Conservation priorities for mammals in megadiverse Mexico: the efficiency of reserve networks.

A major goal of conservation biologists is to identify critical areas for the conservation of biological diversity and then strategically include them in an efficient system of reserves. In general, however, reserve networks have been selected for different objectives, and most countries lack an evaluation of their reserves' ability to represent a percentage of the national diversity. This paper evaluates the effectiveness of a network of reserves to represent the species of mammals in Mexico. The focus of the analyses is on species and site level, evaluating the representation of all terrestrial mammals in the 30 most important reserves. The representation of all species, endemic species, endangered species, and species with restricted distributions in the reserves was assessed and compared. Endemic or endangered species with restricted distributions were expected to be less represented in reserves than were widespread species. The most important reserves for the conservation of mammals were determined with the use of complementarity analyses. Priority sites for the representation of all the species currently absent from the reserve network were then selected. The results have broad applications for conservation. First, 82% of the mammal species from Mexico were represented in the reserve network, which covers a small portion (3.8%) of the country. Second, this percentage is certainly larger as several reserves were not evaluated due to a lack of data. A priority for a national conservation strategy could be to conduct biological surveys in those reserves lacking inventories to evaluate their contribution to conservation. Third, in spite of its demonstrated value, Mexico's reserve network can be improved by designating complementary areas. Additional priority sites, where reserves are required to represent most gap species in the network, were identified. Finally, it is clear that this reserve network has limitations for maintaining biodiversity and ecosystem services at regional scales. A comprehensive conservation strategy has, therefore, to incorporate mechanisms that enhance the value of human-dominated landscapes for the maintenance of biodiversity.     

Analytical solutions for reactive transport under an infiltration-redistribution cycle

Transport of reactive solute in unsaturated soils under an infiltration-redistribution cycle is investigated. The study is based on the model of vertical flow and transport in the unsaturated zone proposed by Indelman et al. [J. Contam. Hydrol. 32 (1998) 77], and generalizes it by accounting for linear nonequilibrium kinetics. An exact analytical solution is derived for an irreversible desorption reaction. The transport of solute obeying linear kinetics is modeled by assuming equilibrium during the redistribution stage. The model which accounts for nonequilibrium during the infiltration and assumes equilibrium at the redistribution stage is termed partial equilibrium infiltration-redistribution model (PEIRM). It allows to derive approximate closed form solutions for transport in one-dimensional homogeneous soils. These solutions are further applied to computing the field-scale concentration by adopting the Dagan and Bresler [Soil Sci. Soc. Am. J. 43 (1979) 461] column model. The effect of soil heterogeneity on the solute spread is investigated by modeling the hydraulic saturated conductivity as a random function of horizontal coordinates. The quality of the PEIRM is illustrated by calculating the critical values of the Damk?hler number which provide the achievable accuracy in estimating the solute mass in the mobile phase. The distinguishing feature of transport during the infiltration-redistribution cycle as compared to that of infiltration only is the finite depth of solute penetration. For irreversible desorption, the maximum solute penetration W/theta(r) is determined by the amount of applied water W and the residual water content theta(r). For sorption-desorption kinetics, the maximum depth of penetration z(r)(e, infinity ) also depends on the ratio between the rate of application and the column-saturated conductivity. It is shown that z(r)(e, infinity ) is bounded between the depths W/(theta(r)+K(d)) and W/theta(r) corresponding to the maximum solute penetration for equilibrium transport and for irreversible desorption, respectively. This feature of solute penetration explains the unusual phenomena of plume contraction after an initial period of spreading [Lessoff, S.C., Indelman, P., Dagan, G., 2002. Solute transport in infiltration-redistribution cycles in heterogeneous soils. In Raats, P.A.C., Smiles, D.,Warrick, A.W. (Eds), Environmental Mechanics: Water, Mass and Energy Transport in the Biosphere. American Geophysical Union, pp. 133-144]. Unlike transport under equilibrium conditions, when the solute is completely concentrated at the front, the solute under nonequilibrium conditions is spread out behind the front. Heterogeneity leads to additional spreading of the plume.     

