Organocopper complexes during roxarsone degradation in wastewater lagoons

Background, aim, and scope  

Organoarsenical-containing animal feeds that promote growth and resistance to parasites are mostly excreted unchanged, ending up in nearby wastewater storage lagoons. Earlier work documented the partial transformation of organoarsenicals, such as, 3-nitro-4-hydroxyphenylarsonic acid (roxarsone) to the more toxic inorganic arsenate [As(V)] and 3-amino-4-hydroxyphenylarsonic acid (3-AHPAA). Unidentified roxarsone metabolites using liquid chromatography coupled to inductively coupled plasma mass spectrometry (LC/ICP-MS) were also inferred from the corresponding As mass balance. Earlier batch experiments in our laboratory suggested the presence of organometallic (Cu) complexes during relevant roxarsone degradation experiments. We hypothesized that organocopper compounds were complexed to roxarsone, mediating its degradation in field-collected swine wastewater samples from storage lagoons. The objective of this study was to investigate the role of organometallic (Cu) complexes during roxarsone degradation under aerobic conditions in swine wastewater suspensions, using electrospray ionization mass spectrometry (ES-MS).     

Patinas developed in environmental burial conditions: the Neolithic steles of Reguers de Seró (Lleida,Spain)

Background, aim and scope  

Weathering patinas in rocks are the result of interaction processes between rock surfaces and atmosphere, biosphere and soil. Therefore, their textural and mineral composition is strongly related to environmental and bioactivity conditions. Whereas the development of weathering patinas in atmospheric conditions is well documented (e.g. typical Mediterranean patina), only very few studies focus on their formation in a burial environment. Our study of patinas developed on the tumular structure of Reguers de Seró deals with the knowledge of burial patinas from a textural and mineralogical point of view. The aims of this study include: (1) the characterisation of the rock used in this megalithic monument as well as inferences regarding the origin of the raw material; (2) the evaluation of the patinas developed on the surface of the carved steles; and (3) the discussion of the environmental conditions (atmospheric or burial) that favoured the development of the patinas.     

Potential physiological effects of pharmaceutical compounds in Atlantic salmon (<Emphasis Type="Italic">Salmo salar</Emphasis>) implied by transcriptomic analysis

Background, aim, and scope  

Pharmaceuticals are emerging pollutants widely used in everyday urban activities which can be detected in surface, ground, and drinking waters. Their presence is derived from consumption of medicines, disposal of expired medications, release of treated and untreated urban effluents, and from the pharmaceutical industry. Their growing use has become an alarming environmental problem which potentially will become dangerous in the future. However, there is still a lack of knowledge about long-term effects in non-target organisms as well as for human health. Toxicity testing has indicated a relatively low acute toxicity to fish species, but no information is available on possible sublethal effects. This study provides data on the physiological pathways involved in the exposure of Atlantic salmon as representative test species to three pharmaceutical compounds found in ground, surface, and drinking waters based on the evaluation of the xenobiotic-induced impairment resulting in the activation and silencing of specific genes.     

TiO2光催化对微滤去除腐殖酸的膜污染控制研究

着重研究了不同紫外灯光源和照射时间条件下,TiO2光催化（PCO）对微滤去除腐殖酸过程中的膜污染控制,并探讨了膜污染的控制机理。研究结果表明,TiO2光催化能有效提高微滤对腐殖酸的去除,同时降低膜通量的下降,起到有效控制膜污染的作用。进一步的实验分析表明,TiO2光催化控制膜污染的主要机理在于将腐殖酸降解为易于被TiO2吸附的小分子量物质,吸附腐殖酸降解产物后的TiO2聚合颗粒粒径增大,易于在膜表面形成更为松散的沉积层,并使膜污染从以膜孔堵塞和沉积层污染为主转化为以沉积层污染为主的可逆性污染。     

Improvements to lawn and garden equipment emissions estimates for Baltimore, Maryland

Lawn and garden equipment are a significant source of emissions of volatile organic compounds (VOCs) and other pollutants in suburban and urban areas. Emission estimates for this source category are typically prepared using default equipment populations and activity data contained in emissions models such as the U.S. Environmental Protection Agency's (EPA) NONROAD model or the California Air Resources Board's (CARB) OFFROAD model. Although such default data may represent national or state averages, these data are unlikely to reflect regional or local differences in equipment usage patterns because of variations in climate, lot sizes, and other variables. To assess potential errors in lawn and garden equipment emission estimates produced by the NONROAD model and to demonstrate methods that can be used by local planning agencies to improve those emission estimates, this study used bottom-up data collection techniques in the Baltimore metropolitan area to develop local equipment population, activity, and temporal data for lawn and garden equipment in the area. Results of this study show that emission estimates of VOCs, particulate matter (PM), carbon monoxide (CO), carbon dioxide (CO2), and nitrogen oxides (NO(x)) for the Baltimore area that are based on local data collected through surveys of residential and commercial lawn and garden equipment users are 24-56% lower than estimates produced using NONROAD default data, largely because of a difference in equipment populations for high-usage commercial applications. Survey-derived emission estimates of PM and VOCs are 24 and 26% lower than NONROAD default estimates, respectively, whereas survey-derived emission estimates for CO, CO2, and NO(x) are more than 40% lower than NONROAD default estimates. In addition, study results show that the temporal allocation factors applied to residential lawn and garden equipment in the NONROAD model underestimated weekend activity levels by 30% compared with survey-derived temporal profiles.     

