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Sample records for neretva river delta

  1. Nile River Delta, Egypt

    NASA Technical Reports Server (NTRS)

    1984-01-01

    The Nile River Delta of Egypt (30.0N, 31.0E) irrigated by the Nile River and its many distributaries, is some of the richest farm land in the world and home to some 45 million people, over half of Egypt's population. The capital city of Cairo is at the apex of the delta. Just across the river from Cairo can be seen the ancient three big pyramids and sphinx at Giza and the Suez Canal is just to the right of the delta.

  2. Modeling river delta formation.

    PubMed

    Seybold, Hansjörg; Andrade, José S; Herrmann, Hans J

    2007-10-23

    A model to simulate the time evolution of river delta formation process is presented. It is based on the continuity equation for water and sediment flow and a phenomenological sedimentation/erosion law. Different delta types are reproduced by using different parameters and erosion rules. The structures of the calculated patterns are analyzed in space and time and compared with real data patterns. Furthermore, our model is capable of simulating the rich dynamics related to the switching of the mouth of the river delta. The simulation results are then compared with geological records for the Mississippi River. PMID:17940031

  3. Ganges River Delta

    NASA Technical Reports Server (NTRS)

    2002-01-01

    The Ganges River forms an extensive delta where it empties into the Bay of Bengal. The delta is largely covered with a swamp forest known as the Sunderbans, which is home to the Royal Bengal Tiger. It is also home to most of Bangladesh, one of the world's most densely populated countries. Roughly 120 million people live on the Ganges Delta under threat of repeated catastrophic floods due to heavy runoff of meltwater from the Himalayas, and due to the intense rainfall during the monsoon season. This image was acquired by Landsat 7's Enhanced Thematic Mapper plus (ETM+) sensor on February 28, 2000. This is a false-color composite image made using green, infrared, and blue wavelengths. Image provided by the USGS EROS Data Center Satellite Systems Branch

  4. Mackenzie River Delta, Canada

    NASA Technical Reports Server (NTRS)

    2007-01-01

    The Mackenzie River in the Northwest Territories, Canada, with its headstreams the Peace and Finley, is the longest river in North America at 4241 km, and drains an area of 1,805,000 square km. The large marshy delta provides habitat for migrating Snow Geese, Tundra Swans, Brant, and other waterfowl. The estuary is a calving area for Beluga whales. The Mackenzie (previously the Disappointment River) was named after Alexander Mackenzie who travelled the river while trying to reach the Pacific in 1789.

    The image was acquired on August 4, 2005, covers an area of 55.8 x 55.8 km, and is located at 68.6 degrees north latitude, 134.7 degrees west longitude.

    The U.S. science team is located at NASA's Jet Propulsion Laboratory, Pasadena, Calif. The Terra mission is part of NASA's Science Mission Directorate.

  5. Mississippi River Delta

    NASA Technical Reports Server (NTRS)

    2002-01-01

    As the Mississippi River enters the Gulf of Mexico, it loses energy and dumps its load of sediment that it has carried on its journey through the mid continent. This pile of sediment, or mud, accumulates over the years building up the delta front. As one part of the delta becomes clogged with sediment, the delta front will migrate in search of new areas to grow. The area shown on this image is the currently active delta front of the Mississippi. The migratory nature of the delta forms natural traps for oil. Most of the land in the image consists of mud flats and marsh lands. There is little human settlement in this area due to the instability of the sediments. The main shipping channel of the Mississippi River is the broad stripe running northwest to southeast.

    This image was acquired on May 24, 2001 by the Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) on NASA's Terra satellite. With its 14 spectral bands from the visible to the thermal infrared wavelength region, and its high spatial resolution of 15 to 90 meters (about 50 to 300 feet), ASTER will image Earth for the next 6 years to map and monitor the changing surface of our planet.

    ASTER is one of five Earth-observing instruments launched December 18,1999, on NASA's Terra satellite. The instrument was built by Japan's Ministry of Economy, Trade and Industry. A joint U.S./Japan science team is responsible for validation and calibration of the instrument and the data products. Dr. Anne Kahle at NASA's Jet Propulsion Laboratory, Pasadena, California, is the U.S. Science team leader; Bjorn Eng of JPL is the project manager. The Terra mission is part of NASA's Earth Science Enterprise, a long-term research and technology program designed to examine Earth's land, oceans, atmosphere, ice and life as a total integrated system.

    The broad spectral coverage and high spectral resolution of ASTER will provide scientists in numerous disciplines with critical information for surface mapping

  6. Parana River Delta in Argentina

    NASA Technical Reports Server (NTRS)

    2002-01-01

    The Parana River delta is a huge forested marshland about 20 miles northeast of Buenos Aires, Argentina. The area is a very popular tour destination. Guided boat tours can be taken into this vast labyrinth of marsh and trees. The Parana River delta is one of the world's greatest bird-watching destinations. This image highlights the striking contrast between dense forest and wetland marshes, and the deep blue ribbon of the Parana River. This image was acquired by Landsat 7's Enhanced Thematic Mapper plus (ETM+) sensor on May 26, 2000. This is a false-color composite image made using shortwave infrared, near infrared, and green wavelengths. Image provided by the USGS EROS Data Center Satellite Systems Branch.

  7. From Natural to Design River Deltas

    NASA Astrophysics Data System (ADS)

    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.

  8. Lena River Delta formation during the Holocene

    NASA Astrophysics Data System (ADS)

    Bolshiyanov, D.; Makarov, A.; Savelieva, L.

    2014-03-01

    The Lena River Delta, the largest delta of the Arctic Ocean, differs from other deltas because it consists mainly of organomineral sediments, commonly called peat, that contain a huge organic carbon reservoir. The analysis of Delta sediment radiocarbon ages showed that they could not have formed as peat during floodplain bogging, but accumulated when Laptev Sea water level was high and green mosses and sedges grew and were deposited on the surface of flooded marshes. The Lena River Delta formed as organomineral masses and layered sediments accumulated during transgressive phases when sea level rose. In regressive phases, the islands composed of these sediments and other, more ancient islands were eroded. Each new sea transgression led to further accumulation of layered sediments. As a result of alternating transgressive and regressive phases the first alluvial-marine terrace formed, consisting of geological bodies of different ages. Determining the formation age of different areas of the first terrace and other marine terraces on the coast allowed the periods of increasing (8-6 Ka, 4.5-4 Ka, 2.5-1.5 Ka, 0.4-0.2 Ka) and decreasing (5 Ka, 3 Ka, 0.5 Ka) Laptev Sea levels to be distinguished in the Lena Delta area.

  9. Lena River delta formation during the Holocene

    NASA Astrophysics Data System (ADS)

    Bolshiyanov, D.; Makarov, A.; Savelieva, L.

    2015-01-01

    The Lena River delta, the largest delta of the Arctic Ocean, differs from other deltas because it consists mainly of organomineral sediments, commonly called peat, that contain a huge organic carbon reservoir. The analysis of delta sediment radiocarbon ages showed that they could not have formed as peat during floodplain bogging; rather, they accumulated when Laptev Sea water level was high and green mosses and sedges grew and were deposited on the surface of flooded marshes. The Lena River delta formed as organomineral masses and layered sediments accumulated during transgressive phases when sea level rose. In regressive phases, the islands composed of these sediments and other, more ancient islands were eroded. Each new sea transgression led to further accumulation of layered sediments. As a result of alternating transgressive and regressive phases, the first alluvial-marine terrace formed, consisting of geological bodies of different ages. Determining the formation age of different areas of the first terrace and other marine terraces on the coast allowed the periods of increasing (8000-6000 BP (years before present), 4500-4000, 2500-1500, and 400-200 BP) and decreasing (5000, 3000, and 500 BP) Laptev Sea levels to be distinguished in the Lena Delta area.

  10. Tidal river dynamics: Implications for deltas

    NASA Astrophysics Data System (ADS)

    Hoitink, A. J. F.; Jay, D. A.

    2016-03-01

    Tidal rivers are a vital and little studied nexus between physical oceanography and hydrology. It is only in the last few decades that substantial research efforts have been focused on the interactions of river discharge with tidal waves and storm surges into regions beyond the limit of salinity intrusion, a realm that can extend inland hundreds of kilometers. One key phenomenon resulting from this interaction is the emergence of large fortnightly tides, which are forced long waves with amplitudes that may increase beyond the point where astronomical tides have become extinct. These can be larger than the linear tide itself at more landward locations, and they greatly influence tidal river water levels and wetland inundation. Exploration of the spectral redistribution and attenuation of tidal energy in rivers has led to new appreciation of a wide range of consequences for fluvial and coastal sedimentology, delta evolution, wetland conservation, and salinity intrusion under the influence of sea level rise and delta subsidence. Modern research aims at unifying traditional harmonic tidal analysis, nonparametric regression techniques, and the existing understanding of tidal hydrodynamics to better predict and model tidal river dynamics both in single-thread channels and in branching channel networks. In this context, this review summarizes results from field observations and modeling studies set in tidal river environments as diverse as the Amazon in Brazil, the Columbia, Fraser and Saint Lawrence in North America, the Yangtze and Pearl in China, and the Berau and Mahakam in Indonesia. A description of state-of-the-art methods for a comprehensive analysis of water levels, wave propagation, discharges, and inundation extent in tidal rivers is provided. Implications for lowland river deltas are also discussed in terms of sedimentary deposits, channel bifurcation, avulsion, and salinity intrusion, addressing contemporary research challenges.

  11. Quantitative Metrics of Robustness in River Deltas

    NASA Astrophysics Data System (ADS)

    Foufoula-Georgiou, E.; Tejedor, A.; Longjas, A.; Zaliapin, I. V.

    2014-12-01

    Deltas are landforms with channels that deliver water, sediment and nutrient fluxes from rivers to oceans or inland water bodies via multiple pathways. We conceptualize a delta channel network as a rooted acyclic directed graph where channels are modeled by edges and junctions by vertices. We use spectral graph theory - mainly the geometry of the null space of the directed weighted graph Laplacian - to establish a quantitative framework for extracting important structural and dynamics-related information from river deltas. Using this information, we introduce refined metrics of system complexity, such as entropy. Entropy has been proven to be an important measure of the amount of uncertainty in stochastic systems, and therefore a surrogate of the capacity of the system to undergo changes. Here we present an entropic approach to evaluate the robustness of deltas, showing how the two components of entropy: mutual information and conditional entropy can be interpreted in this framework. We also present other metrics that include, among others, resistance distance and number of alternative paths, which quantify the structural complexity of the system. We use these metrics to better classify deltaic systems, quantify their resilience and propose possible management scenarios.

  12. Zooplankton community and hydrographical properties of the Neretva Channel (eastern Adriatic Sea)

    NASA Astrophysics Data System (ADS)

    Vidjak, Olja; Bojanić, Natalia; Kušpilić, Grozdan; Ninčević Gladan, Živana; Tičina, Vjekoslav

    2007-12-01

    Temporal and spatial variability of micro and mesozooplankton was studied in 1998 and 1999 at four stations in the Neretva Channel area influenced by the Neretva river and the open waters of the south Adriatic Sea. The area is orthophosphate limited, but an excessive accumulation of land derived nitrogen is prevented by phytoplankton uptake and the general circulation pattern. Microzooplankton was dominated by ciliates, with average abundances comparable to other Adriatic channel areas (122 543 ind. l-1). Non-loricate ciliates (NLC) generally peaked in the warmer periods, but a winter increase was evident towards the inner part of the channel. Tintinnid abundances generally increased in autumn. A significant relationship with temperature was not recorded for either protozoan group. An inverse relationship between NLC and salinity might be indirectly caused by their preference for the food abundant surface layer. Mesozooplankton was dominated by copepods, with distinct summer maxima throughout the area and pronounced winter maxima of >10,000 ind. m-3 at the inner stations. The community was predominantly neritic but the open sea waters were important in structuring the mesozooplankton assemblage at all stations during the autumn winter period. Although temperature regulated the seasonal dynamics of most metazoans and the species succession in the copepod community, small omnivorous copepods ( Oncaea media complex, Oithona nana and Euterpina acutifrons) dominated regardless of the season. A trophic link between copepods and ciliates was evident in winter during low phytoplankton biomass.

  13. Elwha River Delta: Geomorphology of a Mixed-Sediment Beach

    NASA Astrophysics Data System (ADS)

    George, D. A.; Warrick, J. J.

    2007-12-01

    The Elwha River drains the Olympic Peninsula of Washington and forms a mixed grain-size delta in the Strait of Juan de Fuca. The Elwha River has been dammed for almost a century, and a pending dam removal project is expected to reconnect upstream sediment sources to the river mouth. Topographic and grain-size mapping of the delta during 1939-2007 is synthesized and the geomorphology and shoreline changes of this system are described. Data sources include historical aerial photographs, airborne LIDAR, semiannual RTK DGPS topographic surveys and grain-size analyses from digital photographs. The delta is divided into three geomorphic regions: west delta, river mouth and east delta. The river mouth is the most complex region due to the river channel movement, side-channels, and bars immediately offshore of the mouth. The east and west delta differ in beach profile and shoreline change rates. The west delta is steep, cuspate and lacks a low-tide terrace. Further, the west delta has exhibited little semi-annual or inter-annual shoreline change. In contrast, the east delta has a steep foreshore, flat low tide terrace that is dominated by cobble, and a consistent trend of erosion during the surveys. These observations can be used to track coastal changes following dam removal on the Elwha River..

  14. Shoreline change in 48 river deltas: towards indexing erosion as a criterion of delta vulnerability

    NASA Astrophysics Data System (ADS)

    Besset, Manon; Anthony, Edward; Dussouillez, Philippe; Sabatier, François

    2016-04-01

    River deltas are considered as increasingly vulnerable to environmental modifications resulting from climate change and human activities. Delta vulnerability is associated with a number of drivers, chief among which are depleted sediment supply, changes in water discharge, and pumping of underground fluids. These activities lead to accelerated subsidence and erosion, the twin mechanisms of delta destruction. A lot of attention has been focused on vulnerability resulting from accelerated subsidence. Here, we address the problem of delta erosion based on the analysis of 48 deltas, including 30 of the world's largest deltas. Using satellite images (Landsat, Spot 5, Spot 6) and aerial photographs, we determined for each delta, the change in delta protruberance area over a 30-year period, this being defined as the area of delta protrusion relative to a straight shoreline running across the delta plain and linking the delta to the adjacent non-protruding non-deltaic shoreline. We classified the deltas in terms of net area loss, gain, or stability, the last corresponding to an uncertainty threshold of _0.3% of the delta's protruberance over the 30-year period. The results show that 25 (52%) of the studied set of deltas show area loss, 11 (23%) stability, and 12 (25%) gain. Area loss is more important in deltas with a protruberance area <500 km2 (67% of small deltas) than in the largest deltas (23%), with a protruberance area >500 km2. Besides sediment supply conditions, which are a primary factor in delta erosion, eroding deltas tend to be more commonly subjected to relatively significant levels of wave energy.

  15. 23. OWENS RIVER DELTA JUST NORTH OF CROWLEY LAKE ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    23. OWENS RIVER DELTA JUST NORTH OF CROWLEY LAKE - Los Angeles Aqueduct, From Lee Vining Intake (Mammoth Lakes) to Van Norman Reservoir Complex (San Fernando Valley), Los Angeles, Los Angeles County, CA

  16. Ecosystem Services Assessment of the Nemunas River Delta

    EPA Science Inventory

    The concept of ecosystem services recognizes the services, and benefits, provided to people by ecosystems. The Nemunas River Delta, in Lithuania, provides many ecosystem services to the people of the area, including food, fuel, transportation, climate regulation, water purificati...

  17. Altamaha River Delta, Georgia Sea Islands

    NASA Technical Reports Server (NTRS)

    2001-01-01

    The history of sea islands in the Altamaha River delta on the coast of Georgia is revealed in this image produced from data acquired by the Airborne Synthetic Aperture Radar (AIRSAR), developed and operated by NASA's Jet Propulsion Laboratory, Pasadena, Calif. The outlines of long-lost plantation rice fields, canals, dikes and other inlets are clearly defined. Salt marshes are shown in red, while dense cypress and live oak tree canopies are seen in yellow-greens.

    Agricultural development of the Altamaha delta began soon after the founding of the Georgia Colony in 1733. About 25 plantations were located on the low-lying islands and shores by the 19th century, taking advantage of the rich alluvial flow and annual inundation of water required by some crops. The first major crop was indigo; when demand for that faded, rice and cotton took its place. A major storm in 1824 destroyed much of the town of Darien (upper right) and put many of the islands under 20 feet of water. The Civil War ended the plantation system, and many of the island plantations disappeared under heavy brush and new growth pine forests. Some were used as tree farms for paper and pulp industries, while the Butler Island (center left) plantation became a wildlife conservation site growing wild sea rice for migrating ducks and other waterfowl. Margaret Mitchell is reputed to have used the former owner of the Butler Plantation as a basis for the Rhett Butler character in her novel 'Gone With The Wind,' taking the first name from Rhett's Island (lower right).

    These data were obtained during a 1994-95 campaign along the Georgia coast. AIRSAR's ability to detect vegetation canopy density, hydrological features and other topographic characteristics is a useful tool in landscape archaeology. AIRSAR flies aboard a NASA DC-8 based at NASA's Dryden Flight Research Center, Edwards, Calif. The analysis on the data shown was accomplished by Dr. Gary Mckay, Department of Archaeology and Geography, and Ian

  18. Morphology of river deltas on Titan and Earth

    NASA Astrophysics Data System (ADS)

    Witek, Piotr; Czechowski, Leszek

    2016-07-01

    The Cassini-Huygens mission is entering its final phase. The landing of Huygens on Titan and flybys performed by the Cassini probe during the last ten years revolutionized our knowledge about that moon, revealing a complex fluvio-lacustrine environment. Despite significant differences in composition, temperature and gravity, the processes of sediment transport and deposition are similar on Earth and Titan. We performed numerical simulations of development of river deltas in Titanian and terrestrial conditions, under various discharges and with different dominant grain sizes. We found that evolution of deltaic deposits is more rapid on Titan due to higher efficiency of transport, but the flat, lobate river deltas may form in narrower range of parameters than on Earth. Our results help in understanding the evolution of sedimentary deposits and may partially explain the paucity of river deltas in Titan's lakes.

  19. Quantitative metrics that describe river deltas and their channel networks

    NASA Astrophysics Data System (ADS)

    Edmonds, Douglas A.; Paola, Chris; Hoyal, David C. J. D.; Sheets, Ben A.

    2011-12-01

    Densely populated river deltas are losing land at an alarming rate and to successfully restore these environments we must understand the details of their morphology. Toward this end we present a set of five metrics that describe delta morphology: (1) the fractal dimension, (2) the distribution of island sizes, (3) the nearest-edge distance, (4) a synthetic distribution of sediment fluxes at the shoreline, and (5) the nourishment area. The nearest-edge distance is the shortest distance to channelized or unchannelized water from a given location on the delta and is analogous to the inverse of drainage density in tributary networks. The nourishment area is the downstream delta area supplied by the sediment coming through a given channel cross section and is analogous to catchment area in tributary networks. As a first step, we apply these metrics to four relatively simple, fluvially dominated delta networks. For all these deltas, the average nearest-edge distances are remarkably constant moving down delta suggesting that the network organizes itself to maintain a consistent distance to the nearest channel. Nourishment area distributions can be predicted from a river mouth bar model of delta growth, and also scale with the width of the channel and with the length of the longest channel, analogous to Hack's law for drainage basins. The four delta channel networks are fractal, but power laws and scale invariance appear to be less pervasive than in tributary networks. Thus, deltas may occupy an advantageous middle ground between complete similarity and complete dissimilarity, where morphologic differences indicate different behavior.

  20. Underground and Previously Undiscovered Rivers in the Mississippi Delta

    NASA Astrophysics Data System (ADS)

    Kolker, A.; Breaux, A.; Coleman, D.; Inniss, L. V.; Telfeyan, K.; Kim, J.; Schneider, A.; Allison, M. A.; Cable, J. E.; Johannesson, K. H.

    2013-12-01

    In this study we show that there are large, and previously undiscovered, groundwater pathways by which water from the Mississippi River is transported to the wetlands and estuaries of the Mississippi River Delta. Results from multiple methodologies suggest that the total flux of groundwater to the coastal zone in the Mississippi River Delta averages 1,000 m3 s-1, and can reach 5,000 m3 s-1 at high flow. We suggest that flow preferentially occurs through paleo-crevasse channels, relict bayous, and other buried deposits of permeable and coarse grained material. These conduits were formed during the present and previous stages of the delta cycle, which occurred in historical (102 y) and late Holocene(103 y) times, respectively. Flow is driven by the hydrological head difference between the river and the estuary, which is seasonally variable in magnitudeand can reach 5-8 m during peak river floods. This talk will present data from hydrological budgets that show a missing fraction in the Mississippi River water budget, and a missing source of fresh water to a large estuary. We will show that water levels in wells in New Orleans fluctuate with the stage of the Mississippi River. Data of Rn concentration indicate advective submarine groundwater flow, whereas Ba concentrations suggest geochemical leachates are entering the estuary. Furthermore, seismic data indicate the prevalence of paleochannels and other buried features that could carry flow. Given the importance of deltas to global geochemical budgets, we suggest that these results may be generalizable: submarine groundwater discharge in deltas may prove to be an important but understudied pathway by which dissolved materials are transported from the continents to the ocean.

  1. Sandy River Delta Habitat Restoration Project, Annual Report 2001.

    SciTech Connect

    Kelly, Virginia; Dobson, Robin L.

    2002-11-01

    The Sandy River Delta is located at the confluence of the Sandy and Columbia Rivers, just east of Troutdale, Oregon. It comprises about 1,400 land acres north of Interstate 84, managed by the USDA Forest Service, and associated river banks managed by the Oregon Division of State Lands. Three islands, Gary, Flag and Catham, managed by Metro Greenspaces and the State of Oregon lie to the east, the Columbia River lies to the north and east, and the urbanized Portland metropolitan area lies to the west across the Sandy River. Sandy River Delta was historically a wooded, riparian wetland with components of ponds, sloughs, bottomland woodland, oak woodland, prairie, and low and high elevation floodplain. It has been greatly altered by past agricultural practices and the Columbia River hydropower system. Restoration of historic landscape components is a primary goal for this land. The Forest Service is currently focusing on restoration of riparian forest and wetlands. Restoration of open upland areas (meadow/prairie) would follow substantial completion of the riparian and wetland restoration. The Sandy River Delta is a former pasture infested with reed canary grass, blackberry and thistle. The limited over story is native riparian species such as cottonwood and ash. The shrub and herbaceous layers are almost entirely non-native, invasive species. Native species have a difficult time naturally regenerating in the thick, competing reed canary grass, Himalayan blackberry and thistle. A system of drainage ditches installed by past owners drains water from historic wetlands. The original channel of the Sandy River was diked in the 1930's, and the river diverted into the ''Little Sandy River''. The original Sandy River channel has subsequently filled in and largely become a slough. The FS acquired approximately 1,400 acres Sandy River Delta (SRD) in 1991 from Reynolds Aluminum (via the Trust for Public Lands). The Delta had been grazed for many years but shortly after FS

  2. A reduced-complexity model for river delta formation - Part 1: Modeling deltas with channel dynamics

    NASA Astrophysics Data System (ADS)

    Liang, M.; Voller, V. R.; Paola, C.

    2014-07-01

    We develop a reduced-complexity model (RCM) delta formation model, in contrast to reductionist models based on high-resolution computational fluid dynamics. The basic framework of this model (referred in this paper as "DeltaRCM") consists of stochastic parcel-based cellular routing schemes for water and sediment and a set of phenomenological rules for sediment deposition and erosion. The outputs of the model include flow field, water surface topography and bed topography that evolves in time. Results show that DeltaRCM is able to: (1) resolve a wide range of channel dynamics, including elongation, bifurcation, avulsion and migration; (2) in response to the changes in input parameters, produce different types of deltas such as alluvial fan deltas at experimental scale. We also identify three key areas of particular model sensitivity, even at the RCM level: (1) avulsion dynamics is sensitive to dynamic free-surface topography; (2) channel network structure is sensitive to instability at channel mouths which creates bars; and (3) out-of-channel sedimentation is sensitive to water surface slope along channel margins. We also demonstrate a simple stratigraphy tracking component which can display the structure of the deposit in terms of distribution of coarse and fine materials along with the age of the deposit. DeltaRCM is a useful tool for understanding the dynamics of river deltas within a relatively simple cellular representation of water and sediment transport.

  3. Seismic stability of the Duwamish River Delta, Seattle, Washington

    USGS Publications Warehouse

    Kayen, Robert E.; Barnhardt, Walter A.

    2007-01-01

    The delta front of the Duwamish River valley near Elliott Bay and Harbor Island is founded on young Holocene deposits shaped by sea-level rise, episodic volcanism, and seismicity. These river-mouth deposits are highly susceptible to seismic soil liquefaction and are potentially prone to submarine landsliding and disintegrative flow failure. A highly developed commercial-industrial corridor, extending from the City of Kent to the Elliott Bay/Harbor Island marine terminal facilities, is founded on the young Holocene deposits of the Duwamish River valley. The deposits of this Holocene delta have been shaped not only by relative sea-level rise but also by episodic volcanism and seismicity. Ground-penetrating radar (GPR), cores, in situ testing, and outcrops are being used to examine the delta stratigraphy and to infer how these deposits will respond to future volcanic eruptions and earthquakes in the region. A geotechnical investigation of these river-mouth deposits indicates high initial liquefaction susceptibility during earthquakes, and possibly the potential for unlimited-strain disintegrative flow failure of the delta front.

  4. Ecosystem Services Assessment of the Nemunas River Delta

    EPA Science Inventory

    The concept of ecosystem services recognizes the services, and benefits, provided to people by ecosystems. The Nemunas River Delta, in Lithuania, is a valued area that can provide a range of services. We conducted a meta-analysis of existing studies done on the region to identify...

  5. Pen Branch Delta and Savannah River Swamp Hydraulic Model

    SciTech Connect

    Chen, K.F.

    1999-05-13

    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.

  6. Urban growth and environmental impacts in Jing-Jin-Ji, the Yangtze, River Delta and the Pearl River Delta

    NASA Astrophysics Data System (ADS)

    Haas, Jan; Ban, Yifang

    2014-08-01

    This study investigates land cover changes, magnitude and speed of urbanization and evaluates possible impacts on the environment by the concepts of landscape metrics and ecosystem services in China's three largest and most important urban agglomerations: Jing-Jin-Ji, the Yangtze River Delta and the Pearl River Delta. Based on the classifications of six Landsat TM and HJ-1A/B remotely sensed space-borne optical satellite image mosaics with a superior random forest decision tree ensemble classifier, a total increase in urban land of about 28,000 km2 could be detected alongside a simultaneous decrease in natural land cover classes and cropland. Two urbanization indices describing both speed and magnitude of urbanization were derived and ecosystem services were calculated with a valuation scheme adapted to the Chinese market based on the classification results from 1990 and 2010 for the predominant land cover classes affected by urbanization: forest, cropland, wetlands, water and aquaculture. The speed and relative urban growth in Jing-Jin-Ji was highest, followed by the Yangtze River Delta and Pearl River Delta, resulting in a continuously fragmented landscape and substantial decreases in ecosystem service values of approximately 18.5 billion CNY with coastal wetlands and agriculture being the largest contributors. The results indicate both similarities and differences in urban-regional development trends implicating adverse effects on the natural and rural landscape, not only in the rural-urban fringe, but also in the cities' important hinterlands as a result of rapid urbanization in China.

  7. [Forest biomass and its dynamics in Pearl River Delta].

    PubMed

    Yang, Kun; Guan, Dong-Sheng

    2007-04-01

    Based on the observation data obtained from 69 sampling sites of different age class forests, and by using biomass expansion factor function, the regression equations of stand biomass and volume of the main forest types in Pearl River Delta were built, and the regional forest biomass and its dynamics were estimated on the basis of forest inventory data. The results showed that most of the forests in Pearl River Delta were of young-medium age, which occupied 80% or more of the total forest area, and their undergrowth biomass accounted for about 33% of the total forest biomass, indicating that the regional forest biomass could be estimated more exactly if undergrowth biomass was fully concerned. In the periods of 1989-1993, 1994-1998 and 1999-2003, the forest biomass in Pearl River Delta increased by 14. 67 x 10(6) t in total, among which, Pinus massoniana forest, evergreen broadleaf forest, and conifer and deciduous mixed forest contributed about 80%. Young-medium age forest biomass accounted for 90% of the total, but the proportion was decreased gradually. The forest area in the Delta almost kept unvaried, and the forest biomass was increasing year after year, with an annual increment of about 1.2%. Better fostering and managing the existing forests is very important to have more forest biomass and better environmental effect that regional forests offered.

  8. Coastal eutrophication near the Mississippi river delta

    NASA Astrophysics Data System (ADS)

    Turner, R. Eugene; Rabalais, Nancy N.

    1994-04-01

    CHANGES in delivery of river-borne nutrients such as dissolved phosphate, nitrate and silicate, owing to land-use changes and anthropogenic emissions, are known to result in eutrophication1- enhanced phytoplankton blooms-and more severe hypoxic events2-1 in many enclosed bays and seas. Although similar ecological effects might be expected on continental shelves, the occurrence of such eutrophication has remained unresolved5. Here we present evidence of eutrophication of the continental shelf near the outflow of the Mississippi river, obtained by quantifying biologically bound silica (BSi) in diatom remnants within dated sediment cores. BSi accumulation rates are greatest in water depths of 20 to 50 m within 100 km of the river mouth, and have increased by as much as 100% this century. The increases were substantial by 1980, by which time riverine nitrogen loading had doubled relative to the beginning of the century, even though the silica loading had declined by 50% over the same period. Thus changes in river-borne nutrient loadings can modify coastal food webs and affect the amount and distribution of oxygen in bottom waters on the scale of continental shelves.

  9. Mackenzie River Delta morphological change based on Landsat time series

    NASA Astrophysics Data System (ADS)

    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

  10. Fluvial transport on Titan: formation and evolution of river deltas

    NASA Astrophysics Data System (ADS)

    Witek, Piotr Przemyslaw; Czechowski, Leszek

    2016-10-01

    The Cassini-Huygens mission provided numerous observations indicating that processes of sediment transport are currently operating on the surface of Titan. We performed numerical simulations of flow and sediment transport on Titan with particular emphasis on formation of sedimentary landforms in Titan's lakes. We compared the morphology and evolution of landforms formed in Titanian and terrestrial conditions, under various discharges and with different dominant grain sizes. The processes are similar in both environments; in some cases we observed bifurcation of the flow and switching of the active distributaries. Such processes may lead to abandonment of some delta lobes, as hypothesized for the delta observed in Ontario Lacus on Titan. The lower gravity of Titan and higher buoyancy of the most plausible kinds of sediment result in higher efficiency of transport and generally faster evolution of the deltaic deposits. Our results suggest also that the flat, lobate river deltas may form in narrower range of parameters than on Earth.

  11. Delta Morphodynamics from River Sediment Input: Dam Removal, Elwha River, Washington, USA.

    NASA Astrophysics Data System (ADS)

    Warrick, J. A.; Gelfenbaum, G. R.; Stevens, A. W.; Miller, I. M.; Kaminsky, G. M.; Ritchie, A.

    2015-12-01

    Sediment supply plays an important role in river delta morphodynamics and sustainability, and it is important to evaluate how deltas respond to the restoration or enhancement of sediment supplies. Here we report on the morphodynamic responses of the Elwha River delta to large increases in river sediment loads from the removal of two large dams beginning in 2011. The dam removal project exposed ~30 million tonnes of sediment stored within the former reservoirs to natural erosion by the river, and roughly half of this reservoir sediment was eroded during the first four years of the project. Coastal surveys with GPS-based mapping systems, sonar, and aerial photography have revealed that the Elwha River mouth has expanded seaward by ~500 m with the introduction of new supplies of sediment. Approximately 3.5 million cubic meters (or ~5 million tonnes) of sediment were deposited at the river mouth delta between 2011 and 2015. This newly deposited sediment has been shaped by waves and currents into a series of dynamic bars that have greatly expanded the estuarine habitats of the delta.

  12. Tide and river influences on distributary channels of the Mekong River delta

    NASA Astrophysics Data System (ADS)

    Saito, Y.; Nguyen, V. L.; Ta, T. K. O.; Tamura, T.; Kanai, Y.; Nakashima, R.

    2015-12-01

    The Mekong River delta, one of the world's largest deltas, has extended from Phnom Penh in Cambodia (apex) to the coast from the Saigon River mouth to Cape Camau in Vietnam with a triangular-shape area of more than 60,000 km2. The delta has prograded more than 200 km over at least the last 6-7 ka. The river-mouth area of the delta is meso-tidal with the mean tidal range of 2.5 ± 0.1 m and the maximum tidal range is 3.2-3.8 m. The mean wave height is 0.9 m. Its water discharge is 470 km3/y and its sediment discharge is 160 million t/y, or tenth and ninth largest in the world, respectively. The water discharge varies by season because most of the drainage area is under a monsoonal tropical regime. The flow at Phnom Penh, Cambodia, reaches a maximum in October (typically 39,000 m3/s) and a minimum in May (about 1700 m3/s). Tidal water-level changes are observed in Cambodia, more than 200 km upstream from the river mouth. To understand the combined influenced of river and tide on river bottom sediments, we have collected ~210 surface samples from river bottoms of the whole Mekong River delta in Vietnam, covering five distributaries during dry season from January to May 2015. Sediment characteristics show clearly tide- and river-influenced areas, which are closely linked with river morphology.

  13. Volga River Delta and Caspian Sea

    NASA Technical Reports Server (NTRS)

    2002-01-01

    This true-color MODIS image from May 10, 2002, captures Russia's Volga River (running south through the center) emptying into the northern portion of the Caspian Sea. The waters of the Caspian Sea are quite murky in this image, highlighting the water quality problems plaguing the sea. The sea is inundated with sewage and industrial and agricultural waste, which is having measurable impact on human health and wildlife. According reports from the Department of Energy, in less than a decade the sturgeon catch dropped from 30,000 tons to just over 2,000 tons. National and international groups are currently joining together to find strategies of dealing with the environmental problems of the Caspian Sea. Credit: Jacques Descloitres, MODIS Land Rapid Response Team, NASA/GSFC

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

    NASA Astrophysics Data System (ADS)

    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.

  15. Morphology of river deltas on Earth and Titan

    NASA Astrophysics Data System (ADS)

    Witek, Piotr; Czechowski, Leszek

    2016-04-01

    Presently volatile cycles are known to operate on surfaces of two planetary bodies in the Solar System, Earth and Titan. Fluvial erosion, transport and deposition of rocky material modify parts of the surface. Numerous indications of geologically recent sediment transport have been discovered on Titan by the Cassini-Huygens mission. Theoretical calculations suggest greater mobility of Titanian sediments in comparison to terrestrial, due to lower gravity and lower density of typical crustal material. Using numerical model of flow and sediment transport, we compare the development and morphology of deposits forming in lakes in terrestrial and Titanian conditions. We explore the range of possible river discharges, including natural variability, and several dominant grain sizes. We consider several compositions of sediments on Titan, on Earth we model the transport of quartz grains by water. We perform simulations for the same initial geometry of river channel and lake basin, for a given discharge and dominant grain diameter in each environment. Morphology and evolution of the deltaic deposits are compared. We observe that the erosion has dominant role for the smallest grains, and the effect is more pronounced on Titan than on Earth. The largest grains usually form steep-sloped fan-like deltas on both planetary bodies. The processes of formation and development of the sedimentary landforms are generally similar in both environments. Particular types of deposits may however form in different ranges of discharge and grain size, due to differences in environmental parameters. Greater mobility of sediments on Titan result in easier displacement of loose granular material, especially for smallest considered grains. The flat, lobate deltas can form in narrower range of discharges and grain sizes than on Earth. This fact might be partially responsible for scarcity of river deltas on that active moon, where other signs of fluvial processes are widespread.

  16. Biogeochemical features of aquatic plants in the Selenga River delta

    NASA Astrophysics Data System (ADS)

    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

  17. Bathymetry of the Hong and Luoc River Junction, Red River Delta, Vietnam, 2010

    USGS Publications Warehouse

    Kinzel, Paul J.; Nelson, Jonathan M.; Toan, Duong Duc; Thanh, Mung Dinh; Shimizu, Yasuyuki

    2012-01-01

    The U.S. Geological Survey, in collaboration with the Water Resources University in Hanoi, Vietnam, conducted a bathymetric survey of the junction of the Hong and Luoc Rivers. The survey was done to characterize the channel morphology of this delta distributary network and provide input for hydrodynamic and sediment transport models. The survey was carried out in December 2010 using a boat-mounted multibeam echo sounder integrated with a global positioning system. A bathymetric map of the Hong and Luoc River junction was produced which was referenced to the datum of the Trieu Duong tide gage on the Luoc River.

  18. River, delta and coastal morphological response accounting for biological dynamics

    NASA Astrophysics Data System (ADS)

    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.

  19. Impacts of the Indian Rivers Inter-link Project on Sediment Transport to River Deltas

    NASA Astrophysics Data System (ADS)

    Higgins, S.; Overeem, I.; Syvitski, J. P.

    2015-12-01

    The Indian Rivers Inter-link project is a proposal by the Indian government to link several of India's major rivers via a network of reservoirs and canals. Variations of the IRI have been discussed since 1980, but the current plan has recently received increased support from the Indian government. Construction on three canals has controversially begun. If the Inter-link project moves forward, fourteen canals will divert water from tributaries of the Ganges and Brahmaputra rivers to areas in the west, where fresh water is needed for irrigation. Additional canals would transport Himalayan sediments 500 km south to the Mahanadi delta and more than 1000 km south to the Godavari and Krishna deltas. We investigate the impacts of the proposed diversions on sediment transport to the Mahanadi/Brahmani, Godavari, and Krishna deltas in India and the Ganges-Brahmaputra Delta in Bangladesh. We map the entire river network and the proposed new nodes and connections. Changing watersheds are delineated using the Terrain Analysis Using Digital Elevation Models (TauDEM) Suite. Climate data comes from interpolation between observed precipitation stations located in China, Nepal, India, Bhutan and Bangladesh. Changes in water discharge due to the proposed canals are simulated using HydroTrend, a climate-driven hydrological water balance and transport model that incorporates drainage area, discharge, relief, temperature, basin-average lithology, and anthropogenic influences. Simulated river discharge is validated against observations from gauging stations archived by the Global Runoff Data Center (GRDC). HydroTrend is then used to investigate sediment transport changes that may result from the proposed canals. We also quantify changes in contributing areas for the outlets of nine major Indian rivers, showing that more than 50% of the land in India will contribute a portion of its runoff to a new outlet should the entire canal system be constructed.

  20. Research on vulnerability assessments of the Huanghe (Yellow River) delta

    NASA Astrophysics Data System (ADS)

    qiao, shuqing; shi, xuefa

    2014-05-01

    Coastal zone located at the juncture of the sea, river and land, and under the influence of both land and ocean (including atmosphere), especially the sea-level rise and human activities, are vulnerable to environment and ecology. At highest risk are coastal zone of South, Southeast and East Asia with dense populations, low elevations and inadequate adaptive capacity. In China, more than 40% of the population live on the 15% of the land in coastal area and more than 70% cities located around the coastal area. The Chinese coastal region, especially river delta area has been experienced erosion, seawater intrusion and decrease in biodiversity under the combined influence of sea-level rise, tectonic subsidence and flooding. Furthermore, some kinds of human activity, such as land use, building, dam construction, reclamation from the sea and waste dumping strengthen the vulnerability of environment and ecosystem in coastal region. The coastal hazards (e.g. coastal erosion, seawater intrusion, land subsidence) and vulnerability of the Huanghe (Yelllow River) delta area are studied during the past several years. A systematic coastal assessment index is built and an evaluation model is developed using the development platform of Visual studio.Net 2005. The assessment index system includes two parts, inherent (sea level rise rate, elevation, morphology, water and sediment discharge, mean tidal range, mean wave height etc) and specific vulnerability index (population density, GDP, land utilization, protection structures etc). The assessment index are determined the weight using Analytic hierarchy process (AHP) method. Based on the research results, we better understand the current status and future change of coastal vulnerability and hazards, discuss the impact of the natural possess and human activities. Furthermore, we provide defending strategies for coastal zone vulnerability and typical coastal hazards.

  1. Hydrologic Modeling of a Tropical River Delta by Applying Remote Sensing Data: the Niger Delta and its Distributaries.

    NASA Astrophysics Data System (ADS)

    Hannon, M. T.; Syvitski, J. P.; Kettner, A. J.

    2008-12-01

    Delta regions offer rich resources to coastal human populations with their large upstream freshwater sources. Tropical deltas such as the Niger, Nigeria, whose drainage basin incorporates arid regions, receive a significant portion of their runoff from precipitation falling directly on the delta. Between 1970 and 2006, the Niger discharged (Lokoja station) 5000 ± 890 m3/s into upper delta. Here we apply Tropical Rainfall Measurement Mission (TRMM) based precipitation estimates (SB42), with a 0.25° x 0.25° spatial resolution (~100 grid points across the Niger Delta at 3 hourly intervals 1998-2008), and MODIS evapotranspiration (ET) estimates (MOD16), to determine the impact of massive local precipitation events on the routing of water and sediment flux through the Niger Delta's distributaries. The Niger delta receives 2275 mm/y ± 264 mm/y of rainfall with the SE area exceeding 3500 mm/y. The delta's ET varies seasonally between 45 and 65 mm/mo. The in situ generated hydrological runoff is 1675 mm/y, or an equivalent of a discharge 73% the size of the river flux entering the delta. With maximum annual daily discharge from the Niger often exceeding 15,000 m3/s, in combination with the significant in situ runoff, much of the delta's surface is seasonally under floodwaters. LandSat7 imagery indicates delta distributaries that are disconnected from the Niger River, and only drain local precipitation events. This disconnection plays into the discharge and sediment fluxes of these distributaries.

  2. The Riverbed Evolution, Avulsions and Backwater Hydrodynamics on the Huanghe River Delta

    NASA Astrophysics Data System (ADS)

    Chu, Z.; Ganti, V.; Lamb, M. P.

    2013-12-01

    The Huanghe River is known for high suspended sediment concentration and resultant heavy sedimentation and frequent channel-shifting among major rivers in the world. This plain coastal river is the main contributor of terrestrial sediment to the Bohai Sea and the Yellow Sea. Since 1855, there have been 11 major avulsions (versus 4 avulsions on the Mississippi River during the Holocene) on the lower reach with an recurrence interval of ~10 years, developing individual lobes that build up the modern Huanghe River delta. We summarize the main features of riverbed evolution on the delta with a database of measured data. The observed avulsions on the delta often occurred along a persistent spatial node, whose distance from the shoreline scales with the computed backwater length. In order to explain the avulsion locations on the delta, and meanwhile to test the viewpoint of river backwater controls on avulsion locations on deltas, we simulate the long profile evolution of the riverbed on the delta considering river discharge, river plume spreading, land subsidence and sea level rise, with a 1D fluvial morphodynamic model. The main results from the numerical simulations provide insights into how the long profile of the river on the delta evolves at the time scales of flood events and avulsions.

  3. 78 FR 39314 - Notice of Availability of the Decision Record for the Delta River Special Recreation Management...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-07-01

    ... Bureau of Land Management Notice of Availability of the Decision Record for the Delta River Special... the availability of the Decision Record (DR) for the Delta River Special Recreation Management Area... Assessment (EA) for the Delta River Special Recreation Management Area (SRMA) Plan and East Alaska...

  4. Reliability characteristics of a platform in the Mississippi River delta

    SciTech Connect

    Bea, R.G.

    1998-08-01

    In August 1995, the Energy Development Corporation installed a conventional drilling and production platform in South Pass Block 47. Due to its proximity to the delta of the Mississippi River, this platform is exposed to the environmental forces developed by hurricanes and movements of the seafloor. This paper summarizes results from probability-based study of the oceanographic, geotechnical, and structural reliability characteristics of a conventional platform installed in South Pass Block 47. Experience with other structures installed in this area that have failed due to seafloor slides is correlated with results from these analyses. The analyses indicated that a conventional platform could be safely installed at the proposed location. The platform has experienced several severe hurricanes without signs of distress.

  5. Microbial communities of alluvial soils in the Volga River delta

    NASA Astrophysics Data System (ADS)

    Sal'Nikova, N. A.; Polyanskaya, L. M.; Tyugai, Z. N.; Sal'Nikov, A. N.; Egorov, M. A.

    2009-01-01

    The number and biomass of the microbial community in the upper humus horizon (0-20 cm) were determined in the main types of alluvial soils (mucky gley, desertified soddy calcareous, hydrometamorphic dark-humus soils) in the Volga River delta. Fungal mycelium and alga cells predominate in the biomass of the microorganisms (35-50% and 30-47%, respectively). The proportion of prokaryotes in the microbial biomass of the alluvial soils amounts to 2-6%. No significant seasonal dynamics in the number and biomass of microorganisms were revealed in the alluvial soils. The share of carbon of the microbial biomass in the total carbon content of the soil organic matter is 1.4-2.3% in the spring. High coefficients of microbial mineralization and oligotrophy characterize the processes of organic matter decomposition in the alluvial soils of the mucky gley, desertified soddy calcareous, and hydrometamorphic dark humus soil types.

  6. Water management in the Senegal River Delta: a continuing uncertainty

    NASA Astrophysics Data System (ADS)

    Mietton, M.; Dumas, D.; Hamerlynck, O.; Kane, A.; Coly, A.; Duvail, S.; Pesneaud, F.; Baba, M. L. O.

    2007-11-01

    Water management is the driving force behind the productivity of the ecosystems of the Senegal River Estuary and floodplains. It is dependent on human decision-making, but has been separated from the River's flooding since the building of the Diama Dam. The current objectives of the Office de Mise en Valeur du fleuve Sénégal (OMVS: Senegal River Development Agency) are mainly turned towards the development of irrigated agriculture on the former floodplains and since 2002 the production of hydroelectric power at Manantali. In October 2003, a four-metre-wide runoff canal, which quickly widened into a breach several hundred metres across, was dug in the Barbary Spit area to protect the city of Saint-Louis from heavy flooding. The hydraulic quality of the area downstream from the dam has improved to the extent that there is no longer any flooding there, but as the management of the dams concerns only the section of the river between Manantali and Diama, a certain amount of flood risk probably still persists. The intrusion of seawater into the estuary is also threatening ecosystems and fresh water supplies, and abruptly altering agricultural practices such as fruit and vegetable growing in the Gandiolais district. When added to the tentative efforts to coordinate the management of the two dams, with no management objective downstream from Diama, such permanent modifications impose serious constraints on the managers and residents of the lower delta. This paper presents an overview of the constraints and uncertainties at different levels and scales. This wholly human-wrought environment can be considered as a learning experience, where a large number of variables need to be monitored closely and an ongoing process of participatory analysis should be backed up by multidisciplinary research.

  7. Assessing impact of urbanization on river water quality in the Pearl River Delta Economic Zone, China.

    PubMed

    Ouyang, Tingping; Zhu, Zhaoyu; Kuang, Yaoqiu

    2006-09-01

    The Pearl River Delta Economic Zone is one of the most developed regions in China. It has been undergoing a rapid urbanization since the reformation and opening of China in 1978. This process plays a significant impact on the urban environment, particularly river water quality. The main goal of this present study is to assess the impact of urban activities especially urbanization on river water quality for the study area. Some Landsat TM images from 2000 were used to map the areas for different pollution levels of urban river sections for the study area. In addition, an improved equalized synthetic pollution index method was utilized to assess the field analytical results. The results indicate that there is a positive correlation between the rapidity of urbanization and the pollution levels of urban river water. Compared to the rural river water, urban river water was polluted more seriously. During the urban development process, urbanization and urban activities had a significant negative impact on the river water quality.

  8. Natural and Human Impacts on Recent Development of Asian Large Rivers and Deltas

    NASA Astrophysics Data System (ADS)

    Liu, P.; Lu, C.

    2014-12-01

    Most recent data analysis indicates sediment loads in most of Asian large rivers (like, Yellow, Yangtze, Pearl, Chao Phraya, Indus, Krishna, Godavari, etc) have decreased up to 80-90% in the past 60 years. Correspondingly, most of Asian large river deltas are facing severe sediment starving; delta shoreline comparisons indicate that some are under strong coastal erosion. For examples, the Yellow River Delta has been retreating since 1990s when its annual sediment load has kept below 300 million tons. The Yangtze River delta kept growing before Three Gorges Dams was operating, and began to be eroded from the year 2003 to 2009, and then prograded locally due to the Deep Water Navigation Project. The Mekong Delta shoreline has also been dynamically changing with the sediment flux variation, eroding from 1989 to 1996 and prograding from 1996 to 2002. More information is available at http://www.meas.ncsu.edu/sealevel

  9. Integrating Delta Building Physics & Economics: Optimizing the Scale of Engineered Avulsions in the Mississippi River Delta

    NASA Astrophysics Data System (ADS)

    Kenney, M. A.; Mohrig, D.; Hobbs, B. F.; Parker, G.

    2011-12-01

    Land loss in the Mississippi River Delta caused by subsidence and erosion has resulted in habitat loss, interference with human activities, and increased exposure of New Orleans and other settled areas to storm surge risks. Prior to dam and levee building and oil and gas production in the 20th century, the long term rates of land building roughly balanced land loss through subsidence. Now, however, sediment is being deposited at dramatically lower rates in shallow areas in and adjacent to the Delta, with much of the remaining sediment borne by the Mississippi being lost to the deep areas of the Gulf of Mexico. A few projects have been built in order to divert sediment from the river to areas where land can be built, and many more are under consideration as part of State of Louisiana and Federal planning processes. Most are small scale, although there have been some proposals for large engineered avulsions that would divert a significant fraction of the remaining available sediment (W. Kim, et al. 2009, EOS). However, there is debate over whether small or large diversions are the economically optimally and socially most acceptable size of such land building projects. From an economic point of view, the optimal size involves tradeoffs between scale economies in civil work construction, the relationship between depth of diversion and sediment concentration in river water, effects on navigation, and possible diminishing returns to land building at a single location as the edge of built land progresses into deeper waters. Because land building efforts could potentially involve billions of dollars of investment, it is important to gain as much benefit as possible from those expenditures. We present the result of a general analysis of scale economies in land building from engineered avulsions. The analysis addresses the question: how many projects of what size should be built at what time in order to maximize the amount of land built by a particular time? The analysis

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

    NASA Astrophysics Data System (ADS)

    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

  11. The Potential of Time Series Based Earth Observation for the Monitoring of Large River Deltas

    NASA Astrophysics Data System (ADS)

    Kuenzer, C.; Leinenkugel, P.; Huth, J.; Ottinger, M.; Renaud, F.; Foufoula-Georgiou, E.; Vo Khac, T.; Trinh Thi, L.; Dech, S.; Koch, P.; Le Tissier, M.

    2015-12-01

    Although river deltas only contribute 5% to the overall land surface, nearly six hundred million people live in these complex social-ecological environments, which combine a variety of appealing locational advantages. In many countries deltas provide the major national contribution to agricultural and industrial production. At the same time these already very dynamic environments are exposed to a variety of threats, including the disturbance and replacement of valuable ecosystems, increasing water, soil, and air pollution, human induced land subsidence, sea level rise, as well upstream developments impacting water and sediment supplies. A constant monitoring of delta systems is thus of utmost relevance for understanding past and current land surface change and anticipating possible future developments. We present the potential of Earth Observation based analyses and derived novel information products that can play a key role in this context. Along with the current trend of opening up numerous satellite data archives go increasing capabilities to explore big data. Whereas in past decades remote sensing data were analysed based on the spectral-reflectance-defined 'finger print' of individual surfaces, we mainly exploit the 'temporal fingerprints' of our land surface in novel pathways of data analyses at differing spatial-, and temporally-dense scales. Following our results on an Earth Observation based characterization of large deltas globally, we present in depth results from the Mekong Delta in Vietnam, the Yellow River Delta in China, the Niger Delta in Nigeria, as well as additional deltas, focussing on the assessment of river delta flood and inundation dynamics, river delta coastline dynamics, delta morphology dynamics including the quantification of erosion and accretion processes, river delta land use change and trends, as well as the monitoring of compliance to environmental regulations.

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

    PubMed Central

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

    2016-01-01

    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. PMID:27386534

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

    PubMed

    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.

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

    PubMed

    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. PMID:27386534

  15. Barrier island arcs along abandoned Mississippi River deltas

    USGS Publications Warehouse

    Penland, S.; Suter, J.R.; Boyd, Ron

    1985-01-01

    Generation of transgressive barrier island arcs along the Mississippi River delta plain and preservation of barrier shoreline facies in their retreat paths on the inner shelf is controlled by: (1) shoreface translation; (2) age of the transgression; and (3) the thickness of the barrier island arc sediment package. Barrier island arcs experience an average relative sea level rise of 0.50-1.00 cm yr-1 and shoreface retreat rates range from 5-15 m yr-1. Young barrier island arc sediment packages (Isles Dernieres) are thin and have experienced limited landward retreat of the shoreface. Older barrier island arcs (Chandeleur Islands) are thicker and have experienced significant landward movement of the shoreface because of the greater time available for retreat. If the transgressed barrier shoreline sediment package lies above the advancing ravinement surface, the entire sequence is truncated. A thin reworked sand sheet marks the shoreface retreat path. The base of the transgressive sediment package can lie below the ravinement surface in older barrier shorelines. In this setting, the superstructure of the barrier shoreline is truncated, leaving the basal portion of the transgressive sequence preserved on the inner shelf. A variety of transgressive stratigraphic sequences from sand sheets to truncated barrier islands to sand-filled tidal inlet scars have been identified by high resolution seismic profiling across the shoreface retreat paths of Mississippi delta barrier island arcs. One of these examples, the Isles Dernieres, represents a recently detached barrier island arc in the early stages of transgression. An older example, the Chandeleur Islands, represents a barrier island arc experiencing long-term shoreface retreat. This paper describes the stratigraphic character and preserved transgressive facies for the Isles Dernieres and Chandeleur Islands. ?? 1985.

  16. The Selenga River delta - a geochemical barrier for the waters of Lake Baikal

    NASA Astrophysics Data System (ADS)

    Chalov, Sergey; Thorslund, Josefin; Pietron, Jan; Jarsjö, Jerker

    2016-04-01

    Delta systems play an important role in retention of sediments and contaminants to downstream recipients, through processes such as gravitational sedimentation, flocculation and biofiltration. The Selenga river delta is one of the world's largest inland deltas, providing a huge buffer zone between Lake Baikal and upstream waters of the Selenga river basin. Understanding the delta functioning is critical for the planning of water management measures in the Selenga River Basin and for protection of the waters of Lake Baikal. We here study the current state and functioning of the delta's ecosystem and hydrogeochemical processes. More specifically, we considered spatio-temporal changes in water flow, morphology and transport of sediments and metals within the delta and what potential impacts these changes may have on the delta functions. Results show that the delta network has a large influence on the mass of metals reaching the Lake Baikal at the delta outlet. Regions with high density of wetlands and small channels, in contrast to main channel regions, show a consistent pattern of considerable contaminant filtering and removal (between 77-99% for key metals), during both high and low flow conditions, following with a significant increase (2-3 times) of bottom sediment pollution. Geomorphological processes also governs the barrier function of the delta, due to partitioning of flow between different channel systems. These results are particularly relevant in the light of recent and expected future changes involving both the hydrology and water quality in the Lake Baikal basin. Taken together, this emphasizes the importance of understanding the interface between flow partitioning, delta morphology, and sediment and metal patterns and storage rates for fully capturing and quantifying the variety in delta functions. This is particularly relevant coupled to hydroclimatic changes in the region, which could lead to significant decline in barrier functions of the delta due to

  17. Plant community succession in modern Yellow River Delta, China*

    PubMed Central

    Zhang, Gao-sheng; Wang, Ren-qing; Song, Bai-min

    2007-01-01

    Data were collected in different successional stages using a simultaneous sampling method and analyzed through quantitative classification method. Three large groups and 12 classes were made to represent the community patterns of three succession stages and 12 succession communities. The succession series of plant community in the study area was as follows: saline bare land→community Suaeda salsa→community Tamarix chinensis→grassland. Succession degree and succession process of 12 succession communities were calculated. Most of these communities were in the lower succession stage, however, community Phragmites communis+Glycine soja and community Imperata cylindrica+G. soja were close to the succession stage of grassland climax. Five species diversity indices were used to study the changes in species richness, species evenness and diversity during succession of community. Heterogeneity index and richness index increased gradually during the community succession process, but species evenness tended to decrease with succession development. The relation between succession and environment was studied by ordination technique, and the results showed that the soil salt content was an important factor to halarch succession of the modern Yellow River Delta. It affected community structure, species composition and succession process. PMID:17657854

  18. Latest Quaternary stratigraphic framework of the Mississippi River delta region

    USGS Publications Warehouse

    Kulp, Mark; Howell, Paul; Adiau, Sandra; Penland, Shea; Kindinger, Jack; Williams, S. Jeffress

    2002-01-01

    Previous researchers separated the uppermost Quaternary stratigraphy of the Mississippi River delta region into two major lithofacies. The stratigraphically lower of these, "substratum," primarily consists of coarse-grained sediment deposited within lowstand-incised stream valleys. Relatively finer-grained "topstratum" overlies substratum; above interfluves, topstratum directly overlies weathered late Pleistocene sediments. However, the onshore to offshore distribution and architecture of these lithofacies was not well constrained. This study integrates published and unpublished lithostratigraphic data with high-resolution seismic profiles from the continental shelf to aid in mapping the regional distribution of major substratum deposits and thickness of topstratum sediments. A transgressive sand sheet commonly marks the base of the topstratum deposits, providing a stratigraphic marker to aid in regional lithostratigraphic correlations. Radiocarbondated deposits and boreholes tied to oxygen isotope chronologies provide chronostratigraphic control. Excellent correlation between these multiple datasets has been found to exist, enabling construction of regional isopachous and structural elevation maps and cross sections detailing elements of the Late Quaternary stratigraphy.

  19. [Numerical simulation study of SOA in Pearl River Delta region].

    PubMed

    Cheng, Yan-li; Li, Tian-tian; Bai, Yu-hua; Li, Jin-long; Liu, Zhao-rong; Wang, Xue-song

    2009-12-01

    Secondary organic aerosols (SOA) is an important component of the atmospheric particle pollution, thus, determining the status and sources of SOA pollution is the premise of deeply understanding the occurrence, development law and the influence factors of the atmospheric particle pollution. Based on the pollution sources and meteorological data of Pearl River Delta region, the study used the two-dimensional model coupled with SOA module to stimulate the status and source of SOA pollution in regional scale. The results show: the generation of SOA presents obvious characteristics of photochemical reaction, and the high concentration appears at about 14:00; SOA concentration is high in some areas of Guangshou and Dongguan with large pollution source-emission, and it is also high in some areas of Zhongshan, Zhuhai and Jiangmen which are at downwind position of Guangzhou and Dongguan. Contribution ratios of several main pollution sources to SOA are: biogenic sources 72.6%, mobile sources 30.7%, point sources 12%, solvent and oil paint sources 12%, surface sources less than 5% respectively. PMID:20187369

  20. Sediment and water chemistry of the San Juan River and Escalante River deltas of Lake Powell, Utah, 2010-2011

    USGS Publications Warehouse

    Hornewer, Nancy J.

    2014-01-01

    Recent studies have documented the presence of trace elements, organic compounds including polycyclic aromatic hydrocarbons, and radionuclides in sediment from the Colorado River delta and from sediment in some side canyons in Lake Powell, Utah and Arizona. The fate of many of these contaminants is of significant concern to the resource managers of the National Park Service Glen Canyon National Recreation Area because of potential health impacts to humans and aquatic and terrestrial species. In 2010, the U.S. Geological Survey began a sediment-core sampling and analysis program in the San Juan River and Escalante River deltas in Lake Powell, Utah, to help the National Park Service further document the presence or absence of contaminants in deltaic sediment. Three sediment cores were collected from the San Juan River delta in August 2010 and three sediment cores and an additional replicate core were collected from the Escalante River delta in September 2011. Sediment from the cores was subsampled and composited for analysis of major and trace elements. Fifty-five major and trace elements were analyzed in 116 subsamples and 7 composited samples for the San Juan River delta cores, and in 75 subsamples and 9 composited samples for the Escalante River delta cores. Six composited sediment samples from the San Juan River delta cores and eight from the Escalante River delta cores also were analyzed for 55 low-level organochlorine pesticides and polychlorinated biphenyls, 61 polycyclic aromatic hydrocarbon compounds, gross alpha and gross beta radionuclides, and sediment-particle size. Additionally, water samples were collected from the sediment-water interface overlying each of the three cores collected from the San Juan River and Escalante River deltas. Each water sample was analyzed for 57 major and trace elements. Most of the major and trace elements analyzed were detected at concentrations greater than reporting levels for the sediment-core subsamples and composited

  1. The sediment-starved Yellow River Delta as remotely controlled by human activities in the river basin

    NASA Astrophysics Data System (ADS)

    Wang, H.; Bi, N.

    2015-12-01

    Human presented significant disturbances on the natural processes of land-ocean interactions in context of global change. Here we illustrate how the signals of human activities in the river basin have been transferred to the coastal ocean along the hydrological pathway and remotely controlled the Yellow River Delta. Dam-orientated water and sediment regulation scheme (WSRS) has resulted in effective erosion of the lower channel and mitigation of siltation within the reservoirs. However, significant impacts have been identified on the delta morphology and coastal ecosystem ten years after the WSRS, which was unexpected at the beginning of engineering efforts. The coarser sediment derived from the channel erosion during the first phase of WSRS was directly contributed to the rapid accretion of present river mouth, whereas the delta was starved and declined due to insufficient sediment supply and regime shift of sediment transport. The fine-grained sediment exported from the Xiaolangdi Reservoir during the second phase of WSRS seemed to be a critical carrier for the nutrients and pollutants. The human-altered hydrological cycle, enhanced delivery of nutrient and pollutants and the changing estuarine environment present unpredictable impacts on both terrestrial and aquatic ecosystem in the delta region. These confirm that humans are modifying the river-coast system in ways that go well beyond climate change, and an integrated management of the river-coast continuum is crucially important for the sustainability of the river-delta system.

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

    NASA Astrophysics Data System (ADS)

    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.

  3. Morphology and Sediment Transport Dynamics of the Selenga River Delta, Lake Baikal, Russia

    NASA Astrophysics Data System (ADS)

    Dong, T. Y.; Il'icheva, L.; Nittrouer, J. A.; Pavolv, M.

    2013-12-01

    The Selenga River fan delta is a lacustrine system located in southeastern Siberia, Russia, where Selenga River flows into Lake Baikal. The Selenga River is the largest source of sediment and water entering Lake Baikal. Covering ~550 km2, the Selenga delta is one of the largest freshwater deltas in the world. Evaluating the Selenga delta and its morphology is very important for local residents who rely upon the delta for both ecological and agricultural welfare. However, a sediment budget remains poorly constrained, as do estimates for the partitioning of water and sediment amongst the numerous bifurcating delta channels. This information is critical for addressing how the delta morphology evolves and influences the stratigraphic composition of the delta. To investigate the morphological characteristics of the delta, a field expedition was undertaken during July 2013 in collaboration with Russian scientists. The overall goal of the field work was to constrain delta dynamics through data collection. Field measurements included single-beam bathymetry data and sidescan sonar data to characterize: 1) channel geometries of the delta; 2) bedform sizes and distribution; and 3) grain-size composition of the channel bed. Flow velocity measurements were collected within the bifurcating channels to measure water discharge. Bedload samples were obtained within the active distributary channels to measure downstream sediment fining. Additionally, channel island cores were collected in order to analyze the internal architecture of the delta. The data reveal a systematic downstream sediment fining, from a predominantly gravel bed near the delta apex, to a fine-sand bed at the delta-lake interface (~40 km total distance). Bathymetry data document how width-to-depth ratios systematically decrease downstream in association with increasing channel bifurcations and decreasing channel-bed grain size. Furthermore, the investigations reveal that the delta is actively terraced, with the

  4. Network topology, Transport dynamics, and Vulnerability Analysis in River Deltas: A Graph-Theoretic Approach

    NASA Astrophysics Data System (ADS)

    Tejedor, A.; Foufoula-Georgiou, E.; Longjas, A.; Zaliapin, I. V.

    2014-12-01

    River deltas are intricate landscapes with complex channel networks that self-organize to deliver water, sediment, and nutrients from the apex to the delta top and eventually to the coastal zone. The natural balance of material and energy fluxes which maintains a stable hydrologic, geomorphologic, and ecological state of a river delta, is often disrupted by external factors causing topological and dynamical changes in the delta structure and function. A formal quantitative framework for studying river delta topology and transport dynamics and their response to change is lacking. Here we present such a framework based on spectral graph theory and demonstrate its value in quantifying the complexity of the delta network topology, computing its steady state fluxes, and identifying upstream (contributing) and downstream (nourishment) areas from any point in the network. We use this framework to construct vulnerability maps that quantify the relative change of sediment and water delivery to the shoreline outlets in response to possible perturbations in hundreds of upstream links. This enables us to evaluate which links (hotspots) and what management scenarios would most influence flux delivery to the outlets, paving the way of systematically examining how local or spatially distributed delta interventions can be studied within a systems approach for delta sustainability.

  5. Morphologic and stratigraphic evolution of muddy ebb-tidal deltas along a subsiding coast: Barataria Bay, Mississippi River delta

    USGS Publications Warehouse

    FitzGerald, D.M.; Kulp, M.; Penland, S.; Flocks, J.; Kindinger, J.