Spatial and seasonal dynamics of phosphorous and physicochemical variables in the Negro River Estuary (Argentina): a preliminary approach

Environmental Science and Pollution Research - Nutrient discharge into rivers and estuaries and the factors that control it need to be further understood to decrease the risk of harmful algae...     

Effects of exposure to environmental pollutants on mitochondrial DNA copy number: a meta-analysis

Environmental Science and Pollution Research - Exposure to environmental pollutants has been associated with alteration on relative levels of mitochondrial DNA copy number (mtDNAcn). However, the...     

Global burned-land estimation in Latin America using MODIS composite data.

This paper presents results of the AQL2004 project, which has been develope within the GOFC-GOLD Latin American network of remote sensing and forest fires (RedLatif). The project intended to obtain monthly burned-land maps of the entire region, from Mexico to Patagonia, using MODIS (moderate-resolution imaging spectroradiometer) reflectance data. The project has been organized in three different phases: acquisition and preprocessing of satellite data; discrimination of burned pixels; and validation of results. In the first phase, input data consisting of 32-day composites of MODIS 500-m reflectance data generated by the Global Land Cover Facility (GLCF) of the University of Maryland (College Park, Maryland, U.S.A.) were collected and processed. The discrimination of burned areas was addressed in two steps: searching for "burned core" pixels using postfire spectral indices and multitemporal change detection and mapping of burned scars using contextual techniques. The validation phase was based on visual analysis of Landsat and CBERS (China-Brazil Earth Resources Satellite) images. Validation of the burned-land category showed an agreement ranging from 30% to 60%, depending on the ecosystem and vegetation species present. The total burned area for the entire year was estimated to be 153 215 km2. The most affected countries in relation to their territory were Cuba, Colombia, Bolivia, and Venezuela. Burned areas were found in most land covers; herbaceous vegetation (savannas and grasslands) presented the highest proportions of burned area, while perennial forest had the lowest proportions. The importance of croplands in the total burned area should be taken with reserve, since this cover presented the highest commission errors. The importance of generating systematic products of burned land areas for different ecological processes is emphasized.     

Environmental impact assessment of non-wood based pulp production by soda-anthraquinone pulping process

Paper pulp manufacturing is the main non-food industrial utilization of plant biomass. Non-wood and agricultural residues are potential raw materials in the production of specialty papers. This chapter aims to quantify the environmental impacts associated with non-wood high quality paper pulp manufacture via soda-anthraquinone (AQ) cooking process by means of the application of LCA methodology in a cradle-to-gate analysis. Hemp (Cannabis sativa) and Flax (Linum usitatissimum) were evaluated as raw materials for the production of high quality non-porous pulp. A specialty paper pulp mill was analysed in detail and process chain was divided in six subsystems: agricultural activities, chemicals production, electricity production, transport, pulp production and waste treatment. Inventory data came from interviews and surveys (on-site measurements). When necessary, the data were completed with bibliographic resources.Abiotic resources depletion (AD), global warming (GW), ozone layer depletion (OLD), human toxicity (HT), ecotoxicity, photochemical oxidant formation (POF), acidification (A) and eutrophication (E) were the impact categories analysed in this study. According to the results, the environmental impact is mainly caused by the production of chemicals, electricity and fibres (agricultural activities) due to greenhouse gases emissions, phosphorous and nitrogen compounds emissions. The activities inside the pulp mill present minor contribution to almost all impact categories, excluding GW (15%) and E (6%) as well as OLD (25%). This study provides useful information for non-wood based industries related not only to pulp manufacture but also to panels or biorefineries with the aim of increasing their sustainability.     

