Refine search
Results 331-340 of 3,240
Effects of cyanobacterial extracellular polymeric substances on the stability of ZnO nanoparticles in eutrophic shallow lakes Full text
2015
Xu, Huacheng | Jiang, Helong
Extracellular polymeric substances (EPS) from bloom-forming cyanobacteria exist ubiquitously in eutrophic waters, while their effects on the aggregation/stabilization of nanoparticles remain unknown. In this study, the stability of ZnO nanoparticles (ZNPs) upon adsorption of cyanobacterial EPS was investigated by using two dimensional ATR-FTIR correlation spectroscopy, XPS and DLVO theory. Results showed that the adsorption process followed the Langmuir isotherm and pseudo-second-order kinetics both for the total organic contents as well as the individual parallel factor-derived components. The physicochemical and spectroscopic techniques revealed the mechanism of both electrostatic attraction and surface complexation in EPS adsorption. Further analysis showed increased absorbance and turbidity of ZNPs solutions with EPS addition, demonstrating the enhanced colloidal stability. The DLVO theory explained that the increased energy barriers and values of second energy maximum were responsible for the stability enhancement. This study facilitates a deeper insight into the environmental behavior of nanoparticles in eutrophic algae-rich waters.
Show more [+] Less [-]Surface–rain interactions: Differences in copper runoff for copper sheet of different inclination, orientation, and atmospheric exposure conditions Full text
2015
Hedberg, Yolanda S. | Goidanich, Sara | Herting, Gunilla | Odnevall Wallinder, Inger
Predictions of the diffuse dispersion of metals from outdoor constructions such as roofs and facades are necessary for environmental risk assessment and management. An existing predictive model has been compared with measured data of copper runoff from copper sheets exposed at four different inclinations facing four orientations at two different urban sites (Stockholm, Sweden, and Milan, Italy) during a 4-year period. Its applicability has also been investigated for copper sheet exposed at two marine sites (Cadiz, Spain, for 5 years, and Brest, France, for 9 years). Generally the model can be used for all given conditions. However, vertical surfaces should be considered as surfaces inclined 60–80° due to wind-driven effects. The most important parameters that influence copper runoff, and not already included in the model, are the wind and rain characteristics that influence the actual rainfall volume impinging the surface of interest.
Show more [+] Less [-]Particulate matter modifies the magnitude and time course of the non-linear temperature-mortality association Full text
2015
Li, Li | Yang, Jun | Guo, Cui | Chen, Ping-Yan | Ou, Chun-Quan | Guo, Yuming
It remains uncertain whether air pollution modifies the magnitude and time course of the temperature-mortality association. We applied a distributed lag non-linear model (DLNM) combined with non-linear interaction terms to assess the modifying effects of particulate matter with an aerodynamic diameter of 10 μm or less (PM10) on the association between mean temperature and mortality in Guangzhou, China. We found that both cold and hot effects increased with the quartiles of PM10. The elderly were more vulnerable to cold and hot effects. Men suffered more from cold-related mortality than women, with the gender difference enlarging with the quartiles of PM10. We identified statistically significant interaction effects between PM10 and mean temperature on mortality (except for respiratory mortality). Cold and hot effects basically appeared acutely on highly polluted days, while effects were delayed on lowly polluted days. The findings indicate the importance of reducing PM10 emission on extremely temperature days.
Show more [+] Less [-]Distribution of mercury in archived fur from little brown bats across Atlantic Canada Full text
2015
Little, Megan E. | Burgess, Neil M. | Broders, Hugh G. | Campbell, Linda M.
