Fractionation and bioavailability of phosphorus in a tropical estuary, Southwest India

Phosphorus fractionation was employed to find the bioavailability of phosphorus and its seasonal variations in the Panangad region of Cochin estuary, the largest estuarine system in the southwest coast of India. Sequential extraction of the surficial sediments using chelating agents was taken as a tool for this. Phosphate in the water column showed seasonal variations, with high values during the monsoon months, suggesting external runoff. Sediment texture was found to be the main factor influencing the spatial distribution of the geochemical parameters in the study region. Similarly, total phosphorus also showed granulometric dependence and it ranged between 319.54 and 2,938.83 μg/g. Calcium-bound fraction was the main phosphorus pool in the estuary. Significant spatial variations were observed for all bioavailable fractions; iron-bound inorganic phosphorus (5.04–474.24 μg/g), calcium-bound inorganic phosphorus (11.16–826.09 μg/g), and acidsoluble organic phosphorus (22.22–365.86 μg/g). Among the non-bioavailable phosphorus, alkalisoluble organic fraction was the major one (51.92– 1,002.45 μg/g). Residual organic phosphorus was K. R. Renjith (B) · N. Chandramohanakumar · M. M. Joseph Department of Chemical Oceanography, School of Marine Sciences, Cochin University of Science and Technology, Kochi 682016, Kerala, India e-mail: renjithaqua@gmail.com comparatively smaller fraction (3.25–14.64% of total). The sandy and muddy stations showed distinct fractional composition and the speciation study could endorse the overall geochemical character. There could be buffering of phosphorus, suggested by the increase in the percentage of bioavailable fractions during the lean premonsoon period, counteracting the decreases in the external loads. Principal component analysis was employed to find the possible processes influencing the speciation of phosphorus in the study region

Effects of fertility management strategies on phosphorus bioavailability in four West African soils

Low phosphorus (P) in acid sandy soils of the West African Sudano-Sahelian zone is a major limitation to crop growth. To compare treatment effects on total dry matter (TDM) of crops and plant available P (P-Bray and isotopically exchangeable P), field experiments were carried out for 2 years at four sites where annual rainfall ranged from 560 to 850 mm and topsoil pH varied between 4.2 and 5.6. Main treatments were: (i) crop residue (CR) mulch at 500 and 2000 kg ha^-1, (ii) eight different rates and sources of P and (iii) cereal/legume rotations including millet (Pennisetum glaucum L.), sorhum [Sorghum bicolor (L.) Moench], cowpea (Vigna unguiculata Walp.) and groundnut (Arachis hypogaea L.). For the two Sahelian sites with large CR-induced differences in TDM, mulching did not modify significantly the soils' buffering capacity for phosphate ions but led to large increases in the intensity factor (C_p) and quantity of directly available soil P (E_1min). In the wetter Sudanian zone lacking effects of CR mulching on TDM mirrored a decline of E_1min with CR. Broadcast application of soluble single superphosphate (SSP) at 13 kg P ha^-1 led to large increases in C_p and quantity of E_1min at all sites which translated in respective TDM increases. The high agronomic efficiency of SSP placement (4 kg P ha^-1) across sites could be explained by consistent increases in the quantity factor which confirms the power of the isotopic exchange method in explaining management effects on crop growth across the region.

Absolute Kr 4s-electron photoionization cross sections between 30 and 90 eV measured by photon-induced fluorescence spectroscopy (PIFS)

Absolute Kr 4s-electron photoionization cross sections as a function of the exciting-photon energy between 30 and 90 eV were measured by photon-induced fluorescence spectroscopy (PIFS). The measurements were compared with available experimental data and theoretical calculations.

Replicated nil associations of digit ratio (2D:4D) and absolute finger lengths with implicit and explicit measures of aggression. 'Replicaci??n de asociaciones nulas del ratio del segundo y cuarto dedo (2D:4D) y la longitud absoluta de los dedos con medidas de agresi??n impl??citas y expl??citas'

Resumen tomado de la publicaci??n

Absolute Science : pupil book 2.

Ofrece una gran flexibilidad y apoyo para la enseñanza y el aprendizaje de las ciencias y garantiza una transición fluida de la etapa dos a la etapa tres. Todos los capítulos, en el texto del alumno, cuentan con una amplia gama de funciones: las actividades de iniciación al comienzo de cada capítulo que ilustra la ciencia en el mundo real; preguntas de cada capítulo para reforzar el conocimiento; preguntas para toda la clase o grupo de discusión; consejos, sugerencias y recordatorio del aprendizaje anterior. Al final del capítulo preguntas y resumen de las principales ideas y palabras clave para consolidar los conocimientos.

