Divergence of stable isotopes in tap water across China

Sihan Zhao,Qiang Tie,Fuqiang Tian,Yaling Liu,Hongchang Hu,Lixin Wang,Chunxiang Shi

doi:10.1038/srep43653

Abstract

Stable isotopes in water (e.g., δ2H and δ18O) are important indicators of hydrological and ecological patterns and processes. Tap water can reflect integrated features of regional hydrological processes and human activities. China is a large country with significant meteorological and geographical variations. This report presents the first national-scale survey of Stable Isotopes in Tap Water (SITW) across China. 780 tap water samples have been collected from 95 cities across China from December 2014 to December 2015. (1) Results yielded the Tap Water Line in China is δ2H = 7.72 δ18O + 6.57 (r2 = 0.95). (2) SITW spatial distribution presents typical “continental effect”. (3) SITW seasonal variations indicate clearly regional patterns but no trends at the national level. (4) SITW can be correlated in some parts with geographic or meteorological factors. This work presents the first SITW map in China, which sets up a benchmark for further stable isotopes research across China. This is a critical step toward monitoring and investigating water resources in climate-sensitive regions, so the human-hydrological system. These findings could be used in the future to establish water management strategies at a national or regional scale.

Highlights

The Global Network of Isotopes in Precipitation (GNIP), established in 1961 by International Atomic Energy Agency (IAEA), is the largest database constituted for monitoring isotopic compositions of precipitation
The Tap Water Line (TWL) of China based on the 780 tap water analyses was: δ2H = 7.72δ18O + 6.57 (r2 = 0.95) (Fig. 2)
The tap water data clustered near Global Meteoric Water Line (GMWL: δ2H = 8δ18O + 10)[30]

Summary

Introduction

The Global Network of Isotopes in Precipitation (GNIP), established in 1961 by International Atomic Energy Agency (IAEA), is the largest database constituted for monitoring isotopic compositions of precipitation. In order to examine the relationships between tap water isotope and meteorological factors, meteorological data - including the precipitation amount (P, mm), temperature (T, °C), relative humidity (RH, %) and air pressure (PR, kpa) - were collected at observation station in the same city of each sampling location. There was a large range in δ18O and δ2H values in tap water samples across China.

Results

Conclusion