The role of primary and secondary air pollutants in atmospheric pollution: Athens urban area as a case study

The question to what extent primary and secondary air pollutants are relevant to atmospheric pollution and their effects on human health and the quality of the environment can be answered in a straight-forward manner: atmospheric processes, including oxidation procedures, particle formation and equilibria, determine the fate of primary emissions and, in most cases, the secondary products of these processes are the more important ones concerning their effects on human health and the quality of the environment. The formation of secondary products represents the critical property determining the establishment of certain air standards, rather than the actually emitted substance, although there are notable exceptions. In this paper, a review concerning transformation of primary pollutants as studied in the atmosphere of Athens is used to enlighten matters that may need further attention by the responsible authorities and stakeholders for the control and reduction of atmospheric pollution.     

Emission factors and chemical characterisation of fine particulate emissions from modern and old residential biomass heating systems determined for typical load cycles

It is already well known that there are significant differences regarding the emissions, especially particulate matter (PM) emissions, of old and modern as well as automatically and not automatically controlled biomass based residential heating systems. This concerns their magnitude as well as their chemical composition. In order to investigate emission factors for particulate emissions and the chemical compositions of the PM emissions over typical whole day operation cycles, a project on the determination and characterisation of PM emissions from the most relevant small-scale biomass combustion systems was performed at the BIOENERGY 2020+ GmbH, Graz, Austria, in cooperation with the Institute for Process and Particle Engineering, Graz University of Technology. The project was based on test stand measurements, during which relevant operation parameters (gaseous emissions, boiler load, flue gas temperature, combustion chamber temperature etc.) as well as PM emissions have been measured and PM samples have been taken and forwarded to chemical analyses. Firstly, typical whole day operation cycles for residential biomass combustion systems were specified for the test runs. Thereby automatically fed and automatically controlled boilers, manually fed and automatically controlled boilers as well as manually fed stoves were distinguished. The results show a clear correlation between the gaseous emissions (CO and OGC) and the PM₁ emissions. It is indicated that modern biomass combustion systems emit significantly less gaseous and PM emissions than older technologies (up to a factor of 100). Moreover, automatically fed systems emit much less gaseous and PM emissions than manually fed batch-combustion systems. PM emissions from modern and automatically controlled systems mainly consist of alkaline metal salts, while organic aerosols and soot dominate the composition of aerosols from old and not automatically controlled systems. As an important result comprehensive data concerning gaseous and PM emissions of different old and modern biomass combustion systems over whole day operation cycles are now available. Derived from these data, correlations between burnout quality, particulate emissions as well as particle composition of the PM emissions can be deduced.     

Distribution,seasonal variation and inhalation risks of polychlorinated dibenzo-<Emphasis Type="Italic">p</Emphasis>-dioxins and dibenzofurans,polychlorinated biphenyls and polybrominated diphenyl ethers in the atmosphere of Beijing,China

Spatial distribution, seasonal variation and potential inhalation risks of polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs), polychlorinated biphenyls (PCBs) and polybrominated diphenyl ethers (PBDEs) were investigated in the atmosphere of Beijing, using passive air samplers equipped with polyurethane foam disks. Concentrations of ΣPCDD/Fs, ΣPCBs and ΣPBDEs ranged from 8.4 to 179 fg WHO₂₀₀₅-TEQ/m³, 38.6–139 and 1.5–176 pg/m³, respectively. PCDFs showed higher air concentrations than those of PCDDs, indicating the influence of industrial activities and other combustion processes. The non-Aroclor congener, PCB-11, was detected in air (12.3–99.4 pg/m³) and dominated the PCB congener profiles (61.7–71.5% to ∑PCBs). The congener patterns of PBDEs showed signatures from both penta-BDE and octa-BDE products. Levels of PCDD/Fs, PCBs and PBDEs at the industrial and residential sites were higher than those at rural site, indicating human activities in urban area as potential sources. Higher air concentrations of PCDD/Fs, PCBs and PBDEs were observed in summer, which could be associated with atmospheric deposition process, re-volatilization from soil surface and volatilization from use of technical products, respectively. Results of inhalation exposure and cancer risk showed that atmospheric PCDD/Fs, dioxin-like PCBs and PBDEs did not cause high risks to the local residents of Beijing. This study provides further aid in evaluating emission sources, influencing factors and potential inhalation risks of the persistent organic pollutants to human health in mega-cities of China.     

