses using gas chromatography coupled with a mass selective detector (MSD). Preliminary results suggest that out of the 26 analysed compounds chlorpyrifos, propiconazole and

Characteristics and diurnal variations of NMHCs at urban, suburban, and rural sites in the Pearl River Delta and a remote site in South China

Science.gov (United States)

Tang, J. H.; Chan, L. Y.; Chan, C. Y.; Li, Y. S.; Chang, C. C.; Liu, S. C.; Wu, D.; Li, Y. D.

The Pearl River Delta (PRD) is one of the most industrialized and urbanized regions in China. With rapid growth of the economy, it is suffering from deteriorating air quality. Non-methane hydrocarbons (NMHCs) were investigated at urban and suburban sites in Guangzhou (GZ), a rural site in PRD and a clean remote site in South China, in April 2005. Additional roadside samples in GZ and Qingxi (QX, a small industrial town in PRD), ambient air samples at the rooftop of a printing factory in QX and exhaust samples from liquefied petroleum gas (LPG)—fueled taxis in GZ were collected to help identify the source signatures of NMHCs. A large fraction of propane (47%) was found in exhaust samples from LPG-fueled taxis in GZ and extremely high levels of toluene (2.0-3.1 ppmv) were found at the rooftop of the printing factory in QX. Vehicular and industrial emissions were the main sources of NMHCs. The effect of vehicular emission on the ambient air varied among the three PRD sites. The impact of industrial emissions was widespread and they contributed greatly to the high levels of aromatic hydrocarbons, especially toluene, at the three PRD sites investigated. Leakage from vehicles fueled by LPG contributed mainly to the high levels of propane and n-butane at the urban GZ site. Ethane and ethyne from long-range transport and isoprene from local biogenic emission were the main contributors to the total hydrocarbons at the remote site. Diurnal variations of NMHCs showed that the contribution from vehicular emissions varied with traffic conditions and were more influenced by fresh emissions at the urban site and by aged air at the suburban and rural sites. Isoprene from biogenic emission contributed largely to the ozone formation potential (OFP) at the remote site. Ethene, toluene and m/ p-xylene were the main contributors to the OFP at the three PRD sites.

The effects of mariculture on heavy metal distribution in sediments and cultured fish around the Pearl River Delta region, south China.

Science.gov (United States)

Liang, Peng; Wu, Sheng-Chun; Zhang, Jin; Cao, Yucheng; Yu, Shen; Wong, Ming-Hung

2016-04-01

Thirty-six sediment samples were collected from six mariculture sites and corresponding reference sites (approximately 200-300 m away from each mariculture site) to study the effects of mariculture on heavy metal: copper (Cu), zinc (Zn), chromium (Cr) and lead (Pb) distribution in sediments and cultured fish around the Pearl River Delta region, south China. The mean concentrations of Cu, Zn, Cr and Pb in all mariculture sediment samples were 109, 273, 99 and 33 mg/kg, compared with 63, 209, 56 and 23 mg/kg for reference sediment samples, respectively. The Pollution Load Index of sediment for each site was over 1, implying substantial heavy metal pollution. The results of principal component analysis and hierarchical clustering analysis indicate that marine aquaculture activities have enriched the surface sediments underneath mariculture rafts with Cu, Zn and Pb, possibly due to the accumulation of unconsumed fish feeds, fish excreta and antifouling paints (except Cr). Two kinds of fish feeds, feed pellets and trash fish commonly used in Hong Kong were analyzed. The concentrations of Zn and Cu contained in feed pellets were significantly higher (p trash fish due to addition of these elements as growth promoters during pellet production. However, the Pb content in trash fish (due to contamination) was significantly higher (p < 0.05) than in feed pellets. Three cultured fish species, namely red snapper (Lutjanus campechanus), orange-spotted grouper (Epinephelus coioides) and snubnose pompano (Trachinotus blochii), were collected from each mariculture site for metal analysis. Lead concentrations in 21 fish samples exceeded the Chinese safety guideline (0.5 mg/kg, GB18406.4-2001), indicating that Pb contamination in cultured fish would be a public health concern. Copyright © 2015. Published by Elsevier Ltd.

Column-integrated aerosol optical properties and direct radiative forcing over the urban-industrial megacity Nanjing in the Yangtze River Delta, China.

Science.gov (United States)

Kang, Na; Kumar, K Raghavendra; Yu, Xingna; Yin, Yan

2016-09-01

Aerosol optical properties were measured and analyzed through the ground-based remote sensing Aerosol Robotic Network (AERONET) over an urban-industrial site, Nanjing (32.21° N, 118.72° E, and 62 m above sea level), in the Yangtze River Delta, China, during September 2007-August 2008. The annual averaged values of aerosol optical depth (AOD500) and the Ångström exponent (AE440-870) were measured to be 0.94 ± 0.52 and 1.10 ± 0.21, respectively. The seasonal averaged values of AOD500 (AE440-870) were noticed to be high in summer (autumn) and low in autumn (spring). The characterization of aerosol types showed the dominance of mixed type followed by the biomass burning and urban-industrial type of aerosol at Nanjing. Subsequently, the curvature (a 2) obtained from the second-order polynomial fit and the second derivative of AE (α') were also analyzed to understand the dominant aerosol type. The single scattering albedo at 440 nm (SSA440) varied from 0.88 to 0.93 with relatively lower (higher) values during the summer (spring), suggesting an increase in black carbon and mineral dust (desert dust) aerosols of absorbing (scattering) nature. The averaged monthly and seasonal evolutions of shortwave (0.3-4.0 μm) direct aerosol radiative forcing (DARF) values were computed from the Santa Barbara DISORT Atmospheric Radiative Transfer (SBDART) model both at the top of atmosphere (TOA) and bottom of atmosphere (SUR) during the study period. Further, the aerosol forcing efficiency (AFE) and the corresponding atmospheric heating rates (AHR) were also estimated from the forcing within the atmosphere (ATM). The derived DARF values, therefore, produced a warming effect within the atmosphere due to strong absorption of solar radiation.

Behavior and reproductive success of Rock Sandpipers breeding on the Yukon-Kuskokwim River Delta, Alaska

NARCIS (Netherlands)

Johnson, Matthew; Conklin, J.R.; Johnson, Branden; McCaffery, Brian J.; Haig, Susan M.; Walters, Jeffrey R.

2009-01-01

We studied Rock Sandpiper (Calidris ptilocnemis) breeding behavior and monitored reproductive success from 1998 to 2005 on the Yukon-Kuskokwim River Delta, Alaska, USA. We banded 24 adults and monitored 45 nests. Annual return rate of adults ranged between 67 and 100%. Six pairs of Rock Sandpipers

River, delta and coastal morphological response accounting for biological dynamics

Science.gov (United States)

Goldsmith, W.; Bernardi, D.; Schippa, L.

2015-03-01

Management and construction can increase resilience in the face of climate change, and benefits can be enhanced through integration of biogenic materials including shells and vegetation. Rivers and coastal landforms are dynamic systems that respond to intentional and unintended manipulation of critical factors, often with unforeseen and/or undesirable resulting effects. River management strategies have impacts that include deltas and coastal areas which are increasingly vulnerable to climate change with reference to sea level rise and storm intensity. Whereas conventional assessment and analysis of rivers and coasts has relied on modelling of hydrology, hydraulics and sediment transport, incorporating additional biological factors can offer more comprehensive, beneficial and realistic alternatives. Suitable modelling tools can provide improved decision support. The question has been whether current models can effectively address biological responses with suitable reliability and efficiency. Since morphodynamic evolution exhibits its effects on a large timescale, the choice of mathematical model is not trivial and depends upon the availability of data, as well as the spatial extent, timelines and computation effort desired. The ultimate goal of the work is to set up a conveniently simplified river morphodynamic model, coupled with a biological dynamics plant population model able to predict the long-term evolution of large alluvial river systems managed through bioengineering. This paper presents the first step of the work related to the application of the model accounting for stationary vegetation condition. Sensitivity analysis has been performed on the main hydraulic, sedimentology, and biological parameters. The model has been applied to significant river training in Europe, Asia and North America, and comparative analysis has been used to validate analytical solutions. Data gaps and further areas for investigation are identified.

Ecosystem Service Value for the Common Reed Wetlands in the Liaohe Delta, Northeast China

DEFF Research Database (Denmark)

Ye, Siyuan; Laws, Edward A.; Costanza, Robert

2016-01-01

The largest reed field in the world, with an area of 1000 km2 in 1953, is located in the Liaohe Delta, which lies in the five-point-in-a-line economic strategic zone of northeastern China. However, the area of reeds has declined dramatically in recent years to accommodate oil field infrastructure...

[Study on the content and carbon isotopic composition of water dissolved inorganic carbon from rivers around Xi'an City].

Science.gov (United States)

Guo, Wei; Li, Xiang-Zhong; Liu, Wei-Guo

2013-04-01

In this study, the content and isotopic compositions of water dissolved inorganic carbon (DIC) from four typical rivers (Chanhe, Bahe, Laohe and Heihe) around Xi'an City were studied to trace the possible sources of DIC. The results of this study showed that the content of DIC in the four rivers varied from 0.34 to 5.66 mmol x L(-1) with an average value of 1.23 mmol x L(-1). In general, the content of DIC increased from the headstream to the river mouth. The delta13C(DIC) of four rivers ranged from -13.3 per thousand to -7.2 per thousand, with an average value of -10.1 per thousand. The delta13C(DIC) values of river water were all negative (average value of -12.6 per thousand) at the headstream of four rivers, but the delta13C(DIC) values of downstream water were more positive (with an average value of -9.4 per thousand). In addition, delta13C(DIC) of river water showed relatively negative values (the average value of delta13C(DIC) was -10.5 per thousand) near the estuary of the rivers. The variation of the DIC content and its carbon isotope suggested that the DIC sources of the rivers varied from the headstream to the river mouth. The negative delta13C(DIC) value indicated that the DIC may originate from the soil CO2 at the headstream of the rivers. On the other hand, the delta13C(DIC) values of river water at the middle and lower reaches of rivers were more positive, and it showed that soil CO2 produced by respiration of the C4 plants (like corn) and soil carbonates with positive delta13C values may be imported into river water. Meanwhile, the input of pollutants with low delta13C(DIC) values may result in a decrease of delta13C(DIC) values in the rivers. The study indicated that the DIC content and carbon isotope may be used to trace the sources of DIC in rivers around Xi'an City. Our study may provide some basic information for tracing the sources of DIC of rivers in the small watershed area in the Loess Plateau of China.

Geochronology of priority pollutants in sedimentation zones of the Volga and Danube delta in comparison with the Rhine delta

International Nuclear Information System (INIS)

Winkels, H.J.; Kroonenberg, S.B.; Lychagin, M.Y.; Marin, G.; Rusakov, G.V.; Kasimov, N.S.

1998-01-01

Six sediment cores were taken in sedimentation zones of the Volga river (located in the southern part of the Russian Federation) and, additionally, 6 sediment cores were taken in several lakes (sedimentation zones) in the central and western part of the Danube delta in Romania. Priority pollutants (8 metals, 7 polychlorinated biphenyls and 10 polycyclic aromatic hydrocarbons) were determined in all samples of all cores. Present-day and historical levels of pollutants since the late 1930s were established through the use of radionuclide time tracers ( 137 Cs, 134 Cs). For the persistent metals and polycyclic aromatic hydrocarbons, trends in the concentration profiles during the last 5 decades are described. Low and hardly changing concentrations of As, Cu, Zn and all studied PAHs were observed during the last five decades in the sediments of the Volga river. Recently deposited sediments show slightly increasing levels for the heavy metals Zn and Cr and As in the Volga delta. For the studied metals and PAHs, maximum concentrations were found around 1987 in the sediments of the Danube delta. Sediments deposited around 1940 and recently deposited sediments in the Danube delta showed lower pollutant levels. If the contents of heavy metals, PAHs and PCBs in the aquatic sediments in the deltas of the rivers Rhine, Danube and Volga are compared, it is clear that the Volga delta is and was the cleanest delta during the last 5 decades. Nowadays the contents of heavy metals (except Cu and Ni), PAHs and PCBs in the aquatic sediments of the river Rhine are still highest compared to the other two rivers. The recent load of heavy metals (except Cd and Zn) in the sediments of the river Danube is the highest compared to the other two rivers. (Copyright (c) 1998 Elsevier Science B.V., Amsterdam. All rights reserved.)

The changing hydro-ecological dynamics of rivers and deltas of the Western Indian Ocean: Anthropogenic and environmental drivers, local adaptation and policy response

Science.gov (United States)

Duvail, Stéphanie; Hamerlynck, Olivier; Paron, Paolo; Hervé, Dominique; Nyingi, Wanja D.; Leone, Michele

2017-10-01

The rivers flowing into the Western Indian Ocean have steep headwater gradients and carry high sediment loads. In combination with strong tides and seasonal rainfall, these rivers create dynamic deltas with biodiversity-rich and productive ecosystems that, through flooding, have sustained indigenous use systems for centuries. However, river catchments are rapidly changing due to deforestation. Hydropower dams also increasingly alter flood characteristics, reduce sediment supply and contribute to coastal erosion. These impacts are compounded by climate change. Altogether, these changes affect the livelihoods of the delta users. Here, based on prior works that we and others have conducted in the region, we analyse the drivers of these hydro-ecological changes. We then provide recommendations for improved dam design and operations to sustain the underlying delta-building processes, the ecosystem values and the needs of the users.

[Integrated assessment of eco-environmental vulnerability in Pearl River Delta based on RS and GIS].

Science.gov (United States)

Xu, Qing-Yong; Huang, Mei; Liu, Hong-Sheng; Yan, Hui-Min

2011-11-01

Based on the remote sensing data and with the help of geographic information system, an integrated assessment was conducted on the eco-environmental vulnerability of Pearl River Delta in 2004-2008. Spatial principal component analysis was used to generate the evaluation indicators, and analytic hierarchy process (AHP) was applied to determine the weights of the evaluation factors. The reasons causing the vulnerability of the eco- environment in Pearl River Delta were discussed. In the study area, its middle part was the most vulnerable region, occupying 34.0% of the total, eastern part was the moderately vulnerable region, accounting for 25.5%, and western part was the lightly and slightly vulnerable areas, accounting for 28.7 and 11.8%, respectively. Totally, the moderately and lightly vulnerable areas occupied 54.2%, indicating that a majority of the Delta was under moderate and light vulnerability. The natural factors affecting the eco-environmental vulnerability of the Delta were altitude, heavy rain days, water and soil erosion rate, flooded infield rate, normalized difference vegetation index (ND VI) and landscape diversity index, whereas the human factors were population density, waste discharge per unit area, exhaust emission per unit area, land use change, chemical fertilization intensity, pesticide application intensity, amount of motor vehicles possessed by ten thousands people, and index of environmental protection investment. The main characteristics of the extremely and heavily vulnerable regions were low altitude, high frequency of flood disaster, large flooded infield, serious vegetation degradation, high pollution level and low environment protection investment index.

Ambient levels and temporal variations of PM2.5 and PM10 at a residential site in the mega-city, Nanjing, in the western Yangtze River Delta, China.

Science.gov (United States)

Shen, Guo F; Yuan, Si Y; Xie, Yu N; Xia, Si J; Li, Li; Yao, Yu K; Qiao, Yue Z; Zhang, Jie; Zhao, Qiu Y; Ding, Ai J; Li, Bin; Wu, Hai S

2014-01-01

The deteriorating air quality in eastern China including the Yangtze River Delta is attracting growing public concern. In this study, we measured the ambient PM10 and fine PM2.5 in the mega-city, Nanjing at four different times. The 24-h average PM2.5 and PM10 mass concentrations were 0.033-0.234 and 0.042-0.328 mg/m(3), respectively. The daily PM10 and PM2.5 concentrations were 2.9 (2.7-3.2, at 95% confidence interval) and 4.2 (3.8-4.6) times the WHO air quality guidelines of 0.025 mg/m(3) for PM2.5 and 0.050 mg/m(3) for PM10, respectively, which indicated serious air pollution in the city. There was no obvious weekend effect. The highest PM10 pollution occurred in the wintertime, with higher PM2.5 loadings in the winter and summer. PM2.5 was correlated significantly with PM10 and the average mass fraction of PM2.5 in PM10 was about 72.5%. This fraction varied during different sampling periods, with the lowest PM2.5 fraction in the spring but minor differences among the other three seasons.

Spatial and temporal trends of reference crop evapotranspiration and its influential variables in Yangtze River Delta, eastern China

Science.gov (United States)

Xu, Yu; Xu, Youpeng; Wang, Yuefeng; Wu, Lei; Li, Guang; Song, Song

2017-11-01

Reference crop evapotranspiration (ETo) is one of the most important links in hydrologic circulation and greatly affects regional agricultural production and water resource management. Its variation has drawn more and more attention in the context of global warming. We used the Penman-Monteith method of the Food and Agriculture Organization, based on meteorological factors such as air temperature, sunshine duration, wind speed, and relative humidity to calculate the ETo over 46 meteorological stations located in the Yangtze River Delta, eastern China, from 1957 to 2014. The spatial distributions and temporal trends in ETo were analyzed based on the modified Mann-Kendall trend test and linear regression method, while ArcGIS software was employed to produce the distribution maps. The multiple stepwise regression method was applied in the analysis of the meteorological variable time series to identify the causes of any observed trends in ETo. The results indicated that annual ETo showed an obvious spatial pattern of higher values in the north than in the south. Annual increasing trends were found at 34 meteorological stations (73.91 % of the total), which were mainly located in the southeast. Among them, 12 (26.09 % of the total) stations showed significant trends. We saw a dominance of increasing trends in the monthly ETo except for January, February, and August. The high value zone of monthly ETo appeared in the northwest from February to June, mid-south area from July to August, and southeast coastal area from September to January. The research period was divided into two stages—stage I (1957-1989) and stage II (1990-2014)—to investigate the long-term temporal ETo variation. In stage I, almost 85 % of the total stations experienced decreasing trends, while more than half of the meteorological stations showed significant increasing trends in annual ETo during stage II except in February and September. Relative humidity, wind speed, and sunshine duration were

Surface-ground water interactions and hydrogeochemical evolution in a fluvio-deltaic setting: The case study of the Pinios River delta

Science.gov (United States)

Matiatos, Ioannis; Paraskevopoulou, Vasiliki; Lazogiannis, Konstantinos; Botsou, Fotini; Dassenakis, Manos; Ghionis, George; Alexopoulos, John D.; Poulos, Serafim E.

2018-06-01

River deltas sustain important ecosystems with rich biodiversity and large biomass, as well as human populations via the availability of water and food sources. Anthropogenic activities, such as urbanization, tourism and agriculture, may pose threats to river deltas. The knowledge of the factors controlling the regional water quality regime in these areas is important for planning sustainable use and management of the water resources. Here, hydrochemical methods and multivariate statistical techniques were combined to investigate the shallow aquifer of the Pinios River (Thessaly) deltaic plain with respect to water quality, hydrogeochemical evolution and interactions between groundwater and surface water bodies. Water quality assessment indicated that most of the river and groundwater samples fully comply with the criteria set by the Drinking Water Directive (98/83/EC). The river is recharged mainly from springs of the Tempi valley and the shallow aquifer, and to a lesser degree from precipitation, throughout the year. The hydrogeochemical characteristics indicated a cation (Ca, Mg, and Na) bicarbonate water type, which evolves to calcium-chloride, sodium-bicarbonate and sodium-chloride water type, in the northern part of the delta. Calcite and dolomite dissolution determined the major ion chemistry, but other processes, such as silicate weathering and cation exchange reactions, also contributed. In the northern part of the plain, the interaction with the deeper aquifer enriched the shallow aquifer with Na and Cl ions. Principal Component Analysis showed that five components (PCs) explain 77% of the total variance of water quality parameters; these are: (1) salinity; (2) water-silicate rocks interaction; (3) hardness due to calcite dissolution, and cation exchange processes; (4) nitrogen pollution; and (5) non-N-related artificial fertilizers. This study demonstrated that the variation of water hydrochemistry in the deltaic plain could be attributed to natural and

Soil properties of mangroves in contrasting geomorphic settings within the Zambezi River Delta, Mozambique

Science.gov (United States)

Christina E. Stringer; Carl C. Trettin; Stan Zarnoch

2016-01-01

Mangroves are well-known for their numerous ecosystem services, including sequestering a significant carbon stock, with soils accounting for the largest pool. The soil carbon pool is dependent on the carbon content and bulk density. Our objective was to assess the spatial variability of mangrove soil physical and chemical properties within the Zambezi River Delta and...