Total mercury (Hg) concentrations were measured in archived fur from adult female little brown bats sampled at maternity roosts across Atlantic Canada. Mercury concentrations varied significantly among regions and roosts. Bats from Nova Scotia and Newfoundland had the highest median Hg concentrations (9.67 μg/g and 9.51 μg/g) among regions, and individuals from Kejimkujik National Park had the highest Hg (median: 28.38 μg/g) among roosts. Over one third of individuals sampled had fur Hg concentrations exceeding thresholds associated with neurochemical responses. Within-roost examinations of stable carbon and nitrogen isotopes in fur showed inconsistent associations with Hg concentrations. Therefore, the hypothesis that within-roost variation in Hg is driven by variation in diet is not supported by this data, and it is recommended that key prey items be included in future mercury bioaccumulation studies for bats. The elevated mercury fur concentrations for bats from southern Nova Scotia remains an anomaly of concern even when placed in the larger context of Atlantic Canada.
Show more [+] Less [-]Coupling spectroscopic and chromatographic techniques for evaluation of the depositional history of hydrocarbons in a subtropical estuary Full text
2015
Martins, César C. | Doumer, Marta E. | Gallice, Wellington C. | Dauner, Ana Lúcia L. | Cabral, Ana Caroline | Cardoso, Fernanda D. | Dolci, Natiely N. | Camargo, Luana M. | Ferreira, Paulo A.L. | Figueira, Rubens C.L. | Mangrich, Antonio S.
Spectroscopic and chromatographic techniques can be used together to evaluate hydrocarbon inputs to coastal environments such as the Paranaguá estuarine system (PES), located in the SW Atlantic, Brazil. Historical inputs of aliphatic hydrocarbons (AHs) and polycyclic aromatic hydrocarbons (PAHs) were analyzed using two sediment cores from the PES. The AHs were related to the presence of biogenic organic matter and degraded oil residues. The PAHs were associated with mixed sources. The highest hydrocarbon concentrations were related to oil spills, while relatively low levels could be attributed to the decrease in oil usage during the global oil crisis. The results of electron paramagnetic resonance were in agreement with the absolute AHs and PAHs concentrations measured by chromatographic techniques, while near-infrared spectroscopy results were consistent with unresolved complex mixture (UCM)/total n-alkanes ratios. These findings suggest that the use of a combination of techniques can increase the accuracy of assessment of contamination in sediments.
Show more [+] Less [-]Organobromine compound profiling in human adipose: Assessment of sources of bromophenol Full text
2015
Gao, Shixiong | Wan, Yi | Zheng, Guomao | Luo, Kai | Kannan, Kurunthachalam | Giesy, John P. | Lam, Michael H.W. | Hu, Jianying
Bromophenols (BRPs) have been widely detected in human tissues, however, relative proportions from natural products and/or anthropogenic flame retardants are not clear. 21 polybrominated diphenyl ethers (PBDEs), 15 MeO/OH-PBDEs, and 10 BRPs were simultaneously quantified in adipose collected from people from New York City, USA. An in vitro assay utilizing human liver microsomes was performed for detected predominant organobromine. High concentrations of 2,4,6-triBRP and PBDEs were observed, and extremely low concentrations of naturally occurring MeO/OH-PBDEs were detected. Similar biotransformatioin rates of BRPs and MeO/OH-PBDEs indicated that the relative high concentration of 2,4,6-triBRP in humans was not of natural origin. Significant correlation observed between concentrations of 2,4,6-triBRP and BDE-209 suggested that the two chemicals may share a common source. Both 2,4,6-triBRP and BDE-209 were detected in commercial ABS resins, suggesting that plastic products made from ABS resins could be potential sources of co-exposure of the two compounds for humans.
