José Antonio Rodríguez

Effects of municipal solid waste compost and mineral fertilizer amendments on soil properties and heavy metals distribution in maize plants (Zea mays L.).

Soil amendments based on crop nutrient requirements are considered a beneficial management practice. A greenhouse experiment with maize seeds (Zea mays L.) was conducted to assess the inputs of metals to agricultural land from soil amendments. Maize seeds were exposed to a municipal solid waste (MSW) compost (50 Mg ha(-1)) and NPK fertilizer (33 g plant(-1)) amendments considering N plant requirement until the harvesting stage with the following objectives: (1) determine the accumulation of total and available metals in soil and (2) know the uptake and ability of translocation of metals from roots to different plant parts, and their effect on biomass production. The results showed that MSW compost increased Cu, Pb and Zn in soil, while NPK fertilizer increased Cd and Ni, but decreased Hg concentration in soil. The root system acted as a barrier for Cr, Ni, Pb and Hg, so metal uptake and translocation were lower in aerial plant parts. Biomass production was significantly enhanced in both MSW and NPK fertilizer-amended soils (17%), but also provoked slight increases of metals and their bioavailability in soil. The highest metal concentrations were observed in roots, but there were no significant differences between plants growing in amended soil and the control soil. Important differences were found for aerial plant parts as regards metal accumulation, whereas metal levels in grains were negligible in all the treatments.

Chromium(VI) Removal from Aqueous Solution by Magnetite Coated by a Polymeric Ionic Liquid-Based Adsorbent

An evaluation of the chromium(VI) adsorption capacity of four magnetite sorbents coated with a polymer phase containing polymethacrylic acid or polyallyl-3-methylimidazolium is presented. Factors that influence the chromium(VI) removal such as solution pH and contact time were investigated in batch experiments and in stirred tank reactor mode. Affinity and rate constants increased with the molar ratio of the imidazolium. The highest adsorption was obtained at pH 2.0 due to the contribution of electrostatic interactions.

Synthesis and Characterization of Amide Stationary Phases for the Determination of Sulfonamides by Sequential Injection Chromatography

ABSTRACT The synthesis of amide (butyl, cyclohexyl, and phenyl) modified silica and the use as stationary phases in sequential injection chromatography are described. The system was tested on the isocratic separation of seven sulfonamides (sulfachloropyridazine, sulfadimethoxine, sulfamethazine, sulfamethoxazole, sulfamethoxypyridazine, sulfaquinoxaline, and sulfathiazole) using each stationary phase with mobile phases composed of acetonitrile/water at a flow rate of 0.45 mL min−1. A mixed mode retention mechanism of sulfonamides in the stationary phases was obtained, including dipole-dipole, π-π, and hydrogen bonding interactions. The most appropriate phase for the separation of sulfonamides was phenylamide. The chromatographic behavior was confirmed using density functional theory of the interaction between sulfamethoxazole and the stationary phases.

Recent Advances in the Extraction of Triazines from Water Samples

The use of herbicides in agriculture has helped to improve crop quality and yield. However, the presence of such substances has also caused serious environmental pollution problems. Triazine herbicides are a group of herbicides applied in agriculture for preand post-emer‐ gence weed control. The first report of the use of triazine derivatives was in 1952 by J.R. Geigy from Switzerland but it was not until 1954 that chlorazine was used as a herbicide, followed by simazine in 1955 [1]. During subsequent years the amount of commercially available triazines increased. The main triazine herbicides are derived from s-triazine, a six member heterocycle with symmetrically located atoms in which positions 2, 4 and 6 are substituted. The stereochemical stability of s-triazines is large enough to persist in environmental samples from several months to many years [2].

Sequential Injection Anodic Stripping Voltammetry at Tubular Gold Electrodes for Inorganic Arsenic Speciation

Arsenic is one of the most feared contaminants because of its high toxicity at low concentrations. Exposure to high levels of arsenic can cause problems in humans ranging from gastrointestinal symptoms to arsenicosis. Once this element is dissolved in water and is ingested, it is accumulated in the body. Contamination of groundwater with arsenic is one of the major environmental and public health problems on a global scale (NRC, 1999).

Electrochemical behavior Zn(II) at carbon steel electrode in deep eutectic solvents based on choline chloride

Deep eutectic solvents prepared by mixture of choline chloride with urea, thiourea and ethylene glycol (1:2 molar ratio) were used to study the electrochemical behavior Zn(II) at carbon steel 1018 electrode. Zn deposits were immersed in a corrosive media (NaCl 3%wt). Composition of the solvent employed causes a difference in electrodeposition and corrosion behaviors, being diffusion coefficient value a critical parameter associated to these processes.

Extraction: Magnetic Materials in Separation Science

Sample pretreatment is one of the most important steps in chemical analysis. Extensive clean-up procedures are normally required to remove matrix components which may interfere in the analysis. Some common strategies to these steps are based on the liquid-liquid extraction or solid phase extraction (SPE) techniques, in which the separation occurs by the analyte partition coefficient between the sample solution phase and the solid sorbent. SPE with magnetic particles (MPSE, magnetic solid phase extraction) has several merits such as lower cost, higher enrichment factor and less consumption of organic solvents.

Chemometric Strategies for the Extraction and Analysis Optimization of Herbicide Residues in Soil Samples

1.1 Herbicide benefits and concerns The two cereal crops which are grown most abundantly in the EU are wheat and barley (Document No. SANCO/D3/SI2.396179, 2005). Herbicides play a very important role in effectively controlling annual grasses and broad-leaved weeds affecting these crops. Their use cannot be neglected due to the enormous benefits in agricultural outputs. Among them, acidic herbicides are widely used for control of broad-leaved weeds and other vegetation because they are relatively inexpensive and very potent even at low concentrations (Wells & Yu, 2000). However, due to the herbicide widespread and possible toxicity in the environment, it is important to monitor their residues. Under realistic field situations there is a potential exposure to agricultural soils by these products indirectly through spray drift and run-off from crop vegetation surfaces, and directly through soil treatment practices (Document No. D/00/SuM/5277, 2000). They have harmful effects on the microflora of the soil when they are not degraded quickly enough (Santos-Delgado et al., 2000).