Chlorinated organic compounds in liquid wastes (DNAPL) from lindane production dumped in landfills in Sabiñanigo (Spain)

Abstract

α, β and γ-hexachlorocyclohexane (HCH) are persistent and bioaccumulative pollutants and they were included in the Stockholm Convention on Persistent Organic Pollutants (POPs). Old lindane factories generated high amounts of wastes with HCH and other Chlorinated Organic Compounds (COCS). These were often dumped in the surroundings of the production sites, polluting soil and groundwaters with the associated risk of surface pollution. This is the case of the Sardas and Bailin landfills, located in Sabiñánigo (Huesca, Spain). Among the waste from lindane production, a liquid residue was detected in the landfill subsurfaces, forming a dense non-aqueous phase liquid (DNAPL) composed of HCH isomers, benzene and chlorobenzenes, with a high impact on groundwater pollution. In this study, six DNAPL samples obtained from the Bailin and Sardas landfills were analyzed by GC/MSD and GC/FID/ECD. Compounds were identified using mass spectra and the retention index from pure standards and literature information. Pure positional isomers of dichlorobenzene (DCB), trichlorobenzene (TCB), tetrachlorobenzene (TetraCB), HCH and pentachlorocyclohexene (PentaCX) were distinguished and quantified. In addition, heptachlorocyclohexane (HeptaCH) isomers, precursors of hexacholorocylohexene (HexaCX), were also identified and quantified in the DNAPL samples, although the corresponding isomers could not be discriminated. Information about PentaCX, HexaCx and HeptaCH identification is very limited in the literature. HCH contents in the DNAPL ranged from 22% to 30% in weight, the major isomers being lindane and δ-HCH, followed by α-HCH. The β isomer was the least abundant. HeptaCH contents were present in the same order of magnitude as HCHs in the DNAPL. PentaCXs and HexaCXs could have appeared as dehydrochlorination derivatives of HCHs and HeptaCHs, respectively. Two of the DNAPLs analyzed showed a higher content of TCBs and TetraCBs, associated with lower HCH and HeptaCH contents. Variations of these compounds in the DNAPL could be related to an alkaline dehydrochlorination in the landfill conditions.

Soil flushing pilot test in a landfill polluted with liquid organic wastes from lindane production

“…This is in agreement with the appearance of a free dense organic phase in PS14D in the alluvial-marl contact when the borehole was drilled, as explained in the experimental phase. The composition and aspect of this free DNAPL is shown in Table SI-3 and was similar to other DNAPLs from the site previously analyzed (Santos et al., 2018). In Table SI-3, the acronym of each COC is also provided.…”

“…To do this, a calibration of limonene was made preparing solutions of this compound (purchased to Sigma-Aldrich, analytical grade) in methanol. Limonene was eluted between 1,4 DCB and 1,2 DCB, as can be seen in the GC/FID chromatogram shown elsewhere (Santos et al., 2018). A mass percentage of limonene in the commercial surfactant-cosolvent mixture E-Mulse 3 ® about 15% was determined using this calibrate.…”

“…The analytical methods for COCs quantification were developed elsewhere (Santos et al., 2018). The same methods for GC/MSD and GC/FID/ECD analysis than those reported in the previous work have been used here with the only difference that in the present case the injection volume was 2 μL instead 1 μL.…”

“…The residue was dumped some decades ago in two landfills near the production site: Bailin and Sardas. About thirty chlorinated organic compounds (COCs), from chlorobenzene to heptachlorocyclohexane, were identified in this DNAPL (Santos et al., 2018) with a density of about 1.5 g cm −3 . This dense phase has migrated through the subsurface, affecting the alluvial deposits hydraulically linked to the Gallego River (Fernández et al., 2013).…”

Wet Peroxide Oxidation of Chlorobenzenes Catalyzed by Goethite and Promoted by Hydroxylamine

“…The output flow of the capillary column was split (1:1), using FID and ECD detectors simultaneously. More details of the experimental procedure can be found elsewhere [18].…”