M. Radojevic

Concentrations and pathways of organolead compounds in the environment: A review

Concentrations of organolead compounds determined in air, water, biological and other environmental samples are reviewed, together with the results of laboratory studies into the environmental chemistry of these species. Particular emphasis is placed on recent investigations which have employed species-specific gas chromatography/atomic absorption spectroscopy (GC/AAS) for analysis. Ionic alkyllead species (R3Pb+ and R2Pb2+) are found to be fairly persistent intermediates in the environmental decomposition of tetraalkyllead (R4Pb) compounds.

Determination of tetraalkyl and ionic alkyllead compounds in environmental samples by butylation and gas chromatography‐atomic absorption

Abstract A technique for the simultaneous determination of tetraalkyl‐ and ionic alkyl‐lead species in environmental samples is reported. Alkyllead species are extracted into n‐hexane in the presence of NaDDTC and NaCl. The extracts are butylated and analysed by gas chromatography‐atomlc absorption (GC/AA). Detection limits for individual TAL and TriAL compounds are of the order of. ng I‐1 in aqueous samples, pg m‐3 in atmospheric aerosols and ng g‐1 in street dusts. Alkyllead compounds have been quantified ‐in rainwater, atmospheric aerosols and motorway runoff water with this technique and