The Study On The Hydro-Chemical Characteristics And The Flux To The Sea About The Rivers In The East Of China

The hydro-chemical characteristics is not only a manifestation of the extent and the style of the chemical weathering,but also a reflection of environmental quality status of water body;The chemical weathering is a very important part of material geochemistry cycle and the global climate change.Basin on that,there are four part in this thesis,the first,it discuss the hydro-chemical characteristics of the rivers in the east of China, analyses the affection factor and the main style of chemical weathering;the second,it shows the differences of hydro-chemical characteristics about the given main-channel, the branches,the estuary,the lake,the reservoir and the rain water in Yangtze river basin, analyses the affection and the connection.Basin on the concentration of main ions about the given main-channel,the branches and the rain water,we estimated the contribution of the rain water to the given main-channel and the branches.From the PCA result and the contribution of the rain water,we calculate the chemical weathering rate and CO₂ consumption;the third,it analyses the changes of hydro-chemical characteristics and the flux of Yangtze river in recent years and last 50 years;the fourth,it estimates the flux of rivers transport to the seas.The following conclusions have been drawn:(1)Yellow River,Hai River,Luan River have a high TDS,they are the 3～6 times than the mean value of the world rivers,the major ions are Na⁺,Ca²⁺,Cl^-,SO₄^2- and HCO₃^-,the evaporate weathering and the human activities are the main affection;Yalv River has the weak weathering and the equivalent TDS with the mean value of the World Rivers,that effected by enough rainfall and the luxuriated plant;the TDS of Yangtze River is 2 times more than the mean value of the world rivers,the major ions are Ca²⁺,SO₄^2- and HCO₃^-,carbonate weathering is the main type in this basin,except that,the concentration of SO₄^2- and TN is effected by the pollution of industry and agriculture;the river in Zhejiang Province,the TDS of Qiantang River is a litter higher than the the mean value of the world rivers,but it lower than Yangtze River,Ling River and Ou River both lower than the mean value of the world rivers,the concentration of TDS in Jiao River, Yong River and Ao River have a large changes extent,and the changes is complicated, the possible reason is that they have a variable adventitious dissolved matter.The contribution of the rain water is important,especially for the Na⁺ and Cl^-,in their basins, silicate weathering is the main style,the seven Rivers have different CDR,and the effects for it are human activities and geology element,then with the forest coverage rate,plough area and the PDR.It is estimated that there is 26.69×10⁶mol CO₂ consumed;the rivers in Hainan Province is controlled by the rainfall,they have low TDS concentration.The contribution of the rain water is high,especially the SO₄^2-,Na⁺ and Cl^-.Silicate weathering is the main style.In Hainan Island,the CDR in Wanquan River basin and Nandu River basin are stronger than the average in the whole island,the both have litter difference.The CO₂ consumption in Nandu River basin is 7.5 times than Wanquan River basin,its proportion in the whole island is 60.52%.(2)The TDS of the reservoir is higher than the given main-channel,but the branches, the estuary and the lakes are lower than the given main-channel,it is because that the Dongting Lake has a contribution from Groundwater with a low TDS.It is estimated that there are 7.35×10⁸m³ groundwater to the east Dongting Lake,about 2.79×10⁸m³ groundwater to the west Dongting Lake,about 1.36×10⁸m³ groundwater to the south Dongting Lake,×10⁸m³,the supplied quantity is related to the area;the concentration of SO₄^2- has a increasing trend from up to down in downstream,it is effected by the pollution of industry,the concentration of TN and Cl^- have the same trend,they effected by agriculture pollution and circulation salt respectively,the contribution of the rain water in upstream and downstream is bigger than the mid-stream,rectify the concentration of the main ions,we calculate the chemical weathering rate and CO₂ consumption in Yangtze River basin:the chemical weathering rate stronger than the average of the world in the whole river basin,the upstream basin is stronger than the downstream basin and the weakest is mid-stream basin.The CO₂ consumption in upstream basin is 338.23×10⁹mol/yr,the mid-stream basin is 385.79×10⁹mol/yr,the downstream basin is 223.24×10⁹mol/yr.Yangtze River basin,its proportion in the world is 4.5%.The chemical weathering rate in all branches have the same result,in upstream is stronger than the downstream,and the weakest is the mid-stream;(3)The concentration of main ions varies clearly in different seasons,but the difference is less clearly than the discharge;there is a persistently increasing trend has been observed in the concentrations of K⁺,Na⁺,Ca²⁺,Mg²⁺,Cl^-,NO₃^-,SO₄^2- and the ratio of hardness/ alkalinity,especially the concentration of SO₄^2- and the ratio of hardness/alkalinity have a more obvious increasing trend;in contrast the concentration of SiO₃^2- and HCO₃^- show a decreasing trend.The changes of major ions mainly result from the environment acidification,the pollution emissions by human,the cyclic salt from sea and the preserved effect by reservoirs establishments etc.in recent years,the Flux of the total dissolved solutes has a decreasing trend,the flux of DIC has little changes;in last 50 years,the concentration of SiO₃^2-and HCO₃^- have decreasing trend,but NO₃^- and SO₄^2- have increasing trend,the discharge has no obvious changes,the flux of TN has obvious increasing trend,but the flux of DIC and the SiO₃^2- show a decreasing trend.(4)The total dissolved concentration of rivers in East China has a decreasing trend from north to south.In north and mid-part,there are most of rivers have a higher TDS than the average value of the world.The CDR in north is weakest,and then is the south, the middle is strongest.The CO₂ consumed is about 1569.5×10⁹mol/yr in East China.It is estimated that,the seas(The East Sea,The Yellow Sea,The South Sea and The Bo Sea) accept the water from the rivers is about 15923×10⁸m³,the total solid mass is about 17463.6×10⁴t,the total dissolved solutes is about 127.45×10⁶t,but the distribution to the four sea is inequable,but the distribution proportion of discharge,the total dissolved solutes,the quantity of DIC in each sea are similar,the total solid mass is different.