Assessment of the reproductive and developmental toxicity of pesticide/fertilizer mixtures based on confirmed pesticide contamination in California and Iowa groundwater

Pesticides and fertilizers, as used in modern agriculture, contribute to the overall low-level contamination of groundwater sources. In order to determine the potential of pesticide and fertilizer mixtures to produce reproductive or developmental toxicity at concentrations up to 100 x the median level found in groundwater, we prepared and studied two mixtures of pesticides and a fertilizer (ammonium nitrate). One mixture containing aldicarb, atrazine, dibromochloropropane, 1,2-dichloropropane, ethylene dibromide, and simazine plus ammonium nitrate was considered to be a representative of groundwater contamination in California (CAL). The other, containing alachlor, atrazine, cyanazine, metolachlor, metribuzin, and ammonium nitrate, simulated groundwater contamination in Iowa (IOWA). Each mixture was administered in the drinking water of either Swiss CD-1 mice during a Reproductive Assessment by Continuous Breeding study or pregnant Sprague-Dawley rats (gd 6-20) at three dose levels (1x, 10x, and 100x) where 1x was the median concentration of each pesticide component as determined in the groundwater surveys in California or Iowa. Unlike conventional toxicology studies, the purpose of this study was to evaluate the health effects of realistic human concentrations. Thus, the testing concentrations are probably well below the maximally tolerated dose. Propylene glycol was used as the solubilizer for the pesticides in drinking water formulations in both studies. In the reproductive study, neither mixture caused any clinical signs of toxicity, changes in food or water consumption, or body weight in either F0 or F1 mice at doses up to 100x the median groundwater concentrations. There were no treatment-related effects on fertility or any measures of reproductive performance of either the F0 or the F1 generation mice exposed to either CAL or IOWA at up to 100x. Similarly, measures of spermatogenesis, epididymal sperm concentration, percentage motile sperm, percentage abnormal sperm, and testicular and epididymal histology were normal. In the developmental study, CAL- or IOWA-exposed females did not exhibit any significant treatment-related clinical signs of toxicity. No adverse effects of CAL or IOWA were observed for measures of embryo/fetal toxicity, including resorptions per litter, live litter size, or fetal body weight. CAL or IOWA did not cause an increased incidence of fetal malformations or variations. In summary, administration of these pesticide/fertilizer mixtures at levels up to 100-fold greater than the median concentrations in groundwater supplies in California or Iowa did not cause any detectable reproductive (mice), general, or developmental toxicity (rats).     

Correlation analysis of pesticide use data and cancer incidence rates in California counties

California, the leading agricultural state in the United States, has maintained a population-based cancer registry since 1988, and it also maintains a comprehensive, state-wide pesticide reporting system. Data on cancer incidence and pesticide use reporting are available, by county, for all 58 counties in California. Average annual age-adjusted cancer incidence rates (1988-1992), on a county-, sex-, and race/ethnicity-specific basis, were obtained from the California Cancer Registry (CCR), which maintains the population-based cancer registry throughout California. Pesticide use data (i.e., pounds of active ingredient applied annually in each county) were obtained from the California Department of Pesticide Regulation for 1993. Investigators used Pearson product-moment correlation coefficients (r) to correlate age-adjusted incidence rates for selected cancers with the use data for selected pesticides. For most sex- and race/ethnicity-specific groups, the correlation coefficients were very close to zero or negative in sign, indicating no correlation between pesticide use and cancer incidence. There were, however, several exceptions, particularly in Hispanic males for whom the following correlations were observed: leukemia and atrazine (r=.40), leukemia and 2,4-dichlorophenoxyacetic acid (r=.41), leukemia and captan (r=.46), atrazine and brain cancer (r=.54), and atrazine and testicular cancer (r=.41). For black males, we observed the following: atrazine and prostate cancer (r=.67) and Captan and prostate cancer (r=.49). In females, only a few of the correlations were elevated. Although most of the correlations examined in this analysis were not elevated, several of those in the Hispanic and black male populations were. These segments of the population have traditionally been employed as farm workers in California and have had the greatest potential for exposure to pesticides. This was an ecological study for which no data about exposure to pesticides at the individual level were available for analysis. In addition, no latency period was allowed between potential exposure and diagnosis with cancer. However, the results obtained in two minority groups who represented the majority of farm workers in the fields suggested that additional research studies, in which more rigorous study designs are used, should be conducted in those groups.     

