Divergence of stable isotopes in tap water across China

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.

Water Source Signatures in the Spatial and Seasonal Isotope Variation of Chinese Tap Waters

“…We estimate a tap water line , expressing the correlation between H and O isotope ratios for Chinese tap water, using ordinary least squares regression, as δ 2 H = 7.66 δ 18 O + 5.81 ( r 2 = 0.94, p < 0.01, n = 222) using station means, or δ 2 H = 7.57 δ 18 O + 5.14 ( r 2 = 0.93, p < 0.01, n = 2879) using raw monthly data. The slope and intercept of the tap water line are less than those of global meteoric water line ( δ 2 H = 8 δ 18 O + 10; Craig, ), but close to those in China's precipitation ( δ 2 H = 7.48 δ 18 O + 1.01, based on 928 monthly samples during 2005–2010, Liu et al, ), and a previously published tap water line in China ( δ 2 H = 7.72 δ 18 O + 6.57 using 780 tap water samples; Zhao et al, ).…”

“…Monthly variation in tap water δ 2 H at two typical areas: (a) 34–36°N, 112–114°E, and (b) 30–32°N, 120–122°E. The stations with IDs of five digitals (e.g., 14,050) are collected in this study, and the IDs of letter “S” and two digitals (e.g., S56) are acquired from Zhao et al (). The geographic coordinates of the selected stations are shown in Table S1 in the supporting information.…”

“…The stable isotope composition in China's tap water may be an effective source of information, complimentary to traditional records, to understand the water supply regime and resource management. Recently, the first measurements of tap water isotopes across China were reported (Zhao et al, ), but further studies expanding the available data and exploring the implications of tap water isotope variability in China are needed. In this study, an enhanced observation network was established to provide monthly tap water sampling across China.…”

“…The stable isotope composition in China's tap water may be an effective source of information, complimentary to traditional records, to understand the water supply regime and resource management. Recently, the first measurements of tap water isotopes across China were reported (Zhao et al, 2017), but further studies expanding the Water Resources Research RESEARCH ARTICLE…”

Tracking the fate of deposited nitrogen and its redistribution in a subtropical watershed in China

“…Therefore, the local meteoric water line (LMWL) slope for throughfall (6.54) and the soil solution (6.94) exhibited strong kinetic isotopic effects via evaporation processes (Evaristo, Jasechko, & Mcdonnell, ; McDonnell, ). Compared with the Chinese meteoric water line (LMWL; δD = 7.90δ 18 O + 8.20), which is the average equation used for meteoric water lines, the LMWL of the Xiangxi River watershed yielded different slopes and intercepts at 8.57 and 21.36, respectively, indicating a humid moist origin (Zhao et al, ). This is because temperature, latitude, and humidity are relatively high in southern China (Good, Noone, & Bowen, ).…”