喜马拉雅山区葇籽草和棘豆样品中PCBs、PBDEs和PCDD/Fs的分析

应用同位素稀释-高分辨气相色谱/高分辨质谱(HRGC/HRMS)法分析了喜马拉雅山区海拔5000 m以上的葇籽草和棘豆样品中多氯联苯(PCBs)、多溴联苯醚(PBDEs)和二噁英(PCDD/Fs)的含量.这两种植物样品中污染物含量与世界其它偏远地区的水平基本保持一致.其中PCBs的总含量在1.94—3.62 ng.g-1干重(dw)范围内,平均值为2.60 ng.g-1dw;PCB-28和PCB-52的浓度明显较高,约占7种指示性PCBs总量的90%以上.14种PBDEs的总浓度在83.3—142 pg.g-1dw之间,平均值为116 pg.g-1dw;除BDE-85、-138、-154,以及高溴代的BDE-190和BDE-209未检出外,其它9种单体均有不同程度的检出,且以低溴代的BDE-28为主,含量占45%以上.样品中PCDD/Fs基本上未检出.由于样品采集点位于喜马拉雅山人迹罕至的珠穆朗玛峰北坡地区,周围并无工业污染源,因此植物样品中PCBs及PBDEs可能是污染物发生大气长距离传输和生物富集的结果.     

Treibhausgas-Emissionen zukünftiger Erdgas-Bereitstellung für Deutschland

Background

Natural gas makes a significant contribution to the current energy supply and its importance, in relation to both the German and worldwide energy supplies, will increase further in decades to come. In addition to its high degree of efficiency, the low level of direct GHG combustion emissions is also an advantageous factor. However, around 90% of natural gas is methane (CH₄), which is the second most significant GHG due to its high greenhouse potential (21 times higher than CO₂). Therefore, high levels of direct gas losses of natural gas in its production, processing, transport and distribution could neutralise its low emission advantages. This is particularly apparent when considering the growing distances between production and use, the demanding production processes and the upcoming worldwide market for LNG (liquefied natural gas).

Aim

This paper aims to analyse and illustrate the future GHG emissions of the whole process chain of natural gas (indirect emissions) to be supplied to the German border over the next 2 decades. This should allow the comparison of total GHG emissions (indirect and direct) of natural gas with the GHG emissions of other fossil fuels. By considering likely changes in gas origin as well as dynamic changes in the infrastructure and technology of gas production, processing and transport until 2030, all relevant factors are included. The study focuses on the emissions of Russian natural gas as Russia is already, and will be in the future, the most important gas supplier to the German and European gas markets.

Results and Discussion

The analysis illustrates a significant change in the gas supply over the next two decades. The EU Gas Fields are in decline and it is predicted that these will run dry. In parallel the share of Russian and Norwegian natural gas, and also the levels of LNG production (e.g. from Algeria or Egypt), will increase. Although the potential for GHG emissions tends to grow as a result of greater transport distances and demanding production and processing activities, high investment in necessary mitigation options (e.g. through replacing older and inefficient technology; updating to state-of-the-art technology) may neutralise the increase. The overall result of these counteracting trends will be to decrease GHG emissions, in a range of around 12% per TJ of direct emissions of natural gas, depending on the level of investment in the modernisation of the Russian gas infrastructure and the improvements of the LNG process. In the two given scenarios the indirect emissions of the natural gas used in Germany will decrease from about 23 million t CO₂-eq (2005) to 19.5 or 17.6 million t CO₂-eq in the year 2030. In spite of a significant higher gas consumption the emissions are reduced in the first scenario due to technical modifications. In the second scenario the emission reduction is based on the lower gas consumption.