Sedimentology of Fraser River delta peat deposits: a modern analogue for some deltaic coals

Energy Technology Data Exchange (ETDEWEB)

Styan, W B; Bustin, R M

1984-01-01

On the Recent lobe of the Fraser River delta, peat accumulation has actively occurred on the distal lower delta plain, the transition between upper and lower delta plains, and the alluvial plain. Distal lower delta plain peats developed from widespread salt and brackish marshes and were not influenced appreciably by fluvial activity. Lateral development of the marsh facies were controlled by compaction and eustatic sea-level rise. The resulting thin, discontinuous peat network contains numerous silty clay partings and high concentrations of sulphur. Freshwater marsh facies formed but were later in part eroded and altered by transgressing marine waters. Peats overlie a thin, fluvial, fining-upward sequence which in turn overlies a thick, coarsening-upward, prodelta-delta front succession. Lower- upper delta plain peats initially developed from interdistributary brackish marshes and were later fluvially influenced as the delta prograded. Thickest peats occur in areas where distributary channels were abandoned earliest. Sphagnum biofacies replace sedge-grass-dominated communities except along active channel margins, where the sedge-grass facies is intercalated with overbank and splay deposits. Peats are underlain by a relatively thin sequence of fluvial deposits which in turn is underlain by a major coarsening-upward delta front and pro-delta sequence. Alluvial plain peats accumulated in back swamp environments of the flood plain. Earliest sedge-clay and gyttja peats developed over thin fining-upward fluvial cycles or are interlaminated with fine-grained flood deposits. Thickest accumulations occur where peat fills small avulsed flood channels. Overlying sedge-grass and sphagnum biofacies are horizontally stratified and commonly have sharp boundaries with fine-grained flood sediments. At active channel margins, however, sedge-grass peats are intercalated with natural levee deposits consisting of silty clay.

How Rapid Change Affects Deltas in the Arctic Region

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Overeem, I.; Bendixen, M.

2017-12-01

Deltas form where the river drains into the ocean. Consequently, delta depositional processes are impacted by either changes in the respective river drainage basin or by changes in the regional marine environment. In a warming Arctic region rapid change has occurred over the last few decades in both the terrestrial domain as well as in the marine domain. Important terrestrial controls include 1) change in permafrost possibly destabilizing river banks, 2) strong seasonality of river discharge due to a short melting season, 3) high sediment supply if basins are extensively glaciated, 4) lake outbursts and ice jams favoring river flooding. Whereas in the Arctic marine domain sea ice loss promotes wave and storm surge impact, and increased longshore transport. We here ask which of these factors dominate any morphological change in Arctic deltas. First, we analyze hydrological data to assess change in Arctic-wide river discharge characteristics and timing, and sea ice concentration data to map changes in sea ice regime. Based on this observational analysis we set up a number of scenarios of change. We then model hypothetical small-scale delta formation considering change in these primary controls by setting up a numerical delta model, and combining it dynamically with a permafrost model. We find that for typical Greenlandic deltas changes in river forcing due to ice sheet melt dominate the morphological change, which is corroborated by mapping of delta progradation from aerial photos and satellite imagery. Whereas in other areas, along the North Slope and the Canadian Arctic small deltas are more stable or experienced retreat. Our preliminary coupled model allows us to further disentangle the impact of major forcing factors on delta evolution in high-latitude systems.

Ecology of Juvenile Salmonids in Shallow Tidal Freshwater Habitats in the Vicinity of the Sandy River Delta, Lower Columbia River, 2007

Energy Technology Data Exchange (ETDEWEB)

Sobocinski, Kathryn L.; Johnson, Gary E.; Sather, Nichole K.; Storch, Adam; Jones, Tucker A.; Mallette, Christine; Dawley, Earl M.; Skalski, John R.; Teel, David; Moran, Paul

2008-03-18

This document is the first annual report for the study titled “Ecology of Juvenile Salmonids in Shallow Tidal Freshwater Habitats in the Vicinity of the Sandy River Delta in the Lower Columbia River.” Hereafter, we refer to this research as the Tidal Freshwater Monitoring (TFM) Study. The study is part of the research, monitoring, and evaluation effort developed by the Action Agencies (Bonneville Power Administration, U.S. Army Corps of Engineers, U.S. Bureau of Reclamation) in response to obligations arising from the Endangered Species Act as a result of operation of the Federal Columbia River Power System (FCRPS). The project is performed under the auspices of the Northwest Power and Conservation Council’s Columbia Basin Fish and Wildlife Program.

Human induced discharge diversion in a tropical delta and its environmental implications: The Patía River, Colombia

Science.gov (United States)

Restrepo, Juan D.; Kettner, Albert

2012-03-01

SummaryThe Patía River, the number one in terms of sediment yield ˜1500 t km-2 yr-1 draining the western South America, has the most extensive and well developed delta on the Pacific coast, measuring 1700 km2. During the Holocene, nature forced the Patía delta to the south; however, a major water diversion, starting in 1972, diverted the Patía flow to the Sanguianga River, the latter, a small stream draining internal lakes from the Pacific lowlands. This human induced discharge diversion shifted the active delta plain back to the north and changed the northern estuarine system into an active delta plain. Overall, major environmental consequences of this discharge diversion in terms of morphological changes along the delta coast and distributary channels, are evidenced by: (1) coastal retreat along the abandoned delta lobe; 63% of the southern shoreline is retreating at maximum rates of 7 m yr-1, with a corresponding coastal land loss of 106 m yr-1; (2) transgressive barrier islands with exposed peat soils in the surf zone; (3) abandonment of former active distributaries in the southern delta plain with associated closing of inlets and formation of ebb tidal deltas; (4) breaching events on barrier islands; and (5) distributary channel accretion in the northern delta plain by morphological processes such as sedimentation (also in crevasses), overbank flow, increasing width of levees, interdistributary channel fill, and colonization of pioneer mangrove. The Sanguianga Mangrove National Park (SMNP), the largest mangrove reserve in Colombia, measuring 800 km2, lies in this former estuary, where major hydrologic and sedimentation changes are occurring. Observed environmental changes in the SMNP, include (1) seaward advance of the sub-aqueous delta front at the Sanquianga inlet evidenced by an increase in tidal flat area from 5.4 Mm2 in 1986 to 14 Mm2 in 2001; (2) freshening conditions in the Sanguianga distributary channel, a hydrologic change that has shifted the

Modeling multi-source flooding disaster and developing simulation framework in Delta

Science.gov (United States)

Liu, Y.; Cui, X.; Zhang, W.

2016-12-01

Most Delta regions of the world are densely populated and with advanced economies. However, due to impact of the multi-source flooding (upstream flood, rainstorm waterlogging, storm surge flood), the Delta regions is very vulnerable. The academic circles attach great importance to the multi-source flooding disaster in these areas. The Pearl River Delta urban agglomeration in south China is selected as the research area. Based on analysis of natural and environmental characteristics data of the Delta urban agglomeration(remote sensing data, land use data, topographic map, etc.), hydrological monitoring data, research of the uneven distribution and process of regional rainfall, the relationship between the underlying surface and the parameters of runoff, effect of flood storage pattern, we use an automatic or semi-automatic method for dividing spatial units to reflect the runoff characteristics in urban agglomeration, and develop an Multi-model Ensemble System in changing environment, including urban hydrologic model, parallel computational 1D&2D hydrodynamic model, storm surge forecast model and other professional models, the system will have the abilities like real-time setting a variety of boundary conditions, fast and real-time calculation, dynamic presentation of results, powerful statistical analysis function. The model could be optimized and improved by a variety of verification methods. This work was supported by the National Natural Science Foundation of China (41471427); Special Basic Research Key Fund for Central Public Scientific Research Institutes.

Development of a global river-coastal coupling model and its application to flood simulation in Asian mega-delta regions

Science.gov (United States)

Ikeuchi, Hiroaki; Hirabayashi, Yukiko; Yamazaki, Dai; Muis, Sanne; Ward, Philip; Verlaan, Martin; Winsemius, Hessel; Kanae, Shinjiro

2017-04-01

The world's mega-delta regions and estuaries are susceptible to various water-related disasters, such as river flooding and storm surge. Moreover, simultaneous occurrence of them would be more devastating than a situation where they occur in isolation. Therefore, it is important to provide information about compound risks of fluvial and coastal floods at a large scale, both their statistical dependency as well as their combined resulting flooding in delta regions. Here we report on a first attempt to address this issue globally by developing a method to couple a global river model (CaMa-Flood) and a global tide and surge reanalysis (GTSR) dataset. A state-of-the-art global river routing model, CaMa-Flood, was modified to represent varying sea levels due to tides and storm surges as downstream boundary condition, and the GTSR dataset was post-processed to serve as inputs to the CaMa-Flood river routing simulation and a long-term simulation was performed to incorporate the temporal dependency between coastal tide and surge on the one hand, and discharge on the other. The coupled model was validated against observations, showing better simulation results of water levels in deltaic regions than simulation without GTSR. For example in the Ganges Delta, correlation coefficients were increased by 0.06, and root mean square errors were reduced by 0.22 m. Global coupling simulations revealed that storm surges affected river water levels in coastal regions worldwide, especially in low-lying flat areas with increases in water level larger than 0.5 m. By employing enhanced storm surge simulation with tropical storm tracks, we also applied the model to examine impacts of past hurricane and cyclone storm events on river flood inundation.

Optimality and self-organization in river deltas

Science.gov (United States)

Tejedor, A.; Longjas, A.; Edmonds, D. A.; Zaliapin, I. V.; Georgiou, T. T.; Rinaldo, A.; Foufoula-Georgiou, E.

2017-12-01

Deltas are nourished by channel networks, whose connectivity constrains, if not drives, the evolution, functionality and resilience of these systems. Understanding the coevolution of deltaic channels and their flux organization is crucial for guiding maintenance strategies of these highly stressed systems from a range of anthropogenic activities. However, in contrast to tributary channel networks, to date, no theory has been proposed to explain how deltas self-organize to distribute water and sediment to the delta top and the shoreline. Here, we hypothesize the existence of an optimality principle underlying the self-organized partition of fluxes in delta channel networks. Specifically, we hypothesize that deltas distribute water and sediment fluxes on a given delta topology such as to maximize the diversity of flux delivery to the shoreline. By introducing the concept of nonlocal Entropy Rate (nER) and analyzing ten field deltas in diverse environments, we present evidence that supports our hypothesis, suggesting that delta networks achieve dynamically accessible maxima of their nER. Furthermore, by analyzing six simulated deltas using the Delf3D model and following their topologic and flux re-organization before and after major avulsions, we further study the evolution of nER and confirm our hypothesis. We discuss how optimal flux distributions in terms of nER, when interpreted in terms of resilience, are configurations that reflect an increased ability to withstand perturbations.

River, delta and coastal morphological response accounting for biological dynamics

Directory of Open Access Journals (Sweden)

W. Goldsmith

2015-03-01

Full Text Available Management and construction can increase resilience in the face of climate change, and benefits can be enhanced through integration of biogenic materials including shells and vegetation. Rivers and coastal landforms are dynamic systems that respond to intentional and unintended manipulation of critical factors, often with unforeseen and/or undesirable resulting effects. River management strategies have impacts that include deltas and coastal areas which are increasingly vulnerable to climate change with reference to sea level rise and storm intensity. Whereas conventional assessment and analysis of rivers and coasts has relied on modelling of hydrology, hydraulics and sediment transport, incorporating additional biological factors can offer more comprehensive, beneficial and realistic alternatives. Suitable modelling tools can provide improved decision support. The question has been whether current models can effectively address biological responses with suitable reliability and efficiency. Since morphodynamic evolution exhibits its effects on a large timescale, the choice of mathematical model is not trivial and depends upon the availability of data, as well as the spatial extent, timelines and computation effort desired. The ultimate goal of the work is to set up a conveniently simplified river morphodynamic model, coupled with a biological dynamics plant population model able to predict the long-term evolution of large alluvial river systems managed through bioengineering. This paper presents the first step of the work related to the application of the model accounting for stationary vegetation condition. Sensitivity analysis has been performed on the main hydraulic, sedimentology, and biological parameters. The model has been applied to significant river training in Europe, Asia and North America, and comparative analysis has been used to validate analytical solutions. Data gaps and further areas for investigation are identified.

Mining the Urban Sprawl Pattern: A Case Study on Sunan, China.

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Ma, Ronghua; Gu, Chaolin; Pu, Yingxia; Ma, Xiaodong

2008-10-14

China's urbanization is going into a fast development stage. This paper focuses on the recent evolution of an urbanized area - Sunan, the southern part of Jiangsu province in the Yangtze River Delta in China - by means of complementary approaches, especially different fractal and autocorrelation measures. The research shows that Sunan's urban clusters are becoming more and more homogenous and compact and are growing up along the important transportation axes. The enriching discussion of the findings establishes the links between the morphology of urban sprawl and recent socio-economic changes in China.

Aerosol number size distribution and new particle formation at a rural/coastal site in Pearl River Delta (PRD) of China

Science.gov (United States)

Liu, Shang; Hu, Min; Wu, Zhijun; Wehner, Birgit; Wiedensohler, Alfred; Cheng, Yafang

Continuous measurements of aerosol number size distribution in the range of 3 nm-10 μm were performed in Pearl River Delta (PRD), China. These measurements were made during the period of 3 October to 5 November in 2004 at rural/coastal site, Xinken (22°37'N, 113°35'E, 6 m above sea level), in the south suburb of Guangzhou City (22°37'N, 113°35'E, 6 m above sea level), using a Twin Differential Mobility Particle Sizer (TDMPS) combined with an Aerodynamic Particle Sizer (APS). The aerosol particles at Xinken were divided into four groups according to the observation results: nucleation mode particles (3-30 nm), Aitken mode particles (30-130 nm), accumulation mode particles (130-1000 nm) and coarse mode particles (1-10 μm). Concentrations of nucleation mode, Aitken mode and accumulation mode particles were observed in the same order of magnitude (about 10,000 cm -3), among which the concentration of Aitken mode particle was the highest. The Aitken mode particles usually had two peaks: the morning peak may be caused by the land-sea circulation, which is proven to be important for transporting aged aerosols back to the sampling site, while the noon peak was ascribed to the condensational growth of new particles. New particle formation events were found on 7 days of 27 days, the new particle growth rates ranged from 2.2 to 19.8 nm h -1 and the formation rates ranged from 0.5 to 5.2 cm -3 s -1, both of them were in the range of typical observed formation rates (0.01-10 cm -3 s -1) and typical particle growth rates (1-20 nm h -1). The sustained growth of the new particles for several hours under steady northeast wind indicated that the new particle formation events may occur in a large homogeneous air mass.

Full-Coverage High-Resolution Daily PM(sub 2.5) Estimation using MAIAC AOD in the Yangtze River Delta of China

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Xiao, Qingyang; Wang, Yujie; Chang, Howard H.; Meng, Xia; Geng, Guannan; Lyapustin, Alexei Ivanovich; Liu, Yang

2017-01-01

Satellite aerosol optical depth (AOD) has been used to assess population exposure to fine particulate matter (PM (sub 2.5)). The emerging high-resolution satellite aerosol product, Multi-Angle Implementation of Atmospheric Correction(MAIAC), provides a valuable opportunity to characterize local-scale PM(sub 2.5) at 1-km resolution. However, non-random missing AOD due to cloud snow cover or high surface reflectance makes this task challenging. Previous studies filled the data gap by spatially interpolating neighboring PM(sub 2.5) measurements or predictions. This strategy ignored the effect of cloud cover on aerosol loadings and has been shown to exhibit poor performance when monitoring stations are sparse or when there is seasonal large-scale missngness. Using the Yangtze River Delta of China as an example, we present a Multiple Imputation (MI) method that combines the MAIAC high-resolution satellite retrievals with chemical transport model (CTM) simulations to fill missing AOD. A two-stage statistical model driven by gap-filled AOD, meteorology and land use information was then fitted to estimate daily ground PM(sub 2.5) concentrations in 2013 and 2014 at 1 km resolution with complete coverage in space and time. The daily MI models have an average R(exp 2) of 0.77, with an inter-quartile range of 0.71 to 0.82 across days. The overall Ml model 10-fold cross-validation R(exp 2) (root mean square error) were 0.81 (25 gm(exp 3)) and 0.73 (18 gm(exp 3)) for year 2013 and 2014, respectively. Predictions with only observational AOD or only imputed AOD showed similar accuracy.Comparing with previous gap-filling methods, our MI method presented in this study performed bette rwith higher coverage, higher accuracy, and the ability to fill missing PM(sub 2.5) predictions without ground PM(sub 2.5) measurements. This method can provide reliable PM(sub 2.5)predictions with complete coverage that can reduce biasin exposure assessment in air pollution and health studies.

Crustal structure revealed by a deep seismic sounding profile of Baijing-Gaoming-Jinwan in the Pearl River Delta

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Zhang, Xiang; Ye, Xiuwei; Lv, Jinshui; Sun, Jinlong; Wang, Xiaona

2018-02-01

The Pearl River Estuary area, located in the middle part of the southern China coastal seismic belt, has long been considered a potential source of strong earthquakes above magnitude 7.0. To scientifically assess the potential strong earthquake risk in this area, a three-dimensional artificial seismic sounding experiment, consisting of a receiving array and seabed seismograph, was performed to reveal the deep crustal structure in this region. We used artificial ship-borne air-gun excitation shots as sources, and fixed and mobile stations as receivers to record seismic data from May to August 2015. This paper presents results along a line from the western side of the Pearl River Estuary to the western side of the Baijing-Gaoming-Jinwan profile. A two-dimensional velocity structure was constructed using seismic travel-time tomography. The inversion results show that the Moho depth is 27 km in the coastal area and 30 km in the northwest of the Pearl River Estuary area, indicating that the crust thins from land to sea. Two structural discontinuities and multiple low-velocity anomalies appear in the crustal section. Inside both discontinuity zones, a low-velocity layer, with a minimum velocity of 6.05 km s-1, exists at a depth of about 15 km, and another, with a minimum velocity of 6.37 km s-1, exists at a depth of about 21.5 km between the middle and lower crust. These low velocities suggest that the discontinuities may consist of partly molten material. Earthquakes with magnitudes higher than 5.0 occurred in the low-velocity layer along the profile. The deep Kaiping-Enping fault, rooted in the crust, may be one of the most important channels for deep material upwelling and is related to tectonic movement since the Cretaceous in the Pearl River Delta tectonic rift basin.

Monitoring Ecological and Environmental Changes in Coastal Wetlands in the Yellow River Delta from 1987 to 2010 Using Remote Sensing Techniques

Science.gov (United States)

Shang, Kun; Zhao, Dong; Gan, Fuping; Xiao, Chenchao

2016-04-01

Many wetlands in the world have degraded rapidly in recent years, especially in China. The Yellow River Delta (YRD) is one of the largest deltas in China. The YRD Nature Reserve is one of China's most complete, broadest, and youngest wetland ecological systems in the warm-temperate zone. Most previous studies have placed particular emphasis on ecological environment or landscape of the YRD based on the distribution of wetlands. In recent years, with the rapid development of the city of Dongying, located in the YRD, the impacts of human activities are increasingly significant, so that monitoring changes in the wetlands has become especially important. In this research, we applied an improved Support Vector Machine (SVM) approach to wetland classification based on feature band set construction and optimization using seven Landsat images. By extracting waterlines, classifying wetlands and deriving landscape parameters, we have achieved high-frequency comprehensive monitoring of the wetlands in the YRD over a relatively long period. It offers a better estimate of wetland change trends than certain previous studies. From 1987 to 2010, the natural waterline primarily experienced erosion due to precipitation abnormalities, as well as coastal exploitation, as the co-analyzed meteorological data suggest. Meanwhile, the artificial waterline barely changed. The wetland area decreased rapidly from approximately 4,607 km2 to 2,714 km2 between 1987 and 2000. Ecological resilience and landscape diversity also decreased significantly during this period. The major impact factors were most likely urbanization, population expansion and the exploitation of the wetlands. After 2000, ecological resilience exhibited a positive trend. However, because newly built aquatic farms and salt works caused serious damages and threatened the natural beach landscape, the landscape fragmentation of muddy and sandy beaches increased after 2000. According to the results, more effective policies and

Assessing Light Pollution in China Based on Nighttime Light Imagery

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Wei Jiang

2017-02-01

Full Text Available Rapid urbanization and economic development inevitably lead to light pollution, which has become a universal environmental issue. In order to reveal the spatiotemporal patterns and evolvement rules of light pollution in China, images from 1992 to 2012 were selected from the Defense Meteorological Satellite Program Operational Linescan System (DMSP/OLS and systematically corrected to ensure consistency. Furthermore, we employed a linear regression trend method and nighttime light index method to demonstrate China’s light pollution characteristics across national, regional, and provincial scales, respectively. We found that: (1 China’s light pollution expanded significantly in provincial capital cities over the past 21 years and hot-spots of light pollution were located in the eastern coastal region. The Yangtze River Delta, Pearl River Delta, and Beijing–Tianjin–Hebei regions have formed light pollution stretch areas; (2 China’s light pollution was mainly focused in areas of north China (NC and east China (EC, which, together, accounted for over 50% of the light pollution for the whole country. The fastest growth of light pollution was observed in northwest China (NWC, followed by southwest China (SWC. The growth rates of east China (EC, central China (CC, and northeast China (NEC were stable, while those of north China (NC and south China (SC declined; (3 Light pollution at the provincial scale was mainly located in the Shandong, Guangdong, and Hebei provinces, whereas the fastest growth of light pollution was in Tibet and Hainan. However, light pollution levels in the developed provinces (Hong Kong, Macao, Shanghai, and Tianjin were higher than those of the undeveloped provinces. Similarly, the light pollution heterogeneities of Taiwan, Beijing, and Shanghai were higher than those of undeveloped western provinces.

