Influence of organic matter removal on competitive and noncompetitive adsorption of copper and zinc in acid soils.

We studied competitive and noncompetitive adsorption of copper and zinc in four acid soils, and compared the behavior of the two metals in untreated samples and samples treated with hydrogen peroxide to remove organic matter in the soil. Copper exhibited stronger competitive adsorption than zinc in the untreated samples. However, removal of organic matter reduced copper adsorption to a greater extent than zinc adsorption, the two metals exhibiting a more similar adsorption pattern than the untreated samples. The presence of copper dramatically reduced zinc competitive adsorption in untreated samples; on the other hand, that of zinc only resulted in slightly reduced competitive adsorption of copper. The hydrogen peroxide treatment decreased competitive adsorption in both metals; however, copper continued to be more efficient than zinc in competing for binding sites on adsorbing surfaces. Desorption of Cu occurred much less readily than desorption of Zn and hysteresis is apparent especially for Cu.

Changes in soil properties and in the growth of Lolium multiflorum in an acid soil amended with a solid waste from wineries.

The agronomic utility of a solid waste, waste perlite (WP), from wine companies was assessed. In this sense, the natural characteristics of the waste were measured, followed by the monitoring of its effects on the chemical properties of acid soils and the growth of Lolium multiflorum. Taking into account that heavy metals associated to the waste (such as Cu, Zn and Mn) could cause problems when used as amendment, the changes in their total levels and in their soil fractionation were also studied, together with their total contents in L. multiflorum. The high content in C (214gkg(-1)), N (25gkg(-1)), P (534mgkg(-1)) and K (106gkg(-1)) of WP turned it into an appropriate amendment to increase soil fertility, solving at the same time its disposal. WP contributed to increase soil pH (in 2 pH units) and cation exchange capacity (CEC increased in 3cmolckg(-1)units), but reduced the potential Cu phytotoxicity due to a change in Cu distribution towards less soluble fractions. The growth of L. multiflorum adequately responds to the treatment with WP at addition rates below 2.5gkg(-1), whereas the imbalance between nutrients can justify the reduction in biomass production at higher WP addition rates. The levels of heavy metals analyzed in L. multiflorum biomass (8-85gkg(-1)) do not seem to cause undesirable effects on its growth.

Seasonal distributions of fungicides in soils and sediments of a small river basin partially devoted to vineyards.

The acid soils of Ourense province riverland (Galicia, NW Spain) produce about 50,000 tons of grapes for winemaking. As part of ongoing investigations into fungicide transport in Ourense vineyard soils, the occurrence of several fungicides in such soils was investigated. Soil samples were collected from the inter-row topsoil of a vineyard adjacent to the River Alongos, approximately 15 km SW of the main city of Ourense. The vines were grown in sandy loam with moderate organic carbon (OC) content (1-2%). Fungicide residues were measured in vineyard soils and river sediments by solid-liquid extraction followed by gas chromatography with mass spectrometric detection (GC-MSD). Procymidone and cyprodinil occurred at higher levels in river sediments than in the case of fludioxonil, metalaxyl and penconazole. The highest concentrations of procymidone in sediments were still low (29-57 microg/kg or ppb) suggesting that no accumulation of these compounds occur. All of them were found at higher concentrations in soil; maxima concentrations were about 1000 microg/kg for procymidone and metalaxyl, and about 400 microg/kg for cyprodinil, fludioxonil and penconazole. Folpet was never detected (detection limit lower than 2 microg/kg) in soil and sediments, suggesting that this fungicide was unstable in such samples. The frequency of fungicide detections in soils can be related to their applications in vineyards and the effect of washing off through vineyard canopy by rainfalls. The results found suggest that the vineyard soils of this region are unlikely to be prone to transport of fungicides, and therefore water supplies in this area are unlikely to be at any significant risk of contamination through viticultural use of these compounds.

Attenuation of groundwater contamination caused by cattle slurry: a plot-scale experimental study.

