底泥原位洗脱过程中氮磷含量与形态变化特征

随着城市化进程的不断推进,城市河流底泥中内源氮磷污染问题日益突出.为研究原位洗脱技术对污染底泥中氮、磷物质和成分的作用效果,以北京市凉水河作为研究对象,分别比较了现场试验洗脱与对照组0~30 cm分层底泥以及实验室模拟洗脱处理前后0~10 cm底泥中pH、E_h（氧化还原电位）、容重、含水率、OM（有机质）、TN、TP和氮、磷形态分布的变化特征.结果表明:①现场洗脱对0~5 cm厚度底泥的处理和模拟洗脱处理均对底泥中pH、E_h、含水率的改变以及其中TN、TP的去除效果表现显著,其中,现场试验洗脱组0~5 cm范围底泥中w（TN）、w（TP）分别较对照组降低了66.4%±17.4%、40.8%±24.4%,模拟洗脱处理对底泥中OM、TN、TP的去除率分别达70.1%±4.8%、66.8%±2.0%、43.1%±3.1%.②原位洗脱技术对底泥中TN的去除主要通过对PON（颗粒态有机氮）的去除来实现,现场和模拟试验过程中PON对TN去除的贡献率分别达55.0%和73.6%.③原位洗脱对底泥中TP的去除主要通过对Al-P（铝结合态磷）、OP（有机磷）的去除来实现,现场和模拟试验中Al-P、OP对TP去除的贡献率分别达37.0%、66.2%和31.3%、43.7%.研究显示,原位洗脱技术可有效去除城市河流底泥处理层中的氮磷物质,并以有机氮、磷物质的去除为主.      

原位洗脱技术对凉水河底泥中氮、磷释放特征的影响

为探讨新兴底泥原位修复技术—原位洗脱技术对城市河流凉水河底泥中氮、磷释放的抑制作用,于现场采集洗脱前后样品并设计室内静态模拟实验,分析了实验期间洗脱组和对照组上覆水中NH_4~+-N、NO_3~--N、TN、PO_4~(3-)-P、TP浓度和释放速率变化特征。结果表明:洗脱组释放第30天时,NH_4~+-N由底泥向上覆水中平均NH_4~+-N平均浓度为0.52 mg·L~(-1),较对照组下降了89.4%;PO_4~(3-)-P和TP平均释放速率较对照组降低了78.1%和83.0%,上覆水中TP平均浓度为0.22 mg·L~(-1),较对照组下降了68.1%。原位洗脱技术对底泥中NH_4~+-N、PO_4~(3-)-P释放的抑制作用主要通过对有机氮、磷物质的削减和水-沉积物界面还原环境的改善来实现。     

A new fossil thryonomyid from the Late Miocene of the United Arab Emirates and the origin of African cane rats

Cane rats (Thryonomyidae) are represented today by two species inhabiting sub-Saharan Africa. Their fossil record is predominately African, but includes several Miocene species from Arabia and continental Asia that represent dispersal events from Africa. For example, Paraulacodus indicus, known from the Miocene of Pakistan, is closely related to living Thryonomys. Here we describe a new thryonomyid, Protohummus dango, gen. et sp. nov., from the late Miocene Baynunah Formation of the United Arab Emirates. The new thryonomyid is less derived than “Thryonomys” asakomae from the latest Miocene of Ethiopia and clarifies the origin of crown Thryonomys and the evolutionary transition from Paraulacodus. A phylogenetic analysis shows Protohummus dango to be morphologically intermediate between Paraulacodus spp. and extinct and living Thryonomys spp. The morphological grade and phylogenetic position of Protohummus dango further supports previous biochronological estimates of the age of the Baynunah Formation (ca. 6–8 Ma).     

Elemental composition of sediments in Lake Jinzai, Japan: Assessment of sources and pollution

Bottom sediments from Lake Jinzai in southwest Japan were analyzed to determine their chemical compositions and to assess the potential for ecological harm by comparison with sediment quality guidelines. The pollution status of lake sediments was evaluated by employing contamination factor (CF), pollution load index (PLI), and geoaccumulation index (I(geo)), focusing on a suite of elements in lakebed and core sediments. Elevated concentrations of As, Pb, Zn, Cu, TOC, N, and P were present in several layers of the upper core and other surface sediments. The elevated metal concentrations are likely related to the fine-grained nature of the sediments, reducing bottom conditions produced by abundant organic matter, and possibly minor non-point anthropogenic sources. Moreover, correlations between the concentrations of trace metals and organic carbon, nitrogen, phosphorus, and iron, suggest that these elements play a role in controlling abundances. Calculated CF, PLI, and I(geo) indicate that the sediments are strongly polluted with respect to As, moderately to strongly polluted with Zn, and moderately polluted with Pb and Cu. Metal concentrations exceed the New York State Department of Environmental Conservation (NYSDEC) lowest effect level and the Canadian Council of Ministers of the Environment (CCME) interim sediment quality guidelines that indicate moderate impact on aquatic organisms in the study area.     