Drivers, trends, and potential impacts of long-term coastal reclamation in China from 1985 to 2010

Energy Technology Data Exchange (ETDEWEB)

Tian, Bo; Wu, Wenting; Yang, Zhaoqing; Zhou, Yunxuan

2016-03-01

Driven by rapid economic development, population growth, and urbanization, China has experienced severe coastal land reclamation over the last decades, which resulted in significant loss of coastal wetland and wildlife habitat, and degradation of marine ecosystems. This study used advanced remote-sensing techniques to analyze the spatial and temporal distributions of coastal reclamation in China and investigated the relationships between coastal land reclamation and coastal economy, population growth, and urbanization. Analysis of long-term Landsat images time series from 1985 to 2010 in 5-year intervals, in combination with remotely sensed image techniques, indicated a sharp increasing trend of land reclamation after 2005, which accounted for over 35% of China’s total reclamation during the 25-year period since 1985. High-intensity coastal reclamation in China was mainly driven by the booming economy associated with urbanization and industrial development in the coastal region. Analysis indicated that coastal land reclamation is closely correlated with the GDP per capita in China. Study results of Landsat images showed that 754,697 ha of coastal wetlands have been reclaimed across all coastal provinces and metropolises from 1985 to 2010, at an annual rate of 5.9%. Coastal areas within the three major economic zones (Bohai Bay, Yangtze River Delta, and Pearl River Delta) were found to generally have higher reclamation rates. For example, the built-up area in Shanghai, which is located in the Yangtze River Delta, increased more than five times from 1985 to 2010. Approximately 35% of the reclamation occurred in Bohai Bay, in which the CRI between 2005 and 2010 was three times higher than the average CRI over the 25-year period.

The Dokka delta - consequences of water power development in the River Dokka

International Nuclear Information System (INIS)

Halvorsen, Gunnar; Sloreid, Svein-Erik; Walseng, Bjoern

1997-11-01

The report concerns an investigation done in Norway on environmental consequences of hydroelectric power development in the Dokka river. This development has reduced the water flow through the Dokka delta to about 50% of its natural level. The biological effect of the reduction has been studied in the period from 1987 to 1990, comprising two years before and two years after the reduction. Sedimentation, water chemistry, planktonic and littoral crustaceans and bottom fauna have been studied. 223 refs., 58 figs., 9 tabs

Spatially explicit assessment of heat health risk by using multi-sensor remote sensing images and socioeconomic data in Yangtze River Delta, China.

Science.gov (United States)

Chen, Qian; Ding, Mingjun; Yang, Xuchao; Hu, Kejia; Qi, Jiaguo

2018-05-25

The increase in the frequency and intensity of extreme heat events, which are potentially associated with climate change in the near future, highlights the importance of heat health risk assessment, a significant reference for heat-related death reduction and intervention. However, a spatiotemporal mismatch exists between gridded heat hazard and human exposure in risk assessment, which hinders the identification of high-risk areas at finer scales. A human settlement index integrated by nighttime light images, enhanced vegetation index, and digital elevation model data was utilized to assess the human exposure at high spatial resolution. Heat hazard and vulnerability index were generated by land surface temperature and demographic and socioeconomic census data, respectively. Spatially explicit assessment of heat health risk and its driving factors was conducted in the Yangtze River Delta (YRD), east China at 250 m pixel level. High-risk areas were mainly distributed in the urbanized areas of YRD, which were mostly driven by high human exposure and heat hazard index. In some less-urbanized cities and suburban and rural areas of mega-cities, the heat health risks are in second priority. The risks in some less-developed areas were high despite the low human exposure index because of high heat hazard and vulnerability index. This study illustrated a methodology for identifying high-risk areas by combining freely available multi-source data. Highly urbanized areas were considered hotspots of high heat health risks, which were largely driven by the increasing urban heat island effects and population density in urban areas. Repercussions of overheating were weakened due to the low social vulnerability in some central areas benefitting from the low proportion of sensitive population or the high level of socioeconomic development. By contrast, high social vulnerability intensifies heat health risks in some less-urbanized cities and suburban areas of mega-cities.

Speciated OVOC and VOC emission inventories and their implications for reactivity-based ozone control strategy in the Pearl River Delta region, China.

Science.gov (United States)

Ou, Jiamin; Zheng, Junyu; Li, Rongrong; Huang, Xiaobo; Zhong, Zhuangmin; Zhong, Liuju; Lin, Hui

2015-10-15

The increasing ground-ozone (O3) levels, accompanied by decreasing SO2, NO2, PM10 and PM2.5 concentrations benefited from air pollution control measures implemented in recent years, initiated a serious challenge to control Volatile Organic Compound (VOC) emissions in the Pearl River Delta (PRD) region, China. Speciated VOC emission inventory is fundamental for estimating Ozone Formation Potentials (OFPs) to identify key reactive VOC species and sources in order to formulate efficient O3 control strategies. With the use of the latest bulk VOC emission inventory and local source profiles, this study developed the PRD regional speciated Oxygenated Volatile Organic Compound (OVOC) and VOC emission inventories to identify the key emission-based and OFP-based VOC sources and species. Results showed that: (1) Methyl alcohol, acetone and ethyl acetate were the major constituents in the OVOC emissions from industrial solvents, household solvents, architectural paints and biogenic sources; (2) from the emission-based perspective, aromatics, alkanes, OVOCs and alkenes made up 39.2%, 28.2%, 15.9% and 10.9% of anthropogenic VOCs; (3) from the OFP-based perspective, aromatics and alkenes become predominant with contributions of 59.4% and 25.8% respectively; (4) ethene, m/p-xylene, toluene, 1,2,4-trimethyl benzene and other 24 high OFP-contributing species were the key reactive species that contributed to 52% of anthropogenic emissions and up to 80% of OFPs; and (5) industrial solvents, industrial process, gasoline vehicles and motorcycles were major emission sources of these key reactive species. Policy implications for O3 control strategy were discussed. The OFP cap was proposed to regulate VOC control policies in the PRD region due to its flexibility in reducing the overall OFP of VOC emission sources in practice. Copyright © 2015 Elsevier B.V. All rights reserved.

Integrated Studies of a Regional Ozone Pollution Synthetically Affected by Subtropical High and Typhoon System in the Yangtze River Delta Region, China

Science.gov (United States)

Xie, M.; Shu, L.

2017-12-01

Severe high ozone (O3) episodes usually have close relations to synoptic systems. A regional continuous O3 pollution episode was detected over the Yangtze River Delta (YRD) region in China during August 7-12, 2013, in which the O3 concentrations in more than half of the cities exceeded the national air quality standard. By means of the observational analysis and the WRF/CMAQ numerical simulation, the characteristics and the essential impact factors of the typical regional O3 pollution are investigated. The observational analysis shows that the atmospheric subsidence dominated by Western Pacific subtropical high plays a crucial role in the formation of high-level O3. In addition, when the YRD cities at the front of Typhoon Utor, the periphery circulation of typhoon system can enhance the downward airflows and cause more serious air pollution. But when the typhoon system weakens the subtropical high, the prevailing southeasterly surface wind leads to the mitigation of the O3 pollution. The Integrated Process Rate (IPR) analysis incorporated in CMAQ is applied to further illustrate the combined influence of subtropical high and typhoon system in this O3 episode. The results show that the vertical diffusion (VDIF) and the gas-phase chemistry (CHEM) are two major contributors to O3 formation. On August 10-11, the cities close to the sea are apparently affected by the typhoon system, with the contribution of VDIF increasing to 28.45 ppb/h in Shanghai and 19.76 ppb/h in Hangzhou. When the YRD region is under the control of the typhoon system, the contribution values of all individual processes decrease to a low level in all cities. These results provide an insight for the O3 pollution synthetically impacted by the Western Pacific subtropical high and the tropical cyclone system.

A modelling framework to project future climate change impacts on streamflow variability and extremes in the West River, China

Directory of Open Access Journals (Sweden)

Y. Fei

2014-09-01

Full Text Available In this study, a hydrological modelling framework was introduced to assess the climate change impacts on future river flow in the West River basin, China, especially on streamflow variability and extremes. The modelling framework includes a delta-change method with the quantile-mapping technique to construct future climate forcings on the basis of observed meteorological data and the downscaled climate model outputs. This method is able to retain the signals of extreme weather events, as projected by climate models, in the constructed future forcing scenarios. Fed with the historical and future forcing data, a large-scale hydrologic model (the Variable Infiltration Capacity model, VIC was executed for streamflow simulations and projections at daily time scales. A bootstrapping resample approach was used as an indirect alternative to test the equality of means, standard deviations and the coefficients of variation for the baseline and future streamflow time series, and to assess the future changes in flood return levels. The West River basin case study confirms that the introduced modelling framework is an efficient effective tool to quantify streamflow variability and extremes in response to future climate change.

Mapping Soil Carbon in the Yukon Kuskokwim River Delta Alaska

Science.gov (United States)

Natali, S.; Fiske, G.; Schade, J. D.; Mann, P. J.; Holmes, R. M.; Ludwig, S.; Melton, S.; Sae-lim, N.; Jardine, L. E.; Navarro-Perez, E.

2017-12-01

Arctic river deltas are hotspots for carbon storage, occupying 10% of carbon stored in arctic permafrost. The Yukon Kuskokwim (YK) Delta, Alaska is located in the lower latitudinal range of the northern permafrost region in an area of relatively warm permafrost that is particularly vulnerable to warming climate. Active layer depths range from 50 cm on peat plateaus to >100 cm in wetland and aquatic ecosystems. The size of the soil organic carbon pool and vulnerability of the carbon in the YK Delta is a major unknown and is critically important as climate warming and increasing fire frequency may make this carbon vulnerable to transport to aquatic and marine systems and the atmosphere. To characterize the size and distribution of soil carbon pools in the YK Delta, we mapped the land cover of a 1910 km2 watershed located in a region of the YK Delta that was impacted by fire in 2015. The map product was the result of an unsupervised classification using the Weka K Means clustering algorithm implemented in Google's Earth Engine. Inputs to the classification were Worldview2 resolution optical imagery (1m), Arctic DEM (5m), and Sentinel 2 level 1C multispectral imagery, including NDVI, (10 m). We collected 100 soil cores (0-30 cm) from sites of different land cover and landscape position, including moist and dry peat plateaus, high and low intensity burned plateaus, fens, and drained lakes; 13 lake sediment cores (0-50 cm); and 20 surface permafrost cores (to 100 cm) from burned and unburned peat plateaus. Active layer and permafrost soils were analyzed for organic matter content, soil moisture content, and carbon and nitrogen pools (30 and 100 cm). Soil carbon content varied across the landscape; average carbon content values for lake sediments were 12% (5- 17% range), fens 26% (9-44%), unburned peat plateaus 41% (34-44%), burned peat plateaus 19% (7-34%). These values will be used to estimate soil carbon pools, which will be applied to the spatial extent of each

The forecasting research of early warning systems for atmospheric pollutants: A case in Yangtze River Delta region

Science.gov (United States)

Song, Yiliao; Qin, Shanshan; Qu, Jiansheng; Liu, Feng

2015-10-01

The issue of air quality regarding PM pollution levels in China is a focus of public attention. To address that issue, to date, a series of studies is in progress, including PM monitoring programs, PM source apportionment, and the enactment of new ambient air quality index standards. However, related research concerning computer modeling for PM future trends estimation is rare, despite its significance to forecasting and early warning systems. Thereby, a study regarding deterministic and interval forecasts of PM is performed. In this study, data on hourly and 12 h-averaged air pollutants are applied to forecast PM concentrations within the Yangtze River Delta (YRD) region of China. The characteristics of PM emissions have been primarily examined and analyzed using different distribution functions. To improve the distribution fitting that is crucial for estimating PM levels, an artificial intelligence algorithm is incorporated to select the optimal parameters. Following that step, an ANF model is used to conduct deterministic forecasts of PM. With the identified distributions and deterministic forecasts, different levels of PM intervals are estimated. The results indicate that the lognormal or gamma distributions are highly representative of the recorded PM data with a goodness-of-fit R2 of approximately 0.998. Furthermore, the results of the evaluation metrics (MSE, MAPE and CP, AW) also show high accuracy within the deterministic and interval forecasts of PM, indicating that this method enables the informative and effective quantification of future PM trends.

Seasonal Characteristics of Widespread Ozone Pollution in China and India: Current Model Capabilities and Source Attributions

Science.gov (United States)

Gao, M.; Song, S.; Beig, G.; Zhang, H.; Hu, J.; Ying, Q.; McElroy, M. B.

2017-12-01

Fast urbanization and industrialization in China and India have led to severe ozone pollution, threatening public health in these densely populated countries. We show the spatial and seasonal characteristics of ozone concentrations using nation-wide observations for these two countries in 2013. We used the Weather Research and Forecasting model coupled to chemistry (WRF-Chem) to conduct one-year simulations and to evaluate how current models capture the important photochemical processes using the exhaustive available datasets in China and India, including surface measurements, ozonesonde data and satellite retrievals. We also employed the factor separation approach to distinguish the contributions of different sectors to ozone during different seasons. The back trajectory model FLEXPART was applied to investigate the role of transport in highly polluted regions (e.g., North China Plain, Yangtze River delta, and Pearl River Delta) during different seasons. Preliminary results indicate that the WRF-Chem model provides a satisfactory representation of the temporal and spatial variations of ozone for both China and India. The factor separation approach offers valuable insights into relevant sources of ozone for both countries providing valuable guidance for policy options designed to mitigate the related problem.

Magnetic minerals in three Asian rivers draining into the South China Sea: Pearl, Red, and Mekong Rivers

Science.gov (United States)

Kissel, Catherine; Liu, Zhifei; Li, Jinhua; Wandres, Camille

2016-05-01

The use of the marine sedimentary magnetic properties, as tracers for changes in precipitation rate and in oceanic water masses transport and exchanges, implies to identify and to characterize the different sources of the detrital fraction. This is of particular importance in closed and/or marginal seas such as the South China Sea. We report on the magnetic properties of sedimentary samples collected in three main Asian rivers draining into the South China Sea: the Pearl, Red, and Mekong Rivers. The geological formations as well as the present climatic conditions are different from one catchment to another. The entire set of performed magnetic analyses (low-field magnetic susceptibility, ARM acquisition and decay, IRM acquisition and decay, back-field acquisition, thermal demagnetization of three-axes IRM, hysteresis parameters, FORC diagrams, and low-temperature magnetic measurements) allow us to identify the magnetic mineralogy and the grain-size distribution when magnetite is dominant. Some degree of variability is observed in each basin, illustrating different parent rocks and degree of weathering. On average it appears that the Pearl River is rich in magnetite along the main stream while the Mekong River is rich in hematite. The Red River is a mixture of the two. Compared to clay mineral assemblages and major element contents previously determined on the same samples, these new findings indicate that the magnetic fraction brings complementary information of great interest for environmental reconstructions based on marine sediments from the South China Sea.

The impact of Cyclone Nargis on the Ayeyarwady (Irrawaddy) River delta shoreline and nearshore zone (Myanmar): Towards degraded delta resilience?

Science.gov (United States)

Besset, Manon; Anthony, Edward J.; Dussouillez, Philippe; Goichot, Marc

2017-10-01

The Ayeyarwady River delta (Myanmar) is exposed to tropical cyclones, of which the most devastating has been cyclone Nargis (2-4 May 2008). We analysed waves, flooded area, nearshore suspended sediments, and shoreline change from satellite images. Suspended sediment concentrations up to 40% above average during the cyclone may reflect fluvial mud supply following heavy rainfall and wave reworking of shoreface mud. Massive recession of the high-water line resulted from backshore flooding by cyclone surge. The shoreline showed a mean retreat of 47 m following Nargis. Erosion was stronger afterwards (-148 m between August 2008 and April 2010), largely exceeding rates prior to Nargis (2000-2005: -2.14 m/year) and over 41 years (1974-2015: -0.62 m/year). This implies that resilience was weak following cyclone impact. Consequently, the increasingly more populous Ayeyarwady delta, rendered more and more vulnerable by decreasing fluvial sediment supply, could, potentially, become more severely impacted by future high-energy events.

Potential plant species distribution in the Yellow River Delta under the influence of groundwater level and soil salinity

NARCIS (Netherlands)

Fan Xiaomei,; Pedroli, B.; Liu Gaohuan,; Liu Hongguang,; Song Chuangye,; Shu Longcang,

2011-01-01

This article describes a multidisciplinary approach to assessing potential vegetation types. The relation between vegetation distribution as derived from field survey and habitat characteristics in the Yellow River Delta (YRD) was analyzed using detrended canonical correspondence analysis (DCCA).

Using delta15N- and delta18O-values to identify nitrate sources in karst ground water, Guiyang, southwest China.

Science.gov (United States)

Liu, Cong-Qiang; Li, Si-Liang; Lang, Yun-Chao; Xiao, Hua-Yun

2006-11-15

Nitrate pollution of the karstic groundwater is an increasingly serious problem with the development of Guiyang, the capital city of Guizhou Province, southwest China. The higher content of NO3- in groundwater compared to surface water during both summer and winter seasons indicates that the karstic groundwater system cannot easily recover once contaminated with nitrate. In order to assess the sources and conversion of nitrate in the groundwater of Guiyang, we analyzed the major ions, delta(15)N-NH4+, delta(15)N-NO3-, and delta(18)O-NO3- in surface and groundwater samples collected during both summer and winter seasons. The results show that nitrate is the major dominant species of nitrogen in most water samples and there is a big variation of nitrate sources in groundwater between winter and summer season, due to fast response of groundwater to rain or surface water in the karst area. Combined with information on NO3- /Cl-, the variations of the isotope values of nitrate in the groundwater show a mixing process of multiple sources of nitrate, especially in the summer season. Chemical fertilizer and nitrification of nitrogen-containing organic materials contribute nitrate to suburban groundwater, while the sewage effluents and denitrification mainly control the nitrate distribution in urban groundwater.

[Distribution characteristics of soil organic carbon and its composition in Suaeda salsa wetland in the Yellow River delta].

Science.gov (United States)

Dong, Hong-Fang; Yu, Jun-Bao; Guan, Bo

2013-01-01

Applying the method of physical fractionation, distribution characteristics of soil organic carbon and its composition in Suaeda salsa wetland in the Yellow River delta were studied. The results showed that the heavy fraction organic carbon was the dominant component of soil organic carbon in the studied region. There was a significantly positive relationship between the content of heavy fraction organic carbon, particulate organic carbon and total soil organic carbon. The ranges of soil light fraction organic carbon ratio and content were 0.008% - 0.15% and 0.10-0.40 g x kg(-1), respectively, and the range of particulate organic carbon ratio was 8.83% - 30.58%, indicating that the non-protection component of soil organic carbon was low and the carbon pool was relatively stable in Suaeda salsa wetland of the Yellow River delta.

Documented changes in annual runoff and attribution since the 1950s within selected rivers in China

Directory of Open Access Journals (Sweden)

Lü-Liu Liu

2017-03-01

Full Text Available To enable local water resource management and maintenance of ecosystem integrity and to protect and mitigate against flood and drought, it is necessary to determine changes in long-term series of streamflow and to distinguish the roles that climate change and human disturbance play in these changes. A review of previous research on the detection and attribution of observed changes in annual runoff in China shows a decrease in annual runoff since the 1950s in northern China in areas such as the Songhuajiang River water resources zone, the Liaohe River water resources zone, the Haihe River water resources zone, the Yellow River water resources zone, and the Huaihe River water resources Zone. Furthermore, abrupt changes in annual runoff occurred mostly in the 1970s and 1980s in all the above zones, except for some of the sub-basins in the middle Yellow River where abrupt change occurred in the 1990s. Changes in annual runoff are found to be mainly caused by climate change in the western Songhuajiang River basin, the upper mainstream of the Yangtze River, and the western Pearl River basin, which shows that studies on the impact of climate change on future water resources under different climate change scenarios are required to enable planning and management by agencies in these river basins. However, changes in annual runoff were found to be mainly caused by human activities in most of the catchments in northern China (such as the southern Songhuajiang River, Liaohe River, Haihe River, the lower reach and some of the catchments within the middle Yellow River basin and in middle-eastern China, such as the Huaihe River and lower mainstream of the Yangtze River. This suggests that current hydro-climatic data can continue to be used in water-use planning and that policymakers need to focus on water resource management and protection.

