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Measurement of humic-like substances in aerosols: A review Texte intégral
2013
Zheng, Guangjie | He, Kebin | Duan, Fengkui | Cheng, Yuan | Ma, Yongliang
Aerosol-phase humic-like substances (HULIS) have received increasingly attention due to their universal ambient presence, active participation in atmospheric chemistry and important environmental and health effects. In last decade, intensive field works have promoted development of quantification and analysis method, unearthed spatio-temporal variation, and proved evidence for source identification of HULIS. These important developments were summarized in this review to provide a global perspective of HULIS. The diverse operational HULIS definitions were gradually focused onto several versions. Although found globally in Europe, Asia, Australasia and North America, HULIS are far more typical in continental and near-ground aerosols. HULIS concentrations varied from <1 μg/m3 to >13 μg/m3, with their carbon fraction making up 9%–72% of water soluble organic carbon. Dominant HULIS source was suggested as secondary processes and biomass burning, with the detailed formation pathways suggested and verified in laboratory works.
Afficher plus [+] Moins [-]Phytotoxicity and oxidative stress effect of 1-octyl-3-methylimidazolium chloride ionic liquid on rice seedlings Texte intégral
2013
Liu, Huijun | Zhang, Shuxian | Hu, Xiaona | Chen, Caidong
The effects of the ionic liquid 1-octyl-3-methylimidazolium chloride ([OMIM]Cl) was studied in hydroponically grown rice seedlings. Observed effects included increased root length and weight at concentrations of 0.1 mg/L [OMIM]Cl, however, as concentrations increased a reversed response was observed where roots and stems grew shorter and the weight decreased. The inhibitory concentration 50 (IC50,5d) values for root length and stem length were 0.59 mg/L and 0.70 mg/L, respectively. The Hill reaction activity and root system activity in [OMIM]Cl-treated rice seedlings were observed to be lower than the controls, however, root membrane permeability increased. The antioxidant enzyme activity in roots decreased, while in leaves there was an initial stimulation followed by a decrease. Malondialdehyde (MDA) content was found to be greater in seedlings subjected to [OMIM]Cl treatment. The cellular structures, such as chloroplasts, mitochondria and rough endoplasmic reticulum in rice root and leaf cells were affected at concentrations of 0.6 mg/L [OMIM]Cl.
Afficher plus [+] Moins [-]Quantitative analysis on the urban flood mitigation effect by the extensive green roof system Texte intégral
2013
Lee, J.Y. | Moon, H.J. | Kim, T.I. | Kim, H.W. | Han, M.Y.
Extensive green-roof systems are expected to have a synergetic effect in mitigating urban runoff, decreasing temperature and supplying water to a building. Mitigation of runoff through rainwater retention requires the effective design of a green-roof catchment. This study identified how to improve building runoff mitigation through quantitative analysis of an extensive green-roof system. Quantitative analysis of green-roof runoff characteristics indicated that the extensive green roof has a high water-retaining capacity response to rainfall of less than 20 mm/h. As the rainfall intensity increased, the water-retaining capacity decreased. The catchment efficiency of an extensive green roof ranged from 0.44 to 0.52, indicating reduced runoff comparing with efficiency of 0.9 for a concrete roof. Therefore, extensive green roofs are an effective storm water best-management practice and the proposed parameters can be applied to an algorithm for rainwater-harvesting tank design.
Afficher plus [+] Moins [-]Estimation of the algal-available phosphorus pool in sediments of a large, shallow eutrophic lake (Taihu, China) using profiled SMT fractional analysis Texte intégral
2013
Zhu, Mengyuan | Zhu, Guangwei | Li, Wei | Zhang, Yunlin | Zhao, Linlin | Gu, Zhao
Because large, shallow lakes are heavily influenced by wind–wave disturbance, it is difficult to estimate internal phosphorus load using traditional methods. To estimate the potential contribution of phosphorus from sediment to overlying water in eutrophic Lake Taihu, phosphorus fractions of surface and deep layer sediments were quantified and analyzed for algal bloom potential using a Standard Measurements and Testing (SMT) sequential extraction method and incubation experiments. Phosphorus bound to Fe, Al and Mn oxides and hydroxides (Fe–P) and organic phosphorus (OP) were to be found bioactive. The difference in Fe–P and OP contents between surface and deep layers equates to the sediment pool of potentially algal-available phosphorus. This pool was estimated at 5168 tons for the entire lake and was closely related to pollution input and algal blooms. Profiled SMT fractionation analysis is thus a potentially useful tool for estimating internal phosphorus loading in large, shallow lakes.
Afficher plus [+] Moins [-]Increased frequency and severity of developmental deformities in rough-skinned newt (Taricha granulosa) embryos exposed to road deicing salts (NaCl & MgCl2) Texte intégral
2013
Hopkins, Gareth R. | French, Susannah S. | Brodie, Edmund D.
Road-side aquatic ecosystems in North America are annually polluted with millions of tons of road deicing salts, which threaten the survival of amphibians which live and breed in these habitats. While much is known of the effects of NaCl, little is known of the second most-commonly used deicer, MgCl2, which is now used exclusively in parts of the continent. Here we report that environmentally relevant concentrations of both NaCl and MgCl2 cause increased incidence of developmental deformities in rough-skinned newt hatchlings that developed embryonically in these salts. In addition, we provide some of the first quantification of severity of different deformities, and reveal that increased salt concentrations increase both deformity frequency and severity. Our work contributes to the growing body of literature that suggests salamanders and newts are particularly vulnerable to salt, and that the emerging pollutant, MgCl2 is comparable in its effects to the more traditionally-used NaCl.