Conclusions

At present, the indirect GHG emissions of the natural gas process chain are comparable to the indirect emissions produced by oil and coal. The emission trend of the natural gas process chain will markedly decrease if the mitigation options are followed consistently. However, in order to ensure the long-term security of natural gas supply for future decades, a high level of investment is essential. With regard to future emissions, the best available technology and, therefore, that which is most economically feasible in the long term, should be used. Under these conditions natural gas — as the fossil fuel with the lowest levels of GHG emissions — can play a major role in the transition to a renewable energy supply for the future.     

Co-pyrolysis of sewage sludge and biomass for stabilizing heavy metals and reducing biochar toxicity: A review

The huge amounts of sewage sludge produced by municipal wastewater treatment plants induce major environmental and economical issues, calling for advanced disposal methods. Traditional methods for sewage sludge disposal increase greenhouse gas emissions and pollution. Moreover, biochar created from sewage sludge often cannot be used directly in soil applications due to elevated levels of heavy metals and other toxic compounds, which alter soil biota and earthworms. This has limited the application of sewage sludge-derived biochar as a fertilizer. Here, we review biomass and sewage sludge co-pyrolysis with a focus on the stabilization of heavy metals and toxicity reduction of the sludge-derived biochar. We observed that co-pyrolyzing sewage sludge with biomass materials reduced heavy metal concentrations and decreased the environmental risk of sludge-derived biochar by up to 93%. Biochar produced from sewage sludge and biomass co-pyrolysis could enhance the reproduction stimulation of soil biota by 20‒98%. Heavy metals immobilization and transformation are controlled by the co-feed material mixing ratio, pyrolysis temperature, and pyrolysis atmosphere.

     

奶牛粪便翻堆式与槽式堆肥过程气体排放规律及养分损失原位监测

为探究奶牛粪便翻堆式与槽式堆肥过程中温室气体和氨气(NH₃)排放规律及养分损失情况,采用原位监测的方法,通过静态采气箱和气体在线监测设备,分别对奶牛粪便翻堆式和槽式堆体开展为期36 d的气体监测。结果表明,翻堆式堆肥过程中甲烷(CH₄)、氧化亚氮(N2_O)和NH₃排放主要集中于翻堆阶段;槽式堆肥过程中CH₄和NH₃排放主要集中于堆肥前期,N2_O排放则主要集中于堆肥中后期。堆体管理措施及物料特性显著影响堆肥气体的排放。翻堆式堆肥过程中翻堆对气体排放的影响大于堆肥理化因子如温度、含水率以及pH值;而槽式堆肥过程中,降低堆体的平均温度可同时减缓堆肥过程中CH₄、二氧化碳(CO₂)和NH₃的释放。从养分损失来看,翻堆式和槽式堆肥过程中碳素总损失量分别占堆肥物料初始总碳含量(TC)的27.16%和21.53%,其中约80%以上的碳素损失来自CO₂-C。而堆肥过程中氮素总损失量分别占堆肥物料初始总氮含量(TN)的18.67%和13.44%,其中约80%以上的氮素损失来源于NH₃N。该研究表明,在保证堆体物料腐熟的前提下,降低翻堆频率可显著减缓翻堆式堆肥过程中温室气体和NH₃的排放;降低槽式堆肥堆体的温度可显著减少堆肥过程中CH₄、CO₂和NH₃的排放。该研究结果对于减少堆肥过程气态污染物排放和养分损失,提高堆肥效率具有重要的指导意义。     

Integrierte Treibhausgasbewertung der Prozessketten von Erdgas und industriellem Biomethan in Deutschland

