Simultaneous determination of parathion and p-nitrophenol in vegetable tissues by derivative spectrophotometry

A first derivative spectrophotometric method has been developedfor the determination of parathion and p-nitrophenol in vegetabletissues. Ethanol was used as solvent for extracting the compoundsfrom the tissues and subsequently the samples were evaluated against a vegetable tissue blank, directly by derivative spectrophotometry. The simultaneous determination of these compounds can be carried out using the zero-crossing approach for parathion at 253.0 nm and for p-nitrophenol at 273.1 nm. In the samples each analyte was determined in the presence of one another in the ranges between 4.9 to 3883.5 g g^-1 forparathion and 4.9 to 3285.3 g g^-1 for p-nitrophenol.The detection limits (3) were found to be 1.5 and 1.4 g g^-1 for parathion and p-nitrophenol, respectively. The relative standard deviations were in all instances less than1.8%. The proposed method was applied to the determination ofthe analytes in spiked leafs of corn. The results show a goodrecovery and they are in agreement with those obtained bypolarography.     

Threats to intact tropical peatlands and opportunities for their conservation

Large, intact areas of tropical peatland are highly threatened at a global scale by the expansion of commercial agriculture and other forms of economic development. Conserving peatlands on a landscape scale, with their hydrology intact, is of international conservation importance to preserve their distinctive biodiversity and ecosystem services and maintain their resilience to future environmental change. We explored threats to and opportunities for conserving remaining intact tropical peatlands; thus, we excluded peatlands of Indonesia and Malaysia, where extensive deforestation, drainage, and conversion to plantations means conservation in this region can protect only small fragments of the original ecosystem. We focused on a case study, the Pastaza‐Marañón Foreland Basin (PMFB) in Peru, which is among the largest known intact tropical peatland landscapes in the world and is representative of peatland vulnerability. Maintenance of the hydrological conditions critical for carbon storage and ecosystem function of peatlands is, in the PMFB, primarily threatened by expansion of commercial agriculture linked to new transport infrastructure that is facilitating access to remote areas. There remain opportunities in the PMFB and elsewhere to develop alternative, more sustainable land‐use practices. Although some of the peatlands in the PMFB fall within existing legally protected areas, this protection does not include the most carbon‐dense (domed pole forest) areas. New carbon‐based conservation instruments (e.g., REDD+, Green Climate Fund), developing markets for sustainable peatland products, transferring land title to local communities, and expanding protected areas offer pathways to increased protection for intact tropical peatlands in Amazonia and elsewhere, such as those in New Guinea and Central Africa which remain, for the moment, broadly beyond the frontier of commercial development.     

Assessment of the Streptomyces-plant system to mitigate the impact of Cr(VI) and lindane in experimental soils

Environmental Science and Pollution Research - Phytoremediation techniques have been proposed as ecological methods to clean up contaminated sites. This study is aimed to evaluate the effect of the...     

Use of beryllium-7 to document soil redistribution following forest harvest operations

Rapid and reliable methods for documenting soil erosion associated with forest harvest operations are needed to support the development of best management practices for soil and water conservation. To address this need, the potential for using 7Be measurements to estimate patterns and amounts of soil redistribution associated with individual post-harvest events was explored. The 7Be technique, which was originally developed for use on agricultural land, was employed to estimate soil redistribution associated with a period of heavy rainfall within a harvested forest area located in the Lake Region of Chile (39 degrees 44'7' S, 73 degrees 10'39' W; 22% slope; and mean annual rainfall 2300 mm yr(-1)). The results provided by the 7Be technique were validated against direct measurements of soil gain or loss during the same period obtained using erosion pins. The information produced by the two approaches was similar. The results of this study demonstrate the potential for using 7Be measurements to document event-based erosion in recently harvested forest areas.     

Landfill leachate treatment using a rotating biological contactor and an upward-flow anaerobic sludge bed reactor

This paper describes the feasibility of an aerobic system (rotating biological contactor, RBC) and a biological anaerobic system (upward-flow anaerobic sludge bed reactor) at small scale for the treatment of a landfill leachate. In the first phase of the aerobic system study, a cyclic-batch RBC system was used to select perforated acetate discs among three different acetate disc configurations. These discs were chosen on the basis of high COD removal (65%) and biological stability. In the second phase, the RBC system (using four stages) was operated continuously at different hydraulic retention times (HRT), at different rotational speeds, and with varying organic concentrations of the influent leachate (2500-9000mgL(-1)). Forty percent of the total surface area of each perforated disc was submerged in the leachate. A COD removal of about 52% was obtained at an HRT of 24h and a rotational speed of 6rpm. For the anaerobic system, the reactor was evaluated with a volumetric organic load of 3273g-COD m(-3) day(-1) at an HRT of 54, 44, 39, 24 and 17h. At these conditions, the system reached COD removal efficiencies of 62%, 61%, 59%, 44% and 24%, respectively.     

