Source characterisation and mid-term spatial and temporal distribution of polycyclic aromatic hydrocarbons in molluscs along the Basque coast (northern Spain)

The variability of polycyclic aromatic hydrocarbons (PAH) measured in the soft tissues of Mediterranean mussels (Mytilus galloprovincialis) and Pacific oysters (Crassostrea gigas) are investigated. Samples were collected from estuarine waters within the Basque Country (Bay of Biscay), between 2003 and 2011. PAH bioaccumulation showed some seasonality and significant differences were observed between cold (autumn–winter) and warm (spring–summer) seasons. Sites located within the ports of Bilbao and Pasaia showed the highest PAH concentrations in molluscs, and the highest percentages of samples above the established Environmental Quality Standards and Environmental Assessment Criteria. Probably due to human activities carried out in the area, no clear trends were observed, between 2003 and 2011, for the autumn data. Since the Basque coast is an area with high population density and industrial activity, the congener profiles (which reveal the predominance of tetra-aromatics) and the diagnostic ratios identified urban/industrial combustion processes as the main PAH sources. However, natural and petrogenic sources cannot be disregarded.     

Contamination and source assessment of metals,polychlorinated biphenyls,and polycyclic aromatic hydrocarbons in urban soils from Addis Ababa,Ethiopia

Urban areas in developing countries are facing vast environmental problems as a result of rapid urbanization and industrialization. Of major concern is the contamination of soils which are increasingly becoming sinks for environmental pollutants. However, to date only little is known about the pollution in the megalopolises of developing countries. The aim of this study was to assess the contamination and potential sources of metals, polychlorinated biphenyls (PCBs) and polycyclic aromatic hydrocarbons (PAHs) in the urban environment of Addis Ababa, the capital of Ethiopia. The investigation revealed the presence of most of the analyzed pollutants in soil and sediment samples with total concentrations (dry wt) of PAHs ranging from 186 to 3150?µg?kg^?1, PCBs from 0.4 to 19?µg?kg^?1, Cu from 14 to 173?mg?kg^?1, Zn from 36 to 440?mg?kg^?1, Pb from 9 to 700?mg?kg^?1, and Ni from 16 to 72?mg?kg^?1. In addition, polyaromatic sulfur heterocycles, typical for oil and petrol residues, were detected in several soil samples. Source identification approaches revealed that Pb, Zn, and Cu are most likely derived from pyrolytic sources, with elevated values in samples related to waste combustion and traffic emissions. Ni is most probably of geogenic origin. For PCBs it is indicated that they are derived from a single source. However, correlations with technical PCB mixtures were inconsistent. PAHs originate from the combustion of biomass, vehicular exhausts, and petrogenic sources.     

Groundwater quality in the major industrial area of Thessaloniki,Greece part 1: Chemical composition‐geochemical processes

Adsorption rates of Sb(V) ions on an activated alumina (AA) were analyzed by batchwise experiments, while the continuous adsorption, desorption, regeneration of AA, and multiple reuse cycles were studied by flow column tests. The adsorption rates increased quickly with the increases of shaking speed and operation temperature. The adsorbed Sb(V) ions were desorbed easily by a 50 mM NaOH solution, and a 41–90 times concentrated Sb(V) solution was yielded correspondingly. AA was effectively regenerated by desorption operation and ca. 93% of the initial adsorption capacity was retained after six times adsorption/desorption cycles.     

Continuous monitoring of ambient polycyclic aromatic hydrocarbons near open‐air burning of metal scraps

Airborne concentrations of PAH in the vicinity of the source region with open‐air burning of metal scraps were measured between February, 1992 and November, 1993. The activity of open‐air burning decreased significantly since 1993 due to prohibition regulation. Both gaseous phase and particle‐bound PAH were measured at five sampling sites, which included one reference sampling site far away from the source region. Both values of gaseous and particle‐bound PAH concentrations, which were measured in the vicinity of source region, decreased clearly during the two years monitoring period. It shows that the uncontrolled open‐air burning of metal scraps was a significant emission source of airborne PAH in the study area. The profiles of various species of PAH were also compared. A large decrease in benzo(a)pyrene was observed in the source region.     

The Effect of Interaction Between White-rot Fungi and Indigenous Microorganisms on Degradation of Polycyclic Aromatic Hydrocarbons in Soil

White-rot fungi applied for soil bioremediation have to compete with indigenous soil microorganisms. The effect of competition on both indigenous soil microflora and white-rot fungi was evaluated with regard to degradation of polycyclic aromatic hydrocarbons (PAH) with different persistence in soil. Sterile and non-sterile soil was artificially contaminated with ¹⁴C-labeled PAH consisting of three (anthracene), four (pyrene, benz[a]anthracene) and five fused aromatic rings (benzo[a]pyrene, dibenz[a,h]anthracene). The two fungi tested,Dichomitus squalens and Pleurotus ostreatus, produced similar amounts of ligninolytic enzymes in soil, but PAH mineralization by P. ostreatus was significantly higher. Compared to the indigenous soil microflora, P.ostreatus mineralized 5-ring PAH to a larger extent, while the indigenous microflora was superior in mineralizing 3-ring and 4-ring PAH. In coculture the special capabilities of both soil microflora and P. ostreatus were partly restricted due to antagonistic interactions, but essentially preserved. Thus, soil inoculation with P. ostreatus significantly increased the mineralization of high-molecular-weight PAH, and at the same time reduced the mineralization of anthracene and pyrene. Regarding the mineralization of low-molecular-weight PAH, the stimulation of indigenous soil microorganisms by straw amendment was more efficient than application of white-rot fungi.     

