METHANE POTENTIAL OF FOOD WASTE AND ANAEROBIC TOXICITY OF LEACHATE PRODUCED DURING FOOD WASTE DECOMPOSITION

The objective of this study was to characterize the anaerobic biodegradation of food waste, including its methane potential and the anaerobic toxicity of leachate associated with food waste decomposition. Biodegradation experiments were conducted in 2.2-litre reactors and were seeded with well-decomposed refuse. Despite pH neutralization, reactors seeded with 30% old refuse failed to undergo methanogenesis. Food waste in a second set of reactors, containing 70% seed, produced 300.7 ml CH₄dry g⁻¹. Leachate toxicity was evaluated by a modified anaerobic toxicity assay (ATA). The results of ATAs were typically consistent with the methane production behavior of the reactors. However, the toxicity observed in the ATA test could not be simulated with synthetic leachate containing high concentrations of carboxylic acids and sodium. Tests with 20, 5, 15 and 12 g l⁻¹of acetate, propionate, butyrate and sodium, respectively, suggested that high concentrations of butyric acid and sodium inhibited the onset of methane production but that refuse micro-organisms could acclimatize to these concentrations within 5–10 days. The refuse ecosystem was shown to tolerate higher concentrations of undissociated carboxylic acids than previously reported for anaerobic digesters.     

Effect of atmospheric precipitation on the dissolved loads of the Dongjiang River, China

IntroductionTheatmosphericprecipitationhaslongbeenrecognizedasprovidinganinputofsubstancetothesurfacewaterandasourceofelementscarriedbyrivers (Stallard ,1981;Meybeck ,1983) .Itisestimatedthatapproximately 3 0 %ofsoluteloadsofworldriversarederivedfromthera…     

桑沟湾溶解态汞的生物地球化学行为

作为一种毒性极强的重金属元素,汞在海洋中可以通过海洋生物的呼吸、摄食和吸附等过程被利用,并在沿食物链传递的过程中不断富集,最终危害人类的健康。利用冷原子荧光光度法(CV-AFS)对2011年4月、8月、10月和2012年1月桑沟湾溶解态无机汞(DIHg)和溶解态有机汞(DOHg)的含量进行了测定。结果表明,桑沟湾四个季节DIHg的浓度范围分别为52~865、131~359、31~134和22~119 pmol·L-1,DOHg的浓度范围分别为37~214、52~635、21~98和未检出~51 pmol·L-1。桑沟湾DIHg和DOHg具有相似的分布特征,均呈现出从近岸向外海逐渐降低的趋势,有明显的季节变化。桑沟湾DIHg和DOHg的周日变化与潮汐呈现出较好的负相关关系,且存在明显的昼夜差异。影响桑沟湾DIHg和DOHg分布的主要因素包括河流和地下水的输入、大气的干湿沉降、与黄海的交换、活性气态汞(Hg0)在海-气界面的交换、表层水体发生的光化学还原反应以及养殖生物的清除等。通过初步计算,桑沟湾溶解态汞(TDHg)的存留时间约为(1.27±0.53)年,远远低于大洋。根据美国国家环境保护局汞的质量标准和我国地表水环境质量标准,桑沟湾没有明显的汞污染。但海产品体内富集的汞可能会带来潜在的生态危机和食品安全问题,需要相关部门加以重视,确保桑沟湾养殖产业的平衡发展。     

城市大气颗粒物表面半醌自由基的测定方法

采集上海市城区和郊区2个典型站位的大气颗粒物样品,以二氯甲烷作萃取溶剂,采用索氏抽提法萃取分离吸附在颗粒物表面的稳定自由基,并利用电子自旋共振波谱技术(ESR)分析测定其种类和浓度。结果表明,测试样品的波谱特征表现为显著的三重信号峰,且g因子值均为2.002 7~2.004 7,通过与醌类物质的碱性饱和溶液ESR图谱比对,可以推断颗粒物表面至少吸附一种邻位半醌自由基。同时,通过锰标定量的方式估算了闵行和普陀2个采样点颗粒物样品表面的半醌自由基浓度,闵行采样点TSP、PM10和PM2.5表面半醌自由基的平均浓度分别为5.02×105、5.54×105、9.43×105g-1,而普陀采样点的平均浓度分别为2.02×105、3.50×105、7.16×105g-1。     

Identification of groundwater microbial communities and their connection to the hydrochemical environment in southern Laizhou Bay,China

Environmental Science and Pollution Research - The microbial community plays an important role in the biogeochemical cycle in coastal groundwater ecosystems. However, the composition and...     

加速溶剂萃取-气相色谱-质谱法同时测定土壤中7种Aroclor系列多氯联苯

采用加速溶剂萃取,Florisil固相萃取小柱净化,GC-MS法同时测定土壤中7种多氯联苯(Aroclor 1016、1221、1232、1242、1248、1254、1260)的含量。建立了一种全新的Aroclor系列多氯联苯的定量测定方法,根据氯代联苯峰在单种Aroclor和7种Aroclor混合物中峰高比值(K)固定不变的原理,通过7种Aroclor混合物的标准曲线,计算得出各种Aroclor的标准曲线,测定样品中Aroclor的含量;采用建立多元一次方程组的方法,测定样品中多种不同浓度Aroclor的含量,大大提高了分析效率。7种Aroclor混合物和Aroclor1242、Aroclor1260的土壤加标样品回收率为90.5%~109%,RSD为0.96%~9.38%(n=5),均能满足分析准确度和精密度的要求。     

加速溶剂萃取-气相色谱-负化学离子化质谱法测定土壤中有机磷农药

用加速溶剂萃取法(ASE)萃取土壤中的有机磷农药,用气相色谱-负化学离子化质谱法(GC-NCI-MS)进行测定,并与气相色谱-电子轰击电离质谱法(GC-EI-MS)进行了对比。结果表明,EI法和NCI法均能满足目前的有机磷农药的分析需要。GC-EI-MS的适用范围比较广,操作比较简单;GC-NCI-MS在选择性和灵敏度等方面均具有较强优势。