PAM对不同坡度坡地产流产沙及氮磷流失的影响

聚丙烯酰胺(PAM)是一种高效土壤改良剂,能影响土壤入渗、产流及溶质迁移、淋失.通过人工模拟降雨试验,研究了5°、15°和25°3个坡度水平下PAM对黄土高原沟壑区黑垆土坡地土壤侵蚀及氮磷流失情况的影响.结果显示:施加PAM后增加了5°和15°坡面的总产流量却减少了25°坡面的总产流量;PAM组初始产沙量较大,8 min以后,施加PAM组与对照组产沙速率出现差异并开始降低,表明施用PAM的起作用时间约为8~10 min,5°、15°和25°3个坡度的减沙率分别为38.2%、3.7%和53.9%.PAM对3个坡度径流中磷浓度有减小作用且不受坡度变化的影响,对5°和15°坡面铵态氮浓度影响不明显,但对25°坡面铵态氮浓度有明显减小作用,此外,PAM的施用能降低铵态氮初始流失浓度.施加PAM能影响土壤水分的再分配过程并减少3个坡度坡面硝态氮和磷的向下淋失.施加PAM后,5°、15°和25°坡面磷流失总量显著减少,减小幅度分别为77.6%、64.5%和85.1%;径流硝态氮流失总量随着坡度的增加先增加后减少,在15°~20°之间存在改变PAM对硝态氮影响作用的转折坡度值,PAM处理后的硝态氮流失量与径流量在0.05水平上显著相关,相关系数为0.998;PAM能够显著减少陡坡25°坡面溶解态铵态氮的流失量,减少幅度为60.1%.该项研究结果可为当地PAM的合理有效施用和提高水分及养分利用率提供科学指导.     

侵蚀条件下土壤氮素流失对土壤和环境的影响

土壤侵蚀严重地影响土壤物理和化学性质,限制了作物生产;它对作物生产具有长期和短期效应,短期效应通过施肥和培肥土壤等措施可得到恢复,而长期效应在较短时间内很难得到弥补。土壤氮素随径流流失不仅造成土壤肥力退化,而且对人类生存的自然环境造成危害。     

论江西洪涝灾害

在调查研究的基础上 ,依据大量历史资料 ,对建国 50 a年来江西洪涝灾害发生的类型、面积及其造成的严重损失进行了分析 ,并提出了防御洪涝灾害的对策和措施 ,对减轻江西洪涝灾害 ,实现全省农业跨世纪的持续发展具有指导意义     

Use of amendments to reduce leaching loss of phosphorus and other nutrients from a sandy soil in Florida

Goal, Scope and Background Transport of P from agricultural land contributes to the eutrophication of surface waters. Soil amendment is considered one of the best management practices (BMPs) to reduce P loss from sandy soils. Laboratory column leaching experiments were conducted to evaluate the effectiveness of different soil amendments in reducing P leaching from a typical sandy soil in Florida. Methods The tested amendments were CaCl₂, CaCO₃, Al(OH)₃, cellulose, and mill mud, and applied at the rate of 15 g/kg for a single amendment and each 7.5 g/kg if two amendments were combined. Leaching was conducted every four days for 32 days, 250 mL of deionized water being leached for each column per leaching event. Leachates were collected from each leaching event and analyzed for reactive P, PO₄-P, and macro and micro-elements. Results and Discussion Except for the soils amended with CaCl₂, or CaCl₂+CaCO₃, reactive P and PO₄-P leaching losses mainly occurred in the first three leaching events. Phosphorus leaching from the soils amended with CaCl₂ or CaCl₂+CaCO₃ was less but more persistent than that of other amendments. Reactive Pleaching loss was reduced by 36.0% and 40.4% for the amendments of CaCl₂, and CaCl₂+CaCO₃, respectively, as compared with chemical fertilizer alone, and the corresponding values for PO₄-P were 70.8% and 71.9%. The concentrations of K, Mg, Cu, and Fe in leachate were also decreased by CaCl₂ or CaCl₂+CaCO₃ amendment. Among the seven amendments, CaCl₂, CaCO₃, or their combination were most effective in reducing P leaching from the sandy soil, followed by cellulose and Al(OH)₃, the effects of mill mud and mill mud + Al(OH)₃ were marginal. Conclusions These results indicate that the use of CaCl₂, CaCO₃, or their combination can significantly reduce P leaching from sandy soil, and should be considered in the development of BMPs for the sandy soil regions. Recommendations and Outlook Most agricultural soils in south Florida are very sandy with minimal holding capacities for moisture and nutrients. Repeated application of fertilizer is necessary to sustain desired yield of crops on these soils. However, eutrophication of fresh water systems in this area has been increasingly concerned by the public. Losses of P from agricultural fields by means of leaching and surface runoff are suspected as one of the important non-point contamination sources. The benefits and effectiveness of soil amendment in reducing P losses from cropping production systems while sustaining desired crop yield need to be demonstrated. Calcium chloride, CaCO₃, or their combination significantly reduce Pleaching from sandy soil, and should be considered in the development of BMPs for the sandy soil regions.     