室内模拟BPRB修复阿特拉津污染地下水

设计了新型生物可渗透反应墙(BPRB)用于处理被污染的地下水。以阿特拉津为污染物,装填固定有阿特拉津降解菌(Pseudomonas W4)的磷酸化聚乙烯醇(PPVA)生物活性材料介质,前半部分以草炭土-PPVA/砂子为填料,以长期稳定地释放C、P;后半部分以珍珠岩-PPVA/砂子为填料,消耗草炭土-PPVA释放的C、P。选择V(PPVA生物活性材料)∶V(砂子)=1∶1的比例安装BPRB。在BPRB内设置曝气井,供氧方式为连续空气曝气,整个BPRB内DO质量浓度大于3 mg/L。BPRB模拟槽共运行140 d,累计进水1 213.6 L,共去除阿特拉津(19.35±1.00)g,出水中始终未检出阿特拉津。试验结果表明,在不额外添加碳源、磷源的条件下,BPRB能够长期稳定修复阿特拉津污染地下水。     

Immobilized liposome chromatography for studies of protein-membrane interactions and refolding of denatured bovine carbonic anhydrase

Seasonal variations of pesticide residues in surface waters and ground waters of the Imathia area of Central Mecedonia (N. Greece) were determined for the period from May 1996 to April 1997. The sampling cruises included eight sites in rivers Aliakmon, Loudias, Tripotamos, Arapitsa and Canal-66, seven water springs in the mountain Vermion, seven rainfall water collection stations and one hundred underground points. Solid-phase extraction disks followed by gas chromatographic techniques with flame thermionic detection, electron capture detection and mass-selective detection were used for the monitoring of various pesticides their transformation products in environmental waters. The most commonly encountered pesticides in underground waters, were alachlor, atrazine, desethylatrazine (DEA), metolachlor, molinate, propanil, simazine, carbofuran, diazinon and parathion methyl. The above compounds including propazine, trifluralin, malathion, parathion ethyl, lindane, alpha-benzene hexachloride (alpha-BHC), beta-BHC, 4,4'-DDE and heptachlor were determined in river waters. The higher concentrations in underground waters were measured during the period from May to August, 1996, following seasonal application and diminished significantly during the autumn and winter. Water pollution by triazine and chloroacetanilides was highest in the estuarine areas; showing that many of these compounds are transported significant distances from their application sites. The major inputs of atrazine, alachlor, simazine and metolachlor occurred in May and June just after their application. Atrazine, DEA, diazinon and metolachlor were also detected in spring waters at concentration levels below 0.006 microgram/l. Finally, atrazine, DEA, carbofuran, simazine, diazinon, parathion ethyl and parathion methyl were detected in rainfall water samples collected in the agricultural area of Imathia (central part of the plain).     

Internet and healthcare in Brazil: the role of the Working Group for Healthcare (GT Saúde)

The development of a disposable amperometric immunomigration sensor for the detection of triazine pesticides in real samples is presented. Thick film electrodes printed on PVC were used as strip-type transducers. Monoclonal antibodies against atrazine and terbutylazine served as biorecognition element. For the generation and amplification of the signal, hapten-tagged liposomes entrapping ascorbic acid as a marker molecule were chosen. A capillary gap and a wicking filter membrane strip served as migration zone. For signal detection on a graphite electrode, liposomes were lysed by Triton X-100 and the released ascorbic acid was quantified at a potential of + 300 mV vs printed Ag/AgCl. Signal response time was 1-3 min, and sensitivity of measurements in tap water was below 1 microgram l-1 of atrazine and terbutylazine. Atrazine determinations in soil extracts correlated well with standard procedures based on ELISA and HPLC.     

Atrazine chlorohydrolase from Pseudomonas sp. strain ADP: gene sequence, enzyme purification, and protein characterization