Process analysis of regional aerosol pollution during spring in the Pearl River Delta region, China

Science.gov (United States)

Fan, Qi; Lan, Jing; Liu, Yiming; Wang, Xuemei; Chan, Pakwai; Hong, Yingying; Feng, Yerong; Liu, Yexin; Zeng, Yanjun; Liang, Guixiong

2015-12-01

A numerical simulation analysis was performed for three air pollution episodes in the Pearl River Delta (PRD) region during March 2012 using the third-generation air quality modeling system Models-3/CMAQ. The results demonstrated that particulate matter was the primary pollutant for all three pollution episodes and was accompanied by relatively low visibility in the first two episodes. Weather maps indicate that the first two episodes occurred under the influence of warm, wet southerly air flow systems that led to high humidity throughout the region. The liquid phase reaction of gaseous pollutants resulted in the generation of fine secondary particles, which were identified as the primary source of pollution in the first two episodes. The third pollution episode occurred during a warming period following a cold front. Relative humidity was lower during this episode, and coarse particles were the major pollution contributor. Results of process analysis indicated that emissions sources, horizontal transport and vertical transport were the primary factors affecting pollutant concentrations within the near-surface layer during all three episodes, while aerosol processes, cloud processes, horizontal transport and vertical transport had greater influence at approximately 900 m above ground. Cloud processes had a greater impact during the first two pollution episodes because of the higher relative humidity. In addition, by comparing pollution processes from different cities (Guangzhou and Zhongshan), the study revealed that the first two pollution episodes were the result of local emissions within the PRD region and transport between surrounding cities, while the third episode exhibited prominent regional pollution characteristics and was the result of regional pollutant transport.

Innovation in monitoring: The U.S. Geological Survey Sacramento–San Joaquin River Delta, California, flow-station network

Science.gov (United States)

Burau, Jon; Ruhl, Cathy; Work, Paul A.

2016-01-29

The U.S. Geological Survey (USGS) installed the first gage to measure the flow of water into California’s Sacramento–San Joaquin River Delta from the Sacramento River in the late 1800s. Today, a network of 35 hydro-acoustic meters measure flow throughout the delta. This region is a critical part of California’s freshwater supply and conveyance system. With the data provided by this flow-station network—sampled every 15 minutes and updated to the web every hour—state and federal water managers make daily decisions about how much freshwater can be pumped for human use, at which locations, and when. Fish and wildlife scientists, working with water managers, also use this information to protect fish species affected by pumping and loss of habitat. The data are also used to help determine the success or failure of efforts to restore ecosystem processes in what has been called the “most managed and highly altered” watershed in the country.

Tropospheric aerosols radiation feedback on the climate of Pearl River Delta Region using an air quality model

Science.gov (United States)

Nduka, I. C.

2016-12-01

The Pearl River Delta (PRD) region, one of the most vibrant economic regions in China has been witnessing rapid population, economic and structural growth and development. It is also one of the regions mostly polluted with trace gases and particulates. Recent reviews show large uncertainties in climate modification studies, indicating the need for further investigations, such as the role of tropospheric aerosols on direct and indirect climate modification. The aim of this research is to appraise the impacts of tropospheric aerosols on the climate of PRD region. An integrated air quality downscale meteorology and air quality from regional scale (27km) to local scale (3km). The model will be evaluated for both meteorology and air quality by comparing model results with measurements. The radiative forcing of tropospheric aerosols will also be determined so as to estimate the feedbacks and impacts on the climate. This research, when completed, is expected to improve our understanding of tropospheric aerosol-cloud thermodynamic interactions at regional and local scales, thus enhancing our knowledge of the regional and local climate system, which is anticipated to provide critical references for formulating sustainable environment and air quality policies.

COMPLEX NETWORK SIMULATION OF FOREST NETWORK SPATIAL PATTERN IN PEARL RIVER DELTA

Directory of Open Access Journals (Sweden)

Y. Zeng

2017-09-01

Full Text Available Forest network-construction uses for the method and model with the scale-free features of complex network theory based on random graph theory and dynamic network nodes which show a power-law distribution phenomenon. The model is suitable for ecological disturbance by larger ecological landscape Pearl River Delta consistent recovery. Remote sensing and GIS spatial data are available through the latest forest patches. A standard scale-free network node distribution model calculates the area of forest network’s power-law distribution parameter value size; The recent existing forest polygons which are defined as nodes can compute the network nodes decaying index value of the network’s degree distribution. The parameters of forest network are picked up then make a spatial transition to GIS real world models. Hence the connection is automatically generated by minimizing the ecological corridor by the least cost rule between the near nodes. Based on scale-free network node distribution requirements, select the number compared with less, a huge point of aggregation as a future forest planning network’s main node, and put them with the existing node sequence comparison. By this theory, the forest ecological projects in the past avoid being fragmented, scattered disorderly phenomena. The previous regular forest networks can be reduced the required forest planting costs by this method. For ecological restoration of tropical and subtropical in south China areas, it will provide an effective method for the forest entering city project guidance and demonstration with other ecological networks (water, climate network, etc. for networking a standard and base datum.

Influence of agricultural practice on trace metals in soils and vegetation in the water conservation area along the East River (Dongjiang River), South China

Energy Technology Data Exchange (ETDEWEB)

Luo, Chunling, E-mail: clluo@gig.ac.cn [Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou 510640 (China); Yang, Renxiu [Department of Civil and Structural Engineering, The Hong Kong Polytechnic University, Hung Hom, Kowloon (Hong Kong); Wang, Yan; Li, Jun; Zhang, Gan [Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou 510640 (China); Li, Xiangdong [Department of Civil and Structural Engineering, The Hong Kong Polytechnic University, Hung Hom, Kowloon (Hong Kong)

2012-08-01

Dongjiang (East River) is the key resource of potable water for the Pearl River Delta region, South China. Although industrial activities are limited in the water conservation area along this river, agriculture is very intensive. The present study evaluated trace metals in four soils under different cultivation. The total concentrations of trace metals decreased in the order orchard soil > vegetable soil > paddy soil > natural soil, reflecting decreasing inputs of agrochemicals to soils. Relatively high concentrations of Cd were recorded in the 60-cm soil profiles. The {sup 206}Pb/{sup 207}Pb ratio in the above-ground tissues of plant was significantly lower than their corresponding soils. In combination with the low transfer factor of Pb from soil to plant shoots, atmospheric deposition is probably a major pathway for Pb to enter plant leaves. Regular monitoring on the soil quality in this area is recommended for the safety of water resource and agricultural products. - Highlights: Black-Right-Pointing-Pointer Soil Cd exceeded the upper limit of Chinese standard for agricultural soils. Black-Right-Pointing-Pointer Relatively high concentrations of Cd were recorded in the 60-cm soil profiles. Black-Right-Pointing-Pointer Agricultural soil had higher concentrations of metals and lower {sup 206}Pb/{sup 207}Pb ratios. Black-Right-Pointing-Pointer Pb in above-ground tissues of plant was more anthropogenic than soil. Black-Right-Pointing-Pointer Atmospheric deposition may be a major pathway for Pb to enter plant leaves.

[Investigation on sanitation of freshwater aquaculture environments and Clonorchis sinensis intermediate host infection in a city of Pearl River Delta region, China].

Science.gov (United States)

Man, Wang; Le, Luo; Xue-Qin, Chen; Lei, Li; Yue-Yi, Fang

2017-10-19

To understand the current status of the sanitation of freshwater aquaculture environments, and Clonorchis sinensis infection of freshwater fish in the aquaculture and market in a city of Pearl River Delta region, so as to provide the evidence for formulating the prevention and control strategy of clonorchiasis sinensis. In 2016, based on the distribution of freshwater aquaculture, 36 freshwater fish ponds among 14 towns were selected for sampling and investigation, and 10-20 pieces were collected from each pond. Besides, 3 aquatic product wholesale markets were included, among which 3-6 stalls were selected from each market, and 20-30 pieces were collected from each stall. The metacercaria in the fish was examined by the digestion method. In the 36 fish ponds, there were no toilets with the stool being drained into fish ponds directly, and there was only one pond with duck sheds with the stool being drained into fish ponds directly. Totally 437 pieces of freshwater fish from ponds were detected, with a metacercaria positive rate of 4.35% (19/437). The metacercaria positive fish were distributed in 50% (7/14) of towns and 25% (9/36) ponds. The positive rates of crucian carp, grass carp, dace, aristichthysnobilis, and tilapia were 13.95% (6/43), 4.76% (9/189), 4.44 (2/45), 1.55% (2/129), and 0 (0/31) respectively, with statistically significant difference ( χ 2 = 13.46, P = 0.01). Totally 307 pieces of freshwater fish were collected from the wholesale markets, with a total positive rate of 1.95% (6/307). The positive rate of grass carp and aristichthysnobilis were 3.20% (4/125) and 2.78% (2/72) respectively, and no positive samples were found in crucian carp, dace and tilapia, with no statistically significant difference among the different fish in the infection rate (Fisher exact P = 0.75). The sanitation of freshwater aquaculture environments in a city of Pearl River Delta region is relative good. However, there are different degrees of Clonorchis sinensis

Changing Course - the Baird Team Solution: a Delta for All

Science.gov (United States)

Nairn, R. B.

2016-02-01

The Changing Course Design competition was initiated to evaluate options for re-positioning the mouth of the Mississippi River and modifying the management of the Lower Mississippi River to support the 2017 Master Plan for the Louisiana coast. This paper will present the findings of one of the selected competitors: the Baird Team and their "Delta for All" approach. A key to success in the future management of the lower Mississippi River is the development of an integrated, holistic approach to management that recognizes the need to harness the full land/wetland building and restorative potential of the river at the same time as improving flood protection and navigation. Fundamentally the Baird solution recognized the underlying geomorphic challenges of the Delta: it receives three to four times less sediment from the Mississippi River than it did historically and sea level is rising two to three times faster than it did historically and is predicted to rise much faster in the future. The result will be a smaller delta in the future. Our approach seeks to harness as close to 100% of the land building potential of the river to make the smaller future delta as large as possible. This compares to the 2012 State Master Plan which would harness approximately 50% of the land-building potential. Our approach also recognizes that the further inland new distributary mouths and associated sub-deltas are located, the greater the delta building potential. Our approach builds with the river by creating and managing new river distributaries that are opened and closed every 50 years or so to build new sub-deltas within a defined sustainable delta footprint. By placing the last outlet somewhere in the vicinity of English Turn the lower Mississippi River would become a tidal channel. These two simple concepts of harnessing 100% of the river and placing the last outlet near English Turn result in immediate and significant benefits for flood protection and navigation. Through the

Assessing subaqueous mudslide hazard on the Mississippi River delta front, Part 2: Insights revealed through high-resolution geophysical surveying

Science.gov (United States)

Obelcz, J.; Xu, K.; Bentley, S. J.; Georgiou, I. Y.; Maloney, J. M.; Miner, M. D.; Hanegan, K.; Keller, G.

2014-12-01

The northern Gulf of Mexico, including the subaqueous Mississippi River delta front (MRDF), has been productive for oil and gas development since the early 1900s. In 1969 cyclic seafloor wave loading associated with the passage of Hurricane Camille triggered subaqueous mudflows across the MRDF, destroying several offshore oil platforms. This incident spurred geophysical and geotechnical studies of the MRDF, which found that the delta front is prone to mass failures on gentle gradients (gas production, and (3) the frequent passage of tropical cyclones. In June 2014, a geophysical pilot study was conducted 8 km southwest of Southwest Pass, the distributary that currently receives the largest fraction of Mississippi River sediment supply. The resultant dataset encompasses 216 km of subbottom Chirp seismic profiles and a 60 km2 grid of bathymetry and sidescan data. Preliminary interpretation of these data shows the survey area can be classified into four primary sedimentary facies: mudflow gullies, mudflow lobes, undisturbed prodelta, and undisturbed delta front. Subbottom profiles reveal extensive biogenic gas from 20 to about 80 m water depths on the delta front; sidescan data show a variety of bottleneck slides, mudflow gullies and mudflow noses. Previous studies have attempted to constrain the periodicity and magnitude of subaqueous mudslides on the MRDF. However, large age gaps and varied resolution between datasets result in ambiguity regarding the cause and magnitude of observed bathymetric changes. We present high-temporal resolution MRDF bathymetric variations from 2005 (post Hurricane Katrina), 2009 (relatively quiescent storm period), and 2014 (post 2011 Mississippi River flood). These data yield better magnitude and timing estimates of mass movements. This exercise represents a first step towards (1) assembling a comprehensive geologic dataset upon which future MRDF geohazard assessments can be founded, and (2) understanding the dynamics of a massive

More frequent flooding? Changes in flood frequency in the Pearl River basin, China, since 1951 and over the past 1000 years

Science.gov (United States)

Zhang, Qiang; Gu, Xihui; Singh, Vijay P.; Shi, Peijun; Sun, Peng

2018-05-01

Flood risks across the Pearl River basin, China, were evaluated using a peak flood flow dataset covering a period of 1951-2014 from 78 stations and historical flood records of the past 1000 years. The generalized extreme value (GEV) model and the kernel estimation method were used to evaluate frequencies and risks of hazardous flood events. Results indicated that (1) no abrupt changes or significant trends could be detected in peak flood flow series at most of the stations, and only 16 out of 78 stations exhibited significant peak flood flow changes with change points around 1990. Peak flood flow in the West River basin increased and significant increasing trends were identified during 1981-2010; decreasing peak flood flow was found in coastal regions and significant trends were observed during 1951-2014 and 1966-2014. (2) The largest three flood events were found to cluster in both space and time. Generally, basin-scale flood hazards can be expected in the West and North River basins. (3) The occurrence rate of floods increased in the middle Pearl River basin but decreased in the lower Pearl River basin. However, hazardous flood events were observed in the middle and lower Pearl River basin, and this is particularly true for the past 100 years. However, precipitation extremes were subject to moderate variations and human activities, such as building of levees, channelization of river systems, and rapid urbanization; these were the factors behind the amplification of floods in the middle and lower Pearl River basin, posing serious challenges for developing measures of mitigation of flood hazards in the lower Pearl River basin, particularly the Pearl River Delta (PRD) region.

Benthic sediment data from eleven stations in the Mobile-Tensaw River Delta, Alabama on 17 June 1981 (NODC Accession 0118497)

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — Benthic sediment samples were collected from eleven stations in the Mobile-Tensaw River Delta on 17 June 1981. Samples were analyzed for particle size distribution...

Sediment-hosted contaminants and distribution patterns in the Mississippi and Atchafalaya River Deltas

Science.gov (United States)

Flocks, James G.; Kindinger, Jack G.; Ferina, Nicholas; Dreher, Chandra

2002-01-01

The Mississippi and Atchafalaya Rivers transport very large amounts of bedload and suspended sediments to the deltaic and coastal environments of the northern Gulf of Mexico. Absorbed onto these sediments are contaminants that may be detrimental to the environment. To adequately assess the impact of these contaminants it is first necessary to develop an understanding of sediment distribution patterns in these deltaic systems. The distribution patterns are defined by deltaic progradational cycles. Once these patterns are identified, the natural and industrial contaminant inventories and their depositional histories can be reconstructed. Delta progradation is a function of sediment discharge, as well as channel and receiving-basin dimensions. Fluvial energy controls the sediment distribution pattern, resulting in a coarse grained or sandy framework, infilled with finer grained material occupying the overbank, interdistributary bays, wetlands and abandoned channels. It has been shown that these fine-grained sediments can carry contaminants through absorption and intern them in the sediment column or redistribute them depending on progradation or degradation of the delta deposit. Sediment distribution patterns in delta complexes can be determined through high-resolution geophysical surveys and groundtruthed with direct sampling. In the Atchafalaya and Mississippi deltas, remote sensing using High-Resolution Single-Channel Seismic Profiling (HRSP) and Sidescan Sonar was correlated to 20-ft vibracores to develop a near-surface geologic framework that identifies variability in recent sediment distribution patterns. The surveys identified bedload sand waves, abandoned-channel back-fill, prodelta and distributary mouth bars within the most recently active portions of the deltas. These depositional features respond to changes in deltaic processes and through their response may intern or transport absorbed contaminants. Characterizing these features provides insight into the

Permafrost Organic Carbon Mobilization From the Watershed to the Colville River Delta: Evidence From 14C Ramped Pyrolysis and Lignin Biomarkers

Science.gov (United States)

Zhang, Xiaowen; Bianchi, Thomas S.; Cui, Xingqian; Rosenheim, Brad E.; Ping, Chien-Lu; Hanna, Andrea J. M.; Kanevskiy, Mikhail; Schreiner, Kathryn M.; Allison, Mead A.

2017-11-01

The deposition of terrestrial-derived permafrost particulate organic carbon (POC) has been recorded in major Arctic river deltas. However, associated transport pathways of permafrost POC from the watershed to the coast have not been well constrained. Here we utilized a combination of ramped pyrolysis-oxidation radiocarbon analysis (RPO 14C) along with lignin biomarkers, to track the linkages between soils and river and delta sediments. Surface and deep soils showed distinct RPO thermographs which may be related to degradation and organo-mineral interaction. Soil material in the bed load of the river channel was mostly derived from deep old permafrost. Both surface and deep soils were transported and deposited to the coast. Hydrodynamic sorting and barrier island protection played important roles in terrestrial-derived permafrost POC deposition near the coast. On a large scale, ice processes (e.g., ice gauging and strudel scour) and ocean currents controlled the transport and distribution of permafrost POC on the Beaufort Shelf.

[Variations and simulation of stable isotopes in precipitation in the Heihe River basin].

Science.gov (United States)

Wu, Jin-Kui; Yang, Qi-Yue; Ding, Yong-Jian; Ye, Bai-Sheng; Zhang, Ming-Quan

2011-07-01

To study the variations of deltaD and delta18O in precipitation, 301 samples were sampled during 2002-2004 in 6 sites in the Heihe River basin, Northwestern China. The deltaD and delta18O values ranged from 59 per thousand to -254 per thousand and 6.5 per thousand to -33.4 per thousand, respectively. This wide range indicated that stable isotopes in precipitation were controlled by different condensation mechanisms as a function of air temperature and varying sources of moisture. delta18O in precipitation had a close positive relationship with the air temperature, i. e., a clear temperature effect existed in this area. At a monthly scale, no precipitation effect existed. On the other hand, a weak precipitation effect still accrued at precipitation events scale. The spatial variation of delta18O showed that the weighted average delta18O values decreased with the increasing altitude of sampling sites at a gradient of -0. 47 per thousand/100m. A regional Meteoric Water Line, deltaD = 7.82 delta18O + 7.63, was nearly identical to the Meteoric Water Line in the Northern China. The results of backward trajectory of each precipitation day at Xishui showed that the moisture of the precipitation in cold season (October to March) mainly originated from the west while the moisture source was more complicated in warm season (April to September). The simulation of seasonal delta18O variation showed that the stable isotope composition of precipitation tended to a clear sine-wave seasonal variation.

Mixing state of ambient aerosols during different fog-haze pollution episodes in the Yangtze River Delta, China

Science.gov (United States)

Hu, Rui; Wang, Honglei; Yin, Yan; Chen, Kui; Zhu, Bin; Zhang, Zefeng; Kang, Hui; Shen, Lijuan

2018-04-01

The mixing state of aerosol particles were investigated using a single particle aerosol mass spectrometer (SPAMS) during a regional fog-haze episode in the Yangtze River Delta (YRD) on 16-28 Dec., 2015. The aerosols were analyzed and clustered into 12 classes: aged elemental carbon (Aged-EC), internally mixed organics and elemental carbon (ECOC), organic carbon (OC), Biomass, Amine, Ammonium, Na-K, V-rich, Pb-rich, Cu-rich, Fe-rich and Dust. Results showed that particles in short-term rainfalls mixed with more nitrate and oxidized organics, while they mixed with more ammonium and sulfate in long-term rainfall. Due to anthropogenic activities, stronger winds and solar radiation, the particle counts increased and the size ranges of particles broadened in haze. Carbonaceous particles and Na-K mixed with enhanced secondary species during haze, and obviously were more acidic, especially for the ones with a size range of 0.6-1.2 μm. For local and long-range transported pollution, OC had distinct size distributions while the changes of ECOC were uniform. The secondary formation of ECOC contributed significantly in local pollution and affected much smaller particles (as small as 0.5 μm) in long-range transported pollution. And long-range transported pollution was more helpful for the growth of OC. Particles mixed with more chloride and nitrate/sulfate in local/long-range transported pollution.

