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Associations between standardized school performance tests and mixtures of Pb, Zn, Cd, Ni, Mn, Cu, Cr, Co, and V in community soils of New Orleans
2012
Zahran, Sammy | Mielke, Howard W. | Weiler, Stephan | Hempel, Lynn | Berry, Kenneth J. | Gonzales, Christopher R.
In New Orleans a strong inverse association was previously identified between community soil lead and 4th grade school performance. This study extends the association to zinc, cadmium, nickel, manganese, copper, chromium, cobalt, and vanadium in community soil and their comparative effects on 4th grade school performance. Adjusting for poverty, food security, racial composition, and teacher-student ratios, regression results show that soil metals variously reduce and compress student scores. Soil metals account for 22%–24% while food insecurity accounts for 29%–37% of variation in school performance. The impact on grade point averages were Ni > Co > Mn > Cu ∼Cr ∼ Cd > Zn > Pb, but metals are mixtures in soils. The quantities of soil metal mixtures vary widely across the city with the largest totals in the inner city and smallest totals in the outer city. School grade point averages are lowest where the soil metal mixtures and food insecurity are highest.
Afficher plus [+] Moins [-]Polychlorinated naphthalenes (PCNs) in the surface soils of the Pearl River Delta, South China: Distribution, sources, and air-soil exchange
2012
Wang, Yan | Cheng, Zhineng | Li, Jun | Luo, Chunling | Xu, Yue | Li, Qilu | Liu, Xiang | Zhang, Gan
Polychlorinated naphthalenes (PCNs) are now under review by the Stockholm Convention as a candidate for POPs for their persistence, toxicity, bioaccumulation, and long-range atmospheric transport. Data regarding PCN levels and their environmental fate are sparse in China. The PCN concentration and distribution in soils of the Pearl River Delta were reported, and the average total concentration was 59.9 ± 86.7 pg/g. Tri-CNs was the dominant homologue group, and CN 24 was the most abundant congener. A gradient of PCN levels between more and less developed areas was observed. Based on fugacity fraction results, CN 51 is proposed as a possible source marker for specific combustion emissions. Air-soil exchange of PCNs was estimated by calculating the soil and air fugacity. Fugacity fraction values indicated that tri- to penta-CNs were closer to equilibrium in winter and toward net volatilization in summer, while hexa-CNs experienced net air-to-soil transfer in both seasons.
Afficher plus [+] Moins [-]The effect of EDTA, NTA and picolinic acid on Th(IV) mobility in a ternary system with natural sand
2012
Reinoso-Maset, Estela | Worsfold, Paul J. | Keith-Roach, M. J. (Miranda J.)
Organic complexing agents, such as ethylenediaminetetraacetic acid (EDTA), nitrilotriacetic acid (NTA) and picolinic acid, have been widely used at nuclear sites and are therefore found as common co-contaminants in radioactive contaminated land. This study has explored the mechanisms by which these three complexing agents affect the sorption of Th(IV) to pure silica and a natural sand. EDTA, NTA and, to a lesser extent, picolinic acid decreased the sorption of Th to silica, demonstrating the formation and solubility of Th complexes. However, Th sorption to sand was kinetically controlled and complexation enhanced the rate of Th sorption. EDTA and NTA did not sorb significantly to the sand, and metal desorption indicated that the mechanism involved exchange with sand-associated metals. At equilibrium, however, Th sorption was not affected by the presence of the ligands, and modelling suggested that the interaction between Th and the surface binding sites controlled Th sorption thermodynamically.
Afficher plus [+] Moins [-]Anthropogenic and natural sources of acidity and metals and their influence on the structure of stream food webs
2012
Hogsden, Kristy L. | Harding, Jon S.
We compared food web structure in 20 streams with either anthropogenic or natural sources of acidity and metals or circumneutral water chemistry in New Zealand. Community and diet analysis indicated that mining streams receiving anthropogenic inputs of acidic and metal-rich drainage had much simpler food webs (fewer species, shorter food chains, less links) than those in naturally acidic, naturally high metal, and circumneutral streams. Food webs of naturally high metal streams were structurally similar to those in mining streams, lacking fish predators and having few species. Whereas, webs in naturally acidic streams differed very little from those in circumneutral streams due to strong similarities in community composition and diets of secondary and top consumers. The combined negative effects of acidity and metals on stream food webs are clear. However, elevated metal concentrations, regardless of source, appear to play a more important role than acidity in driving food web structure.
Afficher plus [+] Moins [-]Distributions and impact factors of antimony in topsoils and moss in Ny-Ålesund, Arctic
2012
Jia, Nan | Sun, Liguang | He, Xin | You, Kehua | Zhou, Xin | Long, Nanye
The distribution of antimony (Sb) in topsoil and moss (Dicranum angustum) in disturbed and undisturbed areas, as well as coal and gangue, in Ny-Ålesund, Arctic was examined. Results show that the weathering of coal bed could not contribute to the increase of Sb concentrations in topsoil and moss in the study area. The distribution of Sb is partially associated with traffic and historical mining activities. The occurrence of the maximum Sb concentration is due to the contribution of human activities. In addition, the decrease of Sb content in topsoil near the coastline may be caused by the washing of seawater. Compared with topsoils, moss could be a useful tool for monitoring Sb in both highly and lightly polluted areas.