Pseudomonas sp. strain ADP metabolizes atrazine to carbon dioxide and ammonia via the intermediate hydroxyatrazine. The genetic potential to produce hydroxyatrazine was previously attributed to a 1.9-kb AvaI DNA fragment from strain ADP (M. L. de Souza, L. P. Wackett, K. L. Boundy-Mills, R. T. Mandelbaum, and M. J. Sadowsky, Appl. Environ. Microbiol. 61:3373-3378, 1995). In this study, sequence analysis of the 1.9-kb AvaI fragment indicated that a single open reading frame, atzA, encoded an activity transforming atrazine to hydroxyatrazine. The open reading frame for the chlorohydrolase was determined by sequencing to be 1,419 nucleotides and encodes a 473-amino-acid protein with a predicted subunit molecular weight of 52,421. The deduced amino acid sequence matched the first 10 amino acids determined by protein microsequencing. The protein AtzA was purified to homogeneity by ammonium sulfate precipitation and anion-exchange chromatography. The subunit and holoenzyme molecular weights were 60,000 and 245,000 as determined by sodium dodecyl sulfate-polyacrylamide gel electrophoresis and gel filtration chromatography, respectively. The purified enzyme in H2(18)O yielded [18O]hydroxyatrazine, indicating that AtzA is a chlorohydrolase and not an oxygenase. The most related protein sequence in GenBank was that of TrzA, 41% identity, from Rhodococcus corallinus NRRL B-15444R. TrzA catalyzes the deamination of melamine and the dechlorination of deethylatrazine and desisopropylatrazine but is not active with atrazine. AtzA catalyzes the dechlorination of atrazine, simazine, and desethylatrazine but is not active with melamine, terbutylazine, or desethyldesisopropylatrazine. Our results indicate that AtzA is a novel atrazine-dechlorinating enzyme with fairly restricted substrate specificity and contributes to the microbial hydrolysis of atrazine to hydroxyatrazine in soils and groundwater.     

Competitive Sorption of Pesticides onto Treated Wood Charcoal and the Effect of Organic and Inorganic Parameters on Adsorption Capacity

This paper presents competitive sorption of coexisting pesticides onto treated wood charcoal and describes the effect of various water quality parameters, viz., pH, ionic strength, chloride concentration, presence of calcium and magnesium, fertilizers, humic acid, polyacrylic acid, and also the effect of coexisting pesticides on the sorption of endosulfan onto treated wood charcoal. The coexisting pesticides were found to hinder the performance of wood charcoal in removing endosulfan. Competitive uptake study revealed that endosulfan occupies more sites followed by atrazine and monocrotophos. Solubility in water could be one of the major reasons for this preferential order. The presence of humic acid was found to show much more significant influence on the performance of wood charcoal than the presence of polyacrylic acid. Among fertilizers, single superphosphate was found more influential. Most of it, among the other reasons, could be due to the competition of the coexisting molecules for the available adsorption sites on wood charcoal. Other parameters have resulted in some fluctuations in performance, but the effects are not significant. Endosulfan removal efficiency faltered at higher pH values, and ionic species did not affect the sorption as endosulfan is nonionic under neutral conditions.     

Occurrence of pesticides in Danish shallow ground water

Shallow ground water from four different catchment areas, two sandy and two clayey locations, were investigated for content of pesticides and -degradation products. The samples were taken from screens in extraction wells placed from 1.5 to 5 meters below surface 46 different compounds were included in the study, and the analysis were performed with liquid chromatography mass spectrometry (LC-MS) with detection limits below 0.01 microgram/L. In total more than 300 samples were analysed and the most frequently found compounds being atrazine and its degradation products, bentazone, MCPA, metamitron, isoproturon and simazine. 23 out of the 46 compounds were detected in one or more samples. Four different sulfonylurea herbicides were included in the study as they to some extent have substituted phenoxyacid herbicides in agricultural practice and in much lower dosage. Sulfonylurea herbicides did not occur in any samples.     

Rapid atrazine mineralisation in soil slurry and moist soil by inoculation of an atrazine-degrading Pseudomonas sp. strain

The evaluation of pesticide-mineralising microorganisms to clean-up contaminated soils was studied with the widely applied and easily detectable compound atrazine, which is rapidly mineralised by several microorganisms including the Pseudomonas sp. strain Yaya 6. The rate of atrazine removal was proportional to the water content of the soil and the amount of bacteria added to the soil. In soil slurry, 6 mg atrazine kg soil-1 was eliminated within 1 day after application of 0.3 g dry weight inoculant biomass kg soil-1 and within 5 days when 0.003 g kg soil-1 was used. In partially saturated soil (60% of the maximal water-holding capacity) 15 mg atrazine kg soil-1 was used. In unsaturated soil, about 60% [U-ring-14C] atrazine was converted to 14CO2 within 14 days. Atrazine was very efficiently removed by the inoculant biomass, not only in soil that was freshly contaminated but also in soil aged with atrazine for up to 260 days. The bacteria exposed to atrazine in unsaturated sterile soil were still active after starvation period of 240 days: 15 mg newly added atrazine kg soil-1 was eliminated within 5 days.     

