作者机构:
[Wu, Jing; Yang, Xia; Peng, Bo; Peng, B; Wu, Sicheng; Chen, Haisheng; Guo, Xintong; Xie, Shurong; Fang, Xiaohong; Dai, Yanan] Hunan Normal Univ, Sch Geog Sci, Changsha 410081, Peoples R China.;[Wu, Jing; Yang, Xia; Peng, Bo; Peng, B; Wu, Sicheng; Chen, Haisheng; Guo, Xintong; Dai, Yanan] Hunan Normal Univ, Key Lab Environm Heavy Met Contaminat & Ecol Remed, Changsha 410081, Peoples R China.;[Fang, Xiaohong] Hengyang Normal Univ, Coll Geog & Tourism, Hengyang 421002, Peoples R China.;[Xie, Shurong] East China Univ Technol, Sch Earth Sci, Nanchang 330013, Peoples R China.
通讯机构:
[Peng, B ] H;Hunan Normal Univ, Sch Geog Sci, Changsha 410081, Peoples R China.;Hunan Normal Univ, Key Lab Environm Heavy Met Contaminat & Ecol Remed, Changsha 410081, Peoples R China.
摘要:
Terrestrial evapotranspiration (ET) refers to a key process in the hydrological cycle by which water is transferred from the Earth's surface to lower atmosphere. With spatiotemporal variations, ET plays a crucial role in the global ecosystem and affects vegetation distribution and productivity, climate, and water resources. China features a complex, diverse natural environment, leading to high spatiotemporal heterogeneity in ET and climatic variables. However, past and future ET trends in China remain largely unexplored. Thus, by using MOD16 products and meteorological datasets, this study examined the spatiotemporal variations of ET in China from 2000 to 2019 and analyzed what is behind changes, and explored future ET trends. Climate variation in China from 2000 to 2019 was statistically significant and had a remarkable impact on ET. Average annual ET increased at a rate of 5.3746 mm yr(-1) (P < 0.01) during the study period. The main drivers of the trend are increasing precipitation and wind speed. The increase in ET can also be explained to some extent by increasing temperature, decreasing sunshine duration and relative humidity. The zonation results show that the increase in temperature, wind speed, and precipitation and the decrease in relative humidity had large and positive effects on ET growth, and the decrease in sunshine duration had either promoting or inhibiting effects in different agricultural regions. Pixel-based variations in ET exhibited an overall increasing trend and obvious spatial volatility. The Hurst exponent indicates that the future trend of ET in China is characterized by significant anti-persistence, with widely distributed areas expected to experience a decline in ET. These findings improve the understanding of the role of climate variability in hydrological processes, and the ET variability in question will ultimately affect the climate system.
摘要:
Given environmental or hydrological functions influenced by changing river networks in the development of rapid urbanization, a clear understanding of the relationships between comprehensive urbanization (CUB) and river network characteristics (RNC), storage capacity (RSC), and regulation capacity (RRC) is urgently needed. In the rapidly urbanized Tai Lake Plain (TLP), China, various methods and multisource data were integrated to estimate the dynamics of RNC, RSC, and RRC as well as their interactions with urbanization. The bivariate Moran's I methods were applied to detect and visualize the spatial dependency of RNC, RSC, or RRC on urbanization. Geographically weighted regression (GWR) model was set up to characterize spatial heterogeneity of urbanization influences on RNC, RSC and RRC. Our results indicated that RNC, RSC and RRC variables each showed an overall decreasing trend across space from 1960s to 2010s, particularly in those of tributary rivers. RNC, RSC, or RRC had globally negative correlations with CUB, respectively, but looking at local scale the spatial correlations between each pair were categorized as four types: high-high, high-low, low-low, and low-high. GWR was identified to accurately predict the response of most RNC, RSC, or RRC variables to CUB (R-2: 0.6-0.8). The predictive ability of GWR was spatially non-stationary. The obtained relationships presented different directions and strength in space. All variables except for the water surface ratio (Wp) were more positively affected by CUB in the middle eastern parts of TLP. Drainage density, RSC and RRC variables were more negatively influenced by CUB in the northeast compared to other parts. The quantitative results of spatial relationships between urbanization and RNC, RSC or RRC can provide location-specific guidance for river environment protection and regional flood risk management.
作者机构:
[钟顺清] Department of Resource Environment and Tourism Management, Hengyang Normal University, Hengyang 421008, Hunan, China;Institute of Soil and Water Resource and Environmental Science, Zhejiang University, Hangzhou 310058, China;Zhejiang Province Key Laboratory of Subtropic Soil and Plant Nutrition, Hangzhou 310058, China;[徐建明] Institute of Soil and Water Resource and Environmental Science, Zhejiang University, Hangzhou 310058, China, Zhejiang Province Key Laboratory of Subtropic Soil and Plant Nutrition, Hangzhou 310058, China
通讯机构:
[Xu, J.-M.] I;Institute of Soil and Water Resource and Environmental Science, , Hangzhou 310058, China
摘要:
Constructed wetlands have emerged as a viable option for helping to solve a wide range of water quality problems. However, heavy metals adsorbed by substrates would decrease the growth of plants, impair the functions of wetlands and eventually result in a failure of contaminant removal. Typha latifolia L., tolerant to heavy metals, has been widely used for phytoremediation of Pb/Zn mine tailings under waterlogged conditions. This study examined effects of iron as ferrous sulfate (100 and 500 mg/kg) and lead as lead nitrate (0, 100, 500 and 1000 mg/kg) on phosphorus utilization and microbial community structure in a constructed wetland. Wetland plants (T. latifolia) were grown for 8 weeks in rhizobags filled with a paddy soil under waterlogged conditions. The results showed that both the amount of iron plaque on the roots and phosphorus adsorbed on the plaque decreased with the amount of lead addition. When the ratio of added iron to lead was 1:1, phosphorus utilized by plants was the maximum. Total amount of phospholipids fatty acids (PLFAs) was 23%–59% higher in the rhizosphere soil than in bulk soil. The relative abundance of Gram-negative bacteria, aerobic bacteria, and methane oxidizing bacteria was also higher in the rhizosphere soil than in bulk soil, but opposite was observed for other bacteria and fungi. Based on cluster analysis, microbial communities were mostly controlled by the addition of ferrous sulfate and lead nitrate in rhizosphere and bulk soil, respectively.