Eugenio López-Periago

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.

Occurrence and Downslope Mobilization of Quaternary Herbicide Residues in Vineyard-Devoted Soils

The aim of this study was to examine the fate of quaternary herbicides in soil deposits derived from erosion of vineyard-devoted soils. Herbicide occurrence in the crop soils was due to the farmer application inputs. Special attention should be paid to the presence of paraquat (PQ) in the studied vineyard-devoted soils. The major factor governing the sorption of PQ was the solid state organic fraction with the clay mineral content also making a significant contribution. The mobilization and transport of quats-enriched soil particles may generate downslope and downstream environmental problems that mainly affect detritivore ecology.

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.

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.