PRIMARY FISH SURVEY IK THE HUANGHE RIVER ESTUARY

The survey in the, Huanghe River estuary indicated that the 85 fish species found there comprised three faunal elements: warm-water species (29.4%), warm-temperate species (55.3%) and cpld-temperate species. (15.3%). The seasonal changes of fish species, density and bipmass are obvious. The total biomass is highest (7699t) in August and lowest(489 t) in January. Setipinna taty has mean density of 9278 indiv/km2, and is the most important species constituting 25.5% of the total weight of fish caught. Trichiurus haumela was a dominant species in the 1950s, but no one was caught in this survey. There were obvious changes of the dominant fish species during the recent three decades. The demersal fish biomass has dropped greatly to only 1/10 in over 50 years since 1930.     

Densities of Huanghe River estuary and Bohai Bay waters

The densities of 36 water samples from the Huanghe River estuary and Bohai Bay were determinedby a magnetic float densimcter under three temperatures from 15℃ to 25℃.All the measured densities ofsamples were greater than that of the values calculated from the International Equation of State of Seawater.The differences between the measured and calculated densities increased with the decrease of salinities.The dif-ferences appeared exponentially correlated with[Ca~(2+)]/s,[Mg~(2+)]/s and[SO_4~(2-)]/s,and had"s"type curverelationship with the alkalinity in all salinity range.But in the salinity ranging from 25.72 to 31.57,therelationships were all linear.The density difference can be estimated from the equation △ρ（10~3kg·m~(-3)）=（-2.79+236.5([Ca~(2+)]/s)/(-9.7464×10~（-3）+[Ca~(2+)]/s).It was the high alkalinity and[Ca~(2+)]/s that resulted in the measured densi-ties of seawaters being higher than the calculated densities in the Huanghe estuary and Bohai Bay.     

MODERN SEDIMENTATION RATES AND SEDIMENTATION FEATURE IN THE HUANGHE RIVER ESTUARY BASED ON ~(210)Pb TECHNIQUE

Based on Pb technique, sedimentation rates of 11 cores collected from the Huanghe River estuary were determined. CaCO3 distribution of 4 cores chosen from among these was measured. Profiles of 210Pb in the cores showed that the distribution of 210Pb activity decayed with depth, appeared in stages and in more than one segment. The sedimentation rates,210Pb and CaCO3 data have similar distribution trend in the 4 cores. Jhe profiles of Pb and CaCO3 were used to study sedimentation in -tensity, transportation trend of material and sedimentation features in the coring area.     

Changes in Huanghe （Yellow） River estuary since artificial re-routing in 1996

With the combination of historical data, field observations and satellite remotely sensed images(Landsat TM/ETM and CBERS), changes in Huanghe (Yellow) River estuary since 1996 when artificial Chahe distributary was built up were studied, mainly including water and sediment discharge from the river, tides, tidal currents, suspended sediment diffusion, coastline changes and seabed development. During following six and half years (up to the end of 2002), runoff and sediment loads into the river mouth declined dramatically. At the beginning of the re-routing, abundant sediment loads from the river filled up nearshore shallow water areas so that the newborn delta prograded quickly. With rapid decrease of sediment loads transported to the estuary, the delta retrograded. In 1997, subaerial tip of the abandoned delta receded 1.5km; its annual mean recession rate was about 150 m in following years. In addition, marine dynamic condition near the artificial outlet had also changed. Under the interaction of ocean and river flow, most of incoming sediment loads deposited in the vicinity of the outlet. Seabed erosion occurred at the subaqueous delta front. Between 1999 and 2002, erosion thickness averaged at 0.3 m in the subaqueous delta of 585.5 km2.     

