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

Xiaoqiang Li,Kunhua Yang,Man Liu,Jinke Liu,Guilin Han

doi:10.3390/ijerph16030440

Abstract

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 () is 1.5 meq/L. Calcium and followed by and 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 consumption rates are estimated at 3.7 × 105 mol/km2/a for silicate weathering and 2.2 × 105 mol/km2/a for carbonate weathering. An overestimated carbon sink (17.4 Gg ) is about 27.0% of the consumption flux via silicate weathering in the Jiulongjiang River basin, this result shows the strong effects of anthropogenic factors on atmospheric level and current and future climate change of earth.

Highlights

Chemical weathering of rocks is part of the exogenous cycle, in which periodic migration of elements occurs among lithosphere, atmosphere, biosphere and hydrosphere [1,2,3,4,5,6]
The carbon sink may be overestimated about 1.5 × 109 mol/a (17.4 Gg C/a), and this value is about 27.0% of carbon uptake via silicate weathering estimated in the Jiulongjiang River basin (JRB). These results show that the amount of CO2 consumption in the atmosphere by carbonate and silicate weathering, will be overestimated when the effects of H2 SO4 and HNO3 are ignored in the process of calculating the carbon sink
We have investigated the dissolved major ions concentrations in the JRB, where silicate rocks occupy the middle and lower reaches while carbonate rocks are mainly concentrated in the upper reaches

Summary

Introduction

Chemical weathering of rocks is part of the exogenous cycle, in which periodic migration of elements occurs among lithosphere, atmosphere, biosphere and hydrosphere [1,2,3,4,5,6]. The earth’s exogenic cycle resulted in many different interpretations of the chemical weathering of rocks on the earth surface and the global carbon cycle [8]. The relationship between chemical weathering and carbon cycle has been investigated in most of rivers in the world, remaining doubts continue to influence our understanding of connections among rock weathering, climate and the carbon cycle due to huge difference in geological environment, which leads to great uncertainty to quantitative analysis of the global carbon cycle [1,4,6,8,10]. Public Health 2019, 16, 440; doi:10.3390/ijerph16030440 www.mdpi.com/journal/ijerph

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