长江上游水土流失成因及治理模式研究--以重庆市城口县为例

水土保持工作是一项直接关系三峡工程和“南水北调”工程的重要工作,也是西部生态环境建设的重要内容之一。以“长治”工程重点县——城口县为例,研究其水土流失成因及治理模式。该县位于重庆市最北端,既是“长治”工程重点县,也是“南水北调”工程中线引水方案丹江口水库上游水土保持工作重点县。该县水土流失比较严重,流失面积高达1 728.67 km\+2,占全县土地总面积的52.61%。造成水土流失的主要原因既有自然因素,又有人为因素,但其资源相当丰富,为水土流失治理模式提供了较好的基础条件。在分析其水土流失成因基础上,结合该县的资源优势和实际情况,提出其水土流失治理的模式和途径,以期进一步推进该县生态环境建设、加强水土保持工作,为长江上游贫困山区县的水土保持工作探索比较合适的模式和途径。     

Bayesian analysis of Jolly-Seber type models

We propose the use of finite mixtures of continuous distributions in modelling the process by which new individuals, that arrive in groups, become part of a wildlife population. We demonstrate this approach using a data set of migrating semipalmated sandpipers (Calidris pussila) for which we extend existing stopover models to allow for individuals to have different behaviour in terms of their stopover duration at the site. We demonstrate the use of reversible jump MCMC methods to derive posterior distributions for the model parameters and the models, simultaneously. The algorithm moves between models with different numbers of arrival groups as well as between models with different numbers of behavioural groups. The approach is shown to provide new ecological insights about the stopover behaviour of semipalmated sandpipers but is generally applicable to any population in which animals arrive in groups and potentially exhibit heterogeneity in terms of one or more other processes.     

Nanosized magnetite in low cost materials for remediation of water polluted with toxic metals,azo- and antraquinonic dyes

Nanosized magnetite has emerged as an adsorbent of pollutants in water remediation. Nanoadsorbents include magnetic iron oxide and its modifiers/stabilizers, such as carbon, silica, clay, organic moieties (polymers, aminoacids, and fatty acids) and other inorganic oxides. This review is focused on the recent developments on the synthesis and use of magnetic nanoparticles and nanocomposites in the treatment of contaminated water. The emphasis is on the influence of the iron oxide modifiers on some properties of interest such as size, BET area, and magnetization. The characteristics of these nanomaterials are related to their ability to eliminate heavy metal ions and dyes from wastewater. Comparative analysis of the actual literature was performed aiming to present the magnetic material, its preparation methodology and performance in the elimination of the selected pollutants. Vast information has been properly summarized according to the materials, their properties and preferential affinity for selected contaminants. The mechanisms governing nanomaterial’s formation as well as the interactions with heavy metals and dyes have been carefully analyzed and associated to their efficiency.     

The effects of an abnormal decrease in temperature on the Eastern Pacific reef-building coral Pocillopora verrucosa

Coral bleaching events are associated with abnormal increases in temperature, such as those produced during El Niño. Recently, a breakdown in the coral–dinoflagellate (genus Symbiodinium) endosymbiosis has been documented in corals exposed to anomalously cold-water temperatures associated with La Niña events. Given the ecological significance of such events, as well as the threat of global climate change, surprisingly little is known about the physiological response of corals to cold stress. This study evaluated some physiological effects of continuous temperature decline in colonies of the eastern Pacific reef-building coral Pocillopora verrucosa. Twenty days of incubation at 18.5–19.0 °C resulted in a substantial decrease in holobiont lipid and Chla content, as well as an increase in Symbiodinium density. These observations suggest a combination of symbiont acclimation due to the temperature decline and reallocation of carbon toward algal growth as opposed to translocation to the host coral. With a decreased availability of symbiont-derived carbon, the coral likely catabolized storage lipids in order to survive the stress event. Despite this stress and some tissue necrosis, no mortality was noted and corals recovered quickly when returned to the ambient temperature. As these results are in marked contrast to similar studies investigating elevated temperature on this coral from this same location, Pocillopora in the Mexican Central Pacific may be more prone to long-term damage and mortality during periods of ocean warming as opposed to ocean cooling.     

Determination of polychlorinated biphenyl and polycyclic aromatic hydrocarbon marine regional Sediment Quality Guidelines within the European Water Framework Directive

Marine regional Sediment Quality Guidelines (SQG) for polychlorinated biphenyls (PCB) and polycyclic aromatic hydrocarbons (PAH) from the Basque coast (SE Bay of Biscay) were determined, on the basis of sediment chemistry, toxicity and benthic community disturbance from analysis of 756 estuarine and coastal samples. The SQG were calculated using a percentile approach (based upon effect and non-effect data), using non-normalised and normalised concentration, by total organic carbon. However, normalisation by total organic carbon did not result in any improvement in accuracy compared with non-normalised values. Hence, this study proposes non-normalised SQG values for assessment of the chemical and physicochemical status in marine waters in the Basque Country, within the Water Framework Directive: 24.6–29 μg kg^?1 for total PCBs; 164–285 μg kg^?1 for low molecular weight PAH; 922–1537 μg kg^?1 for high molecular weight PAH; and 1607–2617 μg kg^?1 for total PAH.     

