Seed dispersal by wintering ducks in a coastal wetland of eastern China

Duck species are important vectors for seed dispersal of many plants,contributing significantly to the regeneration of wetland plant communities.However,research on the temporal changes in diet and the dynamics and differences of seed dispersal among different duck species is still limited.In this study,we analyzed the diversity of duck community and the diversity of seeds in the feces of different duck species from December to February for 2022–23 and 2023–24 in the coastal wetland of Dafeng,eastern Jiangsu Province,China.A total of 13 duck species were recorded in the four habitats,of which Spot-billed Ducks(Anas zonorhyncha)and Mallards(A.platyrhynchos)were the most abundant.The diversity and abundance of ducks vary across different habitats,and tidal flat supports the greatest diversity and abundance of ducks.We collected fecal samples from Spot-billed Ducks,Gadwalls(Mareca strepera),Mallards,and Eurasian Teals(A.crecca)in the tidal flat,from which seeds belonging to 7 families,13 genera and 15 different plant species were obtained.There were significant differences in seed dispersal among the four duck species,which varied with the season.Gadwalls and Common Teals showed more significant diversity in seed dispersal,with their feces containing a greater variety of plant seeds,which is related to their broader dietary range and ecological adaptability.Furthermore,the seasonal variation in the number of seeds per feces reflected the availability of seeds in the habitat and the response of ducks to environmental changes,while variations in seed intake among different duck species may be associated with inter-annual weather condition changes.The results of this study will provide a new perspective for understanding the mechanisms of bird-mediated seed dispersal in coastal wetland and offer preliminary insights for the seed dispersal by Asian ducks.

Effects of Vegetation Restoration Age on Soil C:N:P Stoichiometry in Yellow River Delta Coastal Wetland of China

Vegetation restoration can alter carbon(C),nitrogen(N),and phosphorus(P)cycles in coastal wetlands affecting C:N:P stoichiometry.However,the effects of restoration age on soil C:N:P stoichiometry are unclear.In this study,we examined the re-sponses of soil C,N,and P contents and their stoichiometric ratios to vegetation restoration age,focusing on below-ground processes and their relationships to aboveground vegetation community characteristics.We conducted an analysis of temporal gradients based on the'space for time'method to synthesize the effects of restoration age on soil C:N:P stoichiometry in the Yellow River Delta wetland of China.The findings suggest that the combined effects of restoration age and soil depth create complex patterns of shifting soil C:N:P stoichiometry.Specifically,restoration age significantly increased all topsoil C:N:P stoichiometries,except for soil total phosphorus(TP)and the C:N ratio,and slightly affected subsoil C:N:P stoichiometry.The effects of restoration age on the soil C:N ratio was well constrained owing to the coupled relationship between soil organic carbon(SOC)and total nitrogen(TN)contents,while soil TP con-tent was closely related to changes in plant species diversity.Importantly,we found that the topsoil C:N:P stoichiometry was signific-antly affected by plant species diversity,whereas the subsoil C:N:P stoichiometry was more easily regulated by pH and electric con-ductivity(EC).Overall,this study shows that vegetation restoration age elevated SOC and N contents and alleviated N limitation,which is useful for further assessing soil C:N:P stoichiometry in coastal restoration wetlands.

Seasonal response of nitrogen exchange fluxes to crab disturbance at sediment-water interface in coastal tidal wetlands

Coastal wetlands are hotspots for nitrogen(N)cycling,and crab burrowing is known to transform N in intertidal marsh soils.However,the underlying mechanisms remain unclear.This study conducted field experiments and used indoor control test devices to investigate the seasonal response of nitrogen to crab disturbance at the sediment-water interface in coastal tidal flat wetlands.The results showed that crab disturbance exhibited significant seasonality with large seasonal differences in cave density and depth.Due to crab disturbance,nitrogen fuxes at the sediment-water interface were much greater in the box with crabs than in the box without crabs.In summer,NH-N showed a positive flux from the sediment to the overlying water,but NO2-N and NOg-N showed positive fluxes from the sediment to the overlying water only in early stages.In winter,NH-N showed a positive flux from the sediment to the overlying water,but NO-N and NO,-N both exhibited positive and negative fluxes.These results indicated that the presence of crab burrows can cause the aerobic layer to move downward by approximately 8-15 cm in summer and directly promote nitrification at the sediment surface.

