Nutrient deposition over the past 60 years in a reservoir within a medium-sized agricultural catchment

Yunqi Zhang; Zhehong Wu; Mingyang Xu; Zengli Pei; Xue Lu; Decheng Zhang; Tong Wu; Bao Li; Shujian Xu

doi:10.1016/j.scitotenv.2020.142896

Nutrient deposition over the past 60 years in a reservoir within a medium-sized agricultural catchment

Sci Total Environ. 2021 Apr 10:764:142896. doi: 10.1016/j.scitotenv.2020.142896. Epub 2020 Oct 14.

Authors

Yunqi Zhang¹, Zhehong Wu², Mingyang Xu², Zengli Pei², Xue Lu², Decheng Zhang², Tong Wu², Bao Li³, Shujian Xu³

Affiliations

¹ National Forestry and Grassland Administration Key Laboratory of Forest Resources Conservation and Ecological Safety on the Upper Reaches of the Yangtze River, College of Forestry, Sichuan Agricultural University, Chengdu 611130, China; Shandong Provincial Key Laboratory of Water and Soil Conservation and Environmental Protection, Linyi University, Linyi, Shandong 276005, China. Electronic address: zhangyunqi@sicau.edu.cn.
² National Forestry and Grassland Administration Key Laboratory of Forest Resources Conservation and Ecological Safety on the Upper Reaches of the Yangtze River, College of Forestry, Sichuan Agricultural University, Chengdu 611130, China.
³ Shandong Provincial Key Laboratory of Water and Soil Conservation and Environmental Protection, Linyi University, Linyi, Shandong 276005, China.

PMID: 33757257
DOI: 10.1016/j.scitotenv.2020.142896

Abstract

Widespread dam construction has reduced the hydrological connectivity of catchments of various sizes. Nutrients lost from upper catchments can be intercepted by dams and deposited in reservoir sediments, and this reduces downstream nutrient transportation. Few previous studies have assessed historical nutrient deposition rates (NDRs) in man-made reservoirs. Using ¹³⁷Cs and ²¹⁰Pb_ex deposition chronologies, this paper examines the total nitrogen (TN), total phosphate (TP), and organic matter (OM) concentrations in six sediment cores recovered from Xujiaya reservoir (catchment area 580 km²), provides estimates of historical NDRs by referencing the original capacity curve, and explores temporal changes to the NDR since dam construction. The results show that anthropogenic sources resulted in the increase in nutrient concentrations in the upper parts of the cores, whereas natural sources were the main contributors to nutrient deposition across the whole reservoir. In addition, sediment supply from the catchment was the main source of the nutrients deposited in the reservoir, and the changing patterns of NDRs were overall regulated by sediment yields. The TN, TP, and OM profiles in the six cores, together with the historical NDRs, reflect the pattern of nutrient deposition in the reservoir derived from this agricultural catchment over the past 60 years. The results provide new insight into the effect of dam construction on nutrient deposition at a medium-sized catchment scale against a background of recent environmental change influenced by human activity.

Keywords: Dam; Human activity; Medium-sized catchment; Nutrient deposition.