Ten-year change of total phosphorous pollution in the Min River, an upstream tributary of the Three Gorges Reservoir

Abstract

Understanding the spatial and temporal variation of nutrient concentrations, loads and their distribution from upstream tributaries is important for management of large lakes and reservoirs. The Min River is an important tributary of the upper reaches of the Three Gorges Reservoir (TGR) that contributes about 20 % of the inflow water from the Yangtze River to the TGR. It is also one of the main phosphorous sources of the TGR. In this study, total phosphorous (TP) concentrations and hydrological data from 2004 through 2014 for 13 sites in Min River and its tributaries were analyzed. The result suggested that the concentration of TP was comparatively lower in the upstream of the Min River and Dadu River, but tended to increase in recent years. Additionally, the TP pollution status in the Min River basin has gradually evolved from local pollution to whole-basin pollution. The concentration of TP in the Min River main stream increased, decreased and then increased again along the waterway. Pollution from nonpoint sources was the main contribution in the upstream portion and Outer River basin of Min River. Pollution from point sources was more serious than that from nonpoint sources in Chengdu, Meishan and Leshan segment. Specifically, TP pollution in Min River of Chengdu segment (Huanglongxi, Inner River) was primarily affected by urbanization, while Leshan segment (Yuebo) was mainly affected by glyphosate production. Controlling pollution from nonpoint sources and improving the sewage collection rate to reduce TP loads will be the primary task in the upstream portion and Outer River basin. Point source pollution controlling will still be the primary task associated with water quality management in the Inner River (Chengdu segment) and the downstream (Leshan segment) basin of Min River for the foreseeable future. Pollution from both point sources and nonpoint sources should be cared in the other area of Min River basin.

Effects of Hydrological Regime on Foliar Decomposition and Nutrient Release in the Riparian Zone of the Three Gorges Reservoir, China

“…The study was conducted at a revegetation demonstration site of the Ruxi watershed of Zhong County, Chongqing Municipality (N30°24′16′′ and E108°08′03′′), near the riparian zone of the TGR. After the TGR reached an average water storage level of 175 m in 2010, a very large area of land–water ecotone formed, covering an area of nearly 350 km 2 ( Yangtze River Water Resources Commission, 1999 ; Wang, 2003 ; Li et al, 2013 ; Ren et al, 2016 ).…”

How fish traits and functional diversity respond to environmental changes and species invasion in the largest river in Southeastern China

“…Similar factors have been recognized in the Min River. For example, temperature and precipitation were increased by around 1.5 • C and 390 mm on average in 2015 compared with 1979 in the basin, respectively; human interferences, such as land-use/cover changes under urbanization, dam construction, and agriculture, have been intensified during the past decades (Ma et al, 2020;Ren et al, 2016;Zhao et al, 2016); several invasive species have been identified in the basin (Deng et al, 2020). The synergic effect of these factors might contribute to the loss of habitat suitability for fishes in the Min River.…”

“…Several invasive species have been identified in this river (Deng et al, 2020). Human interferences, such as urbanization, dam construction, and agriculture, have inevitably changed its ecological environments (Ma et al, 2020;Ren et al, 2016;Zhao et al, 2016). Temperature and precipitation are continuously changing in the basin (Deng et al, 2020).…”

Heterogeneous leaves of predominant trees species enhance decomposition and nutrient release in the riparian zone of the Three Gorges Reservoir

“…Currently, the decreasing water quality has become a major environmental concern in the TGR 5,6 . Studies have shown that algal blooms frequently develop in the tributary backwaters of the TGR due to the accumulation of nutrients [e.g., nitrogen (N) and phosphorus (P)] triggered by these water level changes in the riparian zone 7,8 . Riparian vegetation restoration is a crucial step for addressing the abovementioned environmental issues of the TGR 9,10 .…”