Background The use of natural gas has increased in the last years. In the future, its import supply and transport structure will diversify (longer distances, higher share of LNG (liquefied natural gas), new pipelines). Thus the process chain and GHG emissions of the production, processing, transport and distribution might change. Simultaneously, the injection of bio methane into the natural gas grid is becoming more important. Although its combustion is regarded as climate neutral, during the production processes of bio methane GHG emissions are caused. The GHG emissions occurring during the process chain of energy fuels are relevant for the discussion on climate policy and decision making processes. They are becoming even more important, considering the new Fuel Quality Directive of the EU (Dec. 2008), which aims at controlling emissions of the fuel process chains. Aim In the context of the aspects outlined above the aim is to determine the future development of gas supply for Germany and the resulting changes in GHG emissions of the whole process chain of natural gas and bio methane. With the help of two gas consumption scenarios and an LCA of bio methane, the amount of future emissions and emission paths until 2030 can be assessed and used to guide decision processes in energy policy. Results and discussion The process chain of bio methane and its future technical development are outlined and the related emissions calculated. The analysis is based on an accompanying research study on the injection of bio methane to the German gas grid. Two types of biogas plants have been considered whereof the “optimised technology” is assumed to dominate the future market. This is the one which widely exploits the potential of process optimisation of the current “state of the art” plant. The specific GHG emissions of the process chain can thus be nearly halved from currently 27.8?t CO₂-eq./TJ to 14.8?t CO₂-eq./TJ in 2030. GHG emissions of the natural gas process chain have been analysed in detail in a previous article. Significant modifications and a decrease of specific emissions is possible, depending on the level of investment in the modernisation of the gas infrastructure and the process improvements. These mitigation options might neutralise the emission increase resulting from longer distances and energy intensive processes. In the last section two scenarios (low and high consumption) illustrate the possible development of the German gas supply until 2030, given an overall share of 8–12?% of bio methane. Considering the dynamic emission factors calculated in the former sections, the overall gas emissions and average specific emissions of German gas supply can be given. The current emissions of 215.4 million t CO₂-eq. are reduced by 25?% in the low-consumption scenario (162 million t CO₂-eq.), where consumption is reduced by 17?%. Assuming a consumption which is increased by 17?% in 2030, emissions are around 7?% higher (230.9 million t CO₂-eq.) than today. Conclusions Gaseous fuels will still play a significant role for the German energy supply in the next two decades. The GHG emissions mainly depend on the amount of gas used. Thus, energy efficiency will be a key issue in the climate and energy related policy discussion. A higher share of bio methane and high investments in mitigation and best available technologies can significantly reduce the emissions of the process chain. The combustion of bio methane is climate neutral compared to 56?t CO₂/TJ caused by the direct combustion of natural gas (or 111?t CO₂/TJ emitted by lignite). The advantage of gaseous energy carriers with the lowest levels of GHG emissions compared to other fossil fuels still remains. This holds true for fossil natural gas alone as well as for the expected future blend with bio-methane.     

多氯联苯污染土壤热脱附研究综述

综述了近年来国内外热脱附技术在修复多氯联苯(polychlorinated biphenyls,PCBs)污染土壤方面的研究进展。温度和停留时间是影响其脱附效率的最主要因素,另外脱附效果还受土壤性质以及载气、压力等其他因素的影响。氧气存在的条件下,脱附过程中会有呋喃(polychlorinated dibenzofurans,PCDFs)生成,导致整体毒性当量增加。PCBs的物理蒸发是其主要的脱附机制,同时伴随着脱氯和降解。协同热脱附通过添加改性剂,有效促进了PCBs的去除以及降解。冷凝,除尘,吸附一系列尾气处理用来降低尾气中PCBs的含量。文章最后给出了当前国内外的应用情况以及存在问题和今后的发展方向。     