Modern sedimentation rates and sedimentation feature in the Huanghe River estuary based on210Pb technique

Based on²¹⁰Pb technique, sedimentation rates of 11 cores collected from the Huanghe River estuary were determined. CaCO₃ distribution of 4 cores chosen from among these was measured. Profiles of²¹⁰Pb in the cores showed that the distribution of²¹⁰Pb activity decayed with depth, appeared in stages and in more than one segment. The sedimentation rates,²¹⁰Pb and CaCO₃ data have similar distribution trend in the 4 cores. The profiles of²¹⁰Pb and CaCO₃ were used to study sedimentation intensity, transportation trend of material and sedimentation features in the corring area. Contribution No. 2230 from the Institute of Oceanology, Academia Sinica. This research was supported by the National Natural Science Foundation of China.     

TRANSFERABLE PHOSPHORUS IN SEDIMENTS OF THE HUANGHE RIVER ESTUARY ＇S ADJACENT WATERS

Based on a new idea for research on cycling of marine biogenic elements, this study showed that only the leachable form phosphorus in natural grain sizes manne sediments constitutes the transferable phosphorous in the sediments. The transferable phosphorus content in the natural grain sizes surface sediments in the Huanghe River estuary adjacent waters ranges from 58.5-69.8 μg/g, accounting for only 9.1%-11.0% of the total phosphorus content, whereas the leachable form (“transferable” )phosphorus content in the sediment after it was totally ground into powder was found to be 454.8-529.2μg/g, accounting for 73.4%-89.1% of the total phosphorus. Analysis of the correlation between thebill,ass of benthos and the leachable form (“transferable” ) phosphorus showed that most of the leachableform (“transferable”) phosphorus in the totally ground sediment did not participate in the marine biogeo chemical cycling. Furthermore, a synchronous survey on benthos showed that the biornass of meio-and maero-benthos exhibited good positive correlation with the leachable form of phosphorus in the naturalgrain sizes sediment, but peorer correlation with the leachable form (“transferable”) phosphorus in the totally ground sediment, indicating that transferable phosphorus in marine sediment is the leachable form of phosphorus in the natural grain sizes sediments, and is not the previously known leachable form(“transferable”) phosphorus obtained from the totally ground sediment.     

CLIMATIC VARIATIONS IN THE COASTALZONE- COMPARISON BETWEEN THE PORIVER DELTA (ADRIATIC SEA, ITALY) ANDTHE HUANGHE RIVER DELTA (BOHAI SEA,CHINA)

The aim of this work is to research the influence of natural climatic changes on the evolution of the coastal zone in modern times and the possible implication of human activities on the configuration of the present coastline.Comparison of data of two very far and different areas , the Po River delta, Adriatic Sea and the Huanghe River delta, Bohai Sea, reveals the planetary diffusion of climatic fluctuations and their effects on coastal evolution .     

SEDIMENTARY EVOLUTION OF MODERN HUANGHE RIVER DELTA LOBE

The sedimentary history of a Huanghe(Yellow)River delta lobe can be divided into four stages.In the first stage,the crevasse splays and short-lived distributary channel deposits in the subaerial deltaand sheet silt in the subaqueous delta were well developed.In the second stage,further differentiationof sedimentary environments occurred in the subaerial delta lobe(distributary channel,natural levee,flood plain,central lower delta plain and lateral lower delta plain)and the subaqueous delta lobe(prodelta,delta front and delta lateral).In the third stage,crevasse splay and short-lived distributarychannel deposits mostly occurred in the lower or lower-middle part of the subaerial delta lobe,andsheet silt accumulated off the river mouth.In the fourth stage,the abandoned lobe was reworked.The common vertical sequence of the modern Huanghe River delta showed alternating clayey silt andsilt layers.A complete sequence from prodelta to upper delta plain was commonly composed of twoor more delta lobes.     

Nitrogen and phosphorus budgets of the Changjiang River estuary

Eutrophication has emerged as a key environmental problem in Chinese coastal waters, especially in the Changjiang (Yangtze) River estuary. In this area, large nutrient inputs result in frequent harmful algal blooms and serious hypoxia in bottom waters. Four cruises were made in the estuary in 2006 to assess the concentration and distribution of dissolved inorganic nitrogen (DIN) and phosphorus (DIP). The concentration of DIN decreased gradually in a linear relationship with salinity from the river mouth to ...     