Effect of heavy metals and PAH on soil assessed via dehydrogenase assay

Dehydrogenase enzyme activity (DHA) assay method using resazurin was accommodated for measuring of toxicity of compound contaminants on uncharacterized microbial communities present in any given soil. The method was used to compare the toxic effect of heavy metal and polycyclic aromatic hydrocarbon (PAH) contaminant mixture (Cr, Pb, Cu, Cd, Pyrene) on four typical Estonian soils covering a range of compositions. The method proved to be useable on all soils; the sensitivity of soil microbiology to toxic effect of contaminants was found to have a negative correlation with Ca and organic matter (OM) content and a positive correlation with amorphous phase content of soils.     

四川省南充市大气中多环芳烃的分布

用超声波萃取，抽滤，减压蒸发浓缩，硅胶柱净化，再逍缩至干，定客溶解的方法处理了南充市5个监测点冬，夏季乘集的大气颗粒物样品，然后用高效液相色谱法分析其中9种多环芳烃含量，大气中苯并[a]芘的年平均含量为31．5ng/m3，略低于成都市1988年测定的年平均值，南充市大气中多环芳烃的主要来源是居民生活用煤，其次是汽车尾气，改变燃料结构，集中供热，加强城市交通管理，是减少多环芳烃污染的途径。     

太湖流域水源地悬浮颗粒物中的PAH、OCP和PCB

于2010年5月和9月分别对太湖流域水源地悬浮颗粒物(SPM)中的PAH、OCP和PCB的残留水平进行了检测和分析.结果表明,研究区PAH、OCP和PCB的含量分别为806.9~3815.3ng/g、10.04~50.86ng/g和2.20~5.06ng/g.与5月份相比,9月份的大部分采样点三种污染物含量有所增加.PAH中HMW-PAHs的含量占优势,主要来源于石油类排放、石油及其精炼产品的不完全燃烧,少量来源于煤和生物质的不完全燃烧.OCP中DDTs的含量占优势,研究区有新的HCHs和林丹输入,但DDTs没有新的输入.Aroclor检出率最高的为Aroclor1016与Aroclor1260,这可能与我国主要生产和使用的PCBs产品有关.相对于国内外其他地区监测结果和评价标准,研究区SPM所受PAH、OCP和PCB污染较轻,大部分地区均低于生态影响低值LEL,生态风险较小.     

污染源减排时刻和减排比例对北京市PM_(2.5)浓度的影响

利用Model-3/CMAQ及京津冀地区高分辨率排放源清单,选取文献[19]中污染峰值当天启动50%污染源削减方案的同时,进一步设置了3种污染源控制方案(峰值当天启动75%源削减;峰值日前1d、2d开始启动25%源削减),比较了峰值日前启动适量减排与峰值日当天启动大幅度减排的效果差异.结果表明:污染峰值当天启动50%、75%减排时,北京市PM2.5浓度下降率分布不均匀,高值区集中于PM2.5浓度高值区,减排后PM2.5浓度分布较减排前均匀.提前1~2d启动25%源削减时,峰值日北京市PM2.5浓度整体下降.城、郊PM2.5下降率均表现为当天减排50%小于提前1d开始减排25%;当天启动减排提高到75%时,城区PM2.5下降率大于提前2d启动25%减排,郊区表现为峰值前2d启动25%削减优于当天减排75%.将峰值前1d、2d启动25%减排分别与当天启动50%、75%减排时北京市峰值日PM2.5浓度下降率相减,北京市绝大部分区域下降率差值为正;峰值前1d、2d启动25%减排分别比峰值日启动50%、75%减排时北京市平均PM2.5多下降4.7μg/m3(6%)、2.9μg/m3(4%).综上所述,在污染峰值来临之前采取适量减排较污染当天才启动大幅度减排更有利于北京市整体空气质量达标.     

The performance of a combined nitritation-anammox reactor treating anaerobic digestion supernatant under various C/N ratios

A combined nitritation–anammox reactor was developed to treat the digestion supernatant under various C/N ratios. Due to the difficulties for heterotroph to utilize the refractory organics, the reactor presented relatively stable performance with increasing supernatant addition. Nevertheless, the adverse effects of supernatant would accumulate during the long-term operation and thus weakened the activity and shock resistance of microbes,which further led to the gradual decrease of reactor performance after 92 days' operation.Under this circumstance, supernatant with volatile fatty acids(VFAs) residuals was further introduced into the reactor to investigate the performance of combined nitritation–anammox process with VFA addition. With the appearance of VFAs, the nitrogen removal performance gradually restored and the reactor finally achieved stable and efficient performance with C/N ratio of 0.35. The VFA residuals within 150 mg/L in the supernatant served as the extra electron donors and stimulated the heterotrophic denitrification process, which was vital for the enhancement of reactor. The nitrogen removal rate and total nitrogen removal efficiency reached 0.49 kg N/(m3·day) and 88.8% after 140 days' operation, respectively. The combined nitritation–anammox reactor was proved suitable to treat digestion supernatant.