Platinum in PM2.5 of the metropolitan area of Mexico City

The increase in platinum (Pt) in the airborne particulate matter with size ≤2.5 µm (PM_2.5) in urban environments may be interpreted as result of the abrasion and deterioration of automobile catalyst. Nowadays, about four million vehicles in Mexico City use catalytic converters, which means that their impact should be considered. In order to evaluate the contribution of Pt to environmental pollution of the metropolitan area of Mexico City (MAMC), airborne PM_2.5 was collected at five different sites in the urban area (NW, NE, C, SW, SE) in 2011 during April (dry-warm season), August (rainy season) and December (dry-cold season). Analytical determinations were carried out using a ICP-MS with a collision cell and kinetic energy discrimination. The analytical and instrument performance was evaluated with standard road dust reference material (BCR-723). Median Pt concentration in the analyzed particulate was is 38.4 pg m^?3 (minimal value 1 pg m^?3 maximal value 79 pg m^?3). Obtained Pt concentrations are higher than those reported for other urban areas. Spatial variation shows that SW had Pt concentration significantly higher than NW and C only. Seasonal variation shows that Pt median was higher in rainy season than in both dry seasons. A comparison of these results with previously reported data of PM₁₀ from 1991 and 2003 in the same studied area shows a worrying increase in the concentration of Pt in the air environment of MAMC.     

Identification and assessment of water pollution as a consequence of a leachate plume migration from a municipal landfill site (Tucumán,Argentina)

Landfills constitute potential sources of different pollutants that could generate human health and environmental problems. While some landfills currently work under the protection of a bottom liner with leachate collection, it was demonstrated that migration could take place even yet with these cautions. The purpose of this paper is to assess the pollution caused by a leachate plume from a municipal landfill that is affecting both groundwater and surface waters. The research was carried out at Pacará Pintado landfill in northwestern Argentina. Analysis of water samples indicates that leachate is affecting groundwater under the landfill area and an abandoned river channel hydraulically connected. In the center of the landfill area, the plume is anoxic and sulfate, nitrate, iron and manganese reduction zones were identified. Leachate plume presented high concentration of organic matter, Fe, Mn, NH₄ ⁺, Cl^? and Cr reaching an extension of 900 m. The presence of a leachate plume in a landfill site with a single liner system implies that the use of this groundwater pollution control method alone is not enough especially if permeable sediments are present below.     

Metals in the sediment and liver of four fish species from different trophic levels in Tisza River,Serbia

In aquatic environments metals originate from various natural and anthropogenic sources. The degree of contamination in fish tissues depends on the pollutant, fish species, their mode of feeding, sampling site and trophic level. This study presents concentrations of Al, As, Cd, Co, Cr, Cu, Fe, Hg, Mn, Ni, Pb, Se, Sr and Zn in sediment and liver of four ecologically different fish species: piscivorous northern pike (Esox lucius L.), benthivorous sterlet (Acipenser ruthenus L.) and silver bream (Brama brama L.), and omnivorous common carp (Cyprinus carpio L.). Fish were caught at four sites along the stretch of the River Tisza in Serbia during October 2010. The concentrations of metals have been assessed using the inductively coupled plasma – optical emission spectrometry. Results revealed that metals with the highest values in sediment and fish samples were Al and Fe, respectively and sometimes concentrations of Zn are in the same order of magnitude as Fe concentrations. The highest concentration of metals was recorded in omnivorous common carp.     

Characterization and Release Kinetics of Allylthiosufinate and its Transforments from Poly(d,l-Lactide) Microspheres

In this work was described poly(d,l-lactide) microwave synthesis using tin(II) 2-ethylhexanoate initiated ring-opening polymerization. Polymerization was performed at 100 °C with monomer to initiator molar ratio ([M]/[I]) of 5,000 in 30 min. The achieved number average molar mass of obtained polymers (determined by gel permeation chromatography) was 102,320 g/mol, with the polydispersion index, Q, 2.80. Structural characterization was performed by FT-IR spectroscopy followed characteristic bands. For applicative purposes the obtained polymer was purified during the procedure of microsphere preparation. Biodegradable microspheres prepared from poly(d,l-lactide) have been widely studied in recent years and have become well established controlled drug delivery systems. In this work microspheres were loaded with allyl thiosulfinate (allicin) and its transforments products (ajoene and vinyldithiine), as pharmacological active substances. The morphology of the microspheres was analyzed using a scanning electron microscope. Allicin was synthesized by acid oxidation of allyl disufide and purification of obtained products by liquid–liquid extraction with diethyl ether. Obtained allicin, purity 73%, was transformed using microwave in acetone solution, at solvent boiling temperature, for 5 min. For the quality and quantity analysis of allicin and its transformation process was used LC/MS chromatography. (E)- and (Z)-ajoene were detected at retention time 3.1 and 3.3 min, respectively, whence 3-vynil-4H-1,2-dithiine and 2-vynil-4H-1,3-dithiine were detected at 4.3 and 4.8 min, respectively. Retention time of allicin was 2.93 min, according to liquid chromatography results. HPLC method was used for assessment of pharmaceutical substances (alicine and alicine transforments) releasing from microspheres at room temperature in solutions with different pH (pH = 3 and pH = 8) for 24 h.