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The safety of water delivery and water quality in the South to North Water Transfer Project is important to China. When sudden pollution accidents happen in this project, a high-accuracy water quality model is needed to simulate contaminant transport. Data assimilation algorithm can be used to improve the accuracy of model, and a water quality model with three dimensional variational data assimilation (3DVAR-WQM), are developed in this paper. A contaminant transport experiment has been conducted for verifying the feasibility and accuracy of this model. After analyzing the simulated results in 3DVAR-WQM and the standard water quality model without assimilation, it has been found that the model with simulation estimates the arrival time and value of the peak concentration more accurately, and that the error between the simulated and observed data in this model is little. At the same time, the root mean square error of this model are smaller. This paper increases forecasting skills through data assimilation techniques, and it provides a tool for improving water quality management in the South to North Water Transfer Project of China. [ABSTRACT FROM AUTHOR]

River classification has emerged as a major application of environmental science, which can overcome the defects of traditional methods in focusing on the single objective of maintaining specified, valued features of ecosystems. However, current efforts to classify rivers by hydrologic processes may result in a growing temptation to ignore ecological variability across basins. Thus, an eco-functional classification is proposed for river management in the Pearl River Basin. This method views ecological functions as fundamental characteristics of riverine systems and provides a framework for dividing a basin into eco-specific categories according to the heterogeneity of the primary ecological functions. In addition, we proposed specific environmental flow methodologies corresponding to three typical river reaches of the basin by perceiving the key attributes of flow variability. In the upstream region of the West River, flow velocity and wetted perimeter are considered as the key attributes of maintaining fish habitat; in a small-sized mountainous tributary of the North river, we choose water surface area to maintain the continuity and biodiversity of the river; while for the aspect of river landscape in the midstream reach of the East River, water level is crucial for maintaining the aesthetic value. This research highlights the ecologically relevant heterogeneity that occurs within and among regions of a basin, and is expected to contribute to a simpler and more comprehensive river management. [ABSTRACT FROM AUTHOR]

Objective: To study the effects of low dose radiation (LDR) on tumor apoptosis, cell cycle progression and changes of apoptosis-related protein Bcl-2 in tumor-bearing mice. Methods: Male mice of Kunming strain were implanted subcutaneously with S180 sarcoma cells in the left inguen as an in situ experimental animal model. Seven days later, the mice were subjected to 75 mGy whole-body γ-irradiation. At 24 and 48 h after the irradiation, all mice were sacrificed. The tumor sizes were measured, and tumor cell apoptosis and cell cycle progression were analyzed by flow cytometry. The expression of apoptosis-related protein Bcl-2 and the apoptotic rate of tumor cells were observed by immunohistochemistry and electron microscopy. Results: Tumors grew significantly slower after LDR (P<0.05). The tumor cells were arrested in G1 phrase and the expression of Bcl-2 protein decreased at 24 h. Apoptotic rate of tumor cells was increased significantly at 48 h after LDR (P<0.01). Conclusion: LDR could cause a G1-phase arrest and increase the apoptosis of tumor cells through the low level of apoptosis-related protein bcl-2 in the tumor-bearing mice. The organized immune function and anti-tumor ability are markedly increased after LDR. Our study provides practical evidence of clinical application to cancer treatment. [ABSTRACT FROM AUTHOR]