重点源大气砷铅污染排放模型及特征

在我国的非常规性污染物质中,大气重金属砷、铅已越来越多地被关注和重视。文章综述了国内外人为源对大气中重金属排放的贡献,结果显示中国是全球人为活动向大气排放重金属最多的国家之一,燃煤和有色金属冶炼行业在相当长的时间内都将是最主要且最为重要的人为排放源。通过系统调研燃煤及有色金属冶炼业资源及产业布局状况,构建目前我国大气重金属相关清单模型,进行了我国重点源大气砷、铅排放清单分析,结果表明：（1）2000-2008年我国燃煤大气砷、铅排放量共为93733t,年均增长率为7．93％,2004-2008年有色金属冶炼业大气砷、铅排放量共为18836t,年均增长率为15．2％;（2）2000-2008年各经济部门中电力部门燃煤大气砷、铅放量始终最高,占燃煤大气排放总量的44．6％-57．1％,且呈逐年升高的趋势;（3）2000-2008年各省区中山西、河北、河南和湖南省是大气砷、铅的排放大户。其中,燃煤大气砷、铅排放量主要集中在人口密集、工业集中、经济发展速度较快的北部和中东部省区,包括山西、山东、河北、河南和江苏五省,占全国燃煤排放总量的39．1％,有色金属冶炼大气砷、铅排放量主要集中在我国有色金属工业较为发达的河南及湖南省,占全国有色金属冶炼业排放总量的47．3％。可以看出,我国需要高度重视大气重金属砷、铅的污染防治,加强排放控制基础能力建设,加快建立适合中国的大气砷、铅污染防治技术政策体系。     

Aquatic metabolism and ecosystem health assessment using dissolved O2 stable isotope diel curves.

Dissolved O2 concentration and delta18O-O2 diel curves can be combined to assess aquatic photosynthesis, respiration, and metabolic balance, and to disentangle some of the confounding factors associated with interpretation of traditional O2 concentration curves. A dynamic model is used to illustrate how six key environmental and biological parameters interact to affect diel O2 saturation and delta18O-O2 curves, thereby providing a fundamental framework for the use of delta18O-O2 in ecosystem productivity studies. delta18O-O2 provides information unavailable from concentration alone because delta18O-O2 and saturation curves are not symmetrical and can be used to constrain gas exchange and isotopic fractionation by eliminating many common assumptions. Changes in key parameters affect diel O2 saturation and delta18O-O2 curves as follows: (1) an increase in primary production and respiration rates increases the diel range of O2 saturation and delta18O-O2 and decreases the mean delta18O-O2 value; (2) a decrease in the primary production to respiration ratio (P:R) decreases the level of O2 saturation and increases the delta18O-O2 values; (3) an increase in the gas exchange rate decreases the diel range of O2 saturation and delta18O-O2 values and moves the mean O2 saturation and delta18O-O2 values toward atmospheric equilibrium; (4) a decrease in strength of the respiratory isotopic fractionation (alphaR closer to 1) has no effect on O2 saturation and decreases the delta18O-O2 values; (5) an increase in the delta18O of water has no effect on O2 saturation and increases the minimum (daytime) delta18O-O2 value; and (6) an increase in temperature reduces O2 solubility and thus increases the diel range of O2 saturation and delta18O-O2 values. Understanding the interplay between these key parameters makes it easier to decipher the controls on O2 and delta18O-O2, compare aquatic ecosystems, and make quantitative estimates of ecosystem metabolism. The photosynthesis to respiration to gas exchange ratio (P:R:G) is better than the P:R ratio at describing and assessing the vulnerability of aquatic ecosystems under various environmental stressors by providing better constrained estimates of ecosystem metabolism and gas exchange.     

