首页 | 本学科首页   官方微博 | 高级检索  
相似文献
 共查询到20条相似文献，搜索用时 93 毫秒
1.
Biological degradation rates of six pharmaceuticals and personal care products were examined in soil from a land application site and in adjacent soil with no prior history of effluent exposure. Microbial degradation rates were compared over 2 weeks under standing water or saturated conditions and draining conditions after having been saturated for 3 days. Biological degradation of 17??-estradiol exhibited rapid rates of biological degradation under both saturated and draining conditions. Half-lives for 17??-estradiol ranged from 1.5 to 4 days; 66?C97% was lost from the soils. Estriol showed a pattern of biological degradation in both saturated and draining conditions though the half-lives were longer (8.7?C25.9 days) than those observed for 17??-estradiol. Twenty-eight percent to 73% of estriol was lost over the 14 days treatment period. Estrone and 17??-ethinylestradiol exhibited slower rates of biological transformation under saturated and draining conditions. Half-lives for estrone ranged between 27.5 and 56.8 days with loss of at most 21%. 17??-ethinylestradiol exhibited half-lives of 22.6?C207 days. Half-life data for ibuprofen ranged from 30.4 to 1,706.4 days in this experiment. Losses of up to 17% were observed in draining soils. Triclosan loss was at most 10%, and half-lives were 70.9?C398.8 days. In all cases, soils that were draining from saturated conditions exhibited faster degradation rates than soils that remained saturated. Prior exposure of the soil to effluent did not always result in higher biological degradation rates.  相似文献   

2.
Atrazine and metolachlor degradation in subsoils   总被引：6，自引：0，他引：6  
Degradation of atrazine [2-chloro-4-etylamino-6-isopropylamino-1,3,5-triazine] and metolachlor [2-chloro-N-(2-ethyl-6-methylphenyl)-N-(2-methoxy-1-methylethyl)-acetamide] in sterile and non-sterile soil samples collected at two different soil depths (0-20 and 80-110 cm) and incubated under aerobic and anaerobic conditions was studied. Under aerobic conditions, the half-life of atrazine in non-sterile surface soil was 49 days. In non-sterile subsoil, the half-life of atrazine (119 days) was increased by 2.5 times compared in surface soils and was not statistically different from half-lives in sterile soils (115 and 110 days in surface soil and subsoil, respectively). Metolachlor degradation occurred only in non-sterile surface soil, with a half-life of 37 days. Under anaerobic conditions, atrazine degradation was markedly slower than under aerobic conditions, with a half-life of 124 and 407 days in non-sterile surface soil and non-sterile subsoil, respectively. No significant difference was found in atrazine degradation in both sterile surface soil (693 days) and subsoil (770 days). Under anaerobic conditions, degradation of metolachlor was observed only in non-sterile surface soil. Results suggest that atrazine degraded both chemically and biologically, while metolachlor degraded only biologically. In addition, observed Eh values of soil samples incubated under anaerobic conditions suggest a significant involvement of soil microorganisms in the overall degradation process of atrazine under anaerobic conditions.  相似文献   

3.
This work aims to study the degradation of estrone, 17??-estradiol, 17??-ethinylestradiol, and estriol under direct solar radiation, with an average irradiance value of 5.2?kWh/m2. Degradation at different temperatures (4??C, 20??C, and 30??C) was also tested in darkness. Individual solutions of the four estrogens were prepared and subjected to the conditions referred to above. The degradation for each compound was followed, after 7, 14, 21, 28, 35, 63, 91, and 126?days measuring the absorbance at the wavelength of 281?nm. The degradation of the four mixed estrogens was determined using capillary electrophoresis (CE), with a diode array detector and cholic acid, sodium salt plus sodium borate as a background buffer. The results showed no significant degradation rates on samples subjected to different temperatures. However, the results from CE analysis showed that, under direct solar radiation, after 126?days, the degradation rate varied between 75% and 100%. Also, the UV?CVis showed significant changes in the shape of UV?CVis spectra under direct solar radiation.  相似文献   

