Controlled release of carbofuran from an alginate-bentonite formulation: water release kinetics and soil mobility

The insecticide-nematicide carbofuran was incorporated in alginate-based granules to obtain controlled-release (CR) properties. The basic formulation [sodium alginate (1.61%)-carbofuran (0. 59%)-water] was modified by addition of sorbents. The effect on carbofuran release rate, caused by the incorporation of natural and acid-treated bentonite (0.5 and 1.0 M H(2)SO(4)) in alginate formulation, was studied by immersion of the granules in water under shaking. The time taken for 50% of the active ingredient to be released into water, t(50), was longer for those formulations containing natural bentonite (6.1 h) or acid-treated bentonite (9.0 and 11.7 h for 0.5 and 1.0 M H(2)SO(4) treatments, respectively) than for the preparation without bentonite (4.7 h). It appears from the results that the release of carbofuran from the various formulations is controlled by a diffusion mechanism according to the n values obtained, which were close to 0.5 in all cases. The mobility of carbofuran from alginate-based CR formulations was investigated by using soil columns packed with a clay soil (53% clay and 0.08% organic matter). Two alginate-based CR formulations containing natural bentonite or acid-treated bentonite (0.5 M H(2)SO(4)) were compared to technical grade carbofuran. The use of alginate-based CR formulations resulted in a reduction of the leached amount of carbofuran compared with the total amount of pesticide leached using the technical product (50 and 75% for CR granules containing natural and acid-treated bentonite, respectively). Alginate-bentonite CR formulations might be efficient systems for reducing carbofuran leaching in clay soils, which would reduce the risk of groundwater pollution.     

Monitoring of heavy metals in protected forest catchments in Sweden

Long-term integrated catchment monitoring within the Swedish Environmental Monitoring Programme (PMK) aims primarely at the fate and effects of pollutants in mature ecosystems, mainly protected boreal forests. The measurements that were conducted since the early eighties, with some variation, included deposition, throughfall, litterfall and the chemistry of soil water, groundwater and runoff water.Together with, or perhaps partly due to acidification, accumulation and transport of heavy metals are a serious threat to the ecosystem and in the end to the health of human beings. This paper discuss the behaviour of Hg, Pb, Cd, Zn and Cu based on the experiece gained from the studies in the small catchment areas. The importance of present deposition, soil storage and biogeochemical condition for metal mobility to the transport of metals is discussed The storages of Hg and Pb have been built up during a long time span and are very large in comparison with the flux. The present atmospheric deposition have probably little impact on the flux, which rather is governed by the biogeochemical conditions. There is still a small accumulation of Cd, but its great mobility under acidic conditions makes input and output almost in balance. A reduction in deposition will probably have an immediate effect on flux, which also is the case for Zn. Cu generally accumulates in soil. The mobility and hence the flux are certainly regulated by the biogeochemical conditions, but more detailed studies are required to reveal the general mecanisms for Cu transport within the catchment.     

Production of Pearl Millet Irrigated with Different Levels of Brackish Water and Organic Matter

ABSTRACT

The objective is to determine the growth, yield and chemical characteristics of pearl millet irrigated with different levels of brackish water and organic matter in two cultivation cycles. The experimental design was randomized blocks in a 4 × 4 factorial arrangement, composed of 4 levels of brackish irrigation (25, 50, 75 and 100% evapotranspiration), 4 levels of organic matter (0, 15, 30 and 45 t ha^?1) with 3 repetitions. Along two cultivation cycles, pearl millet crop was analyzed for: plant growth variables, fresh and dry mass production, water-use efficiency, and chemical composition. There was significant interaction between applied water levels and organic matter for lignin in the 2nd cut (P < .05). The number of leaves, number of dead leaves and fresh mass production were influenced by the isolated effect of brackish water levels in cut 1 (P < .05). In turn, fresh mass production, dry mass production, plant height, leaves length, panicle length, fresh mass production, crude protein and ether extract were influenced by the isolated effect of saline water levels in the 2nd cut (P < .05). Growth, biomass production and chemical composition variables in second cut are positively influenced by different brackish irrigation levels under low rainfall conditions.     

Prediction chemical composition and alveograph parameters on wheat by near-infrared transmittance spectroscopy

Moisture, protein, wet gluten, dry gluten, and alveograph parameters (W, P, and P/L) of whole wheat grown in different countries around the world were analyzed using near infrared (NIR) transmittance spectroscopy. Modified partial least squares on NIR spectra (850-1048.2 nm) were developed for each constituent or physical property. The best models were obtained for protein, moisture, wet gluten, and dry gluten with r(2) = 0.99, 0.99, 0.95, and 0.96, respectively. Initial alveograph NIR models proposed for all wheat samples did not perform well. However, when wheat samples were divided in two groups depending on W (deformation energy) values, NIR models were highly improved, showing enough prediction accuracy for screening wheat at the receiving stage at mills or elevators.     