Sea Reclamation Status of Countries around the South China Sea from 1975 to 2010

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Junjue Zhang

2017-05-01

Full Text Available As a way of turning sea into land for living space for humans, the actions of sea reclamation bring about significant benefits. Nevertheless, it is also an under-recognized threat to the environment and the marine ecosystem. Based on images in two periods, sea reclamation information of countries around the South China Sea was extracted from 1975 to 2010. The spatial state and driven forces of sea reclamation are then discussed. Results show that the overall strength of sea reclamation in the South China Sea was great. New reclaimed land added up to 3264 km2. Sea reclamation for fish farming was the main reclamation type and widely distributed in the whole area, especially on the coast from the Pearl River Delta to the Red River Delta, and the coast of Ca Mau Peninsula. Sea reclamation in China and Vietnam was rather significant, which occupies 80.6% of the total reclamation area. Singapore had the highest level of sea reclamation. New reclaimed land for fish farming holds a key role in China, Vietnam, and Indonesia, while new reclaimed land for construction and docks dominated in Malaysia, Singapore, and Brunei. Areas and use-type compositions of new reclaimed land in countries varied greatly due to the differences of economic factors, policy inclination, and landscapes in the respective countries.

Mixing state of oxalic acid containing particles in the rural area of Pearl River Delta, China: implications for the formation mechanism of oxalic acid

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C. Cheng

2017-08-01

Full Text Available The formation of oxalic acid and its mixing state in atmospheric particulate matter (PM were studied using a single-particle aerosol mass spectrometer (SPAMS in the summer and winter of 2014 in Heshan, a supersite in the rural area of the Pearl River Delta (PRD region in China. Oxalic-acid-containing particles accounted for 2.5 and 2.7 % in total detected ambient particles in summer and winter, respectively. Oxalic acid was measured in particles classified as elemental carbon (EC, organic carbon (OC, elemental and organic carbon (ECOC, biomass burning (BB, heavy metal (HM, secondary (Sec, sodium-potassium (NaK, and dust. Oxalic acid was found predominantly mixing with sulfate and nitrate during the whole sampling period, likely due to aqueous-phase reactions. In summer, oxalic-acid-containing particle number and ozone concentration followed a very similar trend, which may reflect the significant contribution of photochemical reactions to oxalic acid formation. The HM particles were the most abundant oxalic acid particles in summer and the diurnal variations in peak area of iron and oxalic acid show opposite trends, which suggests a possible loss of oxalic acid through the photolysis of iron oxalato-complexes during the strong photochemical activity period. In wintertime, carbonaceous particles contained a substantial amount of oxalic acid as well as abundant carbon clusters and BB markers. The general existence of nitric acid in oxalic-acid-containing particles indicates an acidic environment during the formation process of oxalic acid. The peak areas of nitrate, sulfate and oxalic had similar temporal change in the carbonaceous type oxalic acid particles, and the organosulfate-containing oxalic acid particles correlated well with total oxalic acid particles during the haze episode, which suggests that the formation of oxalic acid is closely associated with the oxidation of organic precursors in the aqueous phase.

High-resolution sampling and analysis of ambient particulate matter in the Pearl River Delta region of southern China: source apportionment and health risk implications

Science.gov (United States)

Zhou, Shengzhen; Davy, Perry K.; Huang, Minjuan; Duan, Jingbo; Wang, Xuemei; Fan, Qi; Chang, Ming; Liu, Yiming; Chen, Weihua; Xie, Shanju; Ancelet, Travis; Trompetter, William J.

2018-02-01

Hazardous air pollutants, such as trace elements in particulate matter (PM), are known or highly suspected to cause detrimental effects on human health. To understand the sources and associated risks of PM to human health, hourly time-integrated major trace elements in size-segregated coarse (PM2.5-10) and fine (PM2.5) particulate matter were collected at the industrial city of Foshan in the Pearl River Delta region, China. Receptor modeling of the data set by positive matrix factorization (PMF) was used to identify six sources contributing to PM2.5 and PM10 concentrations at the site. Dominant sources included industrial coal combustion, secondary inorganic aerosol, motor vehicles and construction dust along with two intermittent sources (biomass combustion and marine aerosol). The biomass combustion source was found to be a significant contributor to peak PM2.5 episodes along with motor vehicles and industrial coal combustion. Conditional probability function (CPF) analysis was applied to estimate the source locations using the PMF-resolved source contribution coupled with the surface wind direction data. Health exposure risk of hazardous trace elements (Pb, As, Si, Cr, Mn and Ni) and source-specific values were estimated. The total hazard quotient (HQ) of PM2.5 was 2.09, higher than the acceptable limit (HQ = 1). The total carcinogenic risk (CR) was 3.37 × 10-3 for PM2.5, which was 3 times higher than the least stringent limit (1.0 × 10-4). Among the selected trace elements, As and Pb posed the highest non-carcinogenic and carcinogenic risks to human health, respectively. In addition, our results show that the industrial coal combustion source is the dominant non-carcinogenic and carcinogenic risk contributor, highlighting the need for stringent control of this source. This study provides new insight for policy makers to prioritize sources in air quality management and health risk reduction.

Non-polar organic compounds as PM2.5 source tracers: Investigation of their sources and degradation in the Pearl River Delta, China

Science.gov (United States)

Wang, Q.; Feng, Y.; Huang, X. H. H.; Griffith, S.; Zhang, T.; Zhang, Q.; Wu, D.; Yu, J.

2016-12-01

Nonpolar organic compounds (NPOCs) including alkanes, polycyclic aromatic hydrocarbons (PAHs), hopanes, steranes, and 1,3,5-triphenylbenzene, were quantified in PM2.5 samples at four sites in the Pearl River Delta (PRD) region, China over a two-year period from 2011 to 2012. The four sites include one industrial zone (Nanhai), one urban (Guangzhou), one urban outskirt (Dongguan) and one suburban (Nansha) locations. Some NPOCs are uniquely emitted from particular combustion sources, and thereby serving as convenient markers in source apportionment. Based on this multi-year and multi-site data set, spatial and seasonal variations, correlation analysis and ratio-ratio plots were used to investigate the source information and degradation of NPOC tracers. In summer, NPOCs showed distinct local emission characteristics, with urban sites having much higher concentrations than suburban site. In winter, regional transport was an important influence on NPOC levels, driving up concentrations at all sampling sites and diminishing an urban-suburban spatial gradient. The lighter NPOCs exhibited more prominent seasonal variations, suggesting their particle-phase abundance is more influenced by temperature, a critical factor in controlling the extent of semi-volatile organics partitioned into the aerosol phase. The heavier NPOCs, especially PAHs, showed negligible correlation among the four sites, suggesting more influence from local emissions. Ratio-ratio plots indicate photo-degradation and mixing of various sources for the NPOCs in the PRD. A positive matrix factorization (PMF) analysis of this large NPOC data set suggests that heavier NPOCs are more suitable source indicators than lighter NPOCs. Incorporating particle-phase light NPOC concentrations in PMF produces a separate factor, which primarily contains those light NPOCs and likely is not a source factor. Total NPOC concentrations predicted using Pankow partitioning theory were explored as PMF inputs, however, the PMF

Delta Vegetation and Land Use [ds292

Data.gov (United States)

California Natural Resource Agency — Vegetation and land use are mapped for the approximately 725,000 acres constituting the Legal Delta portion of the Sacramento and San Joaquin River Delta area....

Modern sedimentation and morphology of the subaqueous Mekong Delta, Southern Vietnam

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Unverricht, Daniel; Szczuciński, Witold; Stattegger, Karl; Jagodziński, Robert; Le, Xuan Thuyen; Kwong, Laval Liong Wee

2013-11-01

The Mekong River Delta is among the Asian mega-deltas and is influenced by various factors including tides (meso-tidal system), waves, coastal currents, monsoon-driven river discharge and human impact (agriculture, fishing, sand dredging, tourism). The present study aims to document the seafloor relief, sediment distribution and sediment accumulation rates to interpret modern sediment transport directions and main sedimentation processes in the subaqueous Mekong Delta. The major results of this investigation include the detection of two delta fronts 200 km apart, one at the mouth of the Bassac River (the biggest branch of the Mekong Delta) and the other around Cape Ca Mau (most south-western end of the Mekong Delta). Additionally, a large channel system runs in the subaqueous delta platform parallel to the shore and between the two fronts. The sediment accumulation rates vary greatly according to the location in the subaqueous delta and have reached up to 10 cm/yr for the last century. A cluster analysis of surface sediment samples revealed two different sediment types within the delta including a well-sorted sandy sediment and a poorly sorted, silty sediment. In addition, a third end member with medium to coarse sand characterised the distant parts of the delta at the transition to the open shelf. The increase of organic matter and carbonate content to the bottom set area and other sedimentary features such as shell fragments, foraminiferas and concretions of palaeo-soils that do not occur in delta sediments, supported grain size-based classification. Beginning in front of the Bassac River mouth, sedimentary pattern indicates clockwise sediment transport alongshore in the western direction to a broad topset area and the delta front around Cape Ca Mau. Our results clearly show the large lateral variability of the subaqueous Mekong Delta that is further complicated by strong monsoon-driven seasonality. River, tidal and wave forcing vary at local and seasonal scales

Assessment of River Habitat Quality in the Hai River Basin, Northern China

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Yuekui Ding

2015-09-01

Full Text Available We applied a river habitat quality (RHQ assessment method to the Hai River Basin (HRB; an important economic centre in China; to obtain baseline information for water quality improvement; river rehabilitation; and watershed management. The results of the assessment showed that the river habitat in the HRB is seriously degraded. Specifically; 42.41% of the sites; accounting for a river length of 3.31 × 104 km; were designated poor and bad. Habitat in the plain areas is seriously deteriorated; and nearly 50% of the sites; accounting for a river length of 1.65 × 104 km; had either poor or bad habitats. River habitat degradation was attributable to the limited width of the riparian zone (≤5 m; lower coverage of riparian vegetation (≤40%; artificial land use patterns (public and industrial land; frequent occurrence of farming on the river banks and high volumes of solid waste (nearly 10 m3; single flow channels; and rare aquatic plants (≤1 category. At the regional scale; intensive artificial land use types caused by urbanization had a significant impact on the RHQ in the HRB. RHQ was significantly and negatively correlated with farmland (r = 1.000; p < 0.01 and urban land (r = 0.998; p < 0.05; and was significantly and positively correlated with grassland and woodland (r = 1.000; p < 0.01. Intensive artificial land use; created through urbanization processes; has led to a loss of the riparian zone and its native vegetation; and has disrupted the lateral connectivity of the rivers. The degradation of the already essentially black rivers is exacerbated by poor longitudinal connectivity (index of connectivity is 2.08–16.56; caused by reservoirs and sluices. For river habitat rehabilitation to be successful; land use patterns need to be changed and reservoirs and sluices will have to be regulated.

Current situation of "Candidatus Liberibacter asiaticus" in Guangdong, P.R. China, where citrus huanglongbing was first described

Science.gov (United States)

Citrus Huanglongbing (HLB, yellow shoot disease) was observed in Guangdong Province, Peoples’ Republic of China in the late 1800s and is endemic there, particularly in the coastal Chaoshan and Pearl River Delta plains. Since the 1990s, the center of citrus production in Guangdong has gradually shif...

Delta Evolution at Røde Elv, Disko Island, Greenland

Science.gov (United States)

Kroon, A.; Arngrimson, J.; Bendixen, M.; Sigsgaard, C.

2017-12-01

Ice, snow and freezing temperatures have a large impact on coastal morphodynamics in Arctic polar environments. A recent warming of the Arctic climate induces many changes along the arctic shorelines. Sea-levels are rising due to thermal expansion and due to an increased fresh water flux from the glaciers and land ice masses. At the same time, the ice coverage of the coastal waters reduces and the open water periods in summer extend. There is a strong seasonal variation with open waters and active rivers in summer and ice-covered coastal waters and inactive rivers in winter. Coastal processes by waves and tides are thus limited to the summer and early fall. Besides, there is also a strong daily variation in fluvial discharges due to the daily variations in glacier melt with maximum melt in the afternoon and minimum values at night. At the same time, the actual flux of the river to the coastal bay is influenced by the tidal phase. Low tides will enhance the transport to the delta front, while high tides will create stagnant waters over the delta plain. The delta of the Røde Elv is located in southwestern Disko Island in west Greenland. It has a relatively small (ca. 101 km2) and partly glaciated drainage basin (ca. 20%) and its sediments consist of a mixture of basaltic sands and gravels. The Røde Elv delta is located at the end of a pro-glacial and fluvial valley at about 20 km from the glacier. The shores of the delta are reworked by waves, predominantly from southwestern, southern (largest fetch, over 50 km), and southeastern directions. The environment has a micro- to meso- tidal range with a spring tidal range of 2.7 m. The morphologic changes on the delta over the last decades clearly showed a seaward extension of the delta and a periodic shift in the location of the main delta channel. In this presentation, we focus on quantification of water discharges and suspended sediment fluxes to the Røde Elv delta in western Greenland, and on the morphological

Relationship of urinary arsenic metabolites to intake estimates in residents of the Red River Delta, Vietnam

Energy Technology Data Exchange (ETDEWEB)

Agusa, Tetsuro [Center for Marine Environmental Studies (CMES), Ehime University, Bunkyo-cho 2-5, Matsuyama 790-8577 (Japan); Department of Legal Medicine, Shimane University Faculty of Medicine, Enya 89-1, Izumo 693-8501 (Japan); Kunito, Takashi [Department of Environmental Sciences, Faculty of Science, Shinshu University, 3-1-1 Asahi, Matsumoto 390-8621 (Japan); Minh, Tu Binh [Center for Marine Environmental Studies (CMES), Ehime University, Bunkyo-cho 2-5, Matsuyama 790-8577 (Japan); Department of Biology and Chemistry (BCH), City University of Hong Kong, 83 Tat Chee Avenue, Kowloon Tong, Hong Kong (China); Pham Thi Kim Trang [Center for Environmental Technology and Sustainable Development (CETASD), Hanoi National University, 334 Nguyen Trai Street, Thanh Xuan, Hanoi (Viet Nam); Iwata, Hisato [Center for Marine Environmental Studies (CMES), Ehime University, Bunkyo-cho 2-5, Matsuyama 790-8577 (Japan); Pham Hung Viet [Center for Environmental Technology and Sustainable Development (CETASD), Hanoi National University, 334 Nguyen Trai Street, Thanh Xuan, Hanoi (Viet Nam); Tanabe, Shinsuke [Center for Marine Environmental Studies (CMES), Ehime University, Bunkyo-cho 2-5, Matsuyama 790-8577 (Japan)], E-mail: shinsuke@agr.ehime-u.ac.jp

2009-02-15

This study investigated the status of arsenic (As) exposure from groundwater and rice, and its methylation capacity in residents from the Red River Delta, Vietnam. Arsenic levels in groundwater ranged from <1.8 to 486 {mu}g/L. Remarkably, 86% of groundwater samples exceeded WHO drinking water guideline of 10 {mu}g/L. Also, estimated inorganic As intake from groundwater and rice were over Provisional Tolerable Weekly Intake (15 {mu}g/week/kg body wt.) by FAO/WHO for 92% of the residents examined. Inorganic As and its metabolite (monomethylarsonic acid and dimethylarsinic acid) concentrations in human urine were positively correlated with estimated inorganic As intake. These results suggest that residents in these areas are exposed to As through consumption of groundwater and rice, and potential health risk of As is of great concern for these people. Urinary concentration ratios of dimethylarsinic acid to monomethylarsonic acid in children were higher than those in adults, especially among men, indicating greater As methylation capacity in children. - Positive correlations between estimated arsenic intake and urinary inorganic arsenic and its metabolites were observed in human from the Red River Delta, Vietnam.

Relationship of urinary arsenic metabolites to intake estimates in residents of the Red River Delta, Vietnam

International Nuclear Information System (INIS)

Agusa, Tetsuro; Kunito, Takashi; Minh, Tu Binh; Pham Thi Kim Trang; Iwata, Hisato; Pham Hung Viet; Tanabe, Shinsuke

2009-01-01

This study investigated the status of arsenic (As) exposure from groundwater and rice, and its methylation capacity in residents from the Red River Delta, Vietnam. Arsenic levels in groundwater ranged from <1.8 to 486 μg/L. Remarkably, 86% of groundwater samples exceeded WHO drinking water guideline of 10 μg/L. Also, estimated inorganic As intake from groundwater and rice were over Provisional Tolerable Weekly Intake (15 μg/week/kg body wt.) by FAO/WHO for 92% of the residents examined. Inorganic As and its metabolite (monomethylarsonic acid and dimethylarsinic acid) concentrations in human urine were positively correlated with estimated inorganic As intake. These results suggest that residents in these areas are exposed to As through consumption of groundwater and rice, and potential health risk of As is of great concern for these people. Urinary concentration ratios of dimethylarsinic acid to monomethylarsonic acid in children were higher than those in adults, especially among men, indicating greater As methylation capacity in children. - Positive correlations between estimated arsenic intake and urinary inorganic arsenic and its metabolites were observed in human from the Red River Delta, Vietnam

The Central Role of the Mississippi River and its Delta in the Oceanography, Ecology and Economy of the Gulf of Mexico: A Synthesis

Science.gov (United States)

Kolker, A.; Chu, P. Y.; Taylor, C.; Roberts, B. J.; Renfro, A. A.; Peyronnin, N.; Fitzpatrick, C.

2017-12-01

While it has long been recognized that the Mississippi River is the largest source of freshwater, nutrients and sediments to the Gulf of Mexico, many questions remain unanswered about the impacts of the material on oceanography of the system. Here we report on the results of a regional synthesis study that examined how the Mississippi River and its delta influence the oceanography, ecology and the economy of the Gulf of Mexico. By employing a series of expert-opinion working groups, and using multi-dimensional numerical physical oceanographic models coupled to in-situ environmental data, this project is working to quantify how variability in discharge, meteorological forcings, and seasonal conditions influence the spatial distribution of the Mississippi River plume and its influence. Results collected to date indicate that the dimensions of the river plume are closely coupled to discharge, but in a non-linear fashion, that incorporates fluxes, flow distributions, offshore and meteorological forcings in the context of the local bathymetry. Ongoing research is using these human and numerical tools to help further elucidate the impacts of this river on the biogeochemistry of the region, and the distribution of key macrofauna. Further work by this team is examining how the delta's impacts on the ecology of the region, and the role that the delta plays as both a source of material for key offshore fauna, and a barrier to dispersal. This information is being used to help further the development of a research agenda for the northern Gulf of Mexico that will be useful through the mid-21st century.

Study on Remote Sensing Image Characteristics of Ecological Land: Case Study of Original Ecological Land in the Yellow River Delta

Science.gov (United States)

An, G. Q.

2018-04-01

Takes the Yellow River Delta as an example, this paper studies the characteristics of remote sensing imagery with dominant ecological functional land use types, compares the advantages and disadvantages of different image in interpreting ecological land use, and uses research results to analyse the changing trend of ecological land in the study area in the past 30 years. The main methods include multi-period, different sensor images and different seasonal spectral curves, vegetation index, GIS and data analysis methods. The results show that the main ecological land in the Yellow River Delta included coastal beaches, saline-alkaline lands, and water bodies. These lands have relatively distinct spectral and texture features. The spectral features along the beach show characteristics of absorption in the green band and reflection in the red band. This feature is less affected by the acquisition year, season, and sensor type. Saline-alkali land due to the influence of some saline-alkaline-tolerant plants such as alkali tent, Tamarix and other vegetation, the spectral characteristics have a certain seasonal changes, winter and spring NDVI index is less than the summer and autumn vegetation index. The spectral characteristics of a water body generally decrease rapidly with increasing wavelength, and the reflectance in the red band increases with increasing sediment concentration. In conclusion, according to the spectral characteristics and image texture features of the ecological land in the Yellow River Delta, the accuracy of image interpretation of such ecological land can be improved.

STUDY ON REMOTE SENSING IMAGE CHARACTERISTICS OF ECOLOGICAL LAND: CASE STUDY OF ORIGINAL ECOLOGICAL LAND IN THE YELLOW RIVER DELTA

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G. Q. An

2018-04-01

Full Text Available Takes the Yellow River Delta as an example, this paper studies the characteristics of remote sensing imagery with dominant ecological functional land use types, compares the advantages and disadvantages of different image in interpreting ecological land use, and uses research results to analyse the changing trend of ecological land in the study area in the past 30 years. The main methods include multi-period, different sensor images and different seasonal spectral curves, vegetation index, GIS and data analysis methods. The results show that the main ecological land in the Yellow River Delta included coastal beaches, saline-alkaline lands, and water bodies. These lands have relatively distinct spectral and texture features. The spectral features along the beach show characteristics of absorption in the green band and reflection in the red band. This feature is less affected by the acquisition year, season, and sensor type. Saline-alkali land due to the influence of some saline-alkaline-tolerant plants such as alkali tent, Tamarix and other vegetation, the spectral characteristics have a certain seasonal changes, winter and spring NDVI index is less than the summer and autumn vegetation index. The spectral characteristics of a water body generally decrease rapidly with increasing wavelength, and the reflectance in the red band increases with increasing sediment concentration. In conclusion, according to the spectral characteristics and image texture features of the ecological land in the Yellow River Delta, the accuracy of image interpretation of such ecological land can be improved.

