The environmental fate of phthalate esters: A literature review

In addition to the often-cited advantages of using Arabidopsis thaliana as a model system in plant biological research (1), Arabidopsis has many additional characteristics that make it an attractive experimental organism for studying lea d (Pb) accumulation and tolerance in plants. These include its fortuitous familial relationship to many known metal hyperaccumulators (Brassicaceae), as well as similar Pbaccumulation patterns to most other plants. Using nutrient-agar plates, hydroponic culture, and Pb-contaminated soils as growth media, we found significant variation in Arabidopsis thaliana ecotypes in accumulation and tolerance of Pb. In addition, we have found that Pb accumulation is not obligatorily linked with Pb tolerance, suggesti ng that different genetic factors control these two processes. We also screened ethyl methanesulfonate-mutagenized M2 populations and identified several Pb-accumulating mutants. Current characterization of these mutants indicates that their phenotypes are likely due to alteration of general metal ion uptake or translocation processes since these mutants also accumulate many other metals in shoots. We expect that further characterization of the ecotypes and mutants will shed light on the basic genetic and physiological underpinnings of plant-based Pb remediation. 7. Aromatic nitroreduction of acifluorfen in soils, rhizospheres, and pure cultures of rhizobacteria. Zablotowicz, R. M., Locke, M. A., and Hoagland, R. E. Phytoremediation of soil and water contaminants. Washington, DC : American Chemical Society, 1997. p. 38-53. NAL Call #: QD1.A45-no.664 Abstract: Reduction of nitroaromatic compounds to their corresponding amino derivatives is one of several pathways in the degradation of nitroxenobiotics. Our studies with the nitrodiphenyl ether herbicide acifluorfen showed rapid metabolism to am inoacifluorfen followed by incorporation into unextractable soil components in both soil and rhizosphere suspensions. Aminoacifluorfen was formed more rapidly in rhizospheres compared to soil, which can be attributed to higher microbial populations, espec ially of Gram-negative bacteria. We identified several strains of Pseudomonas fluorescens that possess nitroreductase activity capable of converting acifluorfen to aminoacifluorfen. Factors affecting acifluorfen nitroreductase activity in pure cultures an d cell-free extracts, and other catabolic transformations of acifluorfen, ether bond cleavage, are discussed. Plant rhizospheres should be conducive for aromatic nitroreduction. Nitroreduction by rhizobacteria is an important catabolic pathway for the ini tial degradation of various nitroherbicides and other nitroaromatic compounds in soils under Reduction of nitroaromatic compounds to their corresponding amino derivatives is one of several pathways in the degradation of nitroxenobiotics. Our studies with the nitrodiphenyl ether herbicide acifluorfen showed rapid metabolism to am inoacifluorfen followed by incorporation into unextractable soil components in both soil and rhizosphere suspensions. Aminoacifluorfen was formed more rapidly in rhizospheres compared to soil, which can be attributed to higher microbial populations, espec ially of Gram-negative bacteria. We identified several strains of Pseudomonas fluorescens that possess nitroreductase activity capable of converting acifluorfen to aminoacifluorfen. Factors affecting acifluorfen nitroreductase activity in pure cultures an d cell-free extracts, and other catabolic transformations of acifluorfen, ether bond cleavage, are discussed. Plant rhizospheres should be conducive for aromatic nitroreduction. Nitroreduction by rhizobacteria is an important catabolic pathway for the ini tial degradation of various nitroherbicides and other nitroaromatic compounds in soils under phytoremediation management. 8. Ascorbate: a biomarker of herbicide stress in wetland plants. Lytle, T. F. and Lytle, J. S. Phytoremediation of soil and water contaminants. Washington, DC : American Chemical Society, 1997. p. 106-113. NAL Call #: QD1.A45-no.664 Abstract: In laboratory exposures of wetland plants to low herbicide levels (<0.1 micrograms/mL), some plants showed increased total ascorbic acid suggesting a stimulatory effect on ascorbic acid synthesis occurred; at higher herbicide conce ntrations (greater than or equal to 0.1 micrograms/mL) a notable decline in total ascorbic acid and increase in the oxidized form, dehydroascorbic acid occurred. Vigna luteola and Sesbania vesicaria were exposed for 7 and 21 days respectively to atrazine (0.05 to 1 microgram/mL); Spartina alterniflora 28 days at 0.1 micrograms/mL trifluralin; Hibiscus moscheutos 14 days at 0.1 and 1 microgram/mL metolachlor in fresh and brackish water. The greatest increase following low dosage occurred with S. alterniflo ra, increasing from <600 micrograms/g wet wt. total ascorbic acid to >1000 micrograms/g. Ascorbic acid may be a promising biomarker of