4.
Degradation of Cry1Ab protein from Bt transgenic rice was examined under both aerobic and flooded conditions in five paddy soils and in aqueous solutions. The hydrolysis rate of Cry1Ab protein in aqueous solutions was correlated inversely with the solution pH in the range of 4.0 to 8.0, and positively with the initial concentration of Cry1Ab protein. Rapid degradation of Cry1Ab protein occurred in paddy soils under aerobic conditions, with half-lives ranging from 19.6 to 41.3 d. The degradation was mostly biotic and not related to any specific soil property. Degradation of the Cry1Ab protein was significantly prolonged under flooded conditions compared with aerobic conditions, with half-lives extended to 45.9 to 141 d. These results suggest that the toxin protein, when introduced into a paddy field upon harvest, will probably undergo rapid removal after the field is drained and exposed to aerobic conditions.  相似文献   

5.
五氯酚在长期定位施肥土壤中的残留动态   总被引：1，自引：1，他引：0  
王诗生  卞永荣  王芳  杨兴伦  李忠佩  蒋新 《土壤》2009,41(3):442-447
研究好氧和厌氧条件下五氯酚 (PCP) 在长期不施肥 (CK),施无机肥尿素 (N),施有机肥 (OM)和无机有机肥配施 (N+OM) 4 种处理土壤中的残留动态.结果表明,无论在好氧或厌氧条件下,PCP 在土壤中的消解均遵循一级动力学方程.在好氧条件下,PCP 在 CK、N、OM 和 N+OM 4 种处理土壤中半衰期分别为 26.9、27.7、21.5、20.6 天,在厌氧条件下,PCP 的半衰期分别为 30.8、32.2、27.1、25.9 天.表明无论在好氧或厌氧条件下,长期单施有机肥或无机有机肥配施显著加速 PCP 在土壤中的消解,原因可能是长期单施有机肥或无机有机肥配施能显著提高土壤有机质含量和微生物活性,加速 PCP 在土壤中的消解.好氧条件下 PCP 的消解速率显著高于厌氧条件.  相似文献   

6.
Background and Main Features  The mineralization of eight organic chemicals (surfactants, substituted aromatic compounds, di(2-ethylhexyl)phthalate and phenanthrene) was examined in sludge-soil mixtures under aerobic, denitrifying and methanogenic conditions. Results and Discussion  Most of the chemicals were extensively or partially mineralized under aerobic conditions with mineralization half-lives between 1.5 and 12.5 days. Linear tridecyl tetra ethoxylate, di(2-ethylhexyl)phthalate and 2,4-dinitrophenol were also mineralized partially under denitrifying conditions. No mineralization of the chemicals was observed under methanogenic conditions, with the exception of a minor mineralization of linear tridecyl tetraethoxylate. Conclusion  This study indicates that the examined organic chemicals may be rapidly degraded in sludge-amended fields under aerobic conditions, and that some of the chemicals may also be degraded during denitrification. Recommendations and Outlook  When investigating the degradation of sludge-bound chemicals in soil, it is relevant to consider both aerobic and anaerobic soil regimes due to spatial and temporal variations in the redox conditions within sludge and soil. The approach presented in this article may be used for evaluation of the long-term fate of sludge-bound chemicals in soil.  相似文献   

7.
Methylation and demethylation of arsenic may change substantially the toxicity and mobility of arsenic in soils. Little is known about demethylation of organic arsenic species in organic soils. We incubated dimethylarsinic acid (DMA) and arsenobetaine (AsB) in soils and aqueous soil extracts from a forest floor and fen, in order to investigate demethylation processes. Incubations were conducted at 5°C in the dark under oxic or anoxic conditions. Arsenobetaine demethylated rapidly in all soil extracts with half-lives of 3.6–12 days, estimated from first order kinetic. Demethylation of DMA was relatively slow with half-lives of 187 and 46 days in the forest floor extracts and oxic fen extracts, respectively. In comparison, DMA was stable for 100 days in anoxic fen extracts. The apparent half-lives were much shorter in soils for DMA (1.3–12.6 days) and AsB (0.5–1.9 days) than in soil extracts, suggesting also irreversible AsB and DMA adsorption to soils beside demethylation. An unknown arsenic species and DMA were detected as metabolites of AsB demethylation. The results indicate rapid demethylation of AsB probably via the pathway AsB → Dimethylarsenoylacetate → DMA, followed up by slow demethylation of DMA → monomethylarsonic acid → inorganic As species.  相似文献   

