Ecosystem responses to climate change at a Low Arctic and a High Arctic long-term research site

Long-term measurements of ecological effects of warming are often not statistically significant because of annual variability or signal noise. These are reduced in indicators that filter or reduce the noise around the signal and allow effects of climate warming to emerge. In this way, certain indicators act as medium pass filters integrating the signal over years-to-decades. In the Alaskan Arctic, the 25-year record of warming of air temperature revealed no significant trend, yet environmental and ecological changes prove that warming is affecting the ecosystem. The useful indicators are deep permafrost temperatures, vegetation and shrub biomass, satellite measures of canopy reflectance (NDVI), and chemical measures of soil weathering. In contrast, the 18-year record in the Greenland Arctic revealed an extremely high summer air-warming of 1.3 °C/decade; the cover of some plant species increased while the cover of others decreased. Useful indicators of change are NDVI and the active layer thickness.     

美国和五大湖双边共同关注区域的白肚燕(双色树燕)雏鸟的有机污染状况

白肚燕,又名双色树燕,栖居于五大湖流域中27个双边共同关注区域(AOCs),从2010年到2014年对其进行了污染物暴露风险评估,以协助管理者和监管者评估五大湖AOCs的污染状况。本文比较了AOCs和附近非AOCs雏鸟体内污染物浓度的差异。AOCs白肚燕雏鸟尸体中多氯联苯(PCB)和多溴联苯醚的含量分别为30%和33%,低于非AOCs的平均浓度。AOCs白肚燕雏鸟胃含物中多环芳烃(PAH)浓度和血浆中全氟化合物浓度分别为67%和64%,也低于非AOCs的平均浓度。但是与已有生殖效应记载的高PCB污染区相比,有些AOCs雏鸟尸体内的PCBs浓度只是存在小幅升高。一些AOCs食物中PAHs的浓度足够高以致引起可测量的生理响应。在AOCs中,全氟化合物全氟辛烷磺酸在血浆中的最高浓度出现在Raisin河(密歇根州,美国;几何平均数330 ng/mL),但远低于预估毒性的参考值(1 700 ng/mL)。之前有研究报道雏鸟胃含物中PAH和PCB的浓度以及尸体中PCBs的含量与沉积物中污染物的含量显著相关,从而可加强白肚燕在评估沉积物污染生物有效性方面的应用。
精选自Thomas W. Custer, Christine M. Custer, Paul M. Dummer, Diana Goldberg, J. Christian Franson, Richard A. Erickson. Organic contamination in tree swallow (Tachycineta bicolor) nestlings at United States and binational Great Lakes areas of concern. Environmental Toxicology and Chemistry: Volume 36, Issue 3, pages 735–748, July 2017. DOI: 10.1002/etc.3598
详情请见http://onlinelibrary.wiley.com/wol1/doi/10.1002/etc.3598/full
     

Methane biofiltration in the presence of ethanol vapor under steady and transient state conditions: an experimental study

Methane (CH₄) removal in the presence of ethanol vapors was performed by a stone-based bed and a hybrid packing biofilter in parallel. In the absence of ethanol, a methane removal efficiency of 55 ± 1% was obtained for both biofilters under similar CH₄ inlet load (IL) of 13 ± 0.5 g_CH4 m^?3 h^?1 and an empty bed residence time (EBRT) of 6 min. The results proved the key role of the bottom section in both biofilters for simultaneous removal of CH₄ and ethanol. Ethanol vapor was completely eliminated in the bottom sections for an ethanol IL variation between 1 and 11 g_ethanol m^?3 h^?1. Ethanol absorption and accumulation in the biofilm phase as well as ethanol conversion to CO₂ contributed to ethanol removal efficiency of 100%. In the presence of ethanol vapor, CO₂ productions in the bottom section increased almost fourfold in both biofilters. The ethanol concentration in the leachate of the biofilter exceeding 2200 g_ethanol m^?3 _leachate in both biofilters demonstrated the excess accumulation of ethanol in the biofilm phase. The biofilters responded quickly to an ethanol shock load followed by a starvation with 20% decrease of their performance. The return to normal operations in both biofilters after the transient conditions took less than 5 days. Unlike the hybrid packing biofilter, excess pressure drop (up to 1.9 cmH₂O m^?1) was an important concern for the stone bed biofilter. The biomass accumulation in the bottom section of the stone bed biofilter contributed to 80% of the total pressure drop. However, the 14-day starvation reduced the pressure drop to 0.25 cmH₂O m^?1.     

