Anatomical element localization by EDXS in Grevillea exul var. exul under nickel stress

Grevillea exul var. exul, an endemic serpentinic Proteaceae of New Caledonia, was chosen to study the spatial distribution of Ni because this species supports strong content of metals, which can allow important absorptions thus detectable by microanalysis. Fine transversal sections of axenic G. exul var. exul plants grown during 15 days on nickel sulphate medium were examined by EDXS microanalysis. It showed that in Ni treated plants, Ni was concentrated mostly in the phloem compared to the xylem and the epidermis, either in roots or in the basal part of the stems and was mostly in the epidermis in the upper part of the stems and not detectable in the leaves. This metal took the place of P and K in the treated plants whereas the localization of these macroelements was quite uniform in control sections. We assume that a mechanism of phloem loading is implicated to restrict Ni accumulation in G. exul var. exul.     

In field arsenic removal from natural water by zero-valent iron assisted by solar radiation

An in situ arsenic removal method applicable to highly contaminated water is presented. The method is based in the use of steel wool, lemon juice and solar radiation. The method was evaluated using water from the Camarones River, Atacama Desert in northern Chile, in which the arsenic concentration ranges between 1000 and 1300 μg L⁻¹. Response surface method analysis was used to optimize the amount of zero-valent iron (steel wool) and the citrate concentration (lemon juice) to be used. The optimal conditions when using solar radiation to remove arsenic from natural water from the Camarones river are: 1.3 g L⁻¹ of steel wool and one drop (ca. 0.04 mL) of lemon juice. Under these conditions, removal percentages are higher than 99.5% and the final arsenic concentration is below 10 μg L⁻¹. This highly effective arsenic removal method is easy to use and inexpensive to implement.     

Contribution of Spartina maritima to the reduction of eutrophication in estuarine systems

Salt marshes are among the most productive ecosystems in the world, performing important ecosystem functions, particularly nutrient recycling. In this study, a comparison is made between Mondego and Tagus estuaries in relation to the role of Spartina maritima in nitrogen retention capacity and cycling. Two mono-specific S. maritima stands per estuary were studied during 1 yr (biomass, nitrogen (N) pools, litter production, decomposition rates). Results showed that the oldest Tagus salt marsh population presented higher annual belowground biomass and N productions, and a slower decomposition rate for litter, contributing to the higher N accumulation in the sediment, whereas S. maritima younger marshes had higher aboveground biomass production. Detritus moved by tides represented a huge amount of aboveground production, probably significant when considering the N balance of these salt marshes. Results reinforce the functions of salt marshes as contributing to a reduction of eutrophication in transitional waters, namely through sedimentation processes.     

Biochemical effects of clomazone herbicide on piava (Leporinus obtusidens)

This study aims to verify the effects of the clomazone concentration used in rice fields on acetylcholinesterase (AChE), thiobarbituric acid reactive substances (TBARS), protein carbonyl and catalase activity in tissues of piava (Leporinus obtusidens). LC(50)-96h was 5.0 mg L(-1) and the fish were exposed to 1/10 of LC(50)-96 h: 0.5 mg L(-1) of clomazone for 96 and 192h. The same parameters were also assayed after a recovery period of 192 h in clean water. AChE activity was reduced only in the brain and heart of fish exposed for 96 h. AChE activity was decreased in the brain, muscle and heart tissues after 192 h of exposure. After 192 h of recovery period, AChE activity remained diminished in brain and muscle and showed a decrease in eye. However, after 192 h of recovery, AChE activity in heart was recovered. Fish showed increased TBARS levels in brain at all experimental periods. TBARS levels decreased in liver and muscle tissues after 192 h of exposure. The increase in muscle TBARS persisted in fish transferred to clean water. Protein carbonyl in the liver was increased in all periods studied including the recovery period. Catalase activity was reduced during all periods. The present study demonstrates the occurrence of disorders in AChE, TBARS, protein carbonyl and catalase activity in piava. The results also show changes in fish after exposure to an environmentally relevant concentration of clomazone. Most effects observed persisted after the recovery period. Thus, these parameters may be used to monitor clomazone toxicity in fish.     