    2004-01-01

    The Barataria barrier coast formed between two major distributaries of the Mississippi River delta: the Plaquemines deltaic headland to the east and the Lafourche deltaic headland to the west. Rapid relative sea-level rise (1??03 cm year-1) and other erosional processes within Barataria Bay have led to substantial increases in the area of open water (> 775 km2 since 1956) and the attendant bay tidal prism. Historically, the increase in tidal discharge at inlets has produced larger channel cross-sections and prograding ebb-tidal deltas. For example, the ebb delta at Barataria Pass has built seaward > 2??2 km since the 1880s. Shoreline erosion and an increasing bay tidal prism also facilitated the formation of new inlets. Four major lithofacies characterize the Barataria coast ebb-tidal deltas and associated sedimentary environments. These include a proximal delta facies composed of massive to laminated, fine grey-brown to pale yellow sand and a distal delta facies consisting of thinly laminated, grey to pale yellow sand and silty sand with mud layers. The higher energy proximal delta deposits contain a greater percentage of sand (75-100%) compared with the distal delta sediments (60-80%). Associated sedimentary units include a nearshore facies consisting of horizontally laminated, fine to very fine grey sand with mud layers and an offshore facies that is composed of grey to dark grey, laminated sandy silt to silty clay. All facies coarsen upwards except the offshore facies, which fines upwards. An evolutionary model is presented for the stratigraphic development of the ebb-tidal deltas in a regime of increasing tidal energy resulting from coastal land loss and tidal prism growth. Ebb-tidal delta facies prograde over nearshore sediments, which interfinger with offshore facies. The seaward decrease in tidal current velocity of the ebb discharge produces a gradational contact between proximal and distal tidal delta facies. As the tidal discharge increases and the inlet

  6. Numerical investigation of surface water-groundwater interactions in a river-dominated delta

    NASA Astrophysics Data System (ADS)

    Sawyer, Audrey; Edmonds, Douglas; Knights, Deon

    2015-04-01

    Deltas are fragile coastal wetland systems that are rapidly vanishing due to subsidence and sea level rise. In most wetland environments, groundwater plays a central role in carbon and nutrient cycles, vegetation community structure, and contaminant transport, yet little is known about groundwater in vanishing delta wetlands. Here, we characterize the basic patterns, rates, and residence times of groundwater flow in a model delta wetland. Delta topography was simulated by growing the delta in Delft3D, a morphodynamic flow and sediment transport model. Water surface elevations under mean annual discharge conditions were used to drive a steady groundwater flow model. Under these average hydrologic conditions, surface water-groundwater exchange represents a small fraction (<1%) of river discharge to the coast, but storm surge, waves, and tides likely increase exchange rates periodically. Groundwater residence times range widely from hours to years. The residence time distribution exhibits power-law tailing that is characteristic of surface water-groundwater exchange in single-threaded river channels. The patterns of groundwater residence times within delta networks are likely to control redox chemistry and may therefore influence the community structure of microbes, benthic invertebrates, and plants. This study illustrates the tremendous potential for numerical approaches to characterizing groundwater flow in delta wetlands. Continued efforts are needed to understand the role of groundwater in delta wetlands, particularly in light of growing initiatives to restore deltas and their ecosystems.

  7. [Community structure of planktonic rotifers in the Pearl River Delta].

    PubMed

    Gao, Yuan; Li, Xin-Hui; Lai, Zi-Ni; Yu, Jing; Wang, Chao; Zeng, Yan-Yi; Liu, Qian-Fu; Yang, Wan-Ling

    2014-07-01

    Four ecological investigations were carried out on planktonic rotifers in Pearl River Delta in 2012. The community structure, including spatial and temporal patterns of species composition, dominant species, biomass and biodiversity, was investigated. The correlation between the community structure of rotifers and the environmental factors was discussed. Moreover, the aggregation structures of rotifers were analyzed. A total of 53 rotifer species were found. Dominant species changed markedly with season and space. Polyarthra trigla had higher dominance. In terms of seasonal changes, the density and biomass were higher in dry season than in wet season, while the biodiversity and evenness indices were vice versa. The biomass and biodiversity of rotifers showed highly significant differences among seasons. In terms of spatial distribution, the average density and the average biomass showed an increase from the southwest to the northeast. The highest density and biomass were recorded in Shiqiao. The biodiversity and evenness indices had an opposite spatial distribution, with the highest values being recorded in Qingqi. The rotifer density was significantly different among the investigated sites, while the biomass and biodiversity were not significantly different. Correlation analysis demonstrated a highly significant positive correlation between rotifer density and biomass, as well as between biodiversity and evenness indices, and a highly negative correlation between biodiversity and biomass. The biodiversity and evenness indices both decreased markedly with the increase of biomass. Principal component analysis indicated that the rotifer density was closely correlated with environment factors, such as water temperature, pH, dissolved oxy- gen, chlorophyll a content, total phosphorus, and total nitrogen, in different seasons. Aggregation analysis based on rotifer density revealed five aggregation structures in the investigated sites, indicating significant differences

  8. Recent morphodynamic evolution of coastline of Mekong river Delta, towards an increased vulnerability

    NASA Astrophysics Data System (ADS)

    Besset, Manon; Brunier, Guillaume; Anthony, Edward

    2015-04-01

    Key words: Mekong river delta - Coastal deltaic morphodynamic - Deltaic vulnerability The complexity of coastal river deltas lies in part in aspects of sediment supply and redistribution, trapping and readjustment. The sediment supply and involved processes are governed by river-marine forcing, weather and climate, increasingly affected by humans, all within a frame of interactivity and morphodynamic equilibrium/disequilibrium that determine the evolution of the delta. The Mekong river delta is the third largest delta in the world. It is subject to important tidal influence, alluvial contribution from the fourth largest Asian river, seasonal monsoons and associated swell and other high-energy events. After a strong advance of over 200 km from 6.0 ka to near present (Tamura et al., 2012), the delta shoreline is rapidly and irregularly retreating, constraining the 20 million people living off the delta to suffer or adapt. This study documents changes over the last 50 years affecting the 700 km-long shoreline of the delta based on analysis of USGS topographic maps (1965), low-resolution Landsat (1973-2014) and very high-resolution SPOT 5 (2003-2011) satellite imagery. The results show widespread erosion of nearly 10 m/year over the period corresponding to the Second Indochinese conflict (1962-1972). Then followed a multi-decadal phase of accretion of about 8 m/yr, with spatial fluctuations of up to nearly -20 m/yr. This variability could reflect alternation of periods of resilience and self-organization in coastal sediment cells. A deceleration of accretion in the 2000s (+0.63 m/yr) and even a shift to erosion since 2011 (-1 m/s) are observed in parallel with the intensification of land-use changes, exploitation of the river-bed by sand mining, and hydropower dams (Brunier et al., 2014), and deforestation of deltaic wetlands for agriculture and fisheries(Thu et al., 2007). These erosion trends and their spatiotemporal disparities exacerbate the vulnerability of the

  9. Sand as a stable and sustainable resource for nourishing the Mississippi River delta

    NASA Astrophysics Data System (ADS)

    Nittrouer, Jeffrey A.; Viparelli, Enrica

    2014-05-01

    The Mississippi River delta is undergoing a catastrophic drowning, whereby 5,000 km2 of low-lying wetlands have converted to open water over at least the past eight decades, as a result of many anthropogenic and natural factors. Continued net land loss has been thought inevitable due to a decline in the load of total suspended sediment--both sand and mud--carried by the river. However, sand--which accounts for ~50-70% of modern and ancient Mississippi delta deposits but comprises only ~20% of the sampled portion of the total load--could be more important than mud for subaerial delta growth. Historically, half of the Mississippi River sediment load is supplied by the Missouri River. Here we analyse suspended sediment load data from two locations downstream from the lowest Missouri River dam to show that the measured sand load in the lower 1,100 km of the Mississippi River has not significantly diminished since dam construction. A one-dimensional numerical model of river morphodynamics predicts that the sand load feeding the delta will decrease only gradually over the next several centuries, with an estimated decline from current values of no more than about 17% within the coming six centuries. We conclude that the lower Mississippi River channel holds a significant reservoir of sand that is available to replenish diminished loads via bed scour and substantially mitigate land loss.

  10. Establishing river basin organisations inVietnam: Red River, Dong Nai River and Lower Mekong Delta.

    PubMed

    Taylor, P; Wright, G

    2001-01-01

    River basin management is receiving considerable attention at present. Part of the debate, now occurring worldwide, concerns the nature of the organisations that are required to manage river basins successfully, and whether special-purpose river basin organisations (RBOs) are always necessary and in what circumstance they are likely to (i) add to the management of the water resources and (ii) be successful. The development of river basin management requires a number of important elements to be developed to a point where the river basin can be managed successfully. These include the relevant laws, the public and non-government institutions, the technical capabilities of the people, the understanding and motivation of people, and the technical capacity and systems, including information. A river basin organisation (or RBO) is taken to mean a special-purpose organisation charged with some part of the management of the water resources of a particular river basin. Generally speaking, such organisations are responsible for various functions related to the supply, distribution, protection and allocation of water, and their boundaries follow the watershed of the river in question. However, the same functions can be carried out by various organisations, which are not configured on the geographical boundaries of a river basin. This paper outlines recent work on river basin organisation in Vietnam, and makes some comparisons with the situation in Australia.

  11. Grain size controls on the morphology and stratigraphy of river-dominated deltas

    NASA Astrophysics Data System (ADS)

    Burpee, Alex; Parsons, Daniel; Slingerland, Rudy; Edmonds, Doug; Best, Jim; Cederberg, James; McGuffin, Andrew; Caldwell, Rebecca; Nijhuis, Austin

    2015-04-01

    The proportions of sand and mud that make up a river-dominated delta strongly determine its topset morphology, which in turn controls its internal facies and clinoform geometry. These relationships allow prediction of the stratigraphy of a delta using the character of its topset and reconstruction of deltaic planform from measures of clinoform geometry. This paper presents results from the Delft3D modeling system which was used to simulate nine self-formed deltas that possess different sediment loads and critical shear stresses that are required for re-entrainment of mud. The simulated deltas were set to prograde into a shallow basin without waves, tides, Coriolis forcing, and buoyancy. Model results indicate that sand-dominated deltas are more fan-shaped whilst mud-dominated deltas are more birdsfoot in planform, because the sand-dominated deltas have more active distributaries, a smaller variance of topset elevations, and thereby experience a more equitable distribution of sediment to their perimeters. This results in a larger proportion of channel facies in sand-dominated deltas, and more uniformly-distributed clinoform dip directions, steeper dips, and greater clinoform concavity. These conclusions are consistent with data collected from the Goose River Delta, a coarse-grained fan delta prograding into Goose Bay, Labrador, Canada and also allow us to undertake a re-interpretation of the Kf-1 parasequence set of the Cretaceous Last Chance Delta, a unit of the Ferron Sandstone near Emery, Utah, USA. We argue that the Last Chance delta likely possessed numerous distributaries with at least five orders of bifurcation.

  12. Mercury in the Mackenzie River delta and estuary: concentrations and fluxes during open-water conditions.

    PubMed

    Graydon, Jennifer A; Emmerton, Craig A; Lesack, Lance F W; Kelly, Erin N

    2009-04-01

    Estimates of mercury (Hg) loadings to the Arctic Ocean from circumpolar rivers have not considered biogeochemical changes that occur when river water is temporarily stored in large deltas (delta effect). There are also few data describing Hg changes across the freshwater-saltwater transition zone (FSTZ) of these rivers. We assessed temporal changes in unfiltered total mercury (THg) and methylmercury (MeHg) concentrations during open-water 2004 in the Mackenzie River upstream of the Mackenzie River delta, and in 6 floodplain lakes across an elevation gradient. These data were used to calculate Hg fluxes from the Mackenzie River and to evaluate a delta effect on Hg using an estimate of delta river water storage and a mixing analysis. Mean THg concentrations were highest in river water (9.17+/-5.51 ng/L) and decreased up the lake elevation gradient. Mean MeHg concentrations were highest in lakes periodically connected to the river (0.213+/-0.122 ng/L) and MeHg concentrations in elevated lakes showed a mid-summer peak. Results from the mixing analysis showed that the delta effect may be large enough to affect Hg loadings to the Arctic Ocean. THg concentrations exiting the delta (10.2 ng/L) were 16% lower than those entering (12.1 ng/L), whereas MeHg showed little change. We calculated 2.5-month (open-water) THg and MeHg fluxes from the Mackenzie River of 1208 and 8.4 kg. These fluxes are similar in magnitude to previous annual estimates in the arctic literature suggesting that previously published annual Hg fluxes from the Mackenzie River may be large underestimates. We also assessed changes in Mackenzie River water THg and MeHg concentrations as it crossed the FSTZ during an open-water cruise. THg decreased non-conservatively across the estuary from 3.8-0.6 ng/L, possibly due to mixing and particle settling. MeHg concentrations were variable and near detection. Our results show that the Mackenzie River estuary is a dynamic environment and may have important controls

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

    PubMed

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

    2015-01-01

    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. PMID:26446752

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

    PubMed

    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.

  15. Sediment transport dynamics linked to morphological evolution of the Selenga River delta, Lake Baikal, Russia

    NASA Astrophysics Data System (ADS)

    Dong, T. Y.; Nittrouer, J.; McElroy, B. J.; Czapiga, M. J.; Il'icheva, E.; Pavolv, M.; Parker, G.

    2014-12-01

    The Selenga River delta, Lake Baikal, Russia, is approximately 700 km2 in size and contains three active lobes that receive varying amounts of water and sediment discharge. This delta represents a unique end-member in so far that the system is positioned along the deep-water (~1500 m) margin of Lake Baikal and therefore exists as a shelf-edge delta. In order to evaluate the morphological dynamics of the Selenga delta, field expeditions were undertaken during July 2013 and 2014, to investigate the morphologic, sedimentologic, and hydraulic nature of this delta system. Single-beam bathymetry data, sidescan sonar data, sediment samples, and aerial survey data were collected and analyzed to constrain: 1) channel geometries within the delta, 2) bedform sizes and spatial distributions, 3) grain size composition of channel bed sediment as well as bank sediment, collected from both major and minor distributary channels, and 4) elevation range of the subaerial portion of the delta. Our data indicate that the delta possesses downstream sediment fining, ranging from predominantly gravel and sand near the delta apex to silt and sand at the delta-lake interface. Field surveys also indicate that the Selenga delta has both eroding and aggrading banks, and that the delta is actively incising into some banks that consist of terraces, which are defined as regions that are not inundated by typical 2- to 4-year flood discharge events. Therefore the terraces are distinct from the actively accreting regions of the delta that receive sedimentation via water inundation during regular river floods. We spatially constrain the regions of the Selenga delta that are inundated during floods versus terraced using a 1-D water-surface hydrodynamic model that produces estimates of stage for flood water discharges, whereby local water surface elevations produced with the model are compared to the measured terrestrial elevations. Our analyses show that terrace elevations steadily decrease downstream

  16. Quantifying the signature of sediment composition on the topologic and dynamic complexity of river delta channel networks and inferences toward delta classification

    NASA Astrophysics Data System (ADS)

    Tejedor, Alejandro; Longjas, Anthony; Caldwell, Rebecca; Edmonds, Douglas A.; Zaliapin, Ilya; Foufoula-Georgiou, Efi

    2016-04-01

    Deltas contain complex self-organizing channel networks that nourish the surface with sediment and nutrients. Developing a quantitative understanding of how controlling physical mechanisms of delta formation relate to the channel networks they imprint on the landscape remains an open problem, hindering further progress on quantitative delta classification and understanding process from form. Here we isolate the effect of sediment composition on network structure by analyzing Delft3D river-dominated deltas within the recently introduced graph-theoretic framework for quantifying complexity of delta channel networks. We demonstrate that deltas with coarser incoming sediment tend to be more complex topologically (increased number of pathways) but simpler dynamically (reduced flux exchange between subnetworks) and that once a morphodynamic steady state is reached, complexity also achieves a steady state. By positioning simulated deltas on the so-called TopoDynamic complexity space and comparing with field deltas, we propose a quantitative framework for exploring complexity toward systematic inference and classification.

  17. Cyclone Nargis survey in Myanmar's Ayeyarwady River delta

    NASA Astrophysics Data System (ADS)

    Fritz, H. M.; Blount, C.; Thwin, S.; Thu, M. K.; Chan, N.

    2008-12-01

    Tropical cyclone Nargis (Cat. 4) made landfall on May 2, 2008, causing the worst natural disaster in Myanmar's recorded history. Official death toll estimates exceed 130,000 fatalities making it the 7th deadliest cyclone ever recorded worldwide. Nargis took a rare nearly eastern track over the Bay of Bengal while developing sustained winds over 210 km/h with gusts up to 260 km/h hours prior to landfall in Myanmar at untypically low latitude near 16°N. It then proceeded northeast and approximately 12 hours later weakened to a Category 1 storm with sustained wind speeds of 130 km/h as it passed over Yangon. The first independent storm surge reconnaissance team was deployed to Myanmar from 9 to 23 August 2008. Cyclone Nargis struck low-lying coastal plains particularly vulnerable to storm surge flooding due to the lack of effective barriers. The team surveyed coastal and inland villages from Pyapon to Purian Point, encompassing the Bogale and Ayeyarwady River mouths. The survey by boat spanned more than 150 km parallel to the cyclone track between Pyapon and Pyinkhayan encompassing 20 hardest hit settlements such as Pyinsalu. More than 1m vertical erosion and 150 m land loss were measured at various coastal locations such as Aya. Massive deforestation of mangroves and land use were documented. Maximum storm surge elevations and overland flow depths were measured based on water marks on buildings, scars on trees, and rafted debris. The storm surge peaked in the landfall area south of Pyinkhayan and eastwards in Pyinsalu exceeding 5m. Storm waves more than 2m high were superimposed on the storm surge level in most areas according to eyewitnesses. Inundation distances reached beyond 50 km inland. Catastrophic peak fatality rates exceeded 80% in hardest hit villages with the majority being children and women. The high water marks and fatality rates significantly exceeded corresponding 2004 Indian Ocean tsunami values at every location. Eyewitnesses were interviewed to

  18. EAARL Coastal Topography-Pearl River Delta 2008: First Surface

    USGS Publications Warehouse

    Nayegandhi, Amar; Brock, John C.; Wright, C. Wayne; Miner, Michael D.; Michael, D.; Yates, Xan; Bonisteel, Jamie M.

    2009-01-01

    These remotely sensed, geographically referenced elevation measurements of Lidar-derived first surface (FS) topography were produced as a collaborative effort between the U.S. Geological Survey (USGS), Florida Integrated Science Center (FISC), St. Petersburg, FL; the University of New Orleans (UNO), Pontchartrain Institute for Environmental Sciences (PIES), New Orleans, LA; and the National Aeronautics and Space Administration (NASA), Wallops Flight Facility, VA. This project provides highly detailed and accurate datasets of a portion of the Pearl River Delta in Louisiana and Mississippi, acquired March 9-11, 2008. The datasets are made available for use as a management tool to research scientists and natural resource managers. An innovative airborne Lidar instrument originally developed at the NASA Wallops Flight Facility, and known as the Experimental Advanced Airborne Research Lidar (EAARL), was used during data acquisition. The EAARL system is a raster-scanning, waveform-resolving, green-wavelength (532-nanometer) Lidar designed to map near-shore bathymetry, topography, and vegetation structure simultaneously. The EAARL sensor suite includes the raster-scanning, water-penetrating full-waveform adaptive Lidar, a down-looking red-green-blue (RGB) digital camera, a high-resolution multi-spectral color infrared (CIR) camera, two precision dual-frequency kinematic carrier-phase GPS receivers, and an integrated miniature digital inertial measurement unit, which provide for submeter georeferencing of each laser sample. The nominal EAARL platform is a twin-engine Cessna 310 aircraft, but the instrument may be deployed on a range of light aircraft. A single pilot, a Lidar operator, and a data analyst constitute the crew for most survey operations. This sensor has the potential to make significant contributions in measuring sub-aerial and submarine coastal topography within cross-environmental surveys. Elevation measurements were collected over the survey area using the

  19. EAARL Coastal Topography-Pearl River Delta 2008: Bare Earth

    USGS Publications Warehouse

    Nayegandhi, Amar; Brock, John C.; Wright, C. Wayne; Miner, Michael D.; Yates, Xan; Bonisteel, Jamie M.

    2009-01-01

    These remotely sensed, geographically referenced elevation measurements of Lidar-derived bare earth (BE) topography were produced as a collaborative effort between the U.S. Geological Survey (USGS), Florida Integrated Science Center (FISC), St. Petersburg, FL; the University of New Orleans (UNO), Pontchartrain Institute for Environmental Sciences (PIES), New Orleans, LA; and the National Aeronautics and Space Administration (NASA), Wallops Flight Facility, VA. This project provides highly detailed and accurate datasets of a portion of the Pearl River Delta in Louisiana and Mississippi, acquired March 9-11, 2008. The datasets are made available for use as a management tool to research scientists and natural resource managers. An innovative airborne Lidar instrument originally developed at the NASA Wallops Flight Facility, and known as the Experimental Advanced Airborne Research Lidar (EAARL), was used during data acquisition. The EAARL system is a raster-scanning, waveform-resolving, green-wavelength (532-nanometer) Lidar designed to map near-shore bathymetry, topography, and vegetation structure simultaneously. The EAARL sensor suite includes the raster-scanning, water-penetrating full-waveform adaptive Lidar, a down-looking red-green-blue (RGB) digital camera, a high-resolution multi-spectral color infrared (CIR) camera, two precision dual-frequency kinematic carrier-phase GPS receivers, and an integrated miniature digital inertial measurement unit, which provide for submeter georeferencing of each laser sample. The nominal EAARL platform is a twin-engine Cessna 310 aircraft, but the instrument may be deployed on a range of light aircraft. A single pilot, a Lidar operator, and a data analyst constitute the crew for most survey operations. This sensor has the potential to make significant contributions in measuring sub-aerial and submarine coastal topography within cross-environmental surveys. Elevation measurements were collected over the survey area using the

  20. Subaquatic soils in the Volga, Don and Kuban Rivers deltas.

    NASA Astrophysics Data System (ADS)

    Tkachenko, Anna; Gerasimova, Maria; Lychagin, Mikhail

    2015-04-01

    River deltas occupy a special interface position in the environment and are characterized by contrasting hydrological and landscape-geochemical regimes. Small depth of water and weak currents contribute to suspended matter deposition. Significant spread of aquatic plants provides the enrichment of subaquatic soils in organic matter. All these factors contribute to the formation of different subaquatic soils. Possibility of including them in the classification systems is discussed by many authors (Demas and Rabenhorst, 2001; Stolt et al., 2011); there is also a special subaquatic qualifier for submerged soils in WRB; however, they are still absent in many national classification systems, as well as in the recent Russian one (2008). The purpose of this research is to reveal the properties of the subaquatic soils in the Volga, Don and Kuban Rivers deltaic areas and to propose pedogenetic approaches to categorize AQUAZEMS. Investigations of deltaic areas were performed in 2010-2012 in deltaic lagoons, fresh-water bays, small channels, oxbow lakes, and also in the part of deltaic near-shore zone. Morphological descriptions of distinguishable layers (colour, texture, thickness, boundaries, consistence, plant residues and shell debris) were made in columns obtained by augering as it is done by other researchers (Stolt et al., 2011), and supplemented with analytical data (pH, Eh, TDS, particle-size composition, and Corg). It is suggested to name the horizons in aquazems in the same way as in terrestrial soils in the recent Russian soil classification system, and apply symbols starting with the combination of caps - AQ. Most typical for aquazems is their aquagley AQG horizon that has features similar to terrestrial gleys - homogeneity in color and consistence, permeation by clay, predominance of dove grey colour. The AQG horizon gradually merges into parent material - stratified bottom sediments. The "topsoil" is usually enriched in organic matter and may be different in

  1. A graph-theoretic approach to River Deltas: Studying complexity, universality, and vulnerability to change.

    NASA Astrophysics Data System (ADS)

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

    2015-04-01

    River deltas are landforms with complex channel networks that deliver water, sediment and nutrient fluxes from rivers to oceans or inland water bodies via multiple pathways. Most of the deltas are subject to anthropogenic and natural perturbations causing topological and dynamical changes in the delta structure and function. We present a quantitative framework based on spectral graph theory within which a systematic study of the topology, transport dynamics and response to change of river deltas can be performed, as well as computation of sub-networks (from apex to shoreline outlets), and contributing/nourishing areas. We introduce metrics of topologic and dynamic complexity and define a multidimensional complexity space where each delta projects. By analysis of seven deltas of different morphodynamic and environmental settings, we report a surprising power law relationship between sub-network size and its dynamic exchange with surrounding sub-networks within the deltaic system. The exponent of the relationship is universal (predicting that a sub-network twice as large leaks out to other sub-networks only 1.3 times its total flux) and the pre-exponent depends on the topologic complexity of the delta network as a whole, i.e., the ensemble of the interacting sub-sub-networks. We also use the developed framework to construct vulnerability maps that quantify the relative change of sediment and water delivery to the shoreline outlets in response to possible perturbations in hundreds of upstream links. This enables us to evaluate which links (hotspots) and what management scenarios would most influence flux delivery to the outlets, paving the way for systematically examining how local or spatially distributed delta interventions can be studied within a systems approach for delta sustainability.

  2. River delta network hydraulic residence time distributions and their role in coastal nutrient biogeochemistry

    NASA Astrophysics Data System (ADS)

    Hiatt, M. R.; Castaneda, E.; Twilley, R.; Hodges, B. R.; Passalacqua, P.

    2015-12-01

    River deltas have the potential to mitigate increased nutrient loading to coastal waters by acting as biofilters that reduce the impact of nutrient enrichment on downstream ecosystems. Hydraulic residence time (HRT) is known to be a major control on biogeochemical processes and deltaic floodplains are hypothesized to have relatively long HRTs. Hydrological connectivity and delta floodplain inundation induced by riverine forces, tides, and winds likely alter surface water flow patterns and HRTs. Since deltaic floodplains are important elements of delta networks and receive significant fluxes of water, sediment, and nutrients from distributary channels, biogeochemical transformations occurring within these zones could significantly reduce nutrient loading to coastal receiving waters. However, network-scale estimates of HRT in river deltas are lacking and little is known about the effects of tides, wind, and the riverine input on the HRT distribution. Subsequently, there lacks a benchmark for evaluating the impact of engineered river diversions on coastal nutrient ecology. In this study, we estimate the HRT of a coastal river delta by using hydrodynamic modeling supported by field data and relate the HRT to spatial and temporal patterns in nitrate levels measured at discrete stations inside a delta island at Wax Lake Delta. We highlight the control of the degree of hydrological connectivity between distributary channels and interdistributary islands on the network HRT distribution and address the roles of tides and wind on altering the shape of the distribution. We compare the observed nitrate concentrations to patterns of channel-floodplain hydrological connectivity and find this connectivity to play a significant role in the nutrient removal. Our results provide insight into the potential role of deltaic wetlands in reducing the nutrient loading to near-shore waters in response to large-scale river diversions.

  3. Nile Delta

    Atmospheric Science Data Center

    2013-04-15

    article title:  The Nile River Delta     View Larger Image ... of eastern Africa. At the apex of the fertile Nile River Delta is the Egyptian capital city of Cairo. To the west are the Great Pyramids ...

  4. A river mouth submarine channel and failure complex, Fraser Delta, Canada

    NASA Astrophysics Data System (ADS)

    Hart, B. S.; Prior, D. B.; Barrie, J. V.; Currie, R. G.; Luternauer, J. L.

    1992-11-01

    High-resolution seismic and side-scan sonar surveying, combined with coring, of the Fraser Delta slope seaward of the main fluvial distributary has revealed a complex suite of morphologic units which include undisturbed delta slope sediments, shallow rotational slides, relict and active slope channels, debris accumulations and ponded turbidites. Sediment transport through the main submarine channel is thought to be primarily by debris flows, rather than by turbidity currents. Although this is a seismically active region, the instability related features described here are probably due primarily to rapid sediment deposition on the upper delta slope at the river mouth.

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

    NASA Astrophysics Data System (ADS)

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

    2015-10-01

    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.

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

    PubMed Central

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

    2015-01-01

    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. PMID:26446752

  7. Birds of the Indigirka River Delta, Russia: Historical and biogeographic comparisons

    USGS Publications Warehouse

    Pearce, J.M.; Esler, Daniel; Degtyarev, A.G.

    1998-01-01

    We documented the breeding status and relative abundance of all avian species on the coastal portion of the Indigirka River Delta during spring and summer 1993-95. Data on avifaunal composition were then compared to data from adjacent areas from Eastern Siberia to the Chukotka Peninsula to evaluate how species composition changes longitudinally within the arctic and typical tundra zones of northern Russia. We recorded 63 species on the Indigirka River Delta, 37 (58.7 %) of which were confirmed breeders during at least one of the three years. Five new species were recorded breeding (Arenaria interpres, Calidris acuminata, Limnodromus scolopaceus, Stercorarius parasiticus, and Asio flammeus), and 13 previously unrecorded species were observed during this study. We also identified several species of rare or threatened status in Russia and North America, including Branta bernicla, Somateria fischeri, Polysticta stelleri, and Rhodostethia rosea. We used parsimony and distance matrix methods to compare the breeding species richness on the Indigirka River Delta to that of six other Russian Arctic areas. Biogeographic comparisons revealed the presence of two clades in the Russian Arctic: the Lena River Delta east to Chaun Delta and the Chukotka Peninsula.

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

    NASA Astrophysics Data System (ADS)

    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

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

    USGS Publications Warehouse

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

    2005-01-01

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

  10. Geoarcheological investigations on the development of the Neva River delta (Gulf of Finland) during the Holocene

    NASA Astrophysics Data System (ADS)

    Kulkova, M. A.; Gusentsova, T. M.; Sapelko, T. V.; Nesterov, E. M.; Sorokin, P. E.; Ludikova, A. V.; Ryabchuk, D. V.; Markova, M. A.

    2014-01-01

    The article is devoted to the formation of the Neva River in the context of geoarcheological investigations carried out on the archeological site Okhta 1, which is located at the mouth of the Okhta River in the St. Petersburg city region (NW Russia). The site is multilayered and includes cultural layers from the Neolithic, Early Metal Age, Iron Age, and the Landskrona 13th century and Nienschanz 17th century fortresses. The Neva River's formation has long been a controversial question. The transgression of Ladoga Lake around 5950-2950 cal BP had an effect on the formation of the Neva River. By reviewing the complex investigations of the deposits and artifacts by geological and archeological methods, we may reconstruct the developmental stages of the Litorina Sea Bay and Neva River delta in this area. The formation of delta river sediments occurred from 3589 to 3078 cal BP. The end of the delta river formation can be associated with the appearance of ancient Early Iron Age people in the region in 2750-2350 cal BP.

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

    USGS Publications Warehouse

    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

  12. STS-65 Earth observation of Omo River Delta, Lake Turkana in Ethiopia / Kenya

    NASA Technical Reports Server (NTRS)

    1994-01-01

    STS-65 Earth observation taken aboard Columbia, Orbiter Vehicle (OV) 102, is of Omo River Delta and Lake Turkana in Ethiopia / Kenya. The Omo Delta at the north end of Lake Turkana (Rudolph) is one of the long-term environmental study sites of the Space Shuttle program. The environmental interest in this instance is the documentation of the delta's extension into the lake. This delta extension, or aggradation, is felt to be the result of large-scale soil erosion in the recently deforested areas of Ethiopia in the watershed of the Omo River. Using digitized, rectified, machine-classified, and mensurated NASA photography, it has been determined that the Omo Delta has increased in area by approximately 400% to about 1,800 square kilometers since it was first photographed during the Gemini program in 1965. This photograph documents the long-term and increasing turbidity of Lake Turkana and the continuing delta extension southward by both the northwest and northeast distributaries of the Om

  13. HABITAT ASSESSMENT USING A RANDOM PROBABILITY BASED SAMPLING DESIGN: ESCAMBIA RIVER DELTA, FLORIDA

    EPA Science Inventory

    Smith, Lisa M., Darrin D. Dantin and Steve Jordan. In press. Habitat Assessment Using a Random Probability Based Sampling Design: Escambia River Delta, Florida (Abstract). To be presented at the SWS/GERS Fall Joint Society Meeting: Communication and Collaboration: Coastal Systems...

  14. Dead delta's former productivity: Two trillion shells at the mouth of the Colorado River

    NASA Astrophysics Data System (ADS)

    Kowalewski, Michal; Avila Serrano, Guillermo E.; Flessa, Karl W.; Goodfriend, Glenn A.

    2000-12-01

    The diversion of the Colorado River by dams and irrigation projects, started in the 1930s, triggered the collapse of the Colorado delta ecosystem. Paleontological, ecological, geochronological, stable isotope, field, and satellite image data provide estimates of the delta's benthic productivity during the 1 k.y. directly preceding the artificial shutdown of the river. At least 2 × 1012 shells of bivalve mollusks make up the current beaches and islands of the delta. The 125 individual valves dated using 14C-calibrated amino acid racemization indicate that these shells range in age from A.D. 950 to 1950. Seasonal intrashell cycles in δ180 values indicate that average-sized bivalves lived at least 3 yr. The most conservative calculation based on these numbers indicates that during the time of natural river flow, an average standing population of ˜6 × 109 bivalve mollusks (population density ˜50/m2) thrived on the delta. In contrast, the present abundance of shelly benthic macroinvertebrates is ˜94% lower (3/m2 in 1999 2000). The dramatic decrease in abundance testifies to the severe loss of benthic productivity resulting from diversion of the river's flow and the inadequacy of its partial resumption (1981 to present). An integration of paleontological records with geomorphological, geochemical, and geochronological data can provide quantitative insights into human impact on coastal ecosystems.

  15. Morphodynamics of River Lowlands and Deltas: Combining Historical Maps with Satellite Data

    NASA Astrophysics Data System (ADS)

    Syvitski, J. P.; Hannon, M.; Kettner, A. J.; Jenkins, C. J.; Hutton, E. W.

    2007-12-01

    Cartographers have for centuries documented the courses of rivers and their delta's distributary channels. Yet these valuable historical maps have not often been placed into a Global Information System, and verified for their cartographic accuracy. We have obtained between 6 and 15 historical maps (17th - 20th century) for a set of global deltas (Indus, Ganges, Godavari, Krishna, Mahanadi, Brahmani, Yellow, Vistula Danube, Po, Rhone, Niger, Nile, Orinoco, Magdalena, Amazon, and Mississippi). The maps were examined for their registration accuracy, using the location of between 8 and 15 cities or towns. Those maps with RMS errors of less than 5 km had shape files established for the pathways of their rivers and distributary channels. Geolocated Space Shuttle Radar data were binned into 1 m topographic units (? 90 m horizontal footprint) for each river-delta system and used in combination with LANDSAT ETM+ (15-30 m horizontal footprint), as an underlay to each of the historical maps. The satellite data proved useful in verifying the historical courses of these channels, many of which are no longer active. Together the data provide valuable insight to the time dependent dynamics of distributary channel switching and migration, before the heavy anthropogenic footprint of the 20th century (river diversions through barrages, upstream damming of the sediment supply, mitigation of the seasonal flood wave, levee development and stabilization, human-affected delta subsidence, and agricultural infrastructure).

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

    NASA Astrophysics Data System (ADS)

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

    2015-12-01

    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.

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

    PubMed

    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.

  18. Private Challenges to Public Dominance: The Resurgence of Private Education in the Pearl River Delta.

    ERIC Educational Resources Information Center

    Mok, Ka-Ho

    1997-01-01

    Examines the policy context in which private education has emerged in post-Mao China. Uses three case studies of private schools/colleges to explore how intellectuals and educators in the Pearl River Delta (Guangdong province) have persevered to assert their academic independence, offer a new agenda for education, and redefine the private-public…

  19. Research Spotlight: What controls the shape of sediment channels in river deltas?

    NASA Astrophysics Data System (ADS)

    Tretkoff, Ernie

    2011-03-01

    When turbulent, sediment-filled rivers empty into oceans and lakes, the channels often divide repeatedly to form triangular deltas. Some channels, however, travel long distances before bifurcating, creating elongated channels. Understanding how these patterns arise could be useful for designing wetland restoration schemes on river deltas. Seeking to explain the conditions under which elongated channels form, Falcini and Jerolmack considered an analogy with cold filaments in ocean currents, in which high potential vorticity (a measure that combines the rotation of a flow with its thermal gradient) helps a filament hold a coherent structure over long distances. The researchers introduced a model that incorporates sediment concentration and fluid vorticity, to derive a new “potential vorticity” equation that describes sedimentation patterns at the river mouth. Their model shows that a high potential vorticity is needed for the creation of elongated channels, and their comparison to modeling, laboratory, and field studies confirms that potential vorticity is a primary control on channel morphology. The new model could help to understand the shape of the iconic Mississippi River delta and may aid in the design of proposed channel diversions there and in other deltas. (Journal of Geophysical Research-Earth Surface, doi:10.1029/2010JF001802, 2010)

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

    USGS Publications Warehouse

    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.

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

    PubMed

    Smith, James E; Bentley, Samuel J; Snedden, Gregg A; 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. PMID:26628104

  2. Sources of excess urban carbonaceous aerosol in the Pearl River delta region, China

    EPA Science Inventory

    Carbonaceous aerosol is one of the important constituents of fine particulate matter (PM2.5) in Southern China, including the Pearl River Delta (PRD) region and Hong Kong (HK). During the study period (October and December of 2002, and March and June of 2003), the monthly average...

  3. Sediment consolidation settlement of Chengbei Sea area in the northern Huanghe River subaqueous delta, China

    NASA Astrophysics Data System (ADS)

    Liu, Jie; Feng, Xiuli; Liu, Xiao

    2016-06-01

    One of the most important factors controlling the morphology of the modern Huanghe (Yellow) River delta is consolidation settlement, which is impacted by fast deposition, high water content, and low density of seafloor sediment. Consolidation settlement of the Huanghe River subaqueous delta was studied based on field data, laboratory experiments on 12 drill holes, and the one-dimensional consolidation theory. Results show that vertical sediment characteristics varied greatly in the rapidly forming sedimentary bodies of the modern Huanghe River subaqueous delta. Sediments in the upper parts of drill holes were coarser than those in the deeper parts, and other physical and mechanical properties changed accordingly. On the basis of the one-dimensional consolidation theory and drilling depth, the final consolidation settlement of drill holes was between 0.6 m and 2.8 m, and the mean settlement of unit depth was at 1.5-3.5 cm/m. It takes about 15-20 years for the consolidation degree to reach 90% and the average sedimentation rate within the overlying 50 m strata was at 5 cm/a to 12 cm/a. This study helps to forecast the final consolidation settlement and settlement rate of the modern Huanghe River subaqueous delta, which provides key geotechnical information for marine engineers.

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

    PubMed Central

    Smith, James E.; Bentley, Samuel J.; Snedden, Gregg A.; 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. PMID:26628104

  5. Biological assessment: water hyacinth control program for the Sacramento/ San Joaquin River Delta of California

    Technology Transfer Automated Retrieval System (TEKTRAN)

    A detailed Biological Assessment was developed for the proposed Areawide Water Hyacinth Control Program to outline the procedures that will be used to control this invasive aquatic plant in the Sacramento/ San Joaquin River Delta, and to help determine if this action is expected to threaten endanger...

  6. Recent morphological changes in the Mekong and Bassac river channels, Mekong delta: The marked impact of river-bed mining and implications for delta destabilisation

    NASA Astrophysics Data System (ADS)

    Brunier, Guillaume; Anthony, Edward J.; Goichot, Marc; Provansal, Mireille; Dussouillez, Philippe

    2014-11-01

    The Mekong delta, in Vietnam, is the world's third largest delta. Densely populated, the delta has been significantly armoured with engineering works and dykes to protect populations and infrastructure from storms, and shrimp farms from saltwater intrusion. Considerable development pressures in Vietnam and in the upstream countries have resulted in the construction of several dams in China and in important channel-bed aggregate extractions especially in Cambodia. The effects of these developments impact the delta dynamics in various ways. In this study, changes in the channel morphology of the Mekong proper and the Bassac, the two main distributaries in the 250 km-long deltaic reach from the Cambodian border to the coast, were analysed using channel depth data for 1998 and 2008. The channels display important and irregular bed changes over the 10-year comparison period, including significant incision and expansion and deepening of numerous pools. The mean depth of both channels increased by more than 1.3 m. Both channels also showed correlative significant bed material losses: respectively 90 million m3 in the Mekong and 110 million m3 in the Bassac over the 10-year period. These important losses over a relatively short period, and weak correlations between bed incision and hydraulic parameters suggest that the marked morphological changes are not in equilibrium with flow and sediment entrainment conditions, and are therefore not related to changes in river hydrology. We claim that aggregate extraction, currently practised on a very large scale in the Mekong delta channels and upstream of the delta, is the main cause of these recent morphological changes. These changes are deemed to contribute actively to rampant bank erosion in the delta as well as to erosion of the Mekong delta shoreline. Other contributory activities include the numerous dykes and embankments. The role of existing dams in bed losses remains unclear in the absence of reliable data on the Mekong

  7. Detection of Area Changes in River Mouthbars at the Mekong River Delta using ALOS/PALSAR data

    NASA Astrophysics Data System (ADS)

    Tanaka, A.; Uehara, K.; Tamura, T.; Saito, Y.

    2011-12-01

    Projected sea-level rise by the year 2100 would be ~1m recently and its negative impact on the coastal zone has been pointed out, particularly for mega-deltas in Asia by the Fourth Assessment Report of the Intergovernmental Panel on Climate Change (IPCC, 2007). The relative sea-level rise varies with specific conditions and processes over broad spatial and temporal scales. Therefore, long-term monitoring of geomorphological changes in coastal areas over wide areas is of highly interest and importance for coastal management. However, due to limited data availability and accessibility in developing countries, there is not enough systematic coastal monitoring. The Mekong River Delta is one of typical mega-deltas in Asia, which has a low-lying wide delta-plain located in Cambodia to South Vietnam. Sediment and water discharges of the Mekong River are controlled by the monsoon with high and low discharge in summer (wet season) and winter (dry season), respectively. Therefore, technologies such as SAR (Synthetic Aperture Radar) not affected by the cloud conditions offer potential for monitoring in the monsoon Asia region. In this study, ALOS (Advanced Land Observing Satellite) PALSAR (Phased Array type L-band SAR) data acquired over a period from December 2006 to January 2011 are analyzed to investigate the relation between the sea level and the shape of mouthbars in the Mekong River. Level-1.0 PALSAR data were processed, coregistered, and geocoded to make SAR backscatter intensity images. River mouthbars with strong backscatter, which is surrounded by the water with weak backscatter, are successfully extracted using a histogram thresholding algorithm. Estimated areas of river mouthbars, which are located at the central part of the delta and openly faced to the South China Sea, gradually increase on an annual time scale. These river mouthbars are growing to the seaward. Besides this overall increasing trend, seasonal variations of areas are observed; these correlate with

  8. Long-term NO2 monitoring by satellite in the Pearl River Delta

    NASA Astrophysics Data System (ADS)

    Li, Long; Shi, Runhe; Liu, Pudong; Zhang, Jie

    2013-09-01

    Recently, the air quality has been continuing to deteriorate and threaten public health in the Pearl River Delta. China, the host country for the 2010 Asian Games, faced the great challenge of air quality issues, particularly in the Pearl River Delta, where the Asian Games were held. The major aim of this study is to reveal the spatial and temporal characteristics of NO2 in the Pearl River Delta during October 2004 to December 2010. The long-term characteristics and variations of the NO2 column concentration before and during the 2010 Asian Games were analyzed by using the NO2 product OMNO2e from the Ozone Monitoring Instrument (OMI). Results show that the annual average of the NO2 column concentration has a significant downward trend from 2005 to 2010 in the Pearl River Delta: the total column concentration of NO2 (TotNO2) in the atmosphere decreased from 9.207×1015 molec/cm2 to 8.173×1015 molec/cm2, with an average annual rate of -2.247%; the tropospheric column concentration of NO2 (TropNO2)decreased from 6.685×1015 molec/cm2 to 5.646×1015 molec/cm2, with an average annual rate of -3.109%. The ratio TropNO2/TotNO2 indicating the amount of NO2 exhausted by human activities also decreased from 0.726 in 2005 to 0.691 in 2010. During the 2010 Asian Games, the weekly average of the TropNO2 in Pearl River Delta was maintained at a low level. The NO2 average distribution in the Pearl River Delta is characterized by the maximum in the geometric center, outwardly smaller, and the shrinking areas with high TropNO2 concentration from 2005 to 2010. Foshan, Jiangmen and Kwangchowan were severely polluted cities during the Games. However, the air quality of the Pearl River Delta was improved compared to its historical periods due to governmental preventive/control measures during the 2010 Asian Games.

  9. [Distribution and sources of polycyclic aromatic hydrocarbons in sediments from rivers of Pearl River Delta and its nearby South China Sea].

    PubMed

    Luo, Xiao-Jun; Chen, She-Jun; Mai, Bi-Xian; Zeng, Yong-Ping; Sheng, Guo-Ying; Fu, Jia-Mo

    2005-07-01

    Polycyclic aromatic hydrocarbons (PAHs) are measured in surface sediments from rivers and estuary of Pearl River Delta and its nearby South China Sea. Total PAH concentration varied from 255.9 - 16 670.3 ng/g and a moderate to low level compare to relevant areas worldwide. The order of PAHs concentration in sediments was: rivers of Pearl River Delta > estuary > South China Sea, and the most significant PAH contamination was at Guangzhou channel of Zhujiang river. A decrease trend for PAHs concentration with distance from estuary to open sea can be sees in South China Sea. Coal and biomass combustion is the major source of PAHs in nearshore of South China Sea, and petroleum combustion is the main source of pyrolytic PAHs in rivers and estuary of Pearl River Delta according to PAHs diagnostic ratios. Petroleum PAHs are revealed have a high contribution to PAHs in Xijiang River, estuary and some stations in Zhujiang River. A comparison of data from study in 1997 with data from present study indicates that there is no clear change in the PAH concentration over time but the source of PAHs in Pearl River Delta have been change from a main coal combustion to petroleum combustion and being reflect in the sediments in rivers and estuary of Pearl River Delta where there have high sedimentation rate.

  10. Geomorphic evolution of the Lilas River fan delta (Central Evia, Greece), during the Quaternary

    NASA Astrophysics Data System (ADS)

    Karymbalis, Efthimios; Valkanou, Kanella; Tsironis, Giorgos; Tsodoulos, Ioannis; Iliopoulos, George; Tsanakas, Konstantinos; Batzakis, Vasilis

    2015-04-01

    This study deals with the geomorphic evolution of the Lilas river fan delta, which is a late Holocene fan delta with an area of about 25 km2, extended mainly towards the south Evoikos Gulf and a secondary extension of approximately 5 km2 towards the north Evoikos Gulf (Central Evia Isl., Greece). This work has combined field geomorphological mapping with the study of the stratigraphy of late Pleistocene - Holocene deltaic sediments. A detailed geomorphic map at the scale of 1:5,000 has been prepared showing both the deltaic plain and the coastal zone features using GIS techniques. Comparative interpretation of aerial photographs taken in different dates and reliable maps of the last two centuries along with field observations depict recent changes of the delta morphology. Profiles of seven drill cores up to the depth of 70 m, provided by the municipality authorities, were considered in order to study the late Pleistocene - Holocene stratigraphy of the broader fan delta plain. Additionally, two boreholes reaching the depth of 4.75 m were drilled with a portable drilling set. The stratigraphy of the late Holocene sediments was studied in detail and 41 sediment samples, collected from selected sedimentary layers, were analyzed using micropaleontological and grain size analysis methods, while samples were dated using OSL. The study of the stratigraphy of the late Holocene deltaic sediments showed that during this period the sea invaded the area of the northwestern delta and created a shallow open marine environment which at times was disturbed by multiple quiet lagoonal phases of fine sediment deposition. Geomorphological mapping showed that among the most important factor for the recent development of the delta is fluvial sedimentation. The dominant landforms in the deltaic plain are the numerous abandoned palaeochannels. The main channel of the river changed its course several times leading to the building and subsequent abandonment of at least four fan delta lobes

  11. Sediment Bypassing of River Mouths: Mechanisms and Effects on Delta Evolution

    NASA Astrophysics Data System (ADS)

    Nienhuis, J.; Ashton, A. D.; Giosan, L.; Nardin, W.; Fagherazzi, S.

    2014-12-01

    Wave-influenced deltas are shaped by wave-driven transport of river-borne sediments. Near the river mouth, combined jet and wave dynamics, along with morphodynamic feedbacks, control the fraction of sediment transported alongshore by littoral currents that can bypass the river channel. Here we study how different bypassing rates influence large-scale delta evolution and examine the effect of waves and the river mouth jet on alongshore sediment bypassing. First, we use a modified version of the Coastline Evolution Model (CEM) to look at the effects of wave climate, fluvial sediment supply, and alongshore sediment bypassing rates on channel orientation. This modified version of CEM progrades the channel in a direction perpendicular to the local shoreline orientation at the river mouth, allowing feedbacks between alongshore sediment transport and fluvial sediment delivery to steer the river channel. Additionally, we allow a prescribed fraction of littoral sediment to bypass the river mouth. We find that deltas that have a large fluvial sediment flux can orient themselves into the direction of dominant wave approach. Lower fluvial inputs result in channels that are deflected downdrift, with increasing deflection as bypassing is reduced. In contrast, channels do not deflect downdrift (but can reorient themselves updrift for large fluvial fluxes) when full bypassing is allowed. These results demonstrate the importance of river mouth sediment bypassing on delta growth patterns, but, as we explore arbitrary bypassing laws, the simulations cannot help us constrain natural bypassing fluxes. To further investigate the natural extent and mechanisms of bypassing, we use the coupled hydrodynamic and morphodynamic model Delft3D-SWAN. With a simplified shoreface and river channel, the model is able to construct river mouth morphology from the combined action of alongshore transport and a river mouth jet. Exploring river mouth morphology and sediment bypassing under various wave

  12. Dispersal of larval suckers at the Williamson River Delta, Upper Klamath Lake, Oregon, 2006-09

    USGS Publications Warehouse

    Wood, Tamara M.; Hendrixson, Heather A.; Markle, Douglas F.; Erdman, Charles S.; Burdick, Summer M.; Ellsworth, Craig M.; Buccola, Norman L.

    2012-01-01

    An advection/diffusion modeling approach was used to simulate the transport of larval suckers from spawning areas in the Williamson River, through the newly restored Williamson River Delta, to Upper Klamath Lake. The density simulations spanned the years of phased restoration, from 2006/2007 prior to any levee breaching, to 2008 when the northern part of the delta was reconnected to the lake, and 2009 when levees on both sides of the delta had been breached. Model simulation results from all four years were compared to field data using rank correlation. Spearman ρ correlation coefficients were usually significant and in the range 0.30 to 0.60, providing moderately strong validation of the model. The correlation coefficients varied with fish size class in a way that suggested that the model best described the distribution of smaller fish near the Williamson River channel, and larger fish away from the channel. When Lost River and shortnose/Klamath largescale suckers were simulated independently, the correlation results suggested that the model better described the transport and dispersal of the latter species. The incorporation of night-time-only drift behavior in the Williamson River channel neither improved nor degraded correlations with field data. The model showed that advection by currents is an important factor in larval dispersal.

  13. Chlorinated and polycyclic aromatic hydrocarbons in riverine and estuarine sediments from Pearl River Delta, China.

    PubMed

    Mai, Bi-Xian; Fu, Jia-Mo; Sheng, Guo-Ying; Kang, Yue-Hui; Lin, Zheng; Zhang, Gan; Min, Yu-Shuan; Zeng, Eddy Y

    2002-01-01

    Spatial distribution of chlorinated hydrocarbons [chlorinated pesticides (CPs) and polychlorinated biphenyls (PCBs)] and polycyclic aromatic hydrocarbons (PAHs) was measured in riverine and estuarine sediment samples from Pearl River Delta, China, collected in 1997. Concentrations of CPs of the riverine sediment samples range from 12 to 158 ng/g, dry weight, while those of PCBs range from 11 to 486 ng/g. The CPs concentrations of the estuarine sediment samples are in the range 6-1658 ng/g, while concentrations of PCBs are in the range 10-339 ng/g. Total PAH concentration ranges from 1168 to 21,329 ng/g in the riverine sediment samples, whereas the PAH concentration ranges from 323 to 14,812 ng/g in the sediment samples of the Estuary. Sediment samples of the Zhujiang River and Macao harbor around the Estuary show the highest concentrations of CPs, PCBs, and PAHs. Possible factors affecting the distribution patterns are also discussed based on the usage history of the chemicals, hydrologic condition, and land erosion due to urbanization processes. The composition of PAHs is investigated and used to assess petrogenic, combustion and naturally derived PAHs of the sediment samples of the Pearl River Delta. In addition, the concentrations of a number of organic compounds of the Pearl River Delta samples indicate that sediments of the Zhujiang river and Macao harbor are most likely to pose biological impairment.

  14. Changing river courses in the western part of the Ganga-Brahmaputra delta

    NASA Astrophysics Data System (ADS)

    Rudra, Kalyan

    2014-12-01

    The Ganga-Brahmaputra delta is the largest on Earth, the product of two of the world's largest and siltiest rivers. It is formed in a basin located over the zone where the Indian plate subducts beneath the Himalaya to the north and the Indo-Burman ranges to the east. The distributaries in the south-western part of the delta remain disconnected from the Ganga-Padma during the lean season, although they are still active in bank erosion and sediment transport during the monsoon. Four distributaries of the Bhagirathi-Hugli (the westernmost branch of the Ganga) have gone dry during known historical period. In many cases, the natural decay of rivers has been exacerbated by the human intervention, especially where rivers are embanked and no allowance made for their migration through meandering and avulsion. In the coastal zone where mangroves were cleared and creeks were embanked since the late 18th century, decay of channels, and advancement of the sea towards inland have been aggravated. The subsequent attempt of flushing the sediment load to the sea from the estuary to improve the status of navigation in the Bhagirathi-Hugli River was not successful to the level of expectation. This paper deals with the decay and changing courses of rivers in the western part of the Ganga-Brahmaputra delta.

  15. Land use/land cover change in Yellow River Delta, China during fast development period

    NASA Astrophysics Data System (ADS)

    Zhou, Wenzuo; Tian, Yongzhong; Zhu, Lifen

    2007-09-01

    Terrestrial eco-system in coastal zones is unstable and land-use and Land-cover of its land resource are crucial for its sustainability. Therefore it is necessary to understand distribution of land use/cover changes in those tender areas. This paper was to analyze changes of land use/cover in Yellow River Delta in China during recent ten years, which was its fast development period, by remote sensing monitoring. Two Landsat TM images in October of 1995 and 2004 were processed using ERDAS software and supervised classification method in study for the land use and land cover of those two years. The two land use/cover maps were overlaid to discover the changes. It was showed that lots of land use/cover changes in the Yellow River Delta had taken place in past ten years. Because abundant sand that carried by river water filled up at estuary of the Yellow River, new land increased fleetly. The rates that foreshore were turned into fishery land was high for aquaculture with salt water had been developed quickly. Another important effect of human activity was that part of waste land and grassland had been cultivated for crops. With industry and economy development, land for urbanization had been outspreaded. Although fast exploitation had been carried out in Yellow River Delta going though those years, some human activities on land use were inharmonious for sustainable development of land resource in this area. This must be pay attention to by local government and people.

  16. Delta distributary dynamics in the Skagit River Delta (Washington, USA): Extending, testing, and applying avulsion theory in a tidal system

    NASA Astrophysics Data System (ADS)

    Hood, W. Gregory

    2010-11-01

    Analysis of historical aerial photos shows that Skagit Delta (Washington, USA) distributary dynamics are consistent with the Slingerland and Smith model of avulsion dynamics where the ratio of the water surface slopes of the two branches of a bifurcation predicts avulsion stability. This model was extended to predict distributary inlet (upstream) width and bankfull cross-sectional area. The water surface gradient ratio for a bifurcation pair predicted distributary width well; the lowest R2 was 0.61 for the 1937 data points, but R2 ranged from 0.83 to 0.90 for other year-specific regression lines. Gradient ratios were not constant over the historical record; from 1937 to 1972 the mainstem river channel lengthened by 1250 m in the course of marsh progradation, while distributary lengthening was comparatively negligible. Consequently, the gradient advantage of the distributaries increased and their channels widened. After the mainstem river terminus stabilized from 1972 to the present, the distributaries continued to lengthen with marsh progradation, so that distributary gradient advantage steadily declined and the distributaries narrowed. While distributary cross sections were not available for the historical period, they were surveyed in 2007 near the distributary inlets. Gradient ratio was more closely related to distributary inlet bankfull cross-sectional area ( R2 = 0.95) than to minimum distributary width for any photo year examined. Applying this form of analysis to Skagit Delta distributaries that have been dammed in the course of agricultural development suggests that their restoration to stabilize eroding marshes at their outlets and recover salmon migration pathways would be feasible without significant risk of full river avulsion.

  17. Sources, bioavailability, and photoreactivity of dissolved organic carbon in the Sacramento-San Joaquin River Delta

    USGS Publications Warehouse

    Stepanauskas, R.; Moran, M.A.; Bergamaschi, B.A.; Hollibaugh, J.T.

    2005-01-01

    We analyzed bioavailability, photoreactivity, fluorescence, and isotopic composition of dissolved organic carbon (DOC) collected at 13 stations in the Sacramento-San Joaquin River Delta during various seasons to estimate the persistence of DOC from diverse shallow water habitat sources. Prospective large-scale wetland restorations in the Delta may change the amount of DOC available to the food web as well as change the quality of Delta water exported for municipal use. Our study indicates that DOC contributed by Delta sources is relatively refractory and likely mostly the dissolved remnants of vascular plant material from degrading soils and tidal marshes rather than phytoplankton production. Therefore, the prospective conversion of agricultural land into submerged, phytoplankton-dominated habitats may reduce the undesired export of DOC from the Delta to municipal users. A median of 10% of Delta DOC was rapidly utilizable by bacterioplankton. A moderate dose of simulated solar radiation (286 W m-2 for 4 h) decreased the DOC bioavailability by an average of 40%, with a larger relative decrease in samples with higher initial DOC bioavailability. Potentially, a DOC-based microbial food web could support ???0.6 ?? 109 g C of protist production in the Delta annually, compared to ???17 ?? 109 g C phytoplankton primary production. Thus, DOC utilization via the microbial food web is unlikely to play an important role in the nutrition of Delta zooplankton and fish, and the possible decrease in DOC concentration due to wetland restoration is unlikely to have a direct effect on Delta fish productivity. ?? Springer 2005.

  18. Heavy Metals and Biogenic Elements in Aquatic Systems of the Don River Delta

    NASA Astrophysics Data System (ADS)

    Tkachenko, Anna; Tkachenko, Oleg

    2014-05-01

    River deltas are located in the lower parts of the cascade landscape-geochemical systems of the river basins, so their geochemical conditions often characterize the anthropogenic impact on whole river system. The Don River runs through the one of the most agriculturally developed and densely populated area of Russia, and flows into the Azov Sea - the smallest and shallowest sea in the world. These factors determine the geochemical features of aquatic systems of the Don River mouth area and the specificity of the "river-sea" geochemical barrier zone. The paper presents results of the field studies of the geochemical structure of the Don River mouth area, which were conducted in frames of the RFBR project in 2012-2013. Major types of the deltaic water streams and bodies were studied in different hydrological seasons: spring floods, summer, autumn and winter low water periods. About 50 samples of water, suspended matter and 60 samples of bottom sediments have been collected and analyzed for heavy metals (Fe, Mn, Zn, Cu, Ni, Co, Pb, Cr, Cd etc.) and biogenic elements (nitrate, nitrite, ammonium, phosphates, silica, total nitrogen and phosphorus, dissolved oxygen and chlorophyll) content. To assess the toxicity degree and nutrient potential of water, bioassay test conducted by growing daphnia in water samples were held. The study shows that the Don River delta water is characterized by the relatively low values of dissolved heavy metal content. Significantly higher values of heavy metals were determined in the vicinity of settlements only. Metal accumulation in bottom sediments can be associated mainly with the rate of water flow. Higher values were found in sediments of small channels with weak flow velocity and prevailing processes of the suspended matter deposition. The data on the seasonal dynamics of nutrients and spatial variability of their forms have been obtained. The maximum concentration of nitrogen, phosphorus, silicon, and other biogenic elements are

  19. SAR Interferometry as a Tool for Monitoring Coastal Changes in the Nile River Delta of Egypt

    NASA Technical Reports Server (NTRS)

    Aly, Mohamed H.; Klein, Andrew G.; Giardino, John R.

    2005-01-01

    The Nile River Delta is experiencing rapid rates of coastal change. The rate of both coastal retreat and accretion in the Eastern Nile Delta requires regular, accurate detection and measurement. Current techniques used to monitor coastal changes in the delta are point measurements and, thus, they provide a spatially limited view of the ongoing coastal changes. SAR interferometry can provide measurements of subtle coastal change at a significantly improved spatial resolution and over large areas (100 sq km). Using data provided by the ERS-1&2 satellites, monitoring can be accomplished as frequently as every 35 days when needed. Radar interferometry is employed in this study to detect segments of erosion and accretion during the 1993-2000 period. The average rates of erosion and accretion in the Eastern Nile Delta are measured to be -11.64 m/yr and +5.12 m/yr, respectively. The results of this interferometric study can be used effectively for coastal zone management and integrated sustainable development for the Nile River Delta.

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

    USGS Publications Warehouse

    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.

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

    USGS Publications Warehouse

    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

  2. Flooding the Colorado River Delta: A Landscape-Scale Experiment

    NASA Astrophysics Data System (ADS)

    Flessa, Karl W.; Glenn, Edward P.; Hinojosa-Huerta, Osvel; Parra-Rentería, Carlos A.; Ramírez-Hernández, Jorge; Schmidt, John C.; Zamora-Arroyo, Francisco A.

    2013-12-01

    A large pulse of water is planned to be released into the dry Colorado River channel in Mexico. This engineered experimental spring flood, which will flow from Lake Mead and pass through downstream reservoirs, is the culmination of decades of applied research. The pulse flow is a rare opportunity for research at the landscape scale [Glenn et al., 2013].

  3. Land subsidence at aquaculture facilities in the Yellow River delta, China

    NASA Astrophysics Data System (ADS)

    Higgins, Stephanie; Overeem, Irina; Tanaka, Akiko; Syvitski, James P. M.

    2013-08-01

    Differential Interferometric Synthetic Aperture Radar is applied to the coast of the Yellow River delta (YRD) in China. Like many deltas, the coastline of the YRD is dominated by aquaculture. Advanced Land Observation Satellite Phased Array L-Band Synthetic Aperture Radar (SAR) and Envisat Advanced SAR data acquired between 2007 and 2011 show that subsidence rates are as high as 250 mm/y at aquaculture facilities, likely due to groundwater pumping. These rates exceed local and global average sea level rise by nearly 2 orders of magnitude and suggest that subsidence and associated relative sea level rise may present a significant hazard for Asian megadeltas.

  4. 2500 years of changing shoreline accretion rates at the mouths of the Mekong River delta

    NASA Astrophysics Data System (ADS)

    Besset, Manon; Tamura, Toru; Anthony, Edward; Brunier, Guillaume; Saito, Yoshiki; Dussouillez, Philippe; Lap Nguyen, Van; Ta, Oahn

    2016-04-01

    The Mekong River delta prograded rapidly in a relatively sheltered bight in the South China Sea under the influence of high fluvial sediment supply 5300 to 3500 years ago, developing from an estuary into a delta. This >200 km seaward growth resulted in increasing exposure of the delta to ocean waves that led to a more wave-influenced mode of progradation characterized by the construction of numerous sets of beach ridges in the eastern sector of the delta, which shows a system of multiple distributary mouths. The growth pattern of this river-mouth sector over the last 2500 years has been determined from OSL dating of these beach-ridge deposits, while the most up-to-date trends (1950-2014) have been highlighted from the analysis of maps and satellite images. The OSL ages show that the area of the delta in the mouths sector remained nearly constant till about 500 yr BP, following which significant accretion occurred, possibly in response to changes in catchment land-use and monsoon rainfall and attendant river water and sediment discharge. A fine-tuned analysis of changes since 1950 shows dominant but fluctuating accretion, with two periods of erosion. The first (1965-1973) occurred in the course of the second Indochina war, and the second more recently from 2003 to 2011, followed by mild recovery between 2011 and 2014. These fluctuations most likely reflect changes in sediment supply caused by the vicissitudes of war and its effect on vegetation cover, as well as variations in monsoon rainfall and discharge, and, for the most recent period, massive sand mining in the river and deltaic channels. Accretion of the mouths sector has gone apace, over the same recent multi-decadal period, with large-scale erosion of the muddy shores of the delta in the western South China Sea and the Gulf of Thailand, thus suggesting that the mouths sector may be increasingly sequestering sediment to the detriment of the rest of the delta shoreline. The accretion in the mouths sector is

  5. Quantifying the transition from fluvial- to wave-dominance for river deltas with multiple active channels

    NASA Astrophysics Data System (ADS)

    Nienhuis, J.; Ashton, A. D.; Giosan, L.

    2012-12-01

    The plan-view morphologies of fluvial- and wave-dominated deltas are clearly distinctive, but transitional forms are numerous. A quantitative, process-based description of this transition remains unexplored, particularly for river deltas with multiple active channels. Previous studies focused on general attributes of the fluvial and marine environment, such as the balance between wave energy and river discharge. Here, we propose that the transition between fluvial and wave dominance is directly related to the magnitude of the fluvial bedload flux to the nearshore region versus the alongshore sediment transport capacity of waves removing sediment away from the mouth. In the case of a single-channel delta, this balance can be computed for a given distribution of waves approaching shore. Fluvial dominance occurs when fluvial sediment input exceeds the wave-sustained maximum alongshore sediment transport for all potential shoreline orientations both up- and downdrift of the river mouth. However, deltaic channels have the tendency to bifurcate with increasing fluvial strength. Initial bifurcation splits the fluvial sediment flux among individual channels, while the potential sediment transport by waves remains constant for both river mouths. At higher bifurcation orders, multiple channels interact with each other alongshore, a situation more complicated than the single channel case and one that cannot be simple addressed analytically. We apply a model of plan-view shoreline evolution to simulate the evolution of a deltaic environment with multiple active channels. A highly simplified fluvial domain is represented by deposition of sediment where channels meet the coast. We investigate two scenarios of fluvial delivery. The first scenario deposits fluvial sediment alongshore on a self-similar predefined network of channels. We analyze the effects of different network geometrical parameters, such as bifurcation length, bifurcation angle, and sediment partitioning. In the

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

    USGS Publications Warehouse

    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

  7. Dam Removal as Nearshore Restoration - Patterns and Processes of the Elwha River Delta

    NASA Astrophysics Data System (ADS)

    Warrick, J. A.; Gelfenbaum, G.; Johannessen, J.; Beirne, M.; Winter, B.

    2005-12-01

    Dams on the Elwha River of the Olympic Peninsula have reduced sediment transport in the river for almost a century. Following dam removal, which is slated to begin in 2008, over 14 million cubic meters of mixed grain-size sediments will be exposed in the former reservoirs, much of which will erode and transport to the Strait of Juan de Fuca. Increased supply of sediment to the strait, may end, or perhaps reverse, the current trend of erosion along the river delta and adjacent shoreline. Here we describe the history of shoreline evolution along the Elwha River delta and detail monitoring plans to track nearshore changes following dam removal. Historic data document a general trend of erosion along the delta resulting in a net loss of approx. 65,000 sq. meters of land between 1926 and 1995, although variability in erosion rates is observed over both space and time. Continued monitoring of the shoreface is planned by both U.S. Geological Survey (USGS) and Lower Elwha Klallam Tribe (LEKT) scientists. USGS scientists have also implemented a research program that includes beach and nearshore mapping, process (wave and current) monitoring, and numerical modeling of sediment dispersal. Here we will present preliminary results of this work including high-resolution seabed maps of bathymetry and sediment type and changes in the nearshore bathymetry and beach topography from semi-annual mapping using RTK GPS technologies.

