Kinetics and Adsorption Isotherms of Bisphenol A, Estrone, 17β-Estradiol, and 17α-Ethinylestradiol in Tropical Sediment Samples

The sorption of four endocrine disruptors, bisphenol A (BPA), estrone (E1), 17β-estradiol (E2), and 17α-ethinylestradiol (EE2) in tropical sediment samples was studied in batch mode under different conditions of pH, time, and sediment amount. Data obtained from sorption experiments using the endocrine disruptors (EDs) and sediments containing different amounts of organic matter showed that there was a greater interaction between the EDs and organic matter (OM) present in the sediment, particularly at lower pH values. The pseudosecond order kinetics model successfully explained the interaction between the EDs and the sediment samples. The theoretical and experimentally obtained q _e values were similar, and k values were smaller for higher SOM contents. The k _F values, obtained from the Freundlich isotherms, varied in the ranges 4.2–7.4 × 10⁻² (higher OM sediment sample, S₂) and 1.7 × 10⁻³–3.1 × 10⁻² (lower OM sediment sample, S₁), the latter case indicating an interaction with the sediment that increased in the order: EE2 > > E2 > E1 > BPA. These results demonstrate that the availability of endocrine disruptors may be directly related to the presence of organic material in sediment samples. Studies of this kind provide an important means of understanding the mobility, transport, and/or reactivity of this type of emergent contaminant in aquatic systems.     

A first-order analysis of the heat wave in the soil

On the basis of a realistic distribution of the net radiative flux density (composed of a half sinusoid for the shortwave contribution plus a term dependent on the soil surface temperature for the longwave contribution), the solutions regarding the propagation of both the diurnal thermal wave and the heat flux density in the soil are analyzed. The more relevant differences from the analytical solutions obtained under the classical hypothesis of pure sinusoidal forcing waves on the boundary are therefore pointed out.     

Estimation of seed weight, oil content and fatty acid composition in intact single seeds of rapeseed ( Brassica napus} L.) by near-infrared reflectance spectroscopy

The potential of near-infrared reflectance spectroscopy (NIRS) for the simultaneous analysis of seed weight, total oil content and its fatty acid composition in intact single seeds of rapeseed was studied. A calibration set of 530 single seeds was analysed by both NIRS and gas-liquid chromatography (GLC) and calibration equations for the major fatty acids were developed. External validation with a set of 75 seeds demonstrated a close relationship between NIRS and GLC data for oleic (r = 0.92) and erucic acid (r = 0.94), but not for linoleic (r = 0.75) and linolenic acid (r = 0.73). Calibration equations for seed weight and oil content were developed from a calibration set of 125 seeds. A gravimetric determination was used as reference method for oil content. External validation revealed a coefficient of correlation between NIRS and reference methods of 0.92 for both traits. The performance of the calibration equations for oleic and erucic acid was further studied by analysing two segregating F2 seed populations not represented in the calibration set. The results demonstrated that a reliable selection for both fatty acids in segregating populations can be made by using NIRS. We concluded that a reliable estimation of seed weight, oil content, oleic acid and erucic acid content in intact, single seeds of rapeseed is possible by using NIRS technique. This revised version was published online in July 2006 with corrections to the Cover Date.     

Dissolved humic substances supplied as potential enhancers of Cu,Cd, and Pb adsorption by two different mangrove sediments

Journal of Soils and Sediments - The external supply of humic substances has been recently suggested for the remediation of metal-polluted sediments; however, little is known about how to supply...     

Proteolytic digestive enzymes and peritrophic membranes during the development of Plodia interpunctella (Lepidoptera: Piralidae): targets for the action of soybean trypsin inhibitor (SBTI) and chitin-binding vicilin (EvV)

The digestive system of P. interpunctella was characterized during its larval development to determine possible targets for the action of proteinaceous enzyme inhibitors and chitin-binding proteins. High proteolytic activities using azocasein at pH 9.5 as substrate were found. These specific enzymatic activities (AU/mg protein) showed an increase in the homogenate of third instar larvae, and when analyzed by individual larvae (AU/gut), the increase was in sixth instar larvae. Zymograms showed two bands corresponding to those enzymatic activities, which were inhibited by TLCK and SBTI, indicating that the larvae mainly used serine proteinases at pH 9.5 in their digestive process. The presence of a peritrophic membrane in the larvae was confirmed by chemical testing and light microscopy. In a bioassay, P. interpunctella was not susceptible to the soybean trypsin inhibitor, which did not affect larval mass and mortality, likely due to the weak association with its target digestive enzyme. EvV (Erythrina velutina vicilin), when added to the diet, affected mortality (LD50 0.23%) and larval mass (ED50 0.27%). This effect was associated with EvV-binding to the peritrophic membrane, as seen by immunolocalization. EvV was susceptible to gut enzymes and after the digestion process, released an immunoreactive fragment that was bound to the peritrophic matrix, which probably was responsible for the action of EvV.     

