A comparison of two techniques for studying sediment desorption kinetics of hydrophobic pollutants

A comparison of two techniques (gaseous purge and vial desorption) for studying the kinetics of desorption of hydrophobic pollutants from natural sediments was conducted using identical, pre-equilibrated pollutant-sediment suspensions. Desorption profiles for the two techniques [for Lindane, Aldrin, 2,2'-dichlorobiphenyl (2,2'-DCB), 4,4'-dichlorobiphenyl (4,4'-DCB), and 2,2',6,6'-tetrachlorobiphenyl (TCB)] were then compared, based on the distribution of pollutant mass between the labile (fast) and non-labile (slow) desorption phases and the release rate constants for each phase of release. The vial desorption technique shows many practical advantages over the gaseous purge technique, including its more realistic mixing conditions, the use of an independent sample for each data point (as opposed to a calculation of a cumulative mass purged at each time point), the fact that the vials constitute a closed system and are therefore less subject to ambient contamination, and the relatively low demands of time and money for the vial technique. No consistent trends in labile rate constants or in pollutant distribution between the labile and non-labile phase were observed between the two techniques. A comparison of kinetic parameters shows much faster non-labile rate constants for the gaseous purge technique, attributed to the violent, continuous agitation employed, which likely disrupted sediment aggregates and oxidized the natural organic matter associated with the sediment. Non-labile rate constants have implications for the long-term fate of compounds adsorbed to repetitively disturbed sediments. This study suggests that the traditionally less popular vial desorption technique may yield more realistic non-labile desorption rate constants.     

Source apportionment of fine particles in Tennessee using a source-oriented model

Source apportionment of fine particles (PM2.5, particulate matter < 2 microm in aerodynamic diameter) is important to identify the source categories that are responsible for the concentrations observed at a particular receptor. Although receptor models have been used to do source apportionment, they do not fully take into account the chemical reactions (including photochemical reactions) involved in the formation of secondary fine particles. Secondary fine particles are formed from photochemical and other reactions involving precursor gases, such as sulfur dioxide, oxides of nitrogen, ammonia, and volatile organic compounds. This paper presents the results of modeling work aimed at developing a source apportionment of primary and secondary PM2.5. On-road mobile source and point source inventories for the state of Tennessee were estimated and compiled. The national emissions inventory for the year 1999 was used for the other states. U.S. Environmental Protection Agency Models3/Community Multi-Scale Air Quality modeling system was used for the photochemical/secondary particulate matter modeling. The modeling domain consisted of a nested 36-12-4-km domain. The 4-km domain covered the entire state of Tennessee. The episode chosen for the modeling runs was August 29 to September 9, 1999. This paper presents the approach used and the results from the modeling and attempts to quantify the contribution of major source categories, such as the on-road mobile sources (including the fugitive dust component) and coal-fired power plants, to observed PM2.5 concentrations in Tennessee. The results of this work will be helpful in policy issues targeted at designing control strategies to meet the PM2.5 National Ambient Air Quality Standards in Tennessee.     

Biodegradability of Poly (lactic acid), Preparation and Characterization of PLA/Gum Arabic Blends

In this study, the biodegradation of PLA films using microorganisms from Lake Bogoria (Kenya) were investigated. The biodegradation tests done using certain strains of thermophilic bacteria showed faster biodegradation rates and demonstrated temperature dependency. The biodegradation of the PLA films was studied using Gel Permeation Chromatography (GPC) and light microscopy. The biodegradation of PLA was demonstrated by decrease in molecular weight. The preparation and characterization of PLA/Gum Arabic blends were also investigated using DSC, TGA, TMA and NMR. In summary, the results obtained in this research show that PLA films undergo fast biodegradation using thermophiles isolated from Lake Bogoria. The PLA/GA blends studies show it is possible to prepare films of varying hydrophobic–hydrophilic properties for various applications.     

Modeling the nexus between coal consumption,FDI inflow and economic expansion: does industrialization matter in South Africa?

Environmental Science and Pollution Research - This study examines the role of industrialization in the energy-growth-FDI nexus for the case of South Africa using data over the period 1970 to 2018....     

Cooling suits, physiological response, and task performance in hot environments for the power industry.