  8. Impacts of urbanization on hydrology in the Yangtze River Delta, China.

    PubMed

    Youpeng, Xu; Jintao, Xu; Jinjia, Ding; Ying, Chen; Yixing, Yin; Xingqi, Zhang

    2010-01-01

    The Yangtze River Delta is one of the most developed regions in China and the rapid development of urbanization have greatly influenced regional hydrology and water resources. Taking several typical urbanizing areas in the Yangtze River Delta as examples, this paper probes into the impacts of urbanization on hydrologic cycle and hydrological process with the support of RS, GIS and hydrological model. The research centers on the impacts of urbanization on precipitation, hydrological process, river networks, and water environment in some typical cities. The results show that: (1) Urban rain island effect is not evident when the process of urbanization is slow, while the differences of annual precipitation and flood season precipitation between urban and suburban areas increased to a certain extent in the booming stage of urbanization. (2) The annual runoff depth and the runoff coefficient increased with the development of urbanization, and the effect will be more notable when the urban areas expand to a certain size; (3) River network systems, especially low-grade rivers have been greatly destroyed in the process of urbanization, which increases the risk of flood and water degradation, so it is very important to protect natural river systems. Based on the results, some proposals of sustainable utilization and protection of water resources is also addressed.

  9. How Does the Morphology of Shelf-Margin Deltas Relate to Sea-Level Elevation? Clues From the Modern Mississippi River Delta

    NASA Astrophysics Data System (ADS)

    Ghoshal, S.; Bart, P. J.

    2005-12-01

    Scientists have attempted to precisely determine eustatic changes using various techniques. One of these is the sequence stratigraphic technique which relies on vertical changes in the position of coastal onlap (Vail et al, 1977). In subsequent years, several authors have recognized many limitations in this approach (Christie-Blick et al., 1990). Our ongoing study focuses on the possibility of using the morphology of modern and ancient shelf-margin deltas as sea-level indicators to determine past sea-level elevations. The Mississippi River Delta provides an excellent opportunity to study the precise relationship between shelf-edge delta morphology and sea-level elevation. A morphological analysis of the modern Mississippi River Delta suggests that there may be a direct relationship between the sea-level and the offlap break features of the delta. The offlap break is defined at the intersection of topset and foreset at the location of a marked increase in slope. At this point, the bathymetric curvature (i.e. second derivative of sea-floor) is highest. This is analogous to O'Grady and Syvitski (2002) definition of shelf break offshore Greenland. More than a hundred bathymetric cross sections were made across the modern Balize lobe of the Mississippi River Delta using Rivertools software. The geomorphic analysis showed that there were two distinct morphologic types of the delta. In one type, there is a sharp transition from the topset to the foreset, whereas in a second type, the topset-foreset transition is gradual. It was observed that sharp offlap breaks characterize the eastern part of the delta at water depths of 1 ± 0.3 m. The southern and southwestern parts of the delta are characterized by gradual offlap breaks at water depths of 4 ± 2 m.

  10. Basin-Scale Exports vs. Coastal Delivery of Carbon, Nutrients and Particulates Above and Below Arctic River Deltas

    NASA Astrophysics Data System (ADS)

    Striegl, R. G.; Tank, S. E.; Weeks, G.; Holmes, R. M.; McClelland, J. W.

    2014-12-01

    Recent studies have substantially improved our understanding of water, sediment and materials exports by arctic rivers. Seasonality of exports, particularly during the spring freshet, is better quantified, as are the inland sources of water and sediment discharge and the source and chemical character of other material exports, including carbon and nutrients. Measurements on small rivers discharging directly to the Arctic Ocean and lacking complex deltas can accurately quantify local inputs to coastal regions. However, the majority of hydrologic inputs to the Arctic Ocean derive from 6 major Eurasian and North American rivers. Water, sediment, and chemical exports from these rivers are typically measured above head of tide, far inland, and commonly above large river deltas. These deltas settle particles and provide favorable environments for deposition, storage, and biogeochemical consumption, production, and transformation of aquatic carbon and nutrients. Consequently, basin exports measured above river deltas likely misrepresent actual delivery to coastal regions. In addition to accumulating sediment, observed and modeled arctic delta effects include enrichment of the organic content of suspended solids, increased dissolved organic carbon and nitrogen (DOC; DON) concentration, decreased inorganic nutrient concentration, and settling and likely increased bioavailability of particle associated contaminants, such as mercury. Increased DOC concentration in the Mackenzie River delta has also been associated with a change in DOC quality, with increased potential for biodegradation of DOC and decreased potential for photodegradation of DOC from head of tide to within the delta. For the most part, assessments of differences between head of tide basin exports and coastal delivery tend to be qualitative rather than quantitative, largely because of difficulties quantifying tidally affected flow. This points to the need to resolve data gaps, improve quantitative assessments

  11. The combined impact on the flooding in Vietnam's Mekong River delta of local man-made structures, sea level rise, and dams upstream in the river catchment

    NASA Astrophysics Data System (ADS)

    Le, Thi Viet Hoa; Nguyen, Huu Nhan; Wolanski, Eric; Tran, Thanh Cong; Haruyama, Shigeko

    2007-01-01

    The Mekong River delta plays an important role in the Vietnamese economy and it has been severely impacted during this century by a series of unusually large floods. In the dry season the delta is also impacted by salinity intrusion and tides. These effects have caused severe human hardship. To mitigate these impacts, a large number of engineering structures, primarily dykes and weirs, have been built in the delta in recent years and are still being built, mainly to control floods and saltwater intrusion. These control measures are still being upgraded. A GIS-linked numerical model shows that the flood levels in the delta depend on the combined impacts of high river flows in the Mekong River, storm surges, sea level rise, and the likely, future siltation of the Mekong Estuary resulting from the construction of dams in China as well as many other dams proposed throughout the remaining river catchment. The model suggests that the engineering structures in the delta increase the flow velocities in the rivers and canals, increasing bank erosion, and cause the water to be deeper in the rivers and canals. This increases flooding in the non-protected areas of the delta and increases the risk of catastrophic failure of the dykes in the protected areas. The model also predicts that a sea level rise induced by global warming will enhance flooding in the Mekong River delta in Vietnam, and that flooding may worsen in the long term as a result of estuarine siltation resulting from the construction of dams. At the scale of the Mekong River basin, a multinational water resources management plan is needed that includes the hydrological needs of the delta. At the scale of the delta, a compromise is needed between allowing some flooding necessary for agriculture and preventing catastrophic flooding to alleviate human suffering.

  12. DELTAE

    SciTech Connect

    Ward, W.C. )

    1993-11-01

    In thermoacoustic engines and refrigerators, and in many simple acoustic systems, a one dimensional wave equation determines the spatial dependence of the acoustic pressure and velocity. DELTAE numerically integrates such wave equations in the acoustic approximation, in gases or liquids, in user-defined geometries. Boundary conditions can include conventional acoustic boundary conditions of geometry and impedance, as well as temperature and thermal power in thermoacoustic systems. DELTAE can be used easily for apparatus ranging from simple duct networks and resonators to thermoacoustic engines refrigerators and combinations thereof. It can predict how a given apparatus will perform, or can allow the user to design an apparatus to achieve desired performance. DELTAE views systems as a series of segments; twenty segment types are supported. The purely acoustic segments include ducts and cones, and lumped impedances including compliances, series impedances, and endcaps. Electroacoustics tranducer segments can be defined using either frequency-independent coefficients or the conventional parameters of loudspeaker-style drivers: mass, spring constant, magnetic field strength, etc. Tranducers can be current driven, voltage driven, or connected to an electrical load impedance. Thermoacoustic segment geometries include parallel plates, circular and rectangular pores, and pin arrays. Side branches can be defined with fixed impedances, frequency-dependent radiation impedances, or as an auxiliary series of segments of any types. The user can select working fluids from among air, helium, neon, argon, hydrogen, deuterium, carbon dioxide, nitrogen, helium-argon mixtures, helium-xenon mixtures, liquid sodium, and eutectic sodium-potassium. Additional fluids and solids can be defined by the user.

  13. Decades of Change on the Ganges-Brahmaputra Delta; Rivers, Coastlines, Agriculture and Development

    NASA Astrophysics Data System (ADS)

    Small, C.; Sousa, D.; Chiu, S.; Mondal, D. R.; Steckler, M. S.; Akhter, S. H.; Mia, B.; Goodbred, S. L., Jr.; Wilson, C.; Seeber, L.

    2014-12-01

    The Ganges-Brahmaputra delta (GBD) is formed by the convergence of two great rivers, superlative in both size and geologic activity. The GBD is home to > 150 million people with a mean population density of more than 1000 people/km2. The fertile soils, abundant water and favorable climate also make the delta one of the most agriculturally diverse and productive areas on Earth. We seek to better understand the coupled natural and anthropogenic dynamics of the delta through a number of cross-disciplinary field studies of the contributing geophysical, biophysical and anthropogenic processes. To provide a synoptic multitemporal perspective for these studies, we use a variety of remotely sensed observations collected over the delta since 1988. In this overview we provide a synthesis of recent results from studies of 4 interrelated processes; river channel migration, coastal erosion and deposition, co-evolution of agriculture and aquaculture, and economic development. In each study we use multi-sensor spatiotemporal analysis of remotely sensed imagery spanning more than 2 decades to observe and quantify a variety of processes at multiple spatial and temporal scales. MODIS Enhanced Vegetation Index (EVI) composites provide 16 day temporal and 250m spatial resolution of the entire delta from 2000 to present. This image time series captures not only agricultural phenology over the entire delta but also the development of aquaculture on the lower delta and interannual fluvial dynamics on both the Ganges and Brahmaputra rivers. Landsat TM, ETM+ and OLI allow us to represent land cover as continuous fields of soil and sediment substrate, vegetation and dark surfaces (water and shadow) throughout the delta since 1988. Despite its irregular temporal sampling, Landsat's 30 m pixels better resolve both natural and anthropogenic land cover units and its longer time series extends retrospective analyses back to 1988. More recent sensors like Ikonos, Quickbird, GeoEye and World

  14. Assessing Subaqueous Mudflow Hazard on the Mississippi River Delta Front, Part 1: A Historical Perspective on Mississippi River Delta Front Sedimentation

    NASA Astrophysics Data System (ADS)

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

    2014-12-01

    Subaqueous mudflows are known to be ubiquitous across the Mississippi River delta front (MRDF) and have been identified as a hazard to offshore infrastructure. Among other factors, sediment accumulation rates and patterns play an important role in governing the stability of delta front sediment. High sedimentation rates result in underconsolidation, slope steepening, and increased biogenic gas production, which are all known to decrease stability. Sedimentation rates are highly variable across the MRDF, but are highest near the mouth of Southwest Pass, which carries the largest percentage of Mississippi River sediment into the Gulf of Mexico. Since the 1950s, the sediment load of the Mississippi River has decreased by ~50% due to dam construction upstream. The impact of this decreased sediment load on MRDF mudflow dynamics has yet to be examined. We compiled MRDF bathymetric datasets, including historical charts, industry and academic surveys, and NOAA data, collected between 1764 and 2009, in order to identify historic trends in sedimentation patterns. The progradation of Southwest Pass (measured at 10 m depth contour) has slowed from ~66 m/yr between 1764 and 1940 to ~25 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. Advancement of the delta also decelerated in deeper water (15-90 m) offshore from Southwest Pass. In this area, from 1940-1979, depth contours advanced seaward ~25 m/yr, but did not advance from 1979-2005. Furthermore, over the same area and time ranges, the sediment accumulation rate decreased by ~82%. We expect these sedimentation trends are occurring across the delta front, with potential impacts on spatial and temporal patterns of subaqueous mudflows. The MRDF appears to be entering a phase of decline, which will likely be accelerated by future upstream sediment diversion projects. New geophysical data will be required to assess

  15. Environmental and eelgrass response to dike removal: Nisqually River Delta (2010–14)

    USGS Publications Warehouse

    Takesue, Renee K.

    2016-10-03

    Restoration of tidal flows to formerly diked marshland can alter land-to-sea fluxes and patterns of accumulation of terrestrial sediment and organic matter, and these tidal flows can also affect existing nearshore habitats. Dikes were removed from 308 hectares (ha) of the Nisqually National Wildlife Refuge on the Nisqually River Delta in south Puget Sound, Washington, in fall 2009 to improve habitat for wildlife, such as juvenile salmon. Ecologically important intertidal and subtidal eelgrass (Zostera marina) beds grow on the north and west margins of the delta. The goal of this study was to understand long-term changes in eelgrass habitat and their relation to dike removal. Sediment and eelgrass properties were monitored annually in May from 2010 to 2014 at two sites on the west side of the Nisqually River Delta along McAllister Creek, a spring-fed creek near two restored tidal channels. In May 2014, the mean canopy height of eelgrass was the same as in previous years in an 8-ha bed extending to the Nisqually River Delta front, but mean canopy height was 20 percent lower in a 0.3-ha eelgrass bed closer to the restored marsh when compared to mean canopy height of eelgrass in May 2010, 6 months after dike removal was completed. Over 5 years, the amount of eelgrass leaf area per square meter (m2) in the 8-ha bed increased slightly, and surface-sediment grain size became finer. In contrast, in the 0.3-ha bed, eelgrass leaf area per m2 decreased by 45 percent, and surface sediment coarsened. Other potential stressors, including sediment pore water reduction-oxidation potential (redox) and hydrogen sulfide (H2S) concentration in the eelgrass rhizosphere, or root zone, were below levels that negatively affect eelgrass growth and therefore did not appear to be environmental stressors on plants. Eelgrass biomass partitioning, though less favorable in the 8-ha eelgrass bed compared to the 0.3-ha one, was well above the critical above-ground to below-ground biomass ratio of

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

    PubMed

    Berg, Michael; Stengel, Caroline; Pham, Thi Kim Trang; Pham, Hung Viet; 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 microg/L in Cambodia (average 217 microg/L) and 1-845 microg/L in southern Vietnam (average 39 microg/L), respectively. It also evaluates the situation in Red River delta where groundwater arsenic concentrations vary from 1-3050 microg/L (average 159 microg/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 microg/g (average 7 microg/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 microg/L have a significantly higher arsenic content than control groups (<50 microg/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.

  17. Environmental and Eelgrass Response to Dike Removal: Nisqually River Delta (2010–14)

    USGS Publications Warehouse

    Takesue, Renee K.

    2016-10-03

    Restoration of tidal flows to formerly diked marshland can alter land-to-sea fluxes and patterns of accumulation of terrestrial sediment and organic matter, and these tidal flows can also affect existing nearshore habitats. Dikes were removed from 308 hectares (ha) of the Nisqually National Wildlife Refuge on the Nisqually River Delta in south Puget Sound, Washington, in fall 2009 to improve habitat for wildlife, such as juvenile salmon. Ecologically important intertidal and subtidal eelgrass (Zostera marina) beds grow on the north and west margins of the delta. The goal of this study was to understand long-term changes in eelgrass habitat and their relation to dike removal. Sediment and eelgrass properties were monitored annually in May from 2010 to 2014 at two sites on the west side of the Nisqually River Delta along McAllister Creek, a spring-fed creek near two restored tidal channels. In May 2014, the mean canopy height of eelgrass was the same as in previous years in an 8-ha bed extending to the Nisqually River Delta front, but mean canopy height was 20 percent lower in a 0.3-ha eelgrass bed closer to the restored marsh when compared to mean canopy height of eelgrass in May 2010, 6 months after dike removal was completed. Over 5 years, the amount of eelgrass leaf area per square meter (m2) in the 8-ha bed increased slightly, and surface-sediment grain size became finer. In contrast, in the 0.3-ha bed, eelgrass leaf area per m2 decreased by 45 percent, and surface sediment coarsened. Other potential stressors, including sediment pore water reduction-oxidation potential (redox) and hydrogen sulfide (H2S) concentration in the eelgrass rhizosphere, or root zone, were below levels that negatively affect eelgrass growth and therefore did not appear to be environmental stressors on plants. Eelgrass biomass partitioning, though less favorable in the 8-ha eelgrass bed compared to the 0.3-ha one, was well above the critical above-ground to below-ground biomass ratio of

  18. Is It Feasible to Build New Land in the Mississippi River Delta?

    NASA Astrophysics Data System (ADS)

    Kim, Wonsuck; Mohrig, David; Twilley, Robert; Paola, Chris; Parker, Gary

    2009-10-01

    What if the Mississippi River levees were cut below New Orleans? What if much of the water and sediment were allowed to flow out and build new deltas? Could deltaic land loss be reversed, and indeed restored? Using a conservative sediment supply rate and a range of rates of sea level rise and subsidence, a physically based model of deltaic river sedimentation [Kim et al., 2009] predicts that approximately 700-1200 square kilometers of new land (exposed surface and in-channel freshwater habitat) could be built over a century (Figure 1).

  19. Arsenic in benthic bivalves of San Francisco Bay and the Sacramento/San Joaquin River Delta

    USGS Publications Warehouse

    Johns, C.; Luoma, S.N.

    1990-01-01

    Arsenic concentrations were determined in fine-grained, oxidized, surface sediments and in two benthic bivalves, Corbicula sp. and Macoma balthica, within San Francisco Bay, the Sacramento/San Joaquin River Delta, and selected rivers not influenced by urban or industrial activity. Arsenic concentrations in all samples were characteristic of values reported for uncontaminated estuaries. Small temporal fluctuations and low arsenic concentrations in bivalves and sediments suggest that most inputs of arsenic are likely to be minor and arsenic contamination is not widespread in the Bay.

  20. Dispersion mechanisms of a tidal river junction in the Sacramento–San Joaquin Delta, California

    DOE PAGES

    Gleichauf, Karla T.; Wolfram, Philip J.; Monsen, Nancy E.; Fringer, Oliver B.; Monismith, Stephen G.

    2014-12-17

    In 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 Dopplermore » 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). Thus, 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 changing the junction flow phasing.« less

  1. Dispersion mechanisms of a tidal river junction in the Sacramento–San Joaquin Delta, California

    SciTech Connect

    Gleichauf, Karla T.; Wolfram, Philip J.; Monsen, Nancy E.; Fringer, Oliver B.; Monismith, Stephen G.

    2014-12-17

    In 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). Thus, 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 changing the junction flow phasing.

  2. Modern Pearl River Delta and Permian Huainan coalfield, China: A comparative sedimentary facies study

    USGS Publications Warehouse

    Suping, P.; Flores, R.M.

    1996-01-01

    Sedimentary facies types of the Pleistocene deposits of the Modern Pearl River Delta in Guangdong Province, China and Permian Member D deposits in Huainan coalfield in Anhui Province are exemplified by depositional facies of anastomosing fluvial systems. In both study areas, sand/sandstone and mud/mudstone-dominated facies types formed in diverging and converging, coeval fluvial channels laterally juxtaposed with floodplains containing ponds, lakes, and topogenous mires. The mires accumulated thin to thick peat/coal deposits that vary in vertical and lateral distribution between the two study areas. This difference is probably due to attendant sedimentary processes that affected the floodplain environments. The ancestral floodplains of the Modern Pearl River Delta were reworked by combined fluvial and tidal and estuarine processes. In contrast, the floodplains of the Permian Member D were mainly influenced by freshwater fluvial processes. In addition, the thick, laterally extensive coal zones of the Permian Member D may have formed in topogenous mires that developed on abandoned courses of anastomosing fluvial systems. This is typified by Seam 13-1, which is a blanket-like body that thickens to as much as 8 in but also splits into thinner beds. This seam overlies deposits of diverging and converging, coeval fluvial channels of the Sandstone D, and associated overbank-floodplain deposits. The limited areal extent of lenticular Pleistocene peat deposits of the Modern Pearl River Delta is due to their primary accumulation in topogenous mires in the central floodplains that were restricted by contemporaneous anastomosing channels.

  3. Measurement comparison of gas phase pollutants during field campaign in Pearl River Delta, China

    NASA Astrophysics Data System (ADS)

    Shao, M.; Zeng, L.; Hu, M.; Zhang, Y.

    2005-12-01

    Pearl River delta, an economically developed region in Guangdong province China, has been suffering from serious ground-level ozone pollution. To understand the formation mechanisms of the photochemical smog in this area, a field measurement campaign involving 12 separate institutes, was performed from Oct. 1 to Nov. 4, 2004. Measurements of gas phase pollutants, performed by the different research groups using several different methods, were inter-compared. Ambient SO2, O3 and NO were measured by Peking University and Hong Kong Polytechnic University using the same methods: chemiluminescence for NOx, pulsed fluorescence for SO2, and UV photometric method for O3. VOC speciation was accomplished using canister sampling followed by GC-MS measurement by Peking University and on-line GC-FID technology by National Central University in Taiwan. Ambient concentrations of HONO, the photolysis of which is the most important source of OH radical in Pearl River delta, was measured by two wet chemical methods: one from Energy Research Foundation of the Netherlands and one developed in Peking University. Based on these inter-comparisons, the co-variation of O3, NO and VOCs at an urban site and one rural site in Pearl River delta and estimates of the relative contributions to OH production from photolysis of O3, HONO and HCHO will be presented.

  4. Holocene evolution of the Song Hong (Red River) delta system, northern Vietnam

    NASA Astrophysics Data System (ADS)

    Tanabe, Susumu; Saito, Yoshiki; Lan Vu, Quang; Hanebuth, Till J. J.; Lan Ngo, Quang; Kitamura, Akihisa

    2006-05-01

    The Song Hong (Red River) delta, located on the western coast of the Gulf of Bac Bo (Tonkin) in the South China Sea, formed as a result of the Song Hong sediment discharge throughout the Holocene. The river's sedimentary basin upstream from the delta plain is not large. The delta plain comprises emerged tidal/mangrove flats formed during the sea-level highstand at + 2-3 m (6-4 cal. kyr BP) and a beach-ridge strandplain, with straight-to-lobate beach ridges, on the landward and seaward sides of the delta plain, respectively. The delta affords us the opportunity to examine river-mouth morphodynamics comprehensively in relation to sediment discharge and sea-level changes. In this paper, we describe the Holocene evolution of the Song Hong delta system and the river-mouth morphodynamics on the basis of seven sediment cores, each 30-70 m long, taken from the delta plain during 1999-2001 and 101 radiocarbon dates obtained from the core sediments. Sediments from the seven cores, consisting of incised-valley fills since the last glacial maximum, can be divided, in ascending order, into fluvial sediments composed of gravelly sand and mottled clay, tide-influenced estuarine sediments containing shell and wood fragments, and deltaic sediments composed of tide-influenced sand and mud deposits, in which the contents of sand and wood fragments increase upward. By applying sequence stratigraphic concepts, a transgressive surface can be identified at the gravelly sand-mottled clay boundary, and the maximum flooding surface can be identified at the estuarine-deltaic sediments boundary. The lowstand systems tract, transgressive systems tract, and highstand systems tract record ˜15, 15-9, and 9-0 cal. kyr BP, respectively. During the past 9 kyr, the majority of the sediment discharged by the Song Hong accumulated in the incised valley and enhanced progradation at the river mouth. The river mouth prograded from the bay head toward the gulf, and its morphology changed from funnel

  5. Chiral profiling of azole antifungals in municipal wastewater and recipient rivers of the Pearl River Delta, China.

    PubMed

    Huang, Qiuxin; Wang, Zhifang; Wang, Chunwei; Peng, Xianzhi

    2013-12-01

    Enantiomeric compositions and fractions (EFs) of three chiral imidazole (econazole, ketoconazole, and miconazole) and one chiral triazole (tebuconazole) antifungals were investigated in wastewater, river water, and bed sediment of the Pearl River Delta, South China. The imidazole pharmaceuticals in the untreated wastewater were racemic to weakly nonracemic (EFs of 0.450-0.530) and showed weak enantioselectivity during treatment in the sewage treatment plant. The EFs of the dissolved azole antifungals were usually different from those of the sorbed azoles in the suspended particulate matter, suggesting different behaviors for the enantiomers of the chiral azole antifungals in the dissolved and particulate phases of the wastewater. The azole antifungals were widely present in the rivers. The bed sediment was a sink for the imidazole antifungals. The imidazoles were prevalently racemic, whereas tebuconazole was widely nonracemic in the rivers. Seasonal effects were observed on distribution and chirality of the azole antifungals. Concentrations of the azole antifungals in the river water were relatively higher in winter than in spring and summer while the EF of miconazole in the river water was higher in summer. The mechanism of enantiomeric behavior of the chiral azole antifungals in the environment warrants further research.

  6. Connecting the historic 2011 Mississippi River flood to marsh sedimentation on the Delta

    NASA Astrophysics Data System (ADS)

    Lutken, C.; D'Emidio, M.; Falcini, F.; Horton, B. P.; Jerolmack, D. J.; Khan, N. S.; Li, C.; Macelloni, L.; McKee, K. L.

    2011-12-01

    The 2011 Mississippi River flood was arguably the largest in history. Although the massive inundation resulting from the flood was devastating for residents on the Delta, sediment carried to sea by the swollen river had the potential to combat wetland loss in some areas. There is currently much debate regarding how, and to what degree, sediment from the Mississippi and Atchafalaya Rivers contributes to maintaining and building fragile coastal marshes. This historic flood presented a rare and time-sensitive opportunity to determine the impact of a geologically-significant flood event on coastal sedimentation patterns and rates. We present a multi-disciplinary and multi-institutional effort to use the 2011 Mississippi flood to connect the dots between river dynamics, coastal dynamics, and marsh maintenance. We performed a coupled satellite analysis, boat survey and surface sediment sampling approach to characterize if and how sediments from this historic flood contributed to deposition and maintenance of Mississippi Delta coastal marshes. Sea surface temperature, height and color from satellite data have been used to track mixing and transport of river plume sediments; the boat survey measured the currents and sediment concentrations of the Mississippi plume in-situ during the peak of the flood; and a helicopter survey sampled marsh sediments after the flood subsided, allowing determination of flood-induced deposition rates and also sediment provenance. Preliminary results show that the Mississippi River injected sediment into the Gulf and did not contribute greatly to wetland development because of its narrow, focused jet. The Atchafalaya River plume spread diffusely across the landscape, and sediments reaching the sea were trapped within the coastal zone because the weak jet was incapable of penetrating the coastal current. Significant sedimentation occurred around the Atchafalaya, demonstrating that the flood contributed to wetland maintenance.

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

    PubMed

    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.

  8. Sediment infilling and wetland formation dynamics in an active crevasse splay of the Mississippi River delta

    USGS Publications Warehouse

    Cahoon, Donald R.; White, David A.; Lynch, James C.

    2011-01-01

    Crevasse splay environments provide a mesocosm for evaluating wetland formation and maintenance processes on a decadal time scale. Site elevation, water levels, vertical accretion, elevation change, shallow subsidence, and plant biomass were measured at five habitats along an elevation gradient to evaluate wetland formation and development in Brant Pass Splay; an active crevasse splay of the Balize delta of the Mississippi River. The processes of vertical development (vertical accretion, elevation change, and shallow subsidence) were measured with the surface elevation table–marker horizon method. There were three distinct stages to the accrual of elevation capital and wetland formation in the splay: sediment infilling, vegetative colonization, and development of a mature wetland community. Accretion, elevation gain, and shallow subsidence all decreased by an order of magnitude from the open water (lowest elevation) to the forest (highest elevation) habitats. Vegetative colonization occurred within the first growing season following emergence of the mud surface. An explosively high rate of below-ground production quickly stabilized the loosely consolidated sub-aerial sediments. After emergent vegetation colonization, vertical development slowed and maintenance of marsh elevation was driven both by sediment trapping by the vegetation and accumulation of plant organic matter in the soil. Continued vertical development and survival of the marsh then depended on the health and productivity of the plant community. The process of delta wetland formation is both complex and nonlinear. Determining the dynamics of wetland formation will help in understanding the processes driving the past building of the delta and in developing models for restoring degraded wetlands in the Mississippi River delta and other deltas around the world.

  9. Sediment infilling and wetland formation dynamics in an active crevasse splay of the Mississippi River delta

    NASA Astrophysics Data System (ADS)

    Cahoon, Donald R.; White, David A.; Lynch, James C.

    2011-08-01

    Crevasse splay environments provide a mesocosm for evaluating wetland formation and maintenance processes on a decadal time scale. Site elevation, water levels, vertical accretion, elevation change, shallow subsidence, and plant biomass were measured at five habitats along an elevation gradient to evaluate wetland formation and development in Brant Pass Splay; an active crevasse splay of the Balize delta of the Mississippi River. The processes of vertical development (vertical accretion, elevation change, and shallow subsidence) were measured with the surface elevation table-marker horizon method. There were three distinct stages to the accrual of elevation capital and wetland formation in the splay: sediment infilling, vegetative colonization, and development of a mature wetland community. Accretion, elevation gain, and shallow subsidence all decreased by an order of magnitude from the open water (lowest elevation) to the forest (highest elevation) habitats. Vegetative colonization occurred within the first growing season following emergence of the mud surface. An explosively high rate of below-ground production quickly stabilized the loosely consolidated sub-aerial sediments. After emergent vegetation colonization, vertical development slowed and maintenance of marsh elevation was driven both by sediment trapping by the vegetation and accumulation of plant organic matter in the soil. Continued vertical development and survival of the marsh then depended on the health and productivity of the plant community. The process of delta wetland formation is both complex and nonlinear. Determining the dynamics of wetland formation will help in understanding the processes driving the past building of the delta and in developing models for restoring degraded wetlands in the Mississippi River delta and other deltas around the world.

  10. Wetland loss due to land use change in the Lower Paraná River Delta, Argentina.

    PubMed

    Sica, Y V; Quintana, R D; Radeloff, V C; Gavier-Pizarro, G I

    2016-10-15

    Wetland loss is a global concern because wetlands are highly diverse ecosystems that provide important goods and services, thus threatening both biodiversity and human well-being. The Paraná River Delta is one of the largest and most important wetland ecosystems of South America, undergoing expanding cattle and forestry activities with widespread water control practices. To understand the patterns and drivers of land cover change in the Lower Paraná River Delta, we quantified land cover changes and modeled associated factors. We developed land cover maps using Landsat images from 1999 and 2013 and identified main land cover changes. We quantified the influence of different socioeconomic (distance to roads, population centers and human activity centers), land management (area within polders, cattle density and years since last fire), biophysical variables (landscape unit, elevation, soil productivity, distance to rivers) and variables related to extreme system dynamics (flooding and fires) on freshwater marsh conversion with Boosted Regression Trees. We found that one third of the freshwater marshes of the Lower Delta (163,000ha) were replaced by pastures (70%) and forestry (18%) in only 14years. Ranching practices (represented by cattle density, area within polders and distance to roads) were the most important factors responsible for freshwater marsh conversion to pasture. These rapid and widespread losses of freshwater marshes have potentially large negative consequences for biodiversity and ecosystem services. A strategy for sustainable wetland management will benefit from careful analysis of dominant land uses and related management practices, to develop an urgently needed land use policy for the Lower Delta. PMID:27369090

  11. Wetland loss due to land use change in the Lower Paraná River Delta, Argentina.

    PubMed

    Sica, Y V; Quintana, R D; Radeloff, V C; Gavier-Pizarro, G I

    2016-10-15

    Wetland loss is a global concern because wetlands are highly diverse ecosystems that provide important goods and services, thus threatening both biodiversity and human well-being. The Paraná River Delta is one of the largest and most important wetland ecosystems of South America, undergoing expanding cattle and forestry activities with widespread water control practices. To understand the patterns and drivers of land cover change in the Lower Paraná River Delta, we quantified land cover changes and modeled associated factors. We developed land cover maps using Landsat images from 1999 and 2013 and identified main land cover changes. We quantified the influence of different socioeconomic (distance to roads, population centers and human activity centers), land management (area within polders, cattle density and years since last fire), biophysical variables (landscape unit, elevation, soil productivity, distance to rivers) and variables related to extreme system dynamics (flooding and fires) on freshwater marsh conversion with Boosted Regression Trees. We found that one third of the freshwater marshes of the Lower Delta (163,000ha) were replaced by pastures (70%) and forestry (18%) in only 14years. Ranching practices (represented by cattle density, area within polders and distance to roads) were the most important factors responsible for freshwater marsh conversion to pasture. These rapid and widespread losses of freshwater marshes have potentially large negative consequences for biodiversity and ecosystem services. A strategy for sustainable wetland management will benefit from careful analysis of dominant land uses and related management practices, to develop an urgently needed land use policy for the Lower Delta.

  12. Migration patterns of Neolithic settlements on the abandoned Yellow and Yangtze River deltas of China

    NASA Astrophysics Data System (ADS)

    Chen, Zhongyuan; Zong, Yongqiang; Wang, Zhanghua; Wang, Hui; Chen, Jing

    2008-09-01

    Archaeological records of the Neolithic settlements on the eastern China coast between 35°N and 30°N, an area covering the abandoned Yellow River and the Yangtze River delta plains, reveal that Neolithic people moved from the Yellow River basin onto the northern coast for fishing, hunting and dry-land agriculture ~ 7000 yr ago. Marine transgression interrupted their activities on the low-lying (2-5 m in elevation) coastal wetlands between 6000 and 5000 yr ago, after which they reclaimed their land near the river mouths. Their migration routes on the southern Yangtze delta plain indicate another scenario: early Neolithic communities moved onto the plain for wet-rice cultivation. Despite relative sea-level rise from 7000 to 4000 yr ago, a large number of settlements were established on the lowlands between the eastern Chenier Ridges and the western Taihu Lake depression. The Chenier Ridges, with ~ 1.0 m higher topography than the adjacent coastal area, played a role in sheltering the Neolithic people. Subsequently, settlements waned considerably, possibly due to further marine inundation combined with cold climate. The present study shows that migration patterns of the Neolithic settlements are closely associated with a gradually rising sea level between 7000 and 4000 yr ago.

  13. Seasonal sediment transport and deposition in the Rajang River delta, Sarawak, East Malaysia

    NASA Astrophysics Data System (ADS)

    Staub, J. R.; Among, H. L.; Gastaldo, R. A.

    2000-06-01

    The Holocene Rajang River delta plain, which covers an area of 6500 km 2, has developed in a tropical, ever-wet climatic setting. Peat deposits, up to 15 m thick, occur in this delta plain. The tributary system to the delta is about 50,000 km 2 in area. Elevations exceed 2000 m in the drainage basin and hill slopes are steep. Rainfall in the region exceeds 370 cm/year, with highest rainfall levels or the "wet" season being coincident with the December-March monsoon. The monthly drainage-basin discharge is calculated to average about 3600 m 3/s, and the discharge normally ranges from 1000 to 6000 m 3/s. Spring tides in coastal areas range from 2.9 to 5.8 m. Tide data indicate that the tides are semidiurnal with a noticeable diurnal inequality. Vibracores recovered from bar forms in tidally influenced distributary channels contain laminated silts and sand-silt couplets that show evidence of rhythmic heterolithic stratification. Grain-size data indicate that these preserved delta plain siliciclastic sediments are the result of estuarine depositional processes that occur during intervals of reduced rainfall or the "dry" season (April-November). The number of laminae preserved per neap-spring cycle is the highest (≅18-20), and the average thickness is the greatest in the middle part of the delta plain. Distributary channels in this region normally contain low-salinity brackish water to freshwater. Vibracores recovered from delta front and prodelta sediments show evidence of heterolithic stratification, but rhythmicity is absent. Grain-size data indicate that preserved delta front and prodelta sediments are implaced by "wet" season processes (December-March) when fluvial flux and delta-plain erosion are at their maxima. Individual silt laminae and/or silt and sand interbeds are sometimes many centimeters thick, but average about 1 cm. These silt laminae and silt and sand interbeds or varves represent annual sedimentation events. These varves demonstrate that about 24

  14. Sea-Floor Mapping and Benthic Habitat GIS for the Elwha River Delta Nearshore, Washington

    USGS Publications Warehouse

    Cochrane, Guy R.; Warrick, Jonathan A.; Sagy, Yael; Finlayson, David; Harney, Jodi

    2008-01-01

    From March 1531, 2005, more than 252 km (19.5 km2) of seafloor offshore of the Elwha River Delta in the central Strait of Juan de Fuca was mapped by the USGS Coastal and Marine Geology Program. The purpose of this nearshore mapping was to (1) obtain high resolution bathymetry and acoustic reflectance properties of the seabed, (2) examine and record geologic characteristics of the seafloor, and (3) construct maps of sea-floor geomorphology and habitat. Substrate distribution was characterized with video-supervised statistical classification of the sonar data. Substrate of the survey was dominated by mixed sand-gravel and sand. Numerous boulder reefs were observed west of the river mouth within Freshwater Bay, whereas the sea-floor immediately adjacent to the river mouth was dominated by sand.

  15. Modern sediment characteristics and accumulation rates from the delta front to prodelta of the Yellow River (Huanghe)

    NASA Astrophysics Data System (ADS)

    Zhou, Liangyong; Liu, Jian; Saito, Yoshiki; Gao, Maosheng; Diao, Shaobo; Qiu, Jiandong; Pei, Shaofeng

    2016-08-01

    Since 1976, the main channel of the Yellow River (Huanghe) has been on the east side of the delta complex, and the river has prograded a broad new delta lobe in Laizhou Bay of the Bohai Sea. In 2012, extensive bathymetric and high-resolution seismic profiles were conducted and sediment cores were collected off the new delta lobe. This study examined delta sedimentation and morphology along a profile across the modern subaqueous Yellow River delta and into Laizhou Bay, by analyzing sediment radionuclides (137Cs, 210Pb and 7Be), sedimentary structure, grain-size composition, organic carbon content, and morphological changes between 1976 and 2012. The change in the bathymetric profile, longitudinal to the river's course, reveals subaqueous delta progradation during this period. The subbottom boundary between the new delta lobe sediment and the older seafloor sediment (before the 1976 course shift) was identified in terms of lithology and radionuclide distributions, and recognized as a downlap surface in the seismic record. The accumulation rate of the new delta lobe sediment is estimated to be 5-18.6 cm year-1 on the delta front slope, 2 cm year-1 at the toe of the slope, and 1-2 cm year-1 in the shelf areas of Laizhou Bay. Sediment facies also change offshore, from alternations of gray and brown sediment in the proximal area to gray bioturbated fine sediment in the distal area. Based on 7Be distribution, the shorter-term deposition rate was at least 20 cm year-1 in the delta front.

  16. Association between annual river flood pulse and paediatric hospital admissions in the Mekong Delta area.

    PubMed

    Phung, Dung; Huang, Cunrui; Rutherford, Shannon; Chu, Cordia; Wang, Xiaoming; Nguyen, Minh

    2014-11-01

    The Mekong Delta is the most vulnerable region to extreme climate and hydrological conditions however the association between these conditions and children's health has been little studied. We examine the association between annual river flood pulse and paediatric hospital admissions in a Vietnam Mekong Delta city. Daily paediatric hospital admissions (PHA) were collected from the City Paediatric Hospital, and daily river water level (RWL) and meteorological data were retrieved from the Southern Regional Hydro-Meteorological Centre from 2008 to 2011. We evaluated the association between annual river flood pulse (>=90th percentile of RWL) and PHA using the Poisson distributed lag model, controlling for temperature, relative humidity, day of week, seasonal and long-term trends. The seasonal pattern of PHA was examined using harmonic and polynomial regression models. The cumulative risk ratios estimated for a 15-day period following an extreme RWL was 1.26 (95%CI, 1.2-1.38) for all age groups, 1.27 (95%CI, 1.23-1.30) for under five-years and 1.15 (95%CI, 1.07-1.20) for school-aged children, 1.24 (95%CI, 1.21-1.27) for all-causes, 1.18 (95%CI, 1.12-1.21) for communicable infection, 1.66 (95%CI, 1.57-1.74) for respiratory infection and 1.06 (95%CI, 1.01-1.1) for other diseases. The peak PHA risk is in the September-October period corresponding to the highest RWL, and the PHA-RWL association was modified by temperature. An increase in PHA is significantly associated with annual river flood, and the pattern of PHA is seasonally correspondent to the RWL. These findings combined with projected changes in climate conditions suggest important implications of climate change for human health in the Mekong Delta region. PMID:25282279

  17. Association between annual river flood pulse and paediatric hospital admissions in the Mekong Delta area.

    PubMed

    Phung, Dung; Huang, Cunrui; Rutherford, Shannon; Chu, Cordia; Wang, Xiaoming; Nguyen, Minh

    2014-11-01

    The Mekong Delta is the most vulnerable region to extreme climate and hydrological conditions however the association between these conditions and children's health has been little studied. We examine the association between annual river flood pulse and paediatric hospital admissions in a Vietnam Mekong Delta city. Daily paediatric hospital admissions (PHA) were collected from the City Paediatric Hospital, and daily river water level (RWL) and meteorological data were retrieved from the Southern Regional Hydro-Meteorological Centre from 2008 to 2011. We evaluated the association between annual river flood pulse (>=90th percentile of RWL) and PHA using the Poisson distributed lag model, controlling for temperature, relative humidity, day of week, seasonal and long-term trends. The seasonal pattern of PHA was examined using harmonic and polynomial regression models. The cumulative risk ratios estimated for a 15-day period following an extreme RWL was 1.26 (95%CI, 1.2-1.38) for all age groups, 1.27 (95%CI, 1.23-1.30) for under five-years and 1.15 (95%CI, 1.07-1.20) for school-aged children, 1.24 (95%CI, 1.21-1.27) for all-causes, 1.18 (95%CI, 1.12-1.21) for communicable infection, 1.66 (95%CI, 1.57-1.74) for respiratory infection and 1.06 (95%CI, 1.01-1.1) for other diseases. The peak PHA risk is in the September-October period corresponding to the highest RWL, and the PHA-RWL association was modified by temperature. An increase in PHA is significantly associated with annual river flood, and the pattern of PHA is seasonally correspondent to the RWL. These findings combined with projected changes in climate conditions suggest important implications of climate change for human health in the Mekong Delta region.

  18. Morphodynamics and Sedimentology of a Falling Stage Sandy Fjord Delta, Goose River, Labrador

    NASA Astrophysics Data System (ADS)

    Slingerland, R.; Edmonds, D. A.; Parsons, D. R.; Best, J. L.; Royce, J.; Burpee, A.; Cederberg, J.; Caldwell, R.; Nijhuis, A.; McGuffin, A.

    2012-12-01

    Sediment size and degree of cohesion are thought to exert a strong control on the morphodynamic processes, planform shape and clinoform stratigraphy of deltas. To test model predictions concerning these two parameters, we present a morphometric and stratigraphic analysis of a sandy delta formed where the Goose River flows into Goose Bay at the western end of Lake Melville, Labrador. Goose River delta sediments consist of arkosic, heavy-mineral-rich sand (D50 = 225 to 600 microns) with very little silt and clay, placing this delta at the coarser-grained, non-cohesive end of the spectrum. The delta started to form approx. 7000 years ago as the Laurentide ice sheet retreated and post-glacial rebound created a relative base level fall of approximately 4 mm/yr. The current tidal range in Goose Bay averages 0.5 m, and the average wave height is negligible. Results from our 2012 field season show that the delta planform consists of two moribund lobes at elevations of ~ 5 m and ~ 2 m and a presently active delta at sea level. Aerial photography from 1951 to 2012 show there has been surprisingly little progradation despite active channel change at the six-month timescale and an assumed base level fall of 244 mm during that period. A topographic section along a dipline consists of three treads and two clinoform risers. The bottomset tread is a virtually featureless fjord bottom at ~35 m from which a first clinoform rises to a second tread at ~-15 m. The second tread is a sandy platform onto which an upper clinoform downlaps. This upper sandy clinoform ranges in dip from 9 to 17 dg. and passes into the topset at an elevation of ~ -1 m. The topset consists of braid-like trapezoidal unit bars that in GPR show little evidence of wave, alongshore current, or ice reworking, even though they are submerged at higher high tides. The planform, bar geometries and facies, and clinoform dips and dip-directions are remarkably consistent with model predictions from Delft3d.

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

    USGS Publications Warehouse

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

    2016-01-01

    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

  20. Geochemical Flows of Heavy Metals in Aquatic Systems of the Volga River Delta

    NASA Astrophysics Data System (ADS)

    Lychagin, Mikhail; Tkachenko, Anna; Kasimov, Nikolay

    2014-05-01

    The paper presents the results of the long-term environmental-geochemical studies of aquatic systems of the Volga River mouth area. It occupies a special place among the world's largest river deltas. The strong interest of researchers from different fields of science in the problems of the Volga River delta is associated with the high rate of periodic fluctuations of the Caspian Sea level, and also many factors of the technogenic geochemical impact on the aquatic systems. They range from the local impact of pollution sources in the delta to the regional impact of pollution sources located upstream. Aquatic systems of the Volga delta are highly diverse in morphology, hydrodynamic regime, lithology, sediments, and biota. This diversity determines the considerable spatial and temporal variability of the conditions of migration of heavy metals (HM) and other chemical elements. The study showed that the present contamination of the aquatic systems is manifested mainly in excess of heavy metals (Cu, Pb, Cd) in suspended matter over the global background values, most notably, in the flood period. In general the content of HM in the water and sediments during the last decades remains low; pollution of the bottom sediments is largely insignificant and of local character. We have identified the significant role of the water plants due to migration and accumulation of heavy metals in the shallow near-shore zones. Higher aquatic plants may serve as biogeochemical indicators of aquatic systems pollution. The metal content in macrophytes varies substantially depending on the ecological and morphological characteristics of species, as well as on conditions of their habitat. The difference between the minimal and maximal HM content may reach two to three orders of magnitude. Thickets of hornweed (Ceratophyllum demersum) and of other macrophytes in the mouths of the watercourses at the near-shore mouth area play the role of the biofilters precipitating a significant part of the

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

    PubMed

    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.

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

    PubMed

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

    2013-02-01

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

  3. Distribution of alkylphenols in the Pearl River Delta and adjacent northern South China Sea, China.

    PubMed

    Chen, Bing; Duan, Jing-Chun; Mai, Bi-xian; Luo, Xiao-Jun; Yang, Qing-Shu; Sheng, Guo-Ying; Fu, Jia-Mo

    2006-04-01

    The occurrence of alkylphenols (APs) was investigated in surface water and sediments from the Pearl River Delta and adjacent northern South China Sea. Most of the water samples contained detectable amounts of APs, ranging up to 0.628 microg l(-1) for nonylphenol (NP) and 0.068 microg l(-1) for octylphenol (OP). APs were found in all of the sediment samples with concentrations ranging from 59 to 7808 microg kg(-1) for NP and from 1 to 93 microg kg(-1) for OP. The Zhujiang River showed the highest concentrations of APs in both water and sediments. Significant decrease of APs concentrations going from the Zhujiang River to the Shiziyang River was observed. The Xijiang River contained concentrations of APs slightly higher in water but relatively lower in sediments than the Lingding Bay, which might be attributed to their different hydrodynamic and sedimentary characteristics. There was a decreasing trend of APs in water from the rivers to the estuary and further to the sea on the whole. In the Lingding Bay and its outer waters, concentrations of APs in sediments increased to a maximum and then decrease seaward, which was consistent with the distribution trend of the sediment organic carbon contents. Linear regression analyses showed the concentrations of APs were markedly correlated with the sediment organic carbon contents, indicating that the sediment organic carbon is an important factor controlling the levels of APs in sediments.

  4. Endocrine-disrupting chemicals in the Pearl River Delta and coastal environment: sources, transfer, and implications.

    PubMed

    Xu, Weihai; Yan, Wen; Huang, Weixia; Miao, Li; Zhong, Lifeng

    2014-12-01

    A study was conducted to investigate the occurrence and behavior of six endocrine-disrupting chemicals (EDCs) in sewage, river water, and seawater from the Pearl River Delta (PRD). The six EDCs under study were 4-nonylphenol (NP), bisphenol A (BPA), 17α-ethynylestradiol (EE2), estrone (E2), 17β-estradiol (E2), and estriol (E3). These EDCs, predominated by BPA, were found in high levels in the influents and the effluents of sewage treatment plants in the area. The relatively high concentrations (0.23-625 ng/L) of the EDCs detected in the receiving river water suggested that the untreated sewage discharge was a major contributor. The EDCs detected in eight outlets of the Pear River and the Pear River Estuary were in the ranges of 1.2-234 and 0.2-178 ng/L, respectively. The estrogen equivalents in the aquatic environments under study ranged from 0.08 to 4.5 ng/L, with E1 and EE2 being the two predominant contributors. As the fluxes of the EDCs from the PRD region to the nearby ocean are over 500 tons each year, the results of this study point to the potential that Pearl River is a significant source of the EDCs to the local environment there.

  5. On the control of climate- and human-modulated fluvial sediment delivery on river delta development: The Indus

    NASA Astrophysics Data System (ADS)

    Giosan, L.; Clift, P. D.; Blusztajn, J.; Tabrez, A.; Constantinescu, S.; Filip, F.

    2006-12-01

    Deltas are particularly vulnerable coasts, affected by changes in both continental and coastal ocean processes. The currently accelerated loss of deltaic lands across the world is primarily due to fluvial sediment starvation following the pandemic construction of river dams and water diversions. However, the influence on deltas of human- or even climate-modulated changes in fluvial sediment discharge has been studied less comprehensively than other controls e.g., the sea-level rise. We examined the Indus delta to understand how the sediment source (i.e., available fluvial sediment) has affected the development of the sediment sink (i.e., the subaerial and subaqueous delta evolution). With an elevated topography and generally arid climate in the watershed, the Indus has been, in natural conditions (i.e., before dams reduced its flow and sediment discharge by over 80%), one of the most important sediment-producing rivers in the world. Bathymetric data show that the Indus shelf morphology exhibits a compound clinoform morphology. Whereas the inner shoreface-connected clinoform has clearly developed as the subaqueous part of the modern Indus delta, the offshore clinoform is either a relict or a contemporaneous prodelta clinoform. Following the reduction in sediment discharge after the late 1950's, the deltaic shoreline in the central part of the delta coast started to recede providing sediment for the southeastern and northwestern coast sectors that remained largely progradational. This differential behavior of the delta shoreline indicates that even a drastic loss of fluvial sediment is initially buffered by an erosional smoothing of the delta coast. New data from onland drilling shows that unlike most Holocene deltas, the Indus delta prograded through the later part of the deglacial sea level rise, starting no later than 12,000 cal. years BP. Neodymium isotope data indicate that sediments comprising the entire Holocene delta originated predominantly in the monsoon

  6. Beach morphodynamics of the mixed grain-size delta of the dammed Elwha River, Washington

    NASA Astrophysics Data System (ADS)

    Warrick, J. A.; Gelfenbaum, G. R.; George, D. A.; Ruggiero, P.; Kaminsky, G. M.; Beirne, M.; Miller, I. M.

    2009-12-01

    Sediment supply provides a fundamental control on the morphology of river deltas, and humans have significantly modified these supplies for centuries. Here we examine the effects of almost a century of sediment supply reduction from the damming of the Elwha River in Washington on shoreline position and beach morphology of its wave-dominated delta. The mean rate of shoreline erosion during 1939-2006 is ~0.6 m/yr. Shoreline change and morphology differ spatially, however. Negligible shoreline change has occurred updrift (west) of the river mouth, where the beach is mixed sand to cobble, cuspate, and reflective. The beach downdrift (east) of the river mouth has had significant and persistent erosion, but this beach differs in that it has a reflective foreshore with a dissipative low-tide terrace. Erosion of the downdrift beach results from foreshore retreat, which broadens the low-tide terrace with time, and the rate of this kind of erosion has increased significantly from ~0.8 m/yr during 1939-1990 to ~1.4 m/yr during 1990-2006. Erosion rates for the downdrift beach derived from 2004-2007 topographic surveys vary between 0 and 13 m/yr, with an average of 3.8 m/yr. The 2004-2007 surveys also show that most erosion occurs during the winter with lower rates of change in the summer. We note that the low-tide terrace is significantly coarser (mean grain size ~100 mm) than the foreshore (mean grain size ~30 mm), a pattern contrary to the typical observation of fining low-tide terraces in the region and worldwide. Because this cobble low-tide terrace is created by foreshore erosion, has been steady over intervals of at least years, is predicted to have negligible longshore transport compared to the foreshore portion of the beach, and is inconsistent with oral history of abundant shellfish collections from the low-tide beach, we suggest that it is an armored layer of cobble clasts that are not generally competent in the physical setting of the delta. Thus, the cobble low

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

    USGS Publications Warehouse

    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

  8. Environmental Assessments in the Riparian Corridor of the Colorado River Delta

    NASA Technical Reports Server (NTRS)

    2001-01-01

    We will develop remote sensing methods to conduct environmental assessments in the riparian corridor of the Colorado River delta, shared by the United States and Mexico. This important regional ecosystem is dependent upon US water flows, yet the most important wildlife habitats are in Mexico. The delta region is poorly known and difficult to monitor on the ground. We will use ground-validated, aerial and satellite methods to develop accurate vegetation and habitat maps and predictive hydrological and vegetation models of this ecosystem in response to US flood releases. The work products will advance our understanding of water resource issues in dryland climates and provide a specific application tool for a critical binational natural resource area.

  9. Antibiotics in riverine runoff of the Pearl River Delta and Pearl River Estuary, China: concentrations, mass loading and ecological risks.

    PubMed

    Xu, Weihai; Yan, Wen; Li, Xiangdong; Zou, Yongde; Chen, Xiaoxiang; Huang, Weixia; Miao, Li; Zhang, Ruijie; Zhang, Gan; Zou, Shichun

    2013-11-01

    Ten antibiotics belonging to three groups (macrolides, fluoroquinolones and sulfonamides) were investigated in riverine runoff of the Pearl River Delta (PRD) and Pearl River Estuary (PRE), South China for assessing the importance of riverine runoff in the transportation of contaminants from terrestrial sources to the open ocean. All antibiotics were detected in the eight outlets with concentrations ranging from 0.7 to 127 ng L(-1). The annual mass loadings of antibiotics from the PRD to the PRE and coast were 193 tons with 102 tons from the fluoroquinolone group. It showed that antibiotics decreased from the riverine outlets to the PRE and open ocean. Risk assessment showed that most of these antibiotics showed various ecological risks to the relevant aquatic organisms, in which ofloxacin (OFL), erythromycin (ETM) and ciprofloxacin (CIP) posed high ecological risks to the studied aquatic environments.

  10. Hydraulic Survey and Scour Assessment of Bridge 524, Tanana River at Big Delta, Alaska

    USGS Publications Warehouse

    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.

  11. Environmental change in the Yangtze River delta since 12,000 years B.P.

    NASA Astrophysics Data System (ADS)

    Liu, Kam-Biu; Sun, Shuncai; Jiang, Xinhe

    1992-07-01

    A 52-m core from Qidong at the tip of the Yangtze River (Chang Jiang) delta provides a history of sea-level change, deltaic development, and vegetational and climatic changes during the last 12,000 yr. About 12,000 yr ago, when sea level was about 60 m below the present level, the coring site was situated in the innermost part of the exposed continental shelf. The late-Pleistocene vegetation on the uplands of the Lower Yangtze River valley was a mixed forest of deciduous and broadleaved evergreen trees in which Betula, Ulmus, Tsuga, and Cupressaceae were slightly more abundant than at present. Abies and Picea were probably present as relict populations on mountains bordering the region. Rapidly rising sea level converted the Qidong area to a coastal or estuarine environment between 11,000 and 10,800 yr B.P., leading to widespread development of wetlands dominated by Gramineae and Cyperaceae. During the next 2500 yr coastal erosion due to marine transgression obliterated the sedimentary record. Deltaic sedimentation predominated from 8300 to 3800 yr B.P., as the Yangtze River delta prograded by successively building a series of estuarine sand bars. During the mid-Holocene, the climate was slightly warmer and more humid than at present, allowing the subtropical broadleaved evergreen trees to increase their populations. Pinus and Quercus became more abundant after 3800 yr B.P. in response to climatic cooling. The present deltaic plain in Qidong formed less than 200 yr ago.

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

    PubMed

    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.

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

    USGS Publications Warehouse

    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.

  14. Refining the link between the Holocene development of the Mississippi River Delta and the geologic evolution of Cat Island, MS: implications for delta-associated barrier islands

    USGS Publications Warehouse

    Miselis, Jennifer L.; Buster, Noreen A.; Kindinger, Jack G.

    2014-01-01

    The geologic evolution of barrier islands is profoundly influenced by the nature of the deposits underlying them. Many researchers have speculated on the origin and evolution of Cat Island in Mississippi, but uncertainty remains about whether or not the island is underlain completely or in part by deposits associated with the past growth of the Mississippi River delta. In part, this is due to a lack of comprehensive geological information offshore of the island that could augment previous stratigraphic interpretations based on terrestrial borings. An extensive survey of Cat Island and its surrounding waters was conducted, including shallow-water geophysics (e.g., high-resolution chirp seismic, side-scan sonar, and swath and single-beam bathymetry) and both terrestrial and marine vibracoring. High-resolution seismic data and vibracores from south and east of the island show two horizontally laminated silt units; marine radiocarbon dates indicate that they are St. Bernard delta complex (SBDC) deposits. Furthermore, seismic data reveal that the SBDC deposits taper off toward the southern shoreline of Cat Island and to the west, morphology consistent with the distal edge of a delta complex. The sedimentology and extent of each unit suggest that the lower unit may have been deposited during an earlier period of continuous river flow while the upper unit may represent reduced or sporadic river flow. OSL dates from the island platform (beneath beach ridge complexes) indicate three stages of terrestrial evolution: island emergence resulting from relative sea-level rise (~ 5400 ybp) island aggradation via littoral transport (~ 2500–4000 ybp) and island degradation due to delta-mediated changes in wave direction (present– ~ 3600 ybp). Finally, the combination of terrestrial and marine data shows that portions of Cat Island that are lower in elevation than the central part of the island are younger and are likely underlain by a thin layer of deltaic sediments. This

  15. Epidemiology of multiple sclerosis in western Herzegovina and Herzegovina--Neretva Canton, Bosnia and Herzegovina.

    PubMed

    Klupka-Sarić, Inge; Galić, Marijana

    2010-03-01

    The aim of this study was to investigate the selected indicators of multiple sclerosis (MS) in Herzegovina (Western Herzegovina Canton and Herzegovina-Neretva Canton). By using all available health and medical sources in the studied area and using McDonald's criteria, a total of 96 patients were identified in the period from 1996 to 2006. Results of the study show that the crude prevalence of MS was 30.99/100,000 (95% confidence interval [CIC 24.8-37.2), the highest one in the municipality of Posusje (49.6/100,000) and the lowest one in the municipalities of Neum and Ravno (no recorded cases); the female/male ratio was 1.5; the mean age of the patients on the prevalence day was 41.4 +/- 10.2 years and the mean age at the disease onset was 30.7 +/- 6.4 years; the most often clinical course of the disease was relapsing-remitting (58%), secondary progressive course was present in 28% patients, primary progressive in 9% and progressive relapsing in 1% of patients; the most frequent initial signs of the disease were motor (33%) and sensory ones (24%). According to the results of the study, the south-western part of Bosnia and Herzegovina is an area on the crossing from moderate risk to high risk zone for MS. The distribution of MS is heterogeneous. MS was more prevalent in the municipalities with colder climate and more winter precipitation and it is not present in the coastal region with warmer climate and almost without winter precipitation.

  16. Sediment-hosted contaminants and distribution patterns in the Mississippi and Atchafalaya River Deltas

    USGS Publications Warehouse

    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

  17. Sediment facies, depositional environments, and distribution of phytoclasts in the recent Mahakam River delta, Kalimantan, Indonesia

    SciTech Connect

    Gastaldo, R.A. ); Huc, A.Y. )

    1992-12-01

    The Mahakam River delta is a tide- and wave-dominated delta located on the edge of the Kutei basin, eastern Kalimantan, Borneo. It is a coastal deltaic sequence, Neogene to Holocene in age, from which all recoverable hydrocarbons (crude oil and natural gas) are considered to be derived from kerogen III predecessors. However, a complete understanding of the types of sediments sourcing the hydrocarbons has not yet been achieved. A vibracoring program sampled the principal fine-grained depositional environments in two transects; one within the fluvially-dominated regime, one within the tidally-dominated regime. Ten sedimentary facies are distinguished and phytoclasts have been recovered from all environments of deposition. Canopy parts from the mixed tropical forest community are preserved throughout the delta, whereas dicotyledonous angiosperm mangroves are restricted to the subtidal zone and delta front. Nypa parts are preserved in most depositional environments. In sites where there appears to be an absence of macrodetritus, dispersed cuticle is recoverable. Identifiable plant parts include wood and fibrous tissues, Nypa petioles and leaf laminae, dicotyledonous angiosperm leaves and isolated cuticles, fruits and seeds, roots and rootlets, and moss. Dammar is found either as dispersed resin ducts or amorphous clasts. Additional biotic components found in bedded plant litters include insects, gastropods, bivalves, sand dollars, ostracods, and crabs. Fluvial channels and depositional sites associated with these systems in the delta front can be differentiated from Nypa swamps and mixed tropical hardwood-palm swamps based on their phytological components and accessory biotic elements. 39 refs., 10 figs., 3 tabs.

  18. LANDSCAPE ECOLOGY ASSESSMENT OF THE TENSAS RIVER BASIN, MISSISSIPPI RIVER DELTA REGION, AND GULF OF MEXICO

    EPA Science Inventory

    A group of landscape ecological indicators were applied to biophysical data masked to the Tensas River Basin. The indicators were use to identify and prioritize sources of nutrients in a
    Mississippi River System sub-basin. Remotely sensed data were used for change detection a...

  19. Nesting ecology of Spectacled Eiders Somateria fischeri on the Indigirka River Delta, Russia

    USGS Publications Warehouse

    Pearce, J.M.; Esler, Daniel; Degtyarev, A.G.

    1998-01-01

    In 1994 and 1995 we investigated breeding biology and nest site habitat of Spectacled Eiders on two study areas within the coastal fringe of the Indigirka River Delta, Russia (71??20' N, 150??20' E). Spectacled Eiders were first observed on 6 June in both years and nesting commenced by mid-June. Average clutch size declined with later nest initiation dates by 0.10 eggs per day; clutches were larger in 1994 than 1995 and were slightly larger on a coastal island study area compared to an interior area. Nesting success varied substantially between years, with estimates of 1.6% in 1994 and 27.6% in 1995. Total egg loss, through avian or mammalian predation, occurred more frequently than partial egg loss. Partial egg loss was detected in 16 nests and appeared unrelated to nest initiation date or clutch size. We found no difference among survival rates of nests visited weekly, biweekly, and those at which the hen was never flushed, suggesting that researcher presence did not adversely affect nesting success. A comparison of nine habitat variables within each study area revealed little difference between nest sites and a comparable number of randomly located sites, leading us to conclude that Spectacled Eiders nest randomly with respect to most small scale habitat features. We propose that large scale landscape features are more important indicators of nesting habitat as they may afford greater protection from land-based predators, such as the Arctic Fox. Demographic data collected during this study, along with recent conservation measures implemented by the Republic of Sakha (Yakutia), lead us to conclude that there are few threats to the Indigirka River Delta Spectacled Eider population. Presently, the Indigirka River Delta contains the largest concentration of nesting Spectacled Eiders and deserves continued monitoring and conservation.

  20. Epidemiological investigation of Clonorchis sinensis infection in freshwater fishes in the Pearl River Delta.

    PubMed

    Chen, Daixiong; Chen, Jieyun; Huang, Ji; Chen, Xueying; Feng, Dana; Liang, Baofang; Che, Yuchuan; Liu, Xiaodan; Zhu, Cuihua; Li, Xiaomin; Shen, Haoxian

    2010-09-01

    Pearl River Delta region is a high clonorchiasis-endemic area in China. However, no complete epidemiological data exist regarding its infection in freshwater fishes, an important epidemic factor for Clonorchis sinensis. The present study collected freshwater fishes and shrimps from 32 sites of nine cities in the Pearl River Delta, and the encysted metacercariae of C. sinensis were detected by digesting these specimens with artificial gastric juice. The mean infection rate of freshwater fishes was 37.09% (2,160/5,824) with a mean number of 14.269 encysted metacercariae in every infected fish and 0.460 encysted metacercariae in every gram of fish meat. Of these freshwater fishes, 5,219 were domesticated, and the infection rate was 36.69% with a mean number of 10.743 encysted metacercariae in every infected fish and 0.312 encysted metacercariae in every gram of fish meat; the other 605 were wild, and the infection rate was 40.50% with a mean number of 41.829 encysted metacercariae in every infected fish and 8.812 encysted metacercariae in every gram of fish meat. A total of 228 shrimps were examined, and 3.07% of them were infected with a mean number of 1.00 encysted metacercariae in every infected shrimp. Pseudorasbora parva and Ctenopharyngodon idellus had the highest infection rate and degree of infection in the fishes studied. The results demonstrated a high incidence of C. sinensis infection in freshwater fishes and shrimps within Pearl River Delta region and a great difference in the infection rate among different collection sites and different fish species.

  1. [Regional distribution and ecological risk evaluation of heavy metals in surface sediments from coastal wetlands of the Yellow River Delta].

    PubMed

    Liu, Zhi-Jie; Li, Pei-Ying; Zhang, Xiao-Long; Li, Ping; Zhu, Long-Hai

    2012-04-01

    Characteristics of heavy metal distributions in surface sediments of different areas in the Yellow River Delta coastal wetland are analyzed, and the influences of sediment environment on heavy metal distributions are discussed. Heavy metal pollution and potential ecological risk in surface sediments of the Yellow River Delta coastal wetland are estimated by using Hakanson potential ecological risk (PER) factors method. The analyzed results indicate that the average contents of Hg, Cu, Pb, Zn, Cd and Cr are 0.034, 18.733, 19.393, 65.317, 0.235 and 62.940 microg x g(-1), respectively. The heavy metal distributions vary with regional environment changes. The accumulating index of heavy metals in the current outfall area is the highest of the three regions assigned by author,the second is that of the ancient Yellow River Delta in the north of Shandong province, and the lowest is that of the abandoned delta. Heavy metal distributions in the Yellow River Delta coastal wetland are affected significantly by hydrodynamic system. In addition, the content of clay in surface sediments plays an important role in the distribution and accumulation of heavy metals. The results also suggest that the heavy metal pollution in the Yellow River Delta coastal wetland is in a low pollution level, with a comprehensive pollution index varying from 0.10 to 4.14. And element Cr is the major pollution factor and its average of single pollution index is 0.63. The order of pollution extents of six typical pollutants is Cr > Cu > Zn > Cd > Pb > Hg. The comprehensive potential ecological risk index is between 0.46 and 51.88, indicating a low potential ecological risk. The order of potential ecological risk parameter is Cd > Hg > Cu > Cr > Pb > Zn. Element Cd is also the major factor of potential ecological risks in the Yellow River Delta coastal wetland.