Afficher plus [+] Moins [-]Can citizen science produce good science? Testing the OPAL Air Survey methodology, using lichens as indicators of nitrogenous pollution Texte intégral
2013
Tregidgo, Daniel J. | West, Sarah E. | Ashmore, M. R. (Mike R.)
Citizen science is having increasing influence on environmental monitoring as its advantages are becoming recognised. However methodologies are often simplified to make them accessible to citizen scientists. We tested whether a recent citizen science survey (the OPAL Air Survey) could detect trends in lichen community composition over transects away from roads. We hypothesised that the abundance of nitrophilic lichens would decrease with distance from the road, while that of nitrophobic lichens would increase. The hypothesised changes were detected along strong pollution gradients, but not where the road source was relatively weak, or background pollution relatively high. We conclude that the simplified OPAL methodology can detect large contrasts in nitrogenous pollution, but it may not be able to detect more subtle changes in pollution exposure. Similar studies are needed in conjunction with the ever-growing body of citizen science work to ensure that the limitations of these methods are fully understood.
Afficher plus [+] Moins [-]The effects of aluminum and nickel in nectar on the foraging behavior of bumblebees Texte intégral
2013
Meindl, George A. | Ashman, Tia-Lynn
Metals in soil are known to negatively affect the health of many groups of organisms, but it is unclear whether they can affect plant-pollinator interactions, and whether pollinators that visit plants growing on contaminated soils are at risk of ingesting potentially toxic resources. We address whether the presence of metals in nectar alters foraging behavior by bumblebees by manipulating nectar with one of two common soil contaminants (Al or Ni) in flowers of Impatiens capensis (Balsaminaceae). While the presence of Al in nectar did not influence foraging patterns by bumblebees, flowers containing Ni nectar solutions were visited for shorter time periods relative to controls, and discouraged bees from visiting nearby Ni-contaminated flowers. However, because bumblebees still visited these flowers, they likely ingested a potentially toxic resource. Our findings suggest that soil metals could cascade to negatively affect pollinators in metal contaminated environments.
Afficher plus [+] Moins [-]Biomonitoring study of an estuarine coastal ecosystem, the Sacca di Goro lagoon, using Ruditapes philippinarum (Mollusca: Bivalvia) Texte intégral
2013
Sacchi, Ângela | Mouneyrac, Catherine | Bolognesi, Claudia | Sciutto, Andrea | Roggieri, Paola | Fusi, Marco | Beone, Gian Maria | Capri, Ettore
Coastal lagoons are constantly subjected to releases of chemical pollutants, and so organisms may be exposed to such toxicants. This study investigated through a multivariate approach the physiological status of bivalve Ruditapes philippinarum, farmed in Sacca di Goro lagoon. Biomarkers at different levels of biological organization (catalase, superoxide dismutase, genotoxicity, reburrowing behavior) were evaluated at three sites exposed to different environmental conditions. A seasonal trend was observed, and micronucleus frequency was significantly lowest at the relatively pristine reference site. Enzymatic activity toward oxyradicals be quite efficient since variations in responsiveness were not consistent. However, behavioral impairment was observed in reburrowing rates. Sediment concentrations showed low PAH levels and high natural levels of trace metals Cr and Ni. DistLM statistical analysis revealed a non-significant relationship between selected biomarkers and xenobiotics. Therefore other potentially toxic compounds in admixture at low doses may be involved in driving differing spatial distribution of physiological impairment.
Afficher plus [+] Moins [-]Ultrastructural changes and Heat Shock Proteins 70 induced by atmospheric pollution are similar to the effects observed under in vitro heavy metals stress in Conocephalum conicum (Marchantiales – Bryophyta) Texte intégral
2013
Changes in ultrastructure and induction of Heat Shock Proteins 70 have been studied in Conocephalum conicum (Marchantiales) collected in different urban and country sites in Italy. These results were compared to the effects in vitro of exposition to different heavy metals for several days.At urban sites, cellular ultrastructure was modified, and heavy metals could be observed accumulating in cell walls. Simultaneously, a strong increment in Hsp70 was detected, compared with results observed on control specimens.When C. conicum was exposed to heavy metals in vitro, comparable effects as in polluted sites were observed: Cd and Pb accumulated mostly within parenchyma and, within cells, were absorbed to cell walls or concentrated in vacuoles. Moreover, severe alterations were observed in organelles. Concomitantly, a progressive accumulation of Hsp70 was detected following heavy metals exposition.These effects are discussed in order to describe the dose and time-dependent response to heavy metal stress in C. conicum.
Afficher plus [+] Moins [-]Mineralogy affects geoavailability, bioaccessibility and bioavailability of zinc Texte intégral
2013
We correlated mineralogical and particle characteristics of Zn-containing particles with Zn geoavailability, bioaccessibility, and bioavailability following gavage and intranasal (IN) administration in rats. We compared samples of Zn/Pb mine waste and five pulverized pure-phase Zn minerals (<38 μm). Particles were neutron-activated to produce radioactive 65Zn. We assessed geoavailability using sequential extractions and bioaccessibility using in vitro extraction tests simulating various pH and biological conditions. Zn in vivo bioavailability and in vitro bioaccessibility decreased as follows: mine waste > hydrozincite > hemimorphite > zincite ≈ smithsonite >> sphalerite. We found significant correlations among geoavailability, bioaccessibility and bioavailability. In particular, Zn bioavailability post-gavage and post-IN was significantly correlated with bioaccessibility in simulated phagolysosomal fluid and gastric fluid. These data indicate that solid phase speciation influences biological uptake of Zn and that in vitro tests can be used to predict Zn bioavailability in exposure assessment and effective remediation design.
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