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331.
Matías Feijoo Enrique P. Lessa Rocío Loizaga de Castro Enrique A. Crespo 《Marine Biology》2011,158(8):1857-1867
Several major breeding areas have been defined for the South American sea lion (Otaria flavescens) along the Atlantic Ocean including the Uruguayan and Patagonian coasts. Together with a documented and severe reduction
in population sizes caused by commercial hunting in the last century, these areas show opposite population trends. While Patagonian
populations are recovering since hunting ceased, Uruguayan populations are declining. In this context, population genetic
structure and genetic diversity were studied for the first time with both nuclear (microsatellites) and mitochondrial (control
region) markers together. Alternative scenarios were found for both markers. While mitochondrial marker showed geographically
structured populations, the nuclear loci showed a lack of geographical structure. These opposite patterns in genetic structure
could be explained by female phylopatry and high male dispersion. The reduction in population size caused by commercial hunting
did not leave a detectable footprint of bottleneck at the genetic level. 相似文献
332.
Gert Everaert Pieter BoetsKoen Lock Sašo D?eroskiPeter L.M. Goethals 《Ecological modelling》2011,222(14):2202-2212
Polder lakes in Flanders are stagnant waters that were flooded by the sea in the past. Several of these systems are colonized by exotic species, but have hardly been studied until present. The aim of the present study was: (1) to assess the influence of exotic macrobenthic species on the outcome of the Multimetric Macroinvertebrate Index Flanders (MMIF) and (2) to use classification trees for evaluating to what extent physical-chemical characteristics affect the presence of exotic species.In total, 27 mollusc and 10 macro-crustacean species were present in the monitored lakes of which respectively five and four were exotic. The exclusion of the exotic species from the MMIF resulted in a significant decline of this ecological index (−0.03 ± 0.04; p = 0.00). This elimination often resulted into a lower ecological water quality class and more samples were classified into the bad and poor ecological water quality classes.Single-target classification trees for Gammarus tigrinus and Potamopyrgus antipodarum were constructed, relating environmental parameters and ecological status (MMIF) to the occurrence of both exotic invasive species. The major advantages of using single-target classification trees are the transparency of the rule sets and the possibility to use relatively small datasets. However, this classification technique only predicts a single-target attribute and the trees of the different species are often hard to integrate and use for water managers. As a solution, a multi-target approach was used in the present study. Exotic molluscs and crustaceans communities were modelled based on environmental parameters and the ecological status (MMIF) using multi-target classification trees. Multi-target classification trees can be used in management planning and investment decisions as they can lead to integrated decisions for the whole set of exotic species and avoid the construction of many models for each individual species. These trees provide general insights concerning the occurrence patterns of individual crustaceans and molluscs in an integrated way. 相似文献
333.
Monferrán MV Galanti LN Bonansea RI Amé MV Wunderlin DA 《Journal of environmental monitoring : JEM》2011,13(2):398-409
We report a combined two-year seasonal monitoring of Suquía River basin using both chemical parameters and biomarkers measured in Jenynsia multidentata, aiming to correlate external levels of contaminants with the response of oxidative stress biomarkers in this fish. Identified pollution sources correspond to city sewage as well as agricultural and small industry activities downstream from Córdoba city. Physicochemical parameters integrated into a water quality index (WQI) were measured in Suquía River during dry and wet seasons. Ag, Mn, Cu, Cr, Ni, Fe, Pb and Zn were also monitored in water and sediment samples. Biomarkers include detoxication and antioxidant enzymes: catalase (CAT), glutathione peroxidase (GPX), glutathione S-transferase (GST) and glutathione reductase (GR). Enzymes showed a pollution dependent response, with increased activities in fish collected close to the sewage exit and progressive drop further downstream, matching changes in the Water Quality index. The combined use of biomarkers with water quality parameters allowed both the identification of pollution sources and the evaluation of effects of contaminants on the aquatic biota. 相似文献
334.
