Persistent Organic Pollutants in the Environment

Abstract

The half-lives of some persistent organic pollutants (POPs) in environmental compartments such as soil and air can be as long as decades. In spite of the hydrophobicity of many POPs, the literature contains reports of their uptake by, and translocation through, a variety of plants. Both these observations prompt the investigation of whether a vegetation-based environmental compartment such as compost contains significant residues of POPs. Previous reports imply that residues of technical chlordane will be found in compost. Due to its physicochemical properties, technical chlordane provides insights into the fate of POPs in the environment, which are not accessible through determinations of other pollutants in this group. Accordingly, we undertook the first comprehensive examination of technical chlordane residues in a variety of composts, specifically, 13 commercial and 39 municipal compost products, to both characterize and quantify the magnitude of this point source of contamination. Using chiral gas chromatography interfaced to ion trap mass spectrometry, the concentration and the compositional and enantiomeric profiles of chlordane components were determined. Of the 13 commercial products, 9 contained detectable chlordane concentrations, ranging from 4.7 to 292 microg/kg (dry wt.), while all 39 municipal products contained chlordane residues ranging from 13.9 to 415 microg/kg (dry wt.). The residue concentrations and profiles suggest possible feedstock sources for the chlordane in the finished compost product. The data also support the conclusion that some composts contribute to anthropogenic cycling of POPs through the biosphere.

Subspecies-Level Variation in the Phytoextraction of Weathered p,p‘-DDE by Cucurbita pepo

“…The biomass values and intraplant contaminant distribution reported here are similar to our previous findings for the uptake and translocation of weathered chlordane and p,p′-DDE by C. pepo (34,44). In addition, the percent of contaminant phytoextracted also fits within the range previously reported.…”

“…Table 2 shows that several indices of contaminant uptake and translocation are significantly greater for ssp pepo than for ssp texana. Our previous studies focused on a narrow range of cultivars within ssp pepo and have consistently reported significant phytoextraction of weathered chlordane (44,49) and p,p′-DDE (33,34). As described above, White (34) did show different uptake potentials of p,p′-DDE for a small number of cultivars of ssp texana and pepo.…”

“…As described above, White (34) did show different uptake potentials of p,p′-DDE for a small number of cultivars of ssp texana and pepo. We have speculated that these differential patterns of POP uptake and translocation are the result of variable patterns of root exudation (34,44,50). Subspecies-level variation in both root exudate quantity and composition has been observed.…”

“…Figure 2 shows the relationship between P and p,p′-DDE BCFs in the roots and stems of both subspecies. Although there is some scatter in the data, the two subspecies of plants appear to group separately, indicating that ssp pepo is more efficient than texana at phytoextracting both weathered p,p′-DDE and P. We have previously hypothesized that the unique phytoextraction abilities of C. pepo (specifically ssp pepo) are the result of a phosphorus acquisition mechanism involving the root exudation of low molecular weight organic acids (LMWOA) (44,50). Di-and tricarboxylic acids can chelate and extract inorganic elements from the soil structure, effectively loosening the solid matrix and increasing P availability (55,56).…”

Environmental Mass Spectrometry: Emerging Contaminants and Current Issues

“…In addition, significant shifts in the compositional profile and chiral profile were observed in the plant tissues. In another study by the same group, chiral GC/ion trap-MS was used to examine technical chlordane residues in a variety of compost products (13 commercial and 39 municipal) (119). Compositional and enantiomeric profiles were obtained.…”