Assessment of toxicity of a glyphosate-based formulation using bacterial systems in lake water

A new Aeromonas bioassay is described to assess the potential harmful effects of the glyphosate-based herbicide, Roundup^®, in the Albufera lake, a protected area near Valencia. Viability markers as membrane integrity, culturability and β-galactosidase production of Aeromonas caviae were studied to determine the influence of the herbicide in the bacterial cells. Data from the multifactor analysis of variance test showed no significant differences (P > 0.05) between A. caviae counts of viability markers at the studied concentrations (0, 50 and 100 mg l⁻¹ of glyphosate).

The effects of Roundup^® on microbial biota present in the lake were assessed by measuring the number of indigenous mesophilic Aeromonas in presence of different amounts of the herbicide at 0, 50 and 100 mg l⁻¹ of glyphosate. In samples containing 50 and 100 mg l⁻¹ of glyphosate a significant (P < 0.05) increase in Aeromonas spp. counts and accompanying flora was observed.

The acute toxicity of Roundup^® and of Roundup^® diluted with Albufera lake water to Microtox^® luminescent bacterium (Vibrio fischeri) also was determined. The EC₅₀ values obtained were 36.4 mg l⁻¹ and 64.0 mg l⁻¹ of glyphosate respectively. The acidity (pH 4.5) of the herbicide formulation was the responsible of the observed toxicity.     

Modelling annual pasture dynamics: Application to stomatal ozone deposition

Modelling ozone (O₃) deposition for impact risk assessment is still poorly developed for herbaceous vegetation, particularly for Mediterranean annual pastures. High inter-annual climatic variability in the Mediterranean area makes it difficult to develop models characterizing gas exchange behaviour and air pollutant absorption suitable for risk assessment. This paper presents a new model to estimate stomatal conductance (g_s) of Trifolium subterraneum, a characteristic species of dehesa pastures. The MEDPAS (MEDiterranean PAStures) model couples 3 modules estimating soil water content (SWC), vegetation growth and g_s. The g_s module is a reparameterized version of the stomatal component of the EMEP DO₃SE O₃ deposition model. The MEDPAS model was applied to two contrasting years representing typical dry and humid springs respectively and with different O₃ exposures. The MEDPAS model reproduced realistically the g_s seasonal and inter-annual variations observed in the field. SWC was identified as the major driver of differences across years. Despite the higher O₃ exposure in the dry year, meteorological conditions favoured 2.1 times higher g_s and 56 day longer growing season in the humid year compared to the dry year. This resulted in higher ozone fluxes absorbed by T. subterraneum in the humid year. High inter-family variability was found in gas exchange rates, therefore limiting the relevance of single species O₃ deposition flux modelling for dehesa pastures. Stomatal conductance dynamics at the canopy level need to be considered for more accurate O₃ flux modelling for present and future climate scenarios in the Mediterranean area.     

Environmental load of Cryptosporidium parvum oocysts from cattle manure in feedlots from the central and western United States

The first step in assessing the risk of water contamination by Cryptosporidium parvum oocysts from feedlot cattle (Bos taurus) production systems is to quantify the number of C. parvum oocysts present in the fecal material deposited by feedlot cattle. Our primary objective for this project was to estimate the daily environmental load of C. parvum oocysts in fecal material deposited by feedlot cattle from across the central and western USA. Our secondary goal was to genotype isolates of C. parvum from feedlot cattle to help facilitate proper identification of mammalian sources of waterborne C. parvum. Based on 5274 fecal samples from 22 feedlots in seven states (California, Washington, Colorado, Oklahoma, Texas, Nebraska, and South Dakota), we estimated a point prevalence of C. parvum of 0.99 to 1.08% in fecal material from feedlot pens from a wide range of climates and a diverse range of feedlot management systems. On average, fresh fecal material from throughout feedlot systems (recent arrivals to nearing slaughter) contained about 1.3 to 3.6 oocysts/g feces, which roughly translates to about 2.8 x 10(4) to 1.4 x 10(5) oocysts/animal per day.     

Cytological study and immunohistochemical location of PSP toxins in foot skin of the ormer, Haliotis tuberculata, from the Galician coast (NW Spain)

The ormer, Haliotis tuberculata Linnaeus, 1758, is able to accumulate paralytic shellfish toxins (PST) in the foot side skin. Epidermal and secretory cells are described separately for the pedal side and sole epithelia, as notable differences have been observed. Melanin and photosynthetic pigment granules in the epidermal cells of the foot side epithelium give this skin its appearance and characteristic color. This epidermis also has abundant secretory cells containing at least three kinds of secretory granules. Conversely, the epidermal cells of foot sole epithelium do not have pigment granules, and the secretory cells are mostly subepithelial. Immunohistochemical reaction against PST (saxitoxin and its derivatives) showed that the toxins are located in specific cells of the foot side epithelium, which are distinct from the epidermal cells. Immunofluorescence also reveals toxins throughout many areas of the mucilage covering the epithelium, suggesting the secretory nature of the cells containing the toxins. These results do not show any apparent relationship between melanin or photosynthetic pigment granules and PST content. PST were not detected in the foot sole epithelium either immunohistochemically or by HPLC. Considering the toxic characteristics of ormers described in previous studies and the results presented here, the authors discuss the role of toxins retained or produced by the foot side epithelium Received: 25 July 2000 / Accepted: 7 November 2000     