Evaluation of multiwavelength chromatograms for the quantification of mixtures of pesticides by high-performance liquid chromatography-diode array detection with multivariate calibration

Three multivariate calibration methods, partial least squares (PLS-1 and PLS-2) and principal component regression, were applied to the simultaneous determination of the five pesticides iprodione, procymidone, chlorothalonil, folpet and triazophos by high-performance liquid chromatography with diode array detection. Such detection gives multiwavelength chromatograms from a single analysis of one sample. In this paper, calibration models at two different wavelengths were developed to resolve mixtures of five pesticides with overlapping chromatographic peaks. The first model, carried out at 220 nm as detector compromise wavelength, yielded satisfactory sensitivity for accurate estimation of the concentration of iprodione, procymidone, chlorothalonil and folpet and the second model, at 200 nm, was used for accurate estimation of triazophos. Both calibration models were evaluated using the chromatograms and first-derivative (1D) chromatograms by predicting the concentrations of independent test set samples. Finally, the proposed 1D calibration models were successfully applied to the determination of these pesticides in groundwater and soil samples. In all cases, the PLS-1 calibration method showed superior quantitative prediction ability than the PLS-2 or principal component regression methods.     

Multicriteria Analysis in an Irrigation District in Mexico

The Alto Rio Lerma Irrigation District, located in the state of Guanajuato in Mexico, is an agricultural area whose sustainability depends partially upon groundwater withdrawal for crop irrigation. Because of high pumping demands and current land-management practices, groundwater levels have declined severely, resulting in aquifer overdraft. In order to analyze economic, environmental, and water use problems in this region, 12 potential cropping patterns were generated for different groundwater withdrawals using linear programming. Then, simulation of the agricultural system was performed using GLEAMS to estimate the amounts of water, nitrate, and pesticides in both runoff and percolation for each cropping pattern. Pumping costs and an aquifer exploitation coefficient account for the economic and environmental impacts of aquifer overdraft. Finally, the Range of Value Method (multicriteria method) was applied to rank and identify the best cropping pattern. The results show the best alternative for effectively balancing environmental with economic considerations was the farming practice, consisting of land leveling, growing vegetables such as red tomato, and controlled groundwater withdrawals to preserve aquifer sustainability.     

Older persons'' preferences for site of treatment in acute illness

OBJECTIVES: The objective of this pooled analysis was to examine whether exposure to DDT was associated with the risk of non-Hodgkin's lymphoma among male farmers. METHODS: Data from three case-control studies from four midwestern states in the United States (Nebraska, Iowa, Minnesota, Kansas) were pooled to carry out analyses of 993 cases and 2918 controls. Information on use of agricultural pesticides and other risk factors was based on interviews. Non-farmers (people who had never lived or worked on a farm) were used as a reference category. RESULTS: There were 161 cases and 340 controls who reported use of DDT on animals or crops, or on both, yielding an odds ratio (OR) of 1.2 (95% confidence intervals (95% CI) 1.0 to 1.6). Farmers who had used DDT for > or = 15 years had an OR of 1.5 (95% CI 1.0 to 2.3). Adjustment for respondent status and use of other pesticides resulted in slightly reduced ORs. Analyses by the number of days of use a year was limited to the Nebraska data. The most notable increase was found among farmers who used DDT for > or = 5 days a year (OR 2.6, 95% CI 1.1 to 5.9); however, additional adjustment for use of organophosphates, phenoxyacetic acids, and the individual pesticides lindane, malathion, and atrazine reduced the ORs to 1.0, 0.9, 1.1, 1.6, and 1.9 respectively. CONCLUSIONS: No strong consistent evidence was found for an association between exposure to DDT and risk of non-Hodgkin's lymphoma. It seems that the excess risk initially found may be explained by use of other pesticides.     

Effects of Stormwater Infiltration on Quality of Groundwater Beneath Retention and Detention Basins

Infiltration of storm water through detention and retention basins may increase the risk of groundwater contamination, especially in areas where the soil is sandy and the water table shallow, and contaminants may not have a chance to degrade or sorb onto soil particles before reaching the saturated zone. Groundwater from 16 monitoring wells installed in basins in southern New Jersey was compared to the quality of shallow groundwater from 30 wells in areas of new-urban land use. Basin groundwater contained much lower levels of dissolved oxygen, which affected concentrations of major ions. Patterns of volatile organic compound and pesticide occurrence in basin groundwater reflected the land use in the drainage areas served by the basins, and differed from patterns in background samples, exhibiting a greater occurrence of petroleum hydrocarbons and certain pesticides. Dilution effects and volatilization likely decrease the concentration and detection frequency of certain compounds commonly found in background groundwater. High recharge rates in storm water basins may cause loading factors to be substantial even when constituent concentrations in infiltrating storm water are relatively low.     