  2. Mississippi River delta mudslides: techniques allow for continued development with reduced risk

    NASA Astrophysics Data System (ADS)

    Handley, Lawrence R.

    1982-09-01

    The Mississippi River delta environment provides all the necessary ingredients to make sediment instability a critical geohazard to be dealt with in a productive oil and gas region. Some of the early development has encountered problems with the unstable sediments as pipelines have been ruptured and platform foundations have been damaged. From experience and surveys, the government agencies and industry involved on the continental shelf are aware of the nature of instability, mechanism of movement, rate of movement and structural failure that can result, and are applying that knowledge to oil and gas exploration, development and to leasing and permitting.

  3. Nature of decadal-scale sediment accumulation on the western shelf of the Mississippi River delta

    NASA Astrophysics Data System (ADS)

    Reide Corbett, D.; McKee, Brent; Allison, Mead

    2006-11-01

    Sediment delivered to coastal systems by rivers (15×10 9 tons) plays a key role in the global carbon and nutrient cycles, as deltas and continental shelves are considered to be the main repositories of organic matter in marine sediments. The Mississippi River, delivering more than 60% of the total dissolved and suspended materials from the conterminous US, dominates coastal and margin processes in the northern Gulf of Mexico. Draining approximately 41% of the conterminous US, the Mississippi and Atchafalaya river system deliver approximately 2×10 8 tons of suspended matter to the northern Gulf shelf each year. Unlike previous work, this study provides a comprehensive evaluation of sediment accumulation covering majority of the shelf (<150 m water depth) west of the Mississippi Delta from 92 cores collected throughout the last 15 years. This provides a unique and invaluable data set of the spatial and modern temporal variations of the sediment accumulation in this dynamic coastal environment. Three types of 210Pb profiles were observed from short cores (15-45 cm) collected on the shelf. Proximal to Southwest Pass in 30-100 m water depths, non-steady-state profiles were observed indicating rapid accumulation. Sediment accumulation rates in this area are typically >2.5 cm yr -1 (>1.8 g cm -2 yr -1). Kasten cores (˜200 cm in length) collected near Southwest Pass also indicate rapid deposition (>4 cm yr -1; >3 g cm -2 yr -1) on a longer timescale than that captured in the box cores. Near shore (<20 m), profiles are dominated by sediments reworked by waves and currents with no accumulation (the exception is an area just south of Barataria Bay where accumulation occurs). The remainder of the shelf (distal of Southwest Pass) is dominated by steady-state accumulation beneath a ˜10-cm thick mixed layer. Sediment accumulation rates for the distal shelf are typically <0.7 cm yr -1 (<0.5 g cm -2 yr -1). A preliminary sediment budget based on the distribution of 210Pb

  4. Impacts of urbanization on river system structure: a case study on Qinhuai River Basin, Yangtze River Delta.

    PubMed

    Ji, Xiaomin; Xu, Youpeng; Han, Longfei; Yang, Liu

    2014-01-01

    Stream structure is usually dominated by various human activities over a short term. An analysis of variation in stream structure from 1979 to 2009 in the Qinhuai River Basin, China, was performed based on remote sensing images and topographic maps by using ArcGIS. A series of river parameters derived from river geomorphology are listed to describe the status of river structure in the past and present. Results showed that urbanization caused a huge increase in the impervious area. The number of rivers in the study area has decreased and length of rivers has shortened. Over the 30 years, there was a 41.03% decrease in river length. Complexity and stability of streams have also changed and consequently the storage capacities of river channels in intensively urbanized areas are much lower than in moderately urbanized areas, indicating a greater risk of floods. Therefore, more attention should be paid to the urban disturbance to rivers. PMID:25116497

  5. Impacts of urbanization on river system structure: a case study on Qinhuai River Basin, Yangtze River Delta.

    PubMed

    Ji, Xiaomin; Xu, Youpeng; Han, Longfei; Yang, Liu

    2014-01-01

    Stream structure is usually dominated by various human activities over a short term. An analysis of variation in stream structure from 1979 to 2009 in the Qinhuai River Basin, China, was performed based on remote sensing images and topographic maps by using ArcGIS. A series of river parameters derived from river geomorphology are listed to describe the status of river structure in the past and present. Results showed that urbanization caused a huge increase in the impervious area. The number of rivers in the study area has decreased and length of rivers has shortened. Over the 30 years, there was a 41.03% decrease in river length. Complexity and stability of streams have also changed and consequently the storage capacities of river channels in intensively urbanized areas are much lower than in moderately urbanized areas, indicating a greater risk of floods. Therefore, more attention should be paid to the urban disturbance to rivers.

  6. Dependence of flow and transport through the Williamson River Delta, Upper Klamath Lake, Oregon, on wind, river inflow, and lake elevation

    USGS Publications Warehouse

    Wood, Tamara M.

    2012-01-01

    The hydrodynamic model of Upper Klamath and Agency Lakes, Oregon, was used to run 384 realizations of a numerical tracer experiment in order to understand the relative effects of wind, lake elevation, and Williamson River inflow on flow and transport (the movement of water and passively transported constituents) through the Williamson River Delta. Significant findings from this study include: * The replacement rate of water increased in Tulana and Goose Bay with increasing lake elevation, Williamson River inflow, and wind speed. * The fraction of Williamson River inflow passing through either side of the Delta increased with lake elevation and Williamson River inflow. * The partial replacement rate of water in Goose Bay with water from the Williamson River increased with wind speed. * The partial replacement rate of water in Tulana with water from the Williamson River decreased with wind speed. * Strong wind forcing at the water surface caused more of the Williamson River inflow to pass through Goose Bay than through Tulana. * Westerly to northwesterly winds result in more of the Williamson River inflow passing through the Goose Bay side of the Delta than through the Tulana side. * Regression models developed from the tracer experiments can be used to quantify the dependencies between transport and the independent variables to obtain rough estimates of useful quantities such as residence time and steady-state solute concentrations.

  7. Spatial distribution and partition of perfluoroalkyl acids (PFAAs) in rivers of the Pearl River Delta, southern China.

    PubMed

    Liu, Baolin; Zhang, Hong; Xie, Liuwei; Li, Juying; Wang, Xinxuan; Zhao, Liang; Wang, Yanping; Yang, Bo

    2015-08-15

    This study investigated the occurrence of perfluoroalkyl acids (PFAAs) in surface water from 67 sampling sites along rivers of the Pearl River Delta in southern China. Sixteen PFAAs, including perfluoroalkyl carboxylic acids (PFCAs, C5-14, C16 and C18) and perfluoroalkyl sulfonic acids (PFSAs, C4, C6, C8 and C10) were determined by high performance liquid chromatography-negative electrospray ionization-tandem mass spectrometry (HPLC/ESI-MS/MS). Total PFAA concentrations (∑ PFAAs) in the surface water ranged from 1.53 to 33.5 ng·L(-1) with an average of 7.58 ng·L(-1). Perfluorobutane sulfonic acid (PFBS), perfluorooctanoic acid (PFOA), and perfluorooctane sulfonic acid (PFOS) were the three most abundant PFAAs and on average accounted for 28%, 16% and 10% of ∑ PFAAs, respectively. Higher concentrations of ∑ PFAAs were found in the samples collected from Jiangmen section of Xijiang River, Dongguan section of Dongjiang River and the Pearl River flowing the cities which had very well-developed manufacturing industries. PCA model was employed to quantitatively calculate the contributions of extracted sources. Factor 1 (72.48% of the total variance) had high loading for perfluorohexanoic acid (PFHxA), perfluoropentanoic acid (PFPeA), PFBS and PFOS. For factor 2 (10.93% of the total variance), perfluorononanoic acid (PFNA) and perfluoroundecanoic acid (PFUdA) got high loading. The sorption of PFCAs on suspended particulate matter (SPM) increased by approximately 0.1 log units for each additional CF2 moiety and that on sediment was approximately 0.8 log units lower than the SPM logKd values. In addition, the differences in the partition coefficients were influenced by the structure discrepancy of absorbents and influx of fresh river water. These data are essential for modeling the transport and environmental fate of PFAAs.

  8. Distribution, sources, and fluxes of heavy metals in the Pearl River Delta, South China.

    PubMed

    Geng, Junjie; Wang, Yiping; Luo, Hanjin

    2015-12-30

    Riverine samples were collected at various locations in the Pearl River Delta (PRD) to determine the concentrations of heavy metals (Cr, Ni, Cu, Mn, Zn, Cd, and Pb) in time and space and to estimate the fluxes of heavy metals to the coastal waters off South China. Most of the elements exhibit clear temporal and spatial trends. Principal component analysis shows that surface erosion is the major factor affecting metal concentrations in particulates in the PRD. Natural geology is an important source of these heavy metals. The annual fluxes of Cr, Ni, Cu, Mn, Zn, Cd, and Pb in upstream and downstream were 445, 256, 241, 3293, 1279, 12, and 317 t/year and 1823, 1144, 1786, 15,634, 6183, 74, and 2017 t/year, respectively. A comparison indicated that the annual fluxes of Mn accounted for 1.3% of the global river fluxes, whereas other elements contribute <1%. PMID:26555797

  9. Hydrogeochemical assessment of groundwater quality in a river delta using multivariate statistical techniques

    NASA Astrophysics Data System (ADS)

    Matiatos, Ioannis; Paraskevopoulou, Vasiliki; Botsou, Fotini; Dassenakis, Manolis; Lazogiannis, Konstantinos; Ghionis, George; Poulos, Serafim

    2016-04-01

    The knowledge of the factors controlling the regional groundwater quality regime is important for planning and management of the groundwater resources. This work applies conventional hydrogeochemical and multivariate statistical techniques to identify the main factors and mechanisms controlling the hydrogeochemistry of groundwater in the deltaic environment of River Pinios (Thessaly) as well as possible areas of interactions between groundwater and surface water bodies. Hierarchical Cluster Analysis (HCA) and Principal Components Analysis (PCA) are performed using a data set of physical-chemical parameters from surface water and groundwater sites. Through HCA the paper's objective is to group together surface water and groundwater monitoring sites based on similarities in hydrochemistry in order to indicate areas of groundwater-surface water interaction. On the other hand, PCA aims at indicating factors responsible for the hydrogeochemical characteristics of the water bodies in the river delta (e.g., water-rock interaction, seawater intrusion, anthropogenic activities).

  10. Functional Carbon Processing and Its Linkage to Hydrology in Lakes of the Mackenzie River Delta

    NASA Astrophysics Data System (ADS)

    Lesack, L.; Tank, S. E.; Gareis, J.; Chateauvert, C. A.; Squires, M.; Marsh, P.

    2011-12-01

    The circumpolar arctic contains a number of large river deltas that are lake-rich because of thermokarst effects. The Mackenzie Delta is the second largest, containing 45,000 lakes within a floodplain area 1/3rd the size of Switzerland. A 20-year case study has placed the biogeochemistry of these lakes into context via analysis of 40 years of water level records, river-to-lake connectivities, and estimates of annual river-water renewal. The lakes collectively represent gradients from turbid waters to transparent, high dissolved-nutrients to low, low total dissolved organic matter (DOM) to high, high chromophoric-DOM (CDOM) to low, high inorganic content of lake sediments to high organic sediment, and low under-water ultraviolet-irradiance to higher irradiances. Super imposed on these are biotic community production gradients respectively ranging from low production of aquatic bacteria to high, low macrophytes to high, low epiphyton to high, high phytoplankton and epipelon at intermediate flooding-frequencies, low small-bodied zooplankton to high large-bodied, high fish to no fish, and moderate aquatic birds to high. All the above correspond with a gradient of lake flooding regimes with average river-to-lake connection times ranging from >150 days per year in the lowest elevation lakes maintaining near continuous connection with the river over the open-water period to <4.5 days per year in the highest elevation lakes with long and variable disconnection periods from the river. Thermokarst lakes and lake-chain systems represent special cases where lake behaviors may depart from patterns otherwise strongly linked to river-to-lake connection times. Based on work in this system thus far, we propose a new conceptual model of overall carbon processing based on functional groups of organisms and abiotic processes that govern the overall balance between recycling of carbon to the atmosphere as CO2 or CH4, or the accumulation and storage of carbon in lake biomasses, and

  11. Water quality in select regions of Cauvery Delta River basin, southern India, with emphasis on monsoonal variation.

    PubMed

    Solaraj, Govindaraj; Dhanakumar, Selvaraj; Murthy, Kuppuraj Rutharvel; Mohanraj, Rangaswamy

    2010-07-01

    Delta regions of the Cauvery River basin are one of the significant areas of rice production in India. In spite of large-scale utilization of the river basin for irrigation and drinking purposes, the lack of appropriate water management has seemingly deteriorated the water quality due to increasing anthropogenic activities. To assess the extent of deterioration, physicochemical characteristics of surface water were analyzed monthly in select regions of Cauvery Delta River basin, India, during July 2007 to December 2007. Total dissolved solids, chemical oxygen demand, and phosphate recorded maximum levels of 1,638, 96, and 0.43 mg/l, respectively, exceeding the permissible levels at certain sampling stations. Monsoonal rains in Cauvery River basin and the subsequent increase in river flow rate influences certain parameters like dissolved solids, phosphate, and dissolved oxygen. Agricultural runoff from watershed, sewage, and industrial effluents are suspected as probable factors of water pollution. PMID:19496010

  12. Water quality in select regions of Cauvery Delta River basin, southern India, with emphasis on monsoonal variation.

    PubMed

    Solaraj, Govindaraj; Dhanakumar, Selvaraj; Murthy, Kuppuraj Rutharvel; Mohanraj, Rangaswamy

    2010-07-01

    Delta regions of the Cauvery River basin are one of the significant areas of rice production in India. In spite of large-scale utilization of the river basin for irrigation and drinking purposes, the lack of appropriate water management has seemingly deteriorated the water quality due to increasing anthropogenic activities. To assess the extent of deterioration, physicochemical characteristics of surface water were analyzed monthly in select regions of Cauvery Delta River basin, India, during July 2007 to December 2007. Total dissolved solids, chemical oxygen demand, and phosphate recorded maximum levels of 1,638, 96, and 0.43 mg/l, respectively, exceeding the permissible levels at certain sampling stations. Monsoonal rains in Cauvery River basin and the subsequent increase in river flow rate influences certain parameters like dissolved solids, phosphate, and dissolved oxygen. Agricultural runoff from watershed, sewage, and industrial effluents are suspected as probable factors of water pollution.

  13. Geoarchaeological research for Roman waterworks in the Rhine-Meuse river delta, the Netherlands

    NASA Astrophysics Data System (ADS)

    Verhagen, Jan; Kluiving, Sjoerd; van Leeuwen, Liz; Anker, Emiel

    2015-04-01

    It is known that Romans in the Low Countries at the northern margin of their empire were practicing diverse systems of water state management to maintain economic and above all strategic stability. In early Roman period Romans created a shipping route from the Rhine towards the north by digging canals and constructing dams. This was done in order to submit the northern part of Germania through the Waddenzee and the German rivers Eems, Weser and Elbe. During the middle Roman period the Romans had canceled their efforts to submit Germania. In that period we know the River Rhine as the limes, which not only was a borderline of the Roman empire, but can also be seen as a guarded transport route. The research area is situated in the eastern part of the Rhine-Meuse river valley/delta system. The area represents a highly dynamic geological history of erosion and deposition close to the river system's equilibrium point. In order to reconstruct the former landscape and investigate whether traces of Roman waterworks could be indicated or disproved geoarchaeological coring campaigns have been carried out with lithological, textural and palaeoecological analyses. The results of the research presented in this poster will be: 1) Assessment of the condition of the covered Pleistocene sediments in the area, 2) Identification of the buried gullies and levees in the vicinity of the remains of the Roman castellum 'Carvium ad molem', which should have been built at the bifurcation of the delta branches of Rhine and Waal, 3) Chronological control of gullies and levees, 4) Landscape reconstruction in different time periods. Finally based on the geoarchaeological results a comment will be made on the location of the Drusus dam in the study area, the landscape context of the castellum and its position on the apex of the Insula Batavorum.

  14. Hydrogeochemical characteristics of groundwater from the two main aquifers in the Red River Delta, Vietnam

    NASA Astrophysics Data System (ADS)

    Nguyen, Thuy Thanh; Kawamura, Akira; Tong, Thanh Ngoc; Nakagawa, Naoko; Amaguchi, Hideo; Gilbuena, Romeo

    2014-10-01

    In the Red River Delta, situated in the northern part of Vietnam, nearly its entire population depends solely on groundwater for daily water consumptions. For this reason, groundwater quality assessments must be carefully carried out using hydrogeochemical properties, to ensure effective groundwater resource planning for the Delta’s present and future groundwater use. In this study, the spatial and seasonal changes in the hydrogeochemical characteristics of groundwater in the two main aquifers of the RRD were investigated by analyzing the physicochemical data obtained in 2011 from 31 conjunctive wells in the Delta’s Holocene unconfined aquifer (HUA) and Pleistocene confined aquifer (PCA) using the Piper diagram and the Gibbs diagram. Results of the data analysis show that the groundwater in both aquifers in the upstream area of the delta is dominated by the [Ca2+-HCO3-] water-type, while the [Na+-Cl-] dominates along the middle-stream and downstream areas. Seasonal changes in the hydrogeochemical facies in both aquifers, comparing the results for the dry and the rainy seasons, were detected in about one third of the sampling wells, which were mainly located at the upstream portion of the Delta. The hydrogeochemical facies of HUA were different from that of PCA by about 45% of the sampling wells in both the dry and the rainy seasons, which were found mostly in the upstream and middle-stream areas.

  15. [Relationships between typical vegetations, soil salinity, and groundwater depth in the Yellow River Delta of China].

    PubMed

    Ma, Yu-Lei; Wang, De; Liu, Jun-Min; Wen, Xiao-Hu; Gao, Meng; Shao, Hong-Bo

    2013-09-01

    Soil salinity and groundwater depth are the two important factors affecting the vegetation growth and distribution in the Yellow River Delta. Through field investigation and statistical analysis, this paper studied the relationships between the typical vegetations (Suaeda heteroptera-Tamarix chinensis, Robinia pseudoacacia, Phragmites australis, and cotton) , soil salinity, and groundwater depth in the Delta. In the study area, groundwater depth had significant effects on soil salinity, with the average influence coefficient being 0.327. When the groundwater depth was 0.5-1.5 m, soil salinization was most severe. The vegetation growth in the Delta was poorer, with the NDVI in 78% of the total area being less than 0.4. Groundwater depth and soil salinity had significant effects on the vegetation distribution. Soil salinity had significant effects on the NDVI of R. pseudoacacia, S. heteroptera-T. chinensis, P. australis, and cotton, while groundwater depth had significant effects on the NDVI of S. heteroptera - T. chinensis, but lesser effects on the NDVI of P. australis, cotton and R. pseudoacacia.

  16. Environmental changes monitoring by remote sensing for Danube River Delta, Romania

    NASA Astrophysics Data System (ADS)

    Zoran, Maria

    2003-03-01

    Danube delta, one of the largest European wetlands left, lies predominantly in Romania, being considered a Biosphere Reservation. Environmental impact assessment and detection of spatio-temporal changes is needed for protection, conservation and restoration of the biological diversity specific to this area. Danube Delta wetlands and aquatic ecosystem are increasingly endangered by global or regional environmental changes due to the discharges or deposition of excess nutrients and/or harmful substances, to the reclamation of lands for agriculture, forestry, and engineering of water flows. A multitemporal data set consisting of LANDSAT MSS, TM and SAR-ERS1 images for Romanian Danube River Delta was used for comparing and mapping landcover change via change detection. The main aim of this paper is to conduct a comprehensive analysis based on existing historical and more recent data to establish the link between phytoplankton bloom development and related harmful phenomena in the North-Western part of Black Sea and changes in the Danube watershed (landuse, fertilizer utilization, waste water treatments). Based on satellite data were analyzed some test areas in the vicinity of the Danube mouths where the nutrient concentration were highest, being assimilated with an expected oxygen depletion, sulfate reduction and methanogenesis in the bottom waters and the superficial sediments.

  17. Detection of the Three Gorges Dam influence on the Changjiang (Yangtze River) submerged delta.

    PubMed

    Dai, Zhijun; Liu, James T; Wei, Wen; Chen, Jiyu

    2014-01-01

    While most large river-deltas in the world are facing the risk of subsidence and erosion in the Anthropocene, it is suspected that the Changjiang submerged delta (CSD) could be subjected to the impacts of the world's largest dam, the Three Gorges Dam (TGD). Here we firstly indicate that the CSD went through high accumulation (1958-1978); slight accumulation (1978-1997), slight erosion (1997-2002); and high accumulation (2002-2009), despite the 70% reduction of the sediment load from upstream since the operation of the TGD in 2003. Meanwhile, at the depocenter of the submerged delta, the accumulation maintained a high rate of 10 cm/yr during 1958-2009. This suggests on a longer term, the distal sediment source from the upstream had little effect on the CSD. Within this time frame the changes in the partition of sediment load among the branching channels of the Changjiang Estuary could likely control the shifting of the depocenter of the CSD on a decadal time scale. Episodic extreme floods and storm surges also increased the magnitude of deposition and erosion of the CSD on short-term scales. A re-evaluation of the impacts of TGD on the CSD is urgently needed. PMID:25321660

  18. Constraining rates and trends of historical wetland loss, Mississippi River Delta Plain, south-central Louisiana

    USGS Publications Warehouse

    Bernier, Julie C.; Morton, Robert A.; Barras, John A.

    2006-01-01

    The timing, magnitude, and rate of wetland loss were described for five wetland-loss hotspots in the Terrebonne Basin of the Mississippi River delta plain. Land and water areas were mapped for 34 dates between 1956 and 2004 from historical National Wetlands Inventory (NWI) datasets, aerial photographs, and Landsat Thematic Mapper (TM) satellite images. Since 1956, the emergent land area at the five study areas in south-central Louisiana has decreased by about 50%. Comparison of the water-area curve derived from the 29 TM images with water-level records from the nearby Grand Isle, Louisiana tide gauge (NOS #8761724) clearly shows that changes in land and water areas fluctuate in response to variations in regional water levels. The magnitude of water-area fluctuations decreased from the 1980s to the 1990s as former areas of wet marsh within and immediately adjacent to the wetland-loss hotspots became permanently submerged. The most rapid wetland loss occurred during the late 1960s and 1970s. Peak wetland-loss rates during this period were two to four times greater than both the pre-1970s background rates and the most recent wetland-loss rates. These results provide constraints on predicting future delta-plain wetland losses and identify Landsat TM imagery as an important source for analyzing land- and water-area changes across the entire delta plain.

  19. Detection of the Three Gorges Dam influence on the Changjiang (Yangtze River) submerged delta

    NASA Astrophysics Data System (ADS)

    Dai, Zhijun; Liu, James T.; Wei, Wen; Chen, Jiyu

    2014-10-01

    While most large river-deltas in the world are facing the risk of subsidence and erosion in the Anthropocene, it is suspected that the Changjiang submerged delta (CSD) could be subjected to the impacts of the world's largest dam, the Three Gorges Dam (TGD). Here we firstly indicate that the CSD went through high accumulation (1958-1978) slight accumulation (1978-1997), slight erosion (1997-2002) and high accumulation (2002-2009), despite the 70% reduction of the sediment load from upstream since the operation of the TGD in 2003. Meanwhile, at the depocenter of the submerged delta, the accumulation maintained a high rate of 10 cm/yr during 1958-2009. This suggests on a longer term, the distal sediment source from the upstream had little effect on the CSD. Within this time frame the changes in the partition of sediment load among the branching channels of the Changjiang Estuary could likely control the shifting of the depocenter of the CSD on a decadal time scale. Episodic extreme floods and storm surges also increased the magnitude of deposition and erosion of the CSD on short-term scales. A re-evaluation of the impacts of TGD on the CSD is urgently needed.

  20. Detection of the Three Gorges Dam influence on the Changjiang (Yangtze River) submerged delta.

    PubMed

    Dai, Zhijun; Liu, James T; Wei, Wen; Chen, Jiyu

    2014-10-16

    While most large river-deltas in the world are facing the risk of subsidence and erosion in the Anthropocene, it is suspected that the Changjiang submerged delta (CSD) could be subjected to the impacts of the world's largest dam, the Three Gorges Dam (TGD). Here we firstly indicate that the CSD went through high accumulation (1958-1978); slight accumulation (1978-1997), slight erosion (1997-2002); and high accumulation (2002-2009), despite the 70% reduction of the sediment load from upstream since the operation of the TGD in 2003. Meanwhile, at the depocenter of the submerged delta, the accumulation maintained a high rate of 10 cm/yr during 1958-2009. This suggests on a longer term, the distal sediment source from the upstream had little effect on the CSD. Within this time frame the changes in the partition of sediment load among the branching channels of the Changjiang Estuary could likely control the shifting of the depocenter of the CSD on a decadal time scale. Episodic extreme floods and storm surges also increased the magnitude of deposition and erosion of the CSD on short-term scales. A re-evaluation of the impacts of TGD on the CSD is urgently needed.

  1. Paleocurrent evidence for lateral displacement of the Pliocene Colorado River delta by the San Andreas fault system, southeastern California

    NASA Astrophysics Data System (ADS)

    Winker, Charles D.; Kidwell, Susan M.

    1986-09-01

    More than 600 paleocurrent measurements from fluvial paleochannels of the early Colorado River delta plain, preserved in the Palm Spring Formation in the Fish Creek Vallecito (FCV) section of southern California, indicate that the FCV section was on the Gulf of California (southeastern) flank of the delta plain as recently as 2.8 Ma. These measurements imply ˜130 km of tectonic translation to the northwest since 2.8 Ma, which can be accounted for by the displacement histories of Baja California and component faults of the San Andreas system. Stratigraphic data from the FCV section and other Neogene localities, when plotted on a palinspastic base, indicate (1) marine transgression of a narrow Gulf of California rift basin and Bouse embayment (site of modern lower Colorado River) by 5.5 Ma, and (2) uplift of the Bouse embayment, initiation of the: lower Colorado River, and southward progradation of the delta to essentially its present position by 4 Ma.

  2. Effects of tectonic deformation and sea level on river path selection: Theory and application to the Ganges-Brahmaputra-Meghna River Delta

    NASA Astrophysics Data System (ADS)

    Reitz, Meredith D.; Pickering, Jennifer L.; Goodbred, Steven L.; Paola, Chris; Steckler, Michael S.; Seeber, Leonardo; Akhter, Syed H.

    2015-04-01

    The set of active rivers of the Ganges-Brahmaputra-Meghna (GBM) Delta in Bangladesh overlies an active plate boundary that continually modifies the landscape of the delta by deformation. The response of rivers to spatially variable subsidence, from tectonic tilting or other causes, has been thought to include preferred occupation of regions of higher subsidence. In this paper, we develop further the theoretical framework for analysis of the interplay of tectonics and river dynamics, and apply this model to conditions in the GBM Delta. First, we examine the overall competition between variable subsidence and channel dynamics, and find that tilting in Bangladesh should be strong enough to influence river path selection. We then present new theory for the effect of subsidence that is spatially (not temporally) variable. We find a constant residence timescale on different parts of the delta, and differing frequencies of avulsion to these locations, and describe the effects of incision or floodplain deposition on these quantities. We present estimates of the channel residence timescale of the Jamuna (Brahmaputra) River reconstructed from the lithology, provenance, and dating of sediment cores. We apply our framework to a map of regional subsidence to predict the effects on avulsion for the Jamuna River. Comparison between our predicted (2150 years) and our stratigraphically based estimates of avulsion timescale (1800 years) shows encouraging consistency.

  3. 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

    USGS Publications Warehouse

    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.

  4. Risks posed by trace organic contaminants in coastal sediments in the Pearl River Delta, China.

    PubMed

    Fung, C N; Zheng, G J; Connell, D W; Zhang, X; Wong, H L; Giesy, J P; Fang, Z; Lam, P K S

    2005-10-01

    Local marine environments in China's Pearl River Delta (PRD), the most rapidly developing region in one of the world's fastest growing economies, have been experiencing significant environmental stress during the past decades. This investigation was conducted to determine the status and trends of persistence organic pollutants (POPs) such as polycyclic aromatic hydrocarbons (PAHs), petroleum hydrocarbons (PHCs), polychlorinated biphenyls (PCBs), organochlorine (OC) pesticides and dioxin-related compounds in marine sediments collected from sixteen coastal stations in the Pearl River Delta (PRD) in March 2003. Elevated concentrations of PAHs (94-4300 ng/g), PCBs (6.0-290 ng/g), PHCs (14-150 microg/g), and DDTs (1.4-600 ng/g) were detected in sediment samples. In addition, 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD)-like activities in the sediment samples were estimated to range from 0.3 to 440 pg TCDD-EQ/g. Sediments collected from Xiashan contained the greatest concentrations of trace organic contaminations amongst all the sampling stations in the present study. The degree of trace organic contamination was, in general, more severe at stations situated along the west shores of the PRD than their counterparts in the east. A preliminary assessment was performed to examine the probable risks to the marine ecosystem due to POPs. The results showed that OC pesticide contamination in the PRD was particularly serious and might pose a threat to the health of the marine inhabitants. PMID:16199239

  5. Natural selection in a bangladeshi population from the cholera-endemic ganges river delta.

    PubMed

    Karlsson, Elinor K; Harris, Jason B; Tabrizi, Shervin; Rahman, Atiqur; Shlyakhter, Ilya; Patterson, Nick; O'Dushlaine, Colm; Schaffner, Stephen F; Gupta, Sameer; Chowdhury, Fahima; Sheikh, Alaullah; Shin, Ok Sarah; Ellis, Crystal; Becker, Christine E; Stuart, Lynda M; Calderwood, Stephen B; Ryan, Edward T; Qadri, Firdausi; Sabeti, Pardis C; Larocque, Regina C

    2013-07-01

    As an ancient disease with high fatality, cholera has likely exerted strong selective pressure on affected human populations. We performed a genome-wide study of natural selection in a population from the Ganges River Delta, the historic geographic epicenter of cholera. We identified 305 candidate selected regions using the composite of multiple signals (CMS) method. The regions were enriched for potassium channel genes involved in cyclic adenosine monophosphate-mediated chloride secretion and for components of the innate immune system involved in nuclear factor κB (NF-κB) signaling. We demonstrate that a number of these strongly selected genes are associated with cholera susceptibility in two separate cohorts. We further identify repeated examples of selection and association in an NF-κB/inflammasome-dependent pathway that is activated in vitro by Vibrio cholerae. Our findings shed light on the genetic basis of cholera resistance in a population from the Ganges River Delta and present a promising approach for identifying genetic factors influencing susceptibility to infectious diseases.

  6. Strain accumulation across the Denali fault in the Delta River canyon, Alaska.

    USGS Publications Warehouse

    Savage, J.C.; Lisowski, M.; Prescott, W.H.

    1981-01-01

    Deformation along the Denali fault in the Delta River canyon was determined from geodetic surveys in 1941/1942, 1970, 1975, and 1979. The data were best for the 1975-79 interval; in that period the average strain accumulation was essentially pure right lateral shear at a rate of 0.6+-0.1 murad/a (a is years) (engineering shear) across a vertical plane striking N87oE. The plane of maximum shear is rotated about 30o countercloskwise from the local strike of the Denali fault but closely coincides with the strike of a major linear segment of the fault that begins 50 km farther W. The deformation between 1941-42 and 1970 is consistent with a similar rate of strain accumulation if one removes the coseismic strain step contributed by the 1964 Alaska earthquake. The 1970-75 deformation is poorly defined owing to uncertainties in the 1970 survey, but the strain accumulation during that period is certainly much less than during the 1975-79 interval. The 1975-79 strain accumulation is interpreted by means of a dislocation model which suggests that the Denali fault in the vicinity of the Delta River Canyon behaves as a leaky transform fault.-Authors

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

    PubMed Central

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

    2015-01-01

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

  8. Inequality and polarization analysis of urban water use in the Yangtze River Delta area, China.

    PubMed

    Zhang, Zhiguo; Shao, Yisheng

    2010-01-01

    Inequality and polarization are terms usually used to describe the overall dispersion of income distribution and the phenomenon of a divided society with a disappearing middle class and increasing rich and poor populations. However, these terms have seldom been used in water sciences. In this paper, the concepts of inequality and polarization are employed to analyze the distribution of urban water use of different cities. Using for reference the conception of Gini coefficient, the EUWU (Equality of Urban Water Use) model is built to analyze the equality of urban water use. And, the PUWU (Polarization of Urban Water Use) model based on exponential functions, which can limit the index of polarization to the range (0, 1) effectively, is built to analyze the polarization of urban water use. Inequality and polarization of resident, industrial and commercial water use in 16 cities in the Yangtze River Delta, the fastest growing region of China, are evaluated using the EUWU model and PUWU model, respectively. The results show that inequality of residential, industrial and commercial water use has decreased by 6.5%, 11.2% and 8.4%, while the index of polarization has increased by 3.9%, 3.8% and 0.1% in Yangtze River Delta area from 2001 to 2006.

  9. Transfer of cadmium from soil to vegetable in the Pearl River Delta area, South China.

    PubMed

    Zhang, Huihua; Chen, Junjian; Zhu, Li; Yang, Guoyi; Li, Dingqiang

    2014-01-01

    The purpose of this study was to investigate the regional Cadmium (Cd) concentration levels in soils and in leaf vegetables across the Pearl River Delta (PRD) area; and reveal the transfer characteristics of Cadmium (Cd) from soils to leaf vegetable species on a regional scale. 170 paired vegetables and corresponding surface soil samples in the study area were collected for calculating the transfer factors of Cadmium (Cd) from soils to vegetables. This investigation revealed that in the study area Cd concentration in soils was lower (mean value 0.158 mg kg(-1)) compared with other countries or regions. The Cd-contaminated areas are mainly located in west areas of the Pearl River Delta. Cd concentrations in all vegetables were lower than the national standard of Safe vegetables (0.2 mg kg(-1)). 88% of vegetable samples met the standard of No-Polluted vegetables (0.05 mg kg(-1)). The Cd concentration in vegetables was mainly influenced by the interactions of total Cd concentration in soils, soil pH and vegetable species. The fit lines of soil-to-plant transfer factors and total Cd concentration in soils for various vegetable species were best described by the exponential equation (y = ax(b)), and these fit lines can be divided into two parts, including the sharply decrease part with a large error range, and the slowly decrease part with a low error range, according to the gradual increasing of total Cd concentrations in soils.

  10. Urban household carbon emission and contributing factors in the Yangtze River Delta, China.

    PubMed

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

    2015-01-01

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

  11. [Spatiotemporal pattern of carbon sources and sinks in Yangtze River Delta region, China].

    PubMed

    Yi, Bai-lu; Han, Ji; Zhou, Xiang; Yang, Fang; Meng, Xing; Cao, Wu-xing; Huang, Lu-xia; Xiang, Wei-ning

    2015-04-01

    Yangtze River Delta region is the world's sixth and China's largest urban agglomeration. Its rapid and massive urbanization has also caused a series of ecological and environmental impacts. This paper accounted the inventory of carbon sources and sinks in Yangtze River Delta region during 1995-2010 and analyzed their spatiotemporal patterns. It was found that the carbon sinks increased by 9.43 million tons from 1995 to 2010, in which forest ecosystem net production in Zhejiang Province was the largest contributor. The "grain for green" policy implemented since 2003 in China played a significant role in increasing the forest area and the carbon sinks. The carbon sources increased by 327 million tons, and energy consumption and industrial processes based emissions accounted for 96% of total carbon sources in 2010. Due to the large share of manufacturing and heavy industries in economy and their dependence on the high carbon intensity energy, either the amount or the growth speed of carbon emissions in Jiangsu Province was the top one in the whole region. Moreover, because the growth speed of net carbon emissions that occurred upon the built-up land was much faster than the sprawl speed of urban built-up land, the net carbon emission intensity kept increasing in the whole region, in which Jiangsu Province demonstrated the fastest increase.

  12. Natural Selection in a Bangladeshi Population from the Cholera-Endemic Ganges River Delta

    PubMed Central

    Karlsson, Elinor K.; Harris, Jason B.; Tabrizi, Shervin; Rahman, Atiqur; Shlyakhter, Ilya; Patterson, Nick; O'Dushlaine, Colm; Schaffner, Stephen F.; Gupta, Sameer; Chowdhury, Fahima; Sheikh, Alaullah; Shin, Ok Sarah; Ellis, Crystal; Becker, Christine E.; Stuart, Lynda M.; Calderwood, Stephen B.; Ryan, Edward T.; Qadri, Firdausi; Sabeti, Pardis C.; LaRocque, Regina C.

    2015-01-01

    As an ancient disease with high fatality, cholera has likely exerted strong selective pressure on affected human populations. We performed a genome-wide study of natural selection in a population from the Ganges River Delta, the historic geographic epicenter of cholera. We identified 305 candidate selected regions using the Composite of Multiple Signals (CMS) method. The regions were enriched for potassium channel genes involved in cyclic AMP-mediated chloride secretion and for components of the innate immune system involved in NF-κB signaling. We demonstrate that a number of these strongly selected genes are associated with cholera susceptibility in two separate cohorts. We further identify repeated examples of selection and association in an NF-kB / inflammasome-dependent pathway that is activated in vitro by Vibrio cholerae. Our findings shed light on the genetic basis of cholera resistance in a population from the Ganges River Delta and present a promising approach for identifying genetic factors influencing susceptibility to infectious diseases. PMID:23825302

  13. [Spatiotemporal pattern of carbon sources and sinks in Yangtze River Delta region, China].

    PubMed

    Yi, Bai-lu; Han, Ji; Zhou, Xiang; Yang, Fang; Meng, Xing; Cao, Wu-xing; Huang, Lu-xia; Xiang, Wei-ning

    2015-04-01

    Yangtze River Delta region is the world's sixth and China's largest urban agglomeration. Its rapid and massive urbanization has also caused a series of ecological and environmental impacts. This paper accounted the inventory of carbon sources and sinks in Yangtze River Delta region during 1995-2010 and analyzed their spatiotemporal patterns. It was found that the carbon sinks increased by 9.43 million tons from 1995 to 2010, in which forest ecosystem net production in Zhejiang Province was the largest contributor. The "grain for green" policy implemented since 2003 in China played a significant role in increasing the forest area and the carbon sinks. The carbon sources increased by 327 million tons, and energy consumption and industrial processes based emissions accounted for 96% of total carbon sources in 2010. Due to the large share of manufacturing and heavy industries in economy and their dependence on the high carbon intensity energy, either the amount or the growth speed of carbon emissions in Jiangsu Province was the top one in the whole region. Moreover, because the growth speed of net carbon emissions that occurred upon the built-up land was much faster than the sprawl speed of urban built-up land, the net carbon emission intensity kept increasing in the whole region, in which Jiangsu Province demonstrated the fastest increase. PMID:26259436

  14. Transfer of Cadmium from Soil to Vegetable in the Pearl River Delta area, South China

    PubMed Central

    Zhang, Huihua; Chen, Junjian; Zhu, Li; Yang, Guoyi; Li, Dingqiang

    2014-01-01

    The purpose of this study was to investigate the regional Cadmium (Cd) concentration levels in soils and in leaf vegetables across the Pearl River Delta (PRD) area; and reveal the transfer characteristics of Cadmium (Cd) from soils to leaf vegetable species on a regional scale. 170 paired vegetables and corresponding surface soil samples in the study area were collected for calculating the transfer factors of Cadmium (Cd) from soils to vegetables. This investigation revealed that in the study area Cd concentration in soils was lower (mean value 0.158 mg kg−1) compared with other countries or regions. The Cd-contaminated areas are mainly located in west areas of the Pearl River Delta. Cd concentrations in all vegetables were lower than the national standard of Safe vegetables (0.2 mg kg−1). 88% of vegetable samples met the standard of No-Polluted vegetables (0.05 mg kg−1). The Cd concentration in vegetables was mainly influenced by the interactions of total Cd concentration in soils, soil pH and vegetable species. The fit lines of soil-to-plant transfer factors and total Cd concentration in soils for various vegetable species were best described by the exponential equation (), and these fit lines can be divided into two parts, including the sharply decrease part with a large error range, and the slowly decrease part with a low error range, according to the gradual increasing of total Cd concentrations in soils. PMID:25247431

  15. Urban household carbon emission and contributing factors in the Yangtze River Delta, China.

    PubMed

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

    2015-01-01

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

  16. Multibeam Mapping of Active Slope Instability Features: Examples from the Fraser River and Squamish River Deltas, British Columbia, Canada

    NASA Astrophysics Data System (ADS)

    Hill, P. R.

    2004-12-01

    Multibeam mapping of the coastal waters of British Columbia has immensly improved our ability to identify and assess submarine landslide and tsunami hazard. This paper will present analysis of high-resolution images of slope instability features from two delta slopes where recent slope failure can be documented through repetitive multibeam mapping and/or comparison with previous single-beam hydrographic soundings. Numerous mass movement features characterize the slope of the Fraser River delta, all the recent features being located at the mouths of distributary channels. Engineering works have maintained the main channel in a fixed position since the 1930's, contributing to over-steepening of the slope and development of a network of submarine channels. Repetitive multibeam mapping shows that recent slope failures have occurred in numerous locations around the main channel lobe, some at the head of a large submarine channel system and others as isolated small failures that form the headwalls of small submarine channels. The scalloped morphology and association with channels, together with volume estimates derived from repetitive multibeam mapping, indicate that these features result from shallow, small volume liquefaction failures. Smaller scale, shallow slides are present on the very shallow water slope area adjacent to the channels, raising the possibility of groundwater seepage as an influence on slope stability. The slide masses from these failures are rapidly transformed into gravity flows that carve the submarine channels. Slides and channels of a similar scale are found at the mouth of a secondary distributary channel and an abandoned distributary channel. The multibeam imagery allows discrimination between recent slide features and relict features, the latter showing infilling or reworking by bottom currents. An area of undulatory seafloor, located on the flank of the main distributary channel lobe, has been cited as a possible creep displacement feature

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

    PubMed

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

    2014-11-01

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

  18. Cryosols of the Northeast Siberian Lena River Delta and its hinterland - genesis and diversity

    NASA Astrophysics Data System (ADS)

    Zubrzycki, Sebastian; Kutzbach, Lars; Pfeiffer, Eva-Maria

    2016-04-01

    The North-Siberian Lena River Delta (LRD) is the largest Arctic delta and an important interface between the Arctic Ocean in the North and the large Siberian land masses in the South. LRD consists not only of Holocene deltaic sediment deposits as a river terrace and the modern active floodplains but also of remnants of the former Pleistocene mainland including large islands of ice-complex sediments and the Arga-Muora-Sise Island, which is composed of pure sand sediments of still debated origin. The highly diverse landscape structure of LRD is reflected by a great variety of permafrost-affected soils (cryosols). This study aims at describing this great cryosol diversity and at analysing the dominant soil-forming processes in this comparatively scarcely studied soil region. The soil development in the investigated continuous permafrost region is limited by the short thawing period of around three months (June to September) and takes place in the shallow (below 1 m) seasonally thawed active layer. The geological parent material plays an important role for the development of soils in the LRD region. The distribution of the various soil types closely follows the pattern of the geomorphic units characterised by differing sedimentation conditions. The properties and genesis of the soils on the Holocene river terrace and the modern floodplains are strongly affected by the enormous amounts of fluvial sediments (about 12 x 106 tons per year) brought by the Lena River into its delta. The fluvial sedimentation together with the also pronounced aeolian sedimentation results in a fast vertical growth of soils. The upward rise of the soil surface leads to an upward movement of the permafrost table resulting in fast incorporation of soil material formed in the supra-permafrost zone into the permafrost. Due to the morphodynamics of ice-wedge polygons and resulting formation of patterned ground with elevated rims and depressed and water-saturated centres, the Holocene river terrace

  19. Hydro-environmental status and soil management of the River Nile Delta, Egypt

    NASA Astrophysics Data System (ADS)

    Elewa, H. H.; El Nahry, A. H.

    2009-04-01

    The sea level rise has its own-bearing on the coastal recession and hydro-environmental degradation of the River Nile Delta. Attempts are made here to use remote sensing to detect the coastal recession in some selected parts and delineating the chemistry of groundwater aquifers and surface water, which lie along south-mid-northern and coastal zone of the Nile Delta. Eight water samples from groundwater monitoring wells and 13 water samples from surface water were collected and analyzed for various hydrochemical parameters. The groundwater samples are classified into five hydrochemical facies on Hill-Piper trilinear diagram based on the dominance of different cations and anions: facies 1: Ca-Mg-Na-HCO3-Cl-SO4 type I; facies 2: Na-Cl-HCO3 type II; facies 3: Na-Ca-Mg-Cl type III, facies 4: Ca-Na-Mg-Cl-HCO3 type IV and facies 5: Na-Mg-Cl type V. The hydrochemical facies showed that the majority of samples were enriched in sodium, bicarbonate and chloride types and, which reflected that the sea water and tidal channel play a major role in controlling the groundwater chemical composition in the Quaternary shallow aquifers, with a severe degradation going north of Nile Delta. Also, the relationship between the dissolved chloride (Cl, mmol/l), as a variable, and other major ion combinations (in mmol/l) were considered as another criterion for chemical classification system. The low and medium chloride groundwater occurs in southern and mid Nile Delta (Classes A and B), whereas the high and very high chloride (classes D and C) almost covers the northern parts of the Nile Delta indicating the severe effect of sea water intrusion. Other facets of hydro-environmental degradation are reflected through monitoring the soil degradation process within the last two decades in the northern part of Nile Delta. Land degradation was assessed by adopting new approach through the integration of GLASOD/FAO approach and Remote Sensing/GIS techniques. The main types of human induced soil

  20. In situ Detection and Habitat Characteristics Analysis of Anammox Bacteria in Sediments from River-network Area, Yangtze River Delta

    NASA Astrophysics Data System (ADS)

    Zhang, Y.; Ruan, X.; Ao, J.; Ma, T.

    2010-12-01

    Anammox (anaerobic ammonium oxidation) is the conversation of NO2-and NH4+ to N2 in anaerobic condition processed by anammox bacteria. Recently, anammox bacteria has been identified in many different freshwater systems around the world. However, Many reports have only focused on the distribution and diversity of anammox bacteria in freshwater systems, little is known about the habitat characteristics of sediments suitable for anammox bacteria. Yangtze River Delta, located in the east of China, has many shallow lakes and river networks. In this study, 41 sediment samples were collected from three typical study areas (shallow lake, regional river and urban rivers) for in situ detection of anammox bacteria and physical-chemical analysis of deposital environment of sediments. Anammox specified sequences were analyzed by PCR amplification of the 16S rRNA from the sediments. Phylogentic analysis revealed that sequences from shallow lakes and regional rivers were related to 'Candidatus Brocadia fulgida', 'Candidatus Brocadia anammoxidans' and 'Candidatus Scalindua', and most of the sequences were affiliated to'Candidatus Brocadia'. No sequence was amplified from urban river's sediments. Principal Components and Classification Analysis (PCCA) of all samples shows that, 13 sites from shallow lake fell in the same set, and 28 samples from the rivers differed from each other. The nitrogen concentration of porewater from the sediments where anammox bacteria were detected in situ are: NH4+-N 6.5~33.71mg/L, NO2--N 0~0.22 mg/L, NO3--N 0.08~3.27mg/L, and the ammonium is the main form of inorganic nitrogen. The total organic carbon (TOC) in porewater varied from 15.07 mg/L to 500.49 mg/L, and the loss on ignition (LOI) in sediments is 3.9%~10.0%. The physical-chemical parameters of deposital environment of urban rivers fell in the former range, but no anammox bacteria was detected from the samples. Further study of the biological characteristics of the bacteria is needed.

  1. Effects of in-channel sand excavation on the hydrology of the Pearl River Delta, China

    NASA Astrophysics Data System (ADS)

    Luo, Xian-Lin; Zeng, Eddy Y.; Ji, Rong-Yao; Wang, Chao-Pin

    2007-09-01

    SummaryThe hydrology and morphology of the Pearl River Delta (PRD; South China) water system has been predominantly dictated by human activities over the last 20 years. Uncontrolled sand excavation occurred in all 324 tributaries, largely to meet the construction needs arising from the rapid economic growth and urbanization in the region. It was estimated that >8.7 × 10 8 m 3 of sand were excavated from 1986 to 2003 based on field surveys of excavating activities and the river hypsography, resulting in average downcutting depths of 0.59-1.73 m, 0.34-4.43 m, and 1.77-6.48 m in the main channels of the West River, North River, and East River (three major water networks in the PRD), respectively. Consequently, the water levels in upstream of the PRD were decreased by 1.59-3.12 m (Sanshui Station). Uneven sand dredging also caused changes in the divided flow ratio (DFR) between various water courses. For example, the DFR increased by 8.8% at the Sanshui Station on the upper part of the North River network from the early 1980s to 1999. DFRs also increased almost 7.7% at the four major runoff outlets in the eastern side of the PRD. As a result, present brackish-water has intruded upward 10-20 km more than in the 1980s. Apparently, there are two sides to the effects of sand excavation. The positive effects are decreased chances of flooding damages, improved navigating conditions, and more water inputs to rapid economically growing regions. The negative effects include increased grade slope and instability of the riverbank, disruption of navigation in upstream dredging pits during dry seasons, and brackish-water intrusion.

  2. Estimating suspended sediment loads in the Pearl River Delta region using sediment rating curves

    NASA Astrophysics Data System (ADS)

    Zhang, Wei; Wei, Xiaoyan; Jinhai, Zheng; Yuliang, Zhu; Zhang, Yanjing

    2012-04-01

    In this study, sediment rating curves are employed to study the variations in relationships between water discharge and suspended sediment concentration based on the recent 50 years of monthly data set in the three major rivers of the Pearl River Delta. Results show that sediment rating parameters vary with time. The lowest rating coefficient, ln(a), and the highest rating exponent, b, mostly occur in the 1980s, indicating that sediment transport reached its peak in this decade at the same level as water discharge. This upward shift of sediment load is probably caused by exacerbated karst rocky desertification in the upper reaches of the Pearl River. However, since the beginning of the 1990s sediment loads from the Pearl River to its estuary began to show a dramatically decreasing trend, which is attributed mainly to deposition in the reservoirs, leading to an increase of ln(a) and a decrease of b. Furthermore, the sediment rating curve in 1957 to1970 is applied to estimate potential sediment load (1971 to 2006) in the absence of human influences. It is also estimated quantitatively by the sediment rating curves that in the 1980s, the annual sediment load decreased by 7.59×106 t/yr because of natural factors, while sediment increase induced by human activities was 20.07×106 t/yr, which resulted in an actual increased sediment load of 12.47×106 t/yr compared with the reference level in 1957 to 1970. In the last two decades, the difference between measured and estimated sediment loads became considerable, and the annual deficit sharply increased to 26.80×106 t/yr in the 1990s, and 50.46×106 t/yr in the 2000s, indicating that human activities, mainly referring to dam and reservoir construction, play a dominant role in the decrease of sediment load. The decrease in sediment supply from the Pearl River should be paid special attention because it may cause serious impacts on the river delta and the coastal ocean.

  3. A methodological approach to rapid assessment of a river flood in coastal waters. First test in the Po River delta

    NASA Astrophysics Data System (ADS)

    Campanelli, Alessandra; Bellafiore, Debora; Bensi, Manuel; Bignami, Francesco; Caccamo, Giuseppe; Celussi, Mauro; Del Negro, Paola; Ferrarin, Christian; Marini, Mauro; Paschini, Elio; Zaggia, Luca

    2014-05-01

    As part of the actions of the flagship project RITMARE (Ricerca ITaliana per il MARE) a daily oceanographic survey was performed on 29th November 2013 in front of the Po River delta (Northern Adriatic Sea). The Po river affects a large part of the Northern Adriatic Sea with strong implications on the circulation and functionality of the basin. Physical-chemical and biological properties of coastal waters were investigated after a moderate flood occurred around 25th-27th November. The cruise activities, carried out using a small research boat, were mainly focused on the test of a methodological approach to investigate the environment variability after a flood event in the framework of rapid assessment. The effects of the flood on the coastal waters, have been evaluated in the field using operational forecasts and real-time satellite imagery to assist field measurements and samplings. Surface satellite chlorophyll maps and surface salinity and current maps obtained from a numerical model forced by meteorological forecast and river data were analyzed to better identify the Po plume dispersion during and after the event in order to better locate offshore monitoring stations at the sea. Profiles of Temperature, Salinity, Turbidity, Fluorescence and Colored Dissolved Organic Matter (CDOM) throughout the water column were collected at 7 stations in front of the Po River delta. Sea surface water samples were also collected for the analysis of nutrients, Dissolved Organic Carbon (DOC) and CDOM (surface and bottom). The CDOM regulates the penetration of UV light throughout the water column and mediates photochemical reactions, playing an important role in many marine biogeochemical processes. Satellite images showed a strong color front that separates the higher-chlorophyll coastal water from the more oligotrophic mid-basin and eastern boundary Adriatic waters. In front of the river mouth, the surface layer was characterized by low salinity (14-15), high turbidity (8-11 NTU

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

    PubMed Central

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

    2014-01-01

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

  5. Methane concentrations and oxidation in nearshore waters of the Lena River Delta

    NASA Astrophysics Data System (ADS)

    Joye, S. B.; Samarkin, V.; Shakhova, N. E.; Semiletov, I. P.

    2014-12-01

    The Arctic is warming dramatically, with potentially catastrophic impacts on climate change through rapid mobilization of labile carbon reservoirs sequestered presently in permafrost. Increasingly, Arctic feedbacks are recognized as key contributors to climate change, including cycles associated with the powerful greenhouse gas methane, whose atmospheric concentration has more than doubled since the pre-industrial epoch. Sustained methane release to the atmosphere from thawing Arctic permafrost and delivery to the coastal ocean through groundwater or riverine discharge or expulsion from the seabed is a positive and likely highly significant feedback to climate warming. Microbially-mediated methane oxidation provides a key sink and effective biofilter that can limit methane fluxes from coastal environments to the atmosphere. We examined methane dynamics on the East Siberian Arctic Shelf by determining concentrations and oxidation rates at a series of stations near the Lena River Delta and moving offshore. Methane concentrations and oxidation rates were highly elevated in and near the river mouth compared to offshore waters, except when the offshore waters were impacted by seabed methane seepage. The regulation of methane oxidation in Arctic waters appears two-fold: first, rates are strongly related to methane availability and second, in the presence of methane, nutrient availability strongly regulates methane consumption. Along the Lena river delta, elevated concentrations of both nutrients and methane create ideal conditions to support high rates of pelagic methanotrophy. Offshore, where nutrient concentrations are lower and more limiting, methane oxidation rates are considerably lower. These data suggest that, at present, nearshore waters are fairly efficient methane sinks while in offshore waters, pelagic methanotrophy is inefficient, allowing methane to escape to the atmosphere.

  6. Evolution and structure of a coastal squirt off the Mississippi River delta: Northern Gulf of Mexico

    NASA Astrophysics Data System (ADS)

    Walker, Nan D.; Huh, Oscar K.; Rouse, Lawrence J.; Murray, Stephen P.

    1996-09-01

    In early October 1992, satellite-derived sea surface temperature data revealed a 200 km long and 10- to 30-km-wide stream of cool water flowing toward the southwest from the Mississippi River delta region. Satellite imagery and in situ measurements have enabled a detailed study of the squirt's kinematics and subsurface characteristics over a 2-week period. In its early stages, the squirt appeared as a narrow, high-speed (>75 cm/s) jet of water which flowed westward over the Mississippi Canyon, forcing a semi-submersible drilling rig to suspend operations from October 2 to 4. After crossing back onto the shelf, the squirt spread laterally, yielding a mushroom-shaped feature, 75 km wide, which consisted of counter-rotating vortices. Northeasterly wind forcing (averaging 10-15 m/s) and water level setup east of the delta appear to have been the primary mechanisms for evolution of the high-velocity currents. Satellite and in situ measurements demonstrate that the dipole eddy was comprised of a cool, low-salinity, low-density water mass at least 26 m deep in the center and 16 m deep along its margins. This event demonstrates that strong northeasterly winds over the northern Gulf of Mexico can initiate along-shelf and off-shelf flows of cooler coastal waters, contributing significantly to seasonal cooling and freshening of the continental shelf and to shelf/slope exchanges of water. During this event, approximately 100 km3 of inner shelf and river water was transported off the continental shelf, a volume equivalent to 17% of the average annual discharge of the Mississippi and Atchafalaya Rivers.

  7. Radon and radium isotope assessment of submarine groundwater discharge in the Yellow River delta, China

    NASA Astrophysics Data System (ADS)

    Peterson, Richard N.; Burnett, William C.; Taniguchi, Makoto; Chen, Jianyao; Santos, Isaac R.; Ishitobi, Tomotoshi

    2008-09-01

    Naturally occurring chemical tracers were used to assess the magnitude of submarine groundwater discharge (SGD) during two different sampling periods at a coastal site south of the Yellow River delta, China. We used salinity and pH as indicators of the terrestrial and recirculated seawater components of discharging groundwater and radium isotopes to quantify offshore transport rates. We then used an hourly time series of multiple radium isotopes (224Ra, 223Ra, and 226Ra) to quantify SGD rates and also used 222Rn and seepage meters to independently quantify SGD rates as a comparison to the radium results. Offshore transport rates were found to range from 3.3 to 4.7 cm s-1. Modeled time series radium activities indicated average SGD rates ranging from 4.5 to 13.9 cm d-1 in September 2006 and from 5.2 to 11.8 cm d-1 in July 2007. Temporal trends associated with the radium approach agree with SGD patterns revealed by automated seepage meters deployed nearby, but the absolute fluxes are about 70% lower than those determined by the seepage meters. Modeled SGD rates based on 222Rn (mean = 13.8 cm d-1 in 2006 and 8.4 cm d-1 in 2007) agree with those determined by the radium analysis. Differences in derived SGD rates between the different radium isotopes (226Ra highest; 224Ra lowest) are likely results of uncertainties in the background activities and our limited selection of appropriate groundwater/pore water end-member values. Scaling our results to the entire Yellow River delta, we find SGD fluxes (and corresponding nitrate fluxes) 2-3 times that of the Yellow River.

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

    PubMed

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

    2014-09-01

    Aquatic organisms' tolerance to water pollution is widely used to monitor and assess freshwater ecosystem health. Tolerance values (TVs) estimated based on statistical analyses of species-environment relationships are more objective than those assigned by expert opinion. Region-specific TVs are the basis for developing accurate bioassessment metrics particularly in developing countries, where both aquatic biota and their responses to human disturbances have been poorly documented. We used principal component analysis to derive a synthetic gradient for four stressor variables (total nitrogen, total phosphorus, dissolved oxygen, and % silt) based on 286 sampling sites in the Taihu Lake and Qiantang River basins (Yangtze River Delta), China. We used the scores of taxa on the first principal component (PC1), which explained 49.8% of the variance, to estimate the tolerance values (TV(r)) of 163 macroinvertebrates taxa that were collected from at least 20 sites, 81 of which were not included in the Hilsenhoff TV lists (TV(h)) of 1987. All estimates were scaled into the range of 1-10 as in TV(h). Of all the taxa with different TVs, 46.3% of TV(r) were lower and 52.4% were higher than TV(h). TV(r) were significantly (p < 0.01, Fig. 2), but weakly (r(2) = 0.34), correlated with TVh. Seven biotic metrics based on TVr were more strongly correlated with the main stressors and were more effective at discriminating references sites from impacted sites than those based on TV(h). Our results highlight the importance of developing region-specific TVs for macroinvertebrate-based bioassessment and to facilitate assessment of streams in China, particularly in the Yangtze River Delta. PMID:24865385

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

    PubMed

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

    2014-09-01

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

  10. Heavy metals in oysters, mussels and clams collected from coastal sites along the Pearl River Delta, South China.

    PubMed

    Fang, Zhan-Qiang; Cheung, R Y H; Wong, M H

    2003-01-01

    Concentrations of 8 heavy metals: cadmium (Cd), copper (Cu), zinc (Zn), lead (Pb), nickel (Ni), chromium (Cr), antimony (Sb) and tin (Sn) were examined in 3 species of bivalves ( Perna viridis, Crassostrea rivularis and Ruditapes philippinarum) collected from 25 sites along the Pearl River Delta coastal waters in the South China Sea from July to August 1996. In general, Cd, Cu, Zn and Sn concentrations in the three bivalve species collected from the Estuarine Zone were significantly higher than those collected from the Western and Eastern Zones of the Pearl River Delta, which are related to the existence of various anthropogenic activities in the catchment of the Pearl River Delta. The Western Estuarine Zone is mainly impacted hy Cr, Ni and Cu contamination. In Victoria Harbor, heavy metal contamination is mainly due to Cu and Pb, Cd, Cu and Zn concentrations in oysters were significantly higher than those in mussels and clams. This could be explained by the fact that oysters live mainly in the Estuarine Zone of the Pearl River Delta which receives most of the polluting discharges from the catchment of the Delta. During turbid condition, heavy metals( soluble or adsorbed on suspended particulates) discharged from the Delta are filtered from the water column and subsequently accumulated into the soft body tissues of oysters. Heavy metal concentrations in the three bivalve species were compared with the maximum permissible levels of heavy metals in seafood regulated by the Public Health and Municipal Services Ordinance, Laws of Hong Kong, and it was revealed that Cd and Cr concentrations in the three bivalve species exceeded the upper limits. At certain hotspots in the Delta, the maximum acceptable daily load for Cd was also exceeded.

  11. Georelational analysis of soil type, soil salt content, landform, and land use in the Yellow River Delta, China.

    PubMed

    Fang, Hongliang; Liu, Gaohuan; Kearney, Michael

    2005-01-01

    The Yellow River Delta, one of China's three major river deltas, is becoming a major region for the development of agriculture and fisheries. Protecting the delicate ecology of newly formed aquatic systems as well as the evolution of soils, natural vegetation, and fauna on older upland environments in the delta is a priority in planning for the wise use of the delta's resources for future agricultural development. In this article, we use a Geographic Information System (GIS) to analyze relationships between land-use/ land-cover characteristics in the Dongying municipality, one of the most intensely developed areas of the delta, and spatial variations in soil salinity and landforms. This analysis reveals that soil salt content decreases from regionally high values in isolated depressions to relatively moderate values in embanked former back swamps, with the lowest values occurring in abandoned river courses. Comparing the present land use on this soil salinity-landform pattern shows that it is basically at odds with general concepts of land suitability for agricultural utilization of saline soils. Crop-based agriculture in the region is probably overdeveloped, whereas more appropriate agricultural development, like cattle and forest production, is underrepresented. Future development should focus on converting farmland in embanked former back swamps and abandoned river courses into grasslands and forests. Crop-based agriculture (up to 151,000 ha) could be planned at the low-salinity terrace uplands and flood plains. The article provides guidelines for decision-makers regarding agricultural land use and wetland protection in the Yellow River Delta.

  12. Characterization of elements in the irrigated water in the Changjiang River Delta Region

    NASA Astrophysics Data System (ADS)

    Yuan, X.

    2009-12-01

    Introduction The river networks are dominated in the Changjiang River Delta Region. Most agricultural areas are irrigated with these small rivers. Rivers also receive the effluence from point and nonpoint sources. It is significative to recognize the distribution and potential hazard of irrigated water in this populated area. Study area and sampling The study area covers about 1.1×106 km2, including 16 cities from the northside of Changjiang River in Jiangsu to the middle Zhejiang. Ninety samples were collected in rural irrigated rivers. And the major cations, anions and trace elements of water were determined. Results We observe that Ca2+ is obviously higher in cations, and Cl-, SO42- higher in anions. The southern Jiangsu and coast of middle Zhejiang show high Na+, the hill area of southern Jiangsu and northern Zhejiang show high Ca2+. HCO3- is relatively uniform distributed in these areas. The high SO42- in a few samples occour in industrial spots of Jiangsu and Zhejiang. Cl- increases in waters along the coast. NO3- fluctuates and disperses in samples. Trace elements in waters are unevenly distributed. The two sides of Changjiang River have high As and Cr. Mercury is higher in southern Jiangsu than in other areas. Iron shows an enrichment in the middle Zhejiang. Compared with the background concentrations of trace elements in the lower Changjiang River, Pb, Cu and Cd are much higher in middle Zhejiang than in other areas. But Zn of most samples are lower than the background value.Cu is associated with organic matter in water. Dicussion The research area consists of hill, plain and coast, where farms, industries and houses distribute. In the hilly area of carbonate-dominated, the waters show high Ca2+ and HCO3-, rivers have high Cl- in vicinity of sea. NO3- and SO42- are strongly influenced by anthopogenic input. NO3- shows a high concentration in areas of fertilizer usage. SO42- increases in areas with a lot of industrial discharge. The distribution of trace

  13. Estuarine science and decision-support tools to restore Puget Sound delta and estuarine ecosystems: The Skagit River Delta

    NASA Astrophysics Data System (ADS)

    Grossman, E. E.; Rosenbauer, R. J.; Takesue, R. K.; Gelfenbaum, G.; Reisenbichler, R.; Paulson, A.; Sexton, N. R.; Labiosa, B.; Beamer, E. M.; Hood, G.; Wyllie-Echeverria, S.

    2006-12-01

    Historic land use, ongoing resource extraction, and population expansion throughout Puget Sound have scientists and managers rapidly seeking effective restoration strategies to recover salmon (a cultural icon, as well as, a host of other endangered species and threatened habitats. Of principal concern is the reduction of salmon (Oncorhynchus spp.) and diminished carrying capacity of critical habitat in deltaic regions. Delta habitats, essential to salmon survival, have lost 70 to 80 % area since ~1850 and are now adjusting to a new suite of environmental changes associated with land use practices, including wetland restoration, and regional climate change. The USGS Coastal Habitats in Puget Sound Project, in collaboration with partners from the Skagit River System Cooperative, University of Washington, and other federal, state, and local agencies, is integrating geologic, biologic, hydrologic, and socioeconomic information to quantify changes in the distribution and function of deltaic-estuarine nearshore habitats and better predict "possible futures". We are combining detailed geologic and geochemical analyses of sedimentary environments, plant biomarkers (n-alkanes, PAHs, fatty-acids, and sterols), and compound-specific isotopes to estimate historic habitat coverage, eelgrass (Zostera marina) abundance and modern characteristics of nutrient cycling. Hydrologic and sediment transport processes are being measured to characterize physical processes shaping modern habitats including sediment transport and freshwater mixing that control the temporal and spatial pattern of substrate and water column conditions available as habitat. We are using geophysical, remote sensing, and modeling techniques to determine large-scale coastal morphologic and land-use change and characterize how alteration of physical, hydrologic, and biogeochemical processes influence the dynamics of freshwater mixing, and sediment and nutrient transport in the nearshore. To assist restoration

  14. The Science and Policy of the First Environmental Flows to the Colorado River Delta

    NASA Astrophysics Data System (ADS)

    Flessa, K. W.; Kendy, E.; Schlatter, K.