Comparative sorption,desorption and leaching potential of aminocyclopyrachlor and picloram

Sorption and desorption of aminocyclopyrachlor (6-amino-5-chloro-2-cyclopropylpyrimidine-4-carboxylic acid) were compared to that of the structurally similar herbicide picloram (4-amino-3,5,6-trichloro-2-pyridinecarboxylic acid) in three soils of differing origin and composition to determine if picloram data is representative of aminocyclopyrachlor behavior in soil. Aminocyclopyrachlor and picloram batch sorption data fit the Freundlich equation and was independent of concentration for aminocyclopyrachlor (1/n = 1), but not for picloram (1/n = 0.80–0.90). Freundlich sorption coefficients (K _f) for aminocyclopyrachlor were lowest in the eroded and depositional Minnesota soils (0.04 and 0.12 μmol ^(1–1/n) L^1/n kg^?1) and the highest in Molokai soil (0.31 μmol ^(1–1/n) L^1/n kg^?1). For picloram, K _f was lower in the eroded (0.28 μmol ^(1–1/n) L^1/n kg^?1) as compared to the depositional Minnesota soil (0.75 μmol ^(1–1/n) L^1/n kg^?1). Comparing soil to soil, K _f for picloram was consistently higher than those found for aminocyclopyrachlor. Desorption of aminocyclopyrachlor and picloram was hysteretic on all three soils. With regard to the theoretical leaching potential based on groundwater ubiquity score (GUS), leaching potential of both herbicides was considered to be similar. Aminocyclopyrachlor would be ranked as leacher in all three soils if t_1/2 was > 12.7 days. To be ranked as non-leacher in all three soils, aminocyclopyrachlor t_1/2 would have to be <3.3 days. Calculated half-life that would rank picloram as leacher was calculated to be ～15.6 d. Using the current information for aminocycloprachlor, or using picloram data as representative of aminocycloprachlor behavior, scientists can now more accurately predict the potential for offsite transport of aminocycloprachlor.     

Mercury, methylmercury, and selenium in blood of bird species from Doñana National Park (Southwestern Spain) after a mining accident

Total mercury (Hg), monomethylmercury (MeHg), and selenium (Se) were determined in blood of 11 bird species living in Doñana National Park (DNP, Southwestern Spain) and the surrounding area in 1999 and 2000 after a mine spill accident. The total Hg contents found varied from 1.00 to 587 ng/mL, with an MeHg percentage higher than 80 %, except in mallard species. In all the cases, the concentrations found were below the threshold of high risk for the bird populations. The parameters which most affected the accumulation of Hg and MeHg in the birds studied were, first, species, or trophic position, and second sampling area. Age does not seem to have a great influence on the content of Hg in the blood of these birds. The levels of Se found ranged from 108 to 873 ng/mL, and they were not affected by species, trophic level, age, or sampling area. The blood Hg concentrations of birds living in the area directly affected by the toxic mud, outside the park, were higher than those found in the other birds, and this could be explained by the mine spill accident happened in 1998.     

Plant phenology, growth and nutritive quality of Briza maxima: responses induced by enhanced ozone atmospheric levels and nitrogen enrichment

An assessment of the effects of tropospheric ozone (O₃) levels and substrate nitrogen (N) supplementation, singly and in combination, on phenology, growth and nutritive quality of Briza maxima was carried out. Two serial experiments were developed in Open-Top Chambers (OTC) using three O₃ and three N levels. Increased O₃ exposure did not affect the biomass-related parameters, but enhanced senescence, increased fiber foliar content (especially lignin concentration) and reduced plant life span; these effects were related to senescence acceleration induced by the pollutant. Added N increased plant biomass production and improved nutritive quality by decreasing foliar fiber concentration. Interestingly, the effects of N supplementation depended on meteorological conditions and plant physiological activity. N supplementation counteracted the O₃-induced senescence but did not modifiy the effects on nutritive quality. Nutritive quality and phenology should be considered in new definitions of the O₃ limits for the protection of herbaceous vegetation.     

Semifield assessment of the runoff potential and environmental risk of the parasiticide drug ivermectin under Mediterranean conditions

Introduction  

The antiparasitic ivermectin is of particular concern to regulatory agencies. Ivermectin can reach the environment through the direct emission of dung from livestock on pasture and via manure application on agricultural lands.     

Carbon dioxide capture from combustion flue gases with a calcium oxide chemical loop. Experimental results and process development

Post-combustion carbonate looping processes are based on the capture of carbon dioxide from the flue gases of an existing power plant in a circulating fluidized bed reactor (CFB) of calcium oxide (the carbonator) particles. The calcination of calcium carbonate in a new oxy-fired CFBC power plant regenerates the sorbent (calcium oxide particles) and obtains high purity carbon dioxide. This communication presents experimental results from a small test facility (30 kWt) operated in continuous mode using two interconnected CFB reactors as carbonator and calciner. Capture efficiencies between 70 and 97% have been obtained under realistic flue gas conditions in the carbonator reactor (temperatures around 650 °C). The similarity between process conditions and those existing in CFBC power plants should allow a rapid scaling up of this technology. The next steps for this process development are also outlined.