estuarine plants exposed to herbicide runoff; stimulation of ascorbic acid synthesis may enable some wetland plant s used in phytoremediation to cope with low levels of these compounds. In laboratory exposures of wetland plants to low herbicide levels (<0.1 micrograms/mL), some plants showed increased total ascorbic acid suggesting a stimulatory effect on ascorbic acid synthesis occurred; at higher herbicide conce ntrations (greater than or equal to 0.1 micrograms/mL) a notable decline in total ascorbic acid and increase in the oxidized form, dehydroascorbic acid occurred. Vigna luteola and Sesbania vesicaria were exposed for 7 and 21 days respectively to atrazine (0.05 to 1 microgram/mL); Spartina alterniflora 28 days at 0.1 micrograms/mL trifluralin; Hibiscus moscheutos 14 days at 0.1 and 1 microgram/mL metolachlor in fresh and brackish water. The greatest increase following low dosage occurred with S. alterniflo ra, increasing from <600 micrograms/g wet wt. total ascorbic acid to >1000 micrograms/g. Ascorbic acid may be a promising biomarker of estuarine plants exposed to herbicide runoff; stimulation of ascorbic acid synthesis may enable some wetland plant s used in phytoremediation to cope with low levels of these compounds. 9. Atmospheric nitrogenous compounds and ozone--is NO(x) fixation by plants a possible solution. Wellburn, A. R. New phytol. 139: 1 pp. 5-9. (May 1998). NAL Call #: 450-N42 Descriptors: ozoneair-pollution nitrogen-dioxide nitric-oxide air-quality tolerancebioremediationacclimatizationnutrient-sources nutrient-uptake plantscultivarsgenetic-variation literature-reviews 10. Atrazine degradation in pesticide-contaminated soils: phytoremediation potential. Kruger, E. L., Anhalt, J. C., Sorenson, D., Nelson, B., Chouhy, A. L., Anderson, T. A., and Coats, J. R. Phytoremediation of soil and water contaminants. Washington, DC : American Chemical Society, 1997. p. 54-64. NAL Call #: QD1.A45-no. 664 Abstract: Studies were conducted in the laboratory to determine the fate of atrazine in pesticide-contaminated soils from agrochemical dealer sites. No significant differences in atrazine concentrations occurred in soils treated with atrazine i ndividually or combinations with metolachlor and trifluralin. In a screening study carried out in soils from four agrochemical dealer sites, rapid mineralization of atrazine occurred in three out of eight soils tested, with the greatest amount occurring i n Bravo rhizosphere soil (35% of the applied atrazine after 9 weeks). Suppression of atrazine mineralization in the Bravo rhizosphere soil did not occur with the addition of high concentrations of herbicide mixtures, but instead was increased. Plants had a positive impact on dissipation of aged Studies were conducted in the laboratory to determine the fate of atrazine in pesticide-contaminated soils from agrochemical dealer sites. No significant differences in atrazine concentrations occurred in soils treated with atrazine i ndividually or combinations with metolachlor and trifluralin. In a screening study carried out in soils from four agrochemical dealer sites, rapid mineralization of atrazine occurred in three out of eight soils tested, with the greatest amount occurring i n Bravo rhizosphere soil (35% of the applied atrazine after 9 weeks). Suppression of atrazine mineralization in the Bravo rhizosphere soil did not occur with the addition of high concentrations of herbicide mixtures, but instead was increased. Plants had a positive impact on dissipation of aged atrazine in soil, with significantly less atrazine extractable from Kochia-vegetated soils than from nonvegetated soils. 11. Bacterial inoculants of forage grasses that enhance degradation of 2-chlorobenzoic acid in soil. Siciliano, S. D. and Germida, J. J. Environ toxicol chem. 16: 6 pp. 1098-1104. (June 1997). NAL Call #: QH545.A1E58 Descriptors: polluted-soils bioremediationAbstract: Biological remediation of contaminated soil is an effective method of reducing risk to human and ecosystem health. Bacteria and plants might be used to enhance remediation of soil pollutants in situ. This study assessed the potential of bacteria (12 isolates), plants (16 forage grasses), and plant-bacteria associations (selected pairings) to remediate 2-chlorobenzoic acid (2CBA)-contaminated soil. Initially, grass viability was assessed in 2CBA-contaminated soil. Soil was contaminated wi th 2CBA, forage grasses were grown under growth chamber conditions for 42 or 60 d, and the 2CBA concentration in soil was determined by gas chromatography. Only five of 16 forage grasses grew in 2CBA-treated (816 mg/kg) soil. Growth of Bromus inermis had no effect on 2CBA concentration, whereas Agropyron intermedium, B. biebersteinii, A. riparum, and Elymus dauricus decreased 2CBA relative to nonplanted control soil by 32 to 42%. The 12 bacteria isolates were screened for their ability to promote the germ ination of the five grasses in 2CBA-contaminated soil. Inoculation of A. riparum with Pseudomonas aeruginos

