Spatial and temporal population dynamics of the crown-of-thorns starfish,Acanthaster planci,over a 24-year period along the central west coast of Okinawa Island,Japan

Boom and bust dynamics are a prominent characteristic of the crown-of-thorns starfish (Acanthaster planci) populations. Outbreaking starfish populations damage coral communities extensively and then often disappear quickly. In contrast, Onna village, on the central west coast of Okinawa Island, Japan, has been experiencing chronically high population densities of A. planci for decades. In this study, we examined spatial and temporal population dynamics of A. planci along the coast of Onna village, using removal data gathered over 24 years by a local fisheries cooperative. The results demonstrate that A. planci populations along the Onna coast often experienced high densities prior to 2003 and that recently, populations have again been increasing drastically. Size-frequency distributions suggest multiple, successive recruitment, as one of the driving factors maintaining A. planci populations in this location. Moreover, within the Onna area, the timing of outbreak peaks varied among different locations, showing a northward progression.     

High-performance liquid chromatography with conductimetric detection of perfluorocarboxylic acids and perfluorosulfonates

A rapid and simple method for separating and determining various environmentally harmful perfluorocarboxylic acids and perfluorosulfonates was successfully developed using high- performance liquid chromatography with conductimetric detection, for product and waste management of these compounds at manufacturing and processing sites. Compounds having C(3)-C(8) perfluoroalkyl groups were separated using a Tosoh TSKgel Super-ODS column and a mobile phase consisting of a mixture of methanol and aqueous NaH(2)PO(4) at several mixing ratios. The best detection limits for the compounds ranged from 0.12 to 0.66 mg l(-1) (ppm), and linear calibration graphs were obtained up to 87-109 mg l(-1). The combination of this method with concentration of the sample by solid-phase extraction with cartridges based on styrene-divinylbenzene-copolymer enabled the determination of approximately 50 microg l(-1) (ppb) for compounds with C(4)-C(8) perfluoroalkyl groups. This method was successfully used to monitor the artificial decomposition of the perfluorocarboxylic acid n-C(4)F(9)COOH induced by a photocatalyst.     

Trichloroethylene decomposition and in-situ dry sorption of Cl-products by calcium oxides prepared from hydrated limes

A comparison of CaOs produced by calcining two types of hydrated lime and calcium carbonate was made for decomposition of trichloroethylene and in-situ dry sorption of the decomposed Cl-products using a lab-scale gas flow type tubular packed bed reactor. About 20 mg of CaO sample was mixed with about 2 g of Al₂O₃ particles and packed in the reactor and allowed to react with a flowing standard gas containing 500 ppm of C₂HCl₃ (N₂ balance) at 673 and 873 K, under the condition that the reaction of CaO with C₂HCl₃ might be completed within a few hours.It was found that no thermal decomposition of C₂HCl₃ at or below 673 K was observed in a reactor packed only with Al₂O₃ particles. However, a considerable amount of decomposition of C₂HCl₃ was obtained in a reactor packed with CaO and Al₂O₃, even at 673 K. For 1 mol of CaO prepared by calcining highly reactive Ca(OH)₂ at 673 K, decomposition of 0.42 mol of C₂HCl₃ and in-situ absorption product of 0.53 mol of CaCl₂ were obtained. At 873 K, about 46% of C₂HCl₃ was thermally decomposed. The total amount of C₂HCl₃ decomposed in CaO-Al₂O₃ particle bed at 873 K became nearly twice larger than that at 673 K. For 1 mol of CaO prepared by calcining highly reactive Ca(OH)₂ at 873 K, decomposition of 0.59 mol of C₂HCl₃ and in-situ absorption product of 0.67 mol of CaCl₂ were obtained. Small amounts of C₂Cl₂, C₂Cl₄, CCl₄, etc. were detected during decomposition of C₂HCl₃ at 673 and 873 K.It was recognized that the data on decomposition of C₂HCl₃ as well as in-situ dry sorption of Cl-products in CaO particle bed were correlated with specific surface area of the CaO employed.     

Quantification of free and esterified long-chain fatty acids without extraction by high-performance liquid chromatography in anaerobic digestion sludge

Journal of Material Cycles and Waste Management - During anaerobic digestion, the concentrations of long-chain fatty acids (LCFAs) need to be monitored to achieve good performance due to their...     

Arsenic Removal from Dilute Solutions by High Surface Area Mesoporous Iron Oxyhydroxide

Mesostructured iron oxyhydroxide (FeO _x ) and iron oxyhydroxide–phosphate (FeO _x P) composites were organized using dodecylsulfate surfactant as a template. X-ray diffraction studies depicted a lamellar structure of the product. Ion exchange and solvent extraction methods were employed for the removal of the surfactant. Carboxylate ions exchanged lamellar type mesostructured material reorganized to a wormhole-like mesoporous material when heated under N₂ atmosphere. Surfactant was completely removed by carboxylate ions as observed by the Fourier transform infrared spectra. High surface area acetate-exchanged FeO _x (230 m² g^?1) was obtained after the surfactant removal from the composite (2.8 m² g^?1). Surface area of acetate-exchanged FeO _x P was the highest (240 m²g^?1) after the removal of the surfactant. Local structure of iron species of FeO _x was investigated by X-ray absorption fine structure spectroscopy. Further, Fe···Fe bond appeared at 3.21–3.25 Å with coordination number 2–3, showing a high degree of un-saturation of Fe···Fe bonds. As compared with bulk iron oxyhydroxide and iron-intercalated montmorillonite, the mesoporous iron materials were highly effective for arsenic removal from low concentrations of aqueous solutions. Furthermore, mesoporous iron materials were stable in aqueous phase.