摘要:

Sorption‐desorption studies of imidacloprid (1‐[(6‐chloro‐3‐pyridmyl)methyl]‐N‐mtro‐2‐imidazolidinimine) were conducted using the batch equilibration method with seven U.S. soils varying in their physicochemical properties. Initial imidacloprid concentrations ranged from 3 to 300 μg L‐1. Sorption coefficients Kfand the soil properties organic carbon and CEC gave the higher single correlation coefficients; the latter due to the positive correlation between OC and CEC. Sorption was irreversible and desorption hysteresis in general was greater at low soil solution concentrations. Kfvalues were lower at 1:5 soil:solution ratio than at 1:1, suggesting a possible effect of a soluble soil component, such as salt concentration, on sorption; no significant differences in pH between solutions were detected.

ISSN:0360-1234    

DOI:10.1080/03601239809373134

出版商:Taylor & Francis Group    

年代:1998

数据来源: Taylor

摘要:

The effects of 1/1000 field recommended concentration of the organophosphorus compounds; edifenphos and glyphosate on the immune response and protein contents were investigated after different time intervals. The cell mediated immune response assessed by proliferative response of splenocytes to mitogens; phytohemagglutinin (PHA) and concanavalin A (Con A) for T cell and lipopolysaccharide (LPS) for B cell decreased significantly in tems of the level of stimulation index in the treated fish and reached maximal depression after 4 weeks. Humoral immunity assessed as splenic antibody plaque forming cells (PFC) measured after 5 daysin vitroimmunization to sheep erythrocytes (SRBC's) were suppressed in a concentration dependent pattern by the two compounds. The estimated ED50for the PFC/106cells of edifenphos and glyphosate were 1.48 × 10‐2uM and 1.65 × 10‐2uM respectively. The data also showed that serum antibody titres in the treated fish were decreased in a time dependent manner. The total protein content of serum treated with the two pesticides was decreased after different time periods compared with control. The blood serum of treated and untreatedTilapia niloticawere analyzed electrophoretically for protein components and the percentage of proteins in each fraction was determined.

ISSN:0360-1234    

DOI:10.1080/03601239809373135

出版商:Taylor & Francis Group    

年代:1998

数据来源: Taylor

摘要:

The feeding behavior of the cladoceraDaphnia magnawas studied when subjected to a short‐term exposure to the acaricide tetradifon (4‐chlorophenyl 2,4,5‐trichlorophenyl sulfone). Test species were exposed to sublethal levels of tetradifon and the effect of the toxicant on filtration and ingestion rates was determined. The experiments were performed using the unicellular algaeNannochloris oculatain a density of 5×105cells/mL as food for the organisms. Rates of filtration and ingestion ofD. magnadeclinedwith increasing toxicant concentrations. The effective tetradifon concentrations inD. magnaat which feeding rate were reduced to 50% of that in controls (EC50) were 0.02 and 0.24 mg/L for filtration and ingestion rates respectively.

ISSN:0360-1234    

DOI:10.1080/03601239809373136

出版商:Taylor & Francis Group    

年代:1998

数据来源: Taylor

摘要:

The potential for dechlorinating 2,4‐dichlorophenoxyacetic acid (2,4‐D) and 2,4,5‐trichlorophenoxyacetic acid (2,4,5‐T) in soil with a consortium showing stable dechlorinating activity was investigated. The effects of adding electron donors and/or acceptors under three anaerobic reducing conditions was compared. Results show that both 2,4‐D and 2,4,5‐T dechlorination rates were enhanced in methanogenic conditions, delayed in sulfate‐reducing conditions, and inhibited in denitrifying conditions. Also under the same three conditions dechlorination was be enhanced by the addition of lactate, pyruvate, and acetate, delayed by the addition of manganese oxide and vitamin B12, and inhibited by the addition of ferric chloride. Response to treatment with such microbial inhibitors as bromoethane sulfonic acid (BESA), vancomycin, and molybdate suggests that the major bacteria involved in 2,4‐D and 2,4,5‐T dechlonnation is methanogen followed joined by sulfate‐reducing bacteria and eubacteria.

ISSN:0360-1234    

DOI:10.1080/03601239809373137

出版商:Taylor & Francis Group    

年代:1998

数据来源: Taylor

摘要:

The wood charcoal treated by 1N HNO3(WCT) was used to remove toxic chlorinated pesticide lindane (γ‐HCH) residue from water by the sorption process. The continuously mixed batch reactors (CMBR) were used to study the effect of system parameters, such as initial sorbate concentration, sorbent size, and sorbent dose on the sorption equilibrium time of lindane by WCT. Using a rational approach an appropriate value of the equilibrium time was determined. The assessed equilibrium time from such an approach was found to be less than the value obtained by rough estimate which is commonly adopted in practice. The co‐solutes or co‐sorbates, such as DDT and pentachlorophenol (PCP) imparted a marked decrease in sorption of lindane, whereas trichlorophenol (TCP) did not affect the removal pattern. WCT showed a preferential sorption of (i) DDT > lindane > α‐HCH > β‐HCH and (ii) PCP > lindane > TCP. At a concentration ≥ 20 mg/l of fertilizers, both urea and single super phosphate (SSP) significantly affected the removal of lindane. However, the effect was relatively higher by SSP than by urea.

ISSN:0360-1234    

DOI:10.1080/03601239809373138

出版商:Taylor & Francis Group    

年代:1998

数据来源: Taylor

ISSN:0360-1234    

DOI:10.1080/03601239809373133

出版商:Taylor & Francis Group    

年代:1998

数据来源: Taylor