关键词：
Dongting Lake;East;Ecological response;Hydrological regime change;Three Gorges Dam
摘要：
Extent, frequency and duration of lake water level fluctuations (WLF) are dominant forces controlling the functioning of lake ecosystems, especially in the lake's littoral and aquatic-terrestrial interface processes. In East Dongting Lake, Carex life history synchronize the arrival of overwintering birds, Carex meadow provide vital wintering ground for migratory waterbirds, especially for the Lesser White-fronted Geese. However, significant changes had taken place in the hydrological regime of East Dongting Lake and our research showed it caused chiefly by sediment deposition in the lake basin and the replenishment of the Three Gorges Dam. The annual lowest water level of the East Dongting Lake had gradually risen and the annual water level amplitude had decreased obviously over the past 60 years. Since the operation of the Three Gorges Dam, the average water level increased significantly from January to June. The Three Gorges Dam holder the incoming water from late September to late October that the status will change from flood control limited water level to normal water level, meanwhile the water level of East Dongting Lake declined significantly through the same duration, especially in October. The operation of the Three Gorges Dam decreased flooding days in the areas above 22-m elevation, resulting in lowering of the minimum elevation of vegetation-covered area and synchronous downward movement of vegetation distribution pattern. As the timing of water level recession at elevations of 24-27 m were 12, 17, 19 and 16 days earlier than that in 1981-2002, the optimum elevation for Carex growth decreased from 25-26 m to 24-25 m. After the operation of the Three Gorges Dam, the annual reversal times of water level increased significantly, which is not conducive to the formation of stable habitat and the utilization of resources by organisms. (C) 2019 European Regional Centre for Ecohydrology of the Polish Academy of Sciences. Published by Elsevier B.V. All rights reserved.
关键词：
Heavy metal;Oil crop;Organic acid;Phytoremediation;Rhizosphere soil;pH
摘要：
The physico-chemical characteristics of N fertilizers remain poorly understood with respect to their use with rape (Brassica napus L.) to remediate Cd-contaminated soil. In this work, eight types of fertilizer (comprising physico-chemical alkaline, neutral, and acidic N fertilizers) were employed to assess the effect of soil remediation via rape at different levels of Cd contamination (0, 5, and 10 mg kg(-1) Cd). The results show that the pH of rhizosphere soils was significantly higher under physico-chemical alkaline N fertilizer treatments than under physico-chemical acidic and neutral N fertilizer treatments. The physico-chemical characteristics of N fertilizers affected the rhizosphere soil pH and promoted Cd phytoextraction and accumulation by rape. In the 5 mg kg(-1) Cd-contaminated soil, the Cd accumulation and bioconcentration factor value in the shoots and the Cd translocation factor value were highest with the addition of NH4Cl, a physico-chemical acidic N fertilizer. Among the physico-chemical alkaline N fertilizers, Ca(NO3)2 enabled the highest accumulation of Cd in rape shoots when soil was contaminated with 10 mg kg(-1) Cd. Thus, administering physico-chemical acidic N fertilizer to soils with lower Cd concentrations provides better remediation effects by rape, whereas physico-chemical alkaline N fertilizers are more effective in soils with higher Cd concentrations. These results show that physico-chemical N fertilizers can be employed to enhance the remediation of Cd-contaminated soil by rape and simultaneously improve the yield of this crop, with implications for environmental health and sustainable agricultural development.