A monitoring program of cyanobacteria and cyanotoxins in the framework of the surveillance of the Water Treatment Plant efficiency of the municipality of Santa Comba D?o (Portugal) was conducted from 1994 until 2007. With these data we aimed to answer the question, are MCs produced evenly over the years in a single water body? Samples were taken by the local health authorities in the site of the Water treatment plant and analyzed for total phytoplankton, cyanobacteria and the hepatotoxic cyanotoxins microcystins (MCs). Apart from 1999 and 2000, cyanobacteria represented a high proportion of total phytoplankton, attaining during several months of the year more than 90% of total phytoplankton density. A total of 24 cyanobacteria species were identified and Microcystis aeruginosa, Anabaena flos-aquae and Aphanizomenon flos-aquae were the main potentially toxic cyanobacteria species present throughout the period. MC concentration varied between 0.3 μg MC-LR eq l?1 in October 98 and 87.0 μg MC-LR eq l?1 in September 2001. The evolution of the average cell quota does not reveal any especial trend, although in 2001 the quota was the highest but not significantly different from the other years. The threshold limit of 5000 cells per ml of Microcystis aeruginosa should be taken into consideration in monitoring programs because the 10,000 cells per ml proposed by several other national programs might not be enough to prevent human health risks. Due to high annual variation in MC cell quota, monitoring programs of cyanobacteria and MC should be extended in time, since short term studies do not provide us the data needed for a safe management of a water body used for human purposes. 相似文献
335.
Susana Torno Javier Toraño Mario Menendez Malcolm Gent Cristina Allende 《Environmental Fluid Mechanics》2011,11(1):99-112
Landfill sites have been the most common way of eliminating solid urban waste, as well as that of public and mining wastes.
Landfill sites are a constant source of environmental pollution and wind is the most important contributing factor to air
pollution, due to the erosion which it produces over the landfill site surfaces, transporting dust away from the source point.
This causes serious risks for human health and general dirt in the surrounding areas of the landfill site. The result of dust
air pollution produced in a landfill site is analysed through CFD3D (Computational Fluid Dynamics) by joining the LIDAR (Light
Detection and Ranging) technique and Ansys CFX 10.0 software. The CFD simulations determine the wind velocity distribution
on the landfill site surface and the different particle threshold friction velocities which determine the dust emission in
multiphase simulations (air-particles). These simulations are validated from field data obtained in three measurement programmes
for each type of landfill site surface treatment which has been studied. It was determined that the superficial landfill site
treatment with the lowest air pollution is tall grass and bushes. The methodology used can be applied to the dust emission
calculation in the design or evaluation of other landfill sites. 相似文献
336.
Pedro Gon?alves Rodrigues Lu��s Moreira Gon?alves Paulo Jorge Magalh?es Jo?o Grosso Pacheco Jos�� Ant��nio Rodrigues Aquiles Ara��jo Barros 《Environmental Chemistry Letters》2011,9(3):405-410
An major research area in environmental chemistry is the development of methods for the analysis of biomarkers. Metallothioneins
are used as biomarkers in studies of heavy metals exposure in water, because metallothioneins are synthesized and accumulated
when organisms are exposed to toxic concentrations of pollutants. In this work, simple and sensitive voltammetric methods
were developed for metallothionein and copper (II) determinations in fish liver Lepomis gibbosus. Both analytical methodologies were optimized and applied to samples extracted from individuals previously submitted to sub-lethal
toxicological trials with copper sulphate (CuSO4) and cadmium chloride (CdCl2). The obtained results showed that both methods are very precise, sensitive, and involve simple sample preparation processes.
Moreover, metallothioneins showed better correlation with the toxic exposure than Cu2+. To the best of our knowledge, this is the first time that hepatic metallothioneins and Cu2+ contents are voltammetrically determined in order to be compared in their function as heavy metal biological indicators. 相似文献
337.
da Silveira RP Rodrigues AP Santelli RE Cordeiro RC Bidone ED 《Environmental monitoring and assessment》2011,181(1-4):165-173
This study addressed the identification and monitoring of pollution sources of terrestrial origin in rivers (domestic sewage and industrial effluents) and critical fluvial segments in highly polluted environments under tidal influence (mixing marine and continental sources) from Guanabara Bay Basin, Rio de Janeiro, Brazil. The mass balance of contaminants was determined in conditions of continuous flow (low tide) during dry season (lower dilution capability). The results allowed the evaluation of the potential of contaminant mass generation by the different river segments and the estimation of their natural and anthropogenic components. The water quality of Igua?ú and Sarapuí Rivers were evaluated for metals and biochemical oxygen demand. The method gave an excellent response, including the possibility of sources identification and contaminated river segments ranking. The approach also offers fast execution and data interpretation, being highly efficient. 相似文献
338.