8.
Spinosad is a bacterially derived insect control agent consisting of two active compounds, spinosyns A and D. The objective of this paper is to describe the environmental fate of spinosad in aquatic systems. To this end, several studies performed to meet regulatory requirements are used to study the fate and degradation in individual environmental media. Specifically, investigations of abiotic (hydrolysis and photolysis) and biotic (aerobic and anaerobic aquatic) processes are described. Understanding developed from the laboratory-based studies has been tested and augmented by an outdoor microcosm study. Understanding of aquatic fate is a building block for a complete environmental safety assessment of spinosad products (Cleveland, C. B.; Mayes, M. A.; Cryer, S. A. Pest Manag. Sci. 2001, 58, 70-84). From individual investigations, the following understanding of dissipation emerges: (1) Aqueous photolysis of spinosad is rapid (observed half-lives of <1 up to 2 days in summer sunlight) and will be the primary route of degradation in aquatic systems exposed to sunlight. (2) Biotic transformations contribute to spinosad's dissipation, but less so than photolysis; they will be of primary importance only in the absence of light. (3) Spinosad partitions rapidly (within a few days) from water to organic matter and soil/sediment in aquatic systems but not so rapidly as to replace sunlight as the primary route of dissipation. (4) Abiotic hydrolysis is relatively unimportant compared to other dissipation routes, except under highly basic (artificial) conditions and even then observed half-lives are approximately 8 months. Degradation pathways are understood are follows: (1) Degradation primarily proceeds by loss of the forosamine sugar and reduction of the 13,14-bond on the macrolide ring under aqueous photolytic conditions. (2) Degradation to several other compounds occurs through biotic degradation. Degradation under anaerobic conditions primarily involves changes and substitutions in the rhamnose ring, eventually followed by complete loss of the rhamnose ring. Degradation under aerobic conditions was more extensive (to smaller compounds) with the loss of both the forosamine and rhamnose sugars to diketone spinosyn aglycon degradates. (3) Hydrolytic degradation involves loss of the forosamine sugar and water and reduction on the macrolide ring to a double bond at the 16,17-position.  相似文献   

9.

Purpose

Understanding the effects of temperature and moisture on soil organic carbon (SOC) dynamics is crucial to predict the cycling of C in terrestrial ecosystems under a changing climate. For single rice cropping system, there are two contrasting phases of SOC decomposition in rice paddy soils: mineralization under aerobic conditions during the off-rice season and fermentation under anaerobic conditions during the growth season. This study aimed to investigate the effects of soil temperature and moisture on SOC decomposition under the aerobic and subsequently anaerobic conditions.

Materials and methods

Two Japanese paddy soils (Andisol and Inceptisol) were firstly incubated under four temperatures (±5, 5, 15, and 25°C) and two moisture levels (60 and 100% water-filled pore space (WFPS)) under aerobic conditions for 24 weeks. Then, these samples were incubated for 4 weeks at 30°C and under anaerobic conditions. Carbon dioxide (CO2) and methane (CH4) productions were measured during the two incubation stages to monitor the SOC decomposition dynamics. The temperature sensitivity of SOC was estimated by calculation of the Q10 parameter.

Results and discussion

The total CO2 production after the 24-week aerobic incubation was significantly higher in both soils for increasing soil temperature and moisture (P < 0.01). During the subsequent anaerobic incubation, total decomposed C (sum of CO2 and CH4 productions) was significantly lower in samples that had been aerobically incubated at higher temperatures (15 and 25°C). Moreover, CH4 production was extremely low in all soil samples. Total decomposed C after the two incubation stages ranged from 256.8 to 1146.1 mg C kg?1 in the Andisol and from 301.3 to 668.8 mg C kg?1 in the Inceptisol. However, the ratios of total decomposed C to SOC ranged from 0.29 to 1.29% in the Andisol and from 2.21 to 4.91% in the Inceptisol.

