Grantee Research Project Results
2000 Progress 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 Period Covered by this Report: July 1, 2000 through June 30, 2001
Project Amount: $194,622
RFA: Exploratory Research - Engineering, Chemistry, and Physics) (1999) RFA Text | Recipients Lists
Research Category: Water , Air , Safer Chemicals , Land and Waste Management
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. This proposal will 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 POPs from soil makes a small, but measurable, contribution to atmospheric levels of persistent organic pollutants (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); and (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.
Progress Summary:
The analytical methodologies developed in our laboratories to accomplish the grant objectives will continue to evolve during the course of these investigations. Several different standard operating procedures (SOPs) have been written, based on chiral gas chromatography with ion trap mass spectrometry, and are adhered to for all determinations. Salient features of the analytical techniques developed as part of this project include:
· Internal standards. The analysis of all samples-PUFs from air analysis, vegetation, soil, and compost-is initiated with the spiking of two internal standards (13C10 trans-chlordane and 13C10 trans-nonachlor) into the matrix at the start of extraction and cleanup. All quantitations are then performed by the internal standard calibration method. This method compensates for the loss of native analyte through the extraction and cleanup steps, providing an accurate value of the native chlordane components initially present in the sample.
· Gas chromatography/ion trap mass spectrometry. 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 -DEX
chiral column. The enantiomers of oxychlordane (OXY), heptachlor (HEPT), and
endo-heptachlorepoxide are not resolved on this column. The chiral GC
columns are rapidly fouled by consecutive injections of compost samples. To
prolong chiral GC column lifetimes, a 0.5 m guard column (uncoated fused silica
capillary tubing) has been 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
can then 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.
· Analysis for oxychlordane. This GC/ITD analysis uses a 15 m x 0.25 mm I.D. x 0.25 Df Cyclosil B chiral column to separate OXY enantiomers. Temperature and ramp programs have been developed that 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 from the ion trap manufacturer's software. For each chlordane 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 variety of matrices
1. Soil: A homogenous soil sample is placed in the microwave-assisted extraction (MAE) vessel, spiked with internal standards, and extracted with 2:3 hexane:acetone. The extraction solution is solvent exchanged to iso-octane prior to injection into the GC/ITD.
2. Compost: Compost samples are thoroughly mixed. Twigs and pebbles are removed, and two 10-gram subsamples are then collected for extraction. After transfer of a subsample to the blender jar, the extraction and cleanup procedures for vegetation are used as described in the following section.
3. Vegetation: Plant tissue is thoroughly rinsed of soil, chopped, placed in a blender jar, spiked with internal standards, and extracted with 1:2 iso-propanol/petroleum ether. Petroleum ether layer is cleaned up over Florisil and solvent exchanged to iso-octane. The iso-octane extract is injected into the GC/ITD.
4. Air: High-volume air samplers are equipped with glass fiber filters (GFFs) to collect particulates, and polyurethane foam plugs (PUFs) to collect vapor phase compounds. The PUFs are spiked with internal standards 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.
Assessment of Anthropogenic Translocation
Most previous investigations of POPs have focused on non-point sources as contributors to POPs cycling through the environment, for example, soil-to-air and water-to-air routes. 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 a contributor to POPs cycling through the environment. Thirteen commercial compost samples were purchased, and thirty-nine samples of municipal composts 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 1. From this histogram, we make the surprising observation that soil as a compost feedstock does not appear to make a major 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 is now in preparation.
Soil-to-Air Flux
During 2000, a total of 66 air samples were collected at 2-, 4-, and 8-foot heights above a well-defined, chlordane-contaminated soil, and at 4 feet above a site 100 feet from the contaminated site. The highest chlordane concentrations in the air were from samples collected at the lowest position (2 feet) above the contaminated soil. The chlordane concentration in the air collected at the 8-foot height was similar to that in air samples collected 100 feet from the chlordane-contaminated soil. Enantiomer fractions (EF) of TC and CC in air samples collected 2 feet above the contaminated soil were similar to the EFs in the soil itself. The EFs in the air at the 8-foot height were similar to the EFs in the air samples collected at the distant site. From these data, we conclude that volatilization from the contaminated soil is taking place. In 2001, we have been determining the rate of volatilization using two high-volume air samplers, temperature and wind monitors. The analysis of the 2001 air samples collected from above the contaminated soil and at two background sites currently is in progress.
Soil-to-Root and Translocation Within Aerial 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 2. It is apparent that different crops accumulate chlordane components differently. Data not shown also indicate that enantiomers translocate differently through plant tissue.
Dose/Response
Zucchini was grown in soil containing four different concentrations of chlordane in bins that were positioned in the field without contacting the field soil itself. To date, the chlordane component concentrations have been determined in the soil before and after planting, and in the zucchini roots. Concentrations in the stems, leaves, and fruit remain to be determined. The soil/root data permit a dose/response to be estimated as shown in Figure 3. The complete data set from the field 2001 dose/response study will be used in the design of dose/response experiments to be conducted in growth chambers in the coming several months.
Future Activities:
Future activities include the design and implementation of dose/response experiments in growth chambers; calculation of soil-to-air flux; and assessment of data from air and vegetation for its impact on human health.Journal Articles on this Report : 2 Displayed | Download in RIS Format
| Other project views: | All 17 publications | 7 publications in selected types | All 7 journal articles |
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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) |
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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) |
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Supplemental Keywords:
atmosphere, soil, chemical transport, health effects, dose-response, measurement methods, environmental chemistry., RFA, Health, Air, Scientific Discipline, Ecosystem Protection/Environmental Exposure & Risk, Waste, Water, Toxics, Susceptibility/Sensitive Population/Genetic Susceptibility, Fate & Transport, pesticides, chemical mixtures, genetic susceptability, Environmental Chemistry, Engineering, Chemistry, & Physics, Contaminated Sediments, tropospheric ozone, Bioavailability, air toxics, Environmental Monitoring, biotic processes, Chlordane (technical mixture and metabolites), contaminant transport, dietary exposure, environmental hazard exposures, sensitive populations, health effects, mass spectrometry, microbial degradation, soil contaminants, weathering, stratospheric ozone, contaminated sediment, human exposure, climate variations, organic soil contaminants, pollutants, atmospheric deposition, insecticides, abiotic processes, chemical contaminants, degradation of organic pollutants, agricultural community, pesticide residues, persistent organic pollutants, exposure, fate and transport, Chlordane, biodegradation, pesticide runoff, sediment transport, chemical transport, agriculture, agrichemicals, persistant organic pollutants, DDT, atmospheric processes, exposure and effectsProgress 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.