Evaluation of ecological instream flow considering hydrological alterations in the Yellow River basin, China

Science.gov (United States)

Zhang, Qiang; Zhang, Zongjiao; Shi, Peijun; Singh, Vijay P.; Gu, Xihui

2018-01-01

The Yellow River is the second largest river in China and is the important source for water supply in the northwestern and northern China. It is often regarded as the mother river of China. Owing to climatic change and intensifying human activities, such as increasing withdrawal of water for meeting growing agricultural irrigation needs since 1986, the flow of Yellow River has decreased, with serious impacts on the ecological environment. Using multiple hydrological indicators and Flow Duration Curve (DFC)-based ecodeficit and ecosurplus, this study investigates the impact of hydrological alterations, such as the impact of water reservoirs or dams, on downstream ecological instream flow. Results indicate that: (1) due to the impoundment and hydrological regulations of water reservoirs, occurrence rates and magnitudes of high flow regimes have decreased and the decrease is also found in the magnitudes of low flow events. These changes tend to be more evident from the upper to the lower Yellow River basin; (2) human activities tend to enhance the instream flow variability, particularly after the 1980s;(3) the ecological environment in different parts of the Yellow River basin is under different degrees of ecological risk. In general, lower to higher ecological risk can be detected due to hydrological alterations from the upper to the lower Yellow River basin. This shows that conservation of ecological environment and river health is facing a serious challenge in the lower Yellow River basin; (4) ecological instream flow indices, such as ecodeficit and ecosurplus, and IHA32 hydrological indicators are in strong relationships, suggesting that ecodeficit and ecosurplus can be regarded as appropriate ecological indicators for developing measures for mitigating the adverse impact of human activities on the conservation of ecological environment in the Yellow River basin.

Shoreline dynamics of the active Yellow River delta since the implementation of Water-Sediment Regulation Scheme: A remote-sensing and statistics-based approach

Science.gov (United States)

Fan, Yaoshen; Chen, Shenliang; Zhao, Bo; Pan, Shunqi; Jiang, Chao; Ji, Hongyu

2018-01-01

The Active Yellow River (Huanghe) Delta (AYRD) is a complex landform in which rapid deposition takes place due to its geologic formation and evolution. Continuous monitoring of shoreline dynamics at high-temporal frequency is crucial for understanding the processes and the driving factors behind this rapidly changing coast. Great efforts have been devoted to map the changing shoreline of the Yellow River delta and explain such changes through remote sensing data. However, the temporal frequency of shoreline in the obtained datasets are generally not fine enough to reflect the detailed or subtly variable processes of shoreline retreat and advance. To overcome these limitations, we continuously monitored the dynamics of this shoreline using time series of Landsat data based on tidal-level calibration model and orthogonal-transect method. The Abrupt Change Value (ACV) results indicated that the retreat-advance patterns had a significant impact regardless of season or year. The Water-Sediment Regulation Scheme (WSRS) plays a dominant role in delivering river sediment discharge to the sea and has an impact on the annual average maximum ACV, especially at the mouth of the river. The positive relationship among the average ACV, runoff and sediment load are relatively obvious; however, we found that the Relative Exposure Index (REI) that measures wave energy was able to explain only approximately 20% of the variation in the data. Based on the abrupt change at the shoreline of the AYRD, river flow and time, we developed a binary regression model to calculate the critical sediment load and water discharge for maintaining the equilibrium of the active delta from 2002 to 2015. These values were approximately 0.48 × 108 t/yr and 144.37 × 108 m3/yr. If the current water and sediment proportions released from the Xiaolangdi Reservoir during the WSRS remain stable, the erosion-accretion patterns of the active delta will shift from rapid accretion to a dynamic balance.

Tracking historical lead pollution in the coastal area adjacent to the Yangtze River Estuary using lead isotopic compositions

International Nuclear Information System (INIS)

Hao Yunchao; Guo Zhigang; Yang Zuosheng; Fan, Dejiang; Fang Ming; Li Xiangdong

2008-01-01

The rapid economic development in the Yangtze River Delta (YRD), China in the last three decades has had a significant impact on the environment of the East China Sea (ECS). Lead isotopic compositions of a 210 Pb dated sediment core collected from the coastal ECS adjacent to the Yangtze River Estuary were analyzed to track the Pb pollution in the region. The baseline Pb concentration in the coastal ECS sediments before the industrialization in China was 32 μg g -1 , and the corresponding 206 Pb/ 207 Pb ratio was 1.195. The high-resolution profiles of Pb flux and 206 Pb/ 207 Pb ratios had close relationships with the economic development and the history of the use of leaded gasoline in China, and they were clearly different from those of most European countries and United States. - The combination of Pb concentration, sedimentary flux, Pb isotopic composition and 210 Pb dating in the coastal ECS sediments revealed the historical Pb pollution in China

VICIOUS CIRCULATION OF WATER DEFICIENCY AND WATER POLLUTION – “CANCER” OF THE RIVERS IN THE NORTH OF CHINA.

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Yang Liankang

2005-05-01

Full Text Available The North of China belongs to the basin of the Tarim River ,the Heihe River , the Yellow River , the Huaihe River ,the Haihe River ,the Liaohe River , the Heilongjiang River and other shorter rivers and other indraft areas. The total area of all river basin is about 3,200,000 sq. km., exceeds 3/5 of area of land of 13 provinces , municipalities and autonomous regions of the North of China (5, 220,000 sq. km. .Follow the growth of the economy and the population, lacking of water in the rivers of the northern China is serious,. Since the sixties and seventies of previous century, the blanking has taken place successively in numerous rivers, brought serious influence on the development of the economic, made the society to shake. Afterwards, through certain effort, although the blanking phenomenon is alleviated for the past several years, but the water quality of manyrivers has sharply worsened and was dropped to V, bad V grade in the numerous sections, fromthe situation that the water quality in a great part sections in the main stream was still rather good for past more than 20 years ago. It has become the first killer, influencing the life of river.Therefore, we must summarize the experiences on that the rivers of the northern China, especially the most influential Yellow River, have gone from blanking to resuming flow, we also must control the pollution and proportionate the development of the society and theeconomic, with the water yield and the water quality. These affair have already become task of top priority!

Status of POPs accumulation in the Yellow River Delta: From distribution to risk assessment

International Nuclear Information System (INIS)

Li, Jing; Chen, Chunli; Li, Fadong

2016-01-01

The Yellow River Delta (YRD) is a large region of China with complex pollution sources and a long history of environmental deterioration. Despite this, relatively little data exists on the status of important contaminants of concern in this region. Here, we review the literature on the status of key persistent organic pollutants (POPs) of concern including organochlorine pesticides (OCPs), polycyclic aromatic hydrocarbons (PAHs), and polychlorinated biphenyls (PCBs) in the YRD. Sources, source identification methods, and spatial distribution patterns are presented. Additionally, POPs contamination levels reported in the literature were evaluated against popular regulatory limits worldwide to form a basis for overall environmental health. Our review determined that OCPs in the YRD originated mainly from current pesticide use and past agricultural pesticide application. Sources of PAHs included petrochemical inputs, coal fired plants, and wood combustion. PCB levels were impacted by the petrochemical industry as well as waste disposal of PCB containing equipment. OCPs exhibited a spatial distribution pattern that increased along the urban–rural gradient, while the opposite was seen for PAHs and PCBs. Comparisons of POPs contamination levels in the YRD with popular regulatory limits suggest that the extent of PCB contamination all mediums (sediment, soil, water, and biota) exceeded that of PAHs and OCPs. Overall pollution levels in the YRD seem to be in control; however, levels from heavily polluted point sources raise numerous concerns about the ecological health of the region and require more attention from regulatory authorities. - Highlights: •Previous usage of POPs, regulatory limits and source identification methods used in China and abroad were summarized. •Environment occurrence, source and risk of OCPs, PCBs and PAHs are reviewed. •Both OCPs and PAHs residue are relatively low, but PCBs residue is at a higher degree. •Spatial pattern of OCPs showed

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

Science.gov (United States)

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.

Nonpolar organic compounds as PM2.5 source tracers: Investigation of their sources and degradation in the Pearl River Delta, China

Science.gov (United States)

Wang, Qiongqiong; Feng, Yongming; Huang, X. H. Hilda; Griffith, Stephen M.; Zhang, Ting; Zhang, Qingyan; Wu, Dui; Yu, Jian Zhen

2016-10-01

A group of nonpolar organic compounds (NPOCs) in five compound classes including alkanes, polycyclic aromatic hydrocarbons (PAHs), hopanes, steranes, and 1,3,5-triphenylbenzene were quantified in samples of particulate matter of aerodynamic diameter less than 2.5 μm collected at four sites in the Pearl River Delta (PRD) region, China, over a 2 year period from 2011 to 2012. The four sites include industrial (Nanhai), urban (Guangzhou), urban outskirt (Dongguan), and suburban (Nansha) locations. Some NPOCs are uniquely emitted from particular combustion sources and thereby serving as markers in source apportionment. Based on this multiyear and multisite NPOC data set, spatial and seasonal variations, correlation analysis, and ratio-ratio plots were used to investigate the source information and degradation of NPOC tracers. In summer, NPOCs showed distinct local emission characteristics, with urban sites having much higher concentrations than suburban sites. In winter, regional transport was an important influence on NPOC levels, driving up concentrations at all sampling sites and diminishing an urban-suburban spatial gradient. The lighter NPOCs exhibited more prominent seasonal variations. Such spatiotemporal features suggest that their particle-phase abundance is more influenced by temperature, which is a critical factor in controlling the extent of semivolatile organics partitioned into the aerosol phase. The heavier NPOCs, especially PAHs, showed negligible correlation among the four sites, suggesting more influence from local emissions. Ratio-ratio plots indicate photodegradation and mixing of various sources for the NPOCs in the PRD. A positive matrix factorization (PMF) analysis of this large NPOC data set suggests that heavier NPOCs are more suitable source indicators than lighter NPOCs. Incorporating particle-phase light NPOC concentrations in PMF produces a separate factor, which primarily contains those light NPOCs and likely is not a source factor. Total

Drones on the delta | CRDI - Centre de recherches pour le ...

International Development Research Centre (IDRC) Digital Library (Canada)

25 nov. 2016 ... Waves wash ashore at Fuvemeh, a town in Ghana's Volta River delta that's threatened by coastal erosion and flooding. Brian Owens, Canadian Geographic. Ghana's Volta River delta is an area vulnerable to climate change, with rising seas and increasingly powerful storms driving flooding and erosion, ...

DELTAS: A new Global Delta Sustainability Initiative (Invited)

Science.gov (United States)

Foufoula-Georgiou, E.

2013-12-01

Deltas are economic and environmental hotspots, food baskets for many nations, home to a large part of the world population, and hosts of exceptional biodiversity and rich ecosystems. Deltas, being at the land-water interface, are international, regional, and local transport hubs, thus providing the basis for intense economic activities. Yet, deltas are deteriorating at an alarming rate as 'victims' of human actions (e.g. water and sediment reduction due to upstream basin development), climatic impacts (e.g. sea level rise and flooding from rivers and intense tropical storms), and local exploration (e.g. sand or aggregates, groundwater and hydrocarbon extraction). Although many efforts exist on individual deltas around the world, a comprehensive global delta sustainability initiative that promotes awareness, science integration, data and knowledge sharing, and development of decision support tools for an effective dialogue between scientists, managers and policy makers is lacking. Recently, the international scientific community proposed to establish the International Year of Deltas (IYD) to serve as the beginning of such a Global Delta Sustainability Initiative. The IYD was proposed as a year to: (1) increase awareness and attention to the value and vulnerability of deltas worldwide; (2) promote and enhance international and regional cooperation at the scientific, policy, and stakeholder level; and (3) serve as a launching pad for a 10-year committed effort to understand deltas as complex socio-ecological systems and ensure preparedness in protecting and restoring them in a rapidly changing environment. In this talk, the vision for such an international coordinated effort on delta sustainability will be presented as developed by a large number of international experts and recently funded through the Belmont Forum International Opportunities Fund. Participating countries include: U.S., France, Germany, U.K., India, Japan, Netherlands, Norway, Brazil, Bangladesh

Ecosystem Services and Related Sustainable Management of River Oases along the Tarim River in Northwest China

Science.gov (United States)

Disse, M.; Keilholz, P.; Rumbaur, C.; Thevs, N.

2011-12-01

Within the Taklimakan Desert of Northwestern China, an area renowned for its extreme climate and vulnerable ecosystems, lies one of the largest inland rivers in the world, the Tarim River. Because the Tarim River is located in a remote area from the oceans, rainfall is extremely rare (less than 50 mm per year) but potential evaporation is high (3000 mm). Thus, the major source of water discharge comes from snowmelt and glacier-melt in the mountains. Though the water discharge into the Tarim River has experienced an increase over the past ten years, global climate change forecasts predict this water supply to decline within the century. The Tarim River is the major source of water in Northwestern China, and has become the hub of many economic activities related to agriculture and urban life. Over the past 50 years increased activity in the area has led to a severe decline in river flow. Both human and natural ecosystems have been impacted by water diversions. Since rainfall is rare, the majority of vegetation in this area depends solely on groundwater for survival, and plants are experiencing stress caused by decreasing groundwater levels. Recently nearby cities have experienced severe dust storms caused by the shrinking of the vegetative region along the river. SuMaRiO (Sustainable Management of River Oases) is a bundle project between Germany and China working to contribute to a sustainable land management which explicitly takes into account ecosystem functions (ESF) and ecosystem services (ESS). In a transdisciplinary research process, SuMaRiO will identify realizable management strategies, considering social, economic and ecological criteria. SuMaRiO is developing tools to work with Chinese decision makers to implement sustainable land management strategies. In addition, research is being conducted to estimate climate change impacts, floodplain biodiversity, and water runoff characteristics. The overarching goal of SuMaRiO is to support oasis management along

[Seasonal variation patterns of NH4(+) -N/NO3(-) -N ratio and delta 15 NH4(+) value in rainwater in Yangtze River Delta].

Science.gov (United States)

Xie, Ying-Xin; Zhang, Shu-Li; Zhao, Xu; Xiong, Zheng-Qin; Xing, Guang-Xi

2008-09-01

By using a customized manual rainwater sampler made of polyvinyl chloride plastic, the molar ratio of NH4(+) -N/NO3(-) -N and the natural 15N abundance of NH4(+) (delta 15 NH4(+) in rainwater was monitored all year round from June 2003 to July 2005 at three observation sites (Changshu, Nanjing, and Hangzhou) in the Yangtze River Delta. The results indicated that at the three sites, the NH4(+) -N/NO3(-) -N ratio and the delta 15 NH4(+) value in rainwater had the similar seasonal variation trend, being more obvious in Changshu (rural monitoring type) site than in Nanjing (urban monitoring type) and Hangzhou (urban-rural monitoring type) sites. The NH4(+) -N/NO3(-) -N ratio peaked from early June to early August, declined gradually afterwards, and reached the bottom in winter; while the delta 15 NH4(+) value was negative from late June to mid-August, turned positive from late August to mid or late November, became negative again when winter dominated from December to March, but turned positive again in next May and negative again in next July. These seasonal variation patterns of NH4(+) -N/NO3(-) -N ratio and delta 15 NH4(+) value were found in relation to the application of chemical nitrogen fertilizers during different crop growth periods, and also, the alternation of seasons and the NH3 volatilization from other NH3 emission sources (including excrements of human and animals, nitrogen- polluted water bodies, and organic nitrogen sources, etc.), which could be taken as an indicator of defining the sources and form composition of NH4(+) in atmospheric wet deposition and the intensity of various terrestrial NH3 emission sources.

Geochemical Dataset of the Rhone River Delta (Lake Geneva) Sediments - Disentangling Human Impacts from Climate Change

Science.gov (United States)

Silva, T. A.; Girardclos, S.; Loizeau, J. L.

2016-12-01

Lake sediment records are often the most complete continental archives. In the last 200 years, in addition to climatic variability, humans have strongly impacted lake watersheds around the world. During the 20th century the Rhone River and its watershed upstream Lake Geneva (Switzerland/France) have been subject to river channelization, dam construction, water flow regulation, water and sediment abstraction as well as various land use changes. Under the scope of the SEDFATE project (Swiss National Science Foundation nº147689) we address human and climatic impact on the sediment transfer from the Rhone River watershed to Lake Geneva. Nineteen short sediment cores were collected in the Rhone River delta area in May 2014. Cores have been scanned with MSCL and XRF, sub-sampled every 1cm and 8 cores were dated by radiometric methods (137Cs and 210Pb). Photographs taken right after core opening were used for lithological description and in addition to MSCL data were used to correlate cores. Core dating shows that mass accumulation rates decreased in the 1964-1986 interval and then increased again in the interval between 1986-2014. XRF elements and ratios, known to indicate detrital sources (Al, Al/Si, Fe, K, Mn, Rb, Si, Ti, Ti/Ca), show that clastic input diminished from 1964 to 1986 and re-increased to the present. Other elemental (Zr/Rb, Zr/K, Si/Ti) and geophysical data (magnetic susceptibility) combined with lithology identify density flow deposits vs hemipelagic sedimentation. Changes in frequency of these event deposits indicate changes in the sedimentation patterns in the Rhone River sublacustrine delta during the last century. From these results we hypothesize that a significant sediment amount was abstracted from the system after the major dam constructions in the 1950's and that, since the 1990's, a contrary signal is due to increased sediment loads that follows glacial melting due to global warming.

Suitability Evaluation of River Bank Filtration along the Second Songhua River, China

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Lixue Wang

2016-04-01

Full Text Available The Second Songhua River is the biggest river system in Jilin Province, China. In recent years, the rapid economic development in this area has increased the prominence of water resources and water-related environmental problems; these include surface water pollution and the overexploitation of groundwater resources. Bank infiltration on the floodplains of the Second Songhua River is an important process of groundwater-surface water exchange under exploitation conditions. Understanding this process can help in the development of water resource management plans and strategies for the region. In this research, a multi-criteria evaluation index system was developed with which to evaluate the suitability of bank filtration along the Second Songhua River. The system was comprised of main suitability indexes for water quantity, water quality, the interaction intensity between surface water and groundwater, and the exploitation condition of groundwater resources. The index system was integrated into GIS (Geographic Information System to complete the evaluation of the various indicators. According to the weighted sum of each index, the suitability of river bank filtration (RBF in the study area was divided into five grades. Although the evaluation index system and evaluation method are applicable only to the Second Songhua River basin, the underlying principle and techniques it embodies can be applied elsewhere. For future generalization of the evaluation index system, the specific evaluation index and its scoring criteria should be modified appropriately based on local conditions.

Identification of anthropogenic and natural inputs of sulfate and chloride into the karstic ground water of Guiyang, SW China: combined delta37Cl and delta34S approach.

Science.gov (United States)

Liu, Cong-Qiang; Lang, Yun-Chao; Satake, Hiroshi; Wu, Jiahong; Li, Si-Liang

2008-08-01

Because of active exchange between surface and groundwater of a karstic hydrological system, the groundwater of Guiyang, the capital city of Guizhou Province, southwest China, has been seriously polluted by anthropogenic inputs of NO3-, SO4(2-), Cl-, and Na+. In this work, delta37Cl of chloride and delta34S variations of sulfate in the karstic surface/groundwater system were studied, with a main focus to identify contaminant sources, including their origins. The surface, ground, rain, and sewage water studied showed variable delta37Cl and delta34S values, in the range of -4.1 to +2.0 per thousand, and -20.4 to +20.9 per thousand for delta37Cl and delta34S (SO4(2-)), respectively. The rainwater samples yielded the lowest delta37Cl values among those observed to date for aerosols and rainwater. Chloride in the Guiyang area rain waters emanated from anthropogenic sources rather than being of marine origin, probably derived from HCl (g) emitted by coal combustion. By plotting 1/SO4(2-) vs delta34S and 1/Cl- vs delta37Cl, respectively, we were able to identify some clusters of data, which were assigned as atmospheric deposition (acid rain component), discharge from municipal sewage, paleo-brine components in clastic sedimentary rocks, dissolution of gypsum mainly in dolomite, oxidation of sulfide minerals in coal-containing clastic rocks, and possibly degradation of chlorine-containing organic matter. We conclude that human activities give a significant input of sulfate and chloride ions, as well as other contaminants, into the studied groundwater system through enhanced atmospheric deposition and municipal sewage, and that multiple isotopic tracers constitute a powerful tool to ascertain geochemical characteristics and origin of complex contaminants in groundwater.

Understanding NOx emission trends in China based on OMI observations

Science.gov (United States)

Wang, Y.; Ga, D.; Smeltzer, C. D.; Yi, R.; Liu, Z.

