Abstract:Poyang Lake, which is the largest freshwater lake in China, is an important regional water resource and iconic ecosystem that has experienced a period of continuous low water level in recent years. In this paper, the Standardized Precipitation Evapotranspiration Index (SPEI) was applied to analyze the temporal variability and spatial distribution characteristics of meteorological drought over the Poyang Lake Basin during 1961-2015. In addition, correlation analysis was used to investigate the response relationship between lake level and meteorological drought in the basin. The main results showed that: (1) The decline of water level in Poyang Lake since 2000 has been dramatic, especially in autumn, when the downward speed reached 11.26 cm/day. (2) The meteorological drought in the Poyang Lake Basin has obvious seasonal characteristics, and drying tendencies in spring and autumn were relatively obvious. Following the 1960s, this basin entered a new drought period in the 2000s. (3) The results of correlation analysis showed that three-and six-month timescales were the optimum times for the lake level to respond to the SPEI in the Poyang Lake Basin. Seasonally, the correlation was best in winter and worst in autumn. Furthermore, the spatial distribution of correlations was: Hukou < Xingzi < Duchang < Wucheng < Tangyin < Kangshan. Overall, the results of this study quantified the response of lake level to meteorological drought in the context of climate change, and they provide a reliable scientific basis for water resource management in similar basins.

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Spatial and temporal variations in hydrological series are affected by both climate change and human activities. A scientific understanding of the impacts of these two main factors on runoff will help to understand the response mechanism of the water cycle in a changing environment. This study focused on Poyang Lake Basin, which contains China’s largest freshwater lake. Several approaches, including the Mann-Kendall trend test, cumulative anomaly method, Hurst exponent analysis, and slope change ratio of cumulative quantity (SCRCQ) method, were adopted to explore the characteristics of runoff variations and the respective impacts of climate change and human activities on runoff variations in the five subbasins. The results indicated that (1) from 1961 to 2015, the runoff throughout the basin fluctuated, and it decreased significantly in the 2000s. (2) Different baseline periods and measurement periods were identified for each subbasin to analyse the spatial and temporal responses of runoff to climate change and human activities. (3) The runoff of each subbasin will exhibit anti-persistent features with different persistence times in the future. (4) Compared with those in the baseline period, in the first measurement period, precipitation was the main factor driving the runoff increase in the Ganjiang, Fuhe, Xinjiang and Raohe subbasins, with contribution rates of 50.91–63.47%, and human activities played a supplementary role. However, in the second measurement period, as human activities intensified, they became the leading factor causing changes in runoff, with contribution rates between 59.57% and 92.49%. Considering water shortages and the intensification of human activities, the impacts of human activities on runoff variations will require more attention in the future.

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Water demand and the water shortage crisis are increasing worldwide due to the population and rapid growth of the global economy, which are becoming very serious social and environmental problems [1]. According to the World Health Organization, by the year 2025 approximately 50% of the world's population will live in water-stressed regions. Therefore, other alternative methods (utilizing desalted seawater or recycling wastewater) have been invented for efficient water consumption [2]. Desalination of seawater is Pol. AbstractDesalination of seawater is an effective way to alleviate the world's water shortage. However, the transmission and health risk of trace metals in the different processes of seawater plants are highly uncertain. Here, we investigated the concentrations of 29 ions and trace elements in desalinated water based on two desalination techniques -multiple effect distillation (MED) and reverse osmosis (RO)and evaluated the potential health risks (carcinogenic risk (CR) and non-carcinogenic risk (n-CR)) of trace metals in these processes. The results showed that most ions and trace elements were efficiently removed using both the RO and MED methods. After desalination, the trace metal concentrations in the desalinated water treated with the MED method were higher than those in the desalinated water treated with the RO method. The n-CR values for the trace metals in the desalinated water using the MED and RO methods were within the neglectable level. The CR values based on the two methods were lower than the maximal acceptable risk levels designated by the US Environmental Protection Agency. The total health risks using the MED method were higher than those using the RO method. Our results indicated that seawater desalination using both treatment methods is safe.