Daytime air pollution transport mechanisms in stable atmospheres of narrow versus wide urban valleys

Transport of air pollutants emitted from urban valleys can be strongly restricted by interactions between static and dynamic factors including topographic forcing, low-level atmospheric stability related to temperature inversions, and urban heat island-induced circulations. Interplay between these processes has a complex and dynamic nature, and is determinant for the evolution of different ventilation mechanisms and the associated impacts on air quality. Here we investigate these transport mechanisms through large eddy simulations using EULAG, an established model for multiscale flows, to simulate an idealized atmospheric environment in narrow versus wide urban valleys during critical conditions for air quality (high atmospheric stability). Our results show how the ventilation of valleys depends on a dynamic (variable during the daytime) balance between interacting and sometimes competing processes related to thermally-driven slope flows, urban heat island-induced flows, and the trapping effect of atmospheric stability; and how valley width affects this balance. Particularly important is that the time-space distribution of pollutants (a passive tracer) varies greatly between both valleys despite having the same urban area and emission rates. These variations lead to pollutants being mostly concentrated in different areas of the narrow and wide valleys. We discuss the mechanisms behind these results and their potential implications for real urban valleys. Further understanding of these mechanisms is crucial for explaining the occurrence of severe air pollution episodes and informing related decision-making processes in urban valleys.

     

Isomer‐specific determination and toxic evaluation of potentially hazardous coplanar PCBs,dibenzofurans and dioxins in the tissues of “Yusho” PCB poisoning victim and in the causal oil

In the light of new discoveries on the extremely toxic non‐ortho coplanar 3,3’,4,4'‐tetra‐ (T₄CB), 3,3’,4,4’,5‐penta‐(P₅CB) and 3,3'4,4’,5,5'‐hexachlorobiphenyl (H₆CB) and their mono‐ and di‐ortho analogs, tissue samples of a Yusho poisoning victim and Yusho causal oils were subjected to a thorough congener/isomer‐specific investigation for polychlorinated biphenyls (PCBs), polychlorinated dibenzofurans (PCDFs), polychlorinated dibenzo‐p‐dioxins (PCDDs). Among the many PCB congeners detected in Yusho oil, non‐ortho coplanar T₄CB constituted 3.1%, P₅CB‐0.17% and H₆CB‐0.0072% in total PCBs. Their concentrations in liver and adipose tissue were 130–700 (T₄CB), 54–720 (P₅CB) and 50–380 (H₆CB) pg/g on wet weight basis. The observed concentrations in adipose tissue were two to four fold higher than that detected in unexposed individuals. Among the PCDFs identified, toxic 2,3,7,8‐substituted isomers including 2,3,4,7,8‐P₅CDF were the dominant ones. Tetra‐ through hepta‐CDDs were detected in the oil, whereas octa‐CDD was the dominant isomer in the patient. A comparison with KC‐400 revealed enrichment of coplanar PCBs in Yusho oil along with toxic PCDFs. Enrichment was highest for 3,3'4,4'5,5'‐H₆CB followed by 3,3’,4,4'5‐P₅CB. A comparative toxic evaluation of these chemical groups in Yusho patient's adipose tissue based on “2,3,7,8‐T₄CDD Toxic Equivalent Analysis” revealed accountable toxic contribution from coplanar PCBs. This analysis also confirmed that 2,3,4,7,8‐P₅CDF was the principal causative agent in Yusho poisoning.     

Neue Bewertung bei den Toxizitätsäquivalenten für Dioxine/Furane und für PCB durch die WHO

While the large amount of data available makes it possible to provide a statement concerning the effects of PCDD/PCDF on the WHO TEF-reappraisal regarding the observance of dioxin emission values from waste incineration, similar values for PCBs could not be determined accurately or could only be estimated roughly for the WHO, because only limited measurement values are available for these substances. Thanks to the present availability of such measurement values from the MVA in Bielefeld-Herford, Germany and the MVR in Hamburg, Germany, it is now possible to determine a direct relationship between the low PCDD/PCDF values and the 12 different PCBs which are taken into consideration by the WHO. As the results of these investigations have shown, the statement in Section 2 claiming that there are generally only very low levels of PCDD/PCDF emissions stemming from waste incineration plants, and that the 12 additional PCBs considered by the WHO as well as the WHO TEFs lead to no relevant increase in the evaluation/calculation of the actual emission values nor to a value above the dioxin (I-TEQ) threshold value as established in the 17th BImSchV (Germany Federal regulations responsible for protecting the population from emissions), can be confirmed. A dominant role of the WHO PCB-TEQs is seen to be played by the PCB-126. The exhaust gas measurements in waste incineration plants might therefore already be sufficient if merely the dioxin-like PCB-126 values were to be used in the calculation of the dioxin I-TEQ.     