2012-12-01

We analyze OMI observations of NO2 columns over China from 2005 to 2010. Simulations using a regional 3-D chemical transport model (REAM) are used to derive the top-down anthropogenic NOx emissions. The Kendall method is then applied to derive the emission trend. The emission trend is affected by the economic slowdown in 2009. After removing the effect of one year abnormal data, the overall emission trend is 4.35±1.42% per year, which is slower than the linear-regression trend of 5.8-10.8% per year reported for previous years. We find large regional, seasonal, and urban-rural variations in emission trend. The annual emission trends of Northeast China, Central China Plain, Yangtze River Delta and Pearl River Delta are 44.98±1.39%, 5.24±1.63%, 3.31±1.02% and -4.02±1.87%, respectively. The annual emission trends of four megacities, Beijing, Shanghai, Guangzhou and Shenzhen are 0.7±0.27%, -0.75±0.31%, -4.08±1.21% and -6.22±2.85%,, considerably lower than the regional averages. These results appear to suggest that a number of factors, including migration of high-emission industries, vehicle emission regulations, emission control measures of thermal power plants, increased hydro-power usage, have reduced or reversed the increasing trend of NOx emissions in more economically developed megacities and southern coastal regions.

Ground-level ozone pollution and its health impacts in China

Science.gov (United States)

Liu, Huan; Liu, Shuai; Xue, Boru; Lv, Zhaofeng; Meng, Zhihang; Yang, Xiaofan; Xue, Tao; Yu, Qiao; He, Kebin

2018-01-01

In recent years, ground-level ozone pollution in China has become an increasingly prominent problem. This study simulated and analyzed spatiotemporal distribution of ozone and exposure level by the Weather Research and Forecasting (WRF)-Community Multiscale Air Quality (CMAQ) models and monitoring data from 1516 national air quality monitoring stations in China during 2015. The simulation results show that the Sichuan Basin, Shandong, Shanxi, Henan, Anhui, Qinghai-Tibetan Plateau, Yangtze River Delta (YRD), Pearl River Delta (PRD) and Beijing-Tianjin-Hebei (BTH) region had relatively high average annual concentrations of ozone. The regions with more than 10% nonattainment days of 160 μg/m3 (daily maximum 8-h) are mainly concentrated in BTH, Shandong Peninsula and YRD, where large seasonal variations were also found. Exposure levels were calculated based on population data and simulated ozone concentrations. The cumulative population exposed to daily maximum 8-h concentration greater than or equal to 100 μg/m3 was 816.04 million, 61.17% of the total. Three methods were used to estimate the mortality of chronic obstructive pulmonary disease (COPD) attributable to ozone. A comparative study using different exposure concentrations and threshold concentrations found large variations among these methods, although they were all peer-reviewed methods. The estimated mortality of COPD caused by ozone in China in 2015 ranged from 55341 to 80280, which mainly distributed in Beijing, Shandong, Henan, Hubei and Sichuan Province, the YRD and PRD region.

Impact of water diversion on the hydrogeochemical characterization of surface water and groundwater in the Yellow River Delta

International Nuclear Information System (INIS)

Liu, Qiang; Li, Fadong; Zhang, Qiuying; Li, Jing; Zhang, Yan; Tu, Chun; Ouyang, Zhu

2014-01-01

Highlights: • We assess the response of different ecosystems to the water diversion. • We characterized the interaction between surface water and groundwater. • We use the Piper and HFE-D to illustrate the salinization process. - Abstract: The Yellow River Delta is undergoing severe ecosystem degradation through salinization caused mainly by seawater intrusion. The Yellow River diversion project, in operation since 2008, aims to mitigate a projected ecosystem disaster. We conducted field investigations across three ecosystems (Farmland, Wetland and Coast) in the delta to assess the effectiveness of the annual water pulse and determine the relationships between surface water and groundwater. The chemical characteristics of the groundwater in Farmland exclude the possibility of seawater intrusion. The Wetland is vulnerable to pollution by groundwater discharge from Farmland and to secondary salinization caused by rising water tables. The salinity values of groundwater at Coast sites likely reflect the presence of seawater trapped in the clay sediments, a premise corroborated through measurements of groundwater levels, stable isotopes and major ion signatures. Our δD–δ 18 O two-dimensional graphic plot demonstrated that groundwaters of Farmland and Wetland changed toward more depleted isotopic compositions following water diversion, but this was not the case in the Coast sites, where the water table varied little year-round. A hydrochemical facies evolution diagram (HFE-D) demonstrated that freshening is taking place in the largest portions of the aquifers and that, without sustained water diversion recharge, these underground water bodies may switch from freshening to salinization on a seasonal time scale. Thus, the qualities of waters in coastal aquifers in the Yellow River Delta are substantially influenced by the process of ecological water diversion, and also by land use practices and by the lithological properties of the drainage landscape

Recent Advances in Understanding Flow Dynamics and Transport of Water-Quality Constituents in the Sacramento–San Joaquin River Delta

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David H. Schoellhamer

2016-12-01

Full Text Available doi: https://doi.org/10.15447/sfews.2016v14iss4art1This paper, part of the collection of research comprising the State of Bay–Delta Science 2016, describes advances during the past decade in understanding flow dynamics and how water-quality constituents move within California’s Sacramento–San Joaquin River Delta (Delta. Water-quality constituents include salinity, heat, oxygen, nutrients, contaminants, organic particles, and inorganic particles. These constituents are affected by water diversions and other human manipulations of flow, and they greatly affect the quantity and quality of benthic, pelagic, and intertidal habitat in the Delta. The Pacific Ocean, the Central Valley watershed, human intervention, the atmosphere, and internal biogeochemical processes are all drivers of flow and transport in the Delta. These drivers provide a conceptual framework for presenting recent findings. The tremendous expansion of acoustic and optical instruments deployed in the Delta over the past decade has greatly improved our understanding of how tidal variability affects flow and transport. Sediment is increasingly viewed as a diminishing resource needed to sustain pelagic habitat and tidal marsh, especially as sea level rises. Connections among the watershed, Delta, and San Francisco Bay that have been quantified recently highlight that a landscape view of this system is needed, rather than consideration of each region in isolation. We discuss interactions of multiple drivers and information gaps.

Significant concentration changes of chemical components of PM1 in the Yangtze River Delta area of China and the implications for the formation mechanism of heavy haze-fog pollution.

Science.gov (United States)

Zhang, Y W; Zhang, X Y; Zhang, Y M; Shen, X J; Sun, J Y; Ma, Q L; Yu, X M; Zhu, J L; Zhang, L; Che, H C

2015-12-15

Since the winter season of 2013, a number of persistent haze-fog events have occurred in central-eastern China. Continuous measurements of the chemical and physical properties of PM1 at a regional background station in the Yangtze River Delta area of China from 16 Nov. to 18 Dec., 2013 revealed several haze-fog events, among which a heavy haze-fog event occurred between 6 Dec. and 8 Dec. The mean concentration of PM1 was 212μgm(-3) in the heavy haze-fog period, which was about 10 times higher than on clean days and featured a peak mass concentration that reached 298μgm(-3). Organics were the largest contributor to the dramatic rise of PM1 on heavy haze-fog days (average mass concentration of 86μgm(-3)), followed by nitrate (58μgm(-3)), sulfate (35μgm(-3)), ammonium (29μgm(-3)), and chloride (4.0μgm(-3)). Nitrate exhibited the largest increase (~20 factors), associated with a significant increase in NOx. This was mainly attributable to increased coal combustion emissions, relative to motor vehicle emissions, and was caused by short-distance pollutant transport within surrounding areas. Low-volatility oxidized organic aerosols (OA) (LV-OOA) and biomass-burning OA (BBOA) also increased sharply on heavy haze-fog days, exhibiting an enhanced oxidation capacity of the atmosphere and increased emissions from biomass burning. The strengthening of the oxidation capacity during the heavy pollution episode, along with lower solar radiation, was probably due to increased biomass burning, which were important precursors of O3. The prevailing meteorological conditions, including low wind and high relative humidity, and short distance transported gaseous and particulate matter surrounding of the sampling site, coincided with the increased pollutant concentrations mainly from biomass-burning mentioned above to cause the persistent haze-fog event in the YRD area. Copyright © 2015. Published by Elsevier B.V.

Source Apportionment of Volatile Organic Compounds in an Urban Environment at the Yangtze River Delta, China.

Science.gov (United States)

An, Junlin; Wang, Junxiu; Zhang, Yuxin; Zhu, Bin

2017-04-01

Volatile organic compounds (VOCs) were collected continuously during June-August 2013 and December 2013-February 2014 at an urban site in Nanjing in the Yangtze River Delta. The positive matrix factorization receptor model was used to analyse the sources of VOCs in different seasons. Eight and seven sources were identified in summer and winter, respectively. In summer and winter, the dominant sources of VOCs were vehicular emissions, liquefied petroleum gas/natural gas (LPG/NG) usage, solvent usage, biomass/biofuel burning, and industrial production. In summer, vehicular emissions made the most significant contribution to ambient VOCs (38%), followed by LPG/NG usage (20%), solvent usage (19%), biomass/biofuel burning (13%), and industrial production (10%). In winter, LPG/NG usage accounted for 36% of ambient VOCs, whereas vehicular emissions, biomass/biofuel burning, industrial production and solvent usage contributed 30, 18, 9, and 6%, respectively. The contribution of LPG/NG usage in winter was approximately four times that in summer, whereas the contribution from biomass/biofuel burning in winter was more than twice that in summer. The sources related to vehicular emissions and LPG/NG usages were important. Using conditional probability function analysis, the VOC sources were mainly associated with easterly, northeasterly and southeasterly directions, pointing towards the major expressway and industrial area. Using the propylene-equivalent method, paint and varnish (23%) was the highest source of VOCs in summer and biomass/biofuel burning (36%) in winter. Using the ozone formation potential method, the most important source was biomass/biofuel burning (32% in summer and 47% in winter). The result suggests that the biomass/biofuel burning and paint and varnish play important roles in controlling ozone chemical formation in Nanjing.

Preliminary Study on Effect of Herbicides on Alfalfa Yield and Weed Community Characteristics in Yellow River Delta, China

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WANG Guo-liang

2016-05-01

Full Text Available Alfalfa(Medicago sativa is one of important legume forages worldwide. However, weed is the main factor limiting alfalfa production. Biomass quality and yield and stability of dry matter production during cultivation are directly associated with the interference of weeds which compete with alfalfa for water, light and nutrients. The use of herbicides is a good alternative for weed control. In order to control weed in alfalfa field with suitable herbicide in Yellow River delta, the effect of four herbicides(imazethapyr, quizalofop-p-ethyl, haloxyfop-r-methyl and oxyfluorfen with different concentration on afalfal yield and weed community characteristics were studied. The results showed that both imazethapyr and haloxyfop-r-methyl treatments could increase alfalfa yield, and the best herbicide application concentration was imazethapyr with 2 000 mL·hm-2 and haloxyfop-r-methyl with 700 mL·hm-2, but oxyfluorfen treatment would limit alfalfa growth significantly. Weed species numbers in the treatments of imazethapyr, quizalofop-p-ethyl and oxyfluorfen decreased significantly. Digitariasanguinalis, Portulacaoleracea and Echinochloacrusgalli were more difficult to control from specie important value in all treatments. Species diversity index decreased with higher herbicide concentration in all treatments. From this study, herbicide imazethapyr with 2 000 mL·hm-2 application concentration was the best weed control method, and the second one was haloxyfop-r-methyl with 700 mL·hm-2 application concentration.

Highly time-resolved urban aerosol characteristics during springtime in Yangtze River Delta, China: insights from soot particle aerosol mass spectrometry

Science.gov (United States)

Wang, Junfeng; Ge, Xinlei; Chen, Yanfang; Shen, Yafei; Zhang, Qi; Sun, Yele; Xu, Jianzhong; Ge, Shun; Yu, Huan; Chen, Mindong

2016-07-01

In this work, the Aerodyne soot particle - aerosol mass spectrometer (SP-AMS) was deployed for the first time during the spring of 2015 in urban Nanjing, a megacity in the Yangtze River Delta (YRD) of China, for online characterization of the submicron aerosols (PM1). The SP-AMS enables real-time and fast quantification of refractory black carbon (rBC) simultaneously with other non-refractory species (ammonium, sulfate, nitrate, chloride, and organics). The average PM1 concentration was found to be 28.2 µg m-3, with organics (45 %) as the most abundant component, following by sulfate (19.3 %), nitrate (13.6 %), ammonium (11.1 %), rBC (9.7 %), and chloride (1.3 %). These PM1 species together can reconstruct ˜ 44 % of the light extinction during this campaign based on the IMPROVE method. Chemically resolved mass-based size distributions revealed that small particles especially ultrafine ones (cooking-related OA (COA), semi-volatile oxygenated OA (SV-OOA), and low-volatility oxygenated OA (LV-OOA). Overall, secondary organic aerosol (SOA, equal to the sum of SV-OOA and LV-OOA) dominated the total OA mass (55.5 %), but primary organic aerosol (POA, equal to the sum of HOA and COA) can outweigh SOA in the early morning and evening due to enhanced human activities. High OA concentrations were often associated with high mass fractions of POA and rBC, indicating the important role of anthropogenic emissions during heavy pollution events. The diurnal cycles of nitrate, chloride, and SV-OOA both showed good anti-correlations with air temperatures, suggesting their variations were likely driven by thermodynamic equilibria and gas-to-particle partitioning. On the other hand, in contrast to other species, sulfate, and LV-OOA concentrations increased in the afternoon, and showed no positive correlations with relative humidity (RH), likely indicating the contribution from photochemical oxidation is dominant over that of aqueous-phase processing for their formations. The

ENVIRONMENTAL MECHANISM OF REGIONAL LONGEVITY IN CHINA

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Wuyi Wang

2015-01-01

Full Text Available The integrated study on environment of typical China’s longevity areas was conducted by using comprehensive methods of health geography. It was found that Chinese longevity areas mainly located in the south China and clustered in Sichuan-Chongqing, Central plain and Southeast region, the Yangtze River Delta and Pearl River Delta; in which drinking water was of weakly alkaline, Se, Fe, K content was moderate, higher content of Ca, Co, Mn, and low Cr, Cd, Pb; the concentration of trace elements benefit for health in soils and food staples was higher; hair of centenarians had higher Li, Mg, Mn, Ca, Zn content, lower concentration in Cd, Cr, Cu, Ni; healthy centenarians were also benefited from a favorable social environment factors, such as physiological health, psychological state, light meals and higher proportion of vegetables. The study was the first time to reveal quantitatively the relationship between longevity and the natural and human environment, and provided a scientific basis for the promotion of development of China’s longevity area, to achieve the construction of ecological civilization

Late quaternary evolution of the Orinoco Delta, Venezuela

Science.gov (United States)

Warne, A.G.; Guevara, E.H.; Aslan, A.

2002-01-01

The modern Orinoco Delta is the latest of a series of stacked deltas that have infilled the Eastern Venezuelan Basin (EVB) since the Oligocene. During the late Pleistocene sea-level lowstand (20,000 to 16,000 yrs BP), bedrock control points at the position of the present delta apex prevented the river channel from incising as deeply as many other major river systems. Shallow seismic data indicate that the late Pleistocene Orinoco incised into the present continental shelf, where it formed a braided-river complex that transported sediment to a series of shelf-edge deltas. As sea level rose from 16,000 to 9,500 yrs BP, the Orinoco shoreline shifted rapidly landward, causing shallow-marine waves and currents to form a widespread transgressive sand unit. Decelerating sea-level rise and a warmer, wetter climate during the early Holocene (9,500 to 6,000 yrs BP) induced delta development within the relatively quiet-water environment of the EVB embayment. Sea level approached its present stand in the middle Holocene (6,000 to 3,000 yrs BP), and the Orinoco coast prograded, broadening the delta plain and infilling the EVB embayment. Significant quantities of Amazon sediment began to be transported to the Orinoco coast by littoral currents. Continued progradation in the late Holocene caused the constriction at Boca de Serpientes to alter nearshore and shelf hydrodynamics and subdivide the submarine delta into two distinct areas: the Atlantic shelf and the Gulf of Paria. The increased influence of littoral currents along the coast promoted mudcape development. Because most of the water and sediment were transported across the delta plain through the Rio Grande distributary in the southern delta, much of the central and northwestern delta plain became sediment starved, promoting widespread accumulation of peat deposits. Human impacts on the delta are mostly associated with the Volca??n Dam on Can??o Manamo. However, human activities have had relatively little effect on the

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

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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

Peat or no peat: Why do the Rajang and Mahakam Deltas differ?

Energy Technology Data Exchange (ETDEWEB)

Gastaldo, Robert A. [Department of Geology, Colby College, 5807 Mayflower Hill Drive, Waterville, ME 04901 (United States)

2010-08-01

Coastal and deltaic Holocene peat accumulations around the equatorial island of Borneo, Southeast Asia, have served as models for economic coal-bearing sequences in the stratigraphic record. Although climatic conditions, vegetational communities, and sedimentary regimes are comparable, peat accumulations are not found on both the western and eastern sides of the island. The Rajang River delta and coastal plain, Sarawak, East Malaysia, are covered in areally extensive, thick peat deposits that have attained at least a thickness of > 13 m in ombrogenous peat domes (Marudi, Baram River). Peat-swamp biomass began to accumulate over Pleistocene podzols when sea level stabilized {proportional_to} 7.5 ka and delta progradation was initiated. The Mahakam River delta and coastal plain, East Kalimantan, Indonesia, also began progradation at this time, but there is no evidence in any part of the coastal region for peat accumulation. Rather, poorly developed organic-rich gleysols occur throughout the delta plain. Both the Rajang River and Mahakam River deltas are tidally influenced, fine-grained systems, with a sediment provenance in the Central Massif. Sediment transported through the Rajang River delta differs in that as much as 60% of the clay minerals deposited in the system are mixed layer (I/S) and expandable (K/E) clays that act to restrict pore water flow in the tidal and overbank deposits that comprise the delta plain. These result in the development of an aquiclude above which paludal conditions develop, promoting accumulation of organic matter. In contrast, there is a low proportion of mixed layer and expandable clays transported in the Mahakam River system. This precludes the development of a stilted water table within the delta, allowing for organic matter recycling without peat accumulation. The presence of a high proportion of expandable clay minerals on the western side of Borneo is a reflection of the weathering and eroding source rocks on this side of the

C1-C2 alkyl aminiums in urban aerosols: Insights from ambient and fuel combustion emission measurements in the Yangtze River Delta region of China

International Nuclear Information System (INIS)

Shen, Wenchao; Ren, Lili; Zhao, Yi; Zhou, Luyu; Dai, Liang; Ge, Xinlei; Kong, Shaofei; Yan, Qin; Xu, Honghui; Jiang, Yujun; He, Jun; Chen, Mindong; Yu, Huan

2017-01-01

We measured low molar-mass alkyl aminiums (methylaminium, dimethylaminium, ethylaminium and diethylaminium) in urban aerosols in the Yangtze River Delta region of eastern China in August 2014 and from November 2015 to May 2016. After examining artifact formation on sample filters, methylaminium, dimethylaminium and ethylaminium concentrations were quantified. The three C1-C2 aminiums exhibited a unimodal size distribution that maximized between 0.56 and 1.0 μm. Their concentrations in PM 2.5 were 5.7 ± 3.2 ng m −3 , 7.9 ± 5.4 ng m −3 and 20.3 ± 16.6 ng m −3 , respectively, with higher concentrations during the daytime and in warm seasons. On new particle growth days, amine uptake to particles larger than 56 nm was barely enhanced. The molar ratios of individual aminium/NH 4 + in PM 2.5 were on the order of 10 −4 and 10 −3 . Aminiums were thus far less to out-compete ammonium (NH 4 + ) in neutralizing acidic species in particle sizes down to 56 nm. Abundant nitrate (NO 3 − /SO 4 2− molar ratio = ∼3) and its correlation to methylaminium and ethylaminium implied that nitrate might be more important aminium salt than sulfate in urban aerosols of this area. Direct measurement of particle-phase amine emission from coal and biomass burning showed that coal burning is an important atmospheric amine source, considering coal burning is top-ranked particulate matter source in China. - Highlights: • Aminium concentration showed seasonal and diurnal variations in urban aerosols of our area. • Nitrate was more important aminium salt than sulfate in urban aerosols of our area. • Particle-phase amine emission from coal burning is an important atmospheric amine source. • Amine uptake to particles larger than 56 nm was barely enhanced on new particle growth events. • Aminiums cannot out-compete ammonium in neutralizing acidic species in urban aerosols with particle sizes down to 56 nm. - Aminiums cannot out-compete ammonium in

Response of benthic foraminifera to 4.2 ka cooling event in the Nakdong River delta, southeast Korea

Science.gov (United States)

Takata, H.; Khim, B. K.; Cheong, D.; Shin, S.