Effect of a reservoir in the water quality of the Reconquista River, Buenos Aires, Argentina

The lower portion of the Reconquista River is highly polluted. However, little is known about the state of the high and middle basins. The aims of this work were to assess the water quality on the high and middle Reconquista River basins and to determinate if the presence of a reservoir in the river has a positive effect on the water quality. We conducted a seasonal study between August 2009 and November 2010 at the mouth of La Choza, Durazno, and La Horqueta streams at the Roggero reservoir—which receives the water from the former streams—at the origin of the Reconquista River and 17 km downstream from the reservoir. We measured 25 physical and chemical parameters, including six heavy metal concentrations, and performed a multivariate statistical analysis to summarize the information and allow the interpretation of the whole data set. We found that the Durazno and La Horqueta streams had better water quality than La Choza, and the presence of the reservoir contributed to the improvement of the water quality, allowing oxygenation of the water body and processing of organic matter and ammonia. The water quality of the Reconquista River at its origin is good and similar to the reservoir, but a few kilometers downstream, the water quality declines as a consequence of the presence of industries and human settlements. Therefore, the Roggero reservoir produces a significant improvement of water quality of the river, but the discharge of contaminants downstream quickly reverses this effect.     

Assessment of commercially available polymeric materials for sorptive microextraction of priority and emerging nonpolar organic pollutants in environmental water samples

Among the different organic pollutants, persistent organic pollutants and emerging organic contaminants (EOCs) are of particular concern due to their potentially dangerous effects on the ecosystems and on human health. In the framework of the analysis of some of these organic pollutants in water samples, sorptive extraction devices have proven to be adequate for their monitoring. The efficiency of four commercially available and low-cost polymeric materials [polypropylene, poly(ethylene terephthalate), Raffia, and polyethersulfone (PES)] for the simultaneous extraction of 16 organic compounds from five different families from environmental water samples was evaluated in this work. Firstly, the homogeneity of the sorbent materials was confirmed by means of Raman spectroscopy. After the optimization of the parameters affecting the extraction and the liquid desorption steps, it was found that PES showed the largest efficiencies for slightly polar analytes and, to a lesser extent, for nonpolar analytes. Additionally, Raffia rendered good extraction efficiencies for nonpolar compounds. Thus sorptive extraction methods followed by large volume injection-programmable temperature vaporizer-gas chromatography-mass spectrometry were validated using PES and Raffia as sorbent materials. The validation of the method provided good linearity (0.978?r ²?r ²?-1 level). Finally, these materials were applied to the analysis of contaminants in environmental water samples.     

Structural changes in soil communities after triclopyr application in soils invaded by Acacia dealbata Link

Triclopyr is a commonly used herbicide in the control of woody plants and can exhibit toxic effects to soil microorganisms. However, the impact on soils invaded by plant exotics has not yet been addressed. Here, we present the results of an 18-month field study conducted to evaluate the impact of triclopyr on the structure of fungal and bacterial communities in soils invaded by Acacia dealbata Link, through the use of denature gradient gel electrophoresis. After triclopyr application, analyses of bacterial fingerprints suggested a change in the structure of the soil bacterial community, whereas the structure of the soil fungal community remained unaltered. Bacterial density and F:B ratio values changed across the year but were not altered due to herbicide spraying. On the contrary, fungal diversity was increased in plots sprayed with triclopyr 5 months after the first application. Richness and diversity (H´) of both bacteria and fungi were not modified after triclopyr application.     

Speciation of Arsenic in Ambient Aerosols Collected in Los Angeles

First-time measurements of the potentially toxic inorganic species of arsenic (arsenite arid arsenate) have been obtained in fine (<2.5 µm AD) and coarse (>2.5 µm AD) atmospheric particles in the Los Angeles area. A recently developed method that includes procedures for sample collection, preparation, and analysis was used in this study. Size-fractlonated aerosol samples were collected with a high-volume dichotomous virtual impactor that employed polytetrafluoroethylene filters. Results were obtained for the recovery of arsenic standards added to unexposed and collected filters. Data from this study, indicated that the recently developed speciation method can be used to determine concentrations of As(lll) and As(V) In atmospheric particulate matter samples.

Size-fractionated aerosol samples were collected in the city of Industry during January and February 1987. In most samples, As(lll) and As( V) were above the detection limit (approximately 1 ng m^-3 of either species) in both aerosol size fractions. A greater portion (about 75 percent) of the two species were observed in the fine particles. The As(lll)/As(V) ratio for both particle sizes was close to 1 (I.e., an equal mixture of both species). Comparison of total suspended particulate arsenic measured by the speciation method to that measured by a routine California Air Resources Board-approved procedure showed good agreement (r = 0.94), indicating both methods were approximately equivalent for the collection and analysis of aerosol arsenic.     

Potential of acid activated clays in the clarification of menhaden stickwater

Abstract

The primary objective of this investigation was to determine the feasibility of using acid activated clays to clarify menhaden stickwater effluent. Experiments, such as physical and chemical properties determinations, effect of changes in pH and temperature and coagulation, and coagulation followed by clay treatment were also performed to study the separation of solids in stickwater.

Analysis of the stickwater showed that it contained 4.5% crude protein, 1.4% crude fat, 6.5% total solids, 1.13% ash and 93.1% water. At a wavelength of 575 um, the sample absorbed all the light and the percent transmittance was zero. When diluted 1:100 the percent transmittance was 0.39 at the same wavelength. Measured at 25°C the sample had a viscosity of 9.0 centipoises.

The results showed that the precipitation of fat increased with increasing temperatures, while the reverse was true for protein. A pH of 4.0 gave the maximum clarification at all temperatures employed. The viscosity decreased at pH values above and below the original pH of the sample.

Among the four different acid activated clays used in this study (trade names Supact‐150, Impact‐150, Impact‐12 and Impact‐1OORR), Impact‐150 was the most effective in protein and fat precipitation, and the degree of separation of these components increased by treating stickwater with a coagulant (aluminum sulfate) prior to treatment with acid activated clay.