Overview of surface measurements and spatial characterization of submicrometer particulate matter during the DISCOVER-AQ 2013 campaign in Houston,TX

The sources of submicrometer particulate matter (PM₁) remain poorly characterized in the industrialized city of Houston, TX. A mobile sampling approach was used to characterize PM₁ composition and concentration across Houston based on high-time-resolution measurements of nonrefractory PM₁ and trace gases during the DISCOVER-AQ Texas 2013 campaign. Two pollution zones with marked differences in PM₁ levels, character, and dynamics were established based on cluster analysis of organic aerosol mass loadings sampled at 16 sites. The highest PM₁ mass concentrations (average 11.6 ± 5.7 µg/m³) were observed to the northwest of Houston (zone 1), dominated by secondary organic aerosol (SOA) mass likely driven by nighttime biogenic organonitrate formation. Zone 2, an industrial/urban area south/east of Houston, exhibited lower concentrations of PM₁ (average 4.4 ± 3.3 µg/m³), significant organic aerosol (OA) aging, and evidence of primary sulfate emissions. Diurnal patterns and backward-trajectory analyses enable the classification of airmass clusters characterized by distinct PM sources: biogenic SOA, photochemical aged SOA, and primary sulfate emissions from the Houston Ship Channel. Principal component analysis (PCA) indicates that secondary biogenic organonitrates primarily related with monoterpenes are predominant in zone 1 (accounting for 34% of the variability in the data set). The relevance of photochemical processes and industrial and traffic emission sources in zone 2 also is highlighted by PCA, which identifies three factors related with these processes/sources (~50% of the aerosol/trace gas concentration variability). PCA reveals a relatively minor contribution of isoprene to SOA formation in zone 1 and the absence of isoprene-derived aerosol in zone 2. The relevance of industrial amine emissions and the likely contribution of chloride-displaced sea salt aerosol to the observed variability in pollution levels in zone 2 also are captured by PCA.

Implications: This article describes an urban-scale mobile study to characterize spatial variations in submicrometer particulate matter (PM₁) in greater Houston. The data set indicates substantial spatial variations in PM₁ sources/chemistry and elucidates the importance of photochemistry and nighttime oxidant chemistry in producing secondary PM₁. These results emphasize the potential benefits of effective control strategies throughout the region, not only to reduce primary emissions of PM₁ from automobiles and industry but also to reduce the emissions of important secondary PM₁ precursors, including sulfur oxides, nitrogen oxides, ammonia, and volatile organic compounds. Such efforts also could aid in efforts to reduce mixing ratios of ozone.     

Future implications of urban intensification on residential water demand

Over recent decades Auckland, New Zealand, metropolitan area has vastly expanded as a result of rapid population growth and low-density housing developments. In order to manage the uncontrolled low-density urban sprawl, Auckland Council proposed a compact city model through promoting higher density housing developments. In order to understand the implications of this transition on future residential water demand, this study first evaluated water consumption in three major housing types in Auckland including single houses, low-rise and high-rise apartments. Using the geographic information system, the water consumption information, estimated from a large sample of 60,000 dwellings across Auckland, was subsequently integrated with the Proposed Auckland Unitary Plan outlining the future housing composition over different areas in Auckland. Through developing different growth scenarios, the study showed that the housing transition from single houses to more intensified multi-unit houses cannot considerably affect the average per capita water consumption in Auckland.     

Public participation in municipal solid waste source-separated collection in Guilin,China: status and influencing factors

Currently, China is facing critical problems regarding the management of municipal solid waste (MSW). The failure of existing pilot programs in implementing MSW source-separated collection highlights the need to analyze the factors significantly influencing public participation in this activity. To this end, a comprehensive analysis of MSW source-separated collection in Guilin, which is representative of wider areas located in inland China and with a GDP around the national average, was conducted. The research consisted of in-person interviews involving a questionnaire and theoretical analyses in terms of public perception, public awareness, public attitude, and willingness to pay. The analytical results identify the status of waste source-separated collection and influencing factors in implementation, and provides exercisable suggestions for decision makers in both China and more generally in industrializing countries to design promotion programs and education campaigns.     

Industrial pollution,spatial stigma and economic decline: the case of Asopos river basin through the lens of local small business owners

This paper explores the notion of environmentally induced spatial stigma through an analysis of data from interviews across public attitudes to pollution within the Asopos river basin in central Greece. The area has a 40 year plus history of legal and illicit industrial waste disposal and public debate on the associated environmental degradation. The study focuses on the perceptions and beliefs of a sector of the community likely to be directly and negatively affected by stigma, that is small business owners in the tourism and hospitality sector. The qualitative analysis explores awareness and viewpoints on environmental degradation and water quality within the local context, implications for the local economy and the individual's own enterprise, views on industrial environmental management as well as corporate responsibility and future prospects for the environmental problems of Asopos. Findings reveal a noticeable variation in views on industrial pollution and ecosystem deterioration among the respondents, but overall a strong environmentally induced stigmatization of the area. They also uncover an information asymmetry and lack of credible commitment by government bodies and industry members in disclosing accurate information, a situation likely to increase speculation and uncertainty within the community. The paper concludes by addressing implications of the findings to policy-making and managerial considerations, along with future research perspectives which aim to increase considerations of sustainability aspects for local development.     

