Affiliations: School of Materials and Environmental Sciences,
Qingdao University of Science & Technology, Qingdao 266042, China | Chemistry and Chemical Engineering College, Ocean
University of China, Qingdao 266003, China | State Key Laboratory of Estuarine and Coastal
Research, East China Normal University, Shanghai 200062, China
Abstract: 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, we propose two approaches-sea salt correction and precipitation
correction 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.
Keywords: Dongjiang River, river solutes, precipitation chemistry, atmospheric inputs, chemical weathering rate