An approach to the age of Huanghe River in shelf regions of Yellow Sea and Bohai Sea

There are two different opinions on the formation history of Huanghe （Yellow） River. One postulates that Huanghe River might have come into existence before Tertiary. The other supposes that it joined up into a long river only in the last stage of Late Pleistocene. The appearance of Huanghe River is believed to have close relation to the uplifting of Tibetan Plateau. It is not likely that it could have come into being before its high elevation riverhead was formed. Today Huanghe River occurred probably during the recession of the sea in glacial periods. In the last glacial age, the climate was very harsh in the area north of the modern estuary of Changjiang （Yangtse） River; some areas were permafrost and the others barren deserts. At that time, eolation was the major exogenic force on exposed shelf. Beginning from 12 Ka BP, the global climate warmed up, resulting in gradual disappearance of continental mountain glaciers retreated, and sea level rose. Consequently, Huanghe River was replenished with water to become modern river system. With continued rising of sea level, Huanghe River delta moved continuously eastward.     

THE SYSTEMATIC STRUCTURE OF THE ENVIRONMENT AND RESOURCES OF THE HUANGHE RIVER DELTA

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三亚河入海口与感潮河段悬浮物分布特征及潮汐之影响

河流入海口及感潮河段是陆海相互作用藕合带，受径流和潮汐的共同作用，具有独特的海洋环境。三亚河位于三亚湾的东侧，是注入三亚湾的最大河流，其流程28．8km，集雨面积337．02km^2，河床平均坡降6．09‰，总落差459．21m，三亚河属潮汐河流，平均每日纳潮量达490万立方米，年径流量为179亿立方米，现实际日纳潮量为253立方米、年径流量为92亿立方米。近年来，国内学者已对三亚湾海域开展了若干研究，如中国科学院南海海洋研究所何雪琴、南京大学海岸与海岛开发教育部重点实验室毛龙江等都先后报道过三亚湾的研究结果，但对三亚河口及感潮段悬浮物分布的研究目前尚未见报道。本文通过分析监测结果，研究了三亚河入海口及感潮河段悬浮物分布特征和潮汐对其影响。     

Several problems about the eco-environmental research on the source regions of the Changjiang River and the Huanghe River

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CHEMICAL WEATHERING PROCESSES AND ATMOSPHERIC CO_2 CONSUMPTION OF HUANGHE RIVER AND CHANGJIANG RIVER BASINS

1 INTRODUCTIONThe atmospheric CO2consumed by rock weathering haslong been recognized as providing a major loss of car-bon and decreasing the atmospheric CO2(STALL-ARD and EDMOND, 1981; MEYBECK, 1983).The 0.7×109 -0.8 ×109t of carbon derived from atmo-sp…     

三亚河入海口与感潮河段悬浮物分布特征及潮汐之影响

<正>河流入海口及感潮河段是陆海相互作用藕合带[1],受径流和潮汐的共同作用,具有独特的海洋环境。三亚河位于三亚湾的东侧,是注入三亚湾的最大河流,其流程28.8 km,集雨面积337.02 km2,河床平均坡降6.09‰,总落差459.21 m,三亚河属潮汐河流,平均每日纳潮量达490万立方米,年径流量为179亿立方米,现实际日纳潮量为253立方米、年径流量为92亿立方米。近年来,国内学者已对三亚湾海域开展了若干研究,如中国科学院南海海洋研究所何雪琴[2]、南京大学海岸与海岛开发教育部重点实验室毛龙江等[3]都先后报道过三亚湾的研究结果,但对三亚河口及感潮段悬浮物分布的研究目前尚未见报道。本文通过分析监测结果,研究了三亚河入海口及感潮河段悬浮物分布特征和潮汐对其影响。