Influence of the composition and removal characteristics of organic matter on heavy metal distribution in compost leachates

Compost leachates were collected to investigate the influence of the composition and removal of volatile fatty acids (VFAs), humic-like substances (HSs), and dissolved organic nitrogen (DON) on heavy metal distribution during the leachate treatment process. The results showed that acetic and propionic acids accounted for 81.3 to 93.84 % of VFAs, and that these acids were removed by the anaerobic-aerobic process. Humic- and fulvic-like substances were detected by excitation–emission matrix spectroscopy coupled with parallel factor analysis, and their content significantly decreased after the anaerobic and membrane treatments. DON in compost leachates ranged from 26.53 mg L^-1 to 919.46 mg L^-1, comprised of dissolved free amino acids and the protein-like matter bound to humic- and fulvic-like substances, and was removed by the aerobic process. Correlation analysis showed that Mn, Ni, and Pb were bound to VFAs and protein-, fulvic-, and humic-like substances in the leachates. Co was primarily bound to fulvic- and humic-like matter and inorganic sulfurs, whereas Cu, Zn, and Cd interacted with inorganic sulfur.     

Characterizing the heavy metal-complexing potential of fluorescent water-extractable organic matter from composted municipal solid wastes using fluorescence excitation–emission matrix spectra coupled with parallel factor analysis

To investigate the effect of organic matter evolution on heavy metal sorption, fluorescence excitation–emission matrix (EEM) spectra combined with parallel factor (PARAFAC) analysis were employed to characterize the evolution and metal-complexing potential of fluorescent water-extractable organic matter (WEOM) from composted municipal solid wastes (MSWs). The WEOMs examined comprised humic-, fulvic-, tryptophan-, and tyrosine-like substances. Composting treatment increased the content of humic- and fulvic-like matter, and changed the existence pattern of tryptophan- and tyrosine-like substances (i.e., the tryptophan- and tyrosine-like substances from uncomposted MSWs were mainly bound in protein-like matter, whereas those from composted MSWs were primarily bound in humic- and fulvic-like substances). Furthermore, composting treatment increased the polar functional group, aromaticity, and humification degree of the WEOMs, but decreased the aliphatic and hydroxyl group. These evolutions decreased the Cu(II) affinities of fulvic- and humic-like substances and the Pb(II) affinities and complexing capacities of fulvic-like substances, but increased the Cu(II) complexing capacities of fulvic- and humic-like substances. These results reveal that mature composts from the MSWs can be used for the remediation of Cu- and Pb-contaminated soils in situ, whereas immature composts can enhance the metal transferability from soil to plant.     

Shewanellasp．XB缺氧反硝化降解苯酚

苯酚的生物降解一直受到关注。以苯酚为惟一电子供体,研究了Shewanellasp．XB对苯酚的缺氧降解特性。研究结果表明,在反硝化条件下,当C／N为13．3时,苯酚可以完全降解,NO2--N积累量很少。另外,当加入氧化还原介体,如核黄素3μmol／L、AQDS0．01mmol／L、AQS0．05mmol／L和LQ0．01mmol／L时,苯酚降解速率分别为不加介体时的1．45、1．77、1．67和1．63倍。当以氯化铵代替硝酸盐时,苯酚也能进行厌氧发酵降解。另外,菌株XB反硝化降解苯酚可能是厌氧和好氧降解的混合过程。     

改进型生物质阴离子交换纤维制备及吸附性能

用氢氧化钠水溶液预处理,以乙二胺作交联剂,采用环氧氯丙烷和二甲胺对网状植物丝瓜络纤维进行化学改性,制备出改性丝瓜络阴离子交换纤维(LS-AEF),重点探讨了LS-AEF的形态特征并对其形态特征进行了表征分析,还考察了碱预处理对产品吸附水体中的NO-3的影响。研究结果表明,(1)LS-AEF引入带正电的胺基基团,可以提高对NO-3的吸附性能;(2)乙二胺剂量对产品吸附性能影响比较大,最佳剂量为9 mL,吸附率达到75%;(3)碱性预处理能够显著提高产品的吸附性能,碱处理前后的产品吸附率分别为76%和85%;(4)吸附过程符合伪二级动力学方程。     

Shewanella sp.XB缺氧反硝化降解苯酚

苯酚的生物降解一直受到关注。以苯酚为惟一电子供体,研究了Shewanella sp.XB对苯酚的缺氧降解特性。研究结果表明,在反硝化条件下,当C/N为13.3时,苯酚可以完全降解,NO-2-N积累量很少。另外,当加入氧化还原介体,如核黄素3μmol/L、AQDS 0.01 mmol/L、AQS 0.05 mmol/L和LQ 0.01 mmol/L时,苯酚降解速率分别为不加介体时的1.45、1.77、1.67和1.63倍。当以氯化铵代替硝酸盐时,苯酚也能进行厌氧发酵降解。另外,菌株XB反硝化降解苯酚可能是厌氧和好氧降解的混合过程。     

