Emília Silva

Pesticides and nitrates in groundwater from oriziculture areas of the ‘Baixo Sado’ region (Portugal)

The aim of this study was the groundwater evaluation to pesticide compounds and nitrates in oriziculture areas of the ‘Baixo Sado’ region (Portugal), based on their use, predictive approaches, and field and laboratory work. One or more of the pesticide compounds analysed (chlorfenvinphos, cycloxydim, 3,4-dichloroaniline, endosulphan, MCPA, molinate, oxadiazon, profoxydim, propanil) were detected in 62% of 171 water samples collected from 22 wells used for public supply, domestic supply, and irrigation, during 2002 and 2003. From the total samples, 6% presented maximum concentration levels of at least one of the compounds above 0.1 µg L−1. Mixtures of pesticide compounds were observed in 25% of the total groundwater samples, with up to five substances being detected in each one. The concentration sum of all was above 0.5 µg L−1 in four water samples. All the analysed compounds, with the exception of the insecticide chlorfenvinphos, occurred in groundwater. Molinate was the most frequently detected (55%), particularly with maximum concentration levels above 0.1 µg L−1. Detection frequencies were higher in water samples collected from irrigation wells (78%). Groundwater exposure to total pesticides and nitrates was analysed. Maximum concentration levels were 59.6 µg L−1 and 183 mg L−1 respectively. A seasonal variation pattern could be observed for both parameters in water samples collected from some wells. The results from this study show that sustainable use of pesticides and nitrogen fertilizers is required in order to achieve an overall contamination reduction from these compounds in the aquatic environment.

Environmental Fate of Neonicotinoids and Classification of Their Potential Risks to Hypogean, Epygean, and Surface Water Ecosystems in Brazil

ABSTRACT Due to their reported high toxicity to honey bees, ecotoxicological studies into the side-effects of neonicotinoid insecticides have focused almost exclusively on these organisms. The fate of neonicotinoids and potential toxic side-effects on other (especially non-standard) organisms have received considerably less attention. In the present study, the environmental distribution and leaching potential of neonicotinoids registered for agricultural use in Brazil (acetamiprid, clothianidin, imidacloprid, thiacloprid, and thiamethoxam) were studied by applying several environmental fate models and indices. Potential risks to various environmental compartments were evaluated by applying ranking indices to the maximum application rates recommended in Brazil. Although bees were indeed found to be the most sensitive organism, the neonicotinoids also indicated potential environmental risks to other organism groups. Due to the greater maximum application rates recommended in Brazil as compared to other parts of the world, environmental risk and resistance potential for at least imidacloprid appears especially high in Brazil. Attention should thus also be allocated to organisms other than bees and to resistance potential when performing an environmental risk assessment of neonicotinoids if they are used at relatively high application rates.

Preliminary aquatic risk assessment of imidacloprid after application in an experimental rice plot

The potential aquatic risk of application of the neonicotinoid insecticide imidacloprid for aphid control in rice was assessed. To this end, imidacloprid was applied as Confidor(®) 200 SC at the recommended field dose of 100g a.i./ha to a Portuguese rice plot. Subsequently, fate of the test compound in water and potential effects of water samples on a battery of test species were determined. As compared to the first-tier predicted environmental concentrations (PECs) calculated using MED-Rice (around 30µg/L depending on the scenario used) and US-EPA (78µg/L) simulations, the actual peak concentration measured in the paddy water (52µg/L) was higher and lower, respectively. As was anticipated based on 50% effect concentrations (EC50 values) for Daphnia magna published in the open literature and that calculated in the present study (48h-EC50 immobility=84mg/L), no effects were observed of field water samples on daphnids. The sediment-dwelling ostracod Heterocypris incongruens, however, appeared relatively sensitive towards imidacloprid (6d-EC50 growth inhibition=0.01-0.015mg/L) and a slight effect was indeed noted in field samples taken the first week after application. Species sensitivity distributions based on published EC50 and NOEC values also revealed that other species are likely to be affected at the peak and time-weighted average imidacloprid concentrations, respectively. By applying the relative tolerance approach (i.e. by dividing the EC50 value of a certain species with that of Daphnia magna), ostracods appear to contain the most sensitive taxa to imidacloprid, followed by EPT (Ephemeroptera, Plecoptera and Trichoptera) taxa. Future field studies into (higher-tier) fate modelling of pesticides in rice paddies and effect assessment on field communities are required to ensure protection of aquatic life and wildlife (e.g. birds) from pesticide stress.

Assessing the quality of freshwaters in a protected area within the Tagus River basin district (central Portugal).

