The characteristics of nitrate removal by the psychrotolerant denitrifying bacterium Acinetobacter johnonii DBP-3, isolated from a low-temperature eutrophic body of water

A psychrotolerant denitrifying bacterial strain, DBP-3, was isolated from a eutrophic body of water by low-temperature-oriented acclimation culture. Based on its morphologicalandbiochemicalcharacteristics and 16S rDNA gene sequence, the bacterium was identified as belonging to the genus Acinetobacter and closely related to A. johnonii. The satisfactory growth of DBP-3 was observed at 10–30°C and pH 7–9. Strain DBP-3 was able to utilize three types of carbon sources (sodium acetate > sodium citrate > glucose) to support growth and denitrification. DBP-3 grew faster, but with lower nitrate removal efficiency and higher nitrite accumulation, under aerobic conditions than under anoxic conditions. DBP-3 was extremely susceptible to tetracycline and rifampicine and less sensitive to ampicillin and penicillin. The growth of DBP-3 was significantly affected by Hg (II), Cr (VI), Pb (II), Cd (II), and As (III) at 0.32, 0.63, 1.25, 2.5, and 25.0 mg L^?1, respectively. Interestingly, chromium (VI) significantly promoted DBP-3 growth at concentrations lower than 0.32 mg L^?1. These data may be helpful to support the use of strain DBP-3 in the purification of eutrophic water bodies at low temperatures.     

Characterization of distribution of pesticide residues in crop units

The characteristic features of distribution of pesticide residues in crop units and single sample increments were studied based on more than 19,000 residue concentrations measured in root vegetables, leafy vegetables, small-, medium- and large-size fruits representing 20 different crops and 46 pesticides. Log-normal, gamma and Weibull distributions were found to provide the best fit for the relative frequency distributions of individual residue data sets. The overall best fit was provided by lognormal distribution. The relative standard deviation of residues (CV) in various crops ranged from 15–170%. The 100–120 residue values being in one data set was too small to identify potential effects of various factors such as the chemical and physical properties of pesticides and the nature of crops. Therefore, the average of CV values, obtained from individual data sets, were calculated and considered to be the best estimate for the likely variability of unit crop residues for treated field (CV = 0.8) and market samples (CV = 1.1), respectively. The larger variation of residues in market samples was attributed to the potential mixing of lots and varying proportion of non-detects. The expectable average variability of residues in composited samples can be calculated from the typical values taking into account the sample size.     

An evaluation of lead concentrations in imported hot sauces

In the last decade, the U.S. Food and Drug Administration (FDA) has issued several warnings and recalls for food products that exceed FDA standards for lead. Products containing chili peppers and salt were often suspected as sources of lead contamination, and included items such as candy that are routinely investigated. However, products such as hot sauces that contain similar ingredients have not been the focus of evaluations. This study quantified lead concentrations in imported hot sauces, evaluated product compliance to existing United States standards, and calculated potential dietary lead exposure for children using the Integrated Exposure Uptake Biokinetic Model. Finally, recommendations for reducing the risk of lead exposure from hot sauces are provided. Twenty-five (25) bottles of imported hot sauces manufactured in Mexico and South America were purchased in Clark County, Nevada. All hot sauces were analyzed for lead concentrations, pH, and leaded packaging. Hot sauces were analyzed by inductively coupled plasma mass spectrometry and packaging was analyzed using x-ray fluorescence technology. Four brands of hot sauces (16%) exceeded 0.1 ppm lead, the current FDA action level for lead in candy. Hot sauces with lead concentrations >0.1 ppm lead contained salt and were manufactured in Mexico. Subsequent analysis of additional lots of hot sauces exceeding 0.1 ppm lead revealed inconsistent lead concentrations between and within manufacturer lots. The lead concentrations of the plastic hot sauce lids ranged from below the limit of detection to 2,028 ppm lead. There was no association between lead concentrations in hot sauces and pepper type. These results indicate the need for more rigorous screening protocols for products imported from Mexico, the establishment of an applicable standard for hot sauce, and resources to allow for the enforcement of existing food safety policies. The data reported herein represent the first known investigation of lead concentrations in hot sauces.     

Development,validation, and application of a method for the GC-MS analysis of fipronil and three of its degradation products in samples of water,soil, and sediment

A method for the identification and quantification of pesticide residues in water, soil, and sediment samples has been developed, validated, and applied for the analysis of real samples. The specificity was determined by the retention time and the confirmation and quantification of analyte ions. Linearity was demonstrated over the concentration range of 20 to 120 µg L^?1, and the correlation coefficients varied between 0.979 and 0.996, depending on the analytes. The recovery rates for all analytes in the studied matrix were between 86% and 112%. The intermediate precision and repeatability were determined at three concentration levels (40, 80, and 120 µg L^?1), with the relative standard deviation for the intermediate precision between 1% and 5.3% and the repeatability varying between 2% and 13.4% for individual analytes. The limits of detection and quantification for fipronil, fipronil sulfide, fipronil-sulfone, and fipronil-desulfinyl were 6.2, 3.0, 6.6, and 4.0 ng L^?1 and 20.4, 9.0, 21.6, and 13.0 ng L^?1, respectively. The method developed was used in water, soil, and sediment samples containing 2.1 mg L^?1 and 1.2% and 5.3% of carbon, respectively. The recovery of pesticides in the environmental matrices varied from 88.26 to 109.63% for the lowest fortification level (40 and 100 µg kg^?1), from 91.17 to 110.18% for the intermediate level (80 and 200 µg kg^?1), and from 89.09 to 109.82% for the highest fortification level (120 and 300 µg kg^?1). The relative standard deviation for the recovery of pesticides was under 15%.     

