Grantee Research Project Results
Final Report: Tracking Persistent Organic Pollutants (POPs) Through Biotic and Abiotic Processes in the Environment
EPA Grant Number: R828174Title: Tracking Persistent Organic Pollutants (POPs) Through Biotic and Abiotic Processes in the Environment
Investigators: Mattina, MaryJane Incorvia , Eitzer, Brian , Simon, Ted
Institution: Connecticut Agricultural Experiment Station
EPA Project Officer: Hahn, Intaek
Project Period: July 1, 2000 through June 30, 2002
Project Amount: $194,622
RFA: Exploratory Research - Engineering, Chemistry, and Physics) (1999) RFA Text | Recipients Lists
Research Category: Water , Land and Waste Management , Air , Safer Chemicals
Objective:
Over time, organic soil contaminants bind to soil particles and resist extraction, microbial degradation, and volatilization. This phenomenon results in the formation of weathered residues, the behavior of which is markedly different from that of freshly applied residues. The objective of this research project was to examine the cycling of weathered soil residues between the soil, air, and plant compartments by testing the following five hypotheses: (1) Volatilization flux of weathered persistent organic pollutants (POPs) from soil makes a small but measurable contribution to atmospheric levels of POPs (soil-to-air translocation). (2) Very low soil concentrations of POPs reflect atmospheric deposition to the site more than they reflect direct application of an agrochemical (air-to-soil translocation). (3) POPs dose/uptake curves for soil-to-root and air-to-leaf pathways can be established (soil-to-root and air-to-leaf translocation). (4) Transpiration flux of POPs from plants makes a small but measurable contribution to atmospheric concentrations (leaf-to-air translocation). (5) Municipal and commercial compost sources, as well as commercial topsoil and potting soil, contain significant amounts of POPs available for anthropogenic translocation. The cycling of weathered POPs through the biosphere must be clarified before the full impact of POPs on human health can be assessed comprehensively.
Summary/Accomplishments (Outputs/Outcomes):
Development of New Analytical Procedures
The analytical methods developed in our laboratories to accomplish the grant objectives evolved during the course of the investigations. Numerous standard operating procedures have been written, based largely on chiral gas chromatography (GC) with ion trap mass spectrometry (MS) and were adhered to for all determinations. Salient features of the analytical techniques developed as part of this project as listed below. Further information can be found in Eitzer, et al. (2001) and Mattina, et al. (2004).
Internal Standards. The analysis of all samples—polyurethane from plugs (PUFs) from air analyses, soil, plant compartments, and compost—is initiated with the spiking of internal standards (IS) into the matrix at the start of extraction and cleanup. Initially, 13C10 trans-chlordane and 13C10 trans-nonachlor were spiked for the analysis of the chlordane residues; we have recently included 13C12-p,p’-DDE and numerous D8 to 12-PAHs as IS for the analogous native analytes. All quantitations are performed by the IS calibration method. This method compensates for the loss of native analyte through the extraction and cleanup steps, providing an accurate value of the native components initially present in the sample.
Gas Chromatography/Ion Trap Mass Spectrometry. A robust analytical method based on chiral GC with MS detection was developed and updated, as required, throughout the investigations. For resolution of enantiomers of trans-chlordane (TC), cis-chlordane (CC), MC5, and exo-heptachlorepoxide (HEPX), we use a 30 m x 0.25 mm I.D., 0.25 µm Df γ–DEX chiral column. The enantiomers of oxychlordane (OXY), heptachlor (HEPT), and endo-heptachlorepoxide are not resolved on this column. We examined a bonded chiral GC column, the Chirasil-DEX CB bonded column from Varian. It was hoped that the bonded nature of this column would reduce column bleed and background noise and increase column lifetimes. The resolution of the OXY, TC, and CC enantiomers was exceptionally good on this column, but unfortunately this column could not achieve baseline resolution of –CC and +TC. Therefore, we continued analyses on the nonbonded γ–DEX chiral column from Supelco.
The chiral GC columns were fouled rapidly by consecutive injections of compost samples. To prolong chiral GC column lifetimes, a 0.5 m guard column (uncoated fused silica capillary tubing) was inserted at the head of the chiral column. Because the chiral GC columns are non-bonded, column bleed into the ion trap tends to elevate background noise levels. To reduce background noise levels, a 0.5 m length of uncoated fused silica capillary tubing is inserted in the interface between the end of the chiral GC column and the MS source. The interface temperature then can be raised without thermally dislodging chiral phase into the source. To prolong chiral GC column lifetimes, we also have found it necessary to inject iso-octane between all injections of compost samples, a procedure that was not required for other matrices.
Analysis for Oxychlordane. This GC/ion trap detection (ITD) analysis used a 15 m x 0.25 mm I.D. x 0.25 Df Cyclosil B chiral column (J&W Scientific) to separate OXY enantiomers. Temperature and ramp programs were developed, which are specific for this analysis.
