Study of radioactive contamination in silts and aerosols at Aldama City,Mexico, due to the operation of a yellow-cake processing plant

The city of Aldama, Chihuahua, Mexico is located 30 km NNE of Chihuahua city. Three high-volume collectors with PM₁₀ heads were placed in specific locations in Aldama during the year 2011 to measure radioisotope concentrations in the air. The city area of 16 km² was divided into 64 squares of 500 × 500 m. At the vertices of the grid, silt samples were taken between January and June 2011, before the rains began. The concentrations of natural, cosmogenic, and anthropogenic radioactive isotopes were calculated in both filters and silts samples. The isotopes selected for the measurement were ²³⁸U, ²³²Th, ⁷Be, ¹³⁷Cs, and ⁴⁰K. Measurements of PM₁₀ and silts were performed during 2011, coinciding with the accident at Fukushima, Japan, on March 11. For this reason, we could see the ¹³⁷Cs in PM₁₀ increase between April and July; with the arrival of the rains, the ¹³⁷Cs concentration began to decrease in the air. The concentration of PM₁₀ measured by the equipment located at the Mexican Uranium plant (URAMEX, initials in Spanish) that was processing radioactive ores exceeded the standard values in February and March, when the air velocity increases. At City Hall, the concentration of PM₁₀ surpassed the value of the standard between May and July. This increased concentration is likely due to increased automobile traffic because City Hall is located in the city center. At a private home, the concentration of PM₁₀ surpassed the standard on several days during the year because the home is located on the outskirts of the city, where most of the streets are not paved. Due to the high concentrations of PM₁₀, especially at the collection point located at the private home, it is necessary to start taking steps to mitigate their spread before they cause health problems in the younger population and in older adults.

Implications: The radioisotope content found in the PM₁₀ confirms that the decision to place the Mexican Uranium plant (URAMEX, initials in Spanish) processing radioactive ores near the town of Aldama was not well thought out. Because the monitoring work was carried out in 2011 and coincided with the Fukushima accident, an increased concentration of ¹³⁷Cs could be detected in the PM₁₀. We made recommendations to the municipal authorities of the city to mitigate the concentration of particles in the air.     

Coarse and fine aerosol source apportionment in Rio de Janeiro,Brazil

The metropolitan area of Rio de Janeiro is one of the twenty biggest urban agglomerations in the world, with 11 million inhabitants in the metropolitan area, and has a high population density, with 1700 hab. km^?2. For this aerosol source apportionment study, the atmospheric aerosol sampling was performed at ten sites distributed in different locations of the metropolitan area from September/2003 to December/2005, with sampling during 24 h on a weekly basis. Stacked filter units (SFU) were used to collect fine and coarse aerosol particles with a flow rate of 17 L min^?1. In both size fractions trace elements were analyzed by Inductively Coupled Plasma-Mass Spectrometry (ICP-MS) as well as water-soluble species by Ion-Chromatography (IC). Also gravimetric analysis and reflectance measurements provided aerosol mass and black carbon concentrations. Very good detection limits for up to 42 species were obtained. Mean annual PM₁₀ mass concentration ranged from 20 to 37 μg m^?3, values that are within the Brazilian air quality standards. Receptor models such as principal factor analysis, cluster analysis and absolute principal factor analysis were applied in order to identify and quantify the aerosol sources. For fine and coarse modes, circa of 100% of the measured mass was quantitatively apportioned to relatively few identified aerosol sources. A very similar and consistent source apportionment was obtained for both fine and coarse modes for all 10 sampling sites. Soil dust is an important component, accounting for 22–72% and for 25–48% of the coarse and fine mass respectively. On the other hand, anthropogenic sources as vehicle traffic and oil combustion represent a relatively high contribution (52–75%) of the fine aerosol mass. The joint use of ICP-MS and IC analysis of species in aerosols has proven to be reliable and feasible for the analysis of large amount of samples, and the coupling with receptor models provided an excellent method for quantitative aerosol source apportionment in large urban areas.     

Environmental impact reduction through ecological planning at Bahia Magdalena, Mexico

For analyzing basic marine and coastal characteristics we selected the potential sites where shrimp culture could be developed in a large coastal zone, Bahia Magdalena, Baja California Sur, Mexico. Based on our analysis, 6 sites were preselected and field stages of work were then developed to assess the precise suitability of each site in order to develop the proposed aquaculture activities. In ranking the suitability we were able to recommend the most appropriate places to develop shrimp culture in this region. Also, knowing the exact biological, physico-chemical and social environment, we determined the best species to cultivate, the recommended total area and the methodology to be used to lessen the environmental impact and to obtain the maximum profitability Our methodology could be used not only to select appropriate sites for shrimp culture in other coastal lagoons, but it also could be applied to assess the suitability in a quick and accurate way, of any other production activity in coastal zones.     