Separation-free electrochemical immunosensor for rapid determination of atrazine

A separation-free electrochemical immunoassay method for the detection of the pesticide atrazine is described. The method developed is a competitive ELISA incorporating disposable screen printed horseradish peroxidase modified electrodes as the detector element in conjunction with single-use atrazine immuno-membranes. Screen printed carbon electrodes were prepared using carbon ink incorporating horseradish peroxidase. A monoclonal antibody for atrazine was immobilised onto Biodyne C membranes which were, in turn, placed over the electrode surface. The assay was based on competition for available binding sites between free atrazine and an atrazine-glucose oxidase conjugate prepared 'in-house'. In the presence of glucose, H2O2 formed by the conjugate was reduced by enzyme-channelling via the HRP electrode. The HRP was in turn re-reduced by a direct electron transfer mechanism at a potential of +50 mV Vs Ag/AgCl. Any H2O2 formed in the bulk solution by unbound atrazine-GOD conjugate was scavenged by excess catalase thus removing the requirement for a washing step. The performance of the method was compared with a commercial immunoassay kit for atrazine.     

Effect of preadsorbed background organic matter on granular activated carbon adsorption of atrazine

This study examines the effect of preadsorbed background organic matter (measured as dissolved organic carbon, DOC) on the granular activated carbon (GAC) adsorption of atrazine. Thirty-four experiments were conducted in batch contactors using organic-free laboratory water (< 0.1 mg/l DOC) and pilot-column GAC, preloaded with DOC for 3-20 weeks (equivalent to 4.3-32 mg DOC/g GAC). Freundlich isotherms were determined for adsorption of atrazine at initial concentrations from 10 to 1000 micrograms/l. The isotherm data indicate that GAC capacities for atrazine are only moderately reduced by preadsorbed DOC. At an initial concentration of 1000 micrograms/l atrazine, the GAC capacity for atrazine decreases by -1.0 mg atz/mg preadsorbed DOC. At an initial concentration of 10 micrograms/l atrazine, the GAC capacity for atrazine decreases by only -0.40 mg atz/mg preadsorbed DOC. For the pilot-column GAC preloaded with a maximum of 32 mg DOC/g GAC, the decrease in capacity for atrazine averages -33 +/- 13%.     

Biodegradation of atrazine by Agrobacterium radiobacter J14a and use of this strain in bioremediation of contaminated soil

We examined the ability of a soil bacterium, Agrobacterium radiobacter J14a, to degrade the herbicide atrazine under a variety of cultural conditions, and we used this bacterium to increase the biodegradation of atrazine in soils from agricultural chemical distribution sites. J14a cells grown in nitrogen-free medium with citrate and sucrose as carbon sources mineralized 94% of 50 microgram of [14C-U-ring]atrazine ml-1 in 72 h with a concurrent increase in the population size from 7.9 x 10(5) to 5.0 x 10(7) cells ml-1. Under these conditions cells mineralized the [ethyl-14C]atrazine and incorporated approximately 30% of the 14C into the J14a biomass. Cells grown in medium without additional carbon and nitrogen sources degraded atrazine, but the cell numbers did not increase. Metabolites produced by J14a during atrazine degradation include hydroxyatrazine, deethylatrazine, and deethyl-hydroxyatrazine. The addition of 10(5) J14a cells g-1 into soil with a low indigenous population of atrazine degraders treated with 50 and 200 microgram of atrazine g-1 soil resulted in two to five times higher mineralization than in the noninoculated soil. Sucrose addition did not result in significantly faster mineralization rates or shorten degradation lag times. However, J14a introduction (10(5) cells g-1) into another soil with a larger indigenous atrazine-mineralizing population reduced the atrazine degradation lag times below those in noninoculated treatments but did not generally increase total atrazine mineralization.     