Raw Data Enhancement With PeakFit and Data Acceptance Criteria. Raw ITD data files are smoothed and integrated using PeakFit software. This permits the detection level to be considerably lowered below levels possible using the ion trap manufacturer’s software. For each component, two ions within an isotope cluster are monitored and processed. The isotope ratio is assessed from two sets of authentic standards injected along with a sample set. The isotope ratios for the samples injected must be within two standard deviations of the isotope ratios from the corresponding standard sets for the sample data to be acceptable.
Extraction and Cleanup Methods for a Variety of Matrices.
- Soil: A homogenous soil sample is placed in the microwave-assisted extraction (MAE) vessel, spiked with IS, and extracted with 2:3 hexane:acetone. The extraction solution is solvent exchanged to iso-octane prior to injection into the GC/ITD.
- Compost: Compost samples are thoroughly mixed. Twigs and pebbles are removed and two 10-gram subsamples then are collected for extraction. After transfer of a subsample to the blender jar, the extraction and cleanup procedures for plant tissue are used as described in the following section.
- Plant compartments (plant tissue): Plant tissue is thoroughly rinsed of soil, chopped, placed in a blender jar, spiked with IS, and extracted with 1:2 isopropanol:petroleum ether. The petroleum ether layer is cleaned up over Florisil and solvent exchanged to iso-octane. The iso-octane extract is injected into the GC/ITD.
- Plant compartments (xylem sap): Xylem sap is collected from the severed stems of container-grown plants, noting volume of sap and time-for-collection. The stem exudate is transferred to a conical vial and spiked with IS. Using a procedure developed in our laboratory (Mattina, et al., 2004), organic analytes are extracted from the aqueous sap using solid phase micro-extraction fibers (SPME; see Figure 1). Desorption of the fiber in the GC inlet is followed by chiral GC/ITD analysis.
- Air: High volume air samplers are equipped with glass fiber filters (GFFs) to collect particulates and PUFs to collect vapor phase compounds. The PUFs are spiked with IS and Soxhlet-extracted with petroleum ether. The extraction solution is cleaned up over Florisil, solvent exchanged to iso-octane, and analyzed by chiral GC/ITD. The GFFs are extracted with the MAE procedure described for soils. The extract is then solvent exchanged to petroleum ether and then cleaned up on a Florisil column.
Figure 1. Extraction of Organic Analytes From Xylem Sap Using Solid Phase Microextraction Fibers
POPs Translocation
Anthropogenic Translocation. Most previous investigations of POPs have focused on nonpoint sources as contributors to POPs cycling through the environment, for example, soil-to-air and water-to-air pathways. In contrast to these previous studies, one aspect of the current project is the investigation of a point source, compost, and its anthropogenic translocation as contributors to POPs cycling through the environment.
Thirteen commercial compost samples (comm) were purchased, and 39 samples of municipal composts (muni) were collected from facilities across the state. The total chlordane concentration (expressed as TC+CC+TN on a dry weight basis) for six compositional categories of compost is shown in Figure 2. From extensive analysis of the data associated with the compost samples, we justify the conclusion that soil as a compost feedstock is not the sole contribution to the chlordane concentration in the final product; leaves, on the other hand, do appear to be a major source of chlordane. A manuscript on this compost study with detailed information regarding component and chiral chlordane fractions was published (Lee, et al., 2003).
Figure 2. Distribution of Chlordane in Compost Samples. Legend: C, containing organic and manure compost; TS (comm), containing topsoil and/or sand; C + TS, containing a mixture of compost and topsoil; L, leaf and/or wood chip compost; TS (muni), primarily topsoil; L + TS, a mixture of leaf compost and topsoil-sand.
Our investigations into the anthropogenic translocation of POPs through the biosphere has drawn international attention. We collaborated with a laboratory in Tunisia to determine POPs concentration in compost samples. Accordingly, we arranged the appropriate permits through the U.S. Department of Agriculture to receive four compost samples from Tunisia. These samples were analyzed. Only one of the four samples, designated as consisting solely of municipal solid waste, was found to contain POPs, namely 4.3 ppb p,p’-DDE and 21.8 ppb DDT.
Soil-to-Air Pathway. Collection of atmospheric samples for determination of chlordane concentration was extensive throughout the grant period. From June 2000 through September 2002, ambient air samples were collected periodically at three heights (0.5 m, 1.5 m, and 2.5 m) above the experimental plot on the Connecticut Agriculture Experiment Station (CAES) campus. This plot is well characterized with regard to chlordane treatment and subsequent history.
