Particulate organic carbon (POC) and its isotopic composition were measured monthly in the ChangjiangRiver (at Sta. Datong)for a whole year. It shows that their seasonal distribution has an obvious change and is simil...Particulate organic carbon (POC) and its isotopic composition were measured monthly in the ChangjiangRiver (at Sta. Datong)for a whole year. It shows that their seasonal distribution has an obvious change and is similarto that of the Huanghe River. The annual weighted mean of POC 13 C values of the Changjiang River is almost the same as that of the Huanghe River. Based on the data of runoff and sediment load measured daily and POC concentra-tion measured monthly the POC flux at Sta. Datong was estimated. The flux value at Datong may be considered ap-proximately to be the M flux of the Changjiang River discharging into the sea. The M flux of the Changjiang Riv-er is slightly larger than that of the Huanghe River.展开更多
The atmospheric precipitation plays an important role in influencing the river chemistry of the Dongjiang River. The atmospheric contribution to river water is estimated by reference to Cl concentration called Cl r...The atmospheric precipitation plays an important role in influencing the river chemistry of the Dongjiang River. The atmospheric contribution to river water is estimated by reference to Cl concentration called Cl ref . The Cl ref of 41 97 μmol/L represents the highest chloride concentration of the rainwater inputs to river water, thus sea salts are responsible for total Cl concentration of the Dongjiang River. According to the principal compositions of precipitation and river water, two approaches sea salt correction and precipitation correction were proposed in order to correct the contribution proportions of atmospheric precipitation on the solutes and to calculate chemical weathering rate. The results reflected that the atmospheric contribution ratios fluctuate from ～5% to ～20% of TDS(total dissolved solids) in the Dongjiang River. As compared with the other world watersheds, the lower dissolved ion contents and high runoff may result in the obvious influence of precipitation on river chemistry in the Dongjiang basin. The major elemental chemistry is mainly controlled by silicate weathering, with the anion HCO - 3 and cation Ca 2+ and Na\++ dominating the major compositions in this basin. The estimated chemical weathering rate of 15 78—23 48 t/(km 2·a) is only 40%—60% of a global average in the Dongjiang basin. Certainly, the estimated results are still under correction gradually because the effect of human activities on the precipitation chemistry has never been quantified in detail.展开更多
文摘Particulate organic carbon (POC) and its isotopic composition were measured monthly in the ChangjiangRiver (at Sta. Datong)for a whole year. It shows that their seasonal distribution has an obvious change and is similarto that of the Huanghe River. The annual weighted mean of POC 13 C values of the Changjiang River is almost the same as that of the Huanghe River. Based on the data of runoff and sediment load measured daily and POC concentra-tion measured monthly the POC flux at Sta. Datong was estimated. The flux value at Datong may be considered ap-proximately to be the M flux of the Changjiang River discharging into the sea. The M flux of the Changjiang Riv-er is slightly larger than that of the Huanghe River.
文摘The atmospheric precipitation plays an important role in influencing the river chemistry of the Dongjiang River. The atmospheric contribution to river water is estimated by reference to Cl concentration called Cl ref . The Cl ref of 41 97 μmol/L represents the highest chloride concentration of the rainwater inputs to river water, thus sea salts are responsible for total Cl concentration of the Dongjiang River. According to the principal compositions of precipitation and river water, two approaches sea salt correction and precipitation correction were proposed in order to correct the contribution proportions of atmospheric precipitation on the solutes and to calculate chemical weathering rate. The results reflected that the atmospheric contribution ratios fluctuate from ～5% to ～20% of TDS(total dissolved solids) in the Dongjiang River. As compared with the other world watersheds, the lower dissolved ion contents and high runoff may result in the obvious influence of precipitation on river chemistry in the Dongjiang basin. The major elemental chemistry is mainly controlled by silicate weathering, with the anion HCO - 3 and cation Ca 2+ and Na\++ dominating the major compositions in this basin. The estimated chemical weathering rate of 15 78—23 48 t/(km 2·a) is only 40%—60% of a global average in the Dongjiang basin. Certainly, the estimated results are still under correction gradually because the effect of human activities on the precipitation chemistry has never been quantified in detail.