Conclusions

Both aerobic and anaerobic decompositions of SOC in two paddy soils were significantly affected by soil temperature and moisture. Maintaining optimal soil temperature and medium moisture during the off-rice season might be an appropriate agricultural management to mitigate CH4 emission in the following rice growth season. Although it is high in SOC content, Andisol has less biodegradable components compared to Inceptisol and this could be a probable reason for the distinct difference in temperature sensitivity of SOC decomposition between two paddy soils.
  相似文献   

10.
Summary The hydrolysis of fertilizer-grade solid and liquid ammonium polyphosphate (APP) was studied on an aluvial (Entisol, Typic Ustifluvent), a sodic (Entisol Aquic Ustifluvent), and a laterite (Oxisol, Aquox) soil under aerobic and anaerobic conditions. The hydrolysis rate was the fastest on laterite, intermediate on sodic, and slowest in the alluvial soil. Ammonium polyphosphate hydrolyzed more rapidly under anaerobic than under aerobic conditions. The hydrolysis of liquid ammonium polyphospahte was faster than that of solid ammonium polyphosphate in all soils. The half-life values for the polyforms of P in liquid ammonium polyphosphate ranged from 1.6 to 2.0 days under anaerobic and from 5.2 to 8.7 days under aerobic conditions. The corresponding values for solid ammonium polyphosphate were 3.9 to 9.2 days under anaerobic and 12.5 to 27.0 days under aerobic conditions.  相似文献   

11.
The size of the bacteria in different layers and horizons of an arable typical chernozem in the course of the microbial succession under aerobic and anaerobic conditions of incubation was studied. Bacteria with sizes of ??0.23 and ??0.38 ??m predominated under the aerobic conditions; in the anaerobic conditions, their sizes were ??0.17, ??0.23, and ??0.38 ??m. Thus, under anaerobic conditions, the number of bacteria becomes greater at the expense of the increase of their fine forms. The bacterial biomass was the highest (16 ??g/g soil) in the B horizon under the anaerobic conditions, probably, due to the greater number of fine bacterial forms developing in these conditions in nature. In the A horizon under the anaerobic conditions, the bacterial biomass was somewhat lower (12 ??g/g soil) probably because of the high bacterial diversity there. All the soil bacteria were proved to have a size ranging within ??0.43-0.17 ??m.  相似文献   

12.
The relationships between the denitrification capacities of 17 surface soils and the amounts of total organic carbon, mineralizable carbon, and water-soluble organic carbon in these soils were investigated. The soils used differed markedly in pH, texture, and organic-matter content. Denitrification capacity was assessed by determining the N evolved as N2 and N2O on anaerobic incubation of nitrate-treated soil at 20°C for 7 days, and mineralizable carbon was assessed by determining the C evolved as CO2 on aerobic incubation of soil at 20°C for 7 days. The denitrification capacities of the soils studied were significantly correlated (r = 0·7771) with total organic carbon and very highly correlated (r = 0·9971) with water-soluble organic carbon or mineralizable carbon. The amount of nitrate N lost on anaerobic incubation of nitrate-treated soils for 7 days was very closely related (r = 0·99971) to the amount of N evolved as N2 and N2O.The work reported indicates that denitrification in soils under anaerobic conditions is controlled largely by the supply of readily decomposable organic matter and that analysis of soils for mineralizable carbon or water-soluble organic carbon provides a good index of their capacity for denitrification of nitrate.  相似文献   

13.
The microbiological degradation of a mixture of alkylpyridines in groundwater maintained under aerobic and anaerobic conditions was examined. A marked difference was observed between the aerobic and anaerobic degradation rates. In the presence of a soil inoculum and under aerobic conditions, the residual alkylpyridine concentrations generally approached zero concentration within 10 to 31 days of incubation, whereas under anaerobic conditions the concentrations of residual alkylpyridines only decreased between 40 and 80% over a 33 day incubation period. Biodegradation rates under aerobic conditions were greatly affected by the specific ring substitution of structural isomers within a given weight class. A similar effect was not observed for anaerobic degradation rates.  相似文献   

