Solid‐phase extraction and GC analyses of select agricultural pesticides and metabolites in stream water

Abstract

The occurrence of agricultural pesticides in surface waters around the USA has created a concern over the status of safe drinking water. Solid‐phase extraction (SPE) or liquid‐liquid extraction (LLE) is usually employed to concentrate trace levels of pesticides in water samples to concentrations that are measurable with advanced chromatographic instruments. We describe here a SPE and capillary gas chromatographic (GC) procedure to extract and concentrate trace levels of select agricultural pesticides and metabolites from stream water. Our SPE and GC method provides high sensitivity, with recoveries between 85% to 95%, and high reproducibility for 9 of the pesticides studied. The described method provided marginal recoveries of 19 and 60% for the atrazine metabolites.     

Investigations into the differential reactivity of endogenous and exogenous mercury species in coastal sediments

Stable isotopic tracer methodologies now allow the evaluation of the reactivity of the endogenous (ambient) and exogenous (added) Hg to further predict the potential effect of Hg inputs in ecosystems. The differential reactivity of endogenous and exogenous Hg was compared in superficial sediments collected in a coastal lagoon (Arcachon Bay) and in an estuary (Adour River) from the Bay of Biscay (SW France). All Hg species (gaseous, aqueous, and solid fraction) and ancillary data were measured during time course slurry experiments under variable redox conditions. The average endogenous methylation yield was higher in the estuarine (1.2 %) than in the lagoonal sediment (0.5 %), although both methylation and demethylation rates were higher in the lagoonal sediment in relation with a higher sulfate-reducing activity. Demethylation was overall more consistent than methylation in both sediments. The endogenous and exogenous Hg behaviors were always correlated but the exogenous inorganic Hg (IHg) partitioning into water was 2.0–4.3 times higher than the endogenous one. Its methylation was just slightly higher (1.4) in the estuarine sediment while the difference in the lagoonal sediment was much larger (3.6). The relative endogenous and exogenous methylation yields were not correlated to IHg partitioning, demonstrating that the bioavailable species distributions were different for the two IHg pools. In both sediments, the exogenous IHg partitioning equaled the endogenous one within a week, while its higher methylation lasted for months. Such results provide an original assessment approach to compare coastal sediment response to Hg inputs.     

Evaluation of landfill leachate treatment by advanced oxidative process by Fenton’s reagent combined with membrane separation system

A high content of refractory organic matter, ammonia and toxic compounds is characteristic of landfill leachate. Advanced oxidative processes (AOPs) are an attractive alternative for landfill leachate treatment. However, when applied as a unique process treatment, they do not provide a complete solution for the effluent treatment. Combining AOP with a membrane separation process (MSP) presents a number of benefits and provides an adequate solution for this problem. With this in mind, the present work aims to evaluate, using a bench scale, leachate treatability through AOP by Fenton’s reagent (AOP/Fenton) combined with microfiltration (MF) and nanofiltration (NF). A high efficient removal of COD (63%), true color (76%) and humic substances (50%) was observed during AOP/Fenton under optimized conditions (1.7 g H₂O₂/g COD_{raw leachate}; FeSO₄·7H₂O:H₂O₂ = 1:5.3; pH = 3.8; reaction conditions = 115 rpm/28 min). According to the evaluated parameters, MSP presented an efficient complementary treatment, in which the integrity of the stages was sufficient for reaching regulatory levels in the effluent (Deliberação Normativa Conjunta COPAM/CERH-MG N^o. 1, May 5, 2008).     

δ 13C and δ 15N variations in organic matter pools, Mytilus spp. and Macoma balthica along the European Atlantic coast

Stable carbon (δ ¹³C) and nitrogen (δ ¹⁵N) isotope (SI) values of sedimentary organic matter (SOM), seston and two dominant bivalves, Mytilus spp. and Macoma balthica, were studied at 18 stations along the European coast in spring and autumn 2004. Three main regions, the Baltic Sea (BS), the North Sea and English Channel (NS), and the Bay of Biscay (BB), were tested for possible geographic (latitudinal) differences in the SI values. In spring, only BS showed lower δ ¹³C values of seston and Mytilus spp., and higher δ ¹⁵N values of SOM, than NS and BB. No significant differences between the 3 regions were found in autumn. Irrespective of season and regions, Mytilus spp. was more ¹³C-depleted than M. balthica. δ ¹³C values of M. balthica, but not those of Mytilus spp., were significantly correlated with SOM. These results are consistent with differences in feeding behavior of Mytilus spp. and M. balthica, as the two species are known as obligatory-suspension and facultative-deposit feeders, respectively. In contrast, no differences in the δ ¹⁵N values of Mytilus spp. and M. balthica were found at individual stations, indicating the same trophic level of the two bivalves within the food webs. At some stations, irrespective of geographic location, both bivalves showed δ ¹⁵N values up to 18–20 ‰. These were two trophic levels higher than those found at the other stations, indicating local and/or episodic eutrophic conditions, probably due to waste water discharge, and the effectiveness of both Mytilus spp. and M. balthica as bio-indicators of anthropogenic eutrophication. Overall, our results suggest that pathways of energy flow from OM pools to dominant bivalves is more related to local environmental conditions than to geographic regions across the European coastline. This has implications for food web studies along the Atlantic coast because most of the values are consistent over a large area and show no significant differences. Therefore, the present study can be used twofold for the determination of trophic baselines and for the correction of the trophic position of consumers higher up in the food web in the case of differences in waste water discharge.     

