Characteristics of and Influencing Factors of Hydrochemistry and Carbon/Nitrogen Variation in the Huangzhouhe River Basin, a World Natural Heritage Site.

Chenpeng Hu,Yuan Li,Ziqi Liu,Kangning Xiong,Renkai Zhang,Xiaoxi Lyu

doi:10.3390/ijerph182413169

Abstract

In karst areas, the characteristics of water chemistry and carbon and nitrogen are of great significance to basic research. The contents of Ca2+, Mg2+, K+, Na+, HCO3−, SO42−, NO3−, Cl−, dissolved organic carbon (DOC), and total nitrogen (TN) in water samples from 18 rivers and 14 springs in the Huangzhouhe River Basin were determined. The results showed that the water chemistry type in the Huangzhouhe River Basin is HCO3-Ca-Mg. The chemical composition is mainly affected by dolomite weathering and also by ion exchange and other human activities. The river and spring DIC remain at the same level in the upper and middle reaches and decrease in the lower reaches. The NO3-N and TN of river water and TN of spring water increase in the middle reaches, while NO3-N of spring water decreases in the lower reaches. The DOC in the basin increases with the increase of SO42− and Cl−, mainly due to the human influence of agricultural and domestic sewage. In the basin, the NO3-N and TN in spring water are larger, and the DOC in river water is larger, mainly because there are more phytoplankton and human activities in the river water. The carbon and nitrogen in the Huangzhouhe River Basin are mainly HCO3− and NO3− ions. The evaluation of pH, Cl−, NO3-N, SO42−, and TDS shows that the water quality is good and the ecological environment is good.

Highlights

Published: 14 December 2021The input of terrestrial erosion material from rivers to the ocean is a key part of the biogeochemical cycle
Through the study of the temporal and spatial dynamics of the contents of anions and cations in the Huangzhouhe River Basin, we revealed the hydrogeochemical characteristics of typical subtropical dolomite basins in this study
We found that river and spring water samples within the Huangzhouhe

Summary

Introduction

Published: 14 December 2021The input of terrestrial erosion material from rivers to the ocean is a key part of the biogeochemical cycle. River chemistry is influenced by many natural geochemical processes such as climate, structure, weathering, and vegetation cover [1,2,3,4]; lithology (rock weathering) is the dominant factor in these processes because rock is the main source of dissolved load in river water [5,6]. The content and distribution characteristics of ions in rivers are influenced and controlled by many factors such as precipitation, temperature, topography, altitude, recharge type, runoff and discharge processes, land use type, and surface lithology. The characteristics of water chemistry and their variation can indicate the main ion sources of the water body and reflect the influence of human activities on water environments. The inorganic carbon dissolution load in river water comes from different sources: rock dissolution, precipitation, and human input [8]

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