Water-sediment quality was assessed in an agricultural zone of a protected area within the Tagus River basin district (central Portugal) combining chemical analysis to 12 pesticide compounds and whole toxicity testing using the bacterium , the algae , the crustacean , and the midge . The herbicides alachlor, atrazine ethofumesate, metolachlor, terbuthylazine, the insecticides chlorfenvinphos and chlorpyrifos, and the metabolite 3,4-dichloroaniline were detected in surface water samples at four sites and in groundwater samples from six wells, during four sampling occasions. Measured concentrations were compared with parametric values for human consumption, groundwater quality standards, and environmental quality standards applicable to surface water established in European Union legislation. Most severe adverse effects were noted on the growth of and lethality of in nondiluted water samples. Taking into account the values calculated by the method of toxic unit summation for pesticide mixtures, it was not possible to link the pesticides found to the toxicity detected in the water samples. Conducting this study with chemical analyses and biotests provided a more comprehensive quality assessment and realistic picture of the environmental samples analyzed, although additional studies are needed to evaluate the performance of mixture models for predicting mixture toxicity. This study underlines the importance of chemical analysis and whole toxicity testing as tools for assessing the impact of human activity on the status of water, mainly in protected zones.

Exposure of ground water to alachlor, atrazine and metolachlor in maize areas of ribatejo and oeste (Portugal)

In irrigated maize areas of an important Portuguese agricultural area, Ribatejo and Oeste Region, alachlor, atrazine and metolachlor were detected in ground water. During the study performed from 1996 to 1998 atrazine was the herbicide that showed the highest frequency of detection. In the 177 ground water samples collected 62% were contaminated with atrazine, 30% with alachlor and 12% with metolachlor. All these herbicides were detected both in ground water for human consumption and for irrigation, in some cases above 0.1 ug/L. The maximum levels quantified were 13μg/L for alachlor, 30μg/L for atrazine and 56 μg/L for metolachlor. Seasonal variation of residues in ground water it is also presented through several examples of studies performed during the period 1991–1999.

Does the actual standard of 0.1 μg/L overestimate or underestimate the risk of plant protection products to groundwater ecosystems?

The present groundwater standard of 0.1 microg/L for plant protection products (PPPs) has been under much debate because an ecotoxicological base is missing. In the present study, groundwater threshold values were calculated for all PPPs currently included in Annex I to Directive 91/414/EEC using three different approaches: (1) first-tier (Daphnia magna and Vibrio fisheri); (2) species sensitivity distributions, constructed for surrogate freshwater organisms for the truncated groundwater biodiversity; (3) the case-based model PERPEST. For the majority of the PPPs, the trigger value of 0.1 microg/L appears to be sufficiently protective. However, it may not fully protect groundwater life from several insecticides. Implications for the environmental risk assessment of groundwater and recommendations for future research are discussed.

Applicability of the New 60 µm Polyethylene Glycol Solid-Phase Microextraction Fiber Assembly for the Simultaneous Analysis of Six Pesticides in Water

A solid-phase microextraction (SPME) method has been applied for the simultaneous analysis of six pesticides in water, with polar to moderately polar range, by gas chromatography-mass spectrometry (GC-MS). Two types of fiber coatings [60 µm polyethylene glycol (PEG) and 65 µm polydimethylsiloxane/divinylbenzene (PDMS/DVB)] and the effect of salt (addition of 10 and 25% of NaCl) were compared. The extraction efficiency was higher with PEG than with the PDMS/DVB fiber for all pesticides, with the exception of terbuthylazine and phosmet, and with addition of 25% NaCl. The optimized SPME-GC-MS method, adopting the PEG fiber and the addition of 25% NaCl, in addition to other conditions [60 min of direct dipping of the fiber into the water sample (10 mL) under agitation (250 rpm) at ambient temperature; desorption period of 5 min at 240°C] allowed the determination of all studied pesticides and showed good linearity for concentrations ranging from 0.05 to 5 µg/L. Limits of detection varied between 0.003 and 0.145 µg/L, with values below 0.025 µg/L for most of the analytes. Precision ranged from 4.2 to 12%. The proposed method is fast and simple, and was proven to be reliable for the routine analysis of pesticides in water, primarily for environmental monitoring.

Progressive visual loss in Retinitis Pigmentosa leads to cortical and subcortical reorganization of the human brain

Purpose Retinitis Pigmentosa (RP) is a retinal disease characterized by photoreceptor degeneration. Usually, symptoms are early onset night blindness followed by progressive peripheral vision loss, with central vision being later affected. Some patients become blind after several years of disease. We studied the consequences of this progressive loss of visual input in the human brain using Magnetic Resonance Imaging.

Brain structural and functional reorganization due to long term retinal peripheral degeneration in retinitis pigmentosa

Purpose Retinitis Pigmentosa (RP) is a rare retinal disease with progressive degeneration of photoreceptors leading to early peripheral and later central visual loss. It provides a model to analyze visual cortex plasticity since onset age ranges from infancy to adulthood. Prior studies have mostly covered structural or functional alterations in the same cohort; hence we aimed to determine the impact of RP on brain function and structure using magnetic resonance imaging.

Evaluation of nursing perceptions about three insulin protocols for blood glucose control in critical care

In order to implement a tight glycemic control protocol in the ICU it is essential to obtain active nurse involvement. Our objective was to evaluate nurses perception about three different blood glucose control protocols for critically ill patients.