Show more [+] Less [-]Human exposure to mercury in a compact fluorescent lamp manufacturing area: By food (rice and fish) consumption and occupational exposure Full text
2015
Liang, Peng | Feng, Xinbin | Zhang, Chan | Zhang, Jin | Cao, Yucheng | You, Qiongzhi | Leung, Anna Oi Wah | Wong, Ming-Hung | Wu, Sheng-Chun
To investigate human Hg exposure by food consumption and occupation exposure in a compact fluorescent lamp (CFL) manufacturing area, human hair and rice samples were collected from Gaohong town, Zhejiang Province, China. The mean values of total mercury (THg) and methylmercury (MeHg) concentrations in local cultivated rice samples were significantly higher than in commercial rice samples which indicated that CFL manufacturing activities resulted in Hg accumulation in local rice samples. For all of the study participants, significantly higher THg concentrations in human hair were observed in CFL workers compared with other residents. In comparison, MeHg concentrations in human hair of residents whose diet consisted of local cultivated rice were significantly higher than those who consumed commercial rice. These results demonstrated that CFL manufacturing activities resulted in THg accumulation in the hair of CFL workers. However, MeHg in hair were mainly affected by the sources of rice of the residents.
Show more [+] Less [-]Assessment and mitigation of the environmental burdens to air from land applied food-based digestate Full text
2015
Tiwary, A. | Williams, I.D. | Pant, D.C. | Kishore, V.V.N.
Anaerobic digestion (AD) of putrescible urban waste for energy recovery has seen rapid growth over recent years. In order to ascertain its systems scale sustainability, however, determination of the environmental fate of the large volume of digestate generated during the process is indispensable. This paper evaluates the environmental burdens to air associated with land applied food-based digestate in terms of primary pollutants (ammonia, nitrogen dioxide) and greenhouse gases (methane and nitrous oxide). The assessments have been made in two stages – first, the emissions from surface application of food-based digestate are quantified for the business as usual (BAU). In the next step, environmental burden minimisation potentials for the following three mitigation measures are estimated – mixed waste digestate (MWD), soil-incorporated digestate (SID), and post-methanated digestate (PMD). Overall, the mitigation scenarios demonstrated considerable NH3, CH4 and N2O burden minimisation potentials, with positive implications for both climate change and urban pollution.
Show more [+] Less [-]Effects of landscape heterogeneity on the elevated trace metal concentrations in agricultural soils at multiple scales in the Pearl River Delta, South China Full text
2015
Li, Cheng | Li, Fangbai | Wu, Zhifeng | Cheng, Jiong
Based on multiple geo-accumulation indices and correlation and partial redundancy analyses, we examined the spatial patterns of agricultural soil contaminations for As, Pb, Cd, Cr, and Ni in the Pearl River Delta, South China and their relations with landscape heterogeneity at small, medium and large spatial scales. We found that the concentrations of trace elements were slightly elevated, and most trace metals had a geogenic origin. Landscape variables explained 21–53% of the variation of elevated trace metal concentrations with an increasing explanatory power from the small to the large scale. The three variable groups representing parent materials, distance density characteristics and land use had different contributions to the elevated trace metals among scales. Both the distance density variables and land use pattern had a stronger influences on trace metal concentrations at a small scale than at a larger scale, while the parent materials was important at all the scales.
Show more [+] Less [-]Joint effects of pesticides and ultraviolet-B radiation on amphibian larvae Full text
2015
Yu, Shuangying | Wages, Mike | Willming, Morgan | Cobb, George P. | Maul, Jonathan D.
A combination of multiple stressors may be linked to global amphibian declines. Of these, pesticides and UVB radiation co-exposures were examined on the African clawed frog (Xenopus laevis) to provide information that may be useful for amphibian conservation. The independent action model and inferential statistics were used to examine interactions between pesticides (malathion, endosulfan, α-cypermethrin, or chlorothalonil) and environmentally relevant UVB exposures. UVB radiation alone caused 35–68% mortality and nearly 100% of malformations. Pesticides and UVB had additive effects on larval mortality; however, several non-additive effects (antagonistic and synergistic interactions) were observed for total body length. Insecticides mainly affected axial development, whereas UVB radiation caused high incidence of edema, gut malformations, and abnormal tail tips. These results suggest that sublethal developmental endpoints were more sensitive for detecting joint effects. This work has implications for amphibian risk assessments for ecosystems where pesticides and high UVB radiation may co-occur.
Show more [+] Less [-]