# Metals and Metalloids in the Urban Segment of the Lijiang River, Guilin: Spatial Distribution, Migration and Transformation Processes, and Source Apportionment

## TL;DR

This study examines metal and metalloid contamination in the Lijiang River near Guilin, finding low water pollution but elevated levels in sediments, with sources including industrial and agricultural activities.

## Contribution

The study provides a detailed source apportionment of metals and metalloids in a karst river using sediment profiles and advanced analytical methods.

## Key findings

- Sediment concentrations of Cd, Zn, As, and Pb exceed background values, indicating contamination.
- Ni, Cu, As, and Cd show higher bioavailability and mobility in the river.
- Industrial discharge and agricultural activities are significant contributors to metal contamination.

## Abstract

The Lijiang River is a typical karst landscape river and an important drinking water source for Guilin City. To evaluate its contamination of metals and metalloids, water, surface sediment and four sediment profiles were systematically collected from the Guilin urban segment in April 2023, and the distribution, mobility and potential sources of nine elements (Cr, Mn, Co, Ni, Cu, Zn, As, Cd and Pb) were analyzed. Results show that metal and metalloid concentrations in the river water are low and water quality is good, whereas sediment concentrations of Cd, Zn, As and Pb are markedly higher than the background values. Compared with other elements, Ni, Cu, As and Cd are more readily mobilized in the aqueous phase and exhibit higher bioavailability. Vertical variation coefficients of all elements in the sediment profiles are mostly below 15%, indicating a relatively stable depositional environment. Correlation analysis and positive matrix factorization identify four main sources: industrial discharge (12.5%), mixed agricultural–geogenic origin (34.3%), traffic emissions (11.9%) and geological background (41.3%). Overall, metal and metalloid contamination in the urban Lijiang River is controllable, but accumulation of Cd and other elements in sediments requires continued attention.