Afficher plus [+] Moins [-]Batch versus continuous feeding strategies for pharmaceutical removal by subsurface flow constructed wetland
2012
Zhang, Dong Qing | Gersberg, Richard M. | Zhu, Junfei | Hua, Tao | Jinadasa, K.B.S.N. | Tan, Soon Keat
This study evaluated the effect of continuous and batch feeding on the removal of 8 pharmaceuticals (carbamazepine, naproxen, diclofenac, ibuprofen, caffeine, salicylic acid, ketoprofen and clofibric acid) from synthetic wastewater in mesocosm-scale constructed wetlands (CWs). Both loading modes were operated at hydraulic application rates of 5.6 cm day⁻¹ and 2.8 cm day⁻¹. Except for carbamazepine, clofibric acid and naproxen, removal in CWs was significantly (p < 0.05) enhanced under the batch versus continuous mode. For all compounds tested except naproxen, values for first-order decay constants (k) for drain and fill operation were higher than that for the continuous mode of operation. Correlation between the distribution coefficient (log Dₒw) and removal efficiencies of pharmaceutical compounds in the CWs, showed that pharmaceutical removal efficiency was significantly (p < 0.1) and inversely correlated with log Dₒw value, but not with log Kₒw value.
Afficher plus [+] Moins [-]Growth, development and incidence of deformities in amphibian larvae exposed as embryos to naphthenic acid concentrations detected in the Canadian oil sands region
2012
Melvin, Steven D. | Trudeau, Vance L.
Naphthenic acids (NA) have been identified as harmful environmental contaminants that influence survival, growth and development of wildlife. Amphibian larvae are particularly susceptible to waterborne contaminants, but little information exists regarding exposure of amphibian embryos or tadpoles to NA. Our results demonstrate that embryos of Lithobates pipiens and Silurana tropicalis exposed to 2–4 mg/l of a commercial NA blend suffer significant reductions (32% and 25%, respectively) in growth and development upon hatching. Increased incidences of deformities were observed in exposed individuals of both species, but were only significant in L. pipiens. Embryos suffered 100% mortality following exposure to 6 mg/l NAs, and narcosis at lower concentrations. LC50 estimates were 4.10 mg/l for 72-h exposure in L. pipiens and 4.13, 3.51, and 2.95 mg/l for 24-, 48-, and 72-h exposure in S. tropicalis. These data suggest that exposure to NAs at environmentally realized concentrations may negatively affect tadpole populations.
Afficher plus [+] Moins [-]High nitrogen and elevated [CO₂] effects on the growth, defense and photosynthetic performance of two eucalypt species
2012
Novriyanti, Eka | Watanabe, Makoto | Kitao, Mitsutoshi | Utsugi, Hajime | Uemura, Akira | Koike, Takayoshi
Atmospheric nitrogen deposition and [CO₂] are increasing and represent environmental problems. Planting fast-growing species is prospering to moderate these environmental impacts by fixing CO₂. Therefore, we examined the responses of growth, photosynthesis, and defense chemical in leaves of Eucalyptus urophylla (U) and the hybrid of E. deglupta × E. camadulensis (H) to different CO₂ and nitrogen levels. High nitrogen load significantly increased plant growth, leaf N, net photosynthetic rate (Agᵣₒwₜₕ), and photosynthetic water use efficiency (WUE). High CO₂ significantly increased Agᵣₒwₜₕ, photosynthetic nitrogen use efficiency (PNUE) and WUE. Secondary metabolite (SM, i.e. total phenolics and condensed tannin) was specifically altered; as SM of U increased by high N load but not by elevated [CO₂], and vice versa for SM of H.
Afficher plus [+] Moins [-]Temporal and spatial trends of perfluoroalkyl substances in liver of roe deer (Capreolus capreolus)
2012
Falk, Sandy | Brunn, Hubertus | Schröter-Kermani, Christa | Failing, Klaus | Georgii, Sebastian | Tarricone, Kathrin | Stahl, Thorsten
For more than 50 years perfluoroalkyl substances (PFASs) have found worldwide industrial and household uses. Some PFASs are presumed to be persistent and bioaccumulative. Roe deer (Capreolus capreolus) are thought to be a suitable bioindicator for the accumulation of organic xenobiotics. Due to the ubiquitous nature of PFASs in the environment a retrospective study on temporal trends was carried out. A total of 110 deer liver pools collected from 1989 to 2010 in Germany were analyzed for their levels of PFASs. The highest concentrations were measured for perfluorooctane sulfonate (PFOS) (median 6.3 μg/kg). Perfluorooctanoic acid (PFOA), perfluorononanoic acid (PFNA) and perfluorodecanoic acid (PFDA) were detected with median concentrations of 0.5 μg/kg, 1.2 μg/kg and 0.3 μg/kg, respectively, while concentrations of the other PFASs were below the limit of quantification. PFOS concentrations decreased significantly (rₛ = −0.741; p = <0.0001) from 9.2 μg/kg in 2000 to 1.8 μg/kg in 2010.
Afficher plus [+] Moins [-]Reduced soil water availability did not protect two competing grassland species from the negative effects of increasing background ozone
2012
Wagg, Serena | Mills, Gina | Hayes, Felicity | Wilkinson, Sally | Cooper, David | Davies, William J.
Two common (semi-) natural temperate grassland species, Dactylis glomerata and Ranunculus acris, were grown in competition and exposed to two watering regimes: well-watered (WW, 20–40% v/v) and reduced-watered (RW, 7.5–20% v/v) in combination with eight ozone treatments ranging from pre-industrial to predicted 2100 background levels. For both species there was a significant increase in leaf damage with increasing background ozone concentration. RW had no protective effect against increasing levels of ozone-induced senescence/injury. In high ozone, based on measurements of stomatal conductance, we propose that ozone influx into the leaves was not prevented in the RW treatment, in D. glomerata because stomata were a) more widely open than those in less polluted plants and b) were less responsive to drought. Total seasonal above ground biomass was not significantly altered by increased ozone; however, ozone significantly reduced root biomass in both species to differing amounts depending on watering regime.
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