Environmental implication identification on water quality variation and human health risk assessment in the middle and lower reaches of the Hanjiang River, China

Abstract

As the longest tributary of the Yangtze River, the Hanjiang River has been a “lifeline” for the “Yangtze River Economic Belt of China”. The water quality of the middle and lower reaches of the Hanjiang River (MLHR) has received considerable attention due to environmental degradation, increasing population, and water diversion project operations during the past decade. In this study, 16 water quality parameters from 14 national water quality monitoring stations along the MLHR were collected monthly from January 2021 to December 2022. Water quality index (WQI) methods coupling multivariate statistical techniques, e.g., seasonal Mann-Kendall test (SKT) and Mantel’s test, were applied to analyze and evaluate the spatiotemporal variations of water quality under different environmental and hydrological conditions. The Hazard Quotients (HQs) were used to assess the non-carcinogenic and carcinogenic risk for adults and children via ingestion and dermal pathways. The results showed that the overall water quality in the MLHR was classified as “excellent”, with the average WQI higher than “91”, and each single water quality indicator met Class I or Class II surface water quality standards of China. Ammonia (NH₃-N), Total phosphorus (TP), Permanganate (COD_Mn), pH, and Arsenic (As) were significantly correlated with water level variations. COD_Mn and TP were decisive in explaining the WQI variations of the MLHR. NH₃-N, water temperature, pH, and dissolved oxygen were key parameters for explaining WQI variations in most regions of the MLHR. As, Cadmium (Cd), and Chromium (Cr) presented potential health risks in the MLHR and should warrant close monitoring due to their significant health implications. Due to the continuous construction and operation of cascade hydro-projects, the synchronous monitoring of water quality and hydrological data of the MLHR should be conducted in the future. This study provides a scientific reference for managing water quality in the MLHR and similar natural riverine water bodies.

Keywords:

• water quality index
• water quality variation
• heavy metal pollution
• multivariate statistic
• Hanjiang River

Authors’ contributions

Dr. Xizhi Nong: Data collection, Investigation, Conceptualization, Formal analysis, Writing-Original Draft, Draft review & editing, Funding Acquisition; Ms. Rujia Tang: Conceptualization, Methodology, Software, Writing-Original Draft; Prof. Lihua Chen: Formal analysis, Draft review & editing; Prof. Jiahua Wei: Supervison, Draft review & editing.

Consent to publish

The authors authorize the publication of the article in this journal.

Disclosure statement

The authors declare no competing interests.

Additional information

Funding

This research was funded by the Specific Research Project of Guangxi for Research Bases and Talents (No. AD22035185), the Youth Science Foundation of Guangxi (No. 2023GXNSFBA026296), the National Natural Science Foundation of China (No. 52309016), the Belt and Road Special Foundation of the National Key Laboratory of Water Disaster Prevention (No. 2022nkms06).