使食品生产变得可持续

就满足一个人口日益增加的世界的营养需要而言,自然资源基础是有限的和脆弱的,而且不可持续的生产和消费方式还在蔓延:这是21世纪的挑战!迄今为止,人类的聪明才智一直设法寻求全球规模上的平衡--如果通常并非地区性或地方性平衡的话.但所使用的方法并不是可持续的.需要深入评议生产、供应和需求链上的所有步骤.     

Chemisch-analytische Untersuchung von Arsenkampfstoffen und ihren Metaboliten

Arsenic containing chemical warfare agents (cwa) are persistent in the environment and continue to contaminte soil and ground water. In this paper the chemical rections of the cwa diphenylarsine chloride (CLARK I), phenylarsine dichloride (PFIFFIKUS), ethylarsine dichloride (DICK) and of chlorovinyl arsenic compounds (LEWISITE) are shown. The posibilities of the detection and determination of this cwa and their metabolites are presented.     

成都市大气颗粒物粒径分布及其对能见度的影响

使用环境颗粒物分析仪（GRIMM180）对成都市2018年10月—2019年9月0.25~32 μm的大气颗粒物数浓度粒径分布进行观测,结合细颗粒物（PM_2.5）质量浓度以及相对湿度（RH）、能见度、降水量等气象要素数据,分析了成都市大气颗粒物粒径分布及其与能见度的关系.结果表明,观测期间成都市大气颗粒物以细粒子为主,0.25~0.5 μm的粒子数浓度占总数浓度的97.75%,数浓度谱呈单峰分布,2018年秋季、2019年夏季表面积谱呈双峰分布,2018年冬季、2019年春季表面积谱呈三峰,体积谱均为三峰分布;在不同RH区间,PM_2.5质量浓度及数浓度均与能见度呈负相关,且其中0.25~0.5 μm粒径段的细颗粒物因为对可见光波段的米散射效应而对能见度产生较大影响;在不同RH情况下,不同粒径段颗粒物数浓度对能见度的影响程度有所差别：在低RH（<70%）下,0.25~0.3 μm粒径段粒子数浓度对能见度影响最大;在中等RH（70%~80%）下,0.3~0.5 μm粒径段粒子数浓度对能见度的影响最大;而在高RH（>80%）下,0.3~0.5 μm和0.5~1 μm粒径段粒子数浓度对能见度影响相当.     

厌氧条件下砂壤水稻土N2、N2O、NO、CO2和CH4排放特征

了解厌氧条件土壤反硝化气体(N2、N2O和NO)、CO2和CH4排放特征,是认识反硝化过程机制的基础,并有助于制定合理的温室气体减排措施.定量反硝化产物组成,可为氮转化过程模型研发制定正确的关键过程参数选取方法或参数化方案.本研究选取质地相同(砂壤土)的两个水稻土为研究对象,通过添加KNO3和葡萄糖的混合溶液,将培养土壤的初始NO-3和DOC含量分别调节到50 mg·kg-1和300 mg·kg-1,采用氦环境培养-气体及碳氮底物直接同步测定方法,研究完全厌氧条件下土壤N2、N2O、NO、CO2和CH4的排放特征,并获得反硝化气态产物中各组分的比率.结果表明,在整个培养过程中,两个供试土壤的N2、N2O和NO累积排放量分别为6~8、20和15~18 mg·kg-1,这些气体排放量测定结果可回收土壤NO-3变化量的95%~98%,反硝化气态产物以N2O和NO为主,其中3种组分的比率分别为15%~19%(N2)、47%~49%(N2O)和34%~36%(NO);但反硝化气体产物组成的逐日动态均显现为从以NO为主逐渐过渡到以N2O为主,最后才发展到以N2为主.以上结果说明,反硝化气体产物组成是随反硝化进程而变化的,在以气体产物组成比率作为关键参数计算各种反硝化气体产生率或排放率的模型中,很有必要重视这一点.     