Effluent impact assessment using microarray-based analysis in common carp: a systems toxicology approach

Effluents are a main source of direct and continuous input of pollutants to the aquatic environment, and can cause ecotoxicological effects at different levels of biological organization. Since gene expression responses represent the primary interaction site between environmental contaminants and biota, they provide essential clues to understand how chemical exposure can affect organismal health. The aim of the present study was to investigate the applicability of a microarray approach for unraveling modes of action of whole effluent toxicity and impact assessment. A chronic toxicity test with common carp (Cyprinus carpio) was conducted where fish were exposed to a control and 100% effluent for 21 days under flow-through conditions. Microarray analysis revealed that effluent treatment mainly affected molecular pathways associated with the energy balance of the fish, including changes in carbohydrate and lipid metabolism, as well as digestive enzyme activity. These gene expression responses were in clear agreement with, and provided additional mechanistic information on various cellular and higher level effects observed for the same effluent. Our results demonstrate the benefit of toxicogenomic tools in a “systems toxicology” approach, involving the integration of adverse effects of chemicals and stressors across multiple levels of biological complexity.     

Large net forest loss in Cambodia’s Tonle Sap Lake protected areas during 1992–2019

Historical land-use practices have caused forest loss in Cambodia’s Tonle Sap Lake area (TSLA), the largest freshwater lake in Southeast Asia. However, it remains unclear if this deforestation trend had continued since 2001 when the land was designated as protected areas. Using satellite imagery, we investigated forest conversion flows and fragmentation patterns in the TSLA for 1992–2001, 2001–2010, and 2010–2019, respectively. Results show substantial forest losses and fragmentations occurring at the lower floodplain where the protected areas are located until 2010, with some forest regain during 2010–2019. The land conversions indicated that forest clearing and agricultural farming were the primary causes for observed extensive forest loss during 1992–2010. Hence, despite the creating of protected areas in 2001, our findings reveal the persistence of alarming forest loss in the TSLA until 2010. On the other hand, while net forest loss has stopped after 2010, forest regain during 2010–2019 is way too small to restore the region’s total forest area to even the level when the protected areas were established. Thus, more effective planning and implementations of forest management and restoration policies are needed for the TSLA.Supplementary InformationThe online version contains supplementary material available at 10.1007/s13280-022-01704-4.     

基于GIS与QuickBird影像的小流域土壤侵蚀定量评价

基于GIS技术和QuickBird遥感影像,采用修正的通用土壤流失方程RUSLE作为评价模型,计算了清水沟小流域土壤侵蚀量,并结合土壤侵蚀强度分级标准,生成流域土壤侵蚀强度等级图;利用GIS的叠置分析功能,定量分析了土壤侵蚀与坡度和土地利用之间的关系,并针对不同水保措施预测了水土保持治理效果.结果表明清水沟小流域土壤侵蚀模数为75.02 t·hm-2·a-1,属强度侵蚀区,年水土流失量2.6×104 t;流域64.5%的泥沙来自于占流域面积仅28%的极强度和剧烈侵蚀区域;经分析,流域土壤侵蚀模数与坡度呈显著正相关,不同土地利用类型的土壤侵蚀模数大小排序依次为难利用地＞建设用地＞坡耕地＞园地＞草地＞林地;退耕还林是降低土壤侵蚀强度与减少水土流失量的主要途径.     

环境损失与环境成本评估研究进展、问题及展望

本文在对环境损失与环境成本的基本概念、环境成本评估理论国内外研究进展以厦目前国内外主要采用的环境损失评估方法进行概述分析的基础上,指出当前研究存在的问题,提出以后的研究方向。     

Effects of land use on phosphorus loss in the hilly area of the Loess Plateau, China

The hilly area of Loess Plateau has some of the highest soil erosion rates in the world, and serious soil erosion causes great losses of plant nutrients. As the most common land use in Loess Plateau, slope farmland contributed most of the erosion soils. This study was designed to examine the effects of land use and slope angle of farmland on phosphorus (P) loss in the hilly area of loess plateau. Farmland (FR), barrenland (BR), and four forest treantment (seabuckthorn+ poplar (SP), immature seabuckthorn (IS), mature seabuckthorn (MS), immature Chinese pine (ICP)) were the types of land use; 10, 15, 20, 25, 30 degrees were the slope angles of FR that were compared. The results showed a larger proportion of P loss occurred in erosion soil fraction of FR, ICP, ICP, and the five slope treatments of FR; in SP, IS, and MS, P loss was primarily through runoff. FR produced more P loss than SP, IS, ICP, BR, and MS. 20∼30 degrees may be the slope ranges for P loss of FR; FR in this ranges would loss more P with soil erosion. SP, IS, and MS were reasonable land uses for their less runoff, soil loss, and P loss. Farmlands over 15 degrees should be abandoned or reforested for it would produce more runoff, soil loss, and P loss.