In addition, air samples were collected throughout this period at a single height at a background site, approximately 25 meters from the treated plot on the CAES campus. From May 2001 through September 2002, a suburban site, Lockwood Farm in Hamden, CT, the experimental farm belonging to CAES, was monitored. Two additional background sites were monitored from March to September 2002; the first, an urban site in downtown Waterbury, CT, and the second, a rural site at a fish hatchery in Burlington, CT.
The data we have collected represent the first long-term study of ambient air above a contaminated soil. The duration of the study allows additional insight into the volatilization process previously unavailable. The data permit comparison with chlordane concentrations in ambient air at alternate sites. A small portion of the data is summarized in Figures 3 and 4. The complete study has been published (Eitzer, et al., 2003).
Figure 3. Average Ambient Air Profiles at Each Height Above the Plot (Each Component as a Fraction of the Total) and Total Concentration From March-September 2002 Along With Average Soil Profile and Concentration
Figure 4. Average Ambient Air Profiles (Each Component as a Fraction of the Total) and Total Concentration From March-September 2002 For Each of the Four Ambient Background Sites
Soil-to-Root Pathway and Translocation Within Plant Tissues. Several food crops were grown in the field and the chlordane component concentrations were measured in the soil contiguous to these crops, as well as in various plant tissues. The concentration of each chlordane component in the roots normalized to its value in the soil for these crops is shown in Figure 5 (Mattina, et al., 2002). It is apparent that different crops accumulate chlordane components differently. The unique status of Cucurbita pepo L. (zucchini) also is evident in this figure. Data not shown indicate that enantiomers translocate differently through plant tissue (Mattina, et al., 2002; Mattina, et al., 2004).
Figure 5. Chlordane Component Concentration in Roots Normalized to Concentration in Soil
Soil-to-Plant Dose/Uptake Study. C. pepo L. was grown in soil containing four different concentrations of chlordane in bins that were positioned in the field without contacting the field soil. The chlordane component concentrations were determined in the soil before and after planting, and in the individual C. pepo L.tissues of roots, stems, leaves, and fruit at destructive harvest. The log-transformed data are shown in Figure 6, along with data from the direct field sowing of C. pepo L. in 2000. It is interesting to note that the relationship between the tissue and the soil concentration for roots, stems, and leaves is similar, and notably different from that for fruit. This observation may reflect the plant’s physiology, suggesting that the dominant uptake route may vary for a given tissue type within the same plant. These data are in press (Mattina, et al., 2004).
Figure 6. Dose/Uptake Study for C. Pepo
We also examined another plant species, Lupinus albus (lupin), with respect to root exudates. Such exudates may play a significant role in elucidating the soil-to-plant uptake mechanisms.
Air-to-Plant Pathway and Translocation Within Plant Tissues. Experiments were completed to examine an alternate plant uptake route for C. pepo L. Zucchini plants were grown in clean soil in bins in two separate greenhouses containing significantly different chlordane ambient air concentrations. The experimental setup is shown in Figure 7. One of the most surprising results of these trials is the confirmation of translocation of the chlordane taken up through the leaves, through the phloem, and throughout plant tissues including accumulation in the roots. This study has been published (Lee, et al., 2003).
Figure 7. Greenhouse Trial for Investigation of Dose of Chlordane in Air/Uptake By C. Pepo
Broad Impacts of the Research
The data from this project impact long-term environmental issues related to POPs in several significant ways:
- Robust methods for quantitation of chiral pollutants in a variety of environmental compartments were generated.
- Compost, a matrix generally regarded as environmentally beneficial, was shown to contribute to the cycling of POPs through the biosphere.
- Highly weathered POP residues in soil were shown to volatilize from the soil compartment to the contiguous air. This demonstrates that POP residues in soil ought not to be considered “irreversibly” bound within the soil matrix.
- C. pepo L. (zucchini) is exceptional among terrestrial plants in its ability to uptake and translocate a structurally diverse range of highly hydrophobic POP residues sequestered in the soil matrix, again demonstrating that POP residues in soil ought not to be considered “irreversibly” bound within the soil matrix.
- Terrestrial plants as represented by C. pepo L. may be contaminated by two uptake pathways—a soil-to-plant pathway and an air-to-plant pathway. Thus, agricultural plants will contribute to the dietary burden of POPs for the foreseeable future.
- The chiral handle associated with some POPs may be exploited to distinguish between the soil-to-plant pathway and air-to-plant pathways. One such data presentation is shown in Figures 8 and 9.
- As a result of the studies made possible by this grant, we have begun to investigate the uptake mechanisms underlying these observations. Our laboratory has received a grant for these phytoremediation studies (EPA Grant No. R829405, Mechanistic Role of Plant Root Exudates in the Phytoremediation of Persistent Organic Pollutants) . Our work has been acknowledged by invitations to present at conferences such as the 4th Society of Environmental Toxicology and Chemistry World Congress in Portland, OR, in November 2004.