Studies on the degradation of atrazine by bacterial communities enriched from various biotopes

Degradation of 14C-ring labeled atrazine (2-choloro-4-(ethylamino)-6-(isopropylamino)-s-triazine) by bacterial populations from soil, waters and activated sludges was investigated and compared with non-biological decomposition in sterile solutions. Within two weeks, 0.6% Cl-deethyl- and 0.1% Cl-deisopropylatrazine had been formed in sterile 0.02 M phosphate buffer, pH 7.2. In biodegradation studies, bacterial populations were enriched and incubated in media containing atrazine and high or low levels of nutrients. Nutrient supply had a strong effect on the fate of atrazine in bacterial cultures, whereas the origin of bacteria was of minor importance. In 31 of 33 mixed populations investigated, the herbicide was largely converted to unidentified compounds. Incubation with high levels of nutrients resulted in 17% to 57% of these compounds being constant after one and two weeks of incubation. In parallel experiments with low nutrient supply, the compounds were present in amounts of 7% to 57% after one week. The proportions of the unidentified compounds dropped within the second week of incubation, while atrazine reappeared correspondingly. The amounts of dealkylated metabolites generally did not exceed those of sterile solutions. The results indicate that atrazine is not degraded by bacteria but bound, thus simulating biodegradation. Evidence is presented that physicochemical decomposition of the herbicide is more significant than microbial degradation.     

Enhanced degradation of deethylatrazine in an atrazine-history soil of Iowa

The degradation of deethylatrazine (DEA), a major metabolite of atrazine, was studied by using radiotracers in soils with two different atrazine histories. DEA degradation was enhanced in soils which had received long-term exposure to atrazine (atrazine-history soil) compared with soils that had not received long-term atrazine exposure (no-history soil). After 60 days of incubation, mineralization of DEA to 14CO2 in the atrazine-history surface soil was twice that in the no-history surface soils, with 34% and 17% of the applied 14C-DEA as CO2, respectively. In surface soils, 25% of the applied 14C remained as DEA in the atrazine-history soil, compared with 35% in the no-history soil. Microbial plate counts indicated an increase in numbers of bacteria and fungi in soils incubated with DEA compared to control soils. No significant difference in total microbial respiration was seen among atrazine-history and no-history soils incubated with DEA, but DEA-treated soils had greater microbial respiration than untreated control soils after 6 days. A 14C-most-probable-number procedure was used to enumerate specific DEA degraders. A greater number of DEA degraders were indicated in atrazine-history subsurface soil compared with all other soils in this study (p < 0.05). From this study, it appears that an increase in microbial activity contributes to decreased persistence and increased degradation of DEA in soils that have had long-term exposure to atrazine at field application rates, compared to soils with no long-term exposure. Decreased persistence of this major metabolite of atrazine in atrazine-history soils is important in that there will be less available for movement in surface runoffs.     

Degradation of atrazine and 2,4-dichlorophenoxyacetic acid by mycorrhizal fungi at three nitrogen concentrations in vitro

Nine mycorrhizal fungi and free-living saprophytic microorganisms were tested for their ability to degrade two chlorinated aromatic herbicides at two herbicide concentrations and three nitrogen concentrations. Radiolabelled 2,4-dichlorophenoxyacetic acid (2,4-D) and 2-chloro-4-ethylamino-6-isopropylamino-s-triazine (atrazine) were used as substrates at concentrations of 1 and 4 mM. After 8 weeks, none of the cultures tested grew at 4 mM 2,4-D. However, when the 2,4-D concentration was reduced to 1 mM, Phanerochaete chrysosporium 1767 had the highest level of 2,4-D mineralization and degradation under all nitrogen conditions. All cultures tested grew at both atrazine concentrations. In all cases, the ericoid mycorrhizal fungus Hymenoscyphus ericae 1318 had the highest level of atrazine carbon incorporated into its tissue. In general, as the nitrogen concentration increased, the total herbicide degradation increased. All of the cultures, except for Rhizopogon vinicolor 7534 and Sclerogaster pacificus 9011, showed increased degradation at 4 mM compared with 1 mM atrazine. The ability to degrade these two herbicides thus appeared to be dependent on the fungus and the herbicide, with no correlation to fungal ecotype (mycorrhizal versus free living).     

Fe、C包覆金红石型TiO2可见光催化H2O2降解阿特拉津的研究

以Fe、C包覆金红石型TiO2(Fe-C-R)为光催化剂,以阿特拉津作模型污染物,研究了Fe-C-R可见光催化H2O2降解阿特拉津的反应特性。表明Fe-C-R能可见光催化H2O2降解阿特拉津,反应45 min,阿特拉津的降解率达98%;通过对反应体系的荧光光谱分析显示,阿特拉津的降解涉及羟基自由基(·OH)的产生与参与,并且与单纯的金红石型TiO2(R)降解阿特拉津的反应机理是不同的。