Infiltration of contaminants was investigated in a flat pasture plot Lolium perenne L. which received 250 m3/ha of cattle slurry. Lysimeters and piezometers had previously been installed in the plot to sample groundwater at different depths. Water samples were analysed for pH, conductivity, NH4(+), NO3-, orthophosphate, Cl-, Na+, K+, Ca2+, Mg2+ and chemical oxygen demand (COD), and for faecal coliforms and faecal streptococci. Contaminant concentrations in water samples taken in lysimeters at a depth of 5 cm (2 h after slurry application) were already from 22% to 83%, of raw slurry. After slurry application and after 150 mm of rainfall, contaminant concentrations in groundwater were in all depths less than 95% of those initially measured in the slurry. For all contaminants except Cl-, NO3-, K+ and COD, concentrations in groundwater measured before application were reached within 15 days. Mechanical retention was the principal mechanism of attenuation of microorganism and COD levels, whereas cations were attenuated by sorption to soil matrix. Dilution by rain water had less significant effects, accounting for about a tenfold reduction in contaminant levels.

Surface runoff pollution by cattle slurry and inorganic fertilizer spreading: chemical oxygen demand, ortho-phosphates, and electrical conductivity levels for different buffer strip lengths.

As a way of dealing with the removal of pollutants from farming practices generated wastewater in the EU, we investigate the effect of spreading cattle slurry and inorganic fertiliser on 8 x 5 m2 and 8 x 3 m2 areas, referred to surface runoff chemical oxygen demand (COD), ortho-phosphates (o-P) and electrical conductivity (EC) levels, and the efficiency of grass buffer strips of various lengths in removing pollutants from runoff. The experimental plot was a 15% sloped Lolium perenne pasture. Surface runoff was generated by means of a rainfall simulator working at 47 mm h-1 rainfall intensity. Runoff was sampled by using Gerlach-type troughs situated 2, 4, 6 and 8 m downslope from the amended areas. During the first rainfall simulation, COD, o-P and EC levels were consistently higher in the slurry zone, more evidently in the larger amended area. During the second and third rainfall simulations, concentration and mass levels show a downslope drift into the buffer zones, with no clear buffer strip length attenuation. Correlation between runoff and mass drift is clearly higher in the slurry zone. Percentage attenuation in COD and o-P levels, referred to initial slurry concentrations--including rainfall dilution--were higher than 98%, and higher than 90% for EC.

Quaternary herbicides retention by the amendment of acid soils with a bentonite-based waste from wineries.

The agronomic utility of a solid waste, waste bentonite (WB), from wine companies was assessed. In this sense, the natural characteristics of the waste were measured, followed by the monitoring of its effects on the adsorption/desorption behaviour of three quaternary herbicides in acid soils after the addition of increasing levels of waste. This was done with the intention of studying the effect of the added organic matter on their adsorption. The high content in C (294 g kg(-1)), N (28 g kg(-1)), P (584 mg kg(-1)) and K (108 g kg(-1)) of WB turned it into an appropriate amendment to increase soil fertility, solving at the same time its disposal. WB also reduced the potential Cu phytotoxicity due to a change in Cu distribution towards less soluble fractions. The adsorption of the herbicides paraquat, diquat and difenzoquat by acid soils amended with different ratios of WB was measured. In all cases, Langmuir equation was fitted to the data. Paraquat (PQ) and diquat (DQ) were adsorbed and retained more strongly than difenzoquat (DFQ) in the acid soil studied. However, the lowest retention of DFQ in an acid soil can be increased by amendment with organic matter through a solid waste from wineries, and it is enough for duplicate retention a dosage rate of 10t/ha. Anyway, detritivores ecology can still be affected. Detritivores are the organisms that consume organic material, and in doing so contribute to decomposition and the recycling of nutrients. The term can also be applied to certain bottom-feeders in wet environments, which play a crucial role in benthic ecosystems, forming essential food chains and participating in the nitrogen cycle.