Benzyl-penicillin (Penicillin G) transformation in aqueous solution at low temperature under controlled laboratory conditions

Antibiotics are released into the environment in a variety of ways: via wastewater effluent as a result of incomplete metabolism in the body after use in human therapy, as runoff after use in agriculture, through improper disposal by private households or hospitals or through insufficient removal by water treatment plants. Unlike in most European countries, in Arctic regions effluents are not suitably treated prior to their release into the aquatic environment. Also, many of the scattered human settlements in remote regions of the Arctic do not possess sewage treatment facilities and pharmaceutical residues therefore enter the aqueous environment untreated. Only limited data are available on the biodegradation of antibiotics under Arctic conditions. However, such information is needed to estimate the potential harm of antibiotics for the environment. Pen-G is used in this study since it is a widely prescribed antibiotic compound whose environmental properties have not yet been investigated in detail. Thus, for a very first assessment, the OECD approved biodegradation Zahn-Wellens test (ZWT, OECD 302 B) was used to study biodegradation and non-biotic elimination of the antibiotic Benzyl-penicillin (Pen-G) at different temperatures (5°C, 12.5°C and 20°C). The testing period was extended from the OECD standard of 28-42d. In addition to dissolved organic carbon (DOC), Pen-G levels and major transformation products were recorded continuously by LC-ion-trap-MS/MS. DOC monitoring revealed considerable temperature dependence for the degradation process of Pen-G. DOC loss was slowest at 5°C and considerably faster at 12.5°C and 20°C. In the initial step of degradation it was found that Pen-G was hydrolyzed. This hydrolyzed Pen-G was subsequently further degraded by decarboxylation, the result of which was 2-(5,5-dimethyl-1,3-thiazolidin-2-yl)-2-(2-phenylacetamido)acetic acid. Furthermore, direct elimination of 2-phenyl-acetaldehyde from the hydrolyzed and decarboxylated Pen-G also led to the formation of 2-[amino(carboxy)methyl]-5,5-dimethyl-1,3-thiazolidone-4-carboxylic acid. Since biodegradation slows down considerably at a low temperature, the resulting transformation products had considerably longer residence times at 5°C compared to higher temperature conditions within the 42-d experiment. The results presented here clearly demonstrate that a risk assessment for pharmaceuticals present in low ambient temperature environments (i.e. the Arctic) cannot be based on test results obtained under standard laboratory conditions (i.e. 20°C ambient temperatures).     

Volatile nanoparticle formation and growth within a diluting diesel car exhaust

A major source of particle number emissions is road traffic. However, scientific knowledge concerning secondary particle formation and growth of ultrafine particles within vehicle exhaust plumes is still very limited. Volatile nanoparticle formation and subsequent growth conditions were analyzed here to gain a better understanding of "real-world" dilution conditions. Coupled computational fluid dynamics and aerosol microphysics models together with measured size distributions within the exhaust plume of a diesel car were used. The impact of soot particles on nucleation, acting as a condensational sink, and the possible role of low-volatile organic components in growth were assessed. A prescribed reduction of soot particle emissions by 2 orders of magnitude (to capture the effect of a diesel particle filter) resulted in concentrations of nucleation-mode particles within the exhaust plume that were approximately 1 order of magnitude larger. Simulations for simplified sulfuric acid-water vapor gas-oil containing nucleation-mode particles show that the largest particle growth is located in a recirculation zone in the wake of the car. Growth of particles within the vehicle exhaust plume up to detectable size depends crucially on the relationship between the mass rate of gaseous precursor emissions and rapid dilution. Chassis dynamometer measurements indicate that emissions of possible hydrocarbon precursors are significantly enhanced under high engine load conditions and high engine speed. On the basis of results obtained for a diesel passenger car, the contributions from light diesel vehicles to the observed abundance of measured nucleation-mode particles near busy roads might be attributable to the impact of two different time scales: (1) a short one within the plume, marked by sufficient precursor emissions and rapid dilution; and (2) a second and comparatively long time scale resulting from the mix of different precursor sources and the impact of atmospheric chemistry.     