Changes of Wetland Landscape Pattern in New Coastal District of Tianjin City

With the wetland landscape in New Coastal District of Tianjin City as the chief study objective and based on the remote sensing and non-remote sensing data of ETM/TM with 1999-2007 as the time scale and the new administrative region of New Coastal District as the space (scale) scope, this paper conducted the study on the landscape pattern change. The results showed that the natural wetland and agricultural land tended to decrease, while the saltern, maricultural areas and construction land increased apparently. The overall landscape shape tended to develop in simplification and regulation and with the development of population and social economy, human’s intervention to the landscape was getting improved.

Spatial distribution of heavy metals(Cu, Pb, Zn, and Cd)in sediments of a coastal wetlands in eastern Fujian, China

We investigated the spatial distribution （horizontal and vertical concentrations） of copper （Cu）, lead （Pb）, zinc （Zn）, and cadmium （Cd） in five wetland types （mudflat, aquaculture wetland, water area, farmland wetland and mangrove） from three areas （Ningde, Fuding, and Xiapu）, China. Cu concentrations in five wetland types descended in the order： farm wetland, mudflat, aquaculture, water area and mangrove. Pb concentrations decreased in the order： aquaculture, mangrove, farm wetland, mudflat, and water area. Zn content decreased in the order： farm wetland, water area, aquaculture, mudflat and mangrove, and Cd content decreased as follows： mangrove, aquacul- ture, water area, rnudflat, and farm wetland. Comparison of the concentrations of the same heavy metals in different areas showed that the highest Cu （63.75 mg kg-1） and Zn （152.32mgkg-1） concentrations occurred in Ningdecoastal wetlands; Pb （110.58 mg kg-1） and Cd （2.81 mg kg-1） contents were highest in Fuding wetlands, and the average contents of all heavy metals were very low in Xiapu wetlands. Examination of the vertical distribution showed that the Cu content was high in all mudflat layers; Pb and Cd concentrations were highest in aquaculture and mangrove wetlands, respectively, and Zn content was highest in farm wetlands. The spatial distribution of Cu and Zn contents for different areas decreased as follows： Ningde 〉 Fuding 〉 Xiapu, for Pb and Cd were most concentrated in Fuding coastal wetlands. Concentrations of Zn and Cu were highly correlated, while Zn and Cu were not significantly correlated with Pb.

Identification of coastal wetlands of international importance for waterbirds:a review of China Coastal Waterbird Surveys 2005–2013

Background:China's coastal wetlands belong to some of the most threatened ecosystems worldwide.The loss and degradation of these wetlands seriously threaten waterbirds that depend on wetlands.Methods:The China Coastal Waterbird Census was organized by volunteer birdwatchers in China's coastal region.Waterbirds were surveyed synchronously once every month at 14 sites,as well as irregularly at a further 18 sites,between September 2005 and December 2013.Results:A total of 75 species of waterbirds met the 1 % population level Ramsar listing criterion at least once at one site.The number of birds of the following species accounted for over 20 % of the total flyway populations at a single site:Mute Swan(Cygnus olor),Siberia Crane(Grus leucogeranus),Far Eastern Oystercatcher(Haematopus osculans),Bar-tailed Godwit(Limosa lapponica),Spotted Greenshank(Tringa guttifer),Great Knot(Calidris tenuirostris),Spoon-billed Sandpiper(Calidris pygmeus),Saunders' s Gull(Larus saundersi),Relict Gull(Larus relictus),Great Cormorant(Phalacrocorax carbo),Eurasian Spoonbill(Platalea leucorodia),Black-faced Spoonbill(Platalea minor) and Dalmatian Pelican(Pelecanus crispus).A total of 26 sites supported at least one species of which their number met the1 % criterion.Forty-two species met the 1 % criterion in the Yellow River Delta,Shandong;29 at the Cangzhou coast,Hebei and 26 species at the Lianyungang coast,Jiangsu.Conclusions:The results highlight the international importance of China's coastal wetlands for waterbirds.This study also demonstrates that participation of local birdwatchers in waterbird surveys results in data that are invaluable not only for understanding the current status of waterbirds in China's coastal regions but also for waterbird conservation and management.