Samuel Barsanelli Costa Roberto Wagner Louren?o 《Environmental monitoring and assessment》2011,172(1-4):329-337
Noise mapping has been used as an instrument for assessment of environmental noise, helping to support decision making on urban planning. In Brazil, urban noise is not yet recognized as a major environmental problem by the government. Besides, cities that have databases to drive acoustic simulations, making use of advanced noise mapping systems, are rare. This study sought an alternative method of noise mapping through the use of geoprocessing, which is feasible for the Brazilian reality and for other developing countries. The area chosen for the study was the central zone of the city of Sorocaba, located in São Paulo State, Brazil. The proposed method was effective in the spatial evaluation of equivalent sound pressure level. The results showed an urban area with high noise levels that exceed the legal standard, posing a threat to the welfare of the population. 相似文献
339.
Salamún P Renčo M Miklisová D Hanzelová V 《Environmental monitoring and assessment》2011,183(1-4):451-464
Soil nematode communities (taxa composition, trophic structure, ecological indices) in the area of metallurgical factory (Oravské ferozliatinárske závody) in ?iroká, Northern Slovakia were investigated in 2009. The factory belongs to main sources of emissions originated by ferroalloy production in this region. Four sites (meadows) were selected in a downwind direction from the factory: site A was located 0.85 km far from the factory, and the other sites were maintained in approximately 2-km intervals from each other. Chemical analysis of soil samples showed low concentrations of heavy metals (As, Cd, Cr, Cu, Ni, Pb and Zn), with all values being under Slovak limit concentrations of heavy metals in soils. Only the Cd content in the soil sample from site A slightly exceeded the allowable threshold, but it was decreasing with the distance from the factory, similarly as remaining metals except Cr, with slightly increasing trend of concentration. Within 64 identified nematode genera, the Helicotylenchus, Paratylenchus, Pratylenchus, Acrobeloides, Cephalobus and Rhabditis were most common and eudominant. This was clearly reflected on the trophic structure of nematode communities, where plant feeding nematodes and bacteriovorous prevailed. Significant negative correlation (P?0.05) was observed between the abundance of bacteriovores and the concentration of Cu in the soil. On the other hand, fungivores showed significant correlation with Ni and Cr (P?0.05) as well as predators with Cd, Pb and Zn contents in the soil (P?0.01). The highly significant correlation (P?0.05; P?0.01) was found between As, Cd, Ni, Pb and Zn and Maturity Index 2-5. A negative relationship was detected between Maturity Index and the concentration of Cr in the soil (P?0.01). On the other hand, Cu was in positive correlation with MI values. The MI, reflecting the degree of disturbances and changes in the structure and function of the soil ecosystem, was found to be the most sensitive indicator among all used indices. 相似文献
340.
Coutellec Léo Bernard Pintureau 《Journal of Agricultural and Environmental Ethics》2013,26(1):207-230
Crop protection has a very long history during which new methods have been developed whilst, at the same time, the older ones have retained their usefulness in certain conditions. The diversity of agricultural land and production has meant that it was futile to search for a unique and definitive approach or technical solution and, instead, the central concept has always been one of integration, during all the period of pre-Green Revolution and again today within what we call a sustainable agriculture. On a global level, it would seem that the current situation does not fundamentally contradict this idea. Nevertheless, in recent years (since the Second World War), two important advances, presented as the definitive solutions to problems and potentially exceeding previously less effective ones, have led to this integrative approach being questioned. These are agrochemistry and agro-genetics. We will detail, here, the agro-environmental limits of these two “miracle solutions,” followed by a review from an ethical and an epistemological point of view. This enables us to demonstrate the relevance of integrated approaches in agriculture and leads to a definition of crop protection that forms part of a strong approach in sustainable development. By changing the semantics, the epistemic position and our vision of production, we arrive at the proposal of sustainable agriculture. 相似文献