Occurrence of Camallanus cotti in greatly diverse fish species from Danjiangkou Reservoir in central China

Abstract To investigate the retention efficiency and mechanism of nitrogen of Vegetative filter strips (VFSs) in the Danjiangkou Reservoir area, simulated runoff discharging experiments were carried out in a new-established Bermuda VFS. The results showed that the Bermuda VFS reduced 73.1-86.1 % of surface runoff through infiltration. The outflow rate of runoff increased first and then became stable with time. The concentration reduction rates (CRRs) and load reduction rates (LRRs) of NH3-N increased initially and then decreased with the increase of inflow concentration. The average CRRs and LRRs of NH3-N in three treatments ranged 66.1-90.3 % and 90.0-96.7 %, respectively. The concentration reduction of NH3-N was primarily achieved by soil adsorption. The optimal inflow concentration of NH3-N for the optimum CRR was between 0.65 and 3.52 mg/dm3. The CRRs and LRRs of NO3-N fluctuated between 6.8-14.0 % and 72.0-77.9 % in three treatments. The concentration reduction of NO3-N was primarily achieved by plant uptake and soil microbe assimilation. The optimal inflow concentration of NO3-N for optimum CRR exceeded 6.78 mg/dm3. The CRRs and LRRs of TN increased with the increase of inflow concentrations. The average CRRs in the low, moderate and high treatments reached 9.7, 14.8 and 27.4 %, respectively, and the average LRRs reached 72.1, 74.3 and 81.2 %, respectively. The optimal inflow concentration of TN for optimum CRR exceeded 10.21 mg/dm3. The study showed that Bermuda grass can retain nitrogen in runoff efficiently and should be promoted around the Danjiangkou reservoir.

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Spatio-temporal variability in the thermal regimes of the Danjiangkou reservoir and its downstream river due to the large water diversion project system in central China

Hydrology Research ◽

10.2166/nh.2015.210 ◽

2015 ◽

Vol 47 (1) ◽

pp. 104-127 ◽

Cited By ~ 6

Author(s):

Pan Chen ◽

Lan Li ◽

Hongbin Zhang

Keyword(s):

Water Temperature ◽

Temperature Change ◽

Ecological Impact ◽

Central China ◽

Water Diversion ◽

Regulated Rivers ◽

Danjiangkou Reservoir ◽

Spatio Temporal ◽

Large Water ◽

Spawning Periods

Understanding water temperature variation in regulated rivers and reservoirs becomes increasingly important as the environment and ecosystem are approaching their thermal limits. In this paper, a multi-model approach is used to quantitatively access the spatio-temporal change in thermal structures of the Danjiangkou reservoir and its downstream river. The area is subject to thermal and hydrological alterations due to three large water diversion projects and related auxiliary projects, including a project to heighten the Danjiangkou dam and two small downstream reservoirs. It is found that the Danjiangkou dam heightening project alters water temperature seasonally, increasing it in winter and decreasing it in summer; while the three large water diversion projects and the two small downstream reservoirs mitigate the effect. Water temperature change in the downstream river is also studied from the aspects of release temperature and release discharge of the Danjiangkou reservoir. The former mainly changes the water temperature near the dam, while the latter affects the recovery rate and the recuperation distance. Ecological impact of the water temperature change is discussed based on the spawning of fish, indicating that the spawning periods may lag behind and the optimal spawning locations may move downstream.

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