不同养殖模式池塘沉降颗粒营养物质组成特征

2012年4~10月采用自制沉降颗粒收集装置收集主养草鱼和黄颡鱼池塘生态系统中沉降颗粒物,开展了颗粒物质的垂直沉降量以及沉降颗粒中碳氮磷等营养物质的组成及沉降通量的季节变化特征的研究。结果表明:养殖可以显著提高池塘颗粒物质的垂直沉降量,主养草鱼池塘中颗粒物质垂直沉降量显著高于主养黄颡鱼池塘(p0.01),且两种养殖模式池塘颗粒物质沉降量随着养殖时间推进有显著增加的趋势。主养草鱼的池塘中颗粒物质垂直沉降量在100.39~414.66g/(m2·d)之间变化,平均为224.46g/(m2·d),主养黄颡鱼池塘中沉降颗粒物质垂直沉降量在34.14~272.91g/(m2·d)之间变化,平均为155.18g/(m2·d)。两种养殖模式沉降颗粒的碳氮磷成分在养殖周期内的变化规律不明显但具有相似的变化趋势,主养黄颡鱼池塘沉降颗粒中TN、TC、TOC和TON的含量均比同时期主养草鱼高,且均随着养殖时间的推进,沉降颗粒中碳氮磷的总量呈增加趋势。两种养殖模式池塘沉降颗粒中的C/N比值与沉积物中的C/N比值较为接近,表明沉降颗粒与沉积物营养物质来源具有一定的相似性,同时养殖系统内养殖对象与其所处环境的相互依存和相互影响对颗粒物质的产生以及沉降具有重要作用。     

可燃物化学性质对燃烧释放PM2.5元素成分的影响

通过自主设计的燃烧装置,对云南省6种典型乔木树种的不同器官(枝、叶、皮)室内模拟阴、明燃两种燃烧过程,收集燃烧排放颗粒物(PM_2.5)并测定K、Mg等8种元素排放因子,比较不同燃烧状态释放PM_2.5中元素含量的差异,同时分析各元素排放因子与可燃物自身元素含量之间的相关性.结果表明:可燃物中K、Mg和Ca元素含量较高,范围为(137.74~4670.70) mg/kg,微量元素Mn含量突出;阔叶可燃物元素含量普遍高于针叶,器官间元素含量差异显著;燃烧释放PM_2.5中K、Na元素排放因子较高,范围为(0.4269~4.9321)~(0.6311~3.0856) mg/kg,微量元素Zn较高、Cu最少,范围为(0.0409~0.3670)~(0.0029~0.0458) mg/kg,常量元素高于微量;树种间元素排放因子表现针叶高于阔叶,器官间较可燃物自身差异增大;燃烧状态对排放因子存在影响,常量元素普遍表现为明燃>阴燃,微量元素无明显规律;PM_2.5与可燃物各元素含量比值中,Na元素最高,其余元素占比普遍0~1%范围,微量元素含量比高于常量,针叶高于阔叶;可燃物的化学性质对其排放特性影响显著,可燃物与PM_2.5的元素间相关性较高,相关水平普遍达0.600以上,器官间不同元素相关水平表现为:常量元素普遍高于微量元素,针叶略高于阔叶,叶>皮>枝,明燃高于阴燃.     

Dosing low-level ferrous iron in coagulation enhances the removal of micropollutants, chlorite and chlorate during advanced water treatment

Drinking water utilities are interested in upgrading their treatment facilities to enhance micropollutant removal and byproduct control. Pre-oxidation by chlorine dioxide (ClO₂) followed by coagulation-flocculation-sedimentation and advanced oxidation processes (AOPs) is one of the promising solutions. However, the chlorite (ClO₂^–) formed from the ClO₂ pre-oxidation stage cannot be removed by the conventional coagulation process using aluminum sulfate. ClO₂^– negatively affects the post-UV/chlorine process due to its strong radical scavenging effect, and it also enhances the formation of chlorate (ClO₃^–). In this study, dosing micromolar-level ferrous iron (Fe(II)) into aluminum-based coagulants was proposed to eliminate the ClO₂^– generated from ClO₂ pre-oxidation and benefit the post-UV/chlorine process in radical production and ClO₃^– reduction. Results showed that the addition of 52.1-µmol/L FeSO₄ effectively eliminated the ClO₂^– generated from the pre-oxidation using 1.0 mg/L (14.8 µmol/L) of ClO₂. Reduction of ClO₂^– increased the degradation rate constant of a model micropollutant (carbamazepine) by 55.0% in the post-UV/chlorine process. The enhanced degradation was verified to be attributed to the increased steady-state concentrations of HO^· and ClO^· by Fe(II) addition. Moreover, Fe(II) addition also decreased the ClO₃^– formation by 53.8% in the UV/chlorine process and its impact on the formation of chloro-organic byproducts was rather minor. The findings demonstrated a promising strategy to improve the drinking water quality and safety by adding low-level Fe(II) in coagulation in an advanced drinking water treatment train.     

