Stable H-O Isotopic Composition and Water Quality Assessment of Surface Water and Groundwater: A Case Study in the Dabie Mountains, Central China.

Kunhua Yang,Peng Zhang,Chao Song,Guilin Han

doi:10.3390/ijerph16214076

Abstract

In order to understand the water cycle and assess the water quality for irrigation purposes in the Upper Pi River Basin (UPRB), which is the northern slope of the Dabie Mountains, 68 surface water and groundwater samples were collected and analyzed for H-O isotopes and hydrochemistry during the high-flow season in 2017 and 2018. The results show that ranges of hydrogen and oxygen isotopic composition (δ2H: −68.8‰ to −40.8‰, δ18O: −10.05‰ to −5.05‰) are controlled by the medium latitude and high altitude of the UPRB. Among different types of water, the δ2H and δ18O values can be ordered as follows: reservoir water < spring water ≈ river water < pond water. The water of the upstream medium and small reservoir is enriched with lighter isotopes that is likely related to more exchange with rainwater and less residence time; however, large reservoirs are similar to the upstream river and spring in terms of the H-O isotopic composition. Hydro-chemical facies are dominated by the Ca-HCO3 type in the UPRB, which reflects fresh recharged water from rainfall, and few samples are of the Ca-Cl type that is caused by intensive evaporation. The water quality for irrigation purposes was also evaluated. According to the Wilcox diagram, United States Salinity Laboratory (USSL) diagram, magnesium hazard, and Kelly’s ratio, all water samples have been considered suitable for irrigation water.

Highlights

In mountainous areas, climate change and human activities can have a thorough impact on the water cycle, such as increased precipitation, evapotranspiration, and the consumption of surface water and groundwater [1,2,3]
In the Upper Pi River basin (UPRB), surface water and groundwater are mainly recharged by rainwater in the high-flow season, which refers to the abundant rainfall resource in the mountainous area
The spatial distribution of hydrogen and oxygen isotopes reflects the separation of different water bodies

Summary

Introduction

Climate change and human activities can have a thorough impact on the water cycle, such as increased precipitation, evapotranspiration, and the consumption of surface water and groundwater [1,2,3]. These changes in the meteoric water can influence biogeochemical cycles through water flow [4]. Catchment-based studies of surface water and groundwater in the UPRB are less numerous, despite the fact that it is significantly important for reducing the risk of flooding disasters and understanding the impacts of climate change on the water cycle. The Pi River is the main water source for a 7750 km irrigation area and about 13 million people [9], and four large reservoirs in the UPRB

Methods

Results

Conclusion