Identification and assessment of environmental burdens of Chinese copper production from a life cycle perspective

The environmental burdens of Chinese copper production have been identified and quantified in the context of typical technologies, materials supplies and environmental emissions by a life cycle approach. Primary and secondary copper production using copper ores and scraps, respectively, were analyzed in detail. The flash and bath smelting approaches and the recycling of copper scraps were selected as representative copper production processes. A quantitative analysis was also conducted to assess the influence of material transport distance in copper production. Life cycle assessment （LCA） results showed that resources depletion and human health contribute significantly to environmental burdens in Chinese copper production. In addition, the secondary copper production has dramatically lower environmental burdens than the primary production. There is no obvious distinction in overall environmental burdens in primary copper production by flash or bath smelting approach. However, resources depletion is lower and the damage to human health is higher for flash smelting approach. Ecosystem quality damage is slight for both approaches. Environ- mental burdens from the mining stage contribute most in all life cycle stages in primary copper production. In secondary copper production, the electrolytic refining stage dominates. Based on the life cycle assessment results, some suggestions for improving environmental performance were proposed to meet the sustainable development of Chinese copper industry.     

Gas-phase and aerosol chemistry interactions in South Europe and the Mediterranean region

The atmospheric chemical composition is affected by the interaction mechanisms among gases and particulate matter through a wide range of chemical reactions that can occur with the aid of particulate matter (e.g. particles act as reacting or absorbing surfaces) or be influenced by the presence of particulate matter in the atmosphere (photochemical reactions). Physical and chemical processes are also bonded in an interactive way that often leads to the influence of the radiation budget, cloud physics and the warming or cooling of the lower atmospheric levels. The Euro-Mediterranean region is a key-sensitive area due to the unique climatic and air quality characteristics associated with the regional climatic patterns, geomorphology (land and water contrast) and coexistence of pollutants from different origin. Focusing on this region, the gas-aerosol interactions are studied using state-of-the-art atmospheric and chemical transport modeling tools following the necessary development in the chemical transport model CAMx. Sensitivity and large-scale simulations have shown significant responses of the modeling system to the inclusion of natural species emissions, the direct shading effect of dust particles on photochemical processes and the formation of new types of aerosols through heterogeneous uptake of gases on dust particles. Including such interactions in the chemical transport model often led to the improvement of the model performance compared with available measurements in the region.     

29 % N2O emission reduction from a modelled low-greenhouse gas cropping system during 2009–2011

Atmospheric concentration of nitrous oxide (N₂O), a greenhouse gas (GHG), is rising largely due to agriculture. At the plot scale, N₂O emissions from crops are known to be controlled by local agricultural practices such as fertilisation, tillage and residue management. However, knowledge of greenhouse gas emissions at the scale of the cropping system is scarce, notably because N₂O monitoring is time consuming. Strategies to reduce impact of farming on climate should therefore be sought at the cropping system level. Agro-ecosystem models are simple alternative means to estimate N₂O emissions. Here, we combined ecosystem modelling and field measurements to assess the effect of agronomic management on N₂O emissions. The model was tested with series of daily to monthly N₂O emission data. It was then used to evaluate the N₂O abatement potential of a low-emission system designed to halve greenhouse gas emissions in comparison with a system with high productivity and environmental performance. We found a 29 % N₂O abatement potential for the low-emission system compared with the high-productivity system. Among N₂O abatement options, reduction in mineral fertiliser inputs was the most effective.     