Glutamine synthetase and protease enzyme activities and growth response of ruminal bacterium Prevotella ruminicola strain B14 to nitrogen source and concentration

Abstract

The objective of this study was to determine the effects of varying nitrogen sources and concentrations upon glutamine synthetase and protease activities in Prevotella ruminicola strain B₁4. Based on growth response it appears that ammonium chloride or pepticase limited P. ruminicola becomes nitrogen limited when nitrogen concentration is at 0.5 mM. However, when casein was provided as the sole source of nitrogen P. ruminicola becomes nitrogen limited at 2.5 mM. Glutamine synthetase activity was measured from mid‐log phase cells grown in either nitrogen‐limited or non‐limited conditions. No activity was detectable in the non‐limited treatments. However, in the N‐ limited treatments, pepticase had the highest activity (20.76 units), followed by ammonium chloride (18.72 units) and casein (14.42 units). Protease activity assays indicated that nitrogen‐limited cultures had higher proteolytic activity than non‐limited cultures. Moreover, these activities appeared to follow the same response pattern as the previously observed glutamine synthetase activities. The results of this study indicate that P. ruminicola strain B, 4 protease activity may be influenced by nitrogen concentration such that activity increases when nitrogen availability decreases.     

Growth Inhibition by Nitrocompounds of Selected Uric Acid-Utilizing Microorganisms Isolated from Poultry Manure

The overall objective of this study was to evaluate the potential ability of nitrocompounds to reduce ammonia volatilization by inhibiting uric acid–utilizing microorganisms. Experiment I was conducted to evaluate the effects of nitrocompounds on the growth of uric acid–utilizing microorganisms isolated from poultry manure during six-hour incubation. There were five treatments: (1) control, (2) 50 mM nitroethane, (3) 50 mM nitroethanol, (4) 50 mM nitropropanol, and (5) 50 mM nitropropionic acid. Optical density values of nitrocompounds were significantly lower than that of control at two, four, and six hours. Plate counts of uric acid–utilizing microorganisms after six-hour incubation exhibited that nitrocompounds greatly reduced the growth of these microorganisms except for the nitroethane (P < 0.05). The nitropropanol and nitropropionic acid treatments showed significantly higher inhibitory effects compared to the nitroethanol. Experiments II and III were conducted to evaluate inhibitory effects of nitrocompounds on growth of uric acid–utilizing microorganisms compared to non-nitrocompounds such as ethanol, propanol, and propionic acid. Experiments II and III consisted of seven treatments: (1) control, (2) nitroethanol, (3) nitropropanol, (4) nitropropionic acid, (5) ethanol, (6) propanol, and (7) propionic acid. The incubation times of Experiments II and III were 6 and 24 h, respectively. The nitrocompounds were significantly more successful in inhibiting growth of uric acid–utilizing microorganisms compared to those non-nitrocompounds. These results suggest that nitrocompounds exhibit potential to reduce ammonia volatilization in poultry manure by inhibiting growth of uric acid–utilizing microorganisms.     

In vitro approaches to assess bioavailability and human gastrointestinal mobilization of food-borne polychlorinated biphenyls (PCBs)

This study reports on the potential for gastrointestinal (GI) mobilization and bioavailability of food-borne PCBs in humans. The development and validation of a GI simulator and operational protocols, developed in compliance with the requirements of German DIN 19738 risk assessment test procedure, are presented. Food, naturally contaminated with PCBs, was homogenized with simulated saliva fluid and shaken in the GI simulator with simulated gastric fluids (containing pepsin, mucine) for 2 h at 37°C. Afterwards, the simulated intestinal fluids (containing pepsin, mucine, trypsin, pancreatin, bile) were added and the mixture shaken for a further 6 h prior to centrifugation and filtration using Buchner funnels to separate the undigested GI residues from GI fluids. PCBs were recovered from GI residues and fluids by Soxhlet and liquid-liquid extraction respectively, cleaned up using silica-SFE, and analyzed by gas chromatography mass spectrometry detection (GC-MSD). Detailed studies with fish indicate variations in mobilization and bioavailability of Σ PCBs (28, 52, 101, 118, 153, 138 and 180). For example, the bioavailable fractions (fractions mobilized) in mackerel, salmon, crab and prawn were 0.77, 0.60, 0.54, and 0.72 respectively of the Σ PCBs initially present in these food samples. The bioavailable fraction was dependent on the physicochemical characteristics of the PCBs. In mackerel bioavailable fractions for individual PCB congeners ranged from 0.47–0.82, from 0.30–0.70 in salmon, 0.44–0.64 in crab and in prawn from 0.47–0.77. Future studies will focus on understanding better, the variability in bioavailable fractions to be expected for different foodstuffs, in addition to tissue culture techniques using human gut cell lines to investigate a simultaneous mobilization and absorption of food-borne PCBs.