14.
Photodegradation of four pharmaceuticals (i.e. carbamazepine, ibuprofen, ketoprofen and 17α-ethinylestradiol) in aqueous media was studied using a solar light simulator (Xe lamp irradiation) and sunlight experiments. These experiments were carried out in river and seawater and compared to distilled water. The latter was used to evaluate the direct photodegradation pathways. Irradiation time was up to 400 min and 24 days for the solar light simulator and sunlight assays, respectively. Pharmaceutical photodegradation followed a first-order kinetics and their half-lives calculated in every aqueous matrix. Moreover, the sensitizing effect of DOC was evaluated by comparison with the kinetics obtained in distilled waters. Ketoprofen was rapidly transformed via direct photolysis in all the waters under both sunlight (t 1/2?=?2.4 min) and simulated solar light simulator test (t 1/2?=?0.54 min). Under xenon lamp radiation, ibuprofen and 17α-ethinylestradiol were photodegraded at moderate rate with half-lives from 1 to 5 h. Finally, carbamazepine had the lowest photodegradation rate (t 1/2?=?8–39 h) attributable to indirect photodegradation. Indeed, its elimination was strongly dependent on the DOC concentration present in solution. Finally, several ketoprofen photoproducts were identified and plotted against solar light simulator irradiation time. Accordingly, the photodegradation pathway of ketoprofen was postulated.  相似文献   

15.
Pharmaceuticals and personal care products (PPCPs) can reach soil and aquatic environments through land application of wastewater effluent and agricultural runoff. The objective of this research was to assess the fate of PPCPs at field scale. PPCPs were measured systematically in a wastewater treatment plant (WWTP), and in soil and groundwater receiving treated effluent from the WWTP. A land application site in West Texas was used as the study site; it has received treated wastewater effluent from the WWTP for more than 70 years in order to remove additional nutrients and irrigate non-edible crops. Target compounds (estrone, 17??-estradiol, estriol, 17??-ethynylestradiol, triclosan, caffeine, ibuprofen, and ciprofloxacin) in wastewater, sewage sludge, soil, and groundwater were determined using HPLC/UV with qualitative confirmatory analyses using GC/MS. Samples were collected quarterly over 12 months for wastewater and sludge samples and over 9 months for soil and groundwater samples. Results indicated that concentrations of PPCPs in wastewater influent, effluent, sludge solid phase, and sludge liquid phase were in the range of non-detected (ND)-183 ??g/L, ND-83 ??g/L, ND-19 ??g/g, and ND-50 ??g/L, respectively. Concentrations in soil and groundwater samples were in the range of ND-319 ng/g and ND-1,745 ??g/L, respectively. GC/MS confirmation data were consistent with the results of HPLC/UV analyses. Overall, data indicate that PPCPs in the wastewater effluent from the WWTP transport both vertically and horizontally in the soil, and eventually reach groundwater following land application of the effluent.  相似文献   

16.
Ethion, a highly persistent insecticide in soil, is extensively used in tea cultivation in the tropics. The studies on the environmental impact of ethion in tea soil ecosystems are scanty. Silty loam and sandy loam soils from tea fields of Dooars (Typic Uderthents) and Hill (Typic Dystrudepts), respectively, were investigated for the degradation and effect of ethion application on soil microbial and biochemical variables under controlled laboratory conditions. Ethion degraded faster in the Hill soil than in the Dooars soil. Higher temperature (30°C) aided in faster degradation due to the increased microbial activity in the soils. Ethion application at field rate (FR) had lower half-lives (70 days at 20°C and 42.3 days at 30°C for Dooars soil; 65.4 days at 20°C and 39 days at 30°C for Hill soil) than at ten times FR (10FR; 75.2 days at 20°C and 44.2 days at 30°C for Dooars soil; 70 days at 20°C and 41.8 days at 30°C for Hill soil). Soil microbial biomass carbon, ergosterol content, fluorescein diacetate hydrolyzing and β-glucosidase activities declined in all the treatment combinations up to day 60 for both FR and 10FR doses at 20°C, irrespective of the soil types. At 30°C, the decreasing trend was observed up to day 30 for both the soils. The toxicological effect of ethion on microbiological and biochemical parameters persisted till their corresponding half-lives. The microbial metabolic quotient and microbial respiration quotient were altered, but was short-lived, indicating ethion induced disturbances. The recovery of the depressive action at 10FR ethion spiking on the studied variables was of slightly longer duration than noticed at FR application, although the depressive effect was overcoming after the respective half-lives of ethion. The microbial and biochemical soil parameters were negatively correlated with application of ethion up to day 60 of incubation.  相似文献   