Hazardous and essential trace elements profile in the different soft tissues of Lithophaga lithophaga (Linnaeus, 1758) from Southern Adriatic Sea (Italy)

A characterization study of 7 hazardous (Hg, Pb, Cd, As, Cr, U, and Ni) and 11 essential (Co, Mo, Se, Cu, Zn, V, Ca, Al, Sr, Mn, and Fe) trace elements in date mussels (Lithophaga lithophaga,Linnaeus, 1758) was carried out by inductively coupled plasma mass spectrometer. Date mussels (231 individuals), caught in the Gulf of Manfredonia (Southern Italy), were divided into 4 size-related groups. The different tissues (muscle, stomach, hepatopancreas and rest of soft tissues) were separated and analyzed to study the capability of absorption of this species. No particular differences were reported on the basis of the shell size; the soft tissues play an important role on the accumulation levels of hazardous and essential trace elements. These marine animals may be considered a good bioindicator of marine environmental pollution for their longevity and habitat permanence peculiarities.     

Native plant restoration combats environmental change: development of carbon and nitrogen sequestration capacity using small cordgrass in European salt marshes

Restoration of salt marshes is critical in the context of climate change and eutrophication of coastal waters because their vegetation and sediments may act as carbon and nitrogen sinks. Our primary objectives were to quantify carbon (C) and nitrogen (N) stocks and sequestration rates in restored marshes dominated by Spartina maritima to provide support for restoration and management strategies that may offset negative aspects of eutrophication and climate change in estuarine ecosystems. Sediment C content was between ca. 13 mg C g^?1and sediment N content was ca. 1.8 mg N g^?1. The highest C content for S. maritima was recorded in leaves and stems (ca. 420 mg C g^?1) and the lowest in roots (361?±?4 mg C g^?1). S. maritima also concentrated more N in its leaves (31?±?1 mg N g^?1) than in other organs. C stock in the restored marshes was 29.6 t C ha^?1; ca. 16 % was stored in S. maritima tissues. N stock was 3.6 t N ha^?1, with 8.3 % stored in S. maritima. Our results showed that the S. maritima restored marshes, 2.5 years after planting, were sequestering atmospheric C and, therefore, provide some mitigation for global warming. Stands are also capturing nitrogen and reducing eutrophication. The concentrations of C and N contents in sediments, and cordgrass relative cover of 62 %, and low below-ground biomass (BGB) suggest restored marshes can sequester more C and N. S. maritima plantations in low marshes replace bare sediments and invasive populations of exotic Spartina densiflora and increase the C and N sequestration capacity of the marsh by increasing biomass production and accumulation.     

13C-labeling shows the effect of hierarchy on the carbon gain of individuals and functional groups in dense field stands

Measurements of resource capture by individuals, species, or functional groups coexisting in field stands improve our ability to investigate the ecophysiological basis of plant competition. But methodological and technical difficulties have limited the use of such measurements. Carbon capture, in particular, is difficult to asses in heterogeneous, dense field stands. Here we present a new approach to measure in situ daily gross carbon gain of individuals. It is based on measuring the 13C content of shoots after a few hours of continuous labeling of all assimilated CO2. The technique is simple and has few assumptions. A new, fully mobile facility was developed, capable of providing a labeling environment with a CO2 concentration close to atmospheric air and known, constant 13C-enrichment, while maintaining temperature and relative humidity within ambient values. This facility was used in seminatural grasslands of Germany and Argentina to explore the relationship between size and carbon gain of individuals of coexisting species growing in contrasting hierarchical positions, and to analyze the carbon gain of functional groups. In general, carbon gain per unit shoot mass increased with increasing size among small individuals, but it became independent of size among the largest ones. In consequence, competition appeared to be size asymmetric between subordinate individuals but size symmetric between dominant individuals. When comparing functional groups, the carbon gain per unit shoot mass of rosette dicots vs. grasses reflected not their relative contribution to stand biomass, but their hierarchical position: irrespectively of mass or growth form, being taller than neighbors was most important in determining carbon gain per unit shoot mass. We believe these results show that in situ measurements of carbon gain can provide valuable insight in field studies of plant competition.     

Thermoplasticized Pectin by Extrusion/Thermo-Compression for Film Industrial Application

Journal of Polymers and the Environment - Researches for the development of materials with less environmental impact have been more common. Pectin is a natural polysaccharide, presenting in plants...     

Biological inventories and computer data bases: Their role in environmental assessments

An important goal of biological inventories is to provide information for environmental assessments of development projects and biodiversity conservation. Likewise, computer data bases have been proposed for efficient compilation and management of biological information. However, the attributes of biological inventories and computer data bases have not been examined with respect to environmental assessments. This article presents a case study in Mexico to analyze the current limitations of biological inventories for successful environmental assessments and biodiversity conservation in developing countries. Results demonstrate that, considering the objectives of environmental assessments and information constraints, computerized biological inventories should be assembled with a minimum of record fields: taxonomic data and georeferenced collection localities. Furthermore, it is proposed that environmental assessments should become a feedback to biological inventories and an important financial support to universities and research institutions in developing countries.