经济发达地区镇域农村居民点演变驱动力空间差异研究

采用Logistic回归分析法、对比分析法等,以地处经济发达地区的陆渡镇及浏河镇为例,从镇域尺度探讨农村居民点演变驱动机理及其空间差异。结果显示：（1）两镇农村居民点减少的一般因素中农民人均纯收入、人均居民点面积均具有正向作用,到城镇的距离具有负向作用,3者作用大小具有区域差异,农村工业发展及到公路的距离对不同地区作用方向不同;而粮食产量仅对陆渡镇有负向作用;（2）两镇农村居民点增加的一般因素中农民人均纯收入、农业发展均具有正向作用,而到公路的距离、基本农田则具有负向作用,4者作用方向及程度排序一致;而除一般因素及到城镇的距离外的其他因素均为特殊因素。研究表明,农村居民点变化驱动力及其作用程度与方向具有区域差异性;为优化农村居民点布局,应把握不同地区农村居民点演变驱动力机理的空间差异,制定差别化政策措施     

基于格网数据的巢湖流域洪涝灾害损失评估

洪涝灾害是区域可持续发展的巨大威胁之一。随着全球气候变化、城市化进程加快和人口与经济集聚,洪涝灾害的损失日益严重。提出了洪涝灾害损失评估流程,建立基于网格数据的洪涝灾害损失估算模型,厘定各类资产的损失率。以空间网格为计算单元,在2003年洪水监测的基础上,应用GIS空间分析技术,对2003年巢湖流域的洪涝灾害损失进行了估算。结果表明：巢湖流域总淹没面积2 12504 km2,水田淹没面积最大,为1 71924 km2,洪涝灾害损失总值为194 828万元,无为、合肥、庐江县等洪涝灾害损失较大,舒城和肥西县损失较小。通过验证,该模型效果较好     

补料频率对牛粪料液酸化效果的影响

研究不同补料频率对牛粪水解酸化特性的影响,以牛粪为发酵原料,在发酵温度为中温(35±1)℃条件下,进行半连续产酸发酵实验,补料频率分别为12、24和36 h/次。结果表明,补料频率影响挥发性脂肪酸(VFA)的积累速度,从快到慢顺序分别为24、36和12 h/次,24 h/次组在第7天挥发酸总量积累最大;在所做实验的补料频率内不影响发酵类型,各组的乙酸与丁酸之和的百分含量均在81%以上,属于丁酸型发酵;p H值6.2左右在丁酸发酵的适宜范围,因此,24 h/次组可以为产甲烷相提供适宜底物。     

改进气相色谱法测定总烃与非甲烷总烃

采用十通阀、双定量环进样(进样量0.5 m L),专用的甲烷柱和总烃柱分别分离两路气样,单FID检测器检测的方法测定环境空气和固定污染源废气中的总烃和非甲烷总烃(NMHC)。实验结果表明:总烃与甲烷工作曲线的相关系数分别为0.997 7和0.999 0;总烃与甲烷测定结果的相对标准偏差均未超过1.5%;总烃与NMHC的检出限均为0.04 mg/m~3;总烃的加标回收率为90.3%~113.0%,NMHC的加标回收率为91.1%~110.0%。上述指标均满足HJ 604—2011和HJ/T 38—1999中对总烃及NMHC的测定要求。用注射器采样后的气样应尽量避光保存,放置时间宜在8 h之内。该方法无需制备除烃空气,大幅提升了检测效率。     

Algae mediate submerged macrophyte response to nutrient and dissolved inorganic carbon loading: A mesocosm study on different species

Nutrient and dissolved inorganic carbon are two important factors that influence the development and species composition of submerged macrophyte communities in shallow lake ecosystems. Yet little is known about their potential interactive effects on the submerged macrophytes and competition outcome of macrophyte–phytoplankton. We performed a mesocosm experiment to investigate the growth and photosynthetic performance of three submerged macrophytes in relation to phytoplankton/epiphyton with nutrient and bicarbonate enrichment. During the experimental period (42 d), increase in nutrient loading in water column resulted in a substantial burst of phytoplankton and epiphyton growth and increased light attenuation. When combined with nutrient loading, bicarbonate enrichment also resulted in a heavily phytoplankton- and epiphyton-dominated state, although bicarbonate enrichment per se does not cause the phytoplankton and epiphyton growth. However, increase in nutrient loading in water column had significant negative impact on individual performances (growth and photosynthesis) of the three submerged macrophytes and bicarbonate enrichment increased the effect of eutrophication on two dissected-leaf macrophytes (M. spicatum and E. nuttallii). Furthermore, our results also suggest that species-specific photosynthetic performances occurred when submerged macrophytes in an environment with high abundance of phytoplankton/epiphyton. This study highlighted that increase in nutrient loading and bicarbonate in water column is likely to interactively impact both abiotic and biotic properties of a freshwater ecosystem. The interactions of these two factors could select macrophyte species that are able to resist the shading from phytoplankton/epiphyton, making these species more dominant in natural freshwater ecosystems.