Estimation on wetland loss and its restoration potential in Modern Yellow River Delta,Shandong Province of China

Wetland is one of the most important ecosystems with varied functions and structures, and its loss has been a major issue. Wetland loss in Modern Yellow River Delta (MYRD) becomes a serious environmental problem, so its restoration attracts a great deal of attention from academia and governments. This article proposes a GIS-based multi-criteria comprehensive evaluation methodology for potential estimation of wetland restoration, using MYRD as an example. The model uses four kinds of data (hydrology, terrain, soil, and land use) and could be adapted by planners for use in identifying the suitability of locations as wetland mitigation sites at any site or region. In the application of the model in the MYRD, the research developed a lost wetland distributed map taking the better wetland situation of 1995 as the reference, and elevated the overall distribution trends of wetland restoration potential based on wetland polygon. The results indicated that the total area of wetland loss from 1995 to 2014 was 568.12 km², which includes 188.83 km² natural wetland and 21.80 km² artificial wetland, respectively. The areas of lost wetland with low, middle, and high resilience ability are 126.82 km², 259.92 km², and 119.59 km², occupying 25.05%, 51.33%, and 23.62%, respectively. The high-restoration-potential wetland included 98.47 km² of natural wetland and 21.12 km² of artificial wetland, which are mainly bush, reed, and ponds. The high-restoration-potential wetland is mainly distributed in the vicinity of Gudong oil field, the Yellow River Delta protected areas, and the eastern sides of Kenli county and Dongying city.     

Irrigation water quality and the benefits of implementing good agricultural practices during tomato (Lycopersicum esculentum) production

The implementation of good agricultural practices (GAP) from irrigation water to the tomato packaging process enhances the safety of fresh produce and its value throughout the food chain. The aim of the present study was to show that fresh produce farms that apply and enforce GAP could reduce the presence of Salmonella in finished produce. Samples were collected biweekly from six packing houses from the central region of Sinaloa, México, for the isolation of Salmonella spp by the ISO 6579:2002 method, and the isolated strains were serotyped and genotyped by the Kauffmman-White scheme and pulsed field gel electrophoresis (PFGE), respectively. Salmonella strains were detected in 13 (36.1 %) irrigation water samples, while only two tomato samples were positive (5.5 %). Eight different serotypes were identified in irrigation water, and Salmonella Oranienburg (34 %) was the most prevalent; however, only Salmonella Agona and Salmonella Weltevreden were present on tomatoes. Salmonella Oranienburg was the most widely dispersed and variable serotype, with 10 different PFGE profiles. Salmonella Weltevreden was isolated from both types of samples, albeit with distinct genetic profiles, implying that the sources of contamination differ. These results confirm the utility of implementing good agricultural practices to reduce Salmonella contamination in irrigation water and the packaging process.     

Isotopic evidence of natural uranium and spent fuel uranium releases into the environment

Uranium and plutonium isotopes were measured in soils, sediments and waters in an area subject to the past and present discharges from the uranium conversion plant of Malvési (France). The isotopes (236)U and (239)Pu are well known activation products of uranium and they prove to be powerful tracers of spent fuel releases in soils and sediments. On the other hand (234)U and (238)U activities measured in waters can be used to distinguish between releases and background uranium sources. Such findings contribute to improve the monitoring of the actinides releases by nuclear fuel facilities (mining sites, conversion, enrichment and fuel plants, reprocessing plants).     

微电网电压分层控制与补偿机制研究

微电网技术具有许多优点,然而微电网中的分布式电源自身的不稳定性会导致微电网的运行控制困难,特别是公共连接点处会出现电压不平衡。为了补偿此不平衡电压,提出了分层控制方法。该方法将电网运行控制分为.上下2层,由.上层控制发送控制信号,并由下层控制来实施,此控制信号与正序电压分量和负序电压分量有关;在dq旋转坐标下,依靠同步坐标系锁相环( SRF-PLL)和解耦的双同步坐标系锁相环(DDSRF-PLL)等并网同步技术将微电网同步地接入电网,并通过控制逆变器得到电压幅值。仿真结果表明:分层控制方法能够较好地实现对微电网的控制。     

Application of WRF-Chem to simulate air quality over Northern Vietnam

Environmental Science and Pollution Research - The WRF-Chem (Weather Research and Forecasting with Chemistry) model is implemented and validated against ground-based observations for meteorological...     

Degradation of 2,4,6-trichlorophenol in aqueous systems through the association of zero-valent-copper-mediated reduction and UVC/H2O2: effect of water matrix and toxicity assessment

Environmental Science and Pollution Research - The presence of toxic chlorinated compounds in drinking water, generated during the disinfection step in water treatment plants, is of great concern...     

石羊河流域降水稳定同位素变化的区域差异

为了了解干旱内陆河流域降水稳定同位素变化过程及其影响因素,基于石羊河流域荒漠区、绿洲区和山区8个站点2013年7月至2014年7月,497个降水样品氢氧稳定同位素数据及相应气象数据,研究了石羊河流域降水稳定同位素的时空变化、环境效应以及降水水汽来源.结果显示：石羊河流域局地大气水线斜率和截距表现出夏低冬高的变化趋势;降水稳定同位素表现出夏高冬低的变化趋势,从荒漠区、绿洲区到山区,稳定同位素值随海拔升高而降低,海拔效应为-0.22‰/100m,这是温度效应的另一种体现;流域降水稳定同位素表现出显著的温度效应,温度效应为0.43‰/℃,在天气尺度下受季风水汽和降水淋洗过程的影响表现出降水量效应;流域降水来源主要受西风水汽控制,夏季也会会受到季风水汽影响,冬季也受到极地气团影响.     

微生物对冰封期湖泊沉积物中有机磷降解释放的影响

以寒旱区湖泊乌梁素海为研究对象,以有机磷降解过程中的形态转化为主线,探讨了冰封期内底物添加与灭菌处理对有机磷释放特征的影响.结果表明,180 d冰封期内,灭菌处理(T_N)上覆水中可溶性总磷酸盐(DTP)和可溶性正磷酸盐(DIP)及可溶性有机磷(DOP)的质量浓度均高于底物添加处理(T_M),揭示T_M体系中厌氧微生物的同化利用降低了上覆水中磷的质量浓度;同时微生物驱动下铁的异化还原作用也是影响水-沉积物界面有机磷释放的重要机制.释放周期内,沉积物中活性有机磷(LOP)、总活性磷(TLP)的含量均减少;T_M体系的中等活性有机磷(MLOP)含量先减少后增加,非活性有机磷(NLOP)的含量先增加后减少;T_N的MLOP含量波动性增加,NLOP的含量波动性减少.释放初期(0~60 d),T_M的MLOP含量高于T_N,而NLOP的含量低于T_N;释放中末期(60~180 d),T_M的MLOP含量低于T_N,而NLOP的含量高于T_N.揭示释放中沉积物MLOP与NLOP之间存在相互转化的可能性.释放过程中,T_M沉积物有机磷的相对含量降低,无机磷的相对含量增高,呈现有机磷向无机磷转化的趋势,沉积物有机磷约有6.1%转化为无机磷,揭示了冰封期内,微生物可加速沉积物有机磷向无机磷的转化,提高了磷的生物可利用率,增加了沉积物磷向上覆水释放的风险.