Nocturnal boundary layer characteristics and land breeze development in Houston,Texas during TexAQS II

The nocturnal boundary layer in Houston, Texas was studied using a high temporal and vertical resolution tethersonde system on four nights during the Texas Air Quality Study II (TexAQS II) in August and September 2006. The launch site was on the University of Houston campus located approximately 4 km from downtown Houston. Of particular interest was the evolution of the nocturnal surface inversion and the wind flows within the boundary layer. The land–sea breeze oscillation in Houston has important implications for air quality as the cycle can impact ozone concentrations through pollutant advection and recirculation. The results showed that a weakly stable surface inversion averaging in depth between 145 and 200 m AGL formed on each of the experiment nights, typically within 2–3 h after sunset. Tethersonde vertical winds were compared with two other Houston data sets (High Resolution Doppler Lidar and radar wind profiler) from locations near the coastline and good agreement was found, albeit with a temporal lag at the tethersonde site. This comparison revealed development of a land breeze on three nights which began near the coastline and propagated inland both horizontally and vertically with time. The vertical temperature structure was significantly modified on one night at the tethersonde site after the land breeze wind shift, exhibiting near-adiabatic profiles below 100 m AGL.     

Why ozonolysis may not increase the hydrophilicity of particles

It is commonly assumed that atmospheric oxidation of hydrocarbon particles or hydrocarbon coatings on particles leads to polar products and increased water uptake, altering atmospheric visibility and increasing the likelihood they will act as cloud condensation nuclei (CCN). We show here through laboratory experiments that increased water uptake depends on the 3-dimensional structure of the particles. Laboratory studies of particles formed during ozonolysis of surface-bound alkenes, present as terminally unsaturated self-assembled monolayers (C8= SAM) on a silica substrate, were carried out at room temperature and 1 atm pressure. SAMs were exposed to ～10¹³ O₃ molecules cm^?3 for 40 min and resultant particles were analyzed using single particle Fourier transform infrared micro-spectroscopy (micro-FTIR) and secondary ion mass spectroscopy (SIMS). Spectroscopy results show that –COOH and other polar groups are formed but are buried inside a hydrophobic shell, consistent with earlier observations (McIntire et al., 2005, Moussa et al., 2009) that water uptake does not increase after reaction of the terminal alkene with O₃. These insights into the 3-D structure of particles formed on oxidation have important implications for the ability of secondary organic aerosols to act as CCN. In addition, the nature of the surface of the particles is expected to determine their uptake into biological systems such as the surface of the lungs.     

Improved land cover and emission factors for modeling biogenic volatile organic compounds emissions from Hong Kong

This paper describes a study of local biogenic volatile organic compounds (BVOC) emissions from the Hong Kong Special Administrative Region (HKSAR). An improved land cover and emission factor database was developed to estimate Hong Kong emissions using MEGAN, a BVOC emission model developed by Guenther et al. (2006). Field surveys of plant species composition and laboratory measurements of emission factors were combined with other data to improve existing land cover and emission factor data. The BVOC emissions from Hong Kong were calculated for 12 consecutive years from 1995 to 2006. For the year 2006, the total annual BVOC emissions were determined to be 12,400 metric tons or 9.82 × 10⁹ g C (BVOC carbon). Isoprene emission accounts for 72%, monoterpene emissions account for 8%, and other VOCs emissions account for the remaining 20%. As expected, seasonal variation results in a higher emission in the summer and a lower emission in the winter, with emission predominantly in day time. A high emission of isoprene occurs for regions, such as Lowest Forest-NT North, dominated by broadleaf trees. The spatial variation of total BVOC is similar to the isoprene spatial variation due to its high contribution. The year to year variability in emissions due to weather was small over the twelve-year period (?1.4%, 2006 to 1995 trendline), but an increasing trend in the annual variation due to an increase in forest land cover can be observed (+7%, 2006 to 1995 trendline). The results of this study demonstrate the importance of accurate land cover inputs for biogenic emission models and indicate that land cover change should be considered for these models.     

The application of profluorescent nitroxides to detect reactive oxygen species derived from combustion-generated particulate matter: Cigarette smoke – A case study

Reactive oxygen species (ROS) and related free radicals are considered to be key factors underpinning the various adverse health effects associated with exposure to ambient particulate matter. Therefore, measurement of ROS is a crucial factor for assessing the potential toxicity of particles. In this work, a novel profluorescent nitroxide, BPEAnit, was investigated as a probe for detecting particle-derived ROS. BPEAnit has a very low fluorescence emission due to inherent quenching by the nitroxide group, but upon radical trapping or redox activity, a strong fluorescence is observed. BPEAnit was tested for detection of ROS present in mainstream and sidestream cigarette smoke. In the case of mainstream cigarette smoke, there was a linear increase in fluorescence intensity with an increasing number of cigarette puffs, equivalent to an average of 101 nmol ROS per cigarette based on the number of moles of the probe reacted. Sidestream cigarette smoke sampled from an environmental chamber exposed BPEAnit to much lower concentrations of particles, but still resulted in a clearly detectible increase in fluorescence intensity with sampling time. It was calculated that the amount of ROS was equivalent to 50 ± 2 nmol per mg of particulate matter; however, this value decreased with ageing of the particles in the chamber. Overall, BPEAnit was shown to provide a sensitive response related to the oxidative capacity of the particulate matter. These findings present a good basis for employing the new BPEAnit probe for the investigation of particle-related ROS generated from cigarette smoke as well as from other combustion sources.