Identification of unknown disinfection byproducts in drinking water produced from Taihu Lake source water

Although disinfection byproducts(DBPs) in drinking water have been suggested as a cancer causing factor, the causative compounds have not yet been clarified. In this study, we used liquid chromatography quadrupole-time-of-flight spectrometry(LC-QTOF MS) to identify the unknown disinfection byproducts(DBPs) in drinking water produced from Taihu Lake source water, which is known as a convergence point for the anthropogenic pollutants discharged from intensive industrial activities in the surroundi...     

Water Management Applications for Satellite Precipitation Products: Synthesis and Recommendations

This article is an assessment of the current state of the art and relative utility of satellite precipitation products (SPPs) for hydrologic applications to support water management decisions. We present a review of SPPs, their accuracy in diverse settings including the influence of geography, topography, and weather systems, as well as the pros and cons of their use for different water management applications. At the end of this broad synthesizing effort, recommendations are proposed for: (1) SPP developers to improve the quality, usability, and relevance of precipitation products; and (2) SPP users to improve the reliability of their predictions and hydrologic applications to better support water management.     

复杂电磁环境仿真软件中的大地形文件传输技术研究

为了提高仿真速度,仿真软件一般采用多台计算机进行协同工作,首先搭建一套电波传播仿真并行系统,该系统能够导入地理信息,并在导入的地图上进行电磁辐射源建模及电磁环境仿真工作。但是,对于一些很大的地形,其海量的三维地形数据的传输时间过长,这加大了总的仿真等待时间。所以为了综合利用多台计算机的资源优势,提出使用BitTorrent方式,使得服务端与客户端的计算机均可以为地形文件的传输做贡献,极大减少了地形文件传输时间,可以从侧面提高仿真工作的效率。     

Co-metabolic transformation of the neonicotinoid insecticide imidacloprid by the new soil isolate Pseudoxanthomonas indica CGMCC 6648

A new imidacloprid (IMI) degrading bacterium Z-9 (deposited number CGMCC 6648) was isolated and identified as Pseudoxanthomonas indica by 16S rRNA gene analysis. Two metabolites were identified as olefin and 5-hydroxy IMI by liquid chromatography-mass spectrometry and nuclear magnetic resonance analysis. P. indica CGMCC 6648 degraded 70.1% of IMI (1.22 mmol L^?1) and formed 0.93 mmol L^?1 5-hydroxy IMI and 0.05 mmol L^?1 olefin IMI in 6 days and in the presence of 100 mmol L^?1 glucose. The half-life of IMI degradation was 3.6 days. P. indica CGMCC 6648 transforms IMI via a co-metabolism mechanism and different carbohydrates have significant effects on 5-hydroxy IMI formation, whereas different organic acids have substantial effects on olefin IMI production. Lactose is the best co-substrate for IMI degradation and 5-hydroxy IMI formation with 0.77 mmol L^?1 degraded and 0.67 mmol L^?1 formed in 48 h, respectively. Pyruvate is the best co-substrate for olefin IMI formation with 0.17 mmol L^?1 produced in 96 h for all carbon sources tested. Pyruvate significantly stimulates the conversion of 5-hydroxy IMI to olefin IMI, whereas glucose slightly inhibits this reaction. P. indica CGMCC 6648 rapidly degrades IMI and forms olefin IMI, which may enhance its potential for biodegradation of IMI and increase its insecticidal activity, which can decrease the IMI dosage required.     

瑞典环境税——政策效果及其对中国的启示

文章回顾了瑞典的环境税费，特别是与能源相关的环境税的发展沿革，从环境效益、财政效益、能源结构调整效应三个方面分析了瑞典能源一环境税的效果，并展望瑞典环境税的发展前景。最后指出了瑞典环境税制度对中国的借鉴意义。