Toxic effects of carbofuran and glyphosate on semen characteristics in rabbits

Abstract

The present study was undertaken to investigate the effect of chronic treatment with two sublethal doses of Carbofuran (carbamate insecticide) and Glyphosate (organophosphorus herbicide) on body weight and semen characteristics in mature male New Zealand white rabbits. Pesticide treatment resulted in a decline in body weight, libido, ejaculate volume, sperm concentration, semen initial fructose and semen osmolality. This was accompanied with increases in the abnormal and dead sperm and semen methylene blue reduction time. The hazardous effect of these pesticides on semen quality continued during the recovery period, and was dose‐dependent. These effects on sperm quality may be due to the direct cytotoxic effects of these pesticides on spermatogenesis and/or indirectly via hypothalami‐pituitary‐testis axis which control the reproductive efficiency.     

Nanoscale materials and their use in water contaminants removal—a review

Water scarcity is being recognized as a present and future threat to human activity and as a consequence water purification technologies are gaining major attention worldwide. Nanotechnology has many successful applications in different fields but recently its application for water and wastewater treatment has emerged as a fast-developing, promising area. This review highlights the recent advances on the development of nanoscale materials and processes for treatment of surface water, groundwater and industrial wastewater that are contaminated by toxic metals, organic and inorganic compounds, bacteria and viruses. In addition, the toxic potential of engineered nanomaterials for human health and the environment will also be discussed.     

The Formulation of Emission Control Strategies Using a Cubic Polynomial Approximation

Assuming the existence of an ambient air standard for a given pollutant, there is some agreement that emission standards for local area and point sources should be established by formulating and testing various “control strategies” with use of a computer diffusion model. The procedure requires several, perhaps many, computer simulations of pollutant dispersion followed by an analysis of the results of each simulation. Part of this analysis is to include an “optimization” of sorts which is intended to provide a workable control strategy which, in turn, is to indicate required emission level reductions for point sources. This paper is intended to describe and apply an approximation technique which, when used in conjunction with a diffusion model, could be of value in determining acceptable emission levels for point sources.     

Methylcyclopentadienyl Manganese Tricarbonyl as an Antiknock: Composition and Fate of Manganese Exhaust Products

Methylcyclopentadienyl manganese tricarbonyl (MMT) has been marketed as a combustion improver for fuel oil and turbine fuel. Use concentrations for this purpose are about 0.025 g manganese/gal in fuel oil and 0.08 to 0.5 g/gal in turbine fuels. In addition, it has been used to a small extent in gasoline.     

The survival strategy of Crepis tectorum L. under conditions of chronic atmospheric pollution

The results of demographic studies on Crepis tectorum L. populations from polluted and clean habitats are presented. They show that these populations significantly differ from each other in a number of parameters, including the seasonal dynamics of seed germination, the number of generations, the time of plant transition to reproduction, and the rate of generation succession in general. These data provide evidence that populations of annual or biennial plants can employ different survival strategies when growing under conditions of pollution or its absence.     

A procedure to design a Permeable Adsorptive Barrier (PAB) for contaminated groundwater remediation

A procedure to optimize the design of a Permeable Adsorptive Barrier (PAB) for the remediation of a contaminated aquifer is presented in this paper. A computer code, including different routines that describe the groundwater contaminant transport and the pollutant capture by adsorption in unsteady conditions over the barrier solid surface, has been developed. The complete characterization of the chemical–physical interactions between adsorbing solids and the contaminated water, required by the computer code, has been obtained by experimental measurements. A case study in which the procedure developed has been applied to a tetrachloroethylene (PCE)-contaminated aquifer near a solid waste landfill, in the district of Napoli (Italy), is also presented and the main dimensions of the barrier (length and width) have been evaluated. Model results show that PAB is effective for the remediation of a PCE-contaminated aquifer, since the concentration of PCE flowing out of the barrier is everywhere always lower than the concentration limit provided for in the Italian regulations on groundwater quality.