Effect of ozonization in degradation of trifluralin residues in aqueous and food matrices

Abstract

This study investigates the oxidation of trifluralin residues during ozonation in aqueous and food matrices (tomato). Domestic ozonation equipment with average production of 23.9?mg O₃ L^?1 h^?1 was used in the tests. Modern chromatographic systems (SPME-GC-IT/MS/MS and QuEChERS-GC-IT/MS/MS) were applied for extraction and detection of trifluralin residue in fortified samples of ultrapure water, tap water, superficial water and tomato fruit. The samples were submitted to the ozonation process during 0, 5, 10 and 20?min. Treatment at 5?min was able to degrade 71.5% of herbicide trifluralin in surface water. The removal (%) in ultrapure water reached 83.4% after 20?min of ozonation. The degradation of trifluralin in fortified tomato samples (0.025–0.1?mg kg^?1) were conducted with ozonation at 20?min, and it ranged from 84.4 to 92.7%. After treatment, levels of trifluralin in tomato remained within the established MRLs to EU, USEPA and ANVISA (Brazil). The data provided evidence that ozone is effective for removing trace trifluralin from water and foods.     

Induction of hepatic drug metabolizing enzymes in mammals by pesticides: A review

Abstract

The induction of drug metabolizing enzymes in mammals is summarized including both enzymes of the cytochrome P‐450‐dependent microsomal mixed function oxidase system and glutathione S‐transferases. Particular emphasis is placed on the role of pesticides as inducers, the early work being summarized while investigations carried out at North Carolina State University are considered in greater detail. Finally, the possible significance of induction is considered.     

Evidence of degradation of polybrominated biphenyls in soil samples from michigan

Abstract

Soil samples obtained from the former polybrominated biphenyls (PBB) manufacturing site in Michigan were analyzed by gas chromatography and gas chromatography with mass spectrometric detection. The results indicate significant degradation of the PBB residue in the soil sample. The soil sample with the highest concentration of PBB has the greatest degree of degradation. Principal degradation products include 2,3’,4,4’,5‐pentabromo‐biphenyl, 2,2’,4,4’,5‐pencabromobiphenyl and two unidentified tetrabromobiphenyls.

The degradation pattern observed supports a photochemical decomposition mechanism. These degraded residues may be more toxic than the original Firemaster residues. The implications of the results are discussed.     

Validation of Models for Predicting Formaldehyde Concentrations in Residences due to Pressed-Wood Products

This paper describes a laboratory project to assess the accuracy of emission and indoor air quality models to be used in predicting formaldehyde (HCHO) concentrations in residences due to pressed-wood products made with urea-formaldehyde bonding resins. The products tested were partlcleboard underlayment, hardwood- plywood paneling and medium-density fiberboard (mdf). The products were initially characterized in chambers by measuring their formaldehyde surface emission rates over a range of formaldehyde concentrations, air exchange rates and two combinations of temperature and relative humidity (23° C and 5 0% RH; 26°C and 60% RH). They were then installed in a two-room prototype house in three different combinations (underlayment flooring only; underlayment flooring and paneling; and underlayment flooring, paneling, and mdf). The equilibrium formaldehyde concentrations were monitored as a function of air exchange rate. Particleboard underlayment and mdf, but not paneling, behaved as the emission model predicted over a large concentration range, under both sets of temperature and relative humidity. Good agreement was also obtained between measured formaldehyde concentrations and those predicted by a mass-balance indoor air quality model.     

Determination of Room Temperature OH Rate Constants for Acetylene,Ethylene Dichloride,Ethylene Dibromide,p-Dichlorobenzene and Carbon Disulfide

A relative rate procedure was used to measure hydroxyl rate constants at room temperature in the presence of oxygen. The photolysis of methyl nitrite in the presence of nitric oxide was used to generate OH radicals. The rate of loss of the test compounds was measured relative to that of ethane (k_OH = 2.74 × 10^-13 cm³ molec^-1 s^-1). The rates obtained at 297 ± 2 K are: acetylene = (7.8 ± 1.6) × 10^-13 cm³ molec^-1 s^-1,1,2-dichloroethane (2.8 ± Q.6) × 10^-13 cm³ molec^-1 s^-1, 1,2-dibromoethane (2.4 ± 0.5) × 10^-13 cm³ molec^-1 s^-1, p-dichlorobenzene (4.3 ± 0.9) × 10^-13 cm³ molec^-1 s^-1 and carbon disulfide (29 ± 6) × 10^-13 cm³ molec^-1 s^-1. Under a proposed EPA rule, this OH rate determination procedure could be used to determine if a given volatile organic will be subject to control for reduction of photochemical ozone.     

A Management Systems Review of the Superfund RI/FS: Opportunities for Streamlining

The Management Systems Review is an important component of EPA’s quality assurance program. MSRs enable managers to assess the effectiveness of environmental data operations and the quality assurance/ quality control activities designed to ensure that the results are of the expected quality. These reviews inform managers about aspects of the environmental data operation that are working well and those which may warrant some improvement. A recent review of the Superfund remedial investigation/feasibility study (RI/FS) has shown that the MSR is an excellent tool for providing a systematic definition of complex environmental data operations and for enabling a thorough analysis of these operations. The MSR utilized information gathered from interviews of Regional staff and management and from case studies of recently completed RI/FSs. The findings indicated that environmental data play an important role in most RI/FS decisions and that thorough and structured scoping is critical to the effectiveness of the RI/ FS. Analysis of the RI/FS process using a comprehensive flow model identified several opportunities for changes that may increase efficiency in data collection and the reliability of RI/FS decisions. These changes provide for more effective scoping activities, a streamlined feasibility study, and increased use of treatability studies during the RI. A pilot demonstration of these process changes is being planned for a Regional RI/FS.