Anaerobic inhibition and biodegradation of antibiotics in ISO test schemes

Municipal sewage is the main exposure route for antibiotics that are used in human medical care. Antibiotics that adsorb to the primary sludge and/or sur-plus activated sludge will enter the anaerobic digesters of municipal sewage treatment plants. Here anaerobic biodegradation or inhibition of anaerobic bacteria resulting in a disturbance of the process might occur. ISO standards 13641 (2003) and 11734 (1999) were used for assessing the anaerobic inhibition of 16 and the anaerobic biodegradability of 9 antibiotics respectively. Digestion sludge from a municipal sewage treatment plant (1g/l d.s.) was used as inoculum in both tests. In ISO 13641 (2003) most antibiotics showed only moderate inhibition effects after a 7 day incubation period, with EC50 values between 24 mg/l and more than 1000 mg/l (equal to mg/g d.s.). In contrast, metronidazol was decisively toxic to anaerobic bacteria with an EC50 of 0.7 mg/l. In the anaerobic degradation tests according to ISO standard 11734 (1995), only benzylpenicillin showed certain ultimate biodegradation after 60 days and most antibiotics inhibited the digesting sludge in the respective parallel tested inhibition controls. Thus the inhibition of anaerobic bacteria by antibiotics observed in the degradation tests was higher than expected from the results of the inhibition tests. The possible explanations are that distinct substrates are used (yeast extract versus sodium benzoate), that the digestion sludge loses activity during the washing steps performed for the degradation tests and that the exposure time in the degradation tests was 8 times longer than in the inhibition test.     

Using Wet-FGD systems for mercury removal

A plan to control mercury emissions to the atmosphere and to establish mercury emission limits has recently been elaborated by the European Commission, making it necessary to devise an efficient and cost effective mercury removal technology. Towards this end wet flue gas desulfurization units appear as a promising option for multi-pollutant control. However, more investigation on mercury removal and a greater mercury removal efficiency are required to achieve this objective. In the present work scrubber chemistry and the application of various solid additives to enhance mercury removal in wet scrubbers is evaluated. The results obtained show a significant correlation between mercury removal efficiency and the pH of the scrubber slurry and SO2 concentration. A weaker correlation was observed between oxygen or slurry concentration and removal efficiency. Finally several solid oxides were found to be effective additives for enhancing mercury capture in wet scrubbers.     

Vertical profile of PCDD/Fs, dioxin-like PCBs, other PCBs, PAHs, chlorobenzenes, DDX, HCHs, organotin compounds and chlorinated ethers in dated sediment/soil cores from flood-plains of the river Elbe, Germany

Concentrations of polychlorinated dibenzo-p-dioxins (PCDDs) and dibenzofurans (PCDFs) and other organic micropollutants were determined in dated sediment/soil cores collected from the flood-plain of the river Elbe near Pevestorf (PT), approximately 125 km upstream of Hamburg, and Heuckenlock (HL) in southeast of Hamburg. Concentrations of PCDD/Fs peaked sharply at PT in the 1950s and at HL at the end of the 1940s. Cluster analyses provide evidence that the region of Bitterfeld-Wolfen (about 350-400 km upstream of Hamburg) could be the source of the PCDD/F contamination existing in the cores PT and HL since the 1940s. Obviously it is caused by sediments of the river Elbe of a similar composition. Whereas the PCDD/Fs, HCHs (hexacyclohexane isomers), DDX (DDT, DDD, DDE), and tetrachlorinated ethers in PT and HL presumably originated predominantly from the Bitterfeld-Wolfen region, organotin compounds in HL and dichlorinated haloethers in HL during the 1940s and 1950s can probably largely be attributed to emissions from the Hamburg region. Although they are separated by a large distance, in both sediment cores PT and HL concentrations and composition patterns of most organic micropollutants analyzed widely match. Inductively it can be concluded that similar contaminations will be found in many of the river bank soils between the Bitterfeld-Wolfen region and Hamburg. Excavation of top soils may uncover highly contaminated materials. Since the dated sediment cores show the variation in contaminants in the Elbe sediments over a defined time period, it is possible to make an approximate assessment of the actual degree of contamination to be expected in areas where in previous decades contaminated dredged sediments from the Elbe and from the Port of Hamburg have been deposited on land and used for building plots or for agricultural purposes.