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961.
Juan José Rosso Nahuel F. Schenone Alejo Pérez Carrera Alicia Fernández Cirelli 《Environmental geochemistry and health》2013,35(2):201-214
Arsenic (As) may occur in surface freshwater ecosystems as a consequence of both natural contamination and anthropogenic activities. In this paper, As concentrations in muscle samples of 10 fish species, sediments and surface water from three naturally contaminated rivers in a central region of Argentina are reported. The study area is one of the largest regions in the world with high As concentrations in groundwater. However, information of As in freshwater ecosystems and associated biota is scarce. An extensive spatial variability of As concentrations in water and sediments of sampled ecosystems was observed. Geochemical indices indicated that sediments ranged from mostly unpolluted to strongly polluted. The concentration of As in sediments averaged 6.58 μg/g ranging from 0.23 to 59.53 μg/g. Arsenic in sediments barely followed (r = 0.361; p = 0.118) the level of contamination of water. All rivers showed high concentrations of As in surface waters, ranging from 55 to 195 μg/L. The average concentration of As in fish was 1.76 μg/g. The level of contamination with As differed significantly between species. Moreover, the level of bioaccumulation of As in fish species related to the concentration of As in water and sediments also differed between species. Whilst some fish species seemed to be able to regulate the uptake of this metalloid, the concentration of As in the large catfish Rhamdia quelen mostly followed the concentration of As in abiotic compartments. The erratic pattern of As concentrations in fish and sediments regardless of the invariable high levels in surface waters suggests the existence of complex biogeochemical processes behind the distribution patterns of As in these naturally contaminated ecosystems. 相似文献
962.
Stephanie Mesías Monsalve Leonardo Martínez Karla Yohannessen Vásquez Sergio Alvarado Orellana José Klarián Vergara Miguel Martín Mateo Rogelio Costilla Salazar Mauricio Fuentes Alburquenque Dante D. Cáceres Lillo 《Environmental geochemistry and health》2018,40(3):1077-1091
Air quality in schools is an important public health issue because children spend a considerable part of their daily life in classrooms. Particulate size and chemical composition has been associated with negative health effects. We studied levels of trace element concentrations in fine particulate matter (PM2.5) in indoor versus outdoor school settings from six schools in Chañaral, a coastal city with a beach severely polluted with mine tailings. Concentrations of trace elements were measured on two consecutive days during the summer and winter of 2012 and 2013 and determined using X-ray fluorescence. Source apportionment and element enrichment were measured using principal components analysis and enrichment factors. Trace elements were higher in indoor school spaces, especially in classrooms compared with outdoor environments. The most abundant elements were Na, Cl, S, Ca, Fe, K, Mn, Ti, and Si, associated with earth’s crust. Conversely, an extremely high enrichment factor was determined for Cu, Zn, Ni and Cr; heavy metals associated with systemic and carcinogenic risk effects, whose probably origin sources are industrial and mining activities. These results suggest that the main source of trace elements in PM2.5 from these school microenvironments is a mixture of dust contaminated with mine tailings and marine aerosols. Policymakers should prioritize environmental management changes to minimize further environmental damage and its direct impact on the health of children exposed. 相似文献
963.
Mobilization of aluminum by the acid percolates within unsaturated zone of sandstones 总被引:1,自引:0,他引:1
Tomáš Navrátil Zuzana Vařilová Jan Rohovec 《Environmental monitoring and assessment》2013,185(9):7115-7131
The area of the Black Triangle has been exposed to extreme levels of acid deposition in the twentieth century. The chemical weathering of sandstones found within the Black Triangle became well-known phenomenon. Infiltration of acid rain solutions into the sandstone represents the main input of salt components into the sandstone. The infiltrated solutions–sandstone percolates–react with sandstone matrix and previously deposited materials such as salt efflorescence. Acidic sandstone percolates pH?3.2–4.8 found at ten sites within the National Park Bohemian Switzerland contained high Al-tot (0.8–10 mg?L?1) concentrations and high concentrations of anions SO4 (5–66 mg?L?1) and NO3 (2–42 mg?L?1). A high proportion (50–98 %) of Al-tot concentration in acid percolates was represented by toxic reactive Aln+. Chemical equilibrium modeling indicated as the most abundant Al species Al3+, AlSO4 +, and AlF2+. The remaining 2–50 % of Al-tot concentration was present in the form of complexes with dissolved organic matter Al-org. Mobilization and transport of Al from the upper zones of sandstone causes chemical weathering and sandstone structure deterioration. The most acidic percolates contained the highest concentrations of dissolved organic material (estimated up to 42 mg?L?1) suggesting the contribution of vegetation on sandstone weathering processes. Very low concentrations of Al-tot in springs at BSNP suggest that Al mobilized in unsaturated zone is transported deeper into the sandstone. This process of mobilization could represent a threat for the water quality small-perched aquifers. 相似文献
964.