Phytoremediation : 植物による環境/土壌浄化

The hypothesis that ‘microplastic will transfer hazardous hydrophobic organic chemicals (HOC) to marine animals’ has been central to the perceived hazard and risk of plastic in the marine environment. The hypothesis is often cited and has gained momentum, turning it into paradigm status. We provide a critical evaluation of the scientific literature regarding this hypothesis. Using new calculations based on published studies, we explain the sometimes contrasting views and unify them in one interpretive framework. One explanation for the contrasting views among studies is that they test different hypotheses. When reframed in the context of the above hypothesis, the available data become consistent. We show that HOC microplastic-water partitioning can be assumed to be at equilibrium for most microplastic residing in the oceans. We calculate the fraction of total HOC sorbed by plastics to be small compared to that sorbed by other media in the ocean. We further demonstrate consistency among (a) measured HOC tr...

Microplastic as a Vector for Chemicals in the Aquatic Environment: Critical Review and Model-Supported Reinterpretation of Empirical Studies

An understanding of sorption processes is an important key to describing pollutant fate in an aquatic system because sorption may alter significantly physical transport and chemical reactivity of pollutants. The sorption of uncharged organic chemicals to natural aquatic sorbents is dominated by “hydrophobic interactions.” For composite particulates (i.e., sediments/soils), organic matter is the primary sorbing constituent. Sorption partition coefficients, indexed to organic carbon (Koc), are relatively invariant for natural sorbents. Koc's can be estimated from other physical properties of pollutants (aqueous solubility or octanol/water partition coefficients). Hydrophilic contributions to sorption tend to occur with one or both of the following conditions: (1) High sorbate polarity; and (2) low organic carbon content of the sorbent, especially with coincident high clay content. Although a priori estimation techniques comparable to hydrophobic sorption are not presently available, hydrophilic contribution...

Organic Pollutant Sorption in Aquatic Systems

DISCLAIMER The use of company or product name(s) is for identification only and does not imply endorsement by the Agency for Toxic Substances and Disease Registry. A toxicological Profile for PCBs, Draft for Public Comment, was released in December 1998. This edition supercedes any previously released draft or final profile. Toxicological profiles are revised and republished as necessary, but no less than once every three years. The toxicological profiles are developed in response to the Superfund Amendments and Reauthorization Act (SARA) of 1986 (Public law 99-499) which amended the Comprehensive Environmental Response, Compensation, and Liability Act of 1980 (CERCLA or Superfund). This public law directed ATSDR to prepared toxicological profiles for hazardous substances most commonly found at facilities on the CERCLA National Priorities List and that pose the most significant potential threat to human health, as determined by ATSDR and the EPA. The availability of the revised priority list of 275 hazardous substances was announced in the Administrator of ATSDR to prepare a toxicological profile for each substance on the list. Toxicological Profiles are a unique compilation of toxicological information on a given hazardous substance. Each profile reflects a comprehensive and extensive evaluation, summary, and interpretation of available toxicologic and epidemiologic information on a substance. Health care providers treating patients potentially exposed to hazardous substances will find the following information helpful for fast answers to often-asked questions. Chapter 1: Public Health Statement: The Public Health Statement can be a useful tool for educating patients about possible exposure to a hazardous substance. It explains a substance's relevant toxicologic properties in a nontechnical, question-and-answer format, and it includes a review of the general health effects observed following exposure. Chapter 3: Health Effects: Specific health effects of a given hazardous compound are reported by type of health effect (death, systemic, immunologic, reproductive), by route of exposure, and by length of exposure (acute, intermediate, and chronic). In addition, both human and animal studies are reported in this section. NOTE: Not all health effects reported in this section are necessarily observed in the clinical setting. Please refer to the Public Health Statement to identify general health effects observed following exposure. The following additional material can be ordered through the ATSDR Information Center: Case Studies in Environmental Medicine: Taking an Exposure History—The importance of taking an exposure history and how to conduct one are described, and an example of a thorough exposure history is provided. Other …