Comparison of Carbon, Nitrogen, and Sulfur in Coastal Wetlands Dominated by Native and Invasive Plants in the Yancheng National Nature Reserve, China

The rapid invasion of the plant Spartina alterniflora in coastal wetland areas can threaten the capacity of their soils to store carbon(C),nitrogen(N),and sulfur(S).In this study,we investigated the spatial and temporal distribution patterns of C,N and S of both soil and(native and invasive)plants in four typical coastal wetlands in the core area of the Yancheng National Nature Reserve,China.The results show that the invasive S.alterniflora greatly influenced soil properties and increased soil C,N and S storage capacity:the stock(mean±standard error)of soil organic carbon(SOC,(3.56±0.36)kg/m^3),total nitrogen(TN,(0.43±0.02)kg/m^3),and total sulfur(TS,(0.69±0.11)kg/m^3)in the S.alterniflora marsh exceeded those in the adjacent bare mudflat,Suaeda salsa marsh,and Phragmites australis marsh.Because of its greater biomass,plant C((1193.7±133.6)g/m^2),N((18.8±2.4)g/m^2),and S((9.4±1.5)g/m^2)storage of S.alterniflora was also larger than those of co-occurring native plants.More biogenic elements circulated in the soil-plant system of the S.alterniflora marsh,and their spatial and temporal distribution patterns were also changed by the S.alterniflora invasion.Soil properties changed by S.alterniflora’s invasion thereby indirectly affected the accumulation of soil C,N and S in this wetland ecosystem.The SOC,TN,and TS contents were positively correlated with soil electrical conductivity and moisture,but negatively correlated with the pH and bulk density of soil.Together,these results indicate that S.alterniflora invasion altered ecosystem processes,resulted in changes in net primary production and litter decomposition,and increased the soil C,N and S storage capacity in the invaded ecosystems in comparison to those with native tallgrass communities in the coastal wetlands of East China.

Spatial Variations in Depth-distribution of Trace Metals in Coastal Wetland Sediments from Quanzhou Bay,Fujian Province,China

Four short cores were obtained from the coastal wetland of the Quanzhou Bay,Fujian Province,China,and sediment samples were analyzed with a Mastersizer 2000 for grain size analysis and an Inductively Coupled Plasma Atomic Emission Spectrometer(ICP-AES) for trace metal analysis. The results of grain size analysis show that the wetland sediments are mainly composed of silt and clay,and the distribution of median grain size is affected by human activities obviously. The results of trace metal analysis show that the wetland sediments mainly originate from terrestrial materials in the Luoyangjiang River estuary and from contaminants discharged from adjacent rivers in Shuitou area. The heavy metal contamination in Luoyangjiang estuary decreased from 1984 to 2004 due to industry transformation,but has increased since 2004 because of the discharge of contaminants to the Jinjiang River and much living sewerage to the bay,and a large number of trace metals are trapped within Spartina alterniflora marsh.

