Study of harmful algal blooms in a eutrophic pond, Bangladesh

The purpose of this research was to analyze the underlying mechanisms and contributing factors related to the seasonal dynamic of harmful algal blooms in a shallow eutrophic pond, Bangladesh during September 2005–July 2006. Two conspicuous events were noted simultaneously throughout the study period: high concentration of phosphate–phosphorus (>3.03; SD 1.29 mg l^???1) and permanent cyanobacterial blooms {>3,981.88 × 10³ cells l^???1 (SD 508.73)}. Cyanobacterial blooms were characterized by three abundance phases, each of which was associated with different ecological processes. High nitrate–nitrogen (>2.35; SD 0.83 mg l^???1), for example, was associated with high cyanobacterial abundance, while low nitrate–nitrogen (0.36; SD 0.2 mg l^???1) was recorded during moderate abundance phase. Extremely low NO₃–N/PO₄–P ratio (>3.55, SD 2.31) was recorded, and all blooming taxa were negatively correlated with this ratio. Cyanobacterial blooms were positively correlated with temperature (r?=?0.345) and pH (0.833; p?=?0.05) and negatively correlated with transparency (r?=???0.956; p?=?0.01). Although Anabaena showed similar relationship with water quality parameters as cyanobacteria, the co-dominant Microcystis exhibited negative relationship with temperature (r?=???0.386) and nitrate–nitrogen (r?=???0.172). This was attributed to excessive growth of Anabaena that suppressed Microcystis’s growth. Planktothrix was the third most dominant taxa, while Euglena was regarded as opportunistic.     

Comparison of USEPA digestion methods to heavy metals in soil samples

The use of appropriate analytical methods is of paramount importance for risk assessment and monitoring of potentially toxic metals in soils. In this sense, the objective of this study was to compare the effectiveness of two sample digestion methods, recommended by the Brazilian legislation for the management of contaminated areas (CONAMA 2009), aiming at the determination of environmentally available metal concentrations (USEPA 3050B, USEPA 3051A), as well as a total digestion method (USEPA 3052). Samples from 10 classes of soils were analyzed for Cu, Zn, Cd, Pb, Ni, and Hg. The results showed that the USEPA method 3051A is more efficient than the USEPA method 3050B in the extraction of levels considered environmentally available of Zn, Cu, Cd, Pb, and Ni. Besides providing a higher recovery of these elements, the method requires shorter digestion time, lower consumption of acids, and reduced risk of contamination. The USEPA method 3051A showed greater efficiency in Hg extraction in soils with higher clay content. Therefore, it is suitable for situations where a wide range of soils with different mineralogical characteristics are analyzed or in order to decrease the losses due to volatilization of the element in open systems.     

Impact of collection on bark regeneration from <Emphasis Type="Italic">Stryphnodendron rotundifolium</Emphasis> Mart. in northeastern Brazil

The growing commercial demand for products with medicinal use has caused overexploitation of several plant species worldwide. To prevent the decline of these populations, the collection of these resources should be done in a sustainable way considering the time of its replacement in natural stocks. This study was designed to identify the relationship between different intensities of extraction of bark from the trunk of Stryphnodendron rotundifolium Mart. and its regeneration speed. For this, we selected two areas of Cerrado in the Northeast of Brazil, where a monitoring experiment with duration of 24 months was performed. This experiment consisted in simulating different extractive damage to assess the regeneration of bark. In each area, we selected 20 individuals, among which four treatments with five repetitions were implemented. The data showed that in both study areas, the trees regenerated their shells faster when subjected to higher collection intensities. However, this regeneration was not related to variations in rainfall in the environment.     

Mimic Enzyme Based Cellulose Nanocrystals/PVA Nanocomposite Membranes for Enrichment of Biogas as a Natural Gas Substitute

Journal of Polymers and the Environment - Nanocomposite membranes promoted by mimic enzyme was developed and optimized for biogas upgrading at moderately high pressure applications up to...     

Thermal Degradation and Kinetic Parameters of Polyester and Poly(Lactic Acid) Blends Used in Shopping Bags in Brazil

In this work, synthetic polyester and poly(lactic acid) blends used as biodegradable shopping plastic bags were studied, together with control samples of polyethylene containing pro-oxidant catalysts (called “oxidegradable bags” in the market). Samples of these materials were weighed and buried in simulated soil for 3 months, and then studied by Thermal Analysis including a non-isothermal kinetic analysis. It was observed that although there was no significant mass loss in the period of the ageing, the activation energies for the thermal decomposition processes were substantially reduced for the biodegradable samples, but not for the oxidegradable ones.     

