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

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 ( TZ + ) is 1.5 meq/L. Calcium and HCO 3 − followed by Na + and SO 4 2 − 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 CO 2 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 C / a ) is about 27.0% of the CO 2 consumption flux via silicate weathering in the Jiulongjiang River basin, this result shows the strong effects of anthropogenic factors on atmospheric CO 2 level and current and future climate change of earth.

Current Seasonal Variations in Physicochemical and Heavy Metals Parameters of Sewage Treatment Plant Effluent and Suitability for Irrigation

“…Boron, an essential element for crop plants becomes toxic above critical levels [26]. Boron in STP water contributed via chemical weathering and anthropogenic inputs [27].…”

Distribution and Contamination Assessment of Soil Heavy Metals in the Jiulongjiang River Catchment, Southeast China

“…Secondly, the applications of chemical fertilizers and nutrients in agricultural activities as the anthropogenic inputs may result in the accumulation of HMs in soils. Finally, soil erosion caused by man-made mountain development and reforestation has resulted in the reduction of soil fertility and cultivated land erosion [30,31], and these problems directly or indirectly lead to soil heavy metal pollution and reduced environmental quality.…”

Hydrochemistry and Dissolved Inorganic Carbon (DIC) Cycling in a Tropical Agricultural River, Mun River Basin, Northeast Thailand

“…Chemical weathering of silicates and carbonates is a key process for the carbon cycling at the Earth’s surface [36,37,38,39,40]. Chemical weathering is the major source of elements delivered by rivers to the oceans [41]. Carbonic acid usually accelerates silicate weathering, for instance, the incongruent dissolution of sodium feldspar to clay kaolinite by carbonic acid:2NaAlSi3normalO8(s)+9normalH2O+2normalH2CO3(aq)=Al2Si2normalO5(OH)4(s)+2Na+(aq)+2HCO3−+4normalH4SiO4(aq)…”

“…Two wastewater samples were characterized by low NO3−/Na+ concentrations, and the values were approximately 0. The SO42− may originate from various sources, such as oxidation of sulfides, the dissolution of gypsum, and acid deposition [41]. Higher DIC concentrations (7397 μmol/L) and medium δ 13 C DIC value (−11.4‰) were found in the urban sewage sample (Figure 6b), and this large amount of untreated sewage discharged from rural areas may have a huge impact on concentrations of DIC and δ 13 C DIC .…”