Deep learning classification of coastal wetland hyperspectral image combined spectra and texture features: A case study of Huanghe(Yellow) River Estuary wetland

This paper develops a deep learning classification method with fully-connected 8-layers characteristics to classification of coastal wetland based on CHRIS hyperspectral image. The method combined spectral feature and multi-spatial texture feature information has been applied in the Huanghe(Yellow) River Estuary coastal wetland.The results show that:(1) Based on testing samples, the DCNN model combined spectral feature and texture feature after K-L transformation appear high classification accuracy, which is up to 99%.(2) The accuracy by using spectral feature with all the texture feature is lower than that using spectral only and combing spectral and texture feature after K-L transformation. The DCNN classification accuracy using spectral feature and texture feature after K-L transformation was up to 99.38%, and the outperformed that of all the texture feature by 4.15%.(3) The classification accuracy of the DCNN method achieves better performance than other methods based on the whole validation image, with an overall accuracy of 84.64% and the Kappa coefficient of 0.80.(4) The developed DCNN model classification algorithm ensured the accuracy of all types is more balanced, and it also greatly improved the accuracy of tidal flat and farmland, while kept the classification accuracy of main types almost invariant compared to the shallow algorithms. The classification accuracy of tidal flat and farmland is up to 79.26% and 56.72%respectively based on the DCNN model. And it improves by about 2.51% and 10.6% compared with that of the other shallow classification methods.

Impacts of Coastal Reclamation on Natural Wetlands in Large River Deltas in China

Little information is available on the impacts of coastal reclamation on wetland loss in large-river deltas at a regional scale.Using remote sensing data of coastal wetland and reclamation in four deltas in China from 1978 to 2014, we tracked their continuous area changes in four periods: 1978–1990, 1990–2000, 2000–2008, and 2008–2014. The areal relation between wetland loss and reclamation was quantified and used to identify coastal reclamation mode intensity coupled with another three indicators: reclamation rate,accretion rate and land-use intensity of coastal reclamation. The results showed that coastal reclamation driven by economic development reduced, or even reverse the original growth of delta which was determined by the offset between wetland acceleration rate and wetland loss rate. Generally, the area of reclamation showed a positive linear correlation with the area of wetland loss. The findings imply that human activities should control reclamation rate and intensity to alleviate total wetland loss and maintain wetland ’net gain’.Inappropriate coastal reclamation modes can magnify total wetland loss;therefore, coastal reclamation with a slow increment rate and low impervious surface percent is of great importance for sustainable development in future coastal management.

Ecological Offsetting in China's Coastal Wetlands: Existing Challenges and Strategies for Future Improvement

Land-use changes in coastal wetlands have led to a worldwide degradation of marine coastal ecosystems and a loss of the ecological services they provide. Ecological offsetting is a popular strategy and an effective mitigation measure for ecosystems that have been degraded, damaged, or destroyed and is critical for habitats where natural recovery is hindered. However, the current understanding of the theory and practice of ecological offsetting for coastal wetlands is extremely limited in many developing countries. We conducted a review of ecological offsetting for coastal wetlands projects and studies in China in 1979–2017 to explore the application and limitations of ecological offsetting theory. It was found that China's coastal ecological offsetting regime has recently entered a rapidly developing stage, with an increasing number of different types of offsetting projects conducted, but theoretical research lags behind practical applications. Considerable governmental, social, technological and ethical challenges remain to resolve. Coastal ecological offsetting schemes have been inconsistent in meeting conservation objectives or preventing net losses because of the challenges of ensuring they are fully consistent in practice(mainly in-kind offsets) and theory(mainly out-of-kind offsets). Ecological offsetting projects were primarily implemented by government, developers, and non-profit organizations. The available funding of coastal ecological offsetting projects is insufficient, which makes ecological offsetting a risky operation. Therefore, we propose strategies for improvement that integrate the consideration of theoretical and practical challenges in the offsetting process, while providing a scientific basis and directional guidance for the future practice of biodiversity conservation and environmental management.

