Changes in water-extractability of soil inorganic phosphate induced by chloride and sulfate salts

GOAL, SCOPE AND BACKGROUND: One of the principal experimental variables which effect the results of phosphorus (P) sorption studies is the ionic composition, in addition to both species and concentrations of the contacting solution. In spite of the realization that ionic species, concentrations and their compositions effect P sorption and/or desorption, most of the salt-related studies are confined to Cl- (anion) in association with different cations. While the knowledge about the comparative response of P to Cl- and SO4(2-) ions was lacking, the current study was conducted to evaluate the comparative effects of anions (in association with cations) on inorganic P release and P fractions in the soil. METHODS: The test soil was amended with livestock compost manure (OP); KH2PO4 (IPk) or Ca(H2PO4)2 (IPc) at a rate of 1ppm. Soil was subjected to one salt and nine subsequent water extractions and different P fractions were measured. Four salt types, NaCl, Na2SO4, KCl and K2SO4, were used at levels of 0.5 M. RESULTS: Irrespective of P sources, P release was substantially increased in the salt-pretreated soil as compared to the non-saline soil. Sulfate salts released more P in subsequent water extractions than Cl-. Phosphorus release decreased for salt types with Na2SO4 > NaCl > K2SO4 > KCl and for P sources with OP approximately IPk > Control (without P application) > IPc, respectively. DISCUSSION: No previous study was found to compare the results of more P release by SO4(2-) than Cl- salt. Most of the previous studies focused on anion sorption capacities, but the mechanism for their adsorption is not fully known. Most of the authors suggested that the mechanisms of SO4(2-) and PO4(3-) adsorption are similar, and that both ions compete for the same sorption sites (Kamprath et al. 1956, Couto et al. 1979, Pasricha and Fox 1993). Although adsorbed SO4(2-) does not compete strongly with PO4(3-), there is likely to be some competition for sorption between these anions which may cause comparatively more P release by SO4(2-) than Cl- salts. Higher P release by Na-saturation could be due to the release of P associated with oxide surfaces or due to dissolution of Ca-P phases (Curtin et al. 1987). CONCLUSIONS: Study clearly showed that not only cations species differ for P desorption capacity, but associated anions also play a vital role in the fate of P under saline environments. Synergetic effects exist between Na and SO4(2-) ions which enhanced the P release. This study has also confirmed the fact that P from organic sources is available as well as from inorganic P sources. However, P release depends more on the type of P source applied than on total P. RECOMMENDATIONS AND PERSPECTIVES: It is highly recommended that more than one anion species must be used in the research plans for evaluating the P response in a saline environment. The results have important implications from the point of view of research, as most of the researchers focus on different cations only for evaluating P response to salts from an environmental point of view. However, our study has made it clear that anions in association with cations differed for their effects on P release.     

日本职业卫生管理及对中国的启示

依据中日合作项目<加强中国国家安全生产科学技术能力计划>成果,系统介绍了日本职业卫生监管机构、法规、职业病确定、作业环境管理等.同时,结合中国职业卫生管理体制尚未完全理顺、法规较滞后、专业人才不足、企业基础资料不全和自主管理体制不健全等现状,提出了进一步明确职业卫生管理体制、完善职业卫生法规、建立职业卫生统计制度、强化企业自主管理能力等建立健全中国职业卫生管理的对策和建议.本文对完善中国职业卫生管理具有重要的参考意义.     

日本职业卫生管理及对中国的启示

依据中日合作项目《加强中国国家安全生产科学技术能力计划》成果,系统介绍了日本职业卫生监管机构、法规、职业病确定、作业环境管理等。同时,结合中国职业卫生管理体制尚未完全理顺、法规较滞后、专业人才不足、企业基础资料不全和自主管理体制不健全等现状,提出了进一步明确职业卫生管理体制、完善职业卫生法规、建立职业卫生统计制度、强化企业自主管理能力等建立健全中国职业卫生管理的对策和建议。本文对完善中国职业卫生管理具有重要的参考意义。     

Effect of carbon tetrachloride on sonochemical decomposition of methyl orange in water

Two types of sonicators were used for the sonochemical decomposition of methyl orange (MO) in the presence and absence of carbon tetrachloride (CCl4): One is a 45kHz ultrasonic cleaning bath (a low intensity sonicator) and the other is a 200kHz ultrasonic reactor (a high intensity sonicator). It was clearly confirmed that the rates of the sonochemical decomposition of MO increased with increasing the concentration of CCl4 in both sonicators. The enhancement effect of CCl4 was much higher in the high intensity sonicator than in the low intensity one: by the addition of 100ppm of CCl4, the decomposition ratio of MO with the high intensity sonicator became 41 times larger, while that with the low intensity sonicator became 4.8 times larger. Based on the obtained results, it was suggested that the formed cavitation phenomenon was different between sonicators. It was also suggested that the sonochemical decomposition of MO in the presence of CCl4 would be useful to evaluate the sonochemical efficiency, because the rate of MO decomposition can be effectively enhanced by the sonolysis of CCl4.     