    2014-12-01

    The first transboundary flow of water for the environment was delivered to the Colorado River Delta in spring of 2014. This engineered mini-spring flood of 130 million cubic meters (105,000 acre-feet) was implemented as part of Minute 319, an addition to the 1944 U.S.-Mexico Water Treaty. Minute 319 is a temporary agreement, expiring in 2017. Teams of scientists from government agencies, universities, and environmental NGOs from both the U.S. and Mexico are measuring the surface flow rates, inundation, ground water recharge, ground water levels and subsurface flows, geomorphic change, recruitment, survival and health of vegetation, and avian response to the environmental flow. Monitoring includes on-the-ground observations and measurements and remote sensing. Surface water from the pulse flow reached restoration sites, prompted germination of both native and non-native vegetation, recharged groundwater and reached the Gulf of California - the first reconnection of the Colorado River and the sea in 16 years. People in local communities joyously welcomed the return of the river; extensive media coverage was overwhelmingly positive - despite widespread drought in the West. After about ten weeks, most of the pulse flow had infiltrated the subsurface, ponded in a few cut-off meanders, or run to the sea. The river no longer flows. Monitoring of seedling survival, groundwater, vegetation and wildlife will continue through 2017. Results of this landscape-scale experiment will play a role in negotiations to renew the agreement, help model and design future flows and guide the efficient use of water for restoration in semi-arid river systems.

  15. Geomorphological and geotechnical issues affecting the seismic slope stability of the Duwamish River Delta, Port of Seattle, Washington

    USGS Publications Warehouse

    Kayen, Robert E.; Barnhardt, Walter A.; Palmer, Stephen P.

    1999-01-01

    Young Holocene deposits of the Duwamish River valley underlie a highly developed transportation-industrial corridor, extending from the City of Kent to the Elliott Bay-Harbor Island marine terminal facilities. The deposits have been shaped by relative sea-level rise, but also by episodic volcanism and seismicity. A geologic and geotechnical investigation of these river-mouth deposits indicates high initial liquefaction susceptibility during earthquakes, and possibly the potential for unlimited-strain disintegrative flow failure of the delta front.

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

    PubMed

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

    2012-07-01

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

  17. Large-river delta-front estuaries as natural "recorders" of global environmental change.

    PubMed

    Bianchi, Thomas S; Allison, Mead A

    2009-05-19

    Large-river delta-front estuaries (LDE) are important interfaces between continents and the oceans for material fluxes that have a global impact on marine biogeochemistry. In this article, we propose that more emphasis should be placed on LDE in future global climate change research. We will use some of the most anthropogenically altered LDE systems in the world, the Mississippi/Atchafalaya River and the Chinese rivers that enter the Yellow Sea (e.g., Huanghe and Changjiang) as case-studies, to posit that these systems are both "drivers" and "recorders" of natural and anthropogenic environmental change. Specifically, the processes in the LDE can influence ("drive") the flux of particulate and dissolved materials from the continents to the global ocean that can have profound impact on issues such as coastal eutrophication and the development of hypoxic zones. LDE also record in their rapidly accumulating subaerial and subaqueous deltaic sediment deposits environmental changes such as continental-scale trends in climate and land-use in watersheds, frequency and magnitude of cyclonic storms, and sea-level change. The processes that control the transport and transformation of carbon in the active LDE and in the deltaic sediment deposit are also essential to our understanding of carbon sequestration and exchange with the world ocean--an important objective in global change research. U.S. efforts in global change science including the vital role of deltaic systems are emphasized in the North American Carbon Plan (www.carboncyclescience.gov). PMID:19435849

  18. Large-river delta-front estuaries as natural "recorders" of global environmental change.

    PubMed

    Bianchi, Thomas S; Allison, Mead A

    2009-05-19

    Large-river delta-front estuaries (LDE) are important interfaces between continents and the oceans for material fluxes that have a global impact on marine biogeochemistry. In this article, we propose that more emphasis should be placed on LDE in future global climate change research. We will use some of the most anthropogenically altered LDE systems in the world, the Mississippi/Atchafalaya River and the Chinese rivers that enter the Yellow Sea (e.g., Huanghe and Changjiang) as case-studies, to posit that these systems are both "drivers" and "recorders" of natural and anthropogenic environmental change. Specifically, the processes in the LDE can influence ("drive") the flux of particulate and dissolved materials from the continents to the global ocean that can have profound impact on issues such as coastal eutrophication and the development of hypoxic zones. LDE also record in their rapidly accumulating subaerial and subaqueous deltaic sediment deposits environmental changes such as continental-scale trends in climate and land-use in watersheds, frequency and magnitude of cyclonic storms, and sea-level change. The processes that control the transport and transformation of carbon in the active LDE and in the deltaic sediment deposit are also essential to our understanding of carbon sequestration and exchange with the world ocean--an important objective in global change research. U.S. efforts in global change science including the vital role of deltaic systems are emphasized in the North American Carbon Plan (www.carboncyclescience.gov).

  19. Distribution of organophosphorus flame retardants in sediments from the Pearl River Delta in South China.

    PubMed

    Tan, Xiao-Xin; Luo, Xiao-Jun; Zheng, Xiao-Bo; Li, Zong-Rui; Sun, Run-Xia; Mai, Bi-Xian

    2016-02-15

    Twelve organophosphorus flame retardants (PFRs) were identified in the sediments and the sediment core collected from the rivers and the estuary in the Pearl River Delta, with the aim of investigating their spatial and vertical distributions. The concentrations of PFRs ranged from 8.3 to 470 ng/g dry weight with high levels of PFRs in the urban area and the e-waste recycling region. Generally, TPhP, TCPP, TEHP, TCEP, and TBEP were the dominant compounds of the PFRs, the composition of which varied across the different regions, reflecting the different sources of PFRs. In the estuary, the PFRs mainly derived from the Xijiang River and the Shunde sections. Increased concentrations of halogen-containing PFRs have been observed in the upper layers of the sediment core. Conversely, relatively high concentrations of halogen-free PFRs were observed in the lower layers of the sediment core, indicating different usage patterns or environmental behaviors between the halogen and the non-halogen PFRs in the study area. PMID:26657357

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

    PubMed

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

    2014-04-01

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

  1. Recent human impacts on the morphological evolution of the Yangtze River delta foreland: A review and new perspectives

    NASA Astrophysics Data System (ADS)

    Du, Jing-Long; Yang, Shi-Lun; Feng, Huan

    2016-11-01

    This paper reviews the morphological change in the Yangtze River delta due to increasing human impacts from three major aspects. The first is the reduction of sediment supply to the ocean due to dam construction, soil conservation, and sand mining within the Yangtze River basin. The reduced sediment supply has decreased the progradation rate of the delta and triggered erosion in the front of the delta. The second impact relates to the reclamation of intertidal wetlands by human activities. Since the 1950s, approximately 1100 km2 of intertidal land has been embanked, resulting in the disappearance of salt marshes and even the entire intertidal zone along some sections of the coastline. The third change in the delta due to human interference is the construction of deep-waterway structures at the mouth bar, which has greatly modified the local hydrodynamics and morphology. Sediment accretion has increased significantly in these areas as a result of sheltering by these deep-waterway structures. This review shows that human activities have severely altered the natural balance among the hydrodynamics and sediment supply, affecting the morphological features of the Yangtze River watershed and delta. Human impacts on the morphological evolution of deltaic coasts in general are becoming an increasingly concern, and more attention should be paid to the management and mitigation of these effects.

  2. Carbon Sequestration in Mediterranean Tidal Wetlands: San Francisco Bay and the Ebro River Delta (Invited)

    NASA Astrophysics Data System (ADS)

    Callaway, J.; Fennessy, S.; Ibanez, C.

    2013-12-01

    Tidal wetlands accumulate soil carbon at relatively rapid rates, in large part because they build soil to counteract increases in sea-level rise. Because of the rapid rates of carbon sequestration, there is growing interest in evaluating carbon dynamics in tidal wetlands around the world; however, few measurements have been completed for mediterranean-type tidal wetlands, which tend to have relatively high levels of soil salinity, likely affecting both plant productivity and decomposition rates. We measured sediment accretion and carbon sequestration rates at tidal wetlands in two mediterranean regions: the San Francisco Bay Estuary (California, USA) and the Ebro River Delta (Catalonia, Spain). Sampling sites within each region represented a range of conditions in terms of soil salinity and plant communities, and these sites serve as potential analogs for long-term carbon sequestration in restored wetlands, which could receive credits under emerging policies for carbon management. Within San Francisco Bay, we collected six sediment cores per site at four salt marshes and two brackish tidal wetlands (two transects with three stations per transect at each site) in order to identify spatial variation both within and among wetlands in the Estuary. At the Ebro Delta, individual sediment cores were collected across 14 tidal wetland sites, including salt and brackish marshes from impounded areas, river mouths, coastal lagoon, and open bay settings. Cores were collected to 50 cm, and cores were dated using 137Cs and 210Pb. Most sites within San Francisco accreted 0.3-0.5 cm/yr, with slightly higher rates of accretion at low marsh stations; accretions rates based on 137Cs were slightly higher than those based on 210Pb, likely because of the shorter time frame covered by 137Cs dating. Accretion rates from the Ebro Delta sites were similar although more variable, with rates based on 137Cs ranging from 0.1 to 0.9 cm/yr and reflecting the wide range of conditions and management

  3. Employee Training Needs and Perceived Value of Training in the Pearl River Delta of China: A Human Capital Development Approach

    ERIC Educational Resources Information Center

    Au, Alan Kai Ming; Altman, Yochanan; Roussel, Josse

    2008-01-01

    Purpose: This paper aims to explore Hong Kong firms' training needs in the Pearl River Delta, a booming region in the fast growing People Republic of China economy, by resorting to a human capital approach. Also, to identify the training policies selected by those firms in order to cater for those needs. Design/methodology/approach: A survey based…

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

    EPA Science Inventory

    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...

  5. Wave-induced seepage and its possible contribution to the formation of pockmarks in the Huanghe (Yellow) River delta

    NASA Astrophysics Data System (ADS)

    Wang, Hu; Liu, Hongjun; Zhang, Minsheng; Wang, Xiuhai

    2016-01-01

    Wave-induced seepage and its possible contribution to the formation of pockmarks in the Huanghe (Yellow) River delta were investigated experimentally and numerically. Laboratory experiments were carried out to explore the response of a layered silty seabed with various saturation conditions under cyclic wave loads, in which the pore pressure and seepage-related phenomena were particularly monitored. Numerical models to simulate wave-induced seepage in the seabed were presented and evaluated, then applied to the Huanghe River delta. The experimental results show that the excess pore pressure decreases more rapidly at the surface layer, while the seepage-related phenomena are more pronounced when large cyclic loads are applied and the underlying layer is less saturated. The proposed numerical models were verified by comparing with the experiments. The calculated seepage depth agreed well with the depth of the pockmarks in the Huanghe River delta. The experimental and numerical results and the existing insitu investigations indicate that the wave-induced seepage may be a direct cause of the pockmarks in the Huanghe River delta. Extreme storm waves and the dual-layered structure of hard surface layer and weak underlying layer are essential external and internal factors, respectively. Wave- or current-induced scour and transport are possible contributors to the reformation of pockmarks at a later stage.

  6. Biological assessment:Egeria densa control program for the Sacramento/San Joaquin River Delta of California

    Technology Transfer Automated Retrieval System (TEKTRAN)

    A detailed Biological Assessment was developed for the proposed Area wide Egeria densa Control Program to outline the procedures that will be used to control this submerged invasive aquatic plant in the Sacramento/ San Joaquin River Delta, and to help determine if this action is expected to threaten...

  7. Examining the Impact of Nitrous Acid Chemistry on Ozone and PM over the Pearl River Delta Region

    EPA Science Inventory

    The impact of nitrous acid (HONO) chemistry on regional ozone and particulate matter in Pearl River Delta region was investigated using the community multiscale air quality (CMAQ) modeling system and the CB05 mechanism. Model simulations were conducted for a ten-day period in Oct...

  8. Soil Phosphorus Forms and Profile Distributions in the Tidal River Network Region in the Yellow River Delta Estuary

    PubMed Central

    Yu, Junbao; Qu, Fanzhu; Wu, Huifeng; Meng, Ling; Du, Siyao; Xie, Baohua

    2014-01-01

    Modified Hedley fraction method was used to study the forms and profile distribution in the tidal river network region subjected to rapid deposition and hydrologic disturbance in the Yellow River Delta (YRD) estuary, eastern China. The results showed that the total P (Pt) ranged from 612.1 to 657.8 mg kg−1. Dilute HCl extractable inorganic P (Pi) was the predominant form in all profiles, both as absolute values and as a percentage of total extracted Pi. The NaOH extractable organic P (Po) was the predominant form of total extracted Po, while Bicarb-Pi and C.HCl-Po were the lowest fractions of total extracted Pi and Po in all the P forms. The Resin-P concentrations were high in the top soil layer and decreased with depth. The Pearson correlation matrix indicated that Resin-P, Bicarb-Pi, NaOH-Pi, and C.HCl-Pi were strongly positively correlated with salinity, TOC, Ca, Al, and Fe but negatively correlated with pH. The significant correlation of any studied form of organic P (Bicarb-Po, NaOH-Po, and C.HCl-Po) with geochemical properties were not observed in the study. Duncan multiple-range test indicated that the P forms and distribution heterogeneity in the profiles could be attributed to the influences of vegetation cover and hydrologic disturbance. PMID:24971393

  9. Shallow Groundwater Movement in the Skagit River Delta Area, Skagit County, Washington

    USGS Publications Warehouse

    Savoca, Mark E.; Johnson, Kenneth H.; Fasser, Elisabeth T.

    2009-01-01

    Shallow groundwater movement in an area between the lower Skagit River and Puget Sound was characterized by the U.S. Geological Survey to assist Skagit County and the Washington State Department of Ecology with the identification of areas where water withdrawals from existing and new wells could adversely affect streamflow in the Skagit River. The shallow groundwater system consists of alluvial, lahar runout, and recessional outwash deposits composed of sand, gravel, and cobbles, with minor lenses of silt and clay. Upland areas are underlain by glacial till and outwash deposits that show evidence of terrestrial and shallow marine depositional environments. Bedrock exposures are limited to a few upland outcrops in the southwestern part of the study area, and consist of metamorphic, sedimentary, and igneous rocks. Water levels were measured in 47 wells on a quarterly basis (August 2007, November 2007, February 2008, and May 2008). Measurements from 34 wells completed in the shallow groundwater system were used to construct groundwater-level and flow-direction maps and perform a linear-regression analysis to estimate the overall, time averaged shallow groundwater-flow direction and gradient. Groundwater flow in the shallow groundwater system generally moves in a southwestward direction away from the Skagit River and toward the Swinomish Channel and Skagit Bay. Local groundwater flow towards the river was inferred during February 2008 in areas west and southwest of Mount Vernon. Water-level altitudes varied seasonally, however, and generally ranged from less than 3 feet (August 2007) in the west to about 15 feet (May 2008) in the east. The time-averaged, shallow groundwater-flow direction derived from regression analysis, 8.5 deg south of west, was similar to flow directions depicted on the quarterly water-level maps. Seasonal changes in groundwater levels in most wells in the Skagit River Delta follow a typical pattern for shallow wells in western Washington. Water

  10. Extreme saline water advection into the Don River delta and ice advections into Kerch Strait

    NASA Astrophysics Data System (ADS)

    Matishov, G. G.

    2015-11-01

    Analysis of such extreme natural phenomena as inflow of saline transformed waters from the Black Sea into the Don River delta, ice drift, and some others, which have been observed in the Sea of Azov in the recent years, is performed. The process and consequences of the ice movement from the Sea of Azov into Kerch Strait under the effect of hurricane-force NE winds is characterized. Data on the salinity and water level changes during the intensive westerly winds are given. The relationship between salinity and water level during episodes of the surges and downsurges is found. Recommendations for organizing the monitoring measures, intended to increase the accuracy of forecasting emergency situations in the Gulf of Taganrog, Sea of Azov, are presented.

  11. Vegetation, substrate and hydrology in floating marshes in the Mississippi river delta plain wetlands, USA

    USGS Publications Warehouse

    Sasser, C.E.; Gosselink, J.G.; Swenson, E.M.; Swarzenski, C.M.; Leibowitz, N.C.

    1996-01-01

    In the 1940s extensive floating marshes (locally called 'flotant') were reported and mapped in coastal wetlands of the Mississippi River Delta Plain. These floating marshes included large areas of Panicum hemitomon-dominated freshwater marshes, and Spartina patens/Scirpus olneyi brackish marshes. Today these marshes appear to be quite different in extent and type. We describe five floating habitats and one non-floating, quaking habitat based on differences in buoyancy dynamics (timing and degree of floating), substrate characteristics, and dominant vegetation. All floating marshes have low bulk density, organic substrates. Nearly all are fresh marshes. Panicum hemitomon floating marshes presently occur within the general regions that were reported in the 1940's by O'Neil, but are reduced in extent. Some of the former Panicum hemitomon marshes have been replaced by seasonally or variably floating marshes dominated, or co-dominated by Sagittaria lancifolia or Eleocharis baldwinii. ?? 1996 Kluwer Academic Publishers.

  12. Harmful Algae Records in Venice Lagoon and in Po River Delta (Northern Adriatic Sea, Italy)

    PubMed Central

    Bilaničovà, Dagmar; Marcomini, Antonio

    2014-01-01

    A detailed review of harmful algal blooms (HAB) in northern Adriatic Sea lagoons (Po River Delta and Venice lagoon) is presented to provide “updated reference conditions” for future research and monitoring activities. In the study areas, the high mollusc production requires the necessity to identify better methods able to prevent risks for human health and socioeconomical interests. So, an integrated approach for the identification and quantification of algal toxins is presented by combining microscopy techniques with Liquid Chromatography coupled with High Resolution Time of Flight Mass Spectrometry (HPLC-HR-TOF-MS). The method efficiency was first tested on some samples from the mentioned coastal areas, where Dinophysis spp. occurred during summer in the sites directly affected by seawaters. Although cell abundance was always <200 cells/L, the presence of Pectenotoxin-2 (PTX2), detected by HPLC-HR-TOF-MS, indicated the potential release of detectable amounts of toxins even at low cell abundance. PMID:24683360

  13. Spatio-temporal analysis of recent groundwater-level trends in the Red River Delta, Vietnam

    NASA Astrophysics Data System (ADS)

    Bui, Duong Du; Kawamura, Akira; Tong, Thanh Ngoc; Amaguchi, Hideo; Nakagawa, Naoko

    2012-12-01

    A groundwater-monitoring network has been in operation in the Red River Delta, Vietnam, since 1995. Trends in groundwater level (1995-2009) in 57 wells in the Holocene unconfined aquifer and 63 wells in the Pleistocene confined aquifer were determined by applying the non-parametric Mann-Kendall trend test and Sen's slope estimator. At each well, 17 time series (e.g. annual, seasonal, monthly), computed from the original data, were analyzed. Analysis of the annual groundwater-level means revealed that 35 % of the wells in the unconfined aquifer showed downward trends, while about 21 % showed upward trends. On the other hand, confined-aquifer groundwater levels experienced downward trends in almost all locations. Spatial distributions of trends indicated that the strongly declining trends (>0.3 m/year) were mainly found in urban areas around Hanoi where there is intensive abstraction of groundwater. Although the trend results for most of the 17 time series at a given well were quite similar, different trend patterns were detected in several. The findings reflect unsustainable groundwater development and the importance of maintaining groundwater monitoring and a database in the Delta, particularly in urban areas.

  14. Sequence stratigraphy of the subaqueous Changjiang (Yangtze River) delta since the Last Glacial Maximum

    NASA Astrophysics Data System (ADS)

    Xu, Taoyu; Wang, Guoqing; Shi, Xuefa; Wang, Xin; Yao, Zhengquan; Yang, Gang; Fang, Xisheng; Qiao, Shuqing; Liu, Shengfa; Wang, Xuchen; Zhao, Quanhong

    2016-01-01

    This study focuses on sedimentary research at the subaqueous Changjiang (Yangtze River) delta, based on five high-resolution seismic profiles and seven borehole cores with accurate AMS 14C datings. Three distinct seismic units were identified from the seismic profiles according to seismic reflection characteristics, and five sedimentary facies were recognized from borehole cores. These facies constituted a fining upward sedimentary sequence in relation to postglacial sea-level transgression. Three sequence surfaces (sequence boundary (SB), transgressive surface (TS), and maximum flooding surface (MFS)) demarcate the boundaries between early transgressive system tract (E-TST), late transgressive system tract (L-TST), early highstand system tract (E-HST) and late highstand system tract (L-HST), which constitute the sixth order sequence. These system tracts were developed coevally with postglacial sea-level rise. E-TST (~ 19-12 ka BP) corresponds to an incised-valley infilling in the early stages of postglacial transgression whereas L-TST (~ 12-7.5 ka BP) was formed during the last stage of postglacial transgression. The progradational structure of L-TST reflected in seismic profiles is possibly related to the intensification of the East Asian summer monsoon. E-HST (~ 7.5-2 ka BP) was deposited in response to the highstand after maximum postglacial transgression was reached, while L-HST (~ 2 ka BP-present) was initiated by accelerated progradation of the Changjiang delta.

  15. Biology of Amur sleeper (Perccottus glehni) in the Delta of the Selenga River, Buryatia, Russia

    USGS Publications Warehouse

    Litvinov, Alexander G.; O'Gorman, Robert

    1996-01-01

    We determined the fecundity, growth, diet, and density of the Amur sleeper (Perccottus glehni) in the Selenga River Delta on Lake Baikal during 1986-1991 to better understand how this invading exotic will affect Baikal's endemic fishes. We also compared the Amur sleeper's diet with that of other fishes living in the delta. The largest Amur sleepers were about 200 mm long and weighed 200 g; the oldest were age 7. All females were mature at age 2. Fecundity ranged from 884 eggs at age 1 to 37,056 eggs at age 7. Highest densities of Amur sleepers were found in oxbow lakes where densities sometimes exceeded 4,000 fish per ha. The bulk of the diet of Amur sleeper age 2 and older was chironomids, fish, and fish eggs. Chironomids were also important in the diet of the commercially valuable Siberian roach (Rutilus rutilus lacustris) and Siberian dace (Leuciscus leuciscus baicalensis). Thus the Amur sleeper may cause population declines of these important endemic fishes through resource competition and predation on their juvenile life stages. However, Amur sleepers were the species of fish most frequently eaten by Eurasian perch (Perca fluviatilis) and northern pike (Esox lucius). So, maintaining vigorous populations of these two predators may well be an effective strategy for limiting the size of Amur sleeper populations.

  16. Trace Gas Emissions from Extensive Aquaculture Systems in the Red River Delta, Vietnam

    NASA Astrophysics Data System (ADS)

    Beman, J.; Seto, K. C.

    2002-12-01

    The Red River Delta of Vietnam is an area undergoing rapid land use change. Aquaculture development is among the most significant of these transformations, with important economic, social and environmental effects. We explored the potential for managed mangrove' and `converted paddy' aquaculture systems in the Delta to produce and/or consume greenhouse gasses. We measured dissolved concentrations of the radiatively-important trace gasses methane (CH4) and nitrous oxide (N2O), as well as associated parameters. All ponds were super-saturated with CH4, with concentrations ranging from 132-1203 nM, (mean 561 nM) in managed mangrove, and 28-521 nM (mean 110 nM) in converted paddy. Surprisingly, none of the ponds was measurably supersaturated with N2O. Methane fluxes were calculated for all ponds using five well-accepted models of gas flux based on wind speed. Mean flux values ranged from 1.04 to 17.09 mg CH4 m-2 d-1 for managed mangrove, falling somewhere between fluxes reported for natural systems and those receiving sewage inputs. Further measurements should be made in more intensive systems to better understand the potential for trace gas production-particularly N2O-in aquaculture systems.

  17. Concentration of contaminants in breeding bird eggs from the Colorado River Delta, Mexico.

    PubMed

    García-Hernández, Jaqueline; Sapozhnikova, Yelena V; Schlenk, Daniel; Mason, Andrew Z; Hinojosa-Huerta, Osvel; Rivera-Díaz, Juan José; Ramos-Delgado, Norma Alicia; Sánchez-Bon, Gerardo

    2006-06-01

    Organic contaminants (organochlorine [OC], organophosphorus [OP] pesticides and polychlorinated biphenyls [PCBs]), and metals (As, Cd, Hg, Pb, and Se) are a concern to avian health in the Colorado River delta, Mexico. We determined concentrations of contaminants in eggs of three breeding species of birds from the delta (mourning doves [Zenaida macroura], burrowing owls [Athene cunicularia], and marsh wrens [Cistothorus palustris]). We collected 27 eggs of mourning doves, eight eggs of burrowing owls, and 18 eggs of marsh wrens for analyses. Polychlorinated biphenyls, OC, and OP pesticides were analyzed by gas chromatography equipped with an electron capture detector, and metals were analyzed by inductively coupled plasma mass spectrometry. The non-ortho PCB congeners (PCB 77 and 126) were found in mourning dove and burrowing owl eggs at concentrations in which hatchability can be affected. Mean selenium concentration found in marsh wren eggs (5.6 microg/g dry wt) exceeded the level of concern. Arsenic and Cd were found at higher than normal concentrations, Hg concentrations did not exceed the level of concern in any of the species, and Pb concentrations were higher in eggs of species subject to hunting. With the exception of lead, marsh wren eggs contained the highest metal concentrations. PMID:16764484

  18. Concentration of contaminants in breeding bird eggs from the Colorado River Delta, Mexico.

    PubMed

    García-Hernández, Jaqueline; Sapozhnikova, Yelena V; Schlenk, Daniel; Mason, Andrew Z; Hinojosa-Huerta, Osvel; Rivera-Díaz, Juan José; Ramos-Delgado, Norma Alicia; Sánchez-Bon, Gerardo

    2006-06-01

    Organic contaminants (organochlorine [OC], organophosphorus [OP] pesticides and polychlorinated biphenyls [PCBs]), and metals (As, Cd, Hg, Pb, and Se) are a concern to avian health in the Colorado River delta, Mexico. We determined concentrations of contaminants in eggs of three breeding species of birds from the delta (mourning doves [Zenaida macroura], burrowing owls [Athene cunicularia], and marsh wrens [Cistothorus palustris]). We collected 27 eggs of mourning doves, eight eggs of burrowing owls, and 18 eggs of marsh wrens for analyses. Polychlorinated biphenyls, OC, and OP pesticides were analyzed by gas chromatography equipped with an electron capture detector, and metals were analyzed by inductively coupled plasma mass spectrometry. The non-ortho PCB congeners (PCB 77 and 126) were found in mourning dove and burrowing owl eggs at concentrations in which hatchability can be affected. Mean selenium concentration found in marsh wren eggs (5.6 microg/g dry wt) exceeded the level of concern. Arsenic and Cd were found at higher than normal concentrations, Hg concentrations did not exceed the level of concern in any of the species, and Pb concentrations were higher in eggs of species subject to hunting. With the exception of lead, marsh wren eggs contained the highest metal concentrations.

  19. Source apportionment of surface ozone in the Yangtze River Delta, China in the summer of 2013

    NASA Astrophysics Data System (ADS)

    Li, L.; An, J. Y.; Shi, Y. Y.; Zhou, M.; Yan, R. S.; Huang, C.; Wang, H. L.; Lou, S. R.; Wang, Q.; Lu, Q.; Wu, J.

    2016-11-01

    We applied ozone source apportionment technology (OSAT) with tagged tracers coupled within the Comprehensive Air Quality Model with Extensions (CAMx) to study the region and source category contribution to surface ozone in the Yangtze River Delta area in summer of 2013. Results indicate that the daytime ozone concentrations in the YRD region are influenced by emissions both locally, regionally and super-regionally. At urban Shanghai, Hangzhou and Suzhou receptors, the ozone formation is mainly VOC-limited, precursor emissions form Zhejiang province dominate their O3 concentrations. At the junction area among two provinces and Shanghai city, the ozone is usually influenced by all the three areas. The daily max O3 at the Dianshan Lake in July are contributed by Zhejiang (48.5%), Jiangsu (11.7%), Anhui (11.6%) and Shanghai (7.4%), long-range transport constitutes around 20.9%. At Chongming site, the BVOC emissions rate is higher than urban region. Regional contribution results show that Shanghai constitutes 15.6%, Jiangsu contributes 16.2% and Zhejiang accounts for 25.5% of the daily max O3. The analysis of the source category contribution to high ozone in the Yangtze River Delta region indicates that the most significant anthropogenic emission source sectors contributing to O3 pollution include industry, vehicle exhaust, although the effects vary with source sector and selected pollution episodes. Emissions of NOx and VOCs emitted from the fuel combustion of industrial boilers and kilns, together with VOCs emissions from industrial process contribute a lot to the high concentrations in urban Hangzhou, Suzhou and Shanghai. The contribution from regional elevated power plants cannot be neglected, especially to Dianshan Lake. Fugitive emissions of volatile pollution sources also have certain contribution to regional O3. These results indicate that the regional collaboration is of most importance to reduce ambient ozone pollution, particularly during high ozone episodes.

  20. Effects of drought on birds and riparian vegetation in the Colorado River Delta, Mexico

    USGS Publications Warehouse

    Hinojosa-Huerta, Osvel; Nagler, Pamela L.; Carrillo-Guererro, Yamilett K.; Glenn, Edward P.

    2013-01-01

    The riparian corridor in the delta of the Colorado River in Mexico supports internationally important bird habitat. The vegetation is maintained by surface flows from the U.S. and Mexico and by a high, non-saline aquifer into which the dominant phreatophytic shrubs and trees are rooted. We studied the effects of a regional drought on riparian vegetation and avian abundance and diversity from 2002 to 2007, during which time surface flows were markedly reduced compared to the period from 1995 to 2002. Reduced surface flows led to a reduction in native tree cover but an increase in shrub cover, mostly due to an increase in Tamarix spp., an introduced halophytic shrub, and a reduction in Populus fremontii and Salix gooddingii trees. However, overall vegetation cover was unchanged at about 70%. Overall bird density and diversity were also unchanged, but riparian-obligate species tended to decrease in abundance, and generalist species increased. Although reduction in surface flows reduced habitat value and negatively impacted riparian-obligate bird species, portions of the riparian zone exhibited resilience. Surface flows are required to reduce soil salt levels and germinate new cohorts of native trees, but the main source of water supporting this ecosystem is the aquifer, derived from underflows from irrigated fields in the U.S. and Mexico. The long-term prospects for delta riparian habitats are uncertain due to expected reduced flows of river water from climate change, and land use practices that will reduce underflows to the riparian aquifer and increase salinity levels. Active restoration programs would be needed if these habitats are to be preserved for the future.

  1. Dissolved and colloidal trace elements in the Mississippi River delta outflow after Hurricanes Katrina and Rita

    NASA Astrophysics Data System (ADS)

    Shim, Moo-Joon; Swarzenski, Peter W.; Shiller, Alan M.

    2012-07-01

    The Mississippi River delta outflow region is periodically disturbed by tropical weather systems including major hurricanes, which can terminate seasonal bottom water hypoxia and cause the resuspension of shelf bottom sediments which could result in the injection of trace elements into the water column. In the summer of 2005, Hurricanes Katrina and Rita passed over the Louisiana Shelf within a month of each other. Three weeks after Rita, we collected water samples in the Mississippi River delta outflow, examining the distributions of trace elements to study the effect of Hurricanes Katrina and Rita. We observed limited stratification on the shelf and bottom waters that were no longer hypoxic. This resulted, for instance, in bottom water dissolved Mn being lower than is typically observed during hypoxia, but with concentrations still compatible with Mn-O2 trends previously reported. Interestingly, for no element were we able to identify an obvious effect of sediment resuspension on its distribution. In general, elemental distributions were compatible with previous observations in the Mississippi outflow system. Co and Re, which have not been reported for this system previously, showed behavior consistent with other systems: input for Co likely from desorption and conservative mixing for Re. For Cs, an element for which there is little information regarding its estuarine behavior, conservative mixing was also observed. Our filtration method, which allowed us to distinguish the dissolved (<0.02 μm) from colloidal (0.02-0.45 μm) phase, revealed significant colloidal fractions for Fe and Zn, only. For Fe, the colloidal phase was the dominant fraction and was rapidly removed at low salinity. Dissolved Fe, in contrast, persisted out to mid-salinities, being removed in a similar fashion to nitrate. This ability to distinguish the smaller Fe (likely dominantly organically complexed) from larger colloidal suspensates may be useful in better interpreting the bioavailablity

  2. [HALOTOLERANCE OF ENTEROBACTERIA ISOLATED FROM WATER AND FISH IN THE VOLGA RIVER DELTA].

    PubMed

    Obukhova, O V; Lartseva, L V

    2015-01-01

    In the article there are presented the results of a study of halotolerance of enterobacteria isolated from water and fish in the Volga River delta, which were dominant in the microbial landscape of these biotopes. Their halotolerance was studied by means of inoculation of daily pure cultures of meat--peptone broth with 3, 7 and 10% of sodium chloride and incubation at 37°C. At that all studied microflora was found to have significant indices of halotolerance with a predominance of aquatic isolates. At that in 3,0 and 7,0 % NaCl concentrations were very similar, but in 10% NaCl broth the halotolerance of water strain was almost 2.0 times higher than the in fish ones. Among isolated Enterobacteriaceae most halophilic bacteria were from the Proteus group, Citrobacteria and Enterobacteria. The halotolerance of isolated enterobacteria in hydroecosystem of the Volga River delta had seasonal specificity and dynamics. There was established the dynamic growth of this sign in the water and fish strains from spring to autumn. Thus, the analysis of the obtained results of the long-term conducted study has shown the wide dissemination of conditionally pathogenic enterobacteria in water and fish, and their high halotolerance and the ability of some of them to remain viable up to salt production. It gives grounds to recommend the necessity of the introduction of them into the normative documentation in the implementation ofthe sanitary-microbiological control of not only raw materials but also ready salted fish production.

  3. Vegetative Ecological Characteristics of Restored Reed ( Phragmites australis) Wetlands in the Yellow River Delta, China

    NASA Astrophysics Data System (ADS)

    Wang, Xuehong; Yu, Junbao; Zhou, Di; Dong, Hongfang; Li, Yunzhao; Lin, Qianxin; Guan, Bo; Wang, Yongli

    2012-02-01

    In this study, we compared ecological characteristics of wetland vegetation in a series of restoration projects that were carried out in the wetlands of Yellow River Delta. The investigated characteristics include plant composition structure, species diversity and community similarity in three kinds of Phragmites australis wetlands, i.e. restored P. australis wetlands (R1, R2, R3 and R4: restored in 2002, 2005, 2007 and 2009, respectively), natural P. australis wetland (N) and degraded P. australis wetland (D) to assess the process of wetlands restoration. The coverage of the R1 was 99%, which was similar to natural wetland. Among all studied wetlands, the highest and lowest stem density was observed in R1 and R2, respectively, Plant height and stem diameter show the same trend as N > R2 > R1 > R3 > D > R4. Species diversity of restored P. australis wetlands became closed to natural wetland. Both species richness and Shannon-Wiener index had similar tendency: increased first and then decreased with restored time. The highest species richness and species diversity were observed in R2, while the lowest values of those parameters were found in natural P. australis wetland. Similarity indexes between restored wetlands and natural wetland increased with the restoration time, but they were still less than 50%. The results indicate that the vegetation of P. australis wetlands has experienced a great improvement after several years' restoration, and it is feasible to restored degraded P. australis wetlands by pouring fresh water into those wetlands in the Yellow River Delta. However, it is notable that costal degraded P. australis wetland in this region may take years to decades to reach the status of natural wetland.

  4. Dissolved and colloidal trace elements in the Mississippi River Delta outflow after Hurricanes Katrina and Rita

    USGS Publications Warehouse

    Shim, Moo-Joon; Swarzenski, Peter W.; Shiller, Alan M.

    2012-01-01

    The Mississippi River delta outflow region is periodically disturbed by tropical weather systems including major hurricanes, which can terminate seasonal bottom water hypoxia and cause the resuspension of shelf bottom sediments which could result in the injection of trace elements into the water column. In the summer of 2005, Hurricanes Katrina and Rita passed over the Louisiana Shelf within a month of each other. Three weeks after Rita, we collected water samples in the Mississippi River delta outflow, examining the distributions of trace elements to study the effect of Hurricanes Katrina and Rita. We observed limited stratification on the shelf and bottom waters that were no longer hypoxic. This resulted, for instance, in bottom water dissolved Mn being lower than is typically observed during hypoxia, but with concentrations still compatible with Mn–O2 trends previously reported. Interestingly, for no element were we able to identify an obvious effect of sediment resuspension on its distribution. In general, elemental distributions were compatible with previous observations in the Mississippi outflow system. Co and Re, which have not been reported for this system previously, showed behavior consistent with other systems: input for Co likely from desorption and conservative mixing for Re. For Cs, an element for which there is little information regarding its estuarine behavior, conservative mixing was also observed. Our filtration method, which allowed us to distinguish the dissolved (<0.02 μm) from colloidal (0.02–0.45 μm) phase, revealed significant colloidal fractions for Fe and Zn, only. For Fe, the colloidal phase was the dominant fraction and was rapidly removed at low salinity. Dissolved Fe, in contrast, persisted out to mid-salinities, being removed in a similar fashion to nitrate. This ability to distinguish the smaller Fe (likely dominantly organically complexed) from larger colloidal suspensates may be useful in better interpreting the

  5. Presence of pyrethroid pesticides in water and sediments of Ebro River Delta

    NASA Astrophysics Data System (ADS)

    Feo, M. L.; Ginebreda, A.; Eljarrat, E.; Barceló, D.

    2010-11-01

    SummaryThe distribution of pyrethroid insecticides of the Ebro River Delta (NE Spain) was assessed by measuring concentrations in surface water and sediment samples. Pyrethroid extraction from water was carried out by ultrasound-assisted emulsification-extraction (UAEE), while the sediment was sonicated and cleaned up using Florisil cartridge. Method detection of limits (MLODs) for the 12 pyrethroids analyzed by gas chromatography-mass spectrometer in negative chemical ionization (GC-NCI-MS) ranged from 0.03 to 35.8 ng L -1 for water and 2.6 to 62.4 pg g -1 for sediment. Recoveries values were in the range of 47-105% for water and 51-105% for sediments, showing satisfactory robustness of the method for analyzing pyrethroids in water and sediment samples. Cypermethrin was detected in 22 water samples collected from Ebro River Delta, while deltamethrin was present only in three water samples at concentrations ranging from 0.73 ng L -1 to 57.2 ng L -1 and 2 ng L -1 to 58.8 ng L -1 for cypermethrin and deltamethrin, respectively. These concentration levels were higher than median lethal concentration (LC50) values found for deltamethrin and lower than LC50 values found for cypermethrin when short time toxic effects are considered. In sediment samples only cypermethrin was detected at concentration levels ranged from 8.27 ng g -1 to 71.9 ng g -1. These levels were higher than its LC50 values. Environmental dynamic behaviour and fate were also evaluated for cypermethrin measuring the sediment/water partition coefficient (ranging from 5.0 to 6.3) and kinetic data (half-life ranging between 13 and 50 days). Results were in good agreement to those reported in literature

  6. [HALOTOLERANCE OF ENTEROBACTERIA ISOLATED FROM WATER AND FISH IN THE VOLGA RIVER DELTA].

    PubMed

    Obukhova, O V; Lartseva, L V

    2015-01-01

    In the article there are presented the results of a study of halotolerance of enterobacteria isolated from water and fish in the Volga River delta, which were dominant in the microbial landscape of these biotopes. Their halotolerance was studied by means of inoculation of daily pure cultures of meat--peptone broth with 3, 7 and 10% of sodium chloride and incubation at 37°C. At that all studied microflora was found to have significant indices of halotolerance with a predominance of aquatic isolates. At that in 3,0 and 7,0 % NaCl concentrations were very similar, but in 10% NaCl broth the halotolerance of water strain was almost 2.0 times higher than the in fish ones. Among isolated Enterobacteriaceae most halophilic bacteria were from the Proteus group, Citrobacteria and Enterobacteria. The halotolerance of isolated enterobacteria in hydroecosystem of the Volga River delta had seasonal specificity and dynamics. There was established the dynamic growth of this sign in the water and fish strains from spring to autumn. Thus, the analysis of the obtained results of the long-term conducted study has shown the wide dissemination of conditionally pathogenic enterobacteria in water and fish, and their high halotolerance and the ability of some of them to remain viable up to salt production. It gives grounds to recommend the necessity of the introduction of them into the normative documentation in the implementation ofthe sanitary-microbiological control of not only raw materials but also ready salted fish production. PMID:26625611

  7. Vegetative ecological characteristics of restored reed (Phragmites australis) wetlands in the Yellow River Delta, China.

    PubMed

    Wang, Xuehong; Yu, Junbao; Zhou, Di; Dong, Hongfang; Li, Yunzhao; Lin, Qianxin; Guan, Bo; Wang, Yongli

    2012-02-01

    In this study, we compared ecological characteristics of wetland vegetation in a series of restoration projects that were carried out in the wetlands of Yellow River Delta. The investigated characteristics include plant composition structure, species diversity and community similarity in three kinds of Phragmites australis wetlands, i.e. restored P. australis wetlands (R1, R2, R3 and R4: restored in 2002, 2005, 2007 and 2009, respectively), natural P. australis wetland (N) and degraded P. australis wetland (D) to assess the process of wetlands restoration. The coverage of the R1 was 99%, which was similar to natural wetland. Among all studied wetlands, the highest and lowest stem density was observed in R1 and R2, respectively, Plant height and stem diameter show the same trend as N > R2 > R1 > R3 > D > R4. Species diversity of restored P. australis wetlands became closed to natural wetland. Both species richness and Shannon-Wiener index had similar tendency: increased first and then decreased with restored time. The highest species richness and species diversity were observed in R2, while the lowest values of those parameters were found in natural P. australis wetland. Similarity indexes between restored wetlands and natural wetland increased with the restoration time, but they were still less than 50%. The results indicate that the vegetation of P. australis wetlands has experienced a great improvement after several years' restoration, and it is feasible to restored degraded P. australis wetlands by pouring fresh water into those wetlands in the Yellow River Delta. However, it is notable that costal degraded P. australis wetland in this region may take years to decades to reach the status of natural wetland.

  8. Historical trace element distribution in sediments from the Mississippi River delta

    USGS Publications Warehouse

    Swarzenski, P.W.; Baskaran, M.; Rosenbauer, R.J.; Orem, W.H.

    2006-01-01

    Five sediment cores were collected on the shelf of the inner Mississippi Bight in June 2003 for a suite of radionuclides to establish geochronologies and trace elements to examine patterns of contaminant deposition and accumulation. Core sites were chosen to reflect a matrix of variable water depths, proximity to the Mississippi River mouth as the primary source for terrigenous particles, and extent and duration of summertime water column hypoxia. The vertical distribution of 239,240Pu and 210Pbxs (= 210Pbtotal - 226Ra) provided reliable geochronological age constraints to develop models for mass accumulation rates and historic trace element inputs and variations. Mass accumulation rates ranged from 0.27 to 0.87 g cm-2 yr-1 and were internally consistent using either 210Pbxs or 239,240Pu. Measured inventories of 137Cs, 239,240Pu, and 210Pbxs were compared to atmospheric deposition rates to quantify potential sediment focusing or winnowing. Observed variability in calculated mass accumulation rates may be attributed foremost to site-specific proximity to the river mouth (i.e., sediment source), variability in water depth, and enhanced sediment focusing at the Mississippi River canyon site. Trace element concentrations were first normalized to Al, and then Al-normalized enrichment factors (ANEF) were calculated based on preanthropogenic and crustal trace element abundances. These ANEFs were typically > 1 for V and Ba, while for most other elements studied, either no enrichment or depletion was observed. The enrichment of Ba may be related, in part, to the seasonal occurrence of oxygen-depleted subsurface waters off the Mississippi River delta, as well as being an ubiquitous by-product of the petroleum industry. ?? 2006 Estuarine Research Federation.

  9. Polycyclic aromatic hydrocarbons in riverine runoff of the Pearl River Delta (China): concentrations, fluxes, and fate.

    PubMed

    Wang, Ji-Zhong; Guan, Yu-Feng; Ni, Hong-Gang; Luo, Xian-Lin; Zeng, Eddy Y

    2007-08-15

    On the basis of a monthly sampling effort from March 2005 to February 2006, the total concentrations of the sums of 27 and 15 polycyclic aromatic hydrocarbons (defined as sigma27PAHs and sigma15PAHs, respectively) in riverine runoff of the Pearl River Delta (PRD), China, and associated fluxes were determined. No clear temporal and spatial trends of PAH concentrations were found at all eight riverine runoff outlets where the samples were collected. The annual fluxes of sigma27PAHs and sigma15PAHs from the PRD to the coastal ocean were 60.2 and 33.9 metric tons, respectively. Assuming that riverine flux was positively related to the regional emission of PAHs, the annual riverine fluxes from five major rivers in China to the global oceans were estimated, which are quite significant relative to other major rivers of the world. On the basis of mass balance considerations, approximately 87% of sigma15PAHs inputting to the Pearl River Estuary and northern South China Sea was derived from riverine runoff from the PRD. In addition, approcimately 22.3 metric tons of sigma15PAHs annually outflow to open seas, which is equivalent to a concentration of 0.34 pg/L in the global oceans if the PAHs are evenly distributed in the upper 200 m of the water column. A comparison with the global background level of PAHs indicated that approximately 0.4% of PAHs in the open oceans may have been contributed by 1-year discharge from the PRD.

  10. Historical Reconstruction of Organic Carbon Inputs to Sediments in the Colville River Delta, Alaska: The Application of Biomarker Proxies

    NASA Astrophysics Data System (ADS)

    Zhang, X.; Bianchi, T. S.; Allison, M. A.

    2014-12-01

    Arctic permafrost represents about 50% of the total belowground global carbon pool, and thus the fate of this pool, as it thaws in the wake of global warming, warrants close attention. Large-river delta-front estuaries (LDEs) have been shown to be important recorders of natural and human-induced changes in watersheds, as they are critical zones for the exchange of organic carbon between the continents and the ocean. The Colville River is the largest North American Arctic River with a continuous permafrost watershed. Simpson's Lagoon, an eastward distal component of the Colville River Delta is an excellent location for historical reconstruction work since it is an area well protected from intense ice grounding and has minimal bioturbation. Sediment cores were collected from the mouth of the river and the lagoon in August of 2010, and analyzed for bulk organic carbon and nitrogen proxies, biomarkers (including lignin phenols, fatty acids), and compound-specific 13C isotope analysis (CSIA) of fatty acids. Downcore sediment data from CSIA of short-chain fatty acids (C14-C18) to the delta over the past ca. 50 years were found to be more depleted and had a wider isotopic range (-17.0~-33.2‰) than long-chain fatty acids (C22-C30, -30.3~-36.8‰). This possibly reflects alterations of inputs of freshwater flow to the delta which could have resulted in isotopic changes that caused corresponding changes in marine versus freshwater phytoplankton inputs. Downcore short-chain saturated and monounsaturated fatty acid profiles reflected differences in the abundance of bacteria and post-depositional decay of algal inputs across different regions of the delta. Ongoing analyses will also focus on compound-specific radiocarbon analyses (CSRA) of fatty acids and lignin phenols to better understand the changes of organic inputs from terrestrially-derived organic-rich horizons in surface soils vs. old deep permafrost-derived organic horizons.

  11. Distribution, source apportionment, and transport of PAHs in sediments from the Pearl River Delta and the northern South China Sea

    SciTech Connect

    Luo, X.J.; Chen, S.J.; Mai, B.X.; Sheng, G.Y.; Fu, J.M.; Zeng, E.Y.

    2008-07-15

    Polycyclic aromatic hydrocarbons (PAHs) were measured in 59 surface sediments from rivers in the Pearl River Delta and the northern continental shelf of the South China Sea. Total PAH concentrations varied from 138 to 6,793 ng/g dry weight. The sources of PAH inputs to sediments in the Pearl River Delta were qualitatively and quantitatively determined by diagnostic ratios and principal components analysis with multiple linear regression. The results showed that on average coal and wood combustion, petroleum spills, vehicle emissions, and nature sources contributed 36%, 27%, 25%, and 12% of total PAHs, respectively. Coal and biomass combustion was the main source of PAHs in sediments of the South China Sea, whereas petroleum combustion was the main source of pyrolytic PAHs in riverine and estuarine sediments of the Pearl River Delta. Perylene was formed in situ in river sediments and then transported to coastal areas along with other PAHs. The relative abundance of perylene from five-ring PAHs can be used to estimate the contribution of riverine-discharged PAHs to coastal sediments.

  12. Distribution, source apportionment, and transport of PAHs in sediments from the Pearl River Delta and the Northern South China Sea.

    PubMed

    Luo, Xiao-Jun; Chen, She-Jun; Mai, Bi-Xian; Sheng, Guo-Ying; Fu, Jia-Mo; Zeng, Eddy Y

    2008-07-01

    Polycyclic aromatic hydrocarbons (PAHs) were measured in 59 surface sediments from rivers in the Pearl River Delta and the northern continental shelf of the South China Sea. Total PAH concentrations varied from 138 to 6,793 ng/g dry weight. The sources of PAH inputs to sediments in the Pearl River Delta were qualitatively and quantitatively determined by diagnostic ratios and principal components analysis with multiple linear regression. The results showed that on average coal and wood combustion, petroleum spills, vehicle emissions, and nature sources contributed 36%, 27%, 25%, and 12% of total PAHs, respectively. Coal and biomass combustion was the main source of PAHs in sediments of the South China Sea, whereas petroleum combustion was the main source of pyrolytic PAHs in riverine and estuarine sediments of the Pearl River Delta. Perylene was formed in situ in river sediments and then transported to coastal areas along with other PAHs. The relative abundance of perylene from five-ring PAHs can be used to estimate the contribution of riverine-discharged PAHs to coastal sediments.

  13. [Seasonal variation patterns of NH4(+) -N/NO3(-) -N ratio and delta 15 NH4(+) value in rainwater in Yangtze River Delta].

    PubMed

    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.

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

    NASA Astrophysics Data System (ADS)

    Huang, C.; Chen, C. H.; Li, L.; Cheng, Z.; Wang, H. L.; Huang, H. Y.; Streets, D. G.; Wang, Y. J.; Zhang, G. F.; Chen, Y. R.

    2011-05-01

    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, NOx, CO, PM10, PM2.5, 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, NOx, PM10, PM2.5, and VOC emissions. Vehicles take up 12.3 % and 12.4 % of the NOx 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.

  15. Arsenic in groundwater and sediment in the Mekong River delta, Vietnam.

    PubMed

    Hoang, Thi Hanh; Bang, Sunbaek; Kim, Kyoung-Woong; Nguyen, My Hoa; Dang, Duy Minh

    2010-08-01

    A study of groundwater and sediment during 2007-2008 in the Mekong River delta in Vietnam (MDVN) revealed that 26%, 74%, and 50% of groundwater samples were above the US EPA drinking water guidelines for As (10 microg/L), Mn (0.05 mg/L), and Fe (0.3 mg/L). The range of As, Fe, and Mn concentrations in the MDVN were <0.1-1351 microg/L, <0.01-38 mg/L, and <0.01-14 mg/L, respectively. Elevated levels of As were found in groundwater at sampling sites close to the Mekong River and in wells less than 60-70 m deep. An inverse relationship was found between As and Mn concentrations in groundwater. Sediment samples from An Giang and Dong Thap had the highest As concentrations (18 mg/kg and 38 mg/kg, respectively). Arsenic sediment occurred mainly in the poorly crystalline Fe oxide phases. Reductive dissolution of the Fe oxide phase is not necessarily the dominant mechanism of As release to groundwater.

  16. Recent decadal growth of the Atchafalaya River Delta complex: Effects of variable riverine sediment input and vegetation succession

    NASA Astrophysics Data System (ADS)

    Rosen, Timothy; Xu, Y. Jun

    2013-07-01

    The Mississippi River Delta Plain has experienced substantial wetland loss from subsidence, erosion, and sea level rise, threatening coastal communities and the ecosystems that support them. The Atchafalaya River, the largest distributary of the Mississippi River, has one of the few prograding delta features along the ~ 200-km deltaic coastline. Understanding changes in the Atchafalaya River Delta complex (ARDC) development has critical implications for future prediction and management strategy for the Mississippi River Delta Plain. This study was organized to answer two major questions: (1) how did development of the ARDC respond to fluctuation in riverine sediment supply over the period 1989-2010, and (2) has vegetation succession helped stabilize subaerial land? The study quantified annual total suspended sediment yields to the two ARDC subdeltas—Atchafalaya River subdelta (ARSD) and Wax Lake outlet subdelta (WLSD)—classified delta land cover using satellite imagery over ~ 5-year intervals into three classes: barren land, vegetation, and open water and investigated the relationship of delta land change with sediment yield and vegetation succession. Over the entire 21-year study period, we found a net land gain of 59 km2, with the ARSD accounting for 58% of this gain and WLSD 42%. Sediment yield to the subdeltas decreased from an average annual of 38 megatonnes (MT) for ARSD and 18 MT for WLSD during 1989-1995 to an average annual of 24 MT for ARSD and 17 MT for WLSD during 2004-2010, corresponding to the decrease in riverine suspended sediment concentration. Concurrently, total land growth rate decreased from 2.4 km2 y- 1 to 1.6 km2 y- 1 for ARSD and 3.2 km2 y- 1 to 0.6 km2 y- 1 for WLSD. However, the ARDC had a net land loss of 2.1 km2 during 1999-2004 because of tropical system effects in conjunction with the lack of large river floods (defined as discharge > 13,800 m3 s- 1). On average, more than 60% of newly vegetated land remained vegetated in

  17. Remote sensing applications: Environmental assessment of the Colorado River delta in Mexico

    NASA Astrophysics Data System (ADS)

    Nagler, Pamela Lynn

    The extent of revegetation in the Colorado River delta in Mexico is described, with emphasis on the return of native cottonwood (Populus fremontii ) and willow (Salix gooddingii) trees. Low-level aerial and satellite remote sensing methods were combined with ground surveys to census the vegetation in a 100 km reach of riparian corridor in Mexico. Although the invasive plant, saltcedar (Tamarix ramosissima), still dominates the riparian zone, native trees now account for 23% of the vegetation in the delta. Multi-band digital camera images obtained by aircraft were used to calculate the Normalized Difference Vegetation Index (NDVI) and scored for percent vegetation cover (NDVI:%C has r = 0.91***). A Thematic Mapper (TM) image taken concurrently with the aerial survey was similarly classified, and by comparing scenes on the TM and aerials, it was possible to calibrate NDVI with percent vegetation on the TM image. This information was used to conduct a change analysis relating flows in the Colorado River with summer vegetation patterns on TM images for the years 1992--1999. The results support the importance of pulse floods in restoring the ecological integrity of arid-zone rivers. This dissertation also compared transpiration rates of three Sonoran Desert riparian trees using sap flow and leaf temperature methods using constructed canopies (two of each species: Populus fremontii (cottonwood), Salix gooddingii (willow) and Tamarix ramosissima (saltcedar)) in an outdoor experiment in Tucson, Arizona. Canopies were measured over 11 days for both sap flow and canopy and air temperature differential (Tc-Ta) under non stressed and stressed conditions. Objective 1: to determine the strength of the relationship between transpiration (Et) and Tc-Ta to determine if Tc-Ta can be a useful remote sensing method to measure Et for these species. Objective 2: to compare Et rates among species, to determine if the invasive species, saltcedar, has higher Et rates or ecophysiological

  18. Architecture analysis of a river flood-dominated delta during an overall sea-level rise (early Pliocene, SE Spain)

    NASA Astrophysics Data System (ADS)

    García-García, F.; Corbí, H.; Soria, J. M.; Viseras, C.

    2011-05-01

    The sedimentary record of delta-front to prodelta transition that developed during the early Pliocene (Bajo Segura Basin, peri-Mediterranean Betic Cordillera Basin) represents an unusual infilling of an incised valley cutting downwards into late Messinian pelagic marls. The complete delta succession, less than 65 m thick, consists of four upwardly fining and thinning sequences several metres thick. Each sequence consists of basal conglomeratic and coarse-grained sandstone beds (delta-front deposits) evolving upwards to alternating sandstones and silty-marl beds (prodelta deposits). The retrogradational stratal succession pattern is interpreted as having been deposited during an overall sea-level rise. Facies association is characterised by quasi- to planar-laminated sandstones and pebbly sandstones alternating with clast-supported boulders to pebbles, sheet-like climbing cross-laminated sandstones with abundant plant remains, and epsilon cross-stratified and channelized gravels and sandstones. These are interpreted as having been deposited by highly concentrated flows interpreted as hyperpycnal turbidity flows from high (cohesionless debris flows and sinuous submarine channels) to moderate (sheet-like climbing cross-laminated sandstones) discharge river-flood events. Slabs of sediment from unstable banks, outsized clasts which roll onto thin beds from channel mouths, slumps and intraformational breccias in delta front are other signatures (including a lack of bored clasts) which indicate high-energy and rapid deposition at the river mouth, encouraging the delta-front gravitational instability failures. Major changes in the discharge of the river-fed delta could have been caused by brief catastrophic, heavy-precipitation events coupled with quasi-stationary convective orographic rainfall typical of the modern Mediterranean.

  19. Dynamic Emulation Modeling of irrigation water deficit in the Red-Thai Binh River Delta, Vietnam

    NASA Astrophysics Data System (ADS)

    Dinh, Q.; Cassaro, L.; Micotti, M.; Soncini-Sessa, R.

    2013-12-01

    real-world case study: the Red-Thai Binh River Delta in Vietnam. It is a large and complex river system, supplied by five unregulated rivers and four large multi-purpose reservoirs, the operating rules of which have to be designed. In order to ascertain the effects of their regulation on the WD in the Delta, a Mike11 model was calibrated and validated. It describes 320 rivers and canals for a total length of 4200 km, 11 irrigation districts and many structures, among which 88 sluice gates and 302 irrigation water intakes (simulated as controlled pumps). Its inputs are the four reservoirs releases, the non-regulated flows of the five rivers, the sea levels at the nine river mouths, the water demand at each one of the irrigation water intakes. The considered outputs are the daily WD in the 11 districts. The dimension of the state vector of the model is of the order of 16,000. From the high dimensional Mike11, a low dimensional (11 dimension) DEMo model was identified that mimics very well (R2=0.95) the WDs as computed by the Mike11 model. The DEMo model will be later on embedded within a large multi-objective optimal control problem to design the operating rules of the four reservoirs.

  20. Large-river delta-front estuaries as natural “recorders” of global environmental change

    PubMed Central

    Bianchi, Thomas S.; Allison, Mead A.

    2009-01-01

    Large-river delta-front estuaries (LDE) are important interfaces between continents and the oceans for material fluxes that have a global impact on marine biogeochemistry. In this article, we propose that more emphasis should be placed on LDE in future global climate change research. We will use some of the most anthropogenically altered LDE systems in the world, the Mississippi/Atchafalaya River and the Chinese rivers that enter the Yellow Sea (e.g., Huanghe and Changjiang) as case-studies, to posit that these systems are both “drivers” and “recorders” of natural and anthropogenic environmental change. Specifically, the processes in the LDE can influence (“drive”) the flux of particulate and dissolved materials from the continents to the global ocean that can have profound impact on issues such as coastal eutrophication and the development of hypoxic zones. LDE also record in their rapidly accumulating subaerial and subaqueous deltaic sediment deposits environmental changes such as continental-scale trends in climate and land-use in watersheds, frequency and magnitude of cyclonic storms, and sea-level change. The processes that control the transport and transformation of carbon in the active LDE and in the deltaic sediment deposit are also essential to our understanding of carbon sequestration and exchange with the world ocean—an important objective in global change research. U.S. efforts in global change science including the vital role of deltaic systems are emphasized in the North American Carbon Plan (www.carboncyclescience.gov). PMID:19435849

  1. Sandy River Delta Habitat Restoration : Annual Report, January 2008 - March 2009.

    SciTech Connect

    Dobson, Robin

    2009-09-11

    During the period 2008-2009, there were 2 contracts with BPA. One (38539) was dealing with the restoration work for 2007 and the other (26198) was an extension on the 2006 contract including the NEPA for Dam removal on the old channel of the Sandy River. For contract 38539, the Sandy River Delta Habitat Restoration project continued its focus on riparian hardwood reforestation with less emphasis on wetlands restoration. Emphasis was placed on Sundial Island again due to the potential removal of the dike and the loss of access in the near future. AshCreek Forest Management was able to leverage additional funding from grants to help finance the restoration effort; this required a mid year revision of work funded by BPA. The revised work not only continued the maintenance of restored hardwood forests, but was aimed to commence the restoration of the Columbia River Banks, an area all along the Columbia River. This would be the final restoration for Sundial Island. The grant funding would help achieve this. Thus by 2011, all major work will have been completed on Sundial Island and the need for access with vehicles would no longer be required. The restored forests continued to show excellent growth and development towards true riparian gallery forests. Final inter-planting was commenced, and will continue through 2010 before the area is considered fully restored. No new wetland work was completed. The wetlands were filled by pumping in early summer to augment the water levels but due to better rainfall, no new fuel was required to augment existing. Monitoring results continued to show very good growth of the trees and the restoration at large was performing beyond expectations. Weed problems continue to be the most difficult issue. The $100,000 from BPA planned for forest restoration in 2008, was augmented by $25,000 from USFS, $120,000 from OR150 grant, $18,000 from LCREP, and the COE continued to add $250,000 for their portion. Summary of the use of these funds are

  2. High-resolution (spatial and temporal) Hydrodynamic Modeling in the Lower Mississippi River Delta

    NASA Astrophysics Data System (ADS)

    Karadogan, E.; Danchuk, S.; Berger, C.; Brown, G.; Willson, C.

    2007-12-01

    The lower Mississippi River is a highly engineered system existing in one of the world's largest deltas. This system is subject to a variety of spatial and temporal forcings due to its large watershed (drains about 41% of the continental U.S.) and from the Gulf of Mexico. Future perturbations on this system are anticipated due to the impacts of global climate change (e.g., rising eustatic sea level, changes in weather patterns) and from proposed modifications to the system such as diversion structures aimed at providing freshwater nutrients and sediments to the rapidly degrading coastal wetlands. Numerical modeling will play a large role in improving our understanding and management of the system and the ability to properly design future structural features. These models will need to have the necessary spatial and temporal resolution to account for the many important processes in the river, the Gulf of Mexico, and in the wetland areas where small distributary channels will form and wetting/drying must be accounted for. This paper will investigate the ability of a 2D shallow water and sediment model to reproduce the complex distributary development associated with flow diversions into quiescent bays. A reach of the Lower Mississippi River from Point a la Hache to the Gulf of Mexico was used as a test domain to evaluate the performance and capabilities of the U.S. Army Corps of Engineers ADaptive Hydraulics (ADH) model. ADH is an unstructured finite element modeling system that includes unsaturated Richards' equations for groundwater, Navier Stokes for nonhydrostatic flow calculations, and Shallow Water equations. ADH conducts automated refinement and coarsening of the mesh based upon flow characteristics. In this case the 2D shallow water model is being used. It includes coupled flow and sedimentation. An unstructured mesh was developed for the study area which includes detailed bathymetry and topography from available survey data. The mesh is fine enough to capture

  3. High Frequency Time-series of the Dynamic Sedimentation Processes on the Western Shelf of the Mississippi River Delta

    NASA Astrophysics Data System (ADS)

    Dail, M. B.; Corbett, D. R.; McKee, B.; Duncan, D.

    2004-12-01

    Rivers annually transport billions of tons of organic and inorganic sediment to coastal environments, making them an extremely important part of global biogeochemical cycles. However, the majority of the freshwater and suspended materials are delivered to the coastal ocean by only a few rivers. In these river-dominated ocean margins (RiOMar), sediments are deposited and re-suspended repeatedly before stable deposition. This sediment cycling is poorly understood and is critical to understanding how deltas and continental shelves, considered to be major repositories of organic carbon in marine sediments, manipulate the global carbon cycle and biogeochemical processes affecting coastal environments. During six cruises in the fall of 2003 (October, November, and December) and spring of 2004 (March, April, and May), on the shelf west of the Mississippi River Delta, sediment samples collected from cores were analyzed for particle reactive radionuclides (210Pb, 137Cs, and 234Th) to create a quantitative high frequency time-series of sediment deposition and erosion processes and evaluate the transport and fate of material on the shelf. Based on previous work completed by Corbett et al. (2004), seasonal variations in short-lived tracers could be explained by river flow and weather conditions. Inventories of the tracers collected during the fall cruises suggest increased deposition during the late summer months and that most sediment reworking and export occurs during the winter months, typically a period of low/increasing river discharge and increased weather forcing.

  4. Sustainability of massively anthropic deltas via dispersal of sediment to manage land building: results from two unique case studies, the Mississippi River (U.S.A.) and the Yellow River (China) deltas

    NASA Astrophysics Data System (ADS)

    Nittrouer, Jeffrey

    2016-04-01

    studies of both the Mississippi and Yellow rivers have been used to inform and validate numerical modeling efforts that seek to replicate the morphodynamics of the two diversions. The aim is to evaluate best practices for building deltaic landscape. Based on these research efforts, there are key similarities found for the delta systems: 1) coarse (sandy) sediment is the primary contributor to subaerial delta development, despite the abundance of mud for both rivers; 2) the influx of freshwater into estuarine regions of deltas has tremendous impact on vegetation development, and therefore the cohesion of the deltaic sediment deposit; and 3) it is feasible to produce efficient diversions that maximize sediment delivery and still provide for continued use of the riverine resource (for example, navigation of the channel by vessels). These findings are critical when considering future plans that seek sustainable management practices of other large, anthropic fluvial deltaic systems.