Individual specialization in the hunting wasp <Emphasis Type="Italic">Trypoxylon</Emphasis> (<Emphasis Type="Italic">Trypargilum</Emphasis>) <Emphasis Type="Italic">albonigrum</Emphasis> (Hymenoptera,Crabronidae)

Individual-level variation in resource use occurs in a broad array of vertebrate and invertebrate taxa and may have important ecological and evolutionary implications. In this study, we measured the degree of individual-level variation in prey preference of the hunting wasp Trypoxylon albonigrum, which inhabits the Atlantic Forest in southeastern Brazil. This wasp captures several orb-weaving spider genera to provision nests. Individuals consistently specialized on a narrow subset of the prey taxa consumed by the population, indicating the existence of significant individual-level variation in prey preferences. The population niche was broader in the wet season in terms of both prey size and taxa. In the case of prey size, the population niche expansion was achieved via increased individual niche breadths, whereas in the case of prey taxa, individual niches remained relatively constrained, and the population niche expanded via increased interindividual variation. The observed pattern suggests the possibility of functional trade-offs associated with the taxon of the consumed prey. The nature of the trade-offs remains unknown, but they are likely related to learning in searching and/or handling prey. We hypothesize that by specializing on specific prey taxa, individuals increase foraging efficiency, reducing foraging time and ultimately increasing reproductive success.     

Apples, Oranges, and Probabilities: Integrating Multiple Factors into Biodiversity Conservation with Consistency

We explore the problem of integrating some of the many factors involved in conservation planning by focusing on their effects on a common currency of conservation success, the probability of persistence. This approach has the potential to reduce many of the difficulties inherent in combining different pattern and process factors. For handling information expressed as probabilities, five area-selection methods are compared.     

Mercury pollution and childhood in Amazon riverside villages

Mercury is a hazardous metal responsible for environmental contamination and human intoxication. Methylmercury, a very toxic organic compound, bio-accumulates through food chain, and is responsible for chronic mercury exposure of riverside Amazonian communities with a diet rich in fish. Uncertainties about the reference exposure dose that could have damaging consequences for nervous system development makes necessary the biomonitoring of these Amazonian populations, especially children. In this work, a comparative study was performed in exposed and non-exposed children living in the Amazon. A total of 168 children were analyzed to find possible correlations between gender, age, location, and hair mercury content. For each location, no statistically significant differences (P<0.05) were detected for gender and age versus mercury content. However, mean mercury levels in hair samples may indicate a tendency of boys to average higher hair concentrations. Also, in the community with highest levels of mercury, the limit of 10 micro g/g of mercury was surpassed by 65% of 2-6 years and 50% of 7-12 years children but only by 27% of 0-1 year babies, pointing to a lower bioaccumulation and/or the existence of a protection mechanism in babies. Log normal distributions of mercury concentrations for each location showed that children from populations under influence of gold mining activity contain the highest mercury levels in hair samples, though this intoxication may have decreased when compared to previous studies. Knowledge originated by this monitoring will better assist in the development of prevention strategies and government actions targeting the mercury contamination of Amazonian environment.     

Visual diagnosis of solid waste contamination of a tourist beach: Pernambuco, Brazil

The solid waste accumulation patterns on Tamandaré beach, Pernambuco State (Brazil), was assessed from February 2001 to July 2002. This beach is easily accessible, frequently used, and there is a public cleaning service. The beach is under the influence of three small coastal drainage basins. The study visually divided the beach into 15 segments according to the level of solid waste contamination into absent (A), trace (B), unacceptable (C) and objectionable (D). The lowest levels of contamination were found at the middle part of the study area, the most vulnerable in respect to coastal erosion presenting numerous interventions on the beach, absence of native vegetation and lesser width. The highest levels of contamination were at the northern and southern ends of the area, where there are no developments, the beach morphology favours deposition of sediments, there is native vegetation and the beach is wider. The D level did not occur within the area.     

Conservation Priorities and Population Structure of Woody Medicinal Plants in an Area of <Emphasis Type="Italic">Caatinga</Emphasis> Vegetation (Pernambuco State,NE Brazil)

In spite of heavy harvesting pressure on some of the most popular medicinal plant species, there are very few published studies concerning their conservation the semi-arid region of northeastern Brazil. In light of this fact, the present work sought to evaluate the local conservation and the harvesting sustainability of medicinal plants in an region of caatinga vegetation employing a fusion of biological and cultural approaches. Ethnobotanical methodologies and techniques were employed in the community of “Riachão de “Malhada de Pedra”” (municipality of Caruaru, state of Pernambuco, Brazil) in order to document local knowledge concerning medicinal plants and to examine the availability of those plants in a caatinga vegetation fragment located near that community. A total of 21 medicinal plant species were identified in the area and classified according to ecological factors and local uses. Two plants (Ziziphus joazeiro and Myracrodruon urundeuva) stood out has having high priority for conservation efforts. Sixteen species were identified as having populations adequate for harvesting through a system of pre-determined quotas, while four species were deemed sufficiently abundant to be harvested without risk of causing significant impact on their sustainability.