Heat stress on workers working outdoors in the power industry may result in fatigue and deterioration in task performance. This research collected and analyzed data on task performance of workers working indoors and outdoors with and without a cooling suit. The task performance was compared on the basis of heart rate, oxygen consumption, tympanic temperature, subjective responses, productivity, and error rates. Based on One-Way Analysis Of Variance (ANOVA) results, a significantly lower estimated working oxygen consumption was observed (p < .001) when the cooling suit was worn. The productivity was higher while workers wore the cooling suit as compared to no cooling suit (p = .011) whereas the error rates were significantly lower (p < .001). Also a significantly lower self-reported discomfort was observed in the neck and shoulders while working wearing the cooling suit (p = .004). This study concluded that wearing a cooling suit while working outdoors was associated with physiological benefits as well as improved task performance of the study participants.     

Invasion patterns inferred from cytochrome oxidase I sequences in three bryozoans, Bugula neritina, Watersipora subtorquata, and Watersipora arcuata

Nucleotide variation in cytochrome c oxidase subunit I (COI) was used to examine population structure in three invasive bryozoans: Bugula neritina (Linnaeus, 1758), Watersipora subtorquata (d’Orbigny, 1852), and W. arcuata (Banta, 1969). These species are found on ship hulls and have a short (≤2 days) larval phase. Samples were collected from 1998–2001 at multiple sites in Australia, and in Hong Kong, New Zealand, Hawaii, California, Curaçao, and England. B. neritina is known to include three cryptic species, including species Type S (Davidson and Haygood in Biol Bull 196:273–280, 1999) which occurs on the east and west coasts of the USA. One haplotype recorded previously in the USA, S1, was found to be widespread, occurring throughout Australia and in Hong Kong, Curaçao, Hawaii, and England. W. subtorquata, a Caribbean–Atlantic species which has invaded southern Australia, New Zealand, and California, had low nucleotide diversity in these areas (π=0.0016±0.0014), consisting of three haplotypes connected by one or two nucleotide mutations. W. arcuata, an Eastern-Pacific native, had comparatively high diversity (π=0.0221±0.0115) in introduced populations from Australia and Hawaii. In each species, identical haplotypes were identified on separate coastlines providing evidence of widespread, rather than genetically independent, introductions. The major contrast in nucleotide diversity suggests that different propagule-source models explain introductions.     

Energy in a woodland-livestock agroecosystem: Prince Edward Island,Canada, 1870–2010

Regional Environmental Change - This article presents historic energy profiles in order to understand the changing roles of three critical energy flows in eastern Canadian agroecosystems. The first...     

Evaluating outcomes of conservation with multidimensional indicators of well-being

Many conservation interventions are hypothesized to be beneficial for both the environment and people's well-being, but this has rarely been tested rigorously. We examined the effects of adoption or nonadoption of a conservation intervention on 3 dimensions of people's well-being (material, relational, and subjective) over time. We focused on a fisheries bycatch management initiative intended to reduce environmental externalities associated with resource extraction. We collected panel data from fishers (n = 250) in villages with (adopters and nonadopters) and without (control) the conservation intervention 3 times over 2 years. We found no evidence that adoption reduced any of the 3 dimensions of well-being in the local populations affected by the intervention. There were modest improvements in material (t = –1.58) and subjective livelihood well-being (p = 0.04) for adopters relative to nonadopters over time. The variations in well-being experiences (in terms of magnitude of change) among adopters, nonadopters, and controls across the different domains over time affirmed the dynamic and social nature of well-being.     

Adaptive introgression as a resource for management and genetic conservation in a changing climate

Current rates of climate change require organisms to respond through migration, phenotypic plasticity, or genetic changes via adaptation. We focused on questions regarding species’ and populations’ ability to respond to climate change through adaptation. Specifically, the role adaptive introgression, movement of genetic material from the genome of 1 species into the genome of another through repeated interbreeding, may play in increasing species’ ability to respond to a changing climate. Such interspecific gene flow may mediate extinction risk or consequences of limited adaptive potential that result from standing genetic variation and mutation alone, enabling a quicker demographic recovery in response to changing environments. Despite the near dismissal of the potential benefits of hybridization by conservation practitioners, we examined a number of case studies across different taxa that suggest gene flow between sympatric or parapatric sister species or within species that exhibit strong ecotypic differentiation may represent an underutilized management option to conserve evolutionary potential in a changing environment. This will be particularly true where advanced‐generation hybrids exhibit adaptive traits outside the parental phenotypic range, a phenomenon known as transgressive segregation. The ideas presented in this essay are meant to provoke discussion regarding how we maintain evolutionary potential, the conservation value of natural hybrid zones, and consideration of their important role in adaptation to climate.