Investigation on spatial variability and influencing factors of drinking water iodine in Xinjiang, China.

Zhen Yang,Chenchen Wang,Yahong Sun,Yanwu Nie,Maozai Tian,Yimu Yuan,Yuxia Zhang,Yuhua Ma,Liping Zhang,Vassilis G Aschonitis

doi:10.1371/journal.pone.0261015

Abstract

Background and objectivesXinjiang is one of the areas in China with extremely severe iodine deficiency. The health of Xinjiang residents has been endangered for a long time. In order to provide reasonable suggestions for scientific iodine supplementation and improve the health and living standards of the people in Xinjiang, it is necessary to understand the spatial distribution of iodine content in drinking water and explore the influencing factors of spatial heterogeneity of water iodine content distribution.MethodsThe data of iodine in drinking water arrived from the annual water iodine survey in Xinjiang in 2017. The distribution of iodine content in drinking water in Xinjiang is described from three perspectives: sampling points, districts/counties, and townships/streets. ArcGIS was used for spatial auto-correlation analysis, mapping the distribution of iodine content in drinking water and visualizing the distribution of Geographically Weighted Regression (GWR) model parameter. Kriging method is used to predict the iodine content in water at non-sampling points. GWR software was used to build GWR model in order to find the factors affecting the distribution of iodine content in drinking water.ResultsThere are 3293 sampling points in Xinjiang. The iodine content of drinking water ranges from 0 to 128 μg/L, the median is 4.15 μg/L. The iodine content in 78.6% of total sampling points are less than 10 μg/L, and only that in the 3.4% are more than 40 μg/L. Among 1054 towns’ water samples in Xinjiang, 88.9% of the samples’ water iodine content is less than 10 μg/L. Among the 94 studied areas, the median iodine content in drinking water in 87 areas was less than 10 μg/L, those values in 7 areas were between 10–40 μg/L, and the distribution of water iodine content in Xinjiang shows clustered. The GWR model established had found that the effects of soil type and precipitation on the distribution of iodine content in drinking water were statistically significant.ConclusionsThe iodine content of drinking water in Xinjiang is generally low, but there are also some areas which their drinking water has high iodine content. Soil type and precipitation are the factors affecting the distribution of drinking water iodine content, and are statistically significant (P<0.05).

Highlights

Iodine is an essential trace element for the human body, and its function is mainly to regulate physical and intellectual development and control energy metabolism through the synthesis of thyroxine [1]
Soil type and precipitation are the factors affecting the distribution of drinking water iodine content, and are statistically significant (P
The iodine content of drinking water data in each study area was collected based on the median iodine content of drinking water in each township and sub-district, and the water iodine content value of each town and sub-district refers to the median of sampling points within its jurisdiction

Summary

Introduction

Iodine is an essential trace element for the human body, and its function is mainly to regulate physical and intellectual development and control energy metabolism through the synthesis of thyroxine [1]. Iodine deficiency in children may cause growth retardation, mental retardation, strabismus amblyopia, goiter and other symptoms [3]. Long-term iodine deficiency can result in irreversible physical and mental damage to adults. Iodine supplementation for key populations such as children and women has alleviated the current effects of iodine deficiency. The rate of goiter among children decreased from 43.29% in 1995 to 0.72% in 2019 and the median urinary iodine level in children and pregnant women and the consumption rate of qualified iodized salt have steadily increased [5]. There are regional value differences in the distribution of urinary iodine level, and pregnant women in some areas are at the risk of iodine deficiency [6]. Xinjiang is one of the areas in China with extremely severe iodine deficiency. In order to provide reasonable suggestions for scientific iodine supplementation and improve the health and living standards of the people in Xinjiang, it is necessary to understand the spatial distribution of iodine content in drinking water and explore the influencing factors of spatial heterogeneity of water iodine content distribution

Methods

Results

Discussion

Conclusion