Combined influence of sedimentation and vegetation on the soil carbon stocks of a coastal wetland in the Changjiang estuary

Coastal wetlands play an important role in the global carbon cycle. Large quantities of sediment deposited in the Changjiang （Yangtze） estuary by the Changjiang River promote the propagation of coastal wetlands, the expansion of saltmarsh vegetation, and carbon sequestration. In this study, using the Chongming Dongtan Wetland in the Changjiang estuary as the study area, the spatial and temporal distribution of soil organic carbon （SOC） stocks and the influences of sedimentation and vegetation on the SOC stocks of the coastal wetland were examined in 2013. There was sediment accretion in the northern and middle areas of the wetland and in the Phragmites australis marsh in the southern area, and sediment erosion in the Scirpus mariqueter marsh and the bare mudflat in the southem area. More SOC accumulated in sediments of the vegetated marsh than in the bare mudflat. The total organic carbon （TOC） stocks increased in the above-ground biomass from spring to autumn and decreased in winter; in the below-ground biomass, they gradually increased from spring to winter. The TOC stocks were higher in the below-ground biomass than in the above-ground biomass in the P. australis and Spartina alterniflora marshes, but were lower in the below-ground biomass in S. mariqueter marsh. Stocks of SOC showed temporal variation and increased gradually in all transects from spring to winter. The SOC stocks tended to decrease from the high marsh down to the bare mudflat along the three transects in the order： P. australis marsh 〉 S. alterniflora marsh 〉 S. mariqueter marsh 〉 bare mudflat. The SOC stocks of the same vegetation type were higher in the northern and middle transects than in the southern transect. These results suggest that interactions between sedimentation and vegetation regulate the SOC stocks in the coastal wetland in the Changjiang estuary.

Spatiotemporal Dynamics of Coastal Wetlands and Reclamation in the Yangtze Estuary During Past 50 Years(1960s–2015)

Reclamation is one of the fastest-growing land use type developed in coastal areas and has caused degradation and loss of coastal wetlands as well as serious environmental problems. This paper was aimed at monitoring the spatiotemporal patterns of coastal wetlands and reclamation in the Yangtze Estuary during the 1960s and 2015. Satellite images obtained from 1980 to 2015 and topography maps of the 1960 s were employed to extract changes of reclamation and coastal wetlands. Area-weight centroids were calculated to identify the movement trend of reclamation and coastal wetlands. The results show that from the 1960 s to 2015, the net area of natural wetlands declined by 574.3 km^2, while man-made wetlands and reclamation increased by 553.6 and 543.9 km^2, respectively. During the five study phases, the fastest areal change rate natural wetlands was –13.3 km^2/yr in the period of 1990–2000, and that of man-made areas was 24.7 km^2/yr in the same period, and the areal change rate of reclamation was 27.6 km^2/yr in the period of 2000–2010. Conversion of coastal wetlands mainly occurred in the Chongming Island, Changshu City and the east coast of Shanghai Municipality. Reclamation was common across coastal areas, and was mainly attributed to settlement and man-made wetlands in the Chongming Island, Lianyungang City and the east coast of Shanghai Municipality. Natural wetlands turned into farmlands and settlement, and man-made wetlands gained from reclamation of farmlands. The centroid of natural wetlands generally moved towards the sea, man-made wetlands expanded equally in all directions and inland, and the centroid of reclamation migrated toward Shanghai Municipality. Sea level rise, erosion-deposition changes, and reclamation activities together determine the dynamics of the Yangtze Estuary wetlands. However, reclamation activities for construction of ports, industries and aquaculture are the key causes for the dynamics. The results from this study on the dynamics of coastal wetlands and reclamation are valuable for local government to put forward sustainable land use and land development plans.