Toxicological profile for polychlorinated biphenyls (PCBs)

Calculating pesticide sorption coefficients (Kd) using selected soil properties.

Many new organic agricultural chemicals have been developed which offer great potential in the production and preservation of food and fiber (Weber 1969). In the process of developing and utilizing these chemicals we must come to understand how they affect the target organisms and what becomes of them after they have done their job. The purpose of this review is to discuss1 the behavior of one family of these organic compounds, the s-triazines, at the molecular level, in systems in which the chemicals are associated with clay minerals. Factors affecting the adsorption and release of s-triazines by clay colloids and the availability of the compounds to plant roots will also be included. The literature citations are limited to those studies in which s-triazines and clays were directly associated and situations in which other compounds behaved in a manner similar to the s-triazines.

Mechanisms of adsorption of s-triazines by clay colloids and factors affecting plant availability.

The adsorption of seven s-triazines from aqueous solutions by organic soil colloids was determined at pH levels from 1.0 to 5.2. Maximum adsorption occurred at pH levels in the vicinity of the pKA values of the respective compounds. The amounts adsorbed were dependent upon the molecular structures of the compounds and the pH of the suspension and were, in order of decreasing adsorption, as follows: 2-methoxy-4,6-bis(diethylamino)-s-triazine (hereafter referred to as tetraetatone) = 2,4-bis(isopropylamino)-6-methylmercapto-s-triazine (prometryne) = 2-hydroxy-4,6-bis(isopropylamino)-s-triazine (hereafter referred to as hydroxypropazine) > 2-methoxy-4-diethylamino-6-ethylamino-s-triazine (hereafter referred to as trietatone) > 2-methoxy-4,6-bis(isopropylamino)-s-triazine (prometone) > 2-methoxy-4,6-bis(ethylamino-s-triazine (simetone) > 2-chloro-4,6-bis(isopropylamino-s-triazine (propazine). Approximately 52% of the prometone adsorbed by the organic matter was desorbed with two extractions of 0.1N NaCl. It was concluded that the adsorption of the s-triazines was due to complexing of the triazine molecules with functional groups on the organic colloids and/or adsorption of s-triazine cations by ion exchange forces.

Adsorption of s-Triazines by Soil Organic Matter

Alachlor [2-chloro-N-(2,6-diethylphenyl)-N-(methoxymethyl)acetamide] and metolachlor [2-chloro-N-(2-ethyl-6-methylphenyl)-N-(2-methoxy-1-methylethyl)acetamide] adsorption was positively correlated with soil organic-matter content, clay content, and surface area as measured by ethylene glycol monoethyl ether (EGME) or benzyl ethyl ether (BEE) and inversely correlated with herbicidal activity. Alachlor was adsorbed in slightly greater amounts by soil than metolachlor. Metolachlor had slightly greater bioactivity than alachlor on grass weeds, but the herbicides had similar activity on broadleaf weeds. Slightly greater amounts of metolachlor than alachlor were leached through a Norfolk soil and slightly greater amounts of alachlor were retained in the upper soil zones, compared with metolachlor.

Jerome B. Weber

Papers

Calculating pesticide sorption coefficients (Kd) using selected soil properties.

Mechanisms of adsorption of s-triazines by clay colloids and factors affecting plant availability.

Adsorption of s-Triazines by Soil Organic Matter

Adsorption, mobility, and efficacy of alachlor and metolachlor as influenced by soil properties.

Adsorption-desorption of selected pesticides by organic matter and montmorillonite.