A novel strategy for gas mitigation during swine manure odour treatment using seaweed and a microbial consortium

• Comprehensive mitigation of gas emissions from swine manure was investigated. • Additives addition for mitigation of gas from the manure has been developed. • Sargassum horneri, seaweed masking strategy controlled gas by 90%-100%. • Immediate reduction in emitted gas and improving air quality has been determined. • Microbial consortium with seaweed completely controlled gas emissions by 100%. Gas emissions from swine farms have an impact on air quality in the Republic of Korea. Swine manure stored in deep pits for a long time is a major source of harmful gas emissions. Therefore, we evaluated the mitigation of emissions of ammonia (NH₃), hydrogen sulfide (H₂S) and amine gases from swine manure with biological products such as seaweed (Sargassum horneri) and a microbial consortium (Bacillus subtilis (1.2 × 10⁹ CFU/mL), Thiobacillus sp. (1.0 × 10¹⁰ CFU/mL) and Saccharomyces cerevisiae (2.0 × 10⁹ CFU/mL)) used as additives due to their promising benefits for nutrient cycling. Overall, seaweed powder masking over two days provided notable control of over 98%-100% of the gas emissions. Furthermore, significant control of gas emissions was especially pronounced when seaweed powder masking along with a microbial consortium was applied, resulting in a gas reduction rate of 100% for NH₃, amines and H₂S over 10 days of treatment. The results also suggested that seaweed powder masking and a microbial consortium used in combination to reduce the gas emissions from swine manure reduced odour compared with that observed when the two additives were used alone. Without the consortium, seaweed decreased total volatile fatty acid (VFA) production. The proposed novel method of masking with a microbial consortium is promising for mitigating hazardous gases, simple, and environmentally beneficial. More research is warranted to determine the mechanisms underlying the seaweed and substrate interactions.     

Metal transport phases in rivers around Jameshedpur†

Transport phases of four metals of geochemical and water quality importance were investigated in rivers around Jamshedpur. The metals iron, manganese, zinc and copper were partitioned into dissolved, adsorbed and or ion exchangeable, solid organic, oxide coating and crystalline phases applying filtration for the dissolved phase and a chemical fractionation scheme for the particulates. Iron and copper were transported mainly in the particulate phases at all sites, while manganese and zinc were found in the dissolved phase up to a hundred percent depending on the pH of water sample and pollution at the site concerned. Except copper more than 75 percent of all other three metals occurred in transport modes thought to be available to aqueous and biotic interactions. Copper was in available phases from 50 to 70 percent. The significance of metal partitioning as a factor in controlling metal availability and toxicity to biota is discussed.     

The Influence of Varying Planktonic and Periphytic Algal Biomass On Exposure to Polychlorinated Biphenyls in Mesocosms

Algal populations, either suspended in the water column (planktonic) or present on the walls of an enclosure (periphytic), develop differently depending upon the physical scale of the system. This study determined whether these variations altered the speciation and therefore exposure of polychlorinated biphenyls (PCBs) in estuarine mesocosms. Exposure was defined as the fraction of applied contaminant taken up by plankton after two hours. Using a three phase equilibrium model, the partitioning of a suite of PCBs within variously-sized mesocosms was predicted using laboratory derived distribution coefficients and measured levels of planktonic and periphytic algal biomass. in mesocosms having large wall surface area to volume ratios, sorption of hydrophobic PCBs to periphyton significantly decreased contaminant exposure. However, within the range of planktonic algal biomasses observed in this study, the regulation of PCB exposure was relatively invariant between variously-sized mesocosms. to minimize sorption of hydrophobic organic contaminants (HOCs) to periphyton and reduce artefacts inherent with this partitioning, we suggest using mesocosms with low wall surface area to volume ratios (less than or equal to 1). in addition, periphytic biomass should be quantified regularly and a three-phase equilibrium approach used to predict the actual exposure concentrations.