  5. Groundwater response to the 2014 pulse flow in the Colorado River Delta

    USGS Publications Warehouse

    Kennedy, Jeffrey; Rodriguez-Burgueno, Eliana; Ramirez-Hernandez, Jorge

    2016-01-01

    During the March-May 2014 Colorado River Delta pulse flow, approximately 102 × 106 m3 (82,000 acre-feet) of water was released into the channel at Morelos Dam, with additional releases further downstream. The majority of pulse flow water infiltrated and recharged the regional aquifer. Using groundwater-level and microgravity data we mapped the spatial and temporal distribution of changes in aquifer storage associated with pulse flow. Surface-water losses to infiltration were greatest around the Southerly International Boundary, where a lowered groundwater level owing to nearby pumping created increased storage potential as compared to other areas with shallower groundwater. Groundwater levels were elevated for several months after the pulse flow but had largely returned to pre-pulse levels by fall 2014. Elevated groundwater levels in the limitrophe (border) reach extended about 2 km to the east around the midway point between the Northerly and Southerly International Boundaries, and about 4 km to the east at the southern end. In the southern part of the delta, although total streamflow in the channel was less due to upstream infiltration, augmented deliveries through irrigation canals and possible irrigation return flows created sustained increases in groundwater levels during summer 2014. Results show that elevated groundwater levels and increases in groundwater storage were relatively short lived (confined to calendar year 2014), and that depressed water levels associated with groundwater pumping around San Luis, Arizona and San Luis Rio Colorado, Sonora cause large, unavoidable infiltration losses of in-channel water to groundwater in the vicinity.

  6. Coastal Vulnerability and Load Induced Subsidence of the Modern Mississippi River Delta and Environs

    NASA Astrophysics Data System (ADS)

    Dokka, R. K.; Ivins, E. R.; Blom, R. G.

    2006-12-01

    The disasters wrought by Hurricanes Katrina and Rita along the northern Gulf coast have heightened our awareness of the vulnerability of this low-lying landscape to storm surge. Although topographically subdued, the surface is the product of the dynamic interplay between the processes of subsidence, sediment accretion, and eustasy. Quantification and determination of causative processes of subsidence are thus essential as Society rebuilds and protects communities and contemplates restoration of the coastal ecosystem. Previous models for subsidence have emphasized the roles of shallow compaction and anthropomorphic effects. We agree that these processes are important, but also note that the isostatic impact of both the load of the delta sediments and the effects of water loading following glacial intervals have never been integrated into landscape models. It is thus not surprising that previous models cannot explain the recent geodetic measurements that show that subsidence is geographically more extensive and has been occurring at rates faster than previously anticipated. Here, we explore the combined 3-D physical implications of both sediment loading (delta) and water loading (eustasy) in south Louisiana and Mississippi over the course of the last several glacial cycles. Our models are based on a viscoelastic Earth and successfully explain the gross magnitude of modern subsidence measured by GPS, leveling, InSAR, and mareographs throughout the region. In areas of significant anomalies (spikes in observed subsidence rates that cannot be explained by load models), most can be explained as consequences of local processes such as faulting, fluid withdrawal (generally water), and drainage projects. The models suggest the possibility that additional loads (alluvial valley of the Mississippi River and offshore deposits) also play a role in subsidence.

  7. Distribution and condition of larval and juvenile Lost River and shortnose suckers in the Williamson River Delta restoration project and Upper Klamath Lake, Oregon

    USGS Publications Warehouse

    Burdick, Summer M.; Brown, Daniel T.

    2010-01-01

    Federally endangered Lost River sucker (Deltistes luxatus) and shortnose sucker (Chasmistes brevirostris) were once abundant throughout their range but populations have declined. They were extirpated from several lakes in the 1920s and may no longer reproduce in others. Poor recruitment to the adult spawning populations is one of several reasons cited for the decline and lack of recovery of these species and may be the consequence of high mortality during juvenile life stages. High larval and juvenile sucker mortality may be exacerbated by an insufficient quantity of suitable or high quality rearing habitat. In addition, larval suckers may be swept downstream from suitable rearing areas in Upper Klamath Lake into Keno Reservoir, which is seasonally anoxic. The Nature Conservancy flooded about 3,600 acres (1,456 hectares) to the north of the Williamson River mouth (Tulana Unit) in October 2007 and about 1,400 acres (567 hectares) to the south and east of the Williamson River mouth (Goose Bay Unit) a year later to retain larval suckers in Upper Klamath Lake, create nursery habitat, and improve water quality. The U.S. Geological Survey joined a long-term research and monitoring program in collaboration with The Nature Conservancy, the Bureau of Reclamation, and Oregon State University in 2008 to assess the effects of the Williamson River Delta restoration on the early life-history stages of Lost River and shortnose suckers. The primary objectives of the research were to describe habitat colonization and use by larval and juvenile suckers and non-sucker fishes and to evaluate the effects of the restored habitat on the health and condition of juvenile suckers. This report summarizes data collected in 2009 by the U.S. Geological Survey as a part of this monitoring effort. The Williamson River Delta appeared to provide suitable rearing habitat for endangered larval Lost River and shortnose suckers in 2008 and 2009. Larval suckers captured in this delta typically were

  8. Influences of Relative Sea-Level Rise and Mississippi River Delta Plain Evolution on the Holocene Middle Amite River, Southeastern Louisiana

    USGS Publications Warehouse

    Autin, W.J.

    1993-01-01

    The Holocene geomorphic history of southeastern Louisiana's middle Amite River is recorded in the stratigraphy of three alloformations, identified in decreasing age as the Watson (WAT), Denham Springs (DS), and Magnolia Bridge (MAG). The WAT meander belt formed by at least 9000 yr B.P., when sea level was lower and the Amite River was tributary to a larger ancestral drainage basin. The DS became an active meander belt by at least 3000 yr B.P., in response to relative sea-level rise and eastward progradation of the Mississippi River delta plain. The MAG developed its meander belt, in part, during the European settlement of the drainage basin, and is now attempting to adjust to modern anthropogenic influences. Geomorphic influences on the middle Amite River floodplain have temporal and spatial components that induce regional- and local-scale effects. Regional extrinsic influences caused meander belt avulsion that produced alloformations. However, local influences produced intrinsic geomorphic thresholds that modified channel morphology within a meander belt but did not induce alloformation development. Base-level influences of the relative sea-level rise and the Mississippi River delta plain were so dominant that the effects of possible climate change were not recognized in the Holocene Amite River system.

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

    PubMed

    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

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

    PubMed

    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

  11. Absorption coefficient of urban aerosol in Nanjing, west Yangtze River Delta, China

    NASA Astrophysics Data System (ADS)

    Zhuang, B. L.; Wang, T. J.; Liu, J.; Ma, Y.; Yin, C. Q.; Li, S.; Xie, M.; Han, Y.; Zhu, J. L.; Yang, X. Q.; Fu, C. B.

    2015-12-01

    Absorbing aerosols can significantly modulate short-wave solar radiation in the atmosphere, affecting regional and global climate. The aerosol absorption coefficient (AAC) is an indicator that assesses the impact of absorbing aerosols on radiative forcing. In this study, the near-surface AAC and absorption Ångström exponent (AAE) in the urban area of Nanjing, China, are characterized on the basis of measurements in 2012 and 2013 using the seven-channel Aethalometer (model AE-31, Magee Scientific, USA). The AAC is estimated with direct and indirect corrections, which result in consistent temporal variations and magnitudes of AAC at 532 nm. The mean AAC at 532 nm is about 43.23 ± 28.13 M m-1 in the urban area of Nanjing, which is much lower than that in Pearl River Delta and the same as in rural areas (Lin'an) in Yangtze River Delta. The AAC in the urban area of Nanjing shows strong seasonality (diurnal variations); it is high in cold seasons (at rush hour) and low in summer (in the afternoon). It also shows synoptic and quasi-2-week cycles in response to weather systems. Its frequency distribution follows a typical log-normal pattern. The 532 nm AAC ranging from 15 to 65 M m-1 dominates, accounting for more than 72 % of the total data samples in the entire study period. Frequent high pollution episodes, such as those observed in June 2012 and in winter 2013, greatly enhanced AAC and altered its temporal variations and frequency distributions. These episodes are mostly due to local emissions and regional pollution. Air masses flowing from northern China to Nanjing can sometimes be highly polluted and lead to high AAC at the site. AAE at 660/470 nm from the Schmid correction (Schmid et al., 2006) is about 1.56, which might be more reasonable than from the Weingartner correction (Weingartner et al., 2003). Low AAEs mainly occur in summer, likely due to high relative humidity (RH) in the season. AAC increases with increasing AAE at a fixed aerosol loading. The RH

  12. Intercomparison study of atmospheric methane and carbon dioxide concentrations measured at the Ebre River Delta Station

    NASA Astrophysics Data System (ADS)

    Occhipinti, Paola; Morguí, Josep Anton; Àgueda, Alba; Batet, Oscar; Borràs, Sílvia; Cañas, Lídia; Curcoll, Roger; Grossi, Claudia; Nofuentes, Manel; Vazquez, Eusebi; Rodó, Xavier

    2015-04-01

    In the framework of the ClimaDat project, IC3 has established a network of eight monitoring stations across the Iberian Peninsula and the Canarian Archipelago with the aim of studying climate processes. The monitoring station at the Ebre River Delta (DEC3) is located in the Ebre River Delta Natural Park (40° 44' N; 0° 47' E) and it is characterized by the typical North-Western Mediterranean climate. Since 2013, atmospheric greenhouse gases (GHG) and 222Rn tracer gas together with the meteorological parameters are continuously measured from a 10 m a.g.l. height tower. Atmospheric GHG (CO2, CH4, CO and N2O) concentrations are determined using a Picarro analyzer G2301 (CO2 and CH4) and a modified gas chromatograph (GC) Agilent 6890N (CO2, CH4, CO and N2O). Open data access is available from the www.climadat.es website. Data collected at the DEC3 station are also submitted to the InGOS platform since this station is part of the InGOS European infrastructure project. Researchers from the Laboratory of the Atmosphere and the Oceans (LAO) at IC3 have performed an intercomparison study at the DEC3 site between three different Picarro analyzers (two Picarro G2301 and one Picarro G2301M), a Los Gatos Research (LGR) analyzer and the GC system already installed at the station. The aim of this study is to compare and assess the measuring agreement between the four optical gas analyzers and the GC. In the first part of the experiment, all instruments have been calibrated using NOAA gases as primary standards analyzing five Praxair provided targets to evaluate the precision of the measuring instruments. Max Plank Institute (MPI) gases have been used as secondary standards for the GC whereas Praxair provided tanks are used as secondary standards for the Picarro and the LGR analyzers. In the second part of the experiment, atmospheric GHG were measured from natural atmospheric air taken from a 10 m a.g.l. inlet. Daily cycles of GHG measurements were carried out using different

  13. Distribution and abundance of the Yuma clapper rail (Rallus longirostris yumanensis) in the Colorado River delta, México

    USGS Publications Warehouse

    Hinojosa-Huerta, Osvel; DeStefano, Stephen; Shaw, William W.

    2001-01-01

    We estimated the abundance of Yuma clapper rails in the Ciénega de Santa Clara and determined the distribution of the subspecies in the Colorado River delta region in México. The maximum estimate of abundance was 6629 individuals (95% C.I. 4859–8399), assuming a response rate by rails to taped calls of 60%. Rails were widely distributed in the delta, occupying almost all marshlands dominated by cattail. As this is an endangered subspecies shared by México and the U.S., the conservation of the delta ecosystem should be the interest of both countries, especially when water management decisions upstream in the U.S. have an impact over natural areas downstream in México.

  14. Spatiotemporal Dynamics of River Channel Migration on the Ganges-Brahmaputra Delta: 2000-2013

    NASA Astrophysics Data System (ADS)

    Small, C.; Chiu, S.; Sousa, D.; Mondal, D. R.; Steckler, M. S.; Akhter, S. H.; Mia, B.; Goodbred, S. L., Jr.; Wilson, C.; Seeber, L.

    2014-12-01

    We use multitemporal multiscale satellite remote sensing to complement field observations and subsurface measurements to better understand the relationship between recent and historic fluvial dynamics on the Ganges-Brahmaputra (GB) delta. To provide regional context for the interannual changes in river channel geometry we conduct spatiotemporal (ST) analyses of MODIS Enhanced Vegetation Index (EVI) imagery for 2000-2013 using a new method of Empirical Orthogonal Function (EOF) analysis. We use EVI because it distinguishes water from wet and dry sediment on the basis of the spectral slope at VNIR wavelengths. Water has a negative slope while dry sediment has a small positive slope and vegetation has a large positive slope. To characterize the ST patterns associated with river channel migration we use iterative EOF analysis (iEOF). In iEOF we first conduct a single year EOF analysis for each year in the time series to identify the primary spatial principal component (PC1) for each year and separate this from the spatial structure of the subannual temporal patterns associated with vegetation phenology. We then construct a decadal time series of PC 1 for each single year and conduct a second EOF analysis of the time series of 13 individual year PCs. The standard EOFs of the full (312 images x 16 day) time series only resolve a decadal trend (EOF 8), but the iEOF clearly distinguishs the progressive decadal trend (EOF 2) from the cyclic component (EOF 3) of decadal changes in sediment reflectance. The temporal feature space constructed from PC 2 and PC 3 (corresponding to temporal EOFs 2 and 3) distinguishes pixels with progressive decadal increases and decreases in reflectance from pixels with cyclic changes. Evolution of the annual structure is animated at www.youtube.com/watch?v=UM1UYvdnYXk Despite significant differences in the 2 rivers'morphologies, and the considerable magnitude of flooding every year, we observe year-to-year continuity in the progressive

  15. Distribution and condition of larval and juvenile Lost River and shortnose suckers in the Williamson River Delta restoration project and Upper Klamath Lake, Oregon

    USGS Publications Warehouse

    Burdick, Summer M.

    2012-01-01

    Federally endangered Lost River sucker (Deltistes luxatus) and shortnose sucker (Chasmistes brevirostris) were once abundant throughout their range but populations have declined. They were extirpated from several lakes in the 1920s and may no longer reproduce in other lakes. Poor recruitment to the adult spawning populations is one of several reasons cited for the decline and lack of recovery of these species and may be the consequence of high mortality during juvenile life stages. High larval and juvenile sucker mortality may be exacerbated by an insufficient quantity of suitable or high-quality rearing habitat. In addition, larval suckers may be swept downstream from suitable rearing areas in Upper Klamath Lake into Keno Reservoir, where they are assumed lost to Upper Klamath Lake populations. The Nature Conservancy flooded about 3,600 acres (1,456 hectares) to the north of the Williamson River mouth (Tulana) in October 2007, and about 1,400 acres (567 hectares) to the south and east of the Williamson River mouth (Goose Bay Farms) in October 2008, in order to retain larval suckers in Upper Klamath Lake, create nursery habitat, and improve water quality. The U.S. Geological Survey joined a long-term research and monitoring program in collaboration with The Nature Conservancy, the Bureau of Reclamation, and Oregon State University in 2008 to assess the effects of the Williamson River Delta restoration on the early life-history stages of Lost River and shortnose suckers. The primary objectives of the research were to describe habitat colonization and use by larval and juvenile suckers and non-sucker fishes and to evaluate the effects of the restored habitat on the health and condition of juvenile suckers. This report summarizes data collected in 2010 by the U.S. Geological Survey as a part of this monitoring effort and follows two annual reports on data collected in 2008 and 2009. Restoration modifications made to the Williamson River Delta appeared to provide

  16. 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.

    PubMed

    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.

  17. Spatial and Seasonal Variations of Total Petroleum Hydrocarbon in Surface Water and Sediment in Pearl River Delta.

    PubMed

    Zhao, Jiandi; Yin, Pinghe; Zhao, Ling; Yu, Qiming; Lu, Gang

    2015-09-01

    A field study in the Pearl River Delta of China was conducted in order to describe to the spatial and seasonal variation of occurrence and concentrations of total petroleum hydrocarbon (TPH) in surface water and sediments. Petroleum hydrocarbons and isoprenoid alkanes were quantified by UV spectroscopy and gas chromatography with a mass selective detector. The concentrations of TPH ranged from 4.3 to 68.7 µg L(-1) in surface water, and from 66.6 to 1445 µg g(-1) in surface sediments. The ratios of pristine to phytane suggested that the main sources of TPH in the sediment were petroleum importation. The highest concentrations of TPH were present in the spring season. When compared with results from previous studies, it can be concluded that the Pearl River Delta was moderately polluted by TPH. No statistically significant correlations were observed between the concentrations of TPH in surface water and sediments.

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

    PubMed

    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.

  19. Assessing and classifying plant-related ecological risk under water management scenarios in China's Yellow River Delta Wetlands.

    PubMed

    Yang, Zhifeng; Qin, Yan; Yang, Wei

    2013-11-30

    The Yellow River Delta is one of the most vigorous delta areas in the world. The wetlands in this delta are ecologically important due to their hydrologic attributes and their role as ecotones between terrestrial and aquatic ecosystems. In recent years, the Yellow River Delta Wetlands have gradually shrunk and degraded due to inadequate environmental flows. Water managers have attempted to balance the needs of the environment with the need to protect water supplies for agriculture and urban needs. Despite the need for environmental protection, a broad-scale, integrated way to characterize the degree of ecological stress in the wetlands has been lacking to date. To provide a framework for evaluating various potential water regimes, we developed a model that can be used to estimate the ecological risk for wetland plants, and used the model to determine the degree of ecological risk for different soil moisture conditions based on an ecological value at risk model that we developed and the fuzzy clustering method. The results revealed the spatial distribution of areas with high, medium, or low risks associated with water stress in the study area. These results can serve as a preliminary template to guide managers in their evaluation of water stress-related risk.

  20. Natural and anthropogenic emissions of N and P to the Parnaíba River Delta in NE Brazil

    NASA Astrophysics Data System (ADS)

    de Paula Filho, Francisco José; Marins, Rozane Valente; de Lacerda, Luiz Drude

    2015-12-01

    The Parnaiba River Delta is the largest open sea delta in the Americas, having a unique ecological importance for the conservation of wildlife and fisheries resources. However, little is known about the biogeochemistry of this ecosystem. This study estimates N and P emissions to the delta using emissions factors, calibrated with field samples and N and P concentrations in different compartments of the delta. The estimated loads totaled 14.517 t N year-1 and 8.748 t P year-1, indicating that anthropogenic N and P emissions outweigh natural emissions by approximately 5 and 10 times, respectively. The activities that contribute the most to this result are livestock farming, agriculture and the release of untreated domestic sewage. The flows of N and P from the estimated loads corresponded to 339 kg N km-2 year-1 and 204 kg P km-2 year-1, so the region can be classified as "meso-active" and "eury-active" with regard to the transfer of nutrients. These results are consistent with the coastal megabasin design (COSCATs) proposed by Meyback et al. (2006). This article presents a first approach to the calculation of an estimated annual emissions inventory of N and P for the lower basin of the Parnaíba River and its coastal region, representing an approach that has been satisfactorily used in assessing the sensitivity of estuarine systems in northeastern Brazil.

  1. Assessing and classifying plant-related ecological risk under water management scenarios in China's Yellow River Delta Wetlands.

    PubMed

    Yang, Zhifeng; Qin, Yan; Yang, Wei

    2013-11-30

    The Yellow River Delta is one of the most vigorous delta areas in the world. The wetlands in this delta are ecologically important due to their hydrologic attributes and their role as ecotones between terrestrial and aquatic ecosystems. In recent years, the Yellow River Delta Wetlands have gradually shrunk and degraded due to inadequate environmental flows. Water managers have attempted to balance the needs of the environment with the need to protect water supplies for agriculture and urban needs. Despite the need for environmental protection, a broad-scale, integrated way to characterize the degree of ecological stress in the wetlands has been lacking to date. To provide a framework for evaluating various potential water regimes, we developed a model that can be used to estimate the ecological risk for wetland plants, and used the model to determine the degree of ecological risk for different soil moisture conditions based on an ecological value at risk model that we developed and the fuzzy clustering method. The results revealed the spatial distribution of areas with high, medium, or low risks associated with water stress in the study area. These results can serve as a preliminary template to guide managers in their evaluation of water stress-related risk. PMID:24095790

  2. Sectorial Water Use Trends in the Urbanizing Pearl River Delta, China

    PubMed Central

    Yao, Mingtian; Werners, Saskia E.; Hutjes, Ronald W. A.; Kabat, Pavel; Huang, Heqing

    2015-01-01

    Assessing and managing water use is crucial for supporting sustainable river basin management and regional development. The first consistent and comprehensive assessment of sectorial water use in the Pearl River Delta (PRD) is presented by analysing homogenized annual water use data from 2000 to 2010 in relation to socio economic statistics for the same period. An abstraction of water use, using the concept of water use intensity, and based on equations inspired by those used in global water resource models, is developed to explore the driving forces underlying water use changes in domestic, industrial and agricultural sectors. We do this at both the level of the region as a whole, as well as for the nine cities that constitute the PRD separately. We find that, despite strong population and economic growth, the PRD managed to stabilize its absolute water use by significant improvements in industrial water use intensities, and early stabilisation of domestic water use intensities. Results reveal large internal differentiation of sectorial water use among the cities in this region, with industrial water use intensity varying from -80 to +95% and domestic water use intensity by +/- 30% compared to the PRD average. In general, per capita water use is highest in the cities that industrialised first. Yet, all cities except Guangzhou are expected to approach a saturation value of per capita water use much below what is suggested in recent global studies. Therefore, existing global assessments probably have overestimated future domestic water use in developing countries. Although scarce and uncertain input data and model limitations lead to a high level of uncertainty, the presented conceptualization of water use is useful in exploring the underlying driving forces of water use trends. PMID:25714731

  3. Cost analysis of water and sediment diversions to optimize land building in the Mississippi River delta

    NASA Astrophysics Data System (ADS)

    Kenney, Melissa A.; Hobbs, Benjamin F.; Mohrig, David; Huang, Hongtai; Nittrouer, Jeffrey A.; Kim, Wonsuck; Parker, Gary

    2013-06-01

    Land loss in the Mississippi River delta caused by subsidence and erosion has resulted in habitat loss and increased exposure of settled areas to storm surge risks. There is debate over the most cost-efficient and geomorphologically feasible projects to build land by river diversions, namely, whether a larger number of small, or a lesser number of large, engineered diversions provide the most efficient outcomes. This study uses an optimization framework to identify portfolios of diversions that are efficient for three general restoration objectives: maximize land built, minimize cost, and minimize water diverted. The framework links the following models: (1) a hydraulic water and sediment diversion model that, for a given structural design for a diversion, estimates the volume of water and sediment diverted; (2) a geomorphological land-building model that estimates the amount of land built over a time period, given the volume of water and sediment; and (3) a statistical model of investment cost as a function of diversion depth and width. An efficient portfolio is found by optimizing one objective subject to constraints on achievement of the other two; then by permuting those constraints, we find distinct portfolios that represent trade-offs among the objectives. Although the analysis explores generic relationships among size, cost, and land building (and thus does not consider specific project proposals or locations), the results demonstrate that large-scale land building (>200 km2) programs that operate over a time span of 50 years require deep diversions because of the enhanced efficiency of sand extraction per unit water. This conclusion applies whether or not there are significant scale economies or diseconomies associated with wider and deeper diversions.

  4. Sectorial water use trends in the urbanizing Pearl River Delta, China.

    PubMed

    Yao, Mingtian; Werners, Saskia E; Hutjes, Ronald W A; Kabat, Pavel; Huang, Heqing

    2015-01-01

    Assessing and managing water use is crucial for supporting sustainable river basin management and regional development. The first consistent and comprehensive assessment of sectorial water use in the Pearl River Delta (PRD) is presented by analysing homogenized annual water use data from 2000 to 2010 in relation to socio economic statistics for the same period. An abstraction of water use, using the concept of water use intensity, and based on equations inspired by those used in global water resource models, is developed to explore the driving forces underlying water use changes in domestic, industrial and agricultural sectors. We do this at both the level of the region as a whole, as well as for the nine cities that constitute the PRD separately. We find that, despite strong population and economic growth, the PRD managed to stabilize its absolute water use by significant improvements in industrial water use intensities, and early stabilisation of domestic water use intensities. Results reveal large internal differentiation of sectorial water use among the cities in this region, with industrial water use intensity varying from -80 to +95% and domestic water use intensity by +/- 30% compared to the PRD average. In general, per capita water use is highest in the cities that industrialised first. Yet, all cities except Guangzhou are expected to approach a saturation value of per capita water use much below what is suggested in recent global studies. Therefore, existing global assessments probably have overestimated future domestic water use in developing countries. Although scarce and uncertain input data and model limitations lead to a high level of uncertainty, the presented conceptualization of water use is useful in exploring the underlying driving forces of water use trends. PMID:25714731

  5. Organochlorines in sediments and mussels collected from coastal sites along the Pearl River Delta, South China.

    PubMed

    Fang, Zhan-qiang

    2004-01-01

    The level and pattern of residues of organochlorine pesticide and polychlorinated biphenyls(PCBs) were analyzed in sediment and mussel (Perna viridis) samples from ten coastal sites along the Pearl River Delta, South China. The range of total HCH was < 0.01 to 0.29 ng/g freeze-dried weight in sediment, and < 0.01 to 1.35 ng/g lipid weight in mussels. Average total DDTs concentrations ranged from < 0.01 to 1.04 ng/g in sediment, and < 0.01 to 148.5 ng/g in mussels. Average total PCB concentrations ranged from 16.4 to 198.6 ng/g in sediment, and from 41 to 729.2 ng/g in mussels. Organochlorine pesticide and PCBs in mussels and sediments presented similar distribution patterns. The regression analysis indicated that PCBs concentrations in mussels were significantly correlated (p < 0.01) with concentrations in sediments. However, their concentrations in mussels were several times higher than the concentration detected in surrounding sediments. The major fraction of DDT related compounds measured in mussels and sediments was DDD. Based on average PCB concentrations, penta-, hexa-, and tetrachlorobiphenyls were preferentially accumulated by mussels as compared to the average sediment composition. According to the present results,three organochlorine polluted "hot spot" sites, including Victoria Harbour, Lingding Yang and Huangmao Sea, were found in the Pearl River estuarine zone. HCHs, DDTs and PCBs in all mussel samples were below the limits of 2, 0.2 and 5.0 microg/g wet weight recommended by the Technical Group of Guangdong Coastal Zone Resource Comprehensive Survey and U. S. Food and Drug Administration.

  6. Ecological consequences for swamp forests of geomorphological development in the Mississippi River Delta as recorded in baldcypress tree rings

    NASA Astrophysics Data System (ADS)

    Keim, Richard

    2010-05-01

    Over the past 200 years, the Mississippi River Delta has been converted from a free-slowing fluvial system with diffuse distribution of fresh water and sediments to a regulated system where flow is concentrated and large areas of wetland are isolated from river inputs and subject to land subsidence. Site-specific research has documented localized effects of these changes on wetland ecological functions, but predicting ecological responses at large scales to future river management and climate change requires assessing the relative importance of multiple hydrological and climatological variables across the range of ecosystem conditions. This work uses 17 baldcypress tree-ring chronologies from across the delta to describe responses of swamp forests to historical changes linked to geomorphological and hydrological changes. Swamps isolated from riverine inputs experienced decreased productivity and mortality because of stagnant flooding or saltwater intrusion. Swamps where river flow is concentrated generally experienced increased growth, but conversion to other ecotypes is hastened by deep flooding or rapid aggradation. The most rapid changes occurred during mutli-year droughts and flooding cycles; these episodic stresses were reversible only when swamps were connected to periodic riverine inputs. Increasing connectivity and aggradation using river diversions appears to be required if swamp forests are to be maintained against rising sea level.

  7. Distribution and condition of larval and juvenile Lost River and shortnose suckers in the Williamson River Delta restoration project and Upper Klamath Lake, Oregon

    USGS Publications Warehouse

    Burdick, Summer M.

    2012-01-01

    Federally endangered Lost River sucker (Deltistes luxatus) and shortnose sucker (Chasmistes brevirostris) were once abundant throughout their range but populations have declined. They were extirpated from several lakes in the 1920s and may no longer reproduce in other lakes. Poor recruitment to the adult spawning populations is one of several reasons cited for the decline and lack of recovery of these species and may be the consequence of high mortality during juvenile life stages. High larval and juvenile sucker mortality may be exacerbated by an insufficient quantity of suitable or high-quality rearing habitat. In addition, larval suckers may be swept downstream from suitable rearing areas in Upper Klamath Lake into Keno Reservoir, where they are assumed lost to Upper Klamath Lake populations. The Nature Conservancy flooded about 3,600 acres (1,456 hectares) to the north of the Williamson River mouth (Tulana) in October 2007, and about 1,400 acres (567 hectares) to the south and east of the Williamson River mouth (Goose Bay Farms) in October 2008, in order to retain larval suckers in Upper Klamath Lake, create nursery habitat, and improve water quality. The U.S. Geological Survey joined a long-term research and monitoring program in collaboration with The Nature Conservancy, the Bureau of Reclamation, and Oregon State University in 2008 to assess the effects of the Williamson River Delta restoration on the early life-history stages of Lost River and shortnose suckers. The primary objectives of the research were to describe habitat colonization and use by larval and juvenile suckers and non-sucker fishes and to evaluate the effects of the restored habitat on the health and condition of juvenile suckers. This report summarizes data collected in 2010 by the U.S. Geological Survey as a part of this monitoring effort and follows two annual reports on data collected in 2008 and 2009. Restoration modifications made to the Williamson River Delta appeared to provide

  8. Extensive organohalogen contamination in wildlife from a site in the Yangtze River Delta.

    PubMed

    Zhou, Yihui; Asplund, Lillemor; Yin, Ge; Athanassiadis, Ioannis; Wideqvist, Ulla; Bignert, Anders; Qiu, Yanling; Zhu, Zhiliang; Zhao, Jianfu; Bergman, Åke

    2016-06-01

    The environmental and human health concerns for organohalogen contaminants (OHCs) extend beyond the 23 persistent organic pollutants (POPs) regulated by the Stockholm Convention. The current, intense industrial production and use of chemicals in China and their bioaccumulation makes Chinese wildlife highly suitable for the assessment of legacy, novel and emerging environmental pollutants. In the present study, six species of amphibians, fish and birds were sampled from paddy fields in the Yangtze River Delta (YRD) were screened for OHCs. Some extensive contamination was found, both regarding number and concentrations of the analytes, among the species assessed. High concentrations of chlorinated paraffins were found in the snake, Short-tailed mamushi (range of 200-340 μg g(-)(1)lw), Peregrine falcon (8-59 μg g(-1)lw) and Asiatic toad (97 μg g(-)(1)lw). Novel contaminants and patterns were observed; octaCBs to decaCB made up 20% of the total polychlorinated biphenyls (PCBs) content in the samples and new OHCs, substituted with 5-8 chlorines, were found but are not yet structurally confirmed. In addition, Dechlorane 602 (DDC-DBF) and numerous other OHCs (DDTs, hexachlorocyclohexanes (HCHs), polybrominated diphenyl ethers (PBDEs), hexbromocyclododecane (HBCDD), chlordane, heptachlor, endosulfan and Mirex) were found in all species analyzed. These data show extensive chemical contamination of wildlife in the YRD with a suite of OHCs with both known and unknown toxicities, calling for further in-depth studies.

  9. [Formation causes of wind damage to Robinia pseudoacacia plantation in Yellow River Delta].

    PubMed

    Cao, Bang-Hua; Zhang, Yu-Juan; Mao, Pei-Li; Li, Cheng-Bo

    2012-08-01

    Based on the investigation of the gale-caused damage to the Robinia pseudoacacia plantation in the Yellow River Delta in June-July 2010, this paper measured the morphological indexes and root system characteristics of fallen trees, gap sizes, and soil compactness, aimed to analyze the formation causes of the wind damage to the plantation. Wind-falling was the main form of the wind damage to the R. pseudoacacia plantation, and the damage was more serious for the trees with the diameter at breast height of 15-20 cm. For the fallen trees, their tree height and their crown width, height, and taper degree increased significantly with the increase of the diameter at breast height, while the height under branch, the ratio of crown width to height, and the ratio of the height under branch to tree height showed no significant change. With the increase of diameter class, root length had a rapid increase first but a slow increase then, while root mass increased gradually. With increasing forest gap area, the number of fallen trees decreased after an initial increase, being the maximum in the gap areas of 100-150 m2. Soil compactness increased with soil depth, but did not show significant changes with the stand diameter class. Increased tree shape factors and suppressed root growth resulting from the increased diameter could be the main factors causing wind-falling, and forest gap played a promotion role. PMID:23189678

  10. Vegetation pattern in shell ridge island in China's Yellow River Delta

    NASA Astrophysics Data System (ADS)

    Zhao, Yanyun; Hu, Xiangming; Liu, Jingtao; Lu, Zhaohua; Xia, Jiangbao; Tian, Jiayi; Ma, Junsheng

    2015-09-01

    In general, coastal habitat conditions are extremely harsh, with the ecological equilibrium inextricably related to the plant community. Understanding the natural vegetation features of a coastal zone with little human disturbance could provide a reference for future vegetation restoration and ecosystem maintenance services. In this study, the vegetation patterns of Wangzi Shell Ridge Island in the Yellow River Delta were investigated. A total of 35 taxa of vascular plants were documented, representing 15 families and 33 genera (of which most were mono-specific). Surveys identified only one to eight taxa in each plot. From sea to land, the vegetation showed a typical zonal distribution pattern. There was a correlation between the landform and important factors that influenced the plants including soil factors and distance from the sea. Thus, the taxa distribution and vegetation had a significant correlation with landform. The dune crest, backdune and interdune lowlands were areas with weak storm surges and were the important locations for the taxa to be become established. Plants along the high-tide line formed important defenses from large waves and high winds. The significant protection provided a suitable living environment for many organisms with high medicinal value. Special attention and protection could be provided to this area by reducing the use of the beach road and enclosing the complete section from sea to land with a protective fence. In addition, vegetation protection and restoration on Shell Ridge Island would aid in the formulation and implementation of reintroduction strategies for similar vegetation in similar habitats.

  11. Status of POPs accumulation in the Yellow River Delta: From distribution to risk assessment.

    PubMed

    Li, Jing; Chen, Chunli; Li, Fadong

    2016-06-15

    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. PMID:27085594

  12. [Impact of urbanization on vegetation phenology in major cities in Yangtze River Delta region].

    PubMed

    Han, Gui-feng; Xu, Jian-hua; Yuan, Xing-zhong

    2008-08-01

    Based on the time series NDVI images from 1998 to 2005 and by the method of moving average, the vegetation phenology in urban areas and buffer zones of Shanghai, Hangzhou, Nanjing, Changzhou, Wuxi and Suzhou in Yangtze River Delta region were calculated. The difference of average phenology in urban areas and buffer zones was analyzed, and the relationship between this difference and the distance away from urban edge was studied. The results showed that in 1998-2005, the urbanization of the cities made the vegetations in their urban area had an earlier start of growing season (SOS), later end of growing season (EOS), longer growing season length (GSL), and smaller NDVIamp (difference of maximal and minimal NDVI in a year). These changes were more obvious in buffer zones if they were closer to urban area. In general, urbanization made the SOS within 4 kilometers away from the urban edge started obviously earlier, and the EOS, GSL and NDVIamp within 10 kilometers away from the urban edge changed obviously. The differences of GSL between urban and buffer zones had a significant logarithmic relationship with the distance away from the urban edge, so did the NDVIamp.

  13. Humpback Dolphins in Hong Kong and the Pearl River Delta: Status, Threats and Conservation Challenges.

    PubMed

    Karczmarski, Leszek; Huang, Shiang-Lin; Or, Carmen K M; Gui, Duan; Chan, Stephen C Y; Lin, Wenzhi; Porter, Lindsay; Wong, Wai-Ho; Zheng, Ruiqiang; Ho, Yuen-Wa; Chui, Scott Y S; Tiongson, Angelico Jose C; Mo, Yaqian; Chang, Wei-Lun; Kwok, John H W; Tang, Ricky W K; Lee, Andy T L; Yiu, Sze-Wing; Keith, Mark; Gailey, Glenn; Wu, Yuping

    2016-01-01

    In coastal waters of the Pearl River Delta (PRD) region, the Indo-Pacific humpback dolphin (Sousa chinensis) is thought to number approximately 2500 individuals. Given these figures, the putative PRD population may appear strong enough to resist demographic stochasticity and environmental pressures. However, living in close proximity to the world's busiest seaport/airport and several densely populated urban centres with major coastal infrastructural developments comes with challenges to the long-term survival of these animals. There are few other small cetacean populations that face the range and intensity of human-induced pressures as those present in the PRD and current protection measures are severely inadequate. Recent mark-recapture analyses of the animals in Hong Kong waters indicate that in the past two decades the population parameters have not been well understood, and spatial analyses show that only a very small proportion of the dolphins' key habitats are given any form of protection. All current marine protected areas within the PRD fail to meet a minimum habitat requirement that could facilitate the population's long-term persistence. Demographic models indicate a continuous decline of 2.5% per annum, a rate at which the population is likely to drop below the demographic threshold within two generations and lose 74% of the current numbers within the lifespan of three generations. In Hong Kong, the case of humpback dolphins represents a particularly explicit example of inadequate management where a complete revision of the fundamental approach to conservation management is urgently needed.

  14. Source apportionment and health effect of NOx over the Pearl River Delta region in southern China.

    PubMed

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

    2016-05-01

    As one of the most notorious atmospheric pollutants, NOx 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 NOx 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 NOx 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 NOx sources, accounting for 30.8% and 18.5% of local NOx sources, respectively. In Hong Kong, marine emissions contributed around 43.4% of local NOx in 2011. Regional transport is another important source of this pollutant, especially in February and November, and it can contribute over 30% of ambient NOx 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 NOx in the Pearl River Delta region. Our results suggest that local governments should combine their efforts and vigorously promote further reduction of NOx emissions, especially for those sources that make a substantial contribution to NOx emissions and affect human health: HDDV, LDGV, industrial point sources and marine sources.

  15. [Major Air Pollutant Emissions of Coal-Fired Power Plant in Yangtze River Delta].

    PubMed

    Ding, Qing-qing; Wei, Wei; Shen, Qun; Sun, Yu-han

    2015-07-01

    The emission factor method was used to estimate major air pollutant emissions of coal-fired power plant in the Yangtze River Delta (YRD) region of the year 2012. Results showed that emissions of SO2, NOx, dust, PM10, PM2.5 were respectively 473 238, 1 566 195, 587 713, 348 773 and 179 820 t. For SO2 and NOx, 300 MW and above class units made contributions of 85% and 82% in emission; while in the respect of dust, PM10 and PM2.5 contribution rates of 100 MW and below class units were respectively 81%, 53% and 40%. Considering the regional distribution, Jiangsu discharged the most, followed by Zhejiang, Shanghai. According to discharge data of several local power plants, we also calculated and made a comparative analysis of emission factors in different unit levels in Shanghai, which indicated a lower emission level. Assuming an equal level was reached in whole YRD, SO2 emission would cut down 55. 8% - 65. 3%; for NOx and dust emissions were 50. 5% - 64. 1% and 3. 4% - 11. 3%, respectively. If technologies and pollution control of lower class units were improved, the emission cuts would improve. However, according to the pollution realities of YRD, we suggested to make a multiple-cuts plan, which could effectively improve the reaional atmospheric environment. PMID:26489303

  16. Public health and medical care for the world's factory: China's Pearl River Delta Region

    PubMed Central

    2011-01-01

    While the growth of urbanization, worldwide, has improved the lives of migrants from the hinterland, it also raises health risks related to population density, concentrated poverty and the transmission of infectious disease. Will megacity regions evolve into socially infected breeding grounds for the rapid transmission of disease, or can they become critical spatial entities for the protection and promotion of population health? We address this question for the Pearl River Delta Region (PRD) based on recent data from Chinese sources, and on the experience of how New York, Greater London, Tokyo and Paris have grappled with the challenges of protecting population health and providing their populations with access to health care services. In some respects, there are some important lessons from comparative experience for PRD, notably the importance of covering the entire population for health care services and targeting special programs for those at highest risk for disease. In other respects, PRD's growth rate and sheer scale make it a unique megacity region that already faces new challenges and will require new solutions. PMID:21968214

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

    NASA Astrophysics Data System (ADS)

    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.

  18. Geochemical evolution of groundwater in the Western Delta region of River Godavari, Andhra Pradesh, India

    NASA Astrophysics Data System (ADS)

    Nageswara Rao, P. V.; Appa Rao, S.; Subba Rao, N.

    2015-06-01

    The present study on geochemical evolution of groundwater is taken up to assess the controlling processes of water chemistry in the Western Delta region of the River Godavari (Andhra Pradesh), which is one of the major rice-producing centers in India. The study region is underlain by coarse sand with black clay (buried channels), black silty clay of recent origin (floodplain) and gray/white fine sand of modern beach sediment of marine source (coastal zone), including brown silty clay with fine sand (paleo-beach ridges). Groundwater is mostly brackish and very hard. It is characterized by Na+ > Mg2+ > Ca2+:HCO3 - > Cl- > SO4 2- > NO3 -, Na+ > Mg2+ > Ca2+:Cl- > HCO3 - > SO4 2-, and Mg2+ > Na+ > Ca2+ > or < K+:HCO3 - > Cl- > or > SO4 2- facies. The ionic relations (Ca2+ + Mg2+:HCO3 -, Ca2+ + Mg2+:SO4 2- + HCO3 -, Na+ + K+:TC, Na+ + K+:Cl- + SO4 2-, HCO3 -:TC, HCO3 -:Ca2+ + Mg2+, Na+:Cl- and Na+:Ca2+) indicate that the rock weathering, mineral dissolution, evaporation and ion exchange are the processes to control the aquifer chemistry. Anthropogenic and marine sources are also the supplementary factors for brackish water quality. These observations are further supported by Gibbs mechanisms that control the water chemistry. Thus, the study suggests that the initial quality of groundwater of geogenic origin has been subsequently modified by the influences of anthropogenic and marine sources.

  19. Gender relations and sexual communication among female students in the Mekong River Delta of Vietnam.

    PubMed

    Bui, Thanh Cong; Diamond, Pamela M; Markham, Christine; Ross, Michael W; Nguyen-Le, Thanh-An; Tran, Ly Hai Thi

    2010-08-01

    Young women's ability to pursue a safer-sex life in line with their wishes is crucial to their sexual health. Although some previous observations have suggested that young women's lack of ability to negotiate safer sex is due to gender power imbalances in the culture of Vietnam, studies that have tested this hypothesis explicitly and quantitatively are few and far between. The present study aimed to test the association between perceived gender relations and perceived self-efficacy in communicating sexual matters among undergraduate female students in the Mekong River Delta of Vietnam. The analysis involved secondary data from 260 subjects from a larger survey regarding gender equity. Structural equation modeling was used to examine the study's hypothesis. Results showed that adherence to traditional gender roles and norms was significantly associated with female students' reduced self-efficacy to communicate on safer-sex matters, such as refusing unwanted sex or requesting condom use. This association remained invariant in the cross-validation process between partnered and unpartnered groups. Programmes that aim to promote safer-sex negotiation and practices for this population may need to address the influence of gender relations and power.

  20. Weekend effect of temperature variation in the Yangtze River delta of China

    NASA Astrophysics Data System (ADS)

    Ma, Li; Jiang, Zhihong; Duan, Chunfeng; Miao, Qilong; Wang, Yong

    2009-03-01

    Study is performed of the weekly cycle of temperature indices (its diurnal range, mean, maximum and minimum) as well as cloudiness, solar radiation and air pollution index based on 1996-2005 surface observations and air pollution indexes from four big cities over the Yangtze River Delta of China. Results suggest that these temperature variations are featured by significant weekend effect (WE) in that these temperatures are higher at weekends than on workdays in summer as opposed to those in other seasons; the WE of diurnal maximum and minimum temperatures is much bigger at weekends and can be utilized as the WE index; during the long spell of holidays or festivities in China WE is remarkable, and especially in the Spring Festival and National Day holidays these temperatures are smaller compared to those 7 day before and after as opposed to the values during, and 7 days before/after, the May Day holidays; the temperature WE bears a close relation to aerosol concentration thanks to anthropogenic activities; in summer the indirect impacts of aerosols (aerosol - cloud interactions) due to abundant vapor play a dominant role and at weekends little aerosol is responsible for reduced cloudiness, allowing more solar radiation to strike the ground for the rise in all the temperatures; in the other seasons the direct and semi-direct effect of aerosol plays a predominant part, with the concentration of aerosols declining at weekends for reducing its ability to heat air and increasing cloudiness, thus leading to the decrease in all the temperature elements.

  1. Seasonality in polybrominated diphenyl ether concentrations in the atmosphere of the Yangtze River Delta, China.

    PubMed

    Zhang, Lifei; Dong, Liang; Huang, Yeru; Shi, Shuangxin; Yang, Wenlong; Zhou, Li

    2016-05-01

    Polybrominated diphenyl ether (PBDE) concentrations in the atmosphere in rapidly developing parts of China have been studied little. In this study, polyurethane foam disk passive air samplers were used to comprehensively investigate PBDE concentrations in the atmosphere of the Yangtze River Delta in different seasons in 2010 and 2011. The mean sum of the concentrations of 13 PBDE congeners was 3.3 pg/m(3) in spring, 7.3 pg/m(3) in summer, 1.0 pg/m(3) in autumn, and 12 pg/m(3) in winter. Higher PBDE concentrations were found in urban areas than in rural areas. The PBDE concentrations were comparable to concentrations that have been found in cities around the world. BDE28, BDE47, BDE99, BDE153, and BDE183 were the dominant PBDE congeners in all seasons. High PBDE concentrations were found in satellite cities, such as Changshu, Wujiang, and Zhangjiagang, suggesting that commercial PBDEs (including pentabromodiphenyl ether products) are produced and/or used in those cities. The PBDE concentrations in the atmosphere were used to estimate daily doses through the inhalation of outdoor air. The most severe risks posed by exposure to PBDEs were found to occur in winter, for both adults and children, but the PBDE concentrations were found not to pose appreciable risks to human health. PMID:26791420

  2. Remote identification of maternal polar bear (Ursus maritimus) denning habitat on the Colville River Delta, Alaska

    NASA Astrophysics Data System (ADS)

    Blank, Justin J.

    High resolution digital aerial photographs (1 foot pixel size) of the Colville River Delta, Alaska were examined in 3D, with the use of a digital photogrammetric workstation. Topographic features meeting the criteria required for adequate snow accumulation, and subsequent construction of terrestrial polar bear maternal dens, were identified and digitized into an ArcGIS line shapefile. Effectiveness, efficiency, and accuracy were improved when compared to previous polar bear denning habitat efforts which utilized contact photo prints and a pocket stereoscope in other geographic areas of northern Alaska. Accuracy of photograph interpretation was systematically evaluated visually from the air with the use of a helicopter and physically on the ground. Results show that the mapping efforts were successful in identifying den habitat 91.3% of the time. Knowledge denning habitat can improve and inform decision making by managers and regulators when considering travel and development in the study area. An understanding of polar bear denning habitat extent and location will be a crucial tool for planning activities within the study area in a way that minimizes conflicts with maternal dens.

  3. Regional dynamics of persistent organic pollutants (POPs) in the Pearl River Delta, China: implications and perspectives.

    PubMed

    Zhang, Kai; Zhang, Bao-Zhong; Li, Shao-Meng; Zeng, Eddy Y

    2011-10-01

    The mass transport budgets of 1,1,1-trichloro-2,2-bis(chlorophenyl)ethane (p,p'-DDT) and decabromodiphenyl ether (BDE-209) in the Pearl River Delta, South China were calculated based on previously collected data. Residual p,p'-DDT, mostly related to historical use, has largely settled into soil (780,000 kg), while the soil BDE-209 inventory (44,000 kg) is considerably smaller. Conversely, large amounts of BDE-209 currently used in numerous commercial products have resulted in a much higher atmospheric depositional flux of BDE-209 (28,100 kg/yr) relative to p,p'-DDT (310 kg/yr). The soil inventory of p,p'-DDT is predicted to decrease to half of its current value after 22 years, and the percent area containing soil p,p'-DDT at levels exceeding the effects range-medium (27 ng/g) will decrease from 40% to 20%. Finally, soil BDE-209 inventory will reach an equilibrium value of 940 tons in ~60 years, when BDE-209 levels in 50% of soil will be above an equivalent risk guideline value (125 ng/g). PMID:21669481

  4. Dynamics of soil organic and inorganic carbon in the cropland of upper Yellow River Delta, China

    PubMed Central

    Guo, Yang; Wang, Xiujun; Li, Xianglan; Wang, Jiaping; Xu, Minggang; Li, Dongwei

    2016-01-01

    Soil inorganic carbon (SIC) and organic carbon (SOC) are important carbon reservoirs in terrestrial ecosystems. However, little attention was paid to SIC dynamics in cropland. We conducted a survey in the upper Yellow River Delta of North China Plain. We collected 155 soil samples from 31 profiles, and measured SOC, SIC and soluble Ca2+ and Mg2+ contents. Our results showed that mean SOC content decreased from 9.30 g kg−1 near the surface to 2.36 g kg−1 in 80–100 cm whereas mean SIC content increased from 10.48 to 12.72 g kg−1. On average, SOC and SIC stocks over 0–100 cm were 5.73 kg C m−2 and 16.89 kg C m−2, respectively. There was a significantly positive correlation (r = 0.88, P < 0.001) between SOC and SIC in the cropland. We also found that SIC had a significantly positive correlation with both soluble Ca2+ (r = 0.57, P < 0.01) and Mg2+ (r = 0.43, P < 0.05). Our study suggested that increasing SOC might lead to an increase in SIC stocks in the cropland of North China Plain. This study highlights the importance of SIC in the carbon cycle of China’s semi-arid region. PMID:27782204

  5. [Modeling Study of A Typical Summer Ozone Pollution Event over Yangtze River Delta].

    PubMed

    Zhang, Liang; Zhu, Bin; Gao, Jin-hui; Kang, Han-qing; Yang, Peng; Wang, Hong-lei; Li, Yue-e; Shao, Ping

    2015-11-01

    WRF/Chem model was used to analyze the temporal and spatial distribution characteristics and physical and chemical mechanism of a typical summer ozone pollution event over Yangtze River Delta (YRD). The result showed that the model was capable of reproducing the temporal and spatial distribution and evolution characteristics of the typical summer ozone pollution event over YRD. The YRD region was mainly affected by the subtropical high-pressure control, and the weather conditions of sunshine, high temperature and small wind were favorable for the formation of photochemical pollution on August 10-18, 2013. The results of simulation showed that the spatial and temporal distribution of O3 was obviously affected by the meteorological fields, geographic location, regional transport and chemical formation over YRD. The sensitivity experiment showed that the O3 concentration affected by maritime airstream was low in Shanghai, but the impact of Shanghai emissions on the spatial and temporal distribution of O3 concentration over YRD was significant; The main contribution of the high concentration of O3 in Nanjing surface was chemical generation ( alkene and aromatic) and the vertical transport from high-altitude O3, whereas the main contribution of the high concentration of O3 in Hangzhou and Suzhou was physics process. The influence of the 15:00 peak concentration of O3 over YRD was very obvious when O3 precursor was reduced at the maximum O3 formation rate (11-13 h).

  6. [Formation causes of wind damage to Robinia pseudoacacia plantation in Yellow River Delta].

    PubMed

    Cao, Bang-Hua; Zhang, Yu-Juan; Mao, Pei-Li; Li, Cheng-Bo

    2012-08-01

    Based on the investigation of the gale-caused damage to the Robinia pseudoacacia plantation in the Yellow River Delta in June-July 2010, this paper measured the morphological indexes and root system characteristics of fallen trees, gap sizes, and soil compactness, aimed to analyze the formation causes of the wind damage to the plantation. Wind-falling was the main form of the wind damage to the R. pseudoacacia plantation, and the damage was more serious for the trees with the diameter at breast height of 15-20 cm. For the fallen trees, their tree height and their crown width, height, and taper degree increased significantly with the increase of the diameter at breast height, while the height under branch, the ratio of crown width to height, and the ratio of the height under branch to tree height showed no significant change. With the increase of diameter class, root length had a rapid increase first but a slow increase then, while root mass increased gradually. With increasing forest gap area, the number of fallen trees decreased after an initial increase, being the maximum in the gap areas of 100-150 m2. Soil compactness increased with soil depth, but did not show significant changes with the stand diameter class. Increased tree shape factors and suppressed root growth resulting from the increased diameter could be the main factors causing wind-falling, and forest gap played a promotion role.

  7. Ecological effects of roads on the plant diversity of coastal wetland in the Yellow River Delta.

    PubMed

    Li, Yunzhao; Yu, Junbao; Ning, Kai; Du, Siyao; Han, Guangxuan; Qu, Fanzhu; Wang, Guangmei; Fu, Yuqin; Zhan, Chao

    2014-01-01

    The 26 sample sites in 7 study plots adjacent to asphalt road and earth road in coastal wetland in the Yellow River Delta were selected to quantify plant diversity using quadrat sampling method in plant bloom phase of July and August 2012. The indice of β T and Jaccard's coefficient were applied to evaluate the species diversity. The results showed that the plant diversities and alien plants were high in the range of 0-20 m to the road verge. There were more exotics and halophytes in plots of asphalt roadside than that of earth roadside. However, proportion of halophytes in habitats of asphalt roadsides was lower than that of earth roadside. By comparing β-diversity, there were more common species in the asphalt roadsides than that in the earth roadsides. The similarity of plant communities in studied plots of asphalt roadsides and earth roadsides increased with increasing the distance to road verge. The effect range of roads for plant diversity in study region was about 20 m to road verge. Our results indicate that the construction and maintenance of roads in wetland could increase the plant species diversities of communities and risk of alien species invasion.

  8. Container cargo simulation modeling for measuring impacts of infrastructure investment projects in Pearl River Delta

    NASA Astrophysics Data System (ADS)

    Li, Jia-Qi; Shibasaki, Ryuichi; Li, Bo-Wei

    2010-03-01

    In the Pearl River Delta (PRD), there is severe competition between container ports, particularly those in Hong Kong, Shenzhen, and Guangzhou, for collecting international maritime container cargo. In addition, the second phase of the Nansha terminal in Guangzhou’s port and the first phase of the Da Chang Bay container terminal in Shenzhen opened last year. Under these circumstances, there is an increasing need to quantitatively measure the impact these infrastructure investments have on regional cargo flows. The analysis should include the effects of container terminal construction, berth deepening, and access road construction. The authors have been developing a model for international cargo simulation (MICS) which can simulate the movement of cargo. The volume of origin-destination (OD) container cargo in the East Asian region was used as an input, in order to evaluate the effects of international freight transportation policies. This paper focuses on the PRD area and, by incorporating a more detailed network, evaluates the impact of several infrastructure investment projects on freight movement.

  9. Behavior and reproductive success of rock sandpipers breeding on the Yukon-Kuskokwim river delta, Alaska

    USGS Publications Warehouse

    Johnson, M.; Conklin, J.R.; Johnson, B.L.; McCaffery, B.J.; Haig, S.M.; Walters, J.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 bred at our study site for ???2 years, and among these we did not observe mate change (i.e., when both members of a pair returned and each mated with a new individual). Nests were typically initiated by mid-May and 53% of females laid second clutches if first clutches were lost through mid-June. Males regularly incubated clutches during the morning (0800-1259 hrs AKDT) and afternoon (1300-1759 hrs) and rarely during the evening (1800-2300 hrs), whereas female incubation was relatively consistent throughout the day. Apparent nest success (percent of known nests successfully hatching > 1 chick) among first and second nests was 19 and 44%, respectively (n = 45). A minimum of 44% of hatching nests fledged at least one young. Males cared for young but half of females deserted mate and brood 1-7 days post-hatch. This first description of North American Rock Sandpiper breeding behavior from a color-marked population complements previous work on this species on the Chukotsky Peninsula, Russia.

  10. Arbuscular mycorrhizal status of wild plants in saline-alkaline soils of the Yellow River Delta.

    PubMed

    Wang, Fa-Yuan; Liu, Run-Jin; Lin, Xian-Gui; Zhou, Jian-Min

    2004-04-01

    A survey was made of the arbuscular mycorrhizal (AM) status of five dominant wild plants Tamarix chinensis, Phragmites communis, Suaeda glauca, Aeluropus littoralis var. sinensis and Cirsium setosum in saline-alkaline soils of the Yellow River Delta that show low plant diversity. All of the species were colonized and showed typical AM structures (arbuscules, vesicles). The colonization percentage ranged from 0.2% to 9.5%, where C. setosum was the highest. The species richness of AMF at the different sites ranged from 2.00 to 2.40 per 50 ml soil, with an average of 2.16. Species diversity ranged from 1.99 to 2.22 per 50 ml soil, with an average of 2.13. Spore density ranged from 3 to 30 per 50 ml soil, with an average of 12. Glomus was the dominant genus, with a frequency and relative abundance of 88.1% and 68.4%, respectively. G. caledonium, with a frequency and relative abundance of 15.0% and 4.6%, respectively, was the dominant species. Differences were also observed in the distribution of AMF in different soil layers. Although there were still AM fungal spores in the layer 40 cm below the surface, most spores were found at a depth of 0-40 cm.

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

    PubMed

    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%).

  12. Particulate matter pollution research in the Yangtze River Delta: Observations, processes, modeling and health effects

    NASA Astrophysics Data System (ADS)

    Yu, Jian Zhen; Cao, Junji; Hu, Min; Kan, Haidong; Fu, Tzung-May

    2015-12-01

    The Yangtze River Delta (YRD) covers an area of 110,915 square km, including seven cities of northern Zhejiang Province, the Shanghai municipality and eight cities of southern Jiangsu Province. It is home to ∼110 million people and its GDP accounts for 17.4% of the whole China Economy (Hong Kong Trade Development Council Research, 2013). The YRD economy is greatly driven by heavy industries such as machinery, chemicals and automobile manufacturing. It is also a large producer of agricultural products, including wheat, rice, and corn. Its transport infrastructure is highly developed, with the number of vehicles per km2 higher than that in the developed countries. Two out of the ten top ports in China (Shanghai and Ningbo-Zhoushan ports) are located in the YRD. As a fast-developing and an important economic powerhouse of the Chinese Mainland, worsening of air quality and increasing pollution episodes in this region has led to heightened public health concerns and intensified research.

  13. Fractal features of soil particle size distribution in newly formed wetlands in the Yellow River Delta

    PubMed Central

    Yu, Junbao; Lv, Xiaofei; Bin, Ma; Wu, Huifeng; Du, Siyao; Zhou, Mo; Yang, Yanming; Han, Guangxuan

    2015-01-01

    The characteristic of particle size distribution (PSD) in the newly formed wetlands in coast has seldom been studied. We applied fractal-scaling theory in assessing soil particle size distribution (PSD) features of newly formed wetlands in the Yellow River Delta (YRD), China. The singular fractal dimensions (D) values ranged from 1.82 to 1.90, the capacity dimension (D0) values ranged from 0.84 to 0.93, and the entropy dimension (D1) values ranged from 0.66 to 0.84. Constrained corresponding analysis revealed that 43.5% of the variance in soil PSD can be explained by environmental factors, including 14.7% by seasonal variation, 8.6% by soil depth, and 8.0% by vegetation type. The fractal dimensions D and D1 were sensitive with fine particles with size ranging less than 126 μm, and D0 was sensitive with coarse particles with size ranging between 126 μm to 2000 μm. Fractal analysis makes full use of soil PSD information, and offers a useful approach to quantify and assess the soil physical attributes in the newly formed wetland. PMID:26014107

  14. Changes of Soil Particle Size Distribution in Tidal Flats in the Yellow River Delta

    PubMed Central

    Lyu, Xiaofei; Yu, Junbao; Zhou, Mo; Ma, Bin; Wang, Guangmei; Zhan, Chao; Han, Guangxuan; Guan, Bo; Wu, Huifeng; Li, Yunzhao; Wang, De

    2015-01-01

    Background The tidal flat is one of the important components of coastal wetland systems in the Yellow River Delta (YRD). It can stabilize shorelines and protect coastal biodiversity. The erosion risk in tidal flats in coastal wetlands was seldom been studied. Characterizing changes of soil particle size distribution (PSD) is an important way to quantity soil erosion in tidal flats. Method/Principal findings Based on the fractal scale theory and network analysis, we determined the fractal characterizations (singular fractal dimension and multifractal dimension) soil PSD in a successional series of tidal flats in a coastal wetland in the YRD in eastern China. The results showed that the major soil texture was from silt loam to sandy loam. The values of fractal dimensions, ranging from 2.35 to 2.55, decreased from the low tidal flat to the high tidal flat. We also found that the percent of particles with size ranging between 0.4 and 126 μm was related with fractal dimensions. Tide played a great effort on soil PSD than vegetation by increasing soil organic matter (SOM) content and salinity in the coastal wetland in the YRD. Conclusions/Significance Tidal flats in coastal wetlands in the YRD, especially low tidal flats, are facing the risk of soil erosion. This study will be essential to provide a firm basis for the coast erosion control and assessment, as well as wetland ecosystem restoration. PMID:25816240

  15. [Major Air Pollutant Emissions of Coal-Fired Power Plant in Yangtze River Delta].

    PubMed

    Ding, Qing-qing; Wei, Wei; Shen, Qun; Sun, Yu-han

    2015-07-01

    The emission factor method was used to estimate major air pollutant emissions of coal-fired power plant in the Yangtze River Delta (YRD) region of the year 2012. Results showed that emissions of SO2, NOx, dust, PM10, PM2.5 were respectively 473 238, 1 566 195, 587 713, 348 773 and 179 820 t. For SO2 and NOx, 300 MW and above class units made contributions of 85% and 82% in emission; while in the respect of dust, PM10 and PM2.5 contribution rates of 100 MW and below class units were respectively 81%, 53% and 40%. Considering the regional distribution, Jiangsu discharged the most, followed by Zhejiang, Shanghai. According to discharge data of several local power plants, we also calculated and made a comparative analysis of emission factors in different unit levels in Shanghai, which indicated a lower emission level. Assuming an equal level was reached in whole YRD, SO2 emission would cut down 55. 8% - 65. 3%; for NOx and dust emissions were 50. 5% - 64. 1% and 3. 4% - 11. 3%, respectively. If technologies and pollution control of lower class units were improved, the emission cuts would improve. However, according to the pollution realities of YRD, we suggested to make a multiple-cuts plan, which could effectively improve the reaional atmospheric environment.

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

    PubMed

    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%). PMID:26414850

  17. Relationship of urinary arsenic metabolites to intake estimates in residents of the Red River Delta, Vietnam.

    PubMed

    Agusa, Tetsuro; Kunito, Takashi; Minh, Tu Binh; Kim Trang, Pham Thi; Iwata, Hisato; Viet, Pham Hung; Tanabe, Shinsuke

    2009-02-01

    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 microg/L. Remarkably, 86% of groundwater samples exceeded WHO drinking water guideline of 10 microg/L. Also, estimated inorganic As intake from groundwater and rice were over Provisional Tolerable Weekly Intake (15 microg/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.

  18. Winter soil respiration from different vegetation patches in the Yellow River Delta, China.

    PubMed

    Han, Guangxuan; Yu, Junbao; Li, Huabing; Yang, Liqiong; Wang, Guangmei; Mao, Peili; Gao, Yongjun

    2012-07-01

    Vegetation type and density exhibited a considerable patchy distribution at very local scales in the Yellow River Delta, due to the spatial variation of soil salinity and water scarcity. We proposed that soil respiration is affected by the spatial variations in vegetation type and soil chemical properties and tested this hypothesis in three different vegetation patches (Phragmites australis, Suaeda heteroptera and bare soil) in winter (from November 2010 to April 2011). At diurnal scale, soil respiration all displayed single-peak curves and asymmetric patterns in the three vegetation patches; At seasonal scale, soil respiration all declined steadily until February, and then increased to a peak in next April. But, the magnitude of soil respiration showed significant differences among the three sites. Mean soil respiration rates in winter were 0.60, 0.45 and 0.17 μmol CO(2) m(-2) s(-1) for the Phragmites australis, Suaeda heteroptera and bare soil, respectively. The combined effect of soil temperature and soil moisture accounted for 58-68 % of the seasonal variation of winter soil respiration. The mean soil respiration revealed positive and linear correlations with total N, total N and SOC storages at 0-20 cm depth, and plant biomass among the three sites. We conclude that the patchy distribution of plant biomass and soil chemical properties (total C, total N and SOC) may affect decomposition rate of soil organic matter in winter, thereby leading to spatial variations in soil respiration. PMID:22576142

  19. [Structure and dynamics of the mangrove forest in the Rancheria River delta, Colombian Caribbean].

    PubMed

    Lema Vélez, Luisa Fernanda; Polanía, Jaime

    2007-03-01

    We registered seedling survival and biomass increase for Rhizophora mangle L., Avicennia germinans L. and Laguncularia racemosa (L.) Gaertn. f, main mangrove species in the Rancheria River delta, Colombia. Only seedlings of R. mangle were found to survive. We also measured maximum rate of litterfall. We estimated annual litterfall through interpolation within an exponential regression performed with maximum and annual litterfall data published in other sources; the value of annual litterfall for the area was estimated to be 12.9 mgha(-1)y(-1). We found a 7.4 mgha(-1)y(-1)(-1) increase in biomass. Litterfall constitutes the larger fraction of the 20.2 mgha(-1)y(-1) productivity of this mangrove. We believe this is a very high value for a forest under unfavorable natural and human conditions, such as high seasonality and continuous use of the forest to feed goats and sheep. We consider that the high productivity is a response to both natural and anthropogenic stress. PMID:18457110

  20. Winter Soil Respiration from Different Vegetation Patches in the Yellow River Delta, China

    NASA Astrophysics Data System (ADS)

    Han, Guangxuan; Yu, Junbao; Li, Huabing; Yang, Liqiong; Wang, Guangmei; Mao, Peili; Gao, Yongjun

    2012-07-01

    Vegetation type and density exhibited a considerable patchy distribution at very local scales in the Yellow River Delta, due to the spatial variation of soil salinity and water scarcity. We proposed that soil respiration is affected by the spatial variations in vegetation type and soil chemical properties and tested this hypothesis in three different vegetation patches ( Phragmites australis, Suaeda heteroptera and bare soil) in winter (from November 2010 to April 2011). At diurnal scale, soil respiration all displayed single-peak curves and asymmetric patterns in the three vegetation patches; At seasonal scale, soil respiration all declined steadily until February, and then increased to a peak in next April. But, the magnitude of soil respiration showed significant differences among the three sites. Mean soil respiration rates in winter were 0.60, 0.45 and 0.17 μmol CO2 m-2 s-1 for the Phragmites australis, Suaeda heteroptera and bare soil, respectively. The combined effect of soil temperature and soil moisture accounted for 58-68 % of the seasonal variation of winter soil respiration. The mean soil respiration revealed positive and linear correlations with total N, total N and SOC storages at 0-20 cm depth, and plant biomass among the three sites. We conclude that the patchy distribution of plant biomass and soil chemical properties (total C, total N and SOC) may affect decomposition rate of soil organic matter in winter, thereby leading to spatial variations in soil respiration.