Absolute science : pupil book 3.

Ofrece una gran flexibilidad y apoyo para la enseñanza y el aprendizaje de las ciencias y garantiza una transición fluida de la etapa dos a la etapa tres. Todos los capítulos, en el texto del alumno, cuentan con una amplia gama de funciones: las actividades de iniciación al comienzo de cada capítulo que ilustra la ciencia en el mundo real; preguntas de cada capítulo para reforzar el conocimiento; preguntas para toda la clase o grupo de discusión; consejos, sugerencias y recordatorio del aprendizaje anterior. Al final del capítulo preguntas y resumen de las principales ideas y palabras clave para consolidar los conocimientos.

Absolute science : Year 8 : complete teacher pack CD-Rom.

Este CD-ROM recoge todo el material a partir del año ocho del libro del profesor no especialista. contiene: una detallada lista de temas de cada capítulo que acompaña a las notas del profesor; consejos y sugerencias para la enseñanza; planificación de lecciones contienen actividades de iniciación, junto con las tareas propuestas. Un resumen de las notas para cada lección. Al final de la unidad hoja de registro de la prueba.

Absolute science. Pupil book 1.

Ofrece una gran flexibilidad y apoyo para la enseñanza y el aprendizaje de las ciencias y garantiza una transición fluida de la etapa clave dos /Key Stage 2) a la etapa clave tres (Key Stage 3). Todos los capítulos cuentan con una amplia gama de actividades: de iniciación a la ciencia en el mundo real; preguntas para reforzar el conocimiento ; preguntas para toda la clase o grupo de discusión ; consejos, sigerencias y recordatorio del aprendizaje anterior. Al final del capítulo hay preguntas y resumen de las principales ideas y palabras clave para consolidar los conocimientos adquiridos.

Absolute science : year 7 : complete teacher pack CD-ROM.

CD-ROM donde se recoge todo el material para la transición del nivel dos (Key Stage 2) al nivel tres (Key Stage 3). Contiene una lista detallada de temas de cada capítulo que acompaña a las notas del profesor; consejos y sugerencias para la enseñanza; planificación de lecciones con actividades de iniciación, junto con las tareas propuestas; Un resumen de las notas para cada lección. Al final de la unidad hoja de registro de la prueba.

Relative proportions of polycyclic aromatic hydrocarbons differ between accumulation bioassays and chemical methods to predict bioavailability

Chemical methods to predict the bioavailable fraction of organic contaminants are usually validated in the literature by comparison with established bioassays. A soil spiked with polycyclic aromatic hydrocarbons (PAHs) was aged over six months and subjected to butanol, cyclodextrin and tenax extractions as well as an exhaustive extraction to determine total PAH concentrations at several time points. Earthworm (Eisenia fetida) and rye grass root (Lolium multiflorum) accumulation bioassays were conducted in parallel. Butanol extractions gave the best relationship with earthworm accumulation (r2 ≤ 0.54, p ≤ 0.01); cyclodextrin, butanol and acetone–hexane extractions all gave good predictions of accumulation in rye grass roots (r2 ≤ 0.86, p ≤ 0.01). However, the profile of the PAHs extracted by the different chemical methods was significantly different (p < 0.01) to that accumulated in the organisms. Biota accumulated a higher proportion of the heavier 4-ringed PAHs. It is concluded that bioaccumulation is a complex process that cannot be predicted by measuring the bioavailable fraction alone. The ability of chemical methods to predict PAH accumulation in Eisenia fetida and Lolium multiflorum was hindered by the varied metabolic fate of the different PAHs within the organisms.

Development of a methodology to investigate the importance of chemical speciation on the bioavailability of contaminants to Eisenia andrei

The uptake of metals by earthworms occurs predominantly via the soil pore water, or via an uptake route which is related to the soil pore water metal concentration. However, it has been suggested that the speciation of the metal is also important. A novel technique is described which exposes Eisenia andrei Bouche to contaminant bearing solutions in which the chemical factors affecting its speciation may be individually and systematically manipulated. In a preliminary experiment, the LC50 for copper nitrate was 0.046 mg l(-1) (95 % confidence intervals: 0.03 and 0.07 mg l(-1)). There was a significant positive correlation between earthworm mortality and bulk copper concentration in solution (R-2 = 0.88, P less than or equal to 0.001), and a significant positive increase in earthworm tissue copper concentration with increasing copper concentration in solution (R-2 = 0.97, P less than or equal to 0.001). It is anticipated that quantifying the effect of soil solution chemical speciation on copper bioavailability will provide an excellent aid to understanding the importance of chemical composition and the speciation of metals, in the calculation of toxicological parameters.