Sorption-desorption isotherms and biodegradation of glyphosate in two tropical soils aged with eucalyptus biochar

ABSTRACT

The objective of this study was to evaluate the sorption-desorption process and biodegradation of glyphosate in two tropical soils aged with biochar derived from eucalyptus. The biochar aging period was 30 d. There was little difference between the amounts of sorbed glyphosate in Ultisol (96.8, 96.8 and 96.4%) and Alfisol (97.1, 97.5 and 97.4%) soils that were unamended or amended with biochar aged for 0 or 30 d, respectively. Similar amounts of desorbed herbicide occurred in Ultisol (3.3, 3.3 and 3.4%) and Alfisol (4.1, 4.2 and 3.9%) soils, respectively. The degradation time half-life (DT50) of glyphosate in Ultisol unamended and initial amended were higher (38 and 36 d, respectively) than DT50 in the amended soil with 30 d of biochar aging (27 d); and in the Alfisol DT50 was higher in unamended soil (38 d), and similar in soil unamended at 0 and 30 d of biochar aging (21 and 26 d, respectively). The addition of biochar to two tropical soils or its aging did not have any effect on the sorption and desorption of glyphosate and its biodegradation in relation to the unamended soils, and it can did not affect the transport and persistence of this herbicide in soil.     

Reduction of Hexavalent Chromium in Soil and Ground Water Using Zero-Valent Iron Under Batch and Semi-Batch Conditions

Chemical remediation of soil and groundwater containing hexavalent chromium (Cr(VI)) was carried out under batch and semi-batch conditions using different iron species: (Fe(II) (sulphate solution); Fe⁰ _G (granulated elemental iron); ZVIne (non-stabilized zerovalent iron) and ZVIcol (colloidal zerovalent iron). ZVIcol was synthesized using different experimental conditions with carboxymethyl cellulose (CMC) and ultra-sound. Chemical analysis revealed that the contaminated soil (frank clay sandy texture) presented an average Cr(VI) concentration of 456?±?35 mg kg^?1. Remediation studies carried out under batch conditions indicated that 1.00 g of ZVIcol leads to a chemical reduction of ～280 mg of Cr(VI). Considering the fractions of Cr(VI) present in soil (labile, exchangeable and insoluble), it was noted that after treatment with ZVIcol (semi-batch conditions and pH 5) only 2.5% of these species were not reduced. A comparative study using iron species was carried out in order to evaluate the reduction potentialities exhibited by ZVIcol. Results obtained under batch and semi-batch conditions indicate that application of ZVIcol for the “in situ” remediation of soil and groundwater containing Cr(VI) constitutes a promising technology.     

Interaction Study Between Humin and Phosphate: Possible Environmental Remediation for Domestic Wastewater

The increase in demand for food due to the rapid population growth in recent years has raised the use of fertilizers, particularly phosphate salts. This fact has contributed to the excess amount of phosphorus species in aquatic systems. This is due to the leaching of these species present in the fertilizers applied to the soil to aquatic environments and may lead to eutrophication in these environments. Substances capable of interacting with the phosphate in the aquatic environment are promising for the reduction on the environmental impact. The humin, an insoluble fraction of humic material, has potential for phosphate retention, behaving like a chelating resin. Thus, the purpose of this research was to study the interaction between humin and phosphate. The equilibrium time between humin and phosphate was 15 min, where hydrogenionic potential (pH) 4.0 was the most effective in the interaction process. In this pH, the humin retained 33% of phosphate added. The complexing capacity of the humin-phosphate system was 11.53 mg g^?1. The adsorption studies indicated that the system follows a kinetic pseudo-second-order model. The Freundlich model was the most suitable to describe the phosphate adsorption process in humin. To evaluate the humin application in real systems, humin was added to the domestic wastewater. Sixteen percent of the total phosphate was adsorbed by the humin. Based on these results, humin has the potential to phosphate retention in domestic wastewater and could be used as a chelating resin minimizing environmental impact.