Hydro-Geochemistry of the River Water in the Jiulongjiang River Basin, Southeast China: Implications of Anthropogenic Inputs and Chemical Weathering

• Main Authors: Xiaoqiang Li, Guilin Han, Man Liu, Kunhua Yang, Jinke Liu
• Format: Article
• Language: English
• Published: MDPI AG 2019-02-01
• Series: International Journal of Environmental Research and Public Health
• Subjects: chemical weathering; major ions; human activities; Jiulongjiang River; southeast China
• Online Access: https://www.mdpi.com/1660-4601/16/3/440

This study focuses on the chemical weathering process under the influence of human activities in the Jiulongjiang River basin, which is the most developed and heavily polluted area in southeast China. The average total dissolved solid (TDS) of the river water is 116.6 mg/L and total cation concentration (<inline-formula> <math display="inline"> <semantics> <mrow> <msup> <mrow> <mi>TZ</mi> </mrow> <mo>+</mo> </msup> </mrow> </semantics> </math> </inline-formula>) is 1.5 meq/L. Calcium and <inline-formula> <math display="inline"> <semantics> <mrow> <msubsup> <mrow> <mi>HCO</mi> </mrow> <mn>3</mn> <mo>&#8722;</mo> </msubsup> </mrow> </semantics> </math> </inline-formula> followed by <inline-formula> <math display="inline"> <semantics> <mrow> <msup> <mrow> <mi>Na</mi> </mrow> <mo>+</mo> </msup> </mrow> </semantics> </math> </inline-formula> and <inline-formula> <math display="inline"> <semantics> <mrow> <msubsup> <mrow> <mi>SO</mi> </mrow> <mn>4</mn> <mrow> <mn>2</mn> <mo>&#8722;</mo> </mrow> </msubsup> </mrow> </semantics> </math> </inline-formula> constitute the main species in river waters. A mass balance based on cations calculation indicated that the silicate weathering (43.3%), carbonate weathering (30.7%), atmospheric (15.6%) and anthropogenic inputs (10.4%) are four reservoirs contributing to the dissolved load. Silicates (SCW) and carbonates (CCW) chemical weathering rates are calculated to be approximately 53.2 ton/km²/a and 15.0 ton/km²/a, respectively. When sulfuric and nitric acid from rainfall affected by human activities are involved in the weathering process, the actual atmospheric <inline-formula> <math display="inline"> <semantics> <mrow> <msub> <mrow> <mi>CO</mi> </mrow> <mn>2</mn> </msub> </mrow> </semantics> </math> </inline-formula> consumption rates are estimated at 3.7 &#215; 10⁵ mol/km²/a for silicate weathering and 2.2 &#215; 10⁵ mol/km²/a for carbonate weathering. An overestimated carbon sink (17.4 Gg <inline-formula> <math display="inline"> <semantics> <mrow> <mrow> <mi mathvariant="normal">C</mi> <mo>/</mo> <mi mathvariant="normal">a</mi> </mrow> </mrow> </semantics> </math> </inline-formula>) is about 27.0% of the <inline-formula> <math display="inline"> <semantics> <mrow> <msub> <mrow> <mi>CO</mi> </mrow> <mn>2</mn> </msub> </mrow> </semantics> </math> </inline-formula> consumption flux via silicate weathering in the Jiulongjiang River basin, this result shows the strong effects of anthropogenic factors on atmospheric <inline-formula> <math display="inline"> <semantics> <mrow> <msub> <mrow> <mi>CO</mi> </mrow> <mn>2</mn> </msub> </mrow> </semantics> </math> </inline-formula> level and current and future climate change of earth.