Sorption of fenamiphos to different soils: the influence of soil properties

Fenamiphos (0-ethyl-0(3-methyl-4-methylthiophenyl)-isopropylamido-phosphate) is a widely used nematicide and insecticide in bowling greens and agriculture, but information on its sorption including its metabolites is limited. Hence, the sorption of fenamiphos (nematicide) and its major degradation products fenamiphos sulfoxide (FSO) and fenamiphos sulfone (FSO2) were determined in thirteen contrasting soils collected from Australia and Ecuador. The sorption coefficients (Kd) exhibited a wide range of variation from 2.48 to 14.94 L/Kg for fenamiphos; from 0 to 7.42 L/Kg for FSO and from 0 to 9.49 L/Kg for FSO2. The sorption affinity of the three compounds for all soils tested was as follows: fenamiphos > fenamiphos sulfone > fenamiphos sulfoxide. The results showed that the sorption of fenamiphos and its metabolites in some soils is very low, and in one case is nonexistant for the metabolites. This is of particular concern as due to its low sorption coefficient, the compound could easily migrate and contaminate water bodies. Fenamiphos and its oxidation products have been reported to be highly toxic to aquatic invertebrates and therefore, the information generated in this study assumes great importance in the risk assessment of fenamiphos and its metabolites in the environment.     

Photochemical degradation of methylparathion in the presence of humic acid

Photochemical degradation of methylparathion (O,O,-dimethyl O-4 nitrophenylphosphorothioate) in the presence of humic acid between pH 2 and 7 was monitored by differential pulse polarography. Humic acid was not electro-active under the experimental conditions used in this study. Only the pesticide and its main degradation product at pH 2 exhibited polarographic signals. Photolysis of methylparathion in acid media was sensitized by humic acid since the pesticide did not degrade in the absence of this compound. Methylparathion degradation in the presence of humic acid was observed at each of the studied pHs. The reaction was first-order with rate constant values ranging from 2 x 10(-3) to 6.3 x 10(-3) min(-1).     

Increased thyroid volume, prevalence of thyroid antibodies and impaired fasting glucose in young adults from organochlorine cocktail polluted area: outcome of transgenerational transmission?

In 137 females (F) and 94 males (M) aged 21-35 years from organochlorines (OCs) polluted area (POLL) increased thyroid volume (ThV), prevalence of antibodies to thyroperoxidase (TPOab), thyrotropin receptor (TRab) and of impaired fasting glucose (IFG) was found compared to 116 F and 107 M from background pollution area (BCGR). In F and M from POLL also strikingly increased level of PCBs, DDE and HCB was found. Such findings were compared to the generation of their parents aged 41-55 years consisting of 320F/213M from POLL and 406F/231M from BCGR. However, in spite of strikingly lower level of those OCs in young adults from POLL, they showed about the same prevalence of adverse health signs as the old generation. From such reason 44 young F and 40 young M with lowest PCBs level from POLL were selected to obtain nearly the same PCB level as found in all young F and M from BCGR. In such PCB adjusted groups the prevalence of TPOab, TRab, IFG and increased ThV was still significantly higher than that in all young subjects from BCGR. At the same time, also the level of DDE and HCB in such PCBs adjusted groups was considerably lower. It was concluded that such adverse effects in young adults from POLL possibly did not result from their actual OCs levels, but very likely from their exposure to high OCs levels of their mothers during their prenatal and perinatal life. Thus, the data may be compatible with present views on transgenerational transmission of endocrine disruptors action.     

Hepatic monooxygenase (CYP1A and CYP3A) and UDPGT enzymatic activities as biomarkers for long-term carbofuran exposure in tench (Tinca tinca L)

The effect of a long-term exposure of tenchs to different concentrations (10 and 100 micro g/L) of the pesticide carbofuran has been evaluated. Microsomal hepatic cytochrome P450 subfamily 1A (CYP1A) and 3A (CYP3A) activities, as well as the phase II enzyme uridine diphospho-glucuronosyltransferase (UDPGT) activity were evaluated as adequate biomarkers of fish exposure to environmentally relevant concentrations of the pesticide carbofuran in freshwater ecosystems. A clear time-dependent inhibition of both CYP1A and UDPGT activities was observed in fish exposed to the highest dose of carbofuran with respect to controls, whereas in the case of CYP3A activity, values of exposed animals did not show a clear pattern of alteration during the experiment. The results of the present study demonstrated that hepatic CYP1A and UDPGT activities from tench could be considered as sensitive biomarkers for carbamate pesticides in polluted water, thus allowing future and ecologically relevant biomonitoring studies with this species.