17.
氯代持久性有机污染物的农田土壤污染呈现污染浓度低、面积大、新源污染不断输入的特点。农田土壤本身微生物种类丰富,对氯代有机污染物具有较大的降解潜力和未知性。本试验以典型高氯代和低氯代持久性有机污染物——六氯苯(HCB)和滴滴涕(DDT)为研究对象,结合~(14)C同位素示踪技术,研究HCB和DDT在热带水稻土和甘蔗地土壤的矿化现象,同时监测HCB和DDT在两种土壤中的挥发、降解产物以及结合残留。结果表明,经84 d好氧培养,HCB和DDT在两种土壤中的矿化量分别仅为0.14%和3%,低氯代有机污染物DDT的矿化速率显著高于高氯代有机污染物HCB。然而,两种土壤对HCB或DDT的矿化没有显著性差异。HCB或DDT在水稻土中的挥发量略微高于甘蔗地土壤,两种土壤中HCB和DDT的挥发量在0.1%~0.6%之间,表明挥发不是其主要的环境过程。在DDT污染水稻土和甘蔗地土壤中添加1.25%的堆肥增加了DDT在土壤中的矿化与结合残留,减少了DDT的挥发。本研究结果表明土壤在好氧条件下对氯代持久性有机污染物的自然消解能力非常弱,而有机肥的使用有助于土壤中持久性氯代有机污染物的矿化消除。  相似文献   

18.
Behaviour of Cyanides in Soil and Groundwater: A Review   总被引：1，自引：0，他引：1  
Most people associate the word cyanide with an extremely dangerous and fast-acting poison. However, there are several cyanide species, of varying toxicity, depending on the source to cyanide contamination. The most important cyanide compounds, as well as the most important sources of cyanide contamination in soils and groundwater are discussed. Toxicological and analytical aspects of cyanide containing compounds are briefly touched. The behaviour of cyanide compounds in soil and groundwater is governed by many interacting chemical and microbial processes. Redox conditions and pH are of importance for the leaching and degradation of iron cyanide complexes. Free cyanide is degraded under both aerobic and anaerobic conditions, while documentation of the degradability of iron cyanide complexes only exists under aerobic conditions. The risk associated to the cyanide contained in the different types of sources is evaluated. At gas work sites, where cyanide is mainly present as iron cyanide complexes, the risk for effects on humans from exposure to cyanide compounds seems to be of minor relevance.  相似文献   

19.
Volatilization of sulfur from unamended and sulfate-treated soils was studied by sensitive gas chromatographic techniques using a flame photometric detector fitted with a sulfur filter. The soils employed were surface samples of 25 Iowa soils selected to obtain a wide range in properties. No release of volatile sulfur compounds was detected when 11 of these soils were incubated under aerobic or waterlogged conditions before or after treatment with sulfate (400 μg sulfate S/g soil). Fourteen soils released volatile sulfur compounds when incubated under waterlogged conditions before and after addition of sulfate, but only 4 of these soils released volatile sulfur compounds when incubated under aerobic conditions. Where volatilization of sulfur was observed, the volatile sulfur detected was identified as dimethyl sulfide or as dimethyl sulfide associated with smaller amounts of carbonyl sulfide, carbon disulfide, methyl mercaptan, and (or) dimethyl disulfide. No trace of hydrogen sulfide was detected. Where release of volatile sulfur was observed, the amount of sulfur volatilized at 30°C in 60 days under aerobic or waterlogged conditions was very small and did not account for more than 0–05% of the sulfur in the unamended or sulfate-treated soils studied. It is concluded that gaseous loss of sulfur from unamended or sulfate-treated soils is insignificant under conditions likely to be encountered in the field.  相似文献   

20.
Summary Several workers have reported that O2 has little, if any, effect on hydrolysis of urea by soil urease, but others have reported that it has a marked effect, hydrolysis being significantly faster in soils under aerobic conditions than in O2-depleted soils. In studies to account for these divergent results, we found that whereas plant residues and other readily decomposable organic materials markedly stimulated microbial production of urease in soils under aerobic conditions, they did not greatly stimulate production of urease in soils under anaerobic conditions. We also found that although anaerobic conditions retarded production of urease by soil microorganisms, they did not inhibit hydrolysis of urea by soil urease. These observations suggest that the divergent findings concerning the effect of O2 on hydrolysis of urea by soil urease may have resulted from differences in the amounts of readily decomposable organic materials in the soils studied.  相似文献   

设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号