Figure 8. Changes in Chlordane Residue Profiles for the Air-to-Plant Uptake Route
Figure 9. Changes in Chlordane Residue Profiles for the Soil-to-Plant Uptake Route
Journal Articles on this Report : 7 Displayed | Download in RIS Format
Other project views: | All 17 publications | 7 publications in selected types | All 7 journal articles |
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Type | Citation | ||
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Eitzer BD, Mattina MI, Iannucci-Berger W. Compositional and chiral profiles of weathered chlordane residues in soil. Environmental Toxicology and Chemistry 2001;20(10):2198-2204. |
R828174 (2000) R828174 (2002) R828174 (Final) |
Exit |
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Eitzer BD, Iannucci-Berger W, Mattina MI. Volatilization of weathered chiral and achiral chlordane residues from soil. Environmental Science & Technology 2003;37(21):4887-4893. |
R828174 (Final) |
not available |
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Lee WY, Iannucci-Berger W, Eitzer BD, White JC, Mattina MI. Persistent organic pollutants in the environment: chlordane residues in compost. Journal of Environmental Quality 2003;32(1):224-231. |
R828174 (2002) R828174 (Final) |
Exit |
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Lee WY, Iannucci-Berger W, Eitzer BD, White JC, Mattina WI. Plant uptake and translocation of air-borne chlordane and comparison with the soil-to-plant route. Chemosphere 2003;53(2):111-121. |
R828174 (2002) R828174 (Final) R829405 (Final) |
Exit Exit Exit |
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Mattina MI, White J, Eitzer B, Iannucci-Berger W. Cycling of weathered chlordane residues in the environment: compositional and chiral profiles in contiguous soil, vegetation, and air compartments. Environmental Toxicology and Chemistry 2002;21(2):281-288. |
R828174 (2000) R828174 (2002) R828174 (Final) |
Exit |
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Mattina MI, Eitzer BD, Iannucci-Berger W, Lee WY, White JC. Plant uptake and translocation of highly weathered, soil-bound technical chlordane residues: Data from field and rhizotron studies. Environmental Toxicology and Chemistry 2004;23(11):2756-2762. |
R828174 (Final) R829405 (Final) |
not available |
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White JC, Mattina MJI, Eitzer BD, Iannucci-Berger W. Tracking chlordane compositional and chiral profiles in soil and vegetation. Chemosphere 2002;47(6):639-646. |
R828174 (2002) R828174 (Final) |
Exit Exit Exit |
Supplemental Keywords:
atmosphere, soil, chemical transport, health effects, dose-response, measurement methods, environmental chemistry, air toxics, chemical mixtures, climate change, genetic susceptibility, pesticides, tropospheric ozone, chlordane, DDT, abiotic processes, agrichemicals, agricultural community, agriculture, atmospheric deposition, atmospheric processes, biodegradation, biotic processes, chemical contaminants, climate variations, contaminant transport, contaminated sediment, degradation of organic pollutants, dietary exposure, environmental hazard exposures, exposure, exposure and effects, exposure assessment, fate and transport, human exposure, insecticides, mass spectrometry, MS, microbial degradation, organic soil contaminants, persistent organic pollutants, POPs, pesticide residues, pesticide runoff, pollutants, sediment transport, sensitive populations, soil contaminants, stratospheric ozone,, RFA, Scientific Discipline, Health, Air, Toxics, Waste, Water, Ecosystem Protection/Environmental Exposure & Risk, Bioavailability, air toxics, Environmental Chemistry, Contaminated Sediments, pesticides, Fate & Transport, chemical mixtures, Susceptibility/Sensitive Population/Genetic Susceptibility, Environmental Monitoring, tropospheric ozone, genetic susceptability, Engineering, Chemistry, & Physics, fate and transport, health effects, sensitive populations, atmospheric processes, degradation of organic pollutants, exposure and effects, mass spectrometry, stratospheric ozone, biotic processes, microbial degradation, contaminant transport, contaminated sediment, exposure, climate variations, biodegradation, sediment transport, Chlordane, chemical contaminants, chemical transport, human exposure, insecticides, abiotic processes, soil contaminants, DDT, organic soil contaminants, pesticide residues, pollutants, agriculture, weathering, Chlordane (technical mixture and metabolites), pesticide runoff, agrichemicals, dietary exposure, persistent organic pollutants, atmospheric deposition, agricultural community, exposure assessment, persistant organic pollutantsProgress and Final Reports:
Original AbstractThe perspectives, information and conclusions conveyed in research project abstracts, progress reports, final reports, journal abstracts and journal publications convey the viewpoints of the principal investigator and may not represent the views and policies of ORD and EPA. Conclusions drawn by the principal investigators have not been reviewed by the Agency.