Development and validation of LC-MS/MS method for the determination of Ochratoxin A and its metabolite Ochratoxin α in poultry tissues and eggs

The objective of this study was to develop a liquid chromatography tandem mass spectrometry (LC-MS/MS) method for the determination of Ochratoxin A (OTA) and Ochratoxin α (OTα) in poultry tissues and eggs. The two toxins were extracted by a mixture of acetonitrile/water, purified with a reversed phase C18 solid phase extraction column (SPE) and determined by LC-MS/MS. The LC-MS/MS method performances were evaluated in terms of linearity in solvent and in matrix (ranged from 0.5 to 15.10 µg L^?1 for OTA and from 0.60 to 17.85 µg L^?1 for OTα), limit of detection (LOD), limit of quantitation (LOQ), specificity, accuracy and precision in repeatability conditions. Recovery experiments were performed by spiking poultry liver, kidney, muscle and eggs around 1 µg kg^?1 and 10 µg kg^?1. LODs were 0.27 and 0.26 µg kg^?1 while LOQs were fixed at 1.0 and 1.2 µg kg^?1 for OTA and OTα, respectively. Main recoveries for OTA ranged from 82 to 109% and for OTα ranged from 55 to 89%. The values of within-laboratory relative standard deviation (RSD_r) were equal to or below 20%. Considering the results obtained and that all analytical performance criteria were fulfilled, the new extraction and purification method developed for OTA and OTα determination in animal tissues and eggs was found appropriate for control laboratories and research activities designed to ensure food safety.     

超声波对滇池蓝藻伪空胞和群体沉降性能的影响

为提高混凝沉淀藻水分离技术的分离效果,以滇池新鲜蓝藻为研究对象,研究不同超声波处理条件下,超声波对伪空胞、蓝藻群体沉降性能及水体水质的影响。结果表明:超声波对伪空胞的破坏效果满足准一级动力学规律,反应速率常数k随着超声波功率密度的增大而增大,并逐步趋于饱和;短时间低功率(5 s,5.0～16.7 W·L~(-1))的超声波能破坏伪空胞,改善蓝藻群体沉降性能,降低水体pH,且对水体DTN、DTP浓度的影响5%;在保证出水安全的前提下,综合考虑处理效果和经济成本,超声波功率密度16.7 W·L~(-1)、处理时间5 s为超声波处理滇池藻样的最佳条件,该条件下蓝藻伪空胞破坏率、沉降率分别为84%、80%。利用超声波对滇池蓝藻进行处理,确定了超声波对滇池蓝藻的伪空胞有破坏作用,可以改善蓝藻群体的沉降性能,达到大规模、无污染的藻水分离的目的,为蓝藻水华控制提供参考。     

Microbial contamination of drinking water in Pakistan—a review

Water pollution with pathogenic microorganisms is one of the serious threats to human health, particularly in developing countries. The main objective of this article is to highlight microbial contamination of drinking water, the major factors responsible for microbial contamination, and the resulting health problems in Pakistan. Furthermore, this study will be helpful for researchers and administrative agencies to initiate relevant studies and develop new policies to protect further deterioration of water supply with pathogenic microbes and ensure clean and safe drinking water to the public in Pakistan. In Pakistan, water at the source, in the distribution network, and at the consumer tap is heavily polluted with coliforms and fecal coliforms all over the country. An overview of more than 7,000 water samples reviewed here reveals that an average of over 71 and 58 % samples in the country was contaminated with total coliforms and fecal coliforms, respectively. Drinking water contamination accounts for 20 to 40 % of all diseases in the country, which causes national income losses of Rs 25–58 billion annually (US$0.25–0.58 billion, approximately 0.6–1.44 % of the country’s GDP). Improper disposal of industrial and municipal wastes is the most important factor responsible for water pollution in the country followed by cross-contamination due to old and leaking pipes and lack of water filtration and disinfection facilities. There is an urgent need for emergency steps to stop further deterioration of water quality and improve the existing water quality so as to protect the public from widespread waterborne diseases.     

Testing environment Kuznets curve (EKC) hypothesis in different regions

Environmental Science and Pollution Research - This study examines the association between air pollution and economic growth based on the idea of environment Kuznets curve (EKC) hypothesis which...     

调蓄经济植物湿地技术在农田径流污染控制中的工程应用及评价

为评价调蓄经济植物湿地技术在农田径流污染控制中的运行效果和经济效益,采用现场调研长期跟踪监测调蓄经济植物湿地进、出水水质和水量变化,深入探索其营养盐质量浓度分布特征及其去除效能.结果表明:①调蓄经济植物湿地能够有效截留营养盐,稳定出水水质,2015年7月-2017年4月出水ρ（TN）、ρ（TP）和ρ（COD_Cr）平均值分别为1.2、0.07和17.0 mg/L,TN、TP和COD_Cr去除率分别为65.8%、75.5%和41.3%.②不同调蓄量下TN和TP去除率随着进水水量的增大而减小,表现为枯水期>平水期>丰水期;COD_Cr去除率与调蓄量之间呈负相关,表现为丰水期>平水期>枯水期;在调蓄经济植物湿地中单位面积TN、TP和COD_Cr去除负荷量表现为丰水期>平水期>枯水期.③调蓄经济植物湿地中莲藕、海菜花和螺蛳产量分别为26.25、22.50和2.46 t/（hm2·a）,氮、磷去除总量分别为275和30 kg/（hm2·a）.研究显示,调蓄经济植物湿地能够有效截留氮、磷,在不同水文期均有良好的净化效果,不仅具备景观效益,且具有良好的经济价值.      

The impact of COVID-19 pandemic on air pollution: a global research framework,challenges, and future perspectives

Environmental Science and Pollution Research - As a result of extreme modifications in human activity during the COVID-19 pandemic, the status of air quality has recently been improved. This...