Validation of Global Evapotranspiration Product(MOD16) Using Flux Tower Data from Panjin Coastal Wetland,Northeast China

Recent advances in remote sensing technology and methods have resulted in the development of an evapotranspiration(ET) product from the Moderate Resolution Imaging Spectrometer(MOD16). The accuracy of this product however has not been tested for coastal wetland ecosystems. The objective of this study therefore is to validate the MOD16 ET product using data from one eddy covariance flux tower situated in the Panjin coastal wetland ecosystem within the Liaohe River Delta, Northeast China. Cumulative ET data over an eight-day period in 2005 from the flux tower was calculated to coincide with the MOD16 products across the same period. Results showed that data from the flux tower were inconsistent with that gained form the MOD16 ET. In general, results from Panjin showed that there was an underestimation of MOD16 ET in the spring and fall, with Biases of -2.27 and -3.53 mm/8 d, respectively(–40.58% and -49.13% of the observed mean). Results for Bias during the summer had a range of 1.77 mm/8 d(7.82% of the observed mean), indicating an overestimation of MOD16 ET. According to the RMSE, summer(6.14 mm/8 d) achieved the lowest value, indicating low accuracy of the MOD16 ET product. However, RMSE(2.09 mm/8 d) in spring was the same as that in the fall. Relationship between ET and its relevant meteorological parameters were analyzed. Results indicated a very good relationship between surface air temperature and ET. Meanwhile a significant relationship between wind speed and ET also existed. The inconsistent comparison of MOD16 and flux tower-based ET are mainly attributed to the parameterization of the Penman-Monteith model, flux tower measurement errors, and flux tower footprint vs. MODIS pixels.

Changes of Coastal Wetland Ecosystems in the Yellow River Delta and Protection Countermeasures to Them

Coastal wetlands in the Yellow River Delta are typical new wetland ecosystems in warm temperate zone. In recent years, influenced by natural and human factors, these coastal wetlands in the Yellow River Delta have undergone changes of landscape fragmentation, vegetation degradation, pollution, species reduction, and harmful exotic species invasion. These changes have influenced sustainable and healthy development of marine economy of the Yellow River Delta. To protect natural ecological environment of the Yellow River Delta, the authors recommended that it should establish and improve policies, laws and regulations of wetland protection; carry out wetland resource investigation and assessment and monitoring; strengthen comprehensive protection and control of wetland; reduce wetland degradation and promote sustainable use of wetland.

Effects of Reclamation on Soil Carbon and Nitrogen in Coastal Wetlands of Liaohe River Delta,China

To evaluate the influence of wetland reclamation on vertical distribution of carbon and nitrogen in coastal wetland soils, we measured the soil organic carbon(SOC), soil total nitrogen(STN) and selected soil properties at five sampling plots(reed marsh, paddy field, corn field, forest land and oil-polluted wetland) in the Liaohe River estuary in September 2013. The results showed that reclamation significantly changed the contents of SOC and STN in the Liaohe River estuary(P < 0.001). The SOC concentrations were in the order: oil-polluted wetland > corn field > paddy field > forest land > reed marsh, with mean values of 52.17, 13.14, 11.46, 6.44 and 6.16 g/kg, respectively. STN followed a similar order as SOC, with mean values of 1351.14, 741.04, 632.32, 496.17 and 390.90 mg/kg, respectively. Interaction of reclamation types and soil depth had significant effects on SOC and STN, while soil depth had significant effects on SOC, but not on STN. The contents of SOC and STN were negatively correlated with pH and redox potential(Eh) in reed marsh and corn field, while the SOC and STN in paddy field had positive correlations with electrical conductivity(EC). Dissolved organic carbon(DOC), ammonium nitrogen(NH_4^+-N) and nitrate nitrogen(NO_3~–-N) were also significantly changed by human activities. NH_4^+-N and NO_3~–-N increased to different degrees, and forest land had the highest NO_3~–-N concentration and lowest DOC concentration, which could have been caused by differences in soil aeration and fertilization. Overall, the results indicate that reed harvest increased soil carbon and nitrogen release in the Liaohe River Estuary, while oil pollution significantly increased the SOC and STN; however, these cannot be used as indicators of soil fertility and quality because of the serious oil pollution.