Cleisson Fábio A. Peralta Victor Bunduki José Píndaro P. Plese Eberval Gadelha Figueiredo Javier Miguelez Marcelo Zugaib 《黑龙江环境通报》2003,23(4):311-314
This study presents 30 cases of fetal isolated spina bifida aperta (SBA) to identify prenatal ultrasound findings that could predict the prognosis. Comparisons between surviving patients who had normal (group 1) and abnormal (group 2) post-natal neurological outcomes were made for three different prenatal signs, that is, site of vertebral lesion, presence and degree of ventriculomegaly and presence of talipes. The site of the lesion was the most significant outcome predictor, as high spinal dysraphisms were observed in 2 patients (2/7–28.6%) in group 1 and in 15 patients (15/19–79.0%) in group 2 (p = 0.03). The presence of fetal ventriculomegaly was associated with impaired post-natal neurological development, as it occurred in 4 patients (4/7–57.1%) in group 1 and in 18 patients (18/19–94.7%) in group 2 (p = 0.04). The presence of talipes did not significantly differ between the two groups. Patients with abnormal intellectual outcome (8/26–30.8%) had significantly greater (p = 0.018) lateral ventricle/hemisphere ratios (mean = 0.74, standard deviation = 0.13) than those with normal intellectual development (mean = 0.54, standard deviation = 0.18). Mean post-natal follow-up was at 23 months (standard deviation = 15 months). Copyright © 2003 John Wiley & Sons, Ltd. 相似文献
965.
Gergely Forgács Saeid Alinezh Amir Mirabdollah Elisabeth Feuk-Lagerstedt Ilona Sárvári Horváth 《环境科学学报(英文版)》2011,23(10):1747-1753
A two-stage system was developed which combines the biological degradation of keratin-rich waste with the production of biogas. Chicken feather waste was treated biologically with a recombinant Bacillus megaterium strain showing keratinase activity prior to biogas production. Chopped, autoclaved chicken feathers (4%, W/V) were completely degraded, resulting in a yellowish fermentation broth with a level of 0.51 mg/mL soluble proteins after 8 days of cultivation of the recombinant strain. During the subsequent anaerobic batch digestion experiments, methane production of 0.35 Nm3/kg dry feathers (i.e., 0.4 Nm3/kg volatile solids of feathers), corresponding to 80% of the theoretical value on proteins, was achieved from the feather hydrolyzates, independently of the pre-hydrolysis time period of 1, 2 or 8 days. Cultivation with a native keratinase producing strain, Bacillus licheniformis resulted in only 0.25 mg/mL soluble proteins in the feather hydrolyzate, which then was digested achieving a maximum accumulated methane production of 0.31 Nm3/kg dry feathers. Feather hydrolyzates treated with the wild type B. megaterium produced 0.21 Nm3 CH4/kg dry feathers as maximum yield. 相似文献
966.
967.
Talavera Mendoza O Armienta Hernández MA Abundis JG Mundo NF 《Environmental geochemistry and health》2006,28(3):243-255
Leachates from the El Fraile tailings impoundment (Taxco, Mexico) were monitored every 2 months from October 2001 to August 2002 to assess the geochemical characteristics. These leachates are of interest because they are sometimes used as alternative sources of domestic water. Alternatively, they drain into the Cacalotenango creek and may represent a major source of metal contamination of surface water and sediments. Most El Fraile leachates show characteristics of Ca–SO4, (Ca+Mg)–SO4, Mg–SO4 and Ca–(SO4+HCO3) water types and are near-neutral (pH=6.3–7.7). Some acid leachates are generated by the interaction of meteoric water with tailings during rainfall events (pH=2.4–2.5). These contain variable levels of SO4
2− (280–29,500 mg l−1) and As (<0.01–12.0 mg l−1) as well as Fe (0.025–2352 mg l−1), Mn (0.1–732 mg l−1), Zn (<0.025–1465 mg l−1) and Pb (<0.01–0.351 mg l−1). Most samples show the highest metal enrichment during the dry seasons. Leachates used as domestic water typically exceed the Mexican Drinking Water Guidelines for sulfate, hardness, Fe, Mn, Pb and As, while acidic leachates exceed the Mexican Guidelines for Industrial Discharge Waters for pH, Cu, Cd and As. Speciation shows that in near-neutral solutions, metals exist mainly as free ions, sulfates and bicarbonates, while in acidic leachates they are present as sulfates and free ions. Arsenic appears as As(V) in all samples. Thermodynamic and mineralogical evidence indicates that precipitation of Fe oxides and oxyhydroxides, clay minerals and jarosite as well as sorption by these minerals are the main processes controlling leachate chemistry. These processes occur mainly after neutralization by interaction with bedrock and equilibration with atmospheric oxygen. 相似文献
968.