  1. Source apportionment and health effect of NOx over the Pearl River Delta region in southern China.

    PubMed

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

    2016-05-01

    As one of the most notorious atmospheric pollutants, NOx 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 NOx 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 NOx 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 NOx sources, accounting for 30.8% and 18.5% of local NOx sources, respectively. In Hong Kong, marine emissions contributed around 43.4% of local NOx in 2011. Regional transport is another important source of this pollutant, especially in February and November, and it can contribute over 30% of ambient NOx 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 NOx in the Pearl River Delta region. Our results suggest that local governments should combine their efforts and vigorously promote further reduction of NOx emissions, especially for those sources that make a substantial contribution to NOx emissions and affect human health: HDDV, LDGV, industrial point sources and marine sources. PMID:26845361

  2. Delaying precipitation and lightning by air pollution over the Pearl River Delta. Part I: Observational analyses

    NASA Astrophysics Data System (ADS)

    Guo, Jianping; Deng, Minjun; Lee, Seoung Soo; Wang, Fu; Li, Zhanqing; Zhai, Panmao; Liu, Huan; Lv, Weitao; Yao, Wen; Li, Xiaowen

    2016-06-01

    The radiative and microphysical effects of aerosols can affect the development of convective clouds. The objective of this study is to reveal if the overall aerosol effects have any discernible impact on the diurnal variations in precipitation and lightning by means of both observational analysis and modeling. As the first part of two companion studies, this paper is concerned with analyzing hourly PM10, precipitation, and lightning data collected during the summers of 2008-2012 in the Pearl River Delta region. Daily PM10 data were categorized as clean, medium, or polluted so that any differences in the diurnal variations in precipitation and lightning could be examined. Heavy precipitation and lightning were found to occur more frequently later in the day under polluted conditions than under clean conditions. Analyses of the diurnal variations in several meteorological factors such as air temperature, vertical velocity, and wind speed were also performed. They suggest that the influence of aerosol radiative and microphysical effects serve to suppress and enhance convective activities, respectively. Under heavy pollution conditions, the reduction in solar radiation reaching the surface delays the occurrence of strong convection and postpones heavy precipitation to late in the day when the aerosol invigoration effect more likely comes into play. Although the effect of aerosol particles can be discernible on the heavy precipitation through the daytime, the influence of concurrent atmospheric dynamics and thermodynamics cannot be ruled out.

  3. Foraging and growth potential of juvenile Chinook Salmon after tidal restoration of a large river delta

    USGS Publications Warehouse

    David, Aaron T.; Ellings, Christopher; Woo, Isa; Simenstad, Charles A.; Takekawa, John Y.; Turner, Kelley L.; Smith, Ashley L.; Takekawa, Jean E.

    2014-01-01

    We evaluated whether restoring tidal flow to previously diked estuarine wetlands also restores foraging and growth opportunities for juvenile Chinook Salmon Oncorhynchus tshawytscha. Several studies have assessed the value of restored tidal wetlands for juvenile Pacific salmon Oncorhynchus spp., but few have used integrative measures of salmon performance, such as habitat-specific growth potential, to evaluate restoration. Our study took place in the Nisqually River delta, Washington, where recent dike removals restored tidal flow to 364 ha of marsh—the largest tidal marsh restoration project in the northwestern contiguous United States. We sampled fish assemblages, water temperatures, and juvenile Chinook Salmon diet composition and consumption rates in two restored and two reference tidal channels during a 3-year period after restoration; these data were used as inputs to a bioenergetics model to compare Chinook Salmon foraging performance and growth potential between the restored and reference channels. We found that foraging performance and growth potential of juvenile Chinook Salmon were similar between restored and reference tidal channels. However, Chinook Salmon densities were significantly lower in the restored channels than in the reference channels, and growth potential was more variable in the restored channels due to their more variable and warmer (2°C) water temperatures. These results indicate that some—but not all—ecosystem attributes that are important for juvenile Pacific salmon can recover rapidly after large-scale tidal marsh restoration.

  4. Seasonality in polybrominated diphenyl ether concentrations in the atmosphere of the Yangtze River Delta, China.

    PubMed

    Zhang, Lifei; Dong, Liang; Huang, Yeru; Shi, Shuangxin; Yang, Wenlong; Zhou, Li

    2016-05-01

    Polybrominated diphenyl ether (PBDE) concentrations in the atmosphere in rapidly developing parts of China have been studied little. In this study, polyurethane foam disk passive air samplers were used to comprehensively investigate PBDE concentrations in the atmosphere of the Yangtze River Delta in different seasons in 2010 and 2011. The mean sum of the concentrations of 13 PBDE congeners was 3.3 pg/m(3) in spring, 7.3 pg/m(3) in summer, 1.0 pg/m(3) in autumn, and 12 pg/m(3) in winter. Higher PBDE concentrations were found in urban areas than in rural areas. The PBDE concentrations were comparable to concentrations that have been found in cities around the world. BDE28, BDE47, BDE99, BDE153, and BDE183 were the dominant PBDE congeners in all seasons. High PBDE concentrations were found in satellite cities, such as Changshu, Wujiang, and Zhangjiagang, suggesting that commercial PBDEs (including pentabromodiphenyl ether products) are produced and/or used in those cities. The PBDE concentrations in the atmosphere were used to estimate daily doses through the inhalation of outdoor air. The most severe risks posed by exposure to PBDEs were found to occur in winter, for both adults and children, but the PBDE concentrations were found not to pose appreciable risks to human health.

  5. Humpback Dolphins in Hong Kong and the Pearl River Delta: Status, Threats and Conservation Challenges.

    PubMed

    Karczmarski, Leszek; Huang, Shiang-Lin; Or, Carmen K M; Gui, Duan; Chan, Stephen C Y; Lin, Wenzhi; Porter, Lindsay; Wong, Wai-Ho; Zheng, Ruiqiang; Ho, Yuen-Wa; Chui, Scott Y S; Tiongson, Angelico Jose C; Mo, Yaqian; Chang, Wei-Lun; Kwok, John H W; Tang, Ricky W K; Lee, Andy T L; Yiu, Sze-Wing; Keith, Mark; Gailey, Glenn; Wu, Yuping

    2016-01-01

    In coastal waters of the Pearl River Delta (PRD) region, the Indo-Pacific humpback dolphin (Sousa chinensis) is thought to number approximately 2500 individuals. Given these figures, the putative PRD population may appear strong enough to resist demographic stochasticity and environmental pressures. However, living in close proximity to the world's busiest seaport/airport and several densely populated urban centres with major coastal infrastructural developments comes with challenges to the long-term survival of these animals. There are few other small cetacean populations that face the range and intensity of human-induced pressures as those present in the PRD and current protection measures are severely inadequate. Recent mark-recapture analyses of the animals in Hong Kong waters indicate that in the past two decades the population parameters have not been well understood, and spatial analyses show that only a very small proportion of the dolphins' key habitats are given any form of protection. All current marine protected areas within the PRD fail to meet a minimum habitat requirement that could facilitate the population's long-term persistence. Demographic models indicate a continuous decline of 2.5% per annum, a rate at which the population is likely to drop below the demographic threshold within two generations and lose 74% of the current numbers within the lifespan of three generations. In Hong Kong, the case of humpback dolphins represents a particularly explicit example of inadequate management where a complete revision of the fundamental approach to conservation management is urgently needed. PMID:26790887

  6. An ozone episode over the Pearl River Delta in October 2008

    NASA Astrophysics Data System (ADS)

    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.

  7. Regional dynamics of persistent organic pollutants (POPs) in the Pearl River Delta, China: implications and perspectives.

    PubMed

    Zhang, Kai; Zhang, Bao-Zhong; Li, Shao-Meng; Zeng, Eddy Y

    2011-10-01

    The mass transport budgets of 1,1,1-trichloro-2,2-bis(chlorophenyl)ethane (p,p'-DDT) and decabromodiphenyl ether (BDE-209) in the Pearl River Delta, South China were calculated based on previously collected data. Residual p,p'-DDT, mostly related to historical use, has largely settled into soil (780,000 kg), while the soil BDE-209 inventory (44,000 kg) is considerably smaller. Conversely, large amounts of BDE-209 currently used in numerous commercial products have resulted in a much higher atmospheric depositional flux of BDE-209 (28,100 kg/yr) relative to p,p'-DDT (310 kg/yr). The soil inventory of p,p'-DDT is predicted to decrease to half of its current value after 22 years, and the percent area containing soil p,p'-DDT at levels exceeding the effects range-medium (27 ng/g) will decrease from 40% to 20%. Finally, soil BDE-209 inventory will reach an equilibrium value of 940 tons in ~60 years, when BDE-209 levels in 50% of soil will be above an equivalent risk guideline value (125 ng/g).

  8. Heavy metal contamination of the Sacca di Goro lagoon area (Po River Delta, Northern Italy)

    NASA Astrophysics Data System (ADS)

    Rapti-Caputo, Dimitra

    2010-05-01

    The lagoon area of the Sacca di Goro, within the Po River delta, is ca. 20 km2 wide, with a mean depth of 1.5 m and a mean salinity of 29%o. It holds a major naturalistic interest as well as an economic one due to the aquaculture activities (mussels and clams). In this lagoon system, the quality of the sea-bottom sediments is crucial not only for the cultivated species, but also for the potential bio-accumulation problems in heavy metals. The definition of the qualitative status of the lagoon sediments is crucial for adopting the best management strategies and the protection of the environmental conditions. We determined the concentration in SiO2, TiO2, Al2O3, Fe2O3, MgO, MnO, CaO, Na2O, K2O, P2O5, Ba, Ce, Co, Cr, La, Nb, Ni, Pb, Rb, Sr, Th, V, Y, Zn, Cu, Ga, Nd, S and Sr, of 31 samples homogeneously collected over the lagoon area. This large dataset allowed i) to define the environmental quality of the sediments, ii) to recognise the areas with the higher contamination risk; and iii) to emphasise the local occurrence of polluting phenomena associated to chromium, nickel, vanadium, cobalt, lead, zinc and copper.

  9. Ecological Effects of Roads on the Plant Diversity of Coastal Wetland in the Yellow River Delta

    PubMed Central

    Li, Yunzhao; Du, Siyao; Han, Guangxuan; Qu, Fanzhu; Wang, Guangmei; Fu, Yuqin; Zhan, Chao

    2014-01-01

    The 26 sample sites in 7 study plots adjacent to asphalt road and earth road in coastal wetland in the Yellow River Delta were selected to quantify plant diversity using quadrat sampling method in plant bloom phase of July and August 2012. The indice of βT and Jaccard's coefficient were applied to evaluate the species diversity. The results showed that the plant diversities and alien plants were high in the range of 0–20 m to the road verge. There were more exotics and halophytes in plots of asphalt roadside than that of earth roadside. However, proportion of halophytes in habitats of asphalt roadsides was lower than that of earth roadside. By comparing β-diversity, there were more common species in the asphalt roadsides than that in the earth roadsides. The similarity of plant communities in studied plots of asphalt roadsides and earth roadsides increased with increasing the distance to road verge. The effect range of roads for plant diversity in study region was about 20 m to road verge. Our results indicate that the construction and maintenance of roads in wetland could increase the plant species diversities of communities and risk of alien species invasion. PMID:25147872

  10. Extreme floods in the Mekong River Delta under climate change: combined impacts of upstream hydrological changes and sea level rise

    NASA Astrophysics Data System (ADS)

    Hoang, Long; Nguyen Viet, Dung; Kummu, Matti; Lauri, Hannu; Koponen, Jorma; van Vliet, Michelle T. H.; Supit, Iwan; Leemans, Rik; Kabat, Pavel; Ludwig, Fulco

    2016-04-01

    Extreme floods cause huge damages to human lives and infrastructure, and hamper socio-economic development in the Mekong River Delta in Vietnam. Induced by climate change, upstream hydrological changes and sea level rise are expected to further exacerbate future flood hazard and thereby posing critical challenges for securing safety and sustainability. This paper provides a probabilistic quantification of future flood hazard for the Mekong Delta, focusing on extreme events under climate change. We developed a model chain to simulate separate and combined impacts of two drivers, namely upstream hydrological changes and sea level rise on flood magnitude and frequency. Simulation results show that upstream changes and sea level rise substantially increase flood hazard throughout the whole Mekong Delta. Due to differences in their nature, two drivers show different features in their impacts on floods. Impacts of upstream changes are more dominant in floodplains in the upper delta, causing an increase of up to +0.80 m in flood depth. Sea level rise introduces flood hazard to currently safe areas in the middle and coastal delta zones. A 0.6 m rise in relative sea level causes an increase in flood depth between 0.10 and 0.70 m, depending on location by 2050s. Upstream hydrological changes and sea level rise tend to intensify each other's impacts on floods, resulting in stronger combined impacts than linearly summed impacts of each individual driver. Substantial increase of future flood hazard strongly requires better flood protection and more flood resilient development for the Mekong Delta. Findings from this study can be used as quantified physical boundary conditions to develop flood management strategies and strategic delta management plans.

  11. A Tale of Two Deltas: Contrasting Perspectives on the State of Natural and Human-modified Regions of the Ganges-Brahmaputra River Delta (Invited)

    NASA Astrophysics Data System (ADS)

    Goodbred, S. L.; Wallace Auerbach, L.; Wilson, C.; Gilligan, J. M.; Roy, K.; Ahmed, K.; Steckler, M. S.; Seeber, L.; Akhter, S. H.; Hossain, S.

    2013-12-01

    Effective risk analysis and the management of complex coastal systems require that the scale of interest be well defined. Here we present recent research from the Ganges-Brahmaputra river delta (GBD) that highlights different, if not divergent, perspectives on the current status of this system and its potential response to future environmental change. The contrasts emerge from viewing the GBD at different temporal and spatial scales, raising the question of how scientists, stakeholders, and decision makers might most effectively develop a shared understanding of large, at-risk delta systems. Among the world's deltas, the GBD is often cited as being highly vulnerable to future sea-level rise and environmental change, owing to its vast low-lying landscape and large human population. Taking a broad perspective, however, it is not coincident that the GBD, the world's largest delta system, is fed by immense water and sediment discharge from the Asian monsoon and Himalayan orogen - simply, the size of the GBD reflects the robust processes that have constructed and maintained it. At the regional scale, the deltaplain itself is interconnected by a labyrinth of fluvial and tidal channels that effectively convey sediment to most areas of the landscape, through overbank flooding, distributaries, and tidal transport. Together, the sediment supply, water discharge, and dense channel network bless the GBD with potential basinwide accretion rates >5 mm/yr. More locally, modern sedimentation rates >10 mm/yr are observed in many areas of the tidal delta plain, which are sufficient to maintain land-surface elevations under a variety of sea-level rise scenarios, or at least to mitigate whatever effects do occur. The long-term stratigraphic record of the GBD also reflects a system in dynamic equilibrium, with major landforms persisting through changes in sea level, sediment loading, river avulsion, and delta lobe switching - together providing an encouraging outlook in the face of

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

    NASA Astrophysics Data System (ADS)

    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

  13. Determining the Palaeodrainage of the Nile River from a Provenance Study of the Nile Delta Cone Sediments

    NASA Astrophysics Data System (ADS)

    Fielding, L.; Najman, Y.; Millar, I.; Butterworth, P.; Garzanti, E.; Kneller, B. C.

    2014-12-01

    This study documents the palaeodrainage history of the Nile River, in particular the time of its transition from a small locally sourced drainage network to the initiation of an extensive catchment. Today, the Nile drains as far south as Lake Victoria, with the White Nile draining largely cratonic rocks of Archean to Proterozoic age and the Blue Nile draining Cenozoic Ethiopian Continental Flood Basalts and Neoproterozoic basement. However, the timing of catchment expansion to the river's current extent is highly debated. Two end member models are: A) The Blue Nile did not connect with the lower Nile until the Late Messinian, and the White Nile not until 0.5 Ma. In this model, the pre-Messinian Nile delta sediments are locally derived from the Red Sea Hills (RSH) (Issawi and McCauley 1992). B) The Blue Nile has been connected to the lower Nile since the Oligocene (Burke and Wells 1989). Onshore fieldwork characterised each possible source area (Ethiopian flood basalts, Archean craton, and Neoproterozoic basement and Phanerozoic cover sequences of the RSH) using petrography, geochemistry and isotope studies. Tertiary-aged Nile delta sediments provide a unique archive of the river's palaeodrainage history, which were analysed from conventional core from exploration and appraisal wells in order to identify the occurrence (if any) of these sources in the delta geological record. Heavy mineral, petrographic, U/Pb rutile and Lu/Hf zircon analyses indicate Blue Nile and/or RSH input to the Nile delta since at least the Oligocene with very little input from the White Nile. Sr and Nd whole-rock analyses of mud samples allow discrimination between the Blue Nile and RSH sources and may, subject to further analyses, confirm Blue Nile input to the delta since the Oligocene. U-Pb zircon analyses reveal the presence of 20-30 Ma zircons in both the modern river sediments from the Ethiopian Highlands and the Nile Delta core from the early Miocene to present day indicating a

  14. Determining the palaeodrainage of the Nile river from a provenance study of the Nile delta cone sediments

    NASA Astrophysics Data System (ADS)

    Fielding, Laura; Najman, Yani; Millar, Ian; Butterworth, Peter; Garzanti, Eduardo; Kneller, Ben

    2014-05-01

    This study documents the palaeodrainage history of the Nile River, in particular the time of its transition from a small locally sourced drainage network to the initiation of an extensive catchment. Today, the Nile drains as far south as Lake Victoria, with the White Nile draining largely cratonic rocks of Archean to Proterozoic age and the Blue Nile draining Cenozoic Ethiopian Continental Flood Basalts and Neoproterozoic basement. However, the timing of catchment expansion to the river's current extent is highly debated. Two end member models are: A) The Blue Nile did not connect with the lower Nile until the Late Messinian, and the White Nile not until 0.5 Ma. In this model, the pre-Messinian Nile delta sediments are locally derived from the Red Sea Hills (RSH) (Issawi and McCauley 1992). B) The Blue Nile has been connected to the lower Nile since the Oligocene (Burke and Wells 1989). Onshore fieldwork characterised each possible source area (Ethiopian flood basalts, Archean craton, and Neoproterozoic basement and Phanerozoic cover sequences of the RSH) using petrography, geochemistry and isotope studies. Tertiary-aged Nile delta sediments provide a unique archive of the river's palaeodrainage history, which were analysed from conventional core from exploration and appraisal wells in order to identify the occurrence (if any) of these sources in the delta geological record. Heavy mineral, petrographic, U/Pb rutile and Lu/Hf zircon analyses indicate Blue Nile and/or RSH input to the Nile delta since at least the Oligocene with very little input from the White Nile. Sr and Nd whole-rock analyses of mud samples allow discrimination between the Blue Nile and RSH sources and may, subject to further analyses, confirm Blue Nile input to the delta since the Oligocene. U-Pb zircon analyses reveal the presence of 20-30 Ma zircons in both the modern river sediments from the Ethiopian Highlands and the Nile Delta core from the early Miocene to present day indicating a

  15. Initiation of the Mekong River delta at 8 ka: evidence from the sedimentary succession in the Cambodian lowland

    NASA Astrophysics Data System (ADS)

    Tamura, Toru; Saito, Yoshiki; Sieng, Sotham; Ben, Bunnarin; Kong, Meng; Sim, Im; Choup, Sokuntheara; Akiba, Fumio

    2009-02-01

    Modern deltas are understood to have initiated around 7.5-9 ka in response to the deceleration of sea-level rise. This episode of delta initiation is closely related to the last deglacial meltwater events and eustatic sea-level rises. The initial stage of the Mekong River delta, one of the world's largest deltas, is well recorded in Cambodian lowland sediments. This paper integrates analyses of sedimentary facies, diatom assemblages, and radiocarbon dates for three drill cores from the lowland to demonstrate Holocene sedimentary evolution in relation to sea-level changes. The cores are characterized by a tripartite succession: (1) aggrading flood plain to natural levee and tidal-fluvial channel during the postglacial sea-level rise (10-8.4 ka); (2) aggrading to prograding tidal flats and mangrove forests around and after the maximum flooding of the sea (8.4-6.3 ka); and (3) a prograding fluvial system on the delta plain (6.3 ka to the present). The maximum flooding of the sea occurred at 8.0 ± 0.1 ka, 2000 years before the mid-Holocene sea-level highstand, and tidal flats penetrated up to 20-50 km southeast of Phnom Penh after a period of abrupt ˜5 m sea-level rise at 8.5-8.4 ka. The delta progradation then initiated as a result of the sea-level stillstand at around 8-7.5 ka. Another rapid sea-level rise at 7.5-7 ka allowed thick mangrove peat to be widely deposited in the Cambodian lowland, and the peat accumulation endured until 6.3 ka. Since 6.3 ka, a fluvial system has characterized the delta plain, and the fluvial sediment discharge has contributed to rapid delta progradation. The uppermost part of the sedimentary succession, composed of flood plain to natural-levee sediments, reveals a sudden increase in sediment accumulation over the past 600-1000 years. This increase might reflect an increase in the sediment yield due to human activities in the upper to middle reaches of the Mekong, as with other Asian rivers.

  16. Survival and migration route probabilities of juvenile Chinook salmon in the Sacramento-San Joaquin River Delta during the winter of 2009-10

    USGS Publications Warehouse

    Perry, Russell W.; Romine, Jason G.; Brewer, Scott J.; LaCivita, Peter E.; Brostoff, William N.; Chapman, Eric D.

    2012-01-01

    Juvenile Chinook salmon (Oncorhynchus tshawytscha) emigrating from natal tributaries of the Sacramento River may use a number of migration routes to negotiate the Sacramento-San Joaquin River Delta (hereafter, "the Delta"), each of which may influence their probability of surviving. We applied a mark-recapture model to data from acoustically tagged juvenile late-fall Chinook salmon that migrated through the Delta during the winter of 2009-10 (hereafter, 2010). This report presents findings from our fourth year of research. We estimated route-specific survival for four release groups: two release groups that migrated through the Delta in December 2009 and January 2010, and two release groups that migrated during February 2010. Population-level survival through the Delta (SDelta) ranged from 0.374 (SE = 0.040) to 0.524 (SE = 0.034) among releases. Although river flows for the February release groups were substantially higher (20,000-40,000 ft3/s at Freeport) than for the December release groups (about 10,000 ft3/s), SDelta did not differ considerably between release groups. Among migration routes, fish migrating through the Sacramento River exhibited the highest survival, and fish entering the interior Delta exhibited the lowest survival. Fish entering Sutter and Steamboat Sloughs had lower survival than fish entering the Sacramento River during December, but similar survival during February. These patterns were consistent among release groups, and strikingly similar to patterns observed in previous years. Migration routing varied among release groups partly because of differences in river discharge between releases. For the two December release groups, 26.5 and 28.9 percent of fish entered the interior Delta; for the two February release groups, 10.4 and 17.9 percent of fish entered the interior Delta. Differences in routing probabilities between December and February are partly related to the inverse relationship between flow and the fraction of discharge entering

  17. Bacterial Investigation of Ammonium-rich Sediment in the Pearl River Delta, China

    NASA Astrophysics Data System (ADS)

    Liu, K.; Chunbo, H.; Jiao, J. J.; Jidong, G.

    2011-12-01

    High ammonium loading of groundwater is a major concern because of the potential toxicity to ecosystem and human health. As one of the most complex large-scale delta systems in China, Pearl River Delta (PRD) was reported to have the highest ammonium concentration for natural groundwater ever reported globally. In this research, borehole SD14 was drilled through the aquitard into the basal aquifer in the PRD. 16S rRNA gene library construction and Denaturing Gradient Gel Electrophoresis (DGGE) analysis were conducted to reveal bacterial community variation of different geology strata. A total of 161 clones from three 16S rRNA libraries were sequenced and clustered into 55 distinct operational taxonomic units (OTU) at 3% cutoff. The phylogenetic analysis indicated that the predominant bacterial phylum was Proteobacteria (50.9%), followed by Chloroflexi (16.8%), Acidobacteria (4.38%) and Firmicutes (3.73%). In the sediment samples from SD14 at the depths of 6.9m, 22.5m and 37.4m, Proteobacteria made up 60.3%, 42.0% and 35.3% of the communities respectively, showing a declining ratio with the depth. Most of the bacteria in all the samples were previously discovered in marine environments, indicating that SD14 used to be in a marine sedimentary environment. Bacteria associated with iron oxidation and nitrogen fixing were found in the sample at 6.9 m, while in the other two samples there existed bacteria which were associated with methane cycling, sulfate reducing and denitrifying. The DGGE results showed that microbial community structures varied significantly with the increase of depth, and that Delftia acidovorans, a species of Proteobacteria which was able to reduce nitrate to nitrite, was the predominant species in samples at 22.5 and 37.4 m, suggesting ammonium as a control factor shaping the bacterial community. The results of this research provided important information of the bacteria in the PRD sediments. High bacterial diversity was observed in samples, and

  18. Assessing subaqueous mudslide hazard on the Mississippi River delta front, Part 2: Insights revealed through high-resolution geophysical surveying

    NASA Astrophysics Data System (ADS)

    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 (<0.5°) due to (1) high rates of fine-grained sedimentation and associated underconsolidation, (2) excess sediment pore pressure attributed to in-situ biogenic 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

  19. Earthshots: Satellite images of environmental change – Inland Delta of the Niger River, Mali

    USGS Publications Warehouse

    Adamson, Thomas

    2016-01-01

    This delta floods seasonally from September to December, as rainfall from the river’s headwaters in the Guinea Highlands reaches the delta’s vast flat floodplain. The southern part of the delta is low-lying floodplain with expanses of wetland grasses and reeds. The northern part has sand ridges that emerge from the water during the flood season. The seasonal flooding supports fisheries, pasture, and rice farming. Over 1 million people depend on resources in the delta.

  20. Understanding environmental controls on the hydrodynamics of a river delta's interdistributary islands

    NASA Astrophysics Data System (ADS)

    Hiatt, M. R.; Wagner, R. W.; Geleynse, N.; Passalacqua, P.

    2013-12-01

    River deltas are dynamic systems of environmental, ecological, and societal importance. In coastal Louisiana, wetland loss and increased nutrient loadings are altering the eco-geomorphic equilibrium, raising awareness to the environmental concerns associated with climate and anthropogenic change. Over the last 100 years, nearly 5000 km2 of wetlands in coastal Louisiana have been submerged due to a variety of environmental and anthropogenic forces [Day Jr. et al., 2007]. Denitrification in coastal Louisiana wetlands has been shown to reduce the export of nitrogen to receiving waters, which limits the risks of hypoxia and related environmental issues [Rivera-Monroy et al., 2010]. Specifically, inundated interdistributary islands are hypothesized to be zones of potential significant nitrogen cycling. The goal of this research is to understand the hydrodynamics of the inundated interdistributary islands at Wax Lake Delta (WLD) in Louisiana, USA. Previous work has shown that a significant portion of the water at WLD is exchanged between the channels and the islands [Buttles et al., 2006; Hiatt et al., 2012]. We employ field measurements to monitor the propagation of fluorescent dye through the island and to estimate the hydraulic residence time (HRT). We compare the results to modeling output using Delft3D. The field and modeling results are supported by ADCP measurements made during the field study. Water depth, temperature, and salinity data were also collected during the tracer study. Both dye propagation patterns and measured velocities point to different hydrodynamic behavior depending on environmental conditions (tides and wind). For example, dispersion of dye is increased during flood tide and is minimized during ebb tide. HRTs are on the order of hours under the measured environmental conditions, whereas HRTs associated with significant dentrification have been shown to be on a monthly timescale [Branhoff, 2012]. Using principal components analysis, we quantify

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

    SciTech Connect

    Sobocinski, Kathryn; Johnson, Gary; Sather, Nichole

    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) Determine fish

  2. Soil controls on land-atmosphere methane fluxes from an arctic floodplain of the Lena River Delta, Siberia

    NASA Astrophysics Data System (ADS)

    Runkle, Benjamin; Sabrekov, Alexander; Glagolev, Mikail; Kutzbach, Lars

    2014-05-01

    Accurately quantifying methane emissions from permafrost tundra landscapes into the atmosphere is a major concern of the global climate modeling community. A better, data-driven understanding of the drivers of soil-atmosphere CH4 fluxes could help constrain the global methane balance, offer predictions in response to global climate change, and advance understanding of these regions' soil biogeochemistry and landscape ecology. Previous research at our Lena River Delta research site (72° N, 126° E) has found relatively low methane emissions (~18-30 mg m2 d1) in the polygonal tundra of the delta's Holocene river terrace (Sachs et al., 2008; Wille et al., 2008). In fall 2013 we compare methane emissions from this landscape type to the adjacent active river floodplain, a sandy, Equisetum - Salix -Alopecurus alpinus community ecosystem. This landscape has backswamp regions with higher organic matter accumulation though is generally dominated by soils with high sand contents, low organic matter content, and lower water tables than the Holocene terrace (Boike et al., 2013). The wet parts of a similar landscape unit in the Indigirka lowlands (71° N, 147° E) have been demonstrated to have greater methane emissions which were in part attributed to the annual deposition of nutrients via flooding, increased primary productivity and associated root exudates, and higher soil temperatures. The results presented in this study compare methane fluxes derived from the closed chamber technique from the two landscape units. In addition to descriptions of the inundation height and vegetation cover, we examine soil chemical and physical characteristics to test how these factors help control CH4 fluxes. We find, for example, relatively high concentrations of dissolved organic carbon at sites with relatively high CH4 production. As the modern floodplain landscape type covers 40% of the soil-covered area of the Lena River Delta and is analogous to similar regions across the Arctic

  3. Relation between oceanic conditions in the South China Sea and water levels within and along the Vietnamese Mekong River Delta

    NASA Astrophysics Data System (ADS)

    Uehara, K.; Tanaka, A.; Saito, Y.; Tamura, T.; Nguyen, V. L.; Ta, T. K.

    2013-12-01

    Seasonal water level change within and around the Vietnamese Mekong River Delta (MRD) has been analyzed to understand the impact of climate change in the South China Sea on river flooding within the MRD. It was found that the sea level variability along the deltaic coast has high coherence with the strength of offshore oceanic currents which seasonally reverse their direction under the SE Asian monsoon climate, indicating that the coastal sea level is linked with offshore currents through a geostrophic relation. It was also suggested that the temporal pattern of water levels in the middle reaches of the MRD, 80-100km apart from the river mouth, was influenced not only by upstream information but also by the downstream sea level change. These results indicates that the climatic change in the oceanic current field may influence the occurrence of flooding within the MRD especially during the NE monsoon season when the sea level is high.

  4. Organic Carbon and Nitrogen Storages of Soils Overlying Yedoma Deposits in the Lena River Delta

    NASA Astrophysics Data System (ADS)

    Zubrzycki, Sebastian; Kutzbach, Lars; Desiatkin, Aleksei; Pfeiffer, Eva-Maria

    2016-04-01

    The Lena River Delta (LRD) is located in northeast Siberia and extends over a soil covered area of around 21,500 km2. LRD likely stores more than half of the entire soil organic carbon (SOC) mass stored in deltas affected by permafrost. LRD consists of several geomorphic units. Recent studies showed that the spatially dominating Holocene units of the LRD (61 % of the area) store around 240 Tg of SOC and 12 Tg of nitrogen (N) within the first meter of ground. These units are a river terrace dominated by wet sedge polygons and the active floodplains. About 50 % of these reported storages are located in the perennially frozen ground below 50 cm depth and are excluded from intense biogeochemical exchange with the atmosphere today. However, these storages are likely to be mineralised in near future due to the projected temperature increases in this region. A substantial part of the LRD (1,712 km2) belongs to the so-called Yedoma Region, which formed during the Late Pleistocene. This oldest unit of the LRD is characterised by extensive plains incised by thermo-erosional valleys and large thermokarst depressions. Such depressions are called Alases and cover around 20 % of the area. Yedoma deposits in the LDR are known to store high amounts of SOC. However, within the LRD no detailed spatial studies on SOC and N in the soils overlying Yedoma and thermokarst depressions were carried out so far. We present here our "investigation in progress" on soils in these landscape units of the LRD. Our first estimates, based on 69 pedons sampled in 2008, show that the mean SOC stocks for the upper 30 cm of soils on both units were estimated at 13.0 kg m2 ± 4.8 kg m2 on the Yedoma surfaces and at 13.1 kg m2 ± 3.8 kg m2 in the Alases. The stocks of N were estimated at 0.69 kg m2 ± 0.25 kg m2and at 0.70 kg m2 ± 0.18 kg m2 on the Yedoma surfaces and in the Alases, respectively. The estimated SOC and N pools for the depth of 30 cm within the investigated part of the LRD add to 20.9 Tg

  5. An ozone episode in the Pearl River Delta: Field observation and model simulation

    NASA Astrophysics Data System (ADS)

    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

  6. Discharge diversion in the Patía River delta, the Colombian Pacific: Geomorphic and ecological consequences for mangrove ecosystems

    NASA Astrophysics Data System (ADS)

    Restrepo, Juan D.; Cantera, Jaime R.

    2013-10-01

    In the Patía River delta, the best-developed delta on the western margin of South America, a major water diversion started in 1972. The diversion of the Patía flow to the Sanquianga River, the latter a small stream draining internal lakes from the Pacific lowlands, shifted the active delta plain from the south to the north and changed the northern estuarine system into an active delta plain. The Sanquianga Mangrove National Park, a mangrove reserve measuring 800 km2, lies in this former estuary, where major hydrologic and sedimentation changes are occurring. Overall, major environmental consequences of this discharge diversion in terms of geomorphic changes along distributary channels and ecological impacts on mangrove ecosystems are evidenced by: (1) distributary channel accretion by operating processes such as sedimentation, overbank flow, increasing width of levees, sedimentation in crevasses, interdistributary channel fill, and colonization of pioneer mangrove; (2) freshening conditions in the Sanquianga distributary channel, a hydrologic change that has shifted the upper estuarine region (salinity <1%) downstream; (3) downstream advance of freshwater vegetation, which is invading channel banks in the lower and mixing estuarine zones; (4) die-off of approximately 5200 ha of mangrove near the delta apex at Bocas de Satinga, where the highest sediment accumulation rates occur; and (5) recurrent periods of mangrove defoliation due to a worm plague. Further analyses indicate strong mangrove erosion along transgressive barrier islands on the former delta plain. Here tectonic-induced subsidence, relative sea-level rise, and sediment starving conditions due to the channel diversion, are the main causes of the observed retreating conditions of mangrove communities. Our data also indicate that the Patía River has the highest sediment load (27 × 106 t yr-1) and basin-wide sediment yield (1500 t km-2 yr-1) on the west coast of South America. Erosion rates from the Pat

  7. Dissolved and Colloidal Trace Elements in the Mississippi River Delta Outflow after Hurricanes Katrina and Rita

    NASA Astrophysics Data System (ADS)

    Shim, M.; Swarzenski, P. W.; Shiller, A. M.

    2010-12-01

    The Mississippi River (MR) plays an important role as a major fluvial source of dissolved and particulate materials for the Gulf of Mexico (GOM). This region is periodically disturbed by tropical weather systems including major hurricanes. Such storms have the potential to stir up the normally stratified water column of the Louisiana Shelf and thus can serve as a mechanism for the abrupt termination of seasonal bottom water hypoxia. Additionally, strong tropical systems can cause the resuspension of shelf bottom sediments which could result in the injection of trace elements into the water column. In the summer of 2005, two major hurricanes, Katrina and Rita, passed over the Louisiana Shelf within a month of each other. Three weeks after Rita, we participated in a survey of the waters of the Mississippi River delta outflow, examining the distributions of trace elements (including Ba, Co, Cr, Cs, Cu, Fe, Mn, Ni, Re, U, V, and Zn) in a comparison with previous results in this area. We indeed observed that there was limited stratification on the shelf and that bottom waters were no longer hypoxic. This resulted, for instance, in bottom water dissolved Mn being lower than is typically observed during hypoxia, but with concentrations still compatible with Mn-O2 trends previously reported. Interestingly, for no element were we able to identify an obvious effect of sediment resuspension on its distribution. In general, elemental distributions were compatible with previous observations in the Mississippi outflow system. Co and Re, which have not been reported for this system previously, showed behavior consistent with other systems: input for Co likely from desorption and conservative mixing for Re. For Cs, an element for which there is little information regarding its estuarine behavior, conservative mixing was also observed. Our filtration method, which allowed us to distinguish the dissolved (<0.02 µm) from colloidal (0.02 - 0.45 µm) phase, revealed significant

  8. Black carbon measurements in the Pearl River Delta region of China

    NASA Astrophysics Data System (ADS)

    Huang, X.; Gao, R.; Schwarz, J. P.; Ling-Yan, H.; Fahey, D. W.; Laurel A, W.; Zeng, L.

    2009-12-01

    The Pearl River Delta (PRD) region in southeastern China is one of the most polluted industrial/metropolitan areas in the world. The 3C-STAR campaign (Synthesized Prevention Techniques for Air Pollution Complex and Integrated Demonstration in Key City-Cluster Region), carried out in October-November, 2008, was aimed at improving the understanding and quantification of air pollution in the region, while developing technical capacity for regional air quality monitoring and modeling. We report single-particle soot photometer (SP2) measurements and analyses of refractory black carbon (rBC) at Kaiping, a rural site downwind of the major pollution sources in the PRD area. The rBC mass loadings varied between 0.5 and 10 µg-rBC kg-air-1, and averaged 2.8 µg-rBC kg-air-1. These values are roughly an order of magnitude higher than those measured in the Houston, Texas, a major US metropolitan area. The rBC mass distributions show a primary lognormal peak with a median mass diameter of 0.22 µm volume-equivalent diameter (VED), which is similar to those observed in Houston and other regions with the SP2 instrument. A second mode with a mass median diameter of 0.69 µm VED, has not been observed before. Coatings are found on over 50% of rBC particles, suggesting that they are aged and/or of biomass-burning origin. The high rBC loadings cause significant heating of the atmosphere due to direct solar absorption. A diurnal heating rate of over 0.5 K day-1. is estimated for the average of entire dataset with a maximum heating rate near 3 K day-1.

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

    SciTech Connect

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

    2014-05-15

    China announced the Chinese National Ambient Air Quality standards (CH-NAAQS) on Feb. 29th, 2012, and PM2.5 is for the very first time included in the standards as a criteria pollutant. In order to probe into PM2.5 pollution over Yangtze River Delta, which is one of the major urban clusters hosting more than 80 million people in China, 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. Both simulation and observation demonstrated that, inorganic aerosols have substantial contributions 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. We also found that in winter NO3- was even increased 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 (SO42-), 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 VOC sensitive 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.

  10. [Influence of Burning Fireworks on Air Quality During the Spring Festival in the Pearl River Delta].

    PubMed

    Zhao, Wei; Fan, Shao-jia; Xie, Wen-zhang; Sun, Jia-ren

    2015-12-01

    Based on data from the air quality monitoring stations in the Pearl River Delta during the 2015 Spring Festival, the regional air quality was investigated and the impact of burning fireworks on urban air quality was assessed. The results showed that: Zhaoqing was the worst polluted city in PM₁₀, PM₂.₅, SO₂ and CO in terms of concentrations in the region during the period, Huizhou was the worst polluted city in O₃ and Guangzhou was the most polluted city in NO₂ at the same time. Compared to the data of last year, the SO₂, NO₂, CO, PM₁₀ and PM₂.₅ concentrations had decreased significantly, but the O₃ concentration had increased during the Spring Festival. Burning fireworks during the Spring Festival were mainly concentrated in the suburbs. The concentrated discharge of fireworks made the SO₂, PM₁₀ and PM₂.₅ concentrations increased significantly in the New Year's Eve night, even multiplied, but had no significant effect on CO, O₃ and NO₂. The rapid decline in PM₂.₅/PM₁₀ proportion was caused by the discharge of fireworks, and the ratio of PM₂.₅/PM₁₀ reached the minimum when concentration of particles reached the peak. By assessing, the maximum contribution of hourly concentration from burning fireworks in each city was between 16 µg · m⁻³ and 65 µg · m⁻³ for PM₂.₅, between 28 µg · m⁻³ and 138 µg · m⁻³ for PM₁₀ and between 9 µg · m⁻³ and 43 µg · m⁻³ for SO₂.

  11. Arsenic contamination in the freshwater fish ponds of Pearl River Delta: bioaccumulation and health risk assessment.

    PubMed

    Cheng, Zhang; Chen, Kun-Ci; Li, Kai-Bin; Nie, Xiang-Ping; Wu, Sheng Chun; Wong, Chris Kong-Chu; Wong, Ming-Hung

    2013-07-01

    This study investigated the extent of arsenic (As) contamination in five common species of freshwater fish (northern snakehead [Channa argus], mandrarin fish [Siniperca chuatsi], largemouth bass [Lepomis macrochirous], bighead carp [Aristichthys nobilis] and grass carp [Ctenopharyngodon idellus]) and their associated fish pond sediments collected from 18 freshwater fish ponds around the Pearl River Delta (PRD). The total As concentrations detected in fish muscle and sediment in freshwater ponds around the PRD were 0.05-3.01 mg kg(-1) wet weight (w. wt) and 8.41-22.76 mg kg(-1) dry weight (d. wt), respectively. In addition, the As content was positively correlated (p < 0.05) to total organic carbon (TOC) contents in sediments. Biota sediment accumulation factor (BSAF) showed that omnivorous fish and zooplankton accumulated higher concentrations of heavy metals from the sediment than carnivorous fish. In addition, feeding habits of fish also influence As accumulation in different fish species. In this study, two typical food chains of the aquaculture ponds were selected for investigation: (1) omnivorous food chain (zooplankton, grass carp and bighead carp) and (2) predatory food chain (zooplankton, mud carp and mandarin fish). Significant linear relationships were obtained between log As and δ (15)N. The slope of the regression (-0.066 and -0.078) of the log transformed As concentrations and δ (15)N values, as biomagnifications power, indicated there was no magnification or diminution of As from lower trophic levels (zooplankton) to fish in the aquaculture ponds. Consumption of largemouth bass, northern snakehead and bighead carp might impose health risks of Hong Kong residents consuming these fish to the local population, due to the fact that its cancer risk (CR) value exceeded the upper limit of the acceptable risk levels (10(-4)) stipulated by the USEPA.

  12. Arsenic contamination in the freshwater fish ponds of Pearl River Delta: bioaccumulation and health risk assessment.

    PubMed

    Cheng, Zhang; Chen, Kun-Ci; Li, Kai-Bin; Nie, Xiang-Ping; Wu, Sheng Chun; Wong, Chris Kong-Chu; Wong, Ming-Hung

    2013-07-01

    This study investigated the extent of arsenic (As) contamination in five common species of freshwater fish (northern snakehead [Channa argus], mandrarin fish [Siniperca chuatsi], largemouth bass [Lepomis macrochirous], bighead carp [Aristichthys nobilis] and grass carp [Ctenopharyngodon idellus]) and their associated fish pond sediments collected from 18 freshwater fish ponds around the Pearl River Delta (PRD). The total As concentrations detected in fish muscle and sediment in freshwater ponds around the PRD were 0.05-3.01 mg kg(-1) wet weight (w. wt) and 8.41-22.76 mg kg(-1) dry weight (d. wt), respectively. In addition, the As content was positively correlated (p < 0.05) to total organic carbon (TOC) contents in sediments. Biota sediment accumulation factor (BSAF) showed that omnivorous fish and zooplankton accumulated higher concentrations of heavy metals from the sediment than carnivorous fish. In addition, feeding habits of fish also influence As accumulation in different fish species. In this study, two typical food chains of the aquaculture ponds were selected for investigation: (1) omnivorous food chain (zooplankton, grass carp and bighead carp) and (2) predatory food chain (zooplankton, mud carp and mandarin fish). Significant linear relationships were obtained between log As and δ (15)N. The slope of the regression (-0.066 and -0.078) of the log transformed As concentrations and δ (15)N values, as biomagnifications power, indicated there was no magnification or diminution of As from lower trophic levels (zooplankton) to fish in the aquaculture ponds. Consumption of largemouth bass, northern snakehead and bighead carp might impose health risks of Hong Kong residents consuming these fish to the local population, due to the fact that its cancer risk (CR) value exceeded the upper limit of the acceptable risk levels (10(-4)) stipulated by the USEPA. PMID:23247527

  13. Halocarbons in the atmosphere of the industrial-related Pearl River Delta region of China

    NASA Astrophysics Data System (ADS)

    Chan, L. Y.; Chu, K. W.

    2007-02-01

    In a study conducted in 2000, 19 halocarbons from 78 canister air samples were measured in five industrial cities in the Pearl River Delta (PRD), one of the fastest growing industrial regions in China. Preliminary year 2000 halocarbon levels have been derived using available data and information. Comparisons have been made between the data obtained in this study and the corresponding estimated global/tropical surface mixing ratios obtained from the literature. With the exception of CFC-114 and halon-2402, the halocarbons had significant enhancements, presumably due to their recent increased production and extensive industrial uses. In contrast to the small enhancements (<7%) for two chlorofluorocarbons (CFC-11 and CFC-12), large enhancements (>30%) for three HCFC replacements (HCFC-22, -141b, -142b) were observed. In general, HCFCs have virtually replaced CFCs, except for some localized usage. The median of HFC-134a also had a 36% enhancement; however, 23% of the samples were near or at the global background level. These contradictory results could not give a clear situation of uses of this new chemical in the region. Our data also indicate that halocarbon-based cleaning solvents, including CFC-113, methyl chloroform, trichloroethene and tetrachloroethene, were still frequently used in PRD industries. High mixing ratios of these halogenated solvents were frequently measured in Dongguan, a city with light industry. Higher atmospheric levels of the three methyl halides (-Cl, -Br, and -I) were found in a coastal city, Jiangmen. These may be contributed to by industrial emissions and coastal terrestrial and coastal seawater sources.

  14. Emission patterns and spatiotemporal variations of halocarbons in the Pearl River Delta region, southern China

    NASA Astrophysics Data System (ADS)

    Zhang, Y. L.; Guo, H.; Wang, X. M.; Simpson, I. J.; Barletta, B.; Blake, D. R.; Meinardi, S.; Rowland, F. S.; Cheng, H. R.; Saunders, S. M.; Lam, S. H. M.

    2010-08-01

    On 8 selected days between 25 October and 1 December 2007, 198 whole air samples were simultaneously collected at two sites in the greater Pearl River Delta (PRD), namely, Wan Qing Sha (WQS) in inland PRD and Tung Chung (TC) in Hong Kong, for the evaluation of halocarbons including chlorofluorocarbons (CFCs), hydrochlorofluorocarbons (HCFCs) and other chlorinated compounds. The mean mixing ratios of CFC-12, CH3CCl3, CH3Br, C2HCl3, and C2Cl4 at WQS were much higher than those at TC (p < 0.001), while HCFC-22 was higher at TC (p < 0.01). Long-lived species such as CFC-11, CFC-12, and CFC-113 showed similar temporal patterns on most sampling days with small daily variation, whereas the main species used as solvents such as C2HCl3 and C2Cl4 presented large daily variations though with consistent temporal patterns. Source profile analysis revealed that although there was no remarkable change in emission sources between 2001-2002 and 2007, the emissions of CFCs and CCl4 from the production of refrigeration in 2007 were 1.4-2.0 times those in 2001-2002, and the use of HCFC-22 has significantly increased in these years while the use of C2HCl3 and C2Cl4 in the electronics industry showed a remarkable reduction. By comparing the halocarbon data collected in this study with those observed by other research teams in recent years, we found that the levels of CFCs have declined since 2001, while their substitute HCFC-22 has increased in emissions in recent years, especially in Hong Kong. The annual trends are consistent with the implementation of the Montreal Protocol. The results obtained in this study provide useful information to local government on effective control of halocarbon emissions in this region.

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

    PubMed

    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. PMID:22995707

  16. Measurement and Analysis of a Multiday Photochemical Smog Episode in the Pearl River Delta of China.

    NASA Astrophysics Data System (ADS)

    Wang, Tao; Kwok, Joey Y. H.

    2003-03-01

    Recent measurements of a photochemical episode in September of 2001 in the Pearl River delta (PRD) were analyzed to gain insight into the meteorological and chemical processes affecting ozone (O3) concentrations in the subtropical southern China coast. High concentrations (>120 ppbv) of O3 were observed at a rural coastal site in western Hong Kong for six consecutive days, with maximum 1-h O3 concentration reaching 191 ppbv and visibility decreasing to 1.8 km. Comparison with O3 data obtained from six other sites in the region indicated the regional nature of the O3 pollution. Examination of synoptic charts showed that this unusually severe and prolonged pollution episode was induced by a quasi-stationary tropical cyclone in the East China Sea that caused air subsidence and stagnation over the PRD. Weak northerly winds were observed from radiosonde and at a mountaintop site, but surface winds showed a complex pattern owing to land-sea breezes and the topography effects. The measurements of O3, carbon monoxide (CO), sulfur dioxide (SO2), nitric oxide (NO), and total reactive nitrogen (NOy) at the western Hong Kong site were analyzed to show the possible sources and emission characteristics of O3-laden plumes. The daytime high concentrations of O3 and other pollutants were caused by the diffusion/advection of urban plumes under light north-northeast winds; and their reduced concentrations in the late afternoon were due to the stronger sea breezes. The large values of CO/NOy and SO2/NOy on some days implied the contribution of regional emissions to the high O3 in western Hong Kong. The data from the western site were compared with those from an eastern site to illustrate the spatial variability of air pollutants in the coastal environment of the study region.

  17. Observations of relative humidity effects on aerosol light scattering in the Yangtze River Delta of China

    NASA Astrophysics Data System (ADS)

    Zhang, L.; Sun, J. Y.; Shen, X. J.; Zhang, Y. M.; Che, H.; Ma, Q. L.; Zhang, Y. W.; Zhang, X. Y.; Ogren, J. A.

    2015-07-01

    Scattering of solar radiation by aerosol particles is highly dependent on relative humidity (RH) as hygroscopic particles take up water with increasing RH. To achieve a better understanding of the effect of aerosol hygroscopic growth on light scattering properties and radiative forcing, the aerosol scattering coefficients at RH in the range of 40 to ~ 90 % were measured using a humidified nephelometer system in the Yangtze River Delta of China in March 2013. In addition, the aerosol size distribution and chemical composition were measured. During the observation period, the mean and standard deviation (SD) of enhancement factors at RH = 85 % for the scattering coefficient (f(85 %)), backscattering coefficient (fb(85 %)), and hemispheric backscatter fraction (fβ(85 %)) were 1.58 ± 0.12, 1.25 ± 0.07, and 0.79 ± 0.04, respectively, i.e., aerosol scattering coefficient and backscattering coefficient increased by 58 and 25 % as the RH increased from 40 to 85 %. Concurrently, the aerosol hemispheric backscatter fraction decreased by 21 %. The relative amount of organic matter (OM) or inorganics in PM1 was found to be a main factor determining the magnitude of f(RH). The highest values of f(RH) corresponded to the aerosols with a small fraction of OM, and vice versa. The relative amount of NO3- in fine particles was strongly correlated with f(85 %), which suggests that NO3- played a vital role in aerosol hygroscopic growth during this study. The mass fraction of nitrate also had a close relationship to the curvature of the humidograms; higher mass fractions of nitrate were associated with humidograms that had the least curvature. Aerosol hygroscopic growth caused a 47 % increase in the calculated aerosol direct radiative forcing at 85 % RH, compared to the forcing at 40 % RH.

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

    PubMed

    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. PMID:25252793

  19. Importance of NOx control for peak ozone reduction in the Pearl River Delta region

    NASA Astrophysics Data System (ADS)

    Li, Ying; Lau, Alexis K. H.; Fung, Jimmy C. H.; Zheng, Junyu; Liu, Shawchen

    2013-08-01

    As major air pollutants and key precursors of several secondary air pollutants, nitrogen oxide (NOx) emissions are regulated in many countries. However, NOx control increases ozone concentrations when the ozone formation regime is volatile organic compound (VOC) limited. Although many studies have shown that NOx regulation reduces ozone levels over the long term, it is still of concern that NOx regulation increases short-term ozone levels in metropolitan regions, where ozone formation is found to be predominantly VOC-limited. The Pearl River Delta (PRD) in China is such a region. Our modeling sensitivity study shows that while NOx reduction in the PRD region may raise the mean ozone concentration, it can also decrease peak ozone levels. Similar changes are observed in the NOx and ozone data of the PRD regional air quality monitoring network (2006-2012), lending further credence to our results. In the model, this NOx control effect is a result of the complicated spatial and diurnal variations of the ozone formation regime. In most of the PRD region, the formation regime is VOC-limited in the morning and becomes NOx-limited during peak ozone hours. Although some areas are always VOC-limited, their ozone concentrations are relatively low, and the ozone increases caused by NOx reduction generally do not cause higher ozone levels than the region's original ozone maxima. Several control scenarios are simulated to evaluate the effects of various possible control regulations. Our results show that in addition to VOC control, NOx control can be effective for reducing peak ozone concentrations in the PRD region.

  20. Characterization of gaseous pollutants and fine particles at a rural site in the Yangtze River Delta

    NASA Astrophysics Data System (ADS)

    Chai, Fa-He; Gao, Jian; Wang, Shu-Lan; Zhang, Yue-Chong; Mu, Yujing; Mellouki, Abdelwahid

    2010-05-01

    The ambient O3, CO, NO-NO2-NOx*, SO2, NH3 and PM2.5 have been monitored at Chongming Island, a rural site in the Yangtze River Delta in the Shanghai area, from October 2008 to September 2009. In this presentation, we report the measured concentration levels, diurnal/seasonal variation, of the species of interest. An analysis of the pollutant sources is also presented. The average concentrations of O3, CO, SO2, NO, NO2, NOx*, NH3 and PM2.5 are 36.7 ppb, 0.7 ppm, 14.3 ppb, 4.8 ppb, 13.5 ppb, 19.7 ppb, 24.9 ppb, and 54.4 µg/m3, respectively. The concentration levels of the gaseous pollutants are lower than the Grades I of both the Chinese Ambient Air Quality Standards and the primary standard of US National Ambient Air Quality Standards. The diurnal profiles of the primary pollutants (CO, SO2) show peak values before noon. The NO and NOx show the similar profiles as CO in warm season, but have bimodal profiles in winter, suggesting the possibility of influence from transport emission in the season. Most of the primary pollutants have maximum values in winter, indicating the influence of fuel burning source during the heating period. O3 keeps high level in the summer. The surface concentration of O3, Ox (O3+NO2) and NO2 at the site and the satellite observed tropospheric columns O3 and NO2 have similar seasonal pattern. The PM2.5 concentration peaks in summer, which has bad correlation with AOD. The relationship among the primary pollutants indicates a significant influence of transport emission over the region. In autumn, the biomass burning emission also seems to be one of the major sources for the air pollutants.

  1. Distribution of phthalate esters in topsoil: a case study in the Yellow River Delta, China.

    PubMed

    Hongjun, Yang; Wenjun, Xie; Qing, Liu; Jingtao, Liu; Hongwen, Yu; Zhaohua, Lu

    2013-10-01

    The Yellow River Delta (YRD) is a typical agricultural and petrochemical industrial area of China. To assess the current status of phthalate esters (PAEs) of soil residues, soil samples (0∼20 cm) (n = 82) were collected in Bincheng District, at the geographic center of the YRD. PAEs were detected in all topsoil samples analyzed, which indicated that PAEs are ubiquitous environmental contaminants. Concentrations of 11 PAEs are in the range of 0.794∼19.504 μg g(-1), with an average value of 2.975 μg g(-1). It was presented that PAEs pollution in this area was weak and monotonously increasing along the rural-urban gradient. Higher concentrations were observed from roadsides (and/or gutters), densely anthropogenic activities areas (such as the urbanization and industrialization), and agriculture influence district, which mainly originated from construction waste, municipal sewage, agricultural waste and pesticide, discarded plastic effusion and atmospheric depositions. Concentrations of PAEs were weakly positivity correlated with soil organic carbon content and pH, which suggested both of them can affect the distribution of PAEs. The concentration of di (2-ethylhexyl) phthalate and di-n-butyl phthalate dominated in the 11 PAEs, with the average values of 0.735 and 1.915 μg g(-1), respectively, and accounted for 92.1 % of the whole PAEs' concentrations. No significant differences of PAE congeneric profiles were observed between our work and others previously reported, which is consistent with the use of similar commercial PAEs around the world. PMID:23609921

  2. [Study on critical loads of sulfur and nitrogen in the Pearl River Delta].

    PubMed

    Sun, Cheng-Ling; Xie, Shao-Dong

    2014-04-01

    Supported by the geographical information system (ArcGIS), critical loads and exceedances of critical loads of sulfur and nitrogen in the Pearl River Delta (PRD) were calculated using Steady-state Mass Balance method with current deposition data, vegetation data and soil data obtained by field sampling and laboratory analysis. Results showed that the present critical loads of sulfur were high in the eastern PRD and low in the west. Higher critical loads occurred in most of Huizhou, north-central Guangzhou, Dongguan and south Zhongshan. The critical loads of these regions were mostly larger than 15 keq x (hm2 x a)(-1). Regions with lower critical loads included most of Jiangmen, most of Zhaoqing and part of Shenzhen with critical loads less than 2 keq x (hm2 x a)(-1). Critical loads of nitrogen were mainly in the range of 1.0-2.5 keq x (hm2 x a)(-1) while values lower than 1.0 keq x (hm2 x a)(-1) were found in Zhaoqing. According to the results of critical load exceedances, in several regions the sulfur deposition exceeded the critical loads whereas in most regions the nitrogen deposition exceeded the critical loads. With the reduction of particulate concentrations in atmosphere in the future, critical loads of sulfur would decrease and sulfur depositions in most regions would exceed their critical loads. Therefore, the control over nitrogen deposition should be strengthened in the present situation and special attention should be paid to the control of sulfur deposition with the reduction of particulate concentrations in the future.

  3. Soil sail content estimation in the yellow river delta with satellite hyperspectral data

    USGS Publications Warehouse

    Weng, Yongling; Gong, Peng; Zhu, Zhi-Liang

    2008-01-01

    Soil salinization is one of the most common land degradation processes and is a severe environmental hazard. The primary objective of this study is to investigate the potential of predicting salt content in soils with hyperspectral data acquired with EO-1 Hyperion. Both partial least-squares regression (PLSR) and conventional multiple linear regression (MLR), such as stepwise regression (SWR), were tested as the prediction model. PLSR is commonly used to overcome the problem caused by high-dimensional and correlated predictors. Chemical analysis of 95 samples collected from the top layer of soils in the Yellow River delta area shows that salt content was high on average, and the dominant chemicals in the saline soil were NaCl and MgCl2. Multivariate models were established between soil contents and hyperspectral data. Our results indicate that the PLSR technique with laboratory spectral data has a strong prediction capacity. Spectral bands at 1487-1527, 1971-1991, 2032-2092, and 2163-2355 nm possessed large absolute values of regression coefficients, with the largest coefficient at 2203 nm. We obtained a root mean squared error (RMSE) for calibration (with 61 samples) of RMSEC = 0.753 (R2 = 0.893) and a root mean squared error for validation (with 30 samples) of RMSEV = 0.574. The prediction model was applied on a pixel-by-pixel basis to a Hyperion reflectance image to yield a quantitative surface distribution map of soil salt content. The result was validated successfully from 38 sampling points. We obtained an RMSE estimate of 1.037 (R2 = 0.784) for the soil salt content map derived by the PLSR model. The salinity map derived from the SWR model shows that the predicted value is higher than the true value. These results demonstrate that the PLSR method is a more suitable technique than stepwise regression for quantitative estimation of soil salt content in a large area. ?? 2008 CASI.

  4. Residues of fluoroquinolones in marine aquaculture environment of the Pearl River Delta, South China.

    PubMed

    He, Xiuting; Wang, Zhaohui; Nie, Xiangping; Yang, Yufen; Pan, Debo; Leung, Anna O W; Cheng, Zhang; Yang, Yongtao; Li, Kaibin; Chen, Kunci

    2012-06-01

    Concentrations and distributions of selected fluoroquinolones (norfloxacin, ciprofloxacin and enrofloxacin) in water, sediments and nine kinds of fish species collected from 6 sites in two marine aquaculture regions of the Pearl River Delta, China, were analyzed by using high-performance liquid chromatography with fluorescence detector (HPLC). The results showed that the concentrations of ciprofloxacin and enrofloxacin were below the limits of quantification (LOQ) in all water samples except for norfloxacin. Norfloxacin and ciprofloxacin concentrations ranged from 1.88 to 11.20 ng g(-1) dry wt, 0.76-2.42 ng g(-1) dry wt in sediments collected from the Dapeng'ao region (sites 1-3) and ranged from 2.31 to 4.75 ng g(-1) dry wt, 1.26-1.76 ng g(-1) dry wt in sediments collected from the Hailing Island region (sites 4-6), respectively. However, no enrofloxacin was found in all sediment samples. The three fluoroquinolones (FQs) were detected in all fish samples, and the concentrations were higher in liver tissues than those in muscle tissues. The levels of norfloxacin were higher than ciprofloxacin and enrofloxacin in both liver and muscle tissues. Among the nine marine fish species, Siganus fuscescens from Hailing Island had a significantly high level of norfloxacin in liver tissue (254.58 ng g(-1) wet wt), followed by Sparus macrocephalus (133.15 ng g(-1) wet wt) from Dapeng'ao, and the lowest value was Lutianus argentimaculatus (5.18 ng g(-1) wet wt) from Hailing Island. The obtained results of FQs in present study do not represent a risk to the human health in Guangdong coastal area, based on the maximum residue limits (MRLs) established by Chinese Government and the acceptable daily intake (ADI) recommended by the Food and Agriculture Organization and World Health Organization (FAO/WHO).

  5. [Influence of Burning Fireworks on Air Quality During the Spring Festival in the Pearl River Delta].

    PubMed

    Zhao, Wei; Fan, Shao-jia; Xie, Wen-zhang; Sun, Jia-ren

    2015-12-01

    Based on data from the air quality monitoring stations in the Pearl River Delta during the 2015 Spring Festival, the regional air quality was investigated and the impact of burning fireworks on urban air quality was assessed. The results showed that: Zhaoqing was the worst polluted city in PM₁₀, PM₂.₅, SO₂ and CO in terms of concentrations in the region during the period, Huizhou was the worst polluted city in O₃ and Guangzhou was the most polluted city in NO₂ at the same time. Compared to the data of last year, the SO₂, NO₂, CO, PM₁₀ and PM₂.₅ concentrations had decreased significantly, but the O₃ concentration had increased during the Spring Festival. Burning fireworks during the Spring Festival were mainly concentrated in the suburbs. The concentrated discharge of fireworks made the SO₂, PM₁₀ and PM₂.₅ concentrations increased significantly in the New Year's Eve night, even multiplied, but had no significant effect on CO, O₃ and NO₂. The rapid decline in PM₂.₅/PM₁₀ proportion was caused by the discharge of fireworks, and the ratio of PM₂.₅/PM₁₀ reached the minimum when concentration of particles reached the peak. By assessing, the maximum contribution of hourly concentration from burning fireworks in each city was between 16 µg · m⁻³ and 65 µg · m⁻³ for PM₂.₅, between 28 µg · m⁻³ and 138 µg · m⁻³ for PM₁₀ and between 9 µg · m⁻³ and 43 µg · m⁻³ for SO₂. PMID:27011968

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

    NASA Astrophysics Data System (ADS)

    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.

  7. Landscape ecological security assessment based on projection pursuit in Pearl River Delta.

    PubMed

    Gao, Yang; Wu, Zhifeng; Lou, Quansheng; Huang, Huamei; Cheng, Jiong; Chen, Zhangli

    2012-04-01

    Regional landscape ecological security is an important issue for ecological security, and has a great influence on national security and social sustainable development. The Pearl River Delta (PRD) in southern China has experienced rapid economic development and intensive human activities in recent years. This study, based on landscape analysis, provides a method to discover the alteration of character among different landscape types and to understand the landscape ecological security status. Based on remotely sensed products of the Landsat 5 TM images in 1990 and the Landsat 7 ETM+ images in 2005, landscape classification maps of nine cities in the PRD were compiled by implementing Remote Sensing and Geographic Information System technology. Several indices, including aggregation, crush index, landscape shape index, Shannon's diversity index, landscape fragile index, and landscape security adjacent index, were applied to analyze spatial-temporal characteristics of landscape patterns in the PRD. A landscape ecological security index based on these outcomes was calculated by projection pursuit using genetic algorithm. The landscape ecological security of nine cities in the PRD was thus evaluated. The main results of this research are listed as follows: (1) from 1990 to 2005, the aggregation index, crush index, landscape shape index, and Shannon's diversity index of nine cities changed little in the PRD, while the landscape fragile index and landscape security adjacent index changed obviously. The landscape fragile index of nine cities showed a decreasing trend; however, the landscape security adjacent index has been increasing; (2) from 1990 to 2005, landscape ecology of the cities of Zhuhai and Huizhou maintained a good security situation. However, there was a relatively low value of ecological security in the cities of Dongguan and Foshan. Except for Foshan and Guangzhou, whose landscape ecological security situation were slightly improved, the cities had reduced

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

    PubMed

    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.

  9. Bioactive and total endotoxins in atmospheric aerosols in the Pearl River Delta region, China

    NASA Astrophysics Data System (ADS)

    Cheng, Jessica Y. W.; Hui, Esther L. C.; Lau, Arthur P. S.

    2012-02-01

    Endotoxin, a toxic and pyrogenic substance in gram-negative bacteria in atmospheric aerosols was measured over a period of one year at Nansha, Guangzhou and Hong Kong in the Pearl River Delta region, China. Atmospheric aerosols were collected by high-volume samplers. The bioactive endotoxin levels in the samples were determined using the Limulus Amebocyte Lysate (LAL) assay after extraction with pyrogen-free water while the total endotoxin levels were measured by quantifying the biomarker, 3-hydroxy fatty acids (3-OHFAs) with GC-MS. Results showed that there was no significant difference (0.19 < p < 0.81) in the bioactive endotoxin level in PM 10 among sites (average concentrations ranged from 0.34 to 0.39 EU m -3). However, Hong Kong showed a significantly lower ( p < 0.05) total endotoxin level in PM 10 (average of 17.4 ng m -3) compared with Nansha's 29.4 ng m -3 and Guangzhou's 32.7 ng m -3. The bioactive endotoxins were found to be associated with the coarse mode (PM 2.5-10) of the particulates of natural origins while the total endotoxins were associated more with the fine mode (PM 2.5) of the particulates of anthropogenic origins. When normalized with particulate mass, the endotoxin loading is much higher in summer as a result of the increased growth of the bacteria when climatic conditions are favorable. The chemically determined total endotoxins were 3-4 orders of magnitude higher than the bioactive endotoxins quantified using the LAL assay. Correlation analyses between the bioactive endotoxins and 3-OHFAs with different carbon length were analyzed. Results showed that the correlations detected vary among sites and particulate sizes. Although no generalization between the total and bioactive endotoxins can be drawn from the study, the levels reported in this study suggests that the discrepancies between the two measurement approaches, and the bioactive potential of 3-OHFAs with individual carbon chains deserve further investigation.