Effects of Anthropogenic Disturbance on Sediment Organic Carbon Mineralization Under Different Water Conditions in Coastal Wetland of a Subtropical Estuary

The changes in soil organic carbon(C) mineralization as affected by anthropogenic disturbance directly determine the role of soils as C source or sink in the global C budget. The objectives of this study were to investigate the effects of anthropogenic disturbance(aquaculture pond, pollutant discharge and agricultural activity) on soil organic C mineralization under different water conditions in the Minjiang River estuary wetland, Southeast China. The results showed that the organic C mineralization in the wetland soils was significantly affected by human disturbance and water conditions(P < 0.001), and the interaction between human disturbance activities and water conditions was also significant(P < 0.01). The C mineralization rate and the cumulative mineralized carbon dioxide-carbon(CO_2-C)(at the 49th day) ranked from highest to lowest as follows: Phragmites australis wetland soil > aquaculture pond sediment > soil near the discharge outlet > rice paddy soil. This indicated that human disturbance inhibited the mineralization of C in soils of the Minjiang River estuary wetland, and the inhibition increased with the intensity of human disturbance. The data for cumulative mineralized CO_2-C showed a good fit(R^2 > 0.91) to the first-order kinetic model C_t = C_0(1 – exp(–kt)). The kinetic parameters C_0, k and C_0 k were significantly affected by human disturbance and water conditions. In addition, the total amount of mineralized C(in 49 d) was positively related to C_0, C_0 k and electrical conductivity of soils. These findings indicated that anthropogenic disturbance suppressed the organic C mineralization potential in subtropical coastal wetland soils, and changes of water pattern as affected by human activities in the future would have a strong influence on C cycling in the subtropical estuarine wetlands.

Investigation on Water Pollution of Four Rivers in Coastal Wetland of Yellow River Estuary

[Objective] The study aimed at analysing water pollution of four rivers in coastal wetland of Yellow River estuary. [Method] Taking four seriously polluted rivers (Guangli River, Shenxian Ditch, Tiao River and Chao River) in coastal wetland of Yellow River estuary as study objects, water samples were collected from the four rivers in May (dry period), August (wet period) and November (normal period) in 2009 and 2010 respectively, then pollution indices like nutritive salts, COD, chlorophyll-a, petroleum, etc. were measured. Afterwards, the status quo of water pollution was assessed based on Nemero index and comprehensive trophic level index (TLI), so as to find out the integral status quo of water quality of wetland rivers and damages to aquatic ecological environment. [Result] On the whole, water pollution of four rivers in coastal wetland of Yellow River estuary was serious, in the eutrophication state, and the main pollutants were TN, TP, NH+4-N and petroleum. In addition, excessive N and P in the four rivers resulted in water eutrophication of Bohai Bay, so further leading to ride tide, which destroyed the coastal ecological environment of Bohai Sea. Moreover, compared with historical data, water pollution by nitrogen and phosphorus became more serious, while there was no obvious aggravation in the water pollution by petroleum. In a word, water pollution wasn’t optimistic on the whole. [Conclusion] The research could provide theoretical bases for the protection and utilization of river water in coastal wetland of Yellow River estuary and its coastal sea area.

Phosphorus Behavior at Sediment-Water Interface in Coastal Wetland

[Objective] The aim was to explore the role of coastal wetlands in phosphorus fixation in the Yellow River Delta.[Method] The research analyzed phosphorus behavior at sediment-water interface by static water column test. [Result] The research concluded that phosphorus concentration was in the range of 0.051-0.322 mg/L in overlying water, and phosphorus was effectively removed by degradation and adsorption. The static water column test has demonstrated that phosphorus concentration of coastal wetlands plays the role of accumulation when phosphorus concentration is lower than 7 mg/L in overlying water of coastal wetlands. It is notable that substrates of overlying water all perform well in adsorption, and the adsorption reaches saturation if the concentration goes up to 10 mg/L. [Conclusion] Coastal wetlands would significantly adsorb and degrade phosphorus in overlying water, controlling phosphorus within a lower range.