Bioavailability of pollutants sets risk of exposure to biota and human population in reservoirs from Iguaçu River (Southern Brazil)

Environmental Science and Pollution Research - The Iguaçu River, located at the Southern part of Brazil, has a great socioeconomic and environmental importance due to its high endemic fish...     

Mechanism and Characterization of Polyamide 4 Degradation by <Emphasis Type="Italic">Pseudomonas</Emphasis> sp.

We identified a biodegrading microorganism of polyamide (nylon) 4, a linear polymer of γ-aminobutyric acid (GABA). From activated sludge, the biodegrading bacteria strains of Pseudomonas sp. were isolated and identified by their taxonomic characteristics and nucleotide sequences of 16S rDNA. One strain, ND-11, was grown on a minimal medium containing polyamide 4 (PA4) as the sole carbon source. The strain produced GABA as a degradation intermediate, as identified by analyzing the NMR spectra of degraded products. The culture supernatant of strain ND-11 degraded the emulsified PA4 completely within one day. These results suggest that the ND-11 strain degraded PA4 using its extracellular enzymes to hydrolyze amide bonds.     

The effects of pH on fluoxetine in Japanese medaka (Oryzias latipes): acute toxicity in fish larvae and bioaccumulation in juvenile fish

Recent detection of fluoxetine in the aquatic environment and fish suggests a possibly high accumulation of fluoxetine; however, no report is available on the bioaccumulation of fluoxetine in aquatic organisms. Since bioaccumulation of fluoxetine was probably dependent on pH near the pK(a) value of 10.1, experiments were conducted approximately at pH 7, 8, and 9. Distribution coefficients between 1-octanol and water (D(ow)), and those between synthetic membrane vesicles (liposomes) and water (D(lip-wat)) were determined at pH 7, 8, and 9. The D(ow) and D(lip-wat) values increased significantly with increasing pH. Acute toxicity tests were performed using Japanese medaka (Oryzias latipes) prior to the bioaccumulation test, and 96-h LC(50) values were 5.5, 1.3, and 0.20mgl(-1) at pH 7, 8, and 9, respectively. In the bioaccumulation test, concentrations of fluoxetine and its major metabolite, norfluoxetine, in the fish body and liver were measured. The bioconcentration factors (BCF) of fluoxetine for Japanese medaka were 8.8, 3.0x10, and 2.6x10(2) in the body and 3.3x10(2), 5.8x10(2), and 3.1x10(3) in the liver at pH 7, 8, and 9, respectively. The BCF values were lower at pH 7 and higher at pH 9 mainly because of the increase in nonionized species with significantly higher hydrophobicity than the ionized species at pH values closer to pK(a). A similar trend was obtained for the concentration of norfluoxetine in the fish but the pseudo-BCF values (the ratio of the norfluoxetine concentration in the fish and the fluoxetine concentration in test water) were higher than the BCF value of fluoxetine at all pH conditions.     

Changes in the flood regime of S?o Francisco River (Brazil) from 1940 to 2006

Flow regulation causes various environmental impacts in the downstream reaches of impounded rivers. The S?o Francisco River (SF) basin is Brazil’s third most important watershed. Several dams have been built in its course in the last four decades, mostly for flow regulation and hydropower generation. This paper presents an evaluation of historical changes in the flood regime. Three regions of the SF River basin, which are under the influence of different levels of regulation, were studied: the lower, middle, and upper SF River. The components of magnitude, frequency, and duration of floods were quantified for each region from 1940 to 1960 (prior to the construction of the first dam) and from 1986 to 2006 (after the last dam). The results have shown the inexistence of big floods in the downstream areas, decreasing durations of small floods as well as significant changes in the annual seasonality of floods. Reductions in the flood frequency were verified in all stretches, even in non-regulated systems, such as the lower Velhas River. The climate variation, which occurred in both period, was not able to explain the changes in the flood regime of S?o Francisco River; therefore, dams and other anthropogenic activity are the main factors promoting the temporal variability of streamflows in the S?o Francisco basin.