近25年三峡库区土地覆被变化及驱动力分析

基于1990、2000、2005、2010和2015年五期30 m空间分辨率土地覆被遥感数据,利用动态度模型和转移矩阵,综合分析了近25 a三峡库区土地覆被的时空格局、变化特征及驱动力。研究结果表明：2015年三峡库区土地覆被以森林和耕地为主,分别占总面积的41.45%和24.58%;1990~2015年三峡库区人工表面、湿地、森林和其他用地的面积增长明显,耕地、灌丛和草地的面积整体减少,区域综合土地覆被动态度呈先增加后稳定的变化趋势,人工表面是最为活跃的土地覆被类型,其次是湿地和耕地;前10 a三峡库区人工表面占用耕地较为突出,后15 a土地覆被类型转换主要为森林、灌丛和耕地转为人工表面和湿地;三峡工程建设、移民安置与迁建、经济发展与城镇化导致人工表面不断扩张,水库蓄水导致湿地面积迅速增加,农业结构调整促使园地面积扩张。三峡库区近25 a来,在退耕还林等生态保护政策影响下,生态环境状况趋于改善,库区森林面积显著增加,坡耕地面积持续减少,但人地矛盾日益突出,研究结果可为后三峡时代库区生态环境保护与社会经济的协调发展提供数据支撑。     

Different exposure levels of fine particulate matter and preterm birth: a meta-analysis based on cohort studies

The previous studies estimated the association between PM_2.5 (particulate matter with aerodynamic diameter less than or equal to 2.5 μm) exposure during pregnancy and preterm birth, only considered and highlighted the hazard effects of high levels of air pollutant exposure, and underestimated that low levels of pollutant exposure might also affect pregnancy outcome. We conducted a meta-analysis of 11 cohort studies, a total of more than 1,500,000 subjects. The results of these studies were pooled by exposure levels and study periods. PM_2.5 exposure during pregnancy was positively associated with preterm birth (OR = 1.15, 95% CI = 1.07–1.23), and during the first trimester of pregnancy, low levels of PM_2.5 exposure were also positively associated with preterm birth (OR = 1.17, 95% CI = 1.04–1.30). It is important to protect pregnant women from PM_2.5 exposures, especially during their first trimester of pregnancy even when the ambient PM_2.5 concentration is relatively low. More relevant health policy should be carried out to prevent hazard effect of air pollutants.     

Study on substrate metabolism process of saline waste sludge and its biological hydrogen production potential

With the increasing of high saline waste sludge production, the treatment and utilization of saline waste sludge attracted more and more attention. In this study, the biological hydrogen production from saline waste sludge after heating pretreatment was studied. The substrate metabolism process at different salinity condition was analyzed by the changes of soluble chemical oxygen demand (SCOD), carbohydrate and protein in extracellular polymeric substances (EPS), and dissolved organic matters (DOM). The excitation-emission matrix (EEM) with fluorescence regional integration (FRI) was also used to investigate the effect of salinity on EPS and DOM composition during hydrogen fermentation. The highest hydrogen yield of 23.6 mL H₂/g VSS and hydrogen content of 77.6% were obtained at 0.0% salinity condition. The salinity could influence the hydrogen production and substrate metabolism of waste sludge.

     

Applications of vacuum sealing drainage in treating seawater-immersed sulfur mustard injury

Vacuum sealing drainage has excellent therapeutic effects on the complex injuries. There is no relevant report on seawater-immersed sulfur mustard injury. The treatment effects were examined with miniature pigs. Injuries were performed on their back followed by vacuum sealing drainage at various pressures for nine days. Injured tissues were sampled up to 30 d after treatment and healing rates, levels of interleukin-6, tumor necrosis factor α, and vascular endothelial growth factor were recorded. Vacuum sealing drainage enhances the healing of sulfur mustard wounds significantly, reduces the interleukin-6 and tumor necrosis factor α levels in the wound, and increases the vascular endothelial growth factor expression. Pressure reduction by 180 mmHg is the most suitable condition for vacuum treatment.     

NO oxidation over Co-La catalysts and NO<Subscript><Emphasis Type="Italic">x</Emphasis></Subscript> reduction in compact SCR

A series of Co-La catalysts were prepared using the wet impregnation method and the synthesis of catalysts were modified by controlling pH with the addition of ammonium hydroxide or oxalic solution. All the catalysts were systematically investigated for NO oxidation and SO₂ resistance in a fixed bed reactor and were characterized by Brunanuer–Emmett–Teller (BET) method, Fourier Transform infrared spectroscopy (FTIR), X–ray diffraction (XRD), Thermogravimetric (TG) and Ion Chromatography (IC). Among the catalysts, the one synthesized at pH = 1 exhibited the maximum NO conversion of 43% at 180°C. The activity of the catalyst was significantly suppressed by the existence of SO₂ (300 ppm) at 220°C. Deactivation may have been associated with the generation of cobalt sulfate, and the SO₂ adsorption quantity of the catalyst might also have effected sulfur resistance. In the case of the compact selective catalytic reduction (SCR), the activity increased from 74% to 91% at the highest gas hourly space velocity (GHSV) of 300000 h^–1 when the NO catalyst maintained the highest activity, in excess of 50% more than that of the standard SCR.