  10. Characteristics and applications of size-segregated biomass burning tracers in China's Pearl River Delta region

    NASA Astrophysics Data System (ADS)

    Zhang, Zhisheng; Gao, Jian; Engling, Guenter; Tao, Jun; Chai, Fahe; Zhang, Leiming; Zhang, Renjian; Sang, Xuefang; Chan, Chuen-yu; Lin, Zejian; Cao, Junji

    2015-02-01

    Biomass burning activities in China are ubiquitous and the resulting smoke emissions may pose considerable threats to human health and the environment. In the present study, size-segregated biomass burning tracers, including anhydrosugars (levoglucosan (LG) and mannosan (MN)) and non-sea-salt potassium (nss-K+), were determined at an urban and a suburban site in the Pearl River Delta (PRD) region. The size distributions of biomass burning tracers were generally characterized by a unimodal pattern peaking in the particle size range of 0.44-1.0 μm, except for MN during the wet season, for which a bimodal pattern (one in fine and one in coarse mode) was observed. These observed biomass burning tracers in the PRD region shifted towards larger particle sizes compared to the typical size distributions of fresh biomass smoke particles. Elevated biomass burning tracers were observed during the dry season when biomass burning activities were intensive and meteorological conditions favored the transport of biomass smoke particles from the rural areas in the PRD and neighboring areas to the sampling sites. The fine mode biomass burning tracers significantly correlated with each other, confirming their common sources. Rather high ΔLG/ΔMN ratios were observed at both sites, indicating limited influence from softwood combustion. High Δnss-K+/ΔLG ratios further suggested that biomass burning aerosols in the PRD were predominately associated with burning of crop residues. Using a simplified receptor-oriented approach with an emission factor of 0.075 (LG/TC) obtained from several chamber studies, average contributions of biomass burning emissions to total carbon in fine particles were estimated to be 23% and 16% at the urban and suburban site, respectively, during the dry season. In contrast, the relative contributions to total carbon were lower than 8% at both sites during the wet season.

  11. Heavy metals in agricultural soils of the Pearl River Delta, South China.

    PubMed

    Wong, S C; Li, X D; Zhang, G; Qi, S H; Min, Y S

    2002-01-01

    There is a growing public concern over the potential accumulation of heavy metals in agricultural soils in China owing to rapid urban and industrial development and increasing reliance on agrochemicals in the last several decades. Excessive accumulation of heavy metals in agricultural soils may not only result in environmental contamination, but elevated heavy metal uptake by crops may also affect food quality and safety. The present study is aimed at studying heavy metal concentrations of crop, paddy and natural soils in the Pearl River Delta, one of the most developed regions in China. In addition, some selected soil samples were analyzed for chemical partitioning of Co, Cu, Pb and Zn. The Pb isotopic composition of the extracted solutions was also determined. The analytical results indicated that the crop, paddy and natural soils in many sampling sites were enriched with Cd and Pb. Furthermore, heavy metal enrichment was most significant in the crop soils, which might be attributed to the use of agrochemicals. Flooding of the paddy soils and subsequent dissolution of Mn oxides may cause the loss of Cd and Co through leaching and percolation, resulting in low Cd and Co concentrations of the paddy soils. The chemical partitioning patterns of Pb, Zn and Cu indicated that Pb was largely associated with the Fe-Mn oxide and residual fractions, while Zn was predominantly found in the residual phase. A significant percent fraction of Cu was bound in the organic/sulphide and residual phases. Based on the 206Pb/207Pb ratios of the five fractions, it was evident that some of the soils were enriched with anthropogenic Pb, such as industrial and automobile Pb. The strong associations between anthropogenic Pb and the Fe-Mn oxide and organic/sulphide phases suggested that anthropogenic Pb was relatively stable after deposition in soils. PMID:12125727

  12. Response of Soil Fungi Community Structure to Salt Vegetation Succession in the Yellow River Delta.

    PubMed

    Wang, Yan-Yun; Guo, Du-Fa

    2016-10-01

    High-throughput sequencing technology was used to reveal the composition and distribution of fungal community structure in the Yellow River Delta under bare land and four kinds of halophyte vegetation (saline seepweed, Angiospermae, Imperata and Apocynum venetum [A. venetum]). The results showed that the soil quality continuously improved with the succession of salt vegetation types. The soil fungi richness of mild-salt communities (Imperata and A. venetum) was relatively higher, with Shannon index values of 5.21 and 5.84, respectively. The soil fungi richness of severe-salt-tolerant communities (saline seepweed, Angiospermae) was relatively lower, with Shannon index values of 4.64 and 4.66, respectively. The UniFrac metric values ranged from 0.48 to 0.67 when the vegetation was in different succession stages. A total of 60,174 valid sequences were obtained for the five vegetation types, and they were classified into Ascomycota, Basidiomycota, Chytridiomycota, Glomeromycota and Mucoromycotina. Ascomycota had the greatest advantage among plant communities of Imperata and A. venetum, as indicated by relative abundances of 2.69 and 69.97 %, respectively. Basidiomycota had the greatest advantage among mild-salt communities of saline seepweed and Angiospermae, with relative abundances of 9.43 and 6.64 %, respectively. Soil physical and chemical properties were correlated with the distribution of the fungi, and Mucor was significantly correlated with soil moisture (r = 0.985; P < 0.01). Soil quality, salt vegetation and soil fungi were influenced by each other.

  13. Response of Soil Fungi Community Structure to Salt Vegetation Succession in the Yellow River Delta.

    PubMed

    Wang, Yan-Yun; Guo, Du-Fa

    2016-10-01

    High-throughput sequencing technology was used to reveal the composition and distribution of fungal community structure in the Yellow River Delta under bare land and four kinds of halophyte vegetation (saline seepweed, Angiospermae, Imperata and Apocynum venetum [A. venetum]). The results showed that the soil quality continuously improved with the succession of salt vegetation types. The soil fungi richness of mild-salt communities (Imperata and A. venetum) was relatively higher, with Shannon index values of 5.21 and 5.84, respectively. The soil fungi richness of severe-salt-tolerant communities (saline seepweed, Angiospermae) was relatively lower, with Shannon index values of 4.64 and 4.66, respectively. The UniFrac metric values ranged from 0.48 to 0.67 when the vegetation was in different succession stages. A total of 60,174 valid sequences were obtained for the five vegetation types, and they were classified into Ascomycota, Basidiomycota, Chytridiomycota, Glomeromycota and Mucoromycotina. Ascomycota had the greatest advantage among plant communities of Imperata and A. venetum, as indicated by relative abundances of 2.69 and 69.97 %, respectively. Basidiomycota had the greatest advantage among mild-salt communities of saline seepweed and Angiospermae, with relative abundances of 9.43 and 6.64 %, respectively. Soil physical and chemical properties were correlated with the distribution of the fungi, and Mucor was significantly correlated with soil moisture (r = 0.985; P < 0.01). Soil quality, salt vegetation and soil fungi were influenced by each other. PMID:27449214

  14. Aerosol optical properties and mixing state of black carbon in the Pearl River Delta, China

    NASA Astrophysics Data System (ADS)

    Tan, Haobo; Liu, Li; Fan, Shaojia; Li, Fei; Yin, Yan; Cai, Mingfu; Chan, P. W.

    2016-04-01

    Aerosols contribute the largest uncertainty to the total radiative forcing estimate, and black carbon (BC) that absorbs solar radiation plays an important role in the Earth's energy budget. This study analysed the aerosol optical properties from 22 February to 18 March 2014 at the China Meteorological Administration Atmospheric Watch Network (CAWNET) station in the Pearl River Delta (PRD), China. The representative values of dry-state particle scattering coefficient (σsp), hemispheric backscattering coefficient (σhbsp), absorption coefficient (σabsp), extinction coefficient (σep), hemispheric backscattering fraction (HBF), single scattering albedo (SSA), as well as scattering Ångström exponent (α) were presented. A comparison between a polluted day and a clean day shows that the aerosol optical properties depend on particle number size distribution, weather conditions and evolution of the mixing layer. To investigate the mixing state of BC at the surface, an optical closure study of HBF between measurements and calculations based on a modified Mie model was employed for dry particles. The result shows that the mixing state of BC might be between the external mixture and the core-shell mixture. The average retrieved ratio of the externally mixed BC to the total BC mass concentration (rext-BC) was 0.58 ± 0.12, and the diurnal pattern of rext-BC can be found. Furthermore, considering that non-light-absorbing particles measured by a Volatility-Tandem Differential Mobility Analyser (V-TDMA) exist independently with core-shell and homogenously internally mixed BC particles, the calculated optical properties were just slightly different from those based on the assumption that BC exist in each particle. This would help understand the influence of the BC mixing state on aerosol optical properties and radiation budget in the PRD.

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

    PubMed

    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. PMID:24631615

  16. Landscape ecological security assessment based on projection pursuit in Pearl River Delta.

    PubMed

    Gao, Yang; Wu, Zhifeng; Lou, Quansheng; Huang, Huamei; Cheng, Jiong; Chen, Zhangli

    2012-04-01

    Regional landscape ecological security is an important issue for ecological security, and has a great influence on national security and social sustainable development. The Pearl River Delta (PRD) in southern China has experienced rapid economic development and intensive human activities in recent years. This study, based on landscape analysis, provides a method to discover the alteration of character among different landscape types and to understand the landscape ecological security status. Based on remotely sensed products of the Landsat 5 TM images in 1990 and the Landsat 7 ETM+ images in 2005, landscape classification maps of nine cities in the PRD were compiled by implementing Remote Sensing and Geographic Information System technology. Several indices, including aggregation, crush index, landscape shape index, Shannon's diversity index, landscape fragile index, and landscape security adjacent index, were applied to analyze spatial-temporal characteristics of landscape patterns in the PRD. A landscape ecological security index based on these outcomes was calculated by projection pursuit using genetic algorithm. The landscape ecological security of nine cities in the PRD was thus evaluated. The main results of this research are listed as follows: (1) from 1990 to 2005, the aggregation index, crush index, landscape shape index, and Shannon's diversity index of nine cities changed little in the PRD, while the landscape fragile index and landscape security adjacent index changed obviously. The landscape fragile index of nine cities showed a decreasing trend; however, the landscape security adjacent index has been increasing; (2) from 1990 to 2005, landscape ecology of the cities of Zhuhai and Huizhou maintained a good security situation. However, there was a relatively low value of ecological security in the cities of Dongguan and Foshan. Except for Foshan and Guangzhou, whose landscape ecological security situation were slightly improved, the cities had reduced

  17. Abundance and patterns of transparent exopolymer particles (TEP) in Arctic floodplain lakes of the Mackenzie River Delta

    NASA Astrophysics Data System (ADS)

    Chateauvert, C. Adam; Lesack, Lance F. W.; Bothwell, Max L.

    2012-12-01

    The Mackenzie River Delta is a lake-rich arctic floodplain that receives high inputs of dissolved organic matter (DOM) and suspended particulates from allochthonous and autochthonous sources, and may transfer carbon from dissolved to particulate phase via in situ formation of transparent exopolymer particles (TEP). TEP provides food for grazers, surfaces for bacteria, and increased potential for aggregation and sedimentation of organic matter. During open water 2006, we tracked TEP abundances in three Delta lakes representing gradients that include declining river-to-lake connection times, increasing levels of dissolved organic carbon (DOC), and declining chromophoric-DOM (CDOM). Unexpectedly, TEP abundances were highest immediately after the flood, when autochthonous autotrophic production was at a seasonal low and CDOM a seasonal high. Moreover, the lake with the strongest riverine influence and lowest levels of autochthonous autotrophic production had the highest mean TEP-carbon (TEP-C) concentrations among the lakes. The mean proportion of particulate organic carbon (POC) represented by TEP-C increased with increasing river connection time, and appears to represent a substantial proportion of POC in Mackenzie Delta Lakes. Unexpectedly, the TEP gradient was most strongly related to CDOM (river water source) rather than overall DOC. Variations in CDOM accounted for 53% of TEP-C variation among the lakes, indicating allochthonous matter was the most important source of TEP. DOC release from in situ macrophytes during periods of high photosynthesis may contribute to TEP formation in the lake with lowest riverine influence, but pH levels >9.5 driven by the high photosynthetic rates complicate the interpretation of results from this lake.

  18. Exploiting sedimentation datasets to model the impact of sediment loading on sea level at the Yellow River Delta

    NASA Astrophysics Data System (ADS)

    Pico, T.; Mitrovica, J. X.; Ferrier, K.

    2015-12-01

    In order to accurately depict glacial isostatic adjustment (GIA) of the solid Earth and consequent sea level, it is necessary to incorporate the loading and unloading of the crust occurring over glacial cycles in the form of sediment erosion and deposition. The inclusion of sediment loading in GIA models becomes even more imperative when studying sea level at densely populated centers along coastlines, many of which are located at large river deltas. Sediment deposition at deltas influences sea level by introducing a load, which in turn alters crustal elevation and perturbs the gravitational field. These sediment loads vary in space and time over glacial cycles, as deltas prograde during sea-level highstands and shelves are exposed during lowstands. The Yellow River serves as an archetypical case study of fluvial response to glacial cycles. Draining the highly erodible, glacially derived Loess Plateau, the Yellow River's sediment flux is the 2nd highest in the world. This site provides an ideal location for modeling sediment loads in order to investigate how glacial cycles control sedimentation history and regional sea level. This study employs datasets constraining deposition and erosion that are physically recorded in dated sediment cores, seismic sections, and river flux measurements. These sedimentary datasets elucidate how loading varies spatially and with time in the basin, but also, importantly, data of fossil-bearing cores act to constrain sea level history during this period. Thus, we utilize physical sedimentary data as both an input to our model and a check on the predicted local sea level. Our gravitationally self-consistent global model is then capable of exploring and constraining how evolving sediment loads and migrating depositional centers impact local predicted crustal deformation, and therefore sea-level, over glacial timescales.

  19. Effect of river sediment on phosphorus chemistry of similarly aged natural and created wetlands in the Atchafalaya Delta, Louisiana, USA.

    PubMed

    Poach, M E; Faulkner, S P

    2007-01-01

    The goal of wetland creation is to produce an artificial wetland that functions as a natural wetland. Studies comparing created wetlands to similarly aged natural wetlands provide important information about creation techniques and their improvement so as to attain that goal. We hypothesized that differences in sediment phosphorus accretion, deposition, and chemistry between created and natural wetlands in the Atchafalaya Delta, Louisiana, USA were a function of creation technique and natural river processes. Sediment deposition was determined with feldspar marker horizons located in created and natural wetlands belonging to three age classes (<3, 5-10, and 15-20 yr old). Phosphorus fractions were measured in these deposited sediments and in suspended and bedload sediment from the Atchafalaya River. Bedload sediment had significantly lower iron- and aluminum-bound, reductant-soluble, and total phosphorus than suspended sediment due to its high sand percentage. This result indicates that wetlands artificially created in the Atchafalaya Delta using bedload sediment will initially differ from natural wetlands of the same age. Even so, similarities between the mudflat stratum of the <1- to 3-yr-old created wetland and the mudflat stratum of the 15- to 20-yr-old natural wetland support the contention that created wetlands in the Atchafalaya Delta can develop natural characteristics through the deposition of river suspended sediment. Differences between three created wetland strata, the 15- to 20-yr-old willow stratum and the <1- to 3-yr-old willow and mixed marsh strata, and their natural counterparts were linked to design elements of the created wetlands that prevented the direct deposition of the river's suspended sediment.

  20. Effect of river sediment on phosphorus chemistry of similarly aged natural and created wetlands in the Atchafalaya Delta, Louisiana, USA

    USGS Publications Warehouse

    Poach, M.E.; Faulkner, S.P.

    2007-01-01

    The goal of wetland creation is to produce an artificial wetland that functions as a natural wetland. Studies comparing created wetlands to similarly aged natural wetlands provide important information about creation techniques and their improvement so as to attain that goal. We hypothesized that differences in sediment phosphorus accretion, deposition, and chemistry between created and natural wetlands in the Atchafalaya Delta, Louisiana, USA were a function of creation technique and natural river processes. Sediment deposition was determined with feldspar marker horizons located in created and natural wetlands belonging to three age classes (<3, 5-10, and 15-20 yr old). Phosphorus fractions were measured in these deposited sediments and in suspended and bedload sediment from the Atchafalaya River. Bedload sediment had significantly lower iron- and aluminum-bound, reductant-soluble, and total phosphorus than suspended sediment due to its high sand percentage. This result indicates that wetlands artificially created in the Atchafalaya Delta using bedload sediment will initially differ from natural wetlands of the same age. Even so, similarities between the mudflat stratum of the <1- to 3-yr-old created wetland and the mudflat stratum of the 15- to 20-yr-old natural wetland support the contention that created wetlands in the Atchafalaya Delta can develop natural characteristics through the deposition of river suspended sediment. Differences between three created wetland strata, the 15- to 20-yr-old willow stratum and the < 1- to 3-yr-old willow and mixed marsh strata, and their natural counterparts were linked to design elements of the created wetlands that prevented the direct deposition of the river's suspended sediment. ?? ASA, CSSA, SSSA.

  1. A Groundwater flow Model of the Colorado River Delta to Support Riparian Habitat Restoration in Northern Mexico

    NASA Astrophysics Data System (ADS)

    Maddock, T.; Feirstein, E.; Baird, K. J.; Ajami, H.

    2007-05-01

    Quantification of groundwater flow dynamics and of the interactions among groundwater, surface water, and riparian vegetation, represent key components in the development of a balanced restoration plan for functional riparian ecosystems. A groundwater model was developed using MODFLOW 2000 to support of riparian restoration along the Colorado River Delta (Mexico: Baja California, Sonora). The Colorado River is widely recognized as one of the most modified and allocated rivers in the United States. For over 50 years flows into the Delta were severely reduced by the requirements of an emergent American West. However, subsequent to discharge pulses associated with the filling of Lake Powell, and the increased precipitation that accompanied ENSO cycles, a semblance of a native riparian habitat has been observed in the Delta since the 1980's (Zamora- Arroyo et al. 2001). The Delta and the riparian ecosystems of the region have since become the focus of a substantial body of multidisciplinary research. The research goal is to understand water table dynamics with particular attention to stream-aquifer interactions and groundwater behavior in the root zone. Groundwater reliant transpiration requirements were quantified for a set of dominant native riparian species using the Riparian ET (RIP-ET) package, an improved MODFLOW evapotranspiration (ET) module. RIP-ET simulates ET using a set of eco-physiologically based curves that more accurately represents individual plant species, reflects habitat complexity, and deals spatially with plant and water table distribution. When used in conjunction with a GIS based postprocessor (RIP-GIS.net), RIP-ET provides the basis for mapping groundwater conditions as they relate to user-specified plant groups. This explicit link between groundwater and plant sustainability is a driver to restoration design and allows for scenario modeling of various hydrologic conditions. Groundwater requirements determined in this research will be used by

  2. Sinking Coastlines: Land Subsidence at Aquaculture Facilities in the Yellow River Delta, China, measured with Differential Synthetic Aperture Radar (D-InSAR)

    NASA Astrophysics Data System (ADS)

    Higgins, S.; Overeem, I.; Tanaka, A.; Syvitski, J. P.

    2013-12-01

    Land subsidence in river deltas is a global problem. It heightens storm surges, salinates groundwater, intensifies river flooding, destabilizes infrastructure and accelerates shoreline retreat. Measurements of delta subsidence typically rely on point measures such as GPS devices, tide gauges or extensometers, but spatial coverage is needed to fully assess risk across river deltas. Differential Interferometric Synthetic Aperture Radar (D-InSAR) is a satellite-based technique that can provide maps of ground deformation with mm to cm-scale vertical resolution. We apply D-InSAR to the coast of the Yellow River Delta in China, which is dominated by aquaculture facilities and has experienced severe coastal erosion in the last twenty years. We extract deformation patterns from dry land adjacent to aquaculture facilities along the coast, allowing the first measurements of subsidence at a non-urban delta shoreline. Results show classic cones-of-depression surrounding aquaculture facilities, likely due to groundwater pumping. Subsidence rates are as high as 250 mm/y at the largest facility on the delta. These rates exceed local and global average sea level rise by nearly two orders of magnitude. If these rates continue, large aquaculture facilities in the area could induce more than a meter of relative sea level rise every five years. Given the global explosion in fish farming in recent years, these results also suggest that similar subsidence and associated relative sea level rise may present a significant hazard for other Asian megadeltas. False-color MODIS image of the Yellow River delta in September 2012. Water appears dark blue, highlighting the abundance of aquaculture facilities along the coast. Green land is primarily agricultural; brown is urban. Red boxes indicate locations of aquaculture facilities examined in this study. Figure from Higgins, S., Overeem, I., Tanaka, A., & Syvitski, J.P.M., (2013), Land Subsidence at Aquaculture Facilities in the Yellow River

  3. MODELING THE IMPACTS OF DECADAL CHANGES IN RIVERINE NUTRIENT FLUXES ON COASTAL EUTROPHICATION NEAR THE MISSISSIPPI RIVER DELTA. (R827785E02)

    EPA Science Inventory

    A mathematical model was used to link decadal changes in the Mississippi River nutrient flux to coastal eutrophication near the Mississippi River Delta. Model simulations suggest that bottom water hypoxia intensified about 30 years ago, as a probable consequence of increased n...

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

    SciTech Connect

    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.

  5. A preliminary study on the occurrence and behavior of carbamazepine (CBZ) in aquatic environment of Yangtze River Delta, China.

    PubMed

    Zhou, X F; Dai, C M; Zhang, Y L; Surampalli, R Y; Zhang, T C

    2011-02-01

    The occurrence and behavior of carbamazepine (CBZ) was investigated in aquatic environment of Yangtze River Delta, East China. The water samples were enriched by solid-phase extraction and analyzed by high-performance liquid chromatography with diode array detector. The validation of the analytical method included linearity (0.1-1 mg/L), recovery studies, and determination of limits of quantification. Limits of quantification of CBZ in various aquatic samples were in the range of 0.1-0.2 μg/L. CBZ was detected in the Tongji University Intramural River, the Huangpu River, and the Suzhou River with the highest concentration of 1,090 ng/L, but not detected in the Nanhengyin River and the Caojia River. In sewage water samples, CBZ was not detected in one of the sewage treatment plants (STPs) but was detected in the raw influents and effluents at the other three selected STPs in Shanghai, with the concentrations ranging from 230 to 1,110 ng/L. CBZ was not completely eliminated after secondary treatment (with the active sludge process).

  6. Pelagic biological processes along a salinity gradient in the Fly delta and adjacent river plume (Papua New Guinea)

    NASA Astrophysics Data System (ADS)

    Robertson, A. I.; Daniel, P. A.; Dixon, P.; Alongi, D. M.

    1993-02-01

    We measured planktonic processes (primary and bacterial production, respiration) and concentrations of suspended material, nutrients, chlorophyll a, floating macroparticulate matter, zooplankton and neuston in the delta and river plume of the Fly River in Papua New Guinea in July/August 1989 and February 1990. There appeared to be conservative mixing of dissolved nutrients across the salinity gradient, but there were seasonal differences in nitrate and phosphate concentrations in freshwater entering the estuary. Phosphate concentrations (>5 μM) in freshwater entering the estuary during July/August were higher than in most large tropical rivers. Concentrations of suspended solids in the estuary and plume ranged from 82 to 3312 mg l -1 in July/August and from 2 to 681 mg l -1 in February. Suspended solids were from 1.0 to 33.6% carbon, but the average for most stations was between 2 and 12%. There was an inverse relationship between per cent carbon and the suspended solid concentrations, similar to that observed in the Changjiang estuary. The mean C:N ratio for suspended solids for most stations was from 4 to 21 (mean 7.3). Mean floating macroparticulate matter biomass in the estuary was 80 mg C m -3 (2.2 mg N m -3). Mean chlorophyll a concentrations in estuary and plume stations ranged from 0.25 to 5.07 and from 0.32 to 0.73 μg l -1, respectively. Phytoplankton blooms (chlorophyll a up to 5.07 μg l -1) occurred just inside the mouth of the delta where suspended solids were ≤70 mg l -1. In February, net primary production in the oligohaline regions of the delta ranged from 22 to 94 mg C m -2 day -1, but highest production (up to 693 mg C m -2 day -1) was recorded at the most seaward stations in the delta. In the plume, in situ production ranged from 227 to 340 mg C m -2 day -1. Community respiration (0.8-36 g C m -2 day -1) across the salinity gradient was typically 1-2 orders of magnitude higher than in situ production. Bacterial production rates ranged from 0

  7. Resistance to Acephate in Tarnished Plant Bug (Heteroptera: Miridae) Populations in the Mississippi River Delta

    Technology Transfer Automated Retrieval System (TEKTRAN)

    A monitoring program to detect resistance in tarnished plant bug, Lygus lineolaris (Palisot de Beauvois), populations in the delta of AR, LA, and MS, was conducted by testing populations collected from weeds with a glass-vial bioassay at 20 different delta locations from the fall of 2001 through the...

  8. Characterizing baseline concentrations, proportions, and processes controlling deposition of river-transported bitumen-associated polycyclic aromatic compounds at a floodplain lake (Slave River Delta, Northwest Territories, Canada).

    PubMed

    Elmes, Matthew C; Wiklund, Johan A; Van Opstal, Stacey R; Wolfe, Brent B; Hall, Roland I

    2016-05-01

    Inadequate knowledge of baseline conditions challenges ability for monitoring programs to detect pollution in rivers, especially where there are natural sources of contaminants. Here, we use paleolimnological data from a flood-prone lake ("SD2", informal name) in the Slave River Delta (SRD, Canada), ∼ 500 km downstream of the Alberta oil sands development and the bitumen-rich McMurray Formation to identify baseline concentrations and proportions of "river-transported bitumen-associated indicator polycyclic aromatic compounds" (indicator PACs; Hall et al. 2012) and processes responsible for their deposition. Results show that indicator PACs are deposited in SD2 by Slave River floodwaters in concentrations that are 45 % lower than those in sediments of "PAD31compounds", a lake upstream in the Athabasca Delta that receives Athabasca River floodwaters. Lower concentrations at SD2 are likely a consequence of sediment retention upstream as well as dilution by sediment influx from the Peace River. In addition, relations with organic matter content reveal that flood events dilute concentrations of indicator PACs in SD2 because the lake receives high-energy floods and the lake sediments are predominantly inorganic. This contrasts with PAD31 where floodwaters increase indicator PAC concentrations in the lake sediments, and concentrations are diluted during low flood influence intervals due to increased deposition of lacustrine organic matter. Results also show no significant differences in concentrations and proportions of indicator PACs between pre- (1967) and post- (1980s and 1990 s) oil sands development high flood influence intervals (t = 1.188, P = 0.279, d.f. = 6.136), signifying that they are delivered to the SRD by natural processes. Although we cannot assess potential changes in indicator PACs during the past decade, baseline concentrations and proportions can be used to enhance ongoing monitoring efforts. PMID:27071660

  9. Characterizing baseline concentrations, proportions, and processes controlling deposition of river-transported bitumen-associated polycyclic aromatic compounds at a floodplain lake (Slave River Delta, Northwest Territories, Canada).

    PubMed

    Elmes, Matthew C; Wiklund, Johan A; Van Opstal, Stacey R; Wolfe, Brent B; Hall, Roland I

    2016-05-01

    Inadequate knowledge of baseline conditions challenges ability for monitoring programs to detect pollution in rivers, especially where there are natural sources of contaminants. Here, we use paleolimnological data from a flood-prone lake ("SD2", informal name) in the Slave River Delta (SRD, Canada), ∼ 500 km downstream of the Alberta oil sands development and the bitumen-rich McMurray Formation to identify baseline concentrations and proportions of "river-transported bitumen-associated indicator polycyclic aromatic compounds" (indicator PACs; Hall et al. 2012) and processes responsible for their deposition. Results show that indicator PACs are deposited in SD2 by Slave River floodwaters in concentrations that are 45 % lower than those in sediments of "PAD31compounds", a lake upstream in the Athabasca Delta that receives Athabasca River floodwaters. Lower concentrations at SD2 are likely a consequence of sediment retention upstream as well as dilution by sediment influx from the Peace River. In addition, relations with organic matter content reveal that flood events dilute concentrations of indicator PACs in SD2 because the lake receives high-energy floods and the lake sediments are predominantly inorganic. This contrasts with PAD31 where floodwaters increase indicator PAC concentrations in the lake sediments, and concentrations are diluted during low flood influence intervals due to increased deposition of lacustrine organic matter. Results also show no significant differences in concentrations and proportions of indicator PACs between pre- (1967) and post- (1980s and 1990 s) oil sands development high flood influence intervals (t = 1.188, P = 0.279, d.f. = 6.136), signifying that they are delivered to the SRD by natural processes. Although we cannot assess potential changes in indicator PACs during the past decade, baseline concentrations and proportions can be used to enhance ongoing monitoring efforts.

  10. Beach morphology and change along the mixed grain-size delta of the dammed Elwha River, Washington

    NASA Astrophysics Data System (ADS)

    Warrick, Jonathan A.; George, Douglas A.; Gelfenbaum, Guy; Ruggiero, Peter; Kaminsky, George M.; Beirne, Matt

    2009-10-01

    Sediment supply provides a fundamental control on the morphology of river deltas, and humans have significantly modified these supplies for centuries. Here we examine the effects of almost a century of sediment supply reduction from the damming of the Elwha River in Washington on shoreline position and beach morphology of its wave-dominated delta. The mean rate of shoreline erosion during 1939-2006 is ~ 0.6 m/yr, which is equivalent to ~ 24,000 m 3/yr of sediment divergence in the littoral cell, a rate approximately equal to 25-50% of the littoral-grade sediment trapped by the dams. Semi-annual surveys between 2004 and 2007 show that most erosion occurs during the winter with lower rates of change in the summer. Shoreline change and morphology also differ spatially. Negligible shoreline change has occurred updrift (west) of the river mouth, where the beach is mixed sand to cobble, cuspate, and reflective. The beach downdrift (east) of the river mouth has had significant and persistent erosion, but this beach differs in that it has a reflective foreshore with a dissipative low-tide terrace. Downdrift beach erosion results from foreshore retreat, which broadens the low-tide terrace with time, and the rate of this kind of erosion has increased significantly from ~ 0.8 m/yr during 1939-1990 to ~ 1.4 m/yr during 1990-2006. Erosion rates for the downdrift beach derived from the 2004-2007 topographic surveys vary between 0 and 13 m/yr, with an average of 3.8 m/yr. We note that the low-tide terrace is significantly coarser (mean grain size ~ 100 mm) than the foreshore (mean grain size ~ 30 mm), a pattern contrary to the typical observation of fining low-tide terraces in the region and worldwide. Because this cobble low-tide terrace is created by foreshore erosion, has been steady over intervals of at least years, is predicted to have negligible longshore transport compared to the foreshore portion of the beach, and is inconsistent with oral history of abundant shellfish

  11. Beach morphology and change along the mixed grain-size delta of the dammed Elwha River, Washington

    USGS Publications Warehouse

    Warrick, J.A.; George, D.A.; Gelfenbaum, G.; Ruggiero, P.; Kaminsky, G.M.; Beirne, M.

    2009-01-01

    Sediment supply provides a fundamental control on the morphology of river deltas, and humans have significantly modified these supplies for centuries. Here we examine the effects of almost a century of sediment supply reduction from the damming of the Elwha River in Washington on shoreline position and beach morphology of its wave-dominated delta. The mean rate of shoreline erosion during 1939-2006 is ~ 0.6??m/yr, which is equivalent to ~ 24,000??m3/yr of sediment divergence in the littoral cell, a rate approximately equal to 25-50% of the littoral-grade sediment trapped by the dams. Semi-annual surveys between 2004 and 2007 show that most erosion occurs during the winter with lower rates of change in the summer. Shoreline change and morphology also differ spatially. Negligible shoreline change has occurred updrift (west) of the river mouth, where the beach is mixed sand to cobble, cuspate, and reflective. The beach downdrift (east) of the river mouth has had significant and persistent erosion, but this beach differs in that it has a reflective foreshore with a dissipative low-tide terrace. Downdrift beach erosion results from foreshore retreat, which broadens the low-tide terrace with time, and the rate of this kind of erosion has increased significantly from ~ 0.8??m/yr during 1939-1990 to ~ 1.4??m/yr during 1990-2006. Erosion rates for the downdrift beach derived from the 2004-2007 topographic surveys vary between 0 and 13??m/yr, with an average of 3.8??m/yr. We note that the low-tide terrace is significantly coarser (mean grain size ~ 100??mm) than the foreshore (mean grain size ~ 30??mm), a pattern contrary to the typical observation of fining low-tide terraces in the region and worldwide. Because this cobble low-tide terrace is created by foreshore erosion, has been steady over intervals of at least years, is predicted to have negligible longshore transport compared to the foreshore portion of the beach, and is inconsistent with oral history of abundant

  12. Preconception Health of Reproductive Aged Women of the Mississippi River Delta

    PubMed Central

    Farr, Sherry; Johnson, Dick; McAnally, Ron

    2015-01-01

    Optimal preconception health (PCH) may improve maternal and infant outcomes, priority issues in Mississippi (MS). Our study objective was to compare the PCH of women in the MS Delta to other regions. We analyzed Behavioral Risk Factor Surveillance System data from 2005, 2007, and 2009, and limited analyses to 171,612 non-pregnant black and white women 18–44 years of age. Region was defined as 14 MS Delta counties (MS Delta), remainder of MS (MS non-Delta), Delta states (LA, AR, TN), and non-Delta US states. We calculated adjusted prevalence ratios (aPR) to assess associations between region and 16 indicators of optimal PCH, controlling for demographic characteristics. Healthy PCH factors such as consuming ≥5 fruits and vegetables daily and normal body mass index (18.5 kg/m2 to <25 kg/m2), respectively, were more prevalent in the MS non-Delta (aPR = 1.3; 95 % CI: 1.0,1.7 and aPR = 1.2; 95 % CI: 1.0,1.4), non-MS Delta (aPR = 1.5; 95 % CI: 1.2,2.0 and aPR = 1.3; 95 % CI: 1.1,1.5) and non-Delta states (aPR = 1.7; 95 % CI: 1.3,2.2 and aPR = 1.4; 95 % CI: 1.2,1.6) compared to the MS Delta. Physical activity levels were higher among non-Delta US states compared to the MS Delta (aPR = 1.3; 95 % CI: 1.1,1.4). Household income and race confounded the associations between region and PCH. Reproductive aged women in the MS Delta had poorer PCH, particularly for physical activity and nutrition, than women in other regions. MS Delta service providers and public health practitioners should consider implementing or enhancing lifestyle, nutrition, and physical activity interventions, with a special focus on reducing income-based and racial disparities. PMID:23099798

  13. Understanding the Value of Satellite Altimetry for Monitoring Water Level Dynamics of Large Rivers in Bangladesh Delta

    NASA Astrophysics Data System (ADS)

    Hossain, F.; Akbor, S.; Sustainability, Satellites, Water; Environment (Saswe) Research Group

    2010-12-01

    Although transboundary river flow accounts for more than 40% of global surface flow across 145 nations (many of them water-stressed and conflict-prone), most of this flow is difficult to monitor in developing nations at operational timescales. For Bangladesh, this situation is particularly acute because it comprises only 7% of the entire Ganges-Brahmaputra-Meghna basin and is located at the downstream end of the basin. Thus more than 90% of the water is generated in upstream nations and yet this information is hard to obtain in Bangladesh due to lack of transboundary instrumentation or international treaties. This work therefore investigates the value of satellite radar altimetry in detecting the water level changes for large rivers in the Bangladesh Delta. It is founded on the hypothesis that a satellite altimeter can detect water level to the same accuracy for both inside and outside of Bangladesh. First, the river hydraulic model called HEC-RAS (Hydrologic Engineering Center, River Analysis System) is set up and calibrated over Bangladesh using a comprehensive database on in-situ river bathymetry and observed water level records. Next, the calibrated HEC-RAS model is provided boundary flow conditions upstream and downstream of the model domain. At the upstream end where the Ganges, Brahmaputra and Meghan enter Bangladesh, high resolution flow data modeled from a well calibrated hydrologic model called MIKE BASIN is provided as input. The observed tidal flow records of the Meghna estuary near the Bay of Bengal are used as the downstream boundary conditions. HEC-RAS is then used to simulate daily water level data for the period of 2003-2005 for major rivers of Bangladesh. These water level simulations are directly compared with altimeter estimates of water level from the ENVISAT mission. Accuracy of ENVISAT data is characterized as a function of season, flow regime and river type. The important question that this study aims to answer is, “To what extent can

  14. Distribution of polycyclic musks in surface sediments from the Pearl River Delta and Macao Coastal Region, South china.

    PubMed

    Zeng, Xiangying; Mai, Bixian; Sheng, Guoying; Luo, Xiaojun; Shao, Wenlan; An, Taicheng; Fu, Jiamo

    2008-01-01

    Polycyclic musks were measured in surface sediments collected from the Pearl River Delta and Macao coastal region, South China, to investigate contamination from domestic sewage. Three polycyclic musk compounds-4-acetyl-1,1-dimethyl-6-tert-butylindan, 1,3,4,6,7,8-hexahydro-4,6,6,7,8,8-hexamethylcyclopenta(g)-2-benzopyran (HHCB), and 7-acetyl-1,1,3,4,4,6-hexamethyl-1,2,3,4-tetrahydronaphthalene (AHTN)-were detected in sediment samples. Two polycyclic musks, HHCB and AHTN, were dominant components in sediment, consistent with the use pattern of polycyclic musks by perfume industries in the Pearl River Delta region. The concentrations of total polycyclic musks ranged from 5.76 to 167 microg/kg. Because of the large amount of domestic sewage and industrial wastewater discharged from the city of Guangzhou, the highest concentration of polycyclic musks was found in sediments from the Zhujiang River. The significant positive correlation between the HHCB to AHTN ratios and the concentrations of polycyclic musks suggested that the HHCB to AHTN ratio could be used as a tracer for source discrimination and for the degree of degradation in the environment.

  15. Paleo-Reconstruction of Carbon Cycling in Large-River Delta-Front Estuaries: Use of Molecular Biomarkers

    NASA Astrophysics Data System (ADS)

    Bianchi, T. S.

    2014-12-01

    The burial of organic carbon (OC) in river deltas and continental margins worldwide account for approximately 90% of the carbon burial in the ocean. In particular, sediments in large-river delta-front estuaries have been shown to be repositories and integrators of land-use change across expansive watersheds that drain the continents to the ocean. Thus, separating natural and human-driven changes in the transport of terrestrial organic carbon (TOC) to ocean is important in understanding the effects of climate change on TOC fluxes. Molecular biomarkers of TOC (e.g., lignin phenols, fatty acids, sterols) in LDE sediments have been used extensively to reconstruct of carbon cycling changes that are reflective of land-use change in the watersheds. However, due to the highly variable hydrologic regimes across continents, continental margins (e.g., active versus passive), and coastal dynamics in LDEs, the fate and transport of these molecular biomarkers varies considerably. Here I will discuss some of the key molecular biomarkers that have been used to date in such historical reconstruction exercises in LDEs (e.g., Mississippi/Atchafalaya, Yangtze, Yellow, Ganges-Brahmaputra, Colville Rivers), and explore how margin-type, residence time of transport, redox, and molecular stability, to name a few, impact the utility of using different biomarkers in paleo-reconstruction studies.

  16. Empirical estimates of the dominant environmental forcings on the relative sea level change of river delta systems

    NASA Astrophysics Data System (ADS)

    Tessler, Z. D.; Vorosmarty, C. J.

    2012-12-01

    A global, empirically derived projection of river delta systems at risk of future relative sea level rise is presented based on a set of global environmental risk indicators. Indicators are drawn from upstream basin, coastal zone, and oceanic domains. They include human dimension variables such as population density, urban development, and water engineering, as well as biogeophysical variables such as the local wave environment and cyclone risk. All indicators are hypothesized to have a significant level of direct or indirect control on the local rate of relative sea level rise, commonly through changes in sediment delivery and deposition on the delta plain. Indicators are statistically weighted based on observed rates of relative sea level rise in the literature. These weightings, applied to time series of risk indicators from river network and ocean models and the satellite record, enable identification of regions at greatest risk as a function of time and space. We find regional differences in the dominant sources of sea level rise risk, with higher latitude sites along the Arctic Ocean and in southern Africa and Australia dominated by oceanic risks. In Southeast Asia, the coastal zones with large deltaic megacities dominate ocean and basin source risks, while broadly developed river basins in East Asia and parts of Europe contribute strongly to sea level rise risk in those regions. Future work that will enable rigorous testing of alternative weighting schemes from which overall risk is determined will be discussed.

  17. Changes in the volume of water in the Mississippi River alluvial aquifer in the Delta, northwestern Mississippi, 1980-94

    USGS Publications Warehouse

    Arthur, J.K.

    1995-01-01

    The U.S. Geological Survey, in cooperation with the Mississippi Department of Environmental Quality, Office of Land and Water Resources, and the Natural Resources Conservation Service, estimated the volumetric changes of water in the Mississippi River alluvial aquifer in northwestern Mississippi from 1980 through 1994. Volumetric changes of water in the alluvial aquifer were estimated for the entire Delta and for five selected areas within the Delta. The volume of water per square mile in the alluvial aquifer in the Delta changed from 17,886 acre-feet during fall 1980 to 17,719 acre-feet during fall 1994, a decrease in volume per square mile of 167 acre-feet. The minimum volume of water per square mile in the alluvial aquifer in the Delta during 1980-94 was 17,640 acre-feet during fall 1988. Of five selected areas within the Delta, an area near Cleveland in Bolivar County had the greatest change in volume of water in the alluvial aquifer. During fall 1980 this area had 20,790 acre-feet of water per square mile in the aquifer; by fall 1994, the volume had decreased to 19,947 acre-feet of water per square mile. An area located in the vicinity of the Sunflower-Leflore County line has within its boundaries a large cone of depression in the potentiometric surface of the alluvial aquifer. The volume of water per square mile in this area decreased from 17,857 acre-feet during fall 1980 to 17,075 acre-feet during fall 1994.

  18. Towards up-scaling restored wetland CO2 and CH4 exchange in the Sacramento - San Joaquin River Delta

    NASA Astrophysics Data System (ADS)

    Sturtevant, C. S.; Knox, S. H.; Koteen, L. E.; Matthes, J. H.; Verfaillie, J. G.; Baldocchi, D. D.

    2013-12-01

    Returning agricultural land to wetlands in the Sacramento - San Joaquin River Delta of northern California (hereafter, the Delta) can help reverse the land subsidence that is currently threatening a large proportion of California's water supply. Wetland restoration maintains plant productivity while drastically reducing the rapid peat decomposition that has occurred since this region was drained for agricultural use in the 1850s. Rebuilding the peat soils i) protects California's water supply by reducing pressure on levies, and ii) mitigates globally rising atmospheric CO2 concentrations. The more anaerobic soil environment of wetlands, however, promotes methane (CH4) production, a 25x more potent greenhouse gas than CO2. It is therefore important to understand the impact of wetland restoration on both these gases to evaluate both subsidence reversal and climate change mitigation goals. To this end, we are conducting eddy covariance measurements of gas exchange in restored Delta wetlands to quantify ecosystem-scale sequestration/emission of CO2 and CH4. The ultimate goal of these measurements is to be able to predict the effects of wetland restoration on Delta-wide fluxes of these important greenhouse gases. Wetlands, however, are spatially variable ecosystems, varying in substrate, plant species, plant density, and open water fraction, to name a few. Extending site-level measurements to other areas therefore requires attributing spatial variability in CO2 and CH4 exchange to respective sources and identifying spatially available indicators of this change. This poster presents preliminary results evaluating the spatial variability of CO2 and CH4 fluxes in two restored Delta wetlands and how this variability can be up-scaled to region-wide estimates using remotely sensed indicators.

  19. Trace metal distribution in pristine permafrost-affected soils of the Lena River Delta and its Hinterland, Northern Siberia, Russia

    NASA Astrophysics Data System (ADS)

    Antcibor, I.; Zubrzycki, S.; Eschenbach, A.; Kutzbach, L.; Bol'shiyanov, D.; Pfeiffer, E.-M.

    2013-02-01

    Soils are an important compartment of ecosystems and have the ability to immobilize chemicals preventing their movement to other environment compartments. Predicted climatic changes together with other anthropogenic influences on Arctic terrestrial environments may affect biogeochemical processes enhancing leaching and migration of trace elements in permafrost-affected soils. This is especially important since the Arctic ecosystems are considered to be very sensitive to climatic changes as well as to chemical contamination. This study characterizes background levels of trace metals in permafrost-affected soils of the Lena River Delta and its hinterland in northern Siberia (73.5° N-69.5° N) representing a remote region far from evident anthropogenic trace metal sources. Investigations on total element contents of iron (Fe), arsenic (As), manganese (Mn), zinc (Zn), nickel (Ni), copper (Cu), lead (Pb), cadmium (Cd), cobalt (Co) and mercury (Hg) in different soil types developed in different geological parent materials have been carried out. The highest concentrations of the majority of the measured elements were observed in soils belonging to ice-rich permafrost sediments formed during the Pleistocene (ice-complex) in the Lena River Delta region. Correlation analyses of trace metal concentrations and soil chemical and physical properties at a Holocene estuarine terrace and two modern floodplain levels in the southern-central Lena River Delta (Samoylov Island) showed that the main factors controlling the trace metal distribution in these soils are organic matter content, soil texture and contents of iron and manganese-oxides. Principal Component Analysis (PCA) revealed that soil oxides play a significant role in trace metal distribution in both top and bottom horizons. Occurrence of organic matter contributes to Cd binding in top soils and Cu binding in bottom horizons. Observed ranges of the background concentrations of the majority of trace elements were similar to

  20. [Spectral data analysis of salinity soils with ground objects in the delta oasis of Weigan and Kuqa Rivers].

    PubMed

    Zhang, Fei; Ding, Jian-li; Tashpolat; Tiyip; He, Qi-sheng

    2008-12-01

    The characteristic of landmark spectrum is not only the physical base of remote sensing technical application but also the base of the quantificational analysis of remote sensing, and the study of landmark spectrum is the main content in the basic research of remote sensing. In the present paper, the authors adopted CI700 portable spectrum apparatus made in American CID Company, and investigated or examined some spots in the delta oasis of Weigan and Kuqa rivers located in the north of Tarim Basin considered as the typical area, based on a great deal of spectral data for different kinds of geo-targets, and the spectral features and changing law of saline-alkaline ground, silver sand ground, dune, cotton ground etc. Alhagi sparsifolia., Phragmites australis, Tamarix, Halostachys caspica etc. were analyzed. According to the actual conditions, we analyzed the data noise characteristic of the spectrum and got rid of the noise. Meanwhile, derivative spectrum technology was used to remove the environmental background influence. Finally, in order to take full advantage of multi-spectrum data, ground information is absolutely necessary, and it is important to build a representative spectral library. The ENVI software was used to build the spectral library of surface features by field survey of the delta oasis of Weigan and Kuqa Rivers, Xinjiang Uygur Autonomous Region. This library can be used for features investigation, vegetation surveys, vegetation classification and environmental monitoring in the delta oasis of Weigan and Kuqa Rivers by remote sensing. The result of this research will be significant to the research on the saline-alkali soil in the arid area.

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

    SciTech Connect

    Sather, NK; Johnson, GE; Storch, AJ

    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 River

  2. Evaluation of a floating fish guidance structure at a hydrodynamically complex river junction in the Sacramento–San Joaquin River Delta, California, USA

    USGS Publications Warehouse

    Romine, Jason G.; Perry, Russell W.; Pope, Adam C; Stumpner, Paul; Liedtke, Theresa L.; Kumagai, Kevin K; Reeves, Ryan L

    2016-01-01

    Survival of out-migrating juvenile Chinook salmon (Oncorhynchus tshawytscha) in the Sacramento–San Joaquin River delta, California, USA, varies by migration route. Survival of salmonids that enter the interior and southern Delta can be as low as half that of salmonids that remain in the main-stem Sacramento River. Reducing entrainment into the higher-mortality routes, such as Georgiana Slough, should increase overall survival. In spring 2014, a floating fish-guidance structure (FFGS) designed to reduce entrainment into Georgiana Slough was deployed just upstream of the Georgiana Slough divergence. We used acoustic telemetry to evaluate the effect of the FFGS on Chinook entrainment to Georgiana Slough. At intermediate discharge (200–400 m3 s–1), entrainment into Georgiana Slough was five percentage points lower when the FFGS was in the on state (19.1% on; 23.9% off). At higher discharge (>400 m3 s–1), entrainment was higher when the FFGS was in the on state (19.3% on; 9.7% off), and at lower discharge (0–200 m3 s–1) entrainment was lower when the FFGS was in the on state (43.7% on; 47.3% off). We found that discharge, cross-stream fish position, time of day, and proportion of flow remaining in the Sacramento River contributed to the probability of being entrained to Georgiana Slough.

  3. Clay mineralogy of contrasting mudflow and distal shelf deposits on the Mississippi River delta front

    NASA Astrophysics Data System (ADS)

    Roberts, Harry H.

    1985-09-01

    Mass movement processes are the most important transport agents on the modern delta front. Changes in relative abundances of kaolinite, illite, and smectite proved to be valuable descriptors for distinguishing mudflow deposits (derived from the shallow delta front) from outer shelf/upper slope sediments. Fine-grained sediments, rapidly deposited from the turbid distributary plumes in the upper delta front, are typically high in smectite relative to illite and kaolinite. Distal shelf and upper slope sediments display an increased abundance of kaolinite and illite at the expense of smectite. Shifts in abundances of clay minerals define the bases and internal stratigraphy of complex mudflows.

  4. Suspension of bed material over sand bars in the Lower Mississippi River and its implications for Mississippi delta environmental restoration

    NASA Astrophysics Data System (ADS)

    Ramirez, Michael T.; Allison, Mead A.

    2013-06-01

    specific pathways for sand transport in the lower reaches of large rivers, including the Mississippi, is a key for addressing multiple significant geologic problems, such as delta building and discharge to the oceans, and for environmental restoration efforts in deltaic environments threatened by rising sea levels. Field studies were performed in the Mississippi River 75-100 km upstream of the Gulf of Mexico outlet in 2010-2011 to examine sand transport phenomena in the tidally affected river channel over a range of discharges. Methods included mapping bottom morphology (multibeam sonar), cross-sectional and longitudinal measurements of water column velocity and acoustic backscatter, suspended sediment sampling, and channel-bed sampling. Substantial interaction was observed between the flow conditions in the river (boundary shear stress), channel-bed morphology (size and extent of sandy bedforms), and bed material sand transport (quantity, transport mode, and spatial distribution). A lateral shift was observed in the region of maximum bed material transport from deep to shallow areas of subaqueous sand bars with increasing water discharge. Bed material was transported both in traction and in suspension at these water discharges, and we posit that the downriver flux of sand grains is composed of both locally- and drainage basin-sourced material, with distinct transport pathways and relations to flow conditions. We provide suggestions for the optimal design and operation of planned river diversion projects.

  5. [Emission factors and PM chemical composition study of biomass burning in the Yangtze River Delta region].

    PubMed

    Tang, Xi-Bin; Huang, Cheng; Lou, Sheng-Rong; Qiao, Li-Ping; Wang, Hong-Li; Zhou, Min; Chen, Ming-hua; Chen, Chang-Hong; Wang, Qian; Li, Gui-Ling; Li, Li; Huang, Hai-Ying; Zhang, Gang-Feng

    2014-05-01

    The emission characteristics of five typical crops, including wheat straw, rice straw, oil rape straw, soybean straw and fuel wood, were investigated to explore the gas and particulates emission of typical biomass burning in Yangzi-River-Delta area. The straws were tested both by burning in stove and by burning in the farm with a self-developed measurement system as open burning sources. Both gas and fine particle pollutants were measured in this study as well as the chemical composition of fine particles. The results showed that the average emission factors of CO, NO, and PM2,5 in open farm burning were 28.7 g.kg -1, 1.2 g.kg-1 and 2.65 g kg-1 , respectively. Due to insufficient burning in the low oxygen level environment, the emission factors of stove burning were higher than those of open farm burning, which were 81.9 g kg-1, 2. 1 g.kg -1 and 8.5 gkg -1 , respectively. Oil rape straw had the highest emission factors in all tested straws samples. Carbonaceous matter, including organic carbon(OC) and element carbon(EC) , was the foremost component of PM2, 5from biomass burning. The average mass fractions of OC and EC were (38.92 +/- 13.93)% and (5.66 +/-1.54)% by open farm burning and (26.37 +/- 10. 14)% and (18.97 +/- 10.76)% by stove burning. Water soluble ions such as Cl-and K+ had a large contribution. The average mass fractions of CI- and K+ were (13.27 +/-6. 82)% and (12.41 +/- 3.02)% by open farm burning, and were (16.25 +/- 9.34)% and (13.62 +/- 7.91)% by stove burning. The K +/OC values of particles from wheat straw, rice straw, oil rape straw and soybean straw by open farm burning were 0. 30, 0. 52, 0. 49 and 0. 15, respectively, which can be used to evaluate the influence on the regional air quality in YRD area from biomass burning and provide direct evidence for source apportionment.

  6. [Distribution of Regional Pollution and the Characteristics of Vertical Wind Field in the Pearl River Delta].

    PubMed

    Liu, Jian; Wu, Dui; Fan, Shao-jia

    2015-11-01

    Based on the data of hourly PM2.5 concentration of 56 environmental monitoring stations and 9 cities over the Pearl River Delta (PRD) region, the distributions of PM2.5 pollution in PRD region were analyzed by systematic cluster analysis and correlational analysis. It was found that the regional pollution could be divided into 3 types. The first type was the pollution occurred in Dongguan, Guangzhou, Foshan and Jiangmen (I type), and the second type was the pollution occurred in Zhongshan, Zhuhai, Shenzhen and Huizhou (II type), while the last type was the pollution only occurred in Zhaoqing (III type). During the study period, they occurred 47, 7 and 128 days, respectively. During events of pollution type I, except Zhuhai, Shenzhen and Huizhou, the PM2.5 concentrations of other cities were generally high, while the PM2.5 concentration in whole PRD region was over 50.0 μg x m(-3) during events of pollution type II. The regions with higher PM2.5 concentration was mainly concentrated in Zhaoqing, Guangzhou and Foshan during events of pollution type III. The wind data from 4 wind profile radars located in PRD region was used to study the characteristics of vertical wind field of these 3 pollution types. It was found that the wind profiles of type I and III were similar that low layer and high layer were controlled by the southeast wind and the southwest wind, respectively. For type II, the low layer and high layer were influenced by northerly wind and westerly wind, respectively. Compared with other types, the wind speed and ventilation index of type II. were much higher, and the variation of wind direction at lower-middle-layer was much smaller. When PRD region was influenced by northerly winds, the PM2.5 concentration in the entire PRD region was higher. When PRD region was controlled by southeast wind, the PM2.5 concentrations of I and II areas were relatively lower, while the pollution in III area was relatively heavier.

  7. Growth of river delta networks: Thresholds, periodicity, aging and self similarity (Invited)

    NASA Astrophysics Data System (ADS)

    Jerolmack, D. J.; Reitz, M. D.

    2010-12-01

    The surfaces of river deltas and alluvial fans (collectively fans) are often dissected by a small number of channels radiating from the fan apex. These dispersive, depositional systems do not exhibit the fractal scaling typical of erosional drainage networks. On long timescales, fan channels migrate via avulsion - the process of channel bed deposition and abandonment. What governs the selection of new flow paths, or the ultimate number of active channels, is poorly understood. Here we present results of an experimental fan that allow us to examine the growth of a depositional channel network. Flow over the fan collapses into a single channel whose dimensions adjust to threshold transport conditions for the imposed sediment load. This channelization causes localized shoreline growth, which diminishes transport capacity of the channel until the slope drops below the threshold value. This leads to deposition within the channel and widespread flooding; avulsion is completed when a new channel path is selected. This cycle is remarkably periodic, and dynamics suggest that fan slope oscillates between two thresholds - entrainment and distrainment - analogous to static and dynamic angles of repose in grain flows. Selection of a new flow path is inherently stochastic, but previously abandoned channels act as significant attractors for the flow. In the early stages of fan growth, new channels are likely to be created. Once a critical density of flow paths has been established, however, the flow oscillates among the same 3-5 channels indefinitely. These dynamics are similar to the aging phenomenon observed in the growth of fractures in brittle materials under stress. We demonstrate that a directed random walk model with memory quantitatively reproduces these dynamics and limiting behavior, and is consistent with natural fans. Because our experimental fan is built by the recurring avulsion sequence, its shoreline shape is a series of lobes that indicate persistent upstream

  8. Land subsidence in the Yangtze River Delta, China revealed from multi-frequency SAR Interferometry

    NASA Astrophysics Data System (ADS)

    Li, Zhenhong; Motagh, Mahdi; Yu, Jun; Gong, Xulong; Wu, Jianqiang; Zhu, Yefei; Chen, Huogen; Zhang, Dengming; Xu, Yulin

    2014-05-01

    Land subsidence is a major worldwide hazard, and its principal causes are subsurface fluid withdrawal, drainage of organic soils, sinkholes, underground mining, hydrocompaction, thawing permafrost, and natural consolidation. Land subsidence causes many problems including: damage to public facilities such as bridges, roads, railroads, electric power lines, underground pipes; damage to private and public buildings; and in some cases of low-lying land, can increase the risk of coastal flooding from storm surges and rising sea-levels. In China, approximately 48600 km2 of land, an area roughly 30 times of the size of the Greater London, has subsided (nearly 50 cities across 16 provinces), and the annual direct economic loss is estimated to be more than RMB 100 million (~12 million). It is believed that the Suzhou-Wuxi-Changzhou region within the Yangtze River Delta is the most severely affected area for subsidence hazards in China. With its global coverage and all-weather imaging capability, Interferometric SAR (InSAR) is revolutionizing our ability to image the Earth's surface and the evolution of its shape over time. In this paper, an advanced InSAR time series technique, InSAR TS + AEM, has been employed to analysed ERS (C-band), Envisat (C-band) and TerraSAR-X (X-band) data collected over the Suzhou-Wuxi-Changzhou region during the period from 1992 to 2013. Validation with precise levelling and GPS data suggest: (1) the accuracy of the InSAR-derived mean velocity measurements is 1-3 mm/yr; (2) InSAR-derived displacements agreed with precise levelling with root mean square errors around 5 mm. It is evident that InSAR TS + AEM can be used to image the evolution of deformation patterns in the Suzhou-Wuxi-Changzhou region over time: the maximum mean velocity decreased from ~12 cm/yr during the period of 1992-1993 to ~2 cm/yr in 2003-2013. This is believed to be a result of the prohibition of groundwater use carried out by Jiangsu provincial government. The combination

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

    NASA Astrophysics Data System (ADS)

    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

  10. Mercury speciation and emission from municipal solid waste incinerators in the Pearl River Delta, South China.

    PubMed

    Chen, Laiguo; Liu, Ming; Fan, Ruifang; Ma, Shexia; Xu, Zhencheng; Ren, Mingzhong; He, Qiusheng

    2013-03-01

    The potential for Hg release during municipal solid waste incineration (MSWI) is attracting increased attention due to high volume of municipal waste being treated by incineration in China. Emission amounts have been estimated using emission factors developed for other countries. To fine tune our emission estimate total mercury (THg) and mercury speciation were measured using isokinetic sampling in eight plants, of which six used grate furnace combustor (GFC) and two circulation fluidized bed combustors (CFBCs). Results showed that average THg concentration (19.5 ± 13.6 μg/Nm) in flue gas at the facilities that used CFBC was significantly lower than that at those using GFC (51.4 ± 28.3 μg/Nm, p=0.002). Gaseous oxidized mercury (GOM), gaseous elemental mercury (GEM, Hg), and particulate mercury (Hg) represented 95.5 ± 3.8%, 4.1 ± 3.9% and 0.4 ± 0.3% in GFC, and 63.8 ± 8.6%, 33.6 ± 10.5% and 2.6 ± 1.9% in CFBC, respectively. The measured average THg emission factor for the 8 MSWI plants was 208 ± 130 mg/t in the Pearl River Delta (PRD) region, with 217 ± 158 mg/t and 188 ± 17.7 mg/t were from GFC and CFBC, respectively. Using the average emission factor the estimated total mercury emissions from MSWI were 4.67 ± 2.91 t in China, and 770 ± 65.5 kg in the PRD region in 2010. Of these, 4240 ± 210 kg, 408 ± 231 kg and 14.8 ± 14.1 kg, and 688 ± 37 kg, 78.9 ± 40.6 kg and 3.2 ± 3.0 kg were GOM, Hg, and Hg, respectively. Mercury emissions will continue to increase as the amounts of MSW being incinerated increases. PMID:23410861

  11. Renesting by dusky Canada geese on the Copper River Delta, Alaska

    USGS Publications Warehouse

    Fondell, Thomas F.; Grand, James B.; Miller, David A.W.; Anthony, R. Michael

    2006-01-01

    The population of dusky Canada geese (Branta canadensis occidentalis; hereafter duskies) breeding on the Copper River Delta (CRD), Alaska, USA, has been in long-term decline, largely as a result of reduced productivity. Estimates of renesting rates by duskies may be useful for adjusting estimates of the size of the breeding population derived from aerial surveys and for understanding population dynamics. We used a marked population of dusky females to obtain estimates of renesting propensity and renesting interval on the CRD, 1999–2000. Continuation nests, replacement nests initiated without a break in the laying sequence, resulted only after first nests were destroyed in the laying stage with ≤4 eggs laid. Renesting propensity declined with nest age from 72% in mid-laying to 30% in early incubation. Between first nests and renests, mean interval was 11.9 ± 0.6 days, mean distance was 74.5 m (range 0–214 m), and clutch size declined 0.9 ± 0.4 eggs. We incorporated our renesting estimates and available estimates of other nesting parameters into an individual-based model to predict the proportion of first nests, continuation nests, and renests, and to examine female success on the CRD, 1997–2000. Our model predicted that 19–36% of nests each year were continuation nests and renests. Also, through 15 May (the approx. date of breeding ground surveys), 1.1–1.3 nests were initiated per female. Thus, the number of nests per female would have a significant, though relatively consistent, effect on adjusting the relation between numbers of nests found on ground surveys versus numbers of birds seen during aerial surveys. We also suggest a method that managers could use to predict nests per female using nest success of early nests. Our model predicted that relative to observed estimates of nest success, female success was 32–100% greater, due to replacement nests. Thus, although nest success remains low, production for duskies was higher than previously thought

  12. Non-methane hydrocarbon characteristics of motor vehicular emissions in the Pearl River Delta region

    NASA Astrophysics Data System (ADS)

    Tsai, Wai Yan

    2007-12-01

    Air pollution problem in Hong Kong and the Pearl River Delta (PRD) region has raised much concern from the public in recent years. The primary aim of this research is to use field measurement data to characterize non-methane hydrocarbons (NMHCs) in emission from motor vehicles. Fuel vapor compositions for several commonly used vehicular fuels in Hong Kong, Macau, Guangzhou and Zhuhai were analyzed in 2003, and they are believed to be the first one reported for the PRD region. These profiles were used to study the impact of evaporative loss of the fuels on air quality. From the roadside and tunnel samples collected in the four cities mentioned above from 2000 to 2003, results showed that vehicular engine combustion was a main NMHC source, while gasoline evaporative losses also contributed much to the total NMHC emission, besides, LPG leakage was also found to be significant from the tunnel measurement data collected in Hong Kong. Characteristics of vehicular engine exhaust emissions were also studied. Measurements of diesel emission showed a large influence on the emission profile due to the change of diesel compositions. The E/E ratios implied that gasoline-powered vehicles in Hong Kong were equipped with well functioning catalysts, while those in Guangzhou and Zhuhai, especially the motorcycles, were found dirtier in NMHC emission. Although the E/E ratios showed that private cars in Hong Kong had high combustion efficiency, the existence of significant amounts of unburned gasoline in their exhaust stream pointed out that they still had low fuel economy. From the results of a simple model, it was found that the evaporative losses of gasoline and LPG contributed much to the total NMHC pollution from vehicle. The preliminary results from the dynamometer study conducted in Hong Kong showed large variations of exhaust characteristics for private cars and taxis during different driving speeds. The results can be used as scientific basis for regulatory parties in

  13. Prevalence and characterization of Cryptosporidium spp. in dairy cattle in Nile River delta provinces, Egypt.

    PubMed

    Amer, Said; Zidan, Shereif; Adamu, Haileeyesus; Ye, Jianbin; Roellig, Dawn; Xiao, Lihua; Feng, Yaoyu

    2013-11-01

    Molecular characterizations of Cryptosporidium spp. in dairy cattle in industrialized nations have mostly shown a dominance of Cryptosporidium parvum, especially its IIa subtypes in pre-weaned calves. Few studies, however, have been conducted on the distribution of Cryptosporidium species and C. parvum subtypes in various age groups of dairy cattle in developing countries. In this study, we examined the prevalence and molecular characteristics of Cryptosporidium in dairy cattle in four Nile River delta provinces in Egypt. Modified Ziehl-Neelsen acid-fast microscopy was used to screen for Cryptosporidium oocysts in 1974 fecal specimens from animals of different ages on 12 farms. Positive fecal specimens were identified from all studied farms with an overall prevalence of 13.6%. By age group, the infection rates were 12.5% in pre-weaned calves, 10.4% in post-weaned calves, 22.1% in heifers, and 10.7% in adults. PCR-RFLP and DNA sequence analyses of microscopy-positive fecal specimens revealed the presence of four major Cryptosporidium species. In pre-weaned calves, C. parvum was most common (30/69 or 43.5%), but Cryptosporidium ryanae (13/69 or 18.8%), Cryptosporidium bovis (7/69 or 10.2%), and Cryptosporidium andersoni (7/69 or 10.2%) were also present at much higher frequencies seen in most industrialized nations. Mixed infections were seen in 12/69 (17.4%) of genotyped specimens. In