Rarity and decline in bumblebees - A test of causes and correlates in the Irish fauna

Bees are believed to be in decline across many of the world’s ecosystems. Recent studies on British bumblebees proposed alternative theories to explain declines. One study suggested that greater dietary specialization among the rarer bumblebee species makes them more susceptible to decline. A second study disputed this theory and found that declines in British bumblebees were correlated with the size of species’ European ranges, leading to the suggestion that climate and habitat specialization may be better indicators of the risk of decline. Here we use a new and independent dataset based on Irish bumblebees to test the generality of these theories. We found that most of the same bumblebee species are declining across the British Isles, but that, within Ireland, a simple food-plant specialization model is inadequate to explain these declines. Furthermore, we found no evidence of a relationship between declines in Irish bumblebees and the size of species’ European ranges. However, we demonstrate that the late emerging species have declined in Ireland (and in Britain), and that these species show a statistically significant westward shift to the extremity of their range, probably as a result of changing land use. Irish data support the finding that rare and declining bumblebees are later nesting species, associated with open grassy habitats. We suggest that the widespread replacement of hay with silage in the agricultural landscape, which results in earlier and more frequent mowing and a reduction in late summer wildflowers, has played a major role in bumblebee declines.     

Dissolved and Particulate Heavy Metals in the Salado River (Santa FE, Argentina)

The objective of this work is to analyze Fe, Mn, Cr, Cd, Cu, Pb, and Zn distributions in the water column in terms of total, dissolved, and particulate concentrations in the Salado River (Santa Fe – Argentina); their relationship with total, dissolved and suspended solids; and the impact of two pollution sources on the watercourse: a stream that collects domestic and industrial wastewater discharges of the region and a direct discharge that releases urban and industrial effluents to the river. Water samples obtained from 5 surveys were analyzed. The Salado River transported a load of heavy metals that ranged from 700 g/s to 2200 g/s of Fe, 20 g/s to 60 g/s of Mn and 1 g/s to 3 g/s of Cr. Results show that most metals were found in particulate form, that the metal input from the direct discharge may be significant at low water levels, whereas a lesser impact was produced by the stream, and that both pollution sources were negligible at high water levels.     

Different tocopherols and the relationship between two methods for determination of primary oxidation products in fish oil

The effectiveness of 2.32 mmol/kg (approximately 1000 ppm) of alpha-, gamma-, or delta-tocopherol (TOH), as well as different levels of alpha TOH, on the formation of hydroperoxides in fish oil was studied by monitoring the peroxide value (POV) and the formation of conjugated dienes (CD) during storage at 30 degrees C. The same order of antioxidant activity was observed by both methods. Linear regression of POV on CD showed that these data were strongly correlated (r(2) > or = 0.98). The value of the slope of the regression lines, however, differed substantially and decreased with increasing hydrogen-donating ability of the different tocopherols and with increasing alpha TOH concentration. It is suggested that this is due, at least in part, to the contribution from hydroxy compounds to the CD measurements and a greater contribution from hydroperoxy epidioxides (two peroxide groups per conjugated diene unit) to the POV than to the CD value. The degrees of formation of both these groups of oxidation products are expected to be influenced by the rate of scavenging of lipid peroxyl and alkoxyl radicals by tocopherol (alpha TOH > gamma TOH > delta TOH).     

Impacts from Deposition on Swedish Forest Ecosystems Identified by Integrated Monitoring

Integrated monitoring of ecosystems (IM) is an international co-operative programme (ICP) to control effects of air pollution and climate change on water, soil and biological systems. It is a part of the Convention on Long-Range Transboundary Air Pollution (CLRTAP) of the United Nations Economic Commission of Europe (UN/ECE). The ICP-IM is undertaken on sites/catchments to investigate acidification, eutrophication and heavy metals with an integrated approach. In Sweden, long-term time series from forest ecosystems, with a long and stable continuity, will reveal trends and changes in processes and enable modelling to be undertaken. Investigations of acidity/alkalinity in relation to mineral and organic acids indicated the importance of atmospheric deposition. Recent results show very high inorganic nitrogen retention (99%), a net loss of sulphur originating mainly from organic horizons, and a high inorganic aluminium content in the illuvial soil horizons which could be detrimental to forests. Forest deficiency could also be caused by an observed ongoing translocation of Zn to deeper soil layers implying a movement towards increased release to surface waters.     

Oxidation of the flavonol quercetin by polyphenol oxidase

Because direct oxidation of flavonols by polyphenol oxidase (PPO) has not previously been reported and, given the importance of flavonols, the ability of broad bean seed PPO to oxidize the flavonol quercetin was studied. The reaction was followed by recording spectral changes with time. Maximal spectral changes were observed at 291 nm (increase) and at 372 nm (decrease). The presence of two isosbectic points (at 272 and 342 nm) suggested the formation of only one absorbent product. These spectral changes were not observed in the absence of PPO. The oxidation rate, which varied with pH, was highest at pH 5.0. The following kinetic parameters were also determined: V(m) = 11 microM/min, K(m) = 646 microM, V(m)/K(m) = 17 x 10(-)(2) min(-)(1). Flavonol oxidation was efficiently inhibited (K(I) = 3.5 microM) by specific PPO inhibitors such as 4-hexylresorcinol. The results obtained showed that quercetin oxidation was strictly dependent on the presence of PPO.