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The dissipation and risk assessment of 2,4-D sodium,a preharvest anti-fruit-drop plant hormone in bayberries

Preharvest fruit-drop is a challenge to bayberry production. 2,4-D sodium as a commonly used anti-fruit-drop hormone on bayberry can reduce the yield loss caused by preharvest fruit-drop. The persistence and risk assessment of 2,4-D sodium after applying on bayberries were investigated. A method for determining 2,4-D sodium in bayberry was established based on LC-MS-MS. The average recoveries of 2,4-D sodium were at the range of 93.7–95.8% with relative standard deviations (RSDs) ranging from 0.9 to 2.8%. The dissipation rates of 2,4-D sodium were described using first-order kinetics, and its half-life ranged from 11.2 to 13.8 days. A bayberry consumption survey was carried out for Chinese adults for the first time. The safety assessments of 2,4-D sodium were conducted by using field trail data as well as monitoring data. Results showed that the chronic risk quotient and the acute risk quotient were calculated to be 0.23–0.59 and 0.02–0.05%, respectively, for Chinese adults, indicating low dietary risk for adults and children. In the end, the household cleaning steps were compared, and results showed that water rinsing for 1 min can remove 49.9% 2,4-D sodium residue, which provides pesticide removal suggestion for consumers.

     

碳材料促进废水厌氧处理中直接种间电子传递的研究进展

直接种间电子传递(DIET)是近年来发现的一种微生物电子传递方式,其在废水厌氧生物处理的重要过程中起重要作用。提高DIET效率能在促进有机物厌氧降解产甲烷的同时储存更多能量,优化厌氧生物处理工艺性能并降低处理成本。本文在DIET过程特性分析的基础上,重点论述了活性炭、生物炭、碳纤维布、单壁碳纳米管4种碳材料对废水生物处理中DIET过程的促进作用,并对今后的研究方向进行了展望。     

关于构建企业环境守法引导机制框架的思考

当前我国经济发展步入新常态阶段,经济发展速度减慢,部分企业资金缩紧,难免出现逃避监管、偷排漏排等现象。在这种形势下,只有转变对企业的传统监管模式,从单纯的行政执法向行政执法与守法激励相结合模式转变,建立企业环境守法引导机制,才能更好、更快地促进企业自觉调整结构,创新技术,发展绿色产业,从而实现环境效益、经济效益和社会效益共赢。本研究基于环境规制、利益相关者以及企业社会责任等理论基础,提出构建企业环境守法引导机制的基本框架由行政监管、经济激励、企业自律和社会监督等四个方面构成,并分析目前我国企业环境守法引导机制建设存在不完善问题,建议从完善行政监管执法机制、健全经济激励政策、加强企业环保意识培养、完善社会监督机制等方面间接和直接引导企业环境守法。     

长江中游城市群网络联系度与度中心性时序变化研究(2001～2016)

长江中游城市群在国家发展中的作用越来越突出,其网络化的城市体系也逐渐发育并趋于完善.充分考虑到经济、人口、贸易、运输量、基础设施、公共服务等多种因素,并基于时间序列上的考量,从传统引力模型出发,引入克鲁格曼指数,通过AHP法,确定经济、社会2个维度的城市"质量"以及几何直线、公路、铁路3个维度的城市联系成本等各个模型指标的权重,研究了长江中游城市群2001～2016年的城市联系度和度中心性的时序变化.研究发现,随着经济社会的发展以及城市间联系通道的建设,以武汉-长沙-南昌为中心的长江中游城市群城市联系网络体系逐渐形成并不断深化,以武汉、长沙为中心的城市群体发挥着越来越重要的作用,对区域的影响力逐渐强化,越来越多的城市融入到城市网络中,并发展均衡.研究表明:(1)区域网络化特征越来越显著,联系深化逐渐显现,构建区域联系大通道、促进基础设施互联互通十分重要.(2)中心城市显著加强,次级节点的培育有待提高,多中心、层级化、深层次的城市体系渐渐形成,还需要强化顶层、开拓底层配合发挥作用.(3)网络化与层级化的长江中游城市群正在完善,创新、协调、绿色、开放、共享的城市体系既需要中心城市的引领,也需要更多城市积极深入、积极参与、积极推进.     

苎麻脱胶废水喷淋锅炉烟气除尘脱硫降碱的实验研究

利用苎麻脱胶碱性废水喷淋锅炉烟气,可降低烟气中的粉尘、SO₂;采用中和碱性废水可节省原水膜除尘所耗的自来水。结果表明,碱性废水喷淋烟气对SO₂的脱除率是自来水喷淋效果的40倍,粉尘去除率高于自来水喷淋的33％,COD下降18％。为造纸、制药、印染等企业提供了碱性废水前处理新工艺。