2016-02-01

Here we report the change of benthic foraminifera in response to 4.2 ka cooling event in the Nakdong River delta (southeastern Korea). It has been known that this cooling event caused climatic deteriorations in the world, which is closely related to the decline/development of the civilizations (e.g., Kawahata et al., 2009). This event was also correlated to one of Bond Events in the North Atlantic. Because coastal sediment depositions have been influenced by both oceanographic and terrestrial climatic changes, the study may provide us clue to understand the possible teleconnection of the cooling event between the North Atlantic and the East Asian margin. We investigated fossil benthic foraminiferal faunas and planktonic/total foraminiferal ratio (P/T ratio) at two borehole cores, ND-01 and ND-02 (landward and seaward sites, respectively). Common constituents are taxa from bay to shelf environments in the East Asian margin. Biotic response of benthic foraminifera partly changed after 4.2 ka showing that Haynesina sp. A (opportunistic species?) decreased significantly at core ND-01. In addition, P/T ratio at both core sites showed temporal decline at 4.2 ka. This suggests the decreasing influence of the seawater relative to the coastal water. Holocene fluctuations of the Tsushima Warm Current, a branch of Kuroshio, flowing off the Nakdong River delta, have been documented. The decline pattern of P/T ratio in this area is similar to that of total sulfur content in Lake Tougou-ike, southwestern Japan at 4 ka which was interpreted as the influence of the small sea-level falling (Kato et al., 2003). According to the similar stratigraphic variation patterns between our and their studies, our finding suggests that this event was not regional but related to the fluctuations of the Tsushima Warm Current. Thus, biotic response of benthic foraminifera in the Nakdong River delta recorded 4.2 ka cooling event related to temporal weakening of the Tsushima Warm Current.

A DYNAMIC APPROACH TO CALCULATE SHADOW PRICES OF WATER RESOURCES FOR NINE MAJOR RIVERS IN CHINA

Institute of Scientific and Technical Information of China (English)

Jing HE; Xikang CHEN; Yong SHI

2006-01-01

China is experiencing from serious water issues. There are many differences among the Nine Major Rivers basins of China in the construction of dikes, reservoirs, floodgates, flood discharge projects, flood diversion projects, water ecological construction, water conservancy management, etc.The shadow prices of water resources for Nine Major Rivers can provide suggestions to the Chinese government. This article develops a dynamic shadow prices approach based on a multiperiod input-output optimizing model. Unlike previous approaches, the new model is based on the dynamic computable general equilibrium (DCGE) model to solve the problem of marginal long-term prices of water resources.First, definitions and algorithms of DCGE are elaborated. Second, the results of shadow prices of water resources for Nine Major Rivers in 1949-2050 in China using the National Water Conservancy input-holding-output table for Nine Major Rivers in 1999 are listed. A conclusion of this article is that the shadow prices of water resources for Nine Major Rivers are largely based on the extent of scarcity.Selling prices of water resources should be revised via the usage of parameters representing shadow prices.

Effects of middle-term land reclamation on nickel soil-water interaction: a case study from reclaimed salt marshes of Po River Delta, Italy.

Science.gov (United States)

Di Giuseppe, Dario; Melchiorre, Massimiliano; Faccini, Barbara; Ferretti, Giacomo; Coltorti, Massimo

2017-09-26

Reclaimed salt marshes are fragile environments where water salinization and accumulation of heavy metals can easily occur. This type of environment constitutes a large part of the Po River Delta (Italy), where intensive agricultural activities take place. Given the higher Ni background of Po River Delta soils and its water-soluble nature, the main aim of this contribution is to understand if reclamation can influence the Ni behavior over time. In this study, we investigated the geochemical features of 40 soils sampled in two different localities from the Po River Delta with different reclamation ages. Samples of salt marsh soils reclaimed in 1964 were taken from Valle del Mezzano while soils reclaimed in 1872 were taken nearby Codigoro town. Batch solubility tests and consecutive determination of Ni in pore-water were compared to bulk physicochemical compositions of soils. Bulk Ni content of the studied soils is naturally high, since these soils originated from Po River sediments derived from the erosion of ultramafic rocks. Moreover, it seems that Ni concentration increases during soil evolution, being probably related to the degradation of serpentine. Instead, the water-soluble Ni measured in the leaching tests is greater in soils recently reclaimed compared to the oldest soils. Soil properties of two soil profiles from a reclaimed wetland area were examined to determine soil evolution over one century. Following reclamation, pedogenic processes of the superficial horizons resulted in organic matter mineralization, pH buffer, and a decrease of Ni water solubility from recently to evolved reclaimed soil.

Characteristics of fine particulate matter and its sources in an industrialized coastal city, Ningbo, Yangtze River Delta, China

Science.gov (United States)

Wang, Weifeng; Yu, Jie; Cui, Yang; He, Jun; Xue, Peng; Cao, Wan; Ying, Hongmei; Gao, Wenkang; Yan, Yingchao; Hu, Bo; Xin, Jinyuan; Wang, Lili; Liu, Zirui; Sun, Yang; Ji, Dongsheng; Wang, Yuesi

2018-05-01

Chemical information is essential in understanding the characteristics of airborne particles, and effectively controlling airborne particulate matter pollution, but it remains unclear in some regions due to the scarcity of measurement data. In the present study, 92 daily PM2.5 (particulate matter with an aerodynamic diameter ≤ 2.5 μm) samples as well as historical observation data of air pollutants were collected in urban Ningbo, one of important industrial cities in the coastal area of the Yangtze River Delta, China in autumn and winter (from Nov. 2014 to Feb. 2015). Various chemical species in PM2.5 were determined including water soluble ions, organic and elemental carbon and elements. Positive matrix factorization model, cluster analysis of back trajectories, potential source contribution function (PSCF) model and concentration-weighted trajectory (CWT) model were used for identifying sources, apportioning contributions from each source and tracking potential areas of sources. The results showed the PM2.5 concentration has been reducing; nonetheless, the concentrations of PM2.5 are still much higher than the World Health Organization guideline with high PM2.5 concentrations observed in autumn and winter for the past few years. During the sampling period, the average PM2.5 mass concentration was 77 μg/m3 with the major components of OC, NO3-, SO42 -, NH4+ and EC, accounting for 24.7, 18.8, 14.5, 11.8 and 6.4% in the total mass concentration, respectively. When the aerosol pollution got worse during the sampling period, the NO3-, SO42 - and NH4+ concentrations increased accordingly and NO3- appeared to increase at fastest rate. SO42 - transported from industrial areas led to slight difference in spatial distribution of SO42 - in Ningbo. More secondary organic carbon was formed and the enrichment factor values of Cu, Ag, Cd, Sn and Pb increased with the degradation of air quality. Ten types of sources were identified for PM2.5 in the autumn and winter of

Dynamic controls on shallow clinoform geometry: Mekong Delta, Vietnam

Science.gov (United States)

Eidam, E. F.; Nittrouer, C. A.; Ogston, A. S.; DeMaster, D. J.; Liu, J. P.; Nguyen, T. T.; Nguyen, T. N.

2017-09-01

Compound deltas, composed of a subaerial delta plain and subaqueous clinoform, are common termini of large rivers. The transition between clinoform topset and foreset, or subaqueous rollover point, is located at 25-40-m water depth for many large tide-dominated deltas; this depth is controlled by removal of sediment from the topset by waves, currents, and gravity flows. However, the Mekong Delta, which has been classified as a mixed-energy system, has a relatively shallow subaqueous rollover at 4-6-m depth. This study evaluates dynamical measurements and seabed cores collected in Sep 2014 and Mar 2015 to understand processes of sediment transfer across the subaqueous delta, and evaluate possible linkages to geometry. During the southwest rainy monsoon (Sep 2014), high river discharge, landward return flow under the river plume, and regional circulation patterns facilitated limited sediment flux to the topset and foreset, and promoted alongshore flux to the northeast. Net observed sediment fluxes in Sep 2014 were landward, however, consistent with hypotheses about seasonal storage on the topset. During the northeast rainy monsoon, low river discharge and wind-driven currents facilitated intense landward and southwestward fluxes of sediment. In both seasons, bed shear velocities frequently exceeded the 0.01-0.02 m/s threshold of motion for sand, even in the absence of strong wave energy. Most sediment transport occurred at water depths 4 cm/yr at energy-limited, and thus rollover depths cannot be predicted solely by bed-stress distributions. In systems like the subaqueous Mekong Delta, direction of transport may have a key impact on morphology.

Significant concentration changes of chemical components of PM_1 in the Yangtze River Delta area of China and the implications for the formation mechanism of heavy haze–fog pollution

International Nuclear Information System (INIS)

Zhang, Y.W.; Zhang, X.Y.; Zhang, Y.M.; Shen, X.J.; Sun, J.Y.; Ma, Q.L.; Yu, X.M.; Zhu, J.L.; Zhang, L.; Che, H.C.

2015-01-01

Since the winter season of 2013, a number of persistent haze–fog events have occurred in central-eastern China. Continuous measurements of the chemical and physical properties of PM_1 at a regional background station in the Yangtze River Delta area of China from 16 Nov. to 18 Dec., 2013 revealed several haze–fog events, among which a heavy haze–fog event occurred between 6 Dec. and 8 Dec. The mean concentration of PM_1 was 212 μg m"−"3 in the heavy haze–fog period, which was about 10 times higher than on clean days and featured a peak mass concentration that reached 298 μg m"−"3. Organics were the largest contributor to the dramatic rise of PM_1 on heavy haze–fog days (average mass concentration of 86 μg m"−"3), followed by nitrate (58 μg m"−"3), sulfate (35 μg m"−"3), ammonium (29 μg m"−"3), and chloride (4.0 μg m"−"3). Nitrate exhibited the largest increase (~ 20 factors), associated with a significant increase in NO_x. This was mainly attributable to increased coal combustion emissions, relative to motor vehicle emissions, and was caused by short-distance pollutant transport within surrounding areas. Low-volatility oxidized organic aerosols (OA) (LV-OOA) and biomass-burning OA (BBOA) also increased sharply on heavy haze–fog days, exhibiting an enhanced oxidation capacity of the atmosphere and increased emissions from biomass burning. The strengthening of the oxidation capacity during the heavy pollution episode, along with lower solar radiation, was probably due to increased biomass burning, which were important precursors of O_3. The prevailing meteorological conditions, including low wind and high relative humidity, and short distance transported gaseous and particulate matter surrounding of the sampling site, coincided with the increased pollutant concentrations mainly from biomass-burning mentioned above to cause the persistent haze–fog event in the YRD area. - Highlights: • Formation mechanism of a heavy haze-fog event

An ozone episode in the Pearl River Delta: Field observation and model simulation

Science.gov (United States)

Jiang, F.; Guo, H.; Wang, T. J.; Cheng, H. R.; Wang, X. M.; Simpson, I. J.; Ding, A. J.; Saunders, S. M.; Lam, S. H. M.; Blake, D. R.

2010-11-01

In the fall of 2007 concurrent air sampling field measurements were conducted for the first time in Guangzhou (at Wan Qing Sha (WQS)) and Hong Kong (at Tung Chung (TC)), two cities in the rapidly developing Pearl River Delta region of China that are only 62 km apart. This region is known to suffer from poor air quality, especially during the autumn and winter months, when the prevailing meteorological conditions bring an outflow of continental air to the region. An interesting multiday O3 pollution event (daily maximum O3 > 122 ppbv) was captured during 9-17 November at WQS, while only one O3 episode day (10 November) was observed at TC during this time. The mean O3 mixing ratios at TC and WQS during the episode were 38 ± 3 (mean ± 95% confidence interval) and 51 ± 7 ppbv, respectively, with a mean difference of 13 ppbv and a maximum hourly difference of 150 ppbv. We further divided this event into two periods: 9-11 November as Period 1 and 12-17 November as Period 2. The mixing ratios of O3 and its precursors (NOx and CO) showed significant differences between the two periods at TC. By contrast, no obvious difference was found at WQS, indicating that different air masses arrived at TC for the two periods, as opposed to similar air masses at WQS for both periods. The analysis of VOC ratios and their relationship with O3 revealed strong O3 production at WQS during Period 2, in contrast to relatively weak photochemical O3 formation at TC. The weather conditions implied regional transport of O3 pollution during Period 1 at both sites. Furthermore, a comprehensive air quality model system (Weather Research and Forecasting-Community Multiscale Air Quality model (WRF-CMAQ)) was used to simulate this O3 pollution event. The model system generally reproduced the variations of weather conditions, simulated well the continuous high O3 episode event at WQS, and captured fairly well the elevated O3 mixing ratios in Period 1 and low O3 levels in Period 2 at TC. The modeled

Diffusion pollution from livestock and poultry rearing in the Yangtze Delta, China.

Science.gov (United States)

Gu, Pei; Shen, Ren Fang; Chen, Yi Ding

2008-05-01

The Yangtze Delta is one of the most developed regions in China and includes Shanghai, eight cities in Jiangsu province and eight cities in Zhejiang province. Meat consumption in this region has increased with economic growth, and most of the consumed meat is produced locally. The water quality of surface waters has deteriorated in recent years. An example was the huge blue-green algae bloom in Tai Lake in late May 2007, which affected millions of people's daily drinking water. However, animal husbandry is considered to be one of the main pollution sources. Pollutants (NH3-N, total phosphorus (TP), and total nitrogen (TN)) excreted by livestock and poultry, and the resultant COD (chemical oxygen demand) and BOD (biochemical oxygen demand), were estimated using two different methods based on different data sets. The number of livestock and poultry has remained stable in the Yangtze Delta over the four years from 1999 to 2002, with the average number of pigs, cattle, sheep and poultry being 21.1 M, 0.4 M, 7.7 M and 597.6 M, respectively. Pollutants in livestock and poultry excreta estimated by Method I were: 0.12 Mt NH3-N, 0.11 Mt TP and 0.29 Mt TN, resulting in COD and BOD of 1.34 Mt and 1.30 Mt, respectively, while the estimations based on Method II were: 0.18 Mt NH3-N, 0.15 Mt TP and 0.40 Mt TN, resulting in COD and BOD of 1.95 Mt and 1.80 Mt, respectively. Pollutants excreted annually by livestock and poultry in the Yangtze Delta are estimated to be: 0.17 Mt NH3-N, 0.16 Mt TP and 0.42 Mt TN, giving rise to a COD of 1.86 Mt and a BOD of 1.72 Mt. Approximately 25% of this pollution was estimated to enter water bodies, which means that the annual pollutant load is 43,700 t NH3-N, 39,400 tTP, 104,600t TN with a COD of 465,000 tand a BOD of 430,100 t. Pollutants from animal husbandry were similar in magnitude to those from industrial wastewater. Pigs produced the most pollution, followed by poultry, cattle and sheep. The pollution load from animal husbandry in the

Impact on water quality of land uses along Thamalakane-Boteti River: An outlet of the Okavango Delta

Science.gov (United States)

Masamba, Wellington R. L.; Mazvimavi, Dominic

Botswana is a semiarid country and yet has one of the world’s famous wetlands: the Okavango Delta. The Thamalakane-Boteti River is one of the Delta’s outlets. The water quality of the Thamalakane-Boteti River was determined and related to its utilisation. The major land uses along the Thamalakane River within Maun are residential areas, lodges, hotels, and grazing by cattle and donkeys. The water is used as a source of water for livestock, wildlife in a game park, horticulture and domestic applications including drinking. The river is also used for fishing. To check whether these activities negatively impact on the water quality, pH, electrical conductivity, dissolved oxygen, temperature, total dissolved nitrogen and phosphorus, Faecal coliforms and Faecal streptococci and selected metals were determined from July 2005 to January 2006. The pH was near neutral except for the southern most sampling sites where values of up to 10.3 were determined. Dissolved oxygen varied from 2 mg/l to 8 mg/l. Sodium (range 0.6-3.2 mg/l), K (0.3-3.6 mg/l), Fe (1.6-6.9 mg/l) conductivity (56-430 μS/cm) and Mg (0.2-6.7 mg/l) increased with increased distance from the Delta, whereas lead showed a slight decline. Total dissolved phosphorus was low (up to 0.02 mg/l) whereas total dissolved nitrogen was in the range 0.08-1.5 mg/l. Faecal coliform (range 0-48 CFU/100 ml) and Faecal streptococci (40-260 CFU/100 ml) were low for open waters with multiple uses. The results indicate that there is possibility of pollution with organic matter and nitrogen. It is recommended that more monitoring of water quality needs to be done and the sources of pollution identified.

Reducing future river export of nutrients to coastal waters of China in optimistic scenarios

NARCIS (Netherlands)

Strokal, Maryna; Kroeze, Carolien; Wang, Mengru; Ma, Lin

2017-01-01

Coastal waters of China are rich in nitrogen (N) and phosphorus (P) and thus often eutrophied. This is because rivers export increasing amounts of nutrients to coastal seas. Animal production and urbanization are important sources of nutrients in Chinese rivers. In this study we explored the

Rapid growth in nitrogen dioxide pollution over Western China, 2005-2013

Science.gov (United States)

Cui, Yuanzheng; Lin, Jintai; Song, Chunqiao; Liu, Mengyao; Yan, Yingying; Xu, Yuan; Huang, Bo

2016-05-01

Western China has experienced rapid industrialization and urbanization since the implementation of the National Western Development Strategies (the "Go West" movement) in 1999. This transition has affected the spatial and temporal characteristics of nitrogen dioxide (NO2) pollution. In this study, we analyze the trends and variability of tropospheric NO2 vertical column densities (VCDs) from 2005 to 2013 over Western China, based on a wavelet analysis on monthly mean NO2 data derived from the Ozone Monitoring Instrument (OMI) measurements. We focus on the anthropogenic NO2 by subtracting region-specific "background" values dominated by natural sources. After removing the background influences, we find significant anthropogenic NO2 growth over Western China between 2005 and 2013 (8.6 ± 0.9 % yr-1 on average, relative to 2005), with the largest increments (15 % yr-1 or more) over parts of several city clusters. The NO2 pollution in most provincial-level regions rose rapidly from 2005 to 2011 but stabilized or declined afterwards. The NO2 trends were driven mainly by changes in anthropogenic emissions, as confirmed by a nested GEOS-Chem model simulation and a comparison with Chinese official emission statistics. The rate of NO2 growth during 2005-2013 reaches 11.3 ± 1.0 % yr-1 over Northwestern China, exceeding the rates over Southwestern China (5.9 ± 0.6 % yr-1) and the three well-known polluted regions in the east (5.3 ± 0.8 % yr-1 over Beijing-Tianjin-Hebei, 4.0 ± 0.6 % yr-1 over the Yangtze River Delta, and -3.3 ± 0.3 % yr-1 over the Pearl River Delta). Subsequent socioeconomic analyses suggest that the rapid NO2 growth over Northwestern China is likely related to the fast developing resource- and pollution-intensive industries along with the "Go West" movement as well as relatively weak emission controls. Further efforts should be made to alleviate NOx pollution to achieve sustainable development in Western China.

Rapid growth in nitrogen dioxide pollution over Western China, 2005-2013

Science.gov (United States)

Cui, Y.-Z.; Lin, J.-T.; Song, C.; Liu, M.-Y.; Yan, Y.-Y.; Xu, Y.; Huang, B.

2015-12-01

Western China has experienced rapid industrialization and urbanization since the implementation of the National Western Development Strategies (the "Go West" movement) in 1999. This transition has affected the spatial and temporal characteristics of nitrogen dioxide (NO2) pollution. In this study, we analyze the trends and variability of tropospheric NO2 vertical column densities (VCDs) from 2005 to 2013 over Western China, based on a wavelet analysis on monthly mean NO2 data derived from the Ozone Monitoring Instrument (OMI) measurements. We focus on the anthropogenic NO2 by subtracting region-specific "background" values dominated by natural sources. We find significant NO2 growth over Western China between 2005 and 2013 (8.6 ± 0.9 % yr-1 on average, relative to 2005), with the largest increments (15 % yr-1 or more) over parts of several city clusters. The NO2 pollution in most provincial regions rose rapidly from 2005 to 2011 but stabilized or declined afterwards. The NO2 trends were driven mainly by changes in anthropogenic emissions, as confirmed by a nested GEOS-Chem model simulation and a comparison with Chinese official emission statistics. The rate of NO2 growth during 2005-2013 reaches 11.3 ± 1.0 % yr-1 over Northwestern China, exceeding the rates over Southwestern China (5.9 ± 0.6 % yr-1) and the three well-known polluted regions in the east (5.3 ± 0.8 % yr-1 over Beijing-Tianjin-Hebei, 4.0 ± 0.6 % yr-1} over the Yangtze River Delta, and -3.3 ± 0.3 % yr-1 over the Pearl River Delta). Additional socioeconomic analyses suggest that the rapid NO2 growth in Northwestern China is likely related to the fast developing resource- and pollution-intensive industries along with the "Go West" movement as well as relatively weak emission controls. Further efforts should be made to alleviate NOx pollution to achieve sustainable development in Western China.