Multi-scale land cover dynamics of semiarid scrubland in Baja California,Mexico

Land use and cover changes trigger multi-factorial responses with tangible and intangible effects. Driving forces governing changes are scale-, place- and time-dependent; because of their complexity, a multi-scalar analysis is required to determine conjoint causation. Studies using multi-scalar approach in semiarid scrubland ecosystems are scanty. This paper investigates land use changes on the largest semiarid scrubland ecosystem of Mexico, the Baja California Peninsula, using a multi-scalar analysis approach. It further provides insight into the likely underlying causes for land use trends. Multi-temporal databases were compiled for 1978, 1990, 2000 and 2003 from various sources; population was projected for the same years. Land cover processes were validated through intensive fieldwork. Map overlapping with the aid of geographic information systems allowed computation of land cover transformation rates. New algorithms were developed to better understand land cover trends. Multi-variate analysis was also performed to provide a synthetic statistical overview. Results showed that land cover change occurred at different times, at variable scales, due to distinct drivers. As a consequence, the current regional scenario has been shaped by distinguishable socio-economic changes. The semiarid scrubland ecosystems in the Baja California Peninsula experienced contrasting trends detectable only at site and local scales. Regionally, the replacement of original vegetation (scrubland) for other land cover category is following trends similar to those in the rest of Mexico and most semiarid ecosystems worldwide. These findings support the hypothesis that land use and cover changes must be analyzed at different times and scales to deeply understand underlying forces.     

3D Numerical Model of the Thermal Interaction Between Sediment–Water–Atmosphere

This paper describes a three-dimensional numerical model of heat flux using finite-difference approximation for the simulation, prediction, and visualization of sediment, water, and air temperature, applied in Villa del Mar saltmarsh, Bahía Blanca Estuary, Argentina. To make this computation, we develop an open-source software tool called Hemera 1.0 which is characterized by having little complexity and low hardware requirements. The model considers three heat transfer processes: diffusion, convection, and radiation, using bulk aerodynamic formulas as boundary conditions between the interfaces. The aforementioned model was applied for the month of January 2009. The model reproduced adequately the physical processes of the heat balance and showed an adequate response to changes in the boundary conditions. In addition, according to the model design, meteorological and oceanographic data and some soil properties are the only data input used for modeling. It is easily adaptable to other environments such us lakes and reservoirs, among others, in order to carry out similar studies.     

Chemical characterization and factor analysis of PM2.5 in two sites of Monterrey, Mexico

The Monterrey Metropolitan Area (MMA) has shown a high concentration of PM2.5 in its atmosphere since 2003. The contribution of possible sources of primary PM2.5 and its precursors is not known. In this paper we present the results of analyzing the chemical composition of sixty 24-hr samples of PM2.5 to determine possible sources of PM2.5 in the MMA. The samples were collected at the northeast and southeast of the MMA between November 22 and December 12, 2007, using low-volume devices. Teflon and quartz filters were used to collect the samples. The concentrations of 16 airborne trace elements were determined using x-ray fluorescence (XRF). Anions and cations were determined using ion chromatography. Organic carbon (OC) and elemental carbon (EC) were determined by thermal optical analysis. The results show that Ca had the maximum mean concentration of all elements studied, followed by S. Enrichment factors above 50 were calculated for S, Cl, Cu, Zn, Br and Pb. This indicates that these elements may come from anthropogenic sources. Overall, the major average components of PM2.5 were OC (41.7%), SO4(2-) (22.9%), EC (7.4%), crustal material (11.4%), and NO3- (12.6%), which altogether accounted for 96% of the mass. Statistically, we did not find any difference in SO4(2-) concentrations between the two sites. The fraction of secondary organic carbon was between 24% and 34%. The results of the factor analysis performed over 10 metals and OC and EC show that there are three main sources of PM2.5: crustal material and vehicle exhaust; industrial activity; and fuel oil burning. The results show that SO4(2-), OC, and crustal material are important components of PM2.5 in MMA. Further work is necessary to evaluate the proportion of secondary inorganic and organic aerosol in order to have a better understanding of the sources and precursors of aerosols in the MMA.