作者机构：
[吴爱平; 邹冬生; 李有志] Hunan Provincial Key Laboratory of Rural Ecosystem Health in Dongting Lake Area, College of Bioscience and Biotechnology, Hunan Agricultural University, Changsha, 410128, China;[郑华] State Key Laboratory of Urban and Regional Ecology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing, 100085, China;[张凯] College of Grassland and Environment Sciences, Xinjiang Agricultural University, Urumqi, 830052, China;[向丹] College of Resources and Environment, Qingdao Agricultural University, Qingdao，Shandong266109, China;[陈法霖] Hunan Provincial Key Laboratory of Rural Ecosystem Health in Dongting Lake Area, College of Bioscience and Biotechnology, Hunan Agricultural University, Changsha, 410128, China, State Key Laboratory of Urban and Regional Ecology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing, 100085, China
通讯机构：
[Zheng, H.] S;State Key Laboratory of Urban and Regional Ecology, China
摘要：
Emerging contaminants have recently been recognized as new and significant water pollutants and gained great of concerns because of their considerable effects on ecosystems and human health. Current conventional wastewater treatment technologies are not efficient at removing these trace contaminants: novel and lower cost approaches are required. Biochar is well-known as an effective adsorbent for the removal of complex inorganic contaminants and organic contaminants from water. This review provides a summary of recent research on the underlying mechanisms controlling the presence of emerging contaminants in water, as well as their removal and the environmental treatment of soil by biochar. A range of information is also presented regarding the application of this resource: it is clear that a variety of cheap, efficient, modified, and composite biochar that is able to remove emerging contaminants will be required to further advance research progress. (C) 2018 Elsevier Ltd. All rights reserved.
摘要：
Successful phytoextraction produces a large quantity of contaminated biomass, which will cause secondary pollution unless properly treated. This study investigated the disposal of contaminated tobacco biomass after phytoextraction. We detected significantly high Cadmium concentrations in tobacco, especially in their stems and leaves. From the latter, nearly all the Cd and nicotine were removed by extractions with 0.5% HCl + 70% ethanol, and the nicotine completely recovered via steam distillation, whereas the protein content remained unaffected in the leaves, thus making them safe for use as animal feed. The highest biochar yield was 47%, obtained after slow pyrolysis at 300 degrees C. In this case, the biochar contained the highest amount of nutrients and metals. From stem biochar, 87% of Cd and a large amount K along with several other elements were extracted by deionized water at pH 1. After acid-extraction, metals were formed precipitation and then separated from the K-enriched solution when the pH was adjusted to 11 by using drops of 40% KOH. Therefore, with improved technology to remove metals and recover nutrients and nicotine from biomass, tobacco is an ideal candidate as profit yielding crop for use in phytoextraction while also providing renewable resources.
摘要：
Beta diversity describes the variation in species composition between sites and is often influenced by both local and regional processes. Partitioning beta diversity into turnover (species replacement between sites) and nestedness (richness difference between sites) components may enhance our understanding of the mechanisms behind the local and regional drivers determining species composition across spatial scales. We sampled macrophyte communities in 24 lakes in two regions (Yangtze River basin and Yunnan-Guizhou plateau) of China covering broad climate and nutrient gradients. Based on both species and functional approaches, we calculated multiple-site beta diversity using the Sorensen dissimilarity index and partitioned it into turnover and nestedness coefficients crossed with two nested spatial scales: among depths within transects (transect scale) and among transects within lakes (lake scale). The overall species beta diversity and functional beta diversity (i.e. Sorensen coefficient) were significantly lower and thus more homogeneous at lake scale. Across spatial scales, species beta diversity was mainly explained by turnover patterns (56-61%) and functional beta diversity primarily by nestedness patterns (58-65%). Both local and regional drivers contributed to structuring species and functional beta diversity patterns, largely through changes in species turnover and functional nestedness, respectively. Overall, we observed a significant increase in species beta diversity and its turnover component while a decreasing trend in functional beta diversity and its nestedness component at high altitude. Our results further emphasized that the species beta diversity and its turnover component decreased at high total phosphorus concentration (TP) across the two spatial scales, while the functional beta diversity and its nestedness component decreased at high TP at the transect scale. We conclude that understanding of the relative role of local and regional drivers in determining macrophyte diversity patterns may help managers to select the most appropriate conservation strategies for preservation of biodiversity varying with the scale in focus.
通讯机构：
Key Laboratory for Agro-ecological Processes in Subtropical Region, Institute of Subtropical Agriculture, Chinese Academy of Sciences, Changsha, China