D. Jasso de Rodríguez J. L. Angulo-Sánchez R. Rodríguez-García 《Journal of Polymers and the Environment》2006,14(1):37-47
Guayule is a shrub native to Mexico growing in semiarid lands, that may be incorporated into the semiarid region production
system as a complement for annual crops. The possibility to develop this natural resource as a sustainable industrial source
of natural rubber, may improve the socio-economical level of people living at the guayule region and favor the agricultural
development near the US-Mexico border. Despite the existence of natural stands in Mexico with guayule plants of different
rubber content, a program envisaging selection of plants with high rubber synthesis potential joined to agronomic management
practices are required. This could achieve the rubber yield needed to guarantee a constant supply of raw material for an industrial
processing plant. This paper reviews R&D work carried out in Mexico for the last 25 years, including genetic aspects and evaluation
of guayule response to environmental and agronomic factors. Relevant results showed plants with up to 21% rubber content and
the existence of diploid plants, which could facilitate future plant breeding programs. 相似文献
969.
Josef Hrnčiřík Jiří Pšeja Jan Kupec Světlana Bernkopfová 《Journal of Polymers and the Environment》2010,18(2):98-103
This work focused on anaerobic biodegradation of blends composed of glycerol-plasticized polyvinyl alcohol (PVA) and biopolymer
(starch, gellan, xanthan) in an aqueous environment, after inoculation with digested activated sludge from a municipal wastewater
treatment plant. Glycerol degradability is comparable to degradability of used modifying agents. Modifying agents added in
the 20–40 wt% range proportionally increased biodegradation degree (Dt) calculated from balance of transformed carbon in the system. Biodegradation degree of polysaccharides and glycerol attained
95% and over. For PVA it was only 6.5% (in breakdown times up to 500 h). Content of polysaccharides favorably affects biodegradation
degree of polyvinyl alcohol blends, but at the expense of reduced mechanical properties of resultant products. 相似文献
970.
Kohler J Tortosa G Cegarra J Caravaca F Roldán A 《Waste management (New York, N.Y.)》2008,28(8):1423-1431
Water-soluble extracts from compost may represent an alternative nutrient and organic matter source for crop production under drip irrigation. Dissolved organic matter (DOM), extracted from composted "alperujo", the main by-product from the Spanish olive oil industry, was applied to soil alone or in combination with either Glomus intraradices Schenck and Smith or a mixture of G. intraradices, Glomus deserticola (Trappe, Bloss. and Menge) and Glomus mosseae (Nicol and Gerd.) Gerd. and Trappe. Response measurements included mycorrhizal colonisation, nutrient uptake and growth of Medicago sativa and microbiological and physical properties in the rhizosphere. Dissolved organic matter was added to soil at concentrations of 0, 50, 100 or 300mgCkg(-1) substrate. During the four months of the experiment, the plants were harvested three times. Both mycorrhizal inoculation treatments significantly increased soil aggregate stability. Only the mycorrhizal inoculations increased microbial biomass C and protease and phosphatase activities and decreased water-soluble C, particularly the mixture of arbuscular mycorrhizal fungi. At the third harvest, the greatest increase in growth of M. sativa was observed in the inoculated plants with shoot biomass being 38% greater than for plants grown in the soil amended with the highest dose of DOM and 57% greater than for control plants. The addition of DOM was not sufficient to restore soil structure and microbial activity and did not affect the mycorrhizal development of introduced populations of arbuscular mycorrhizal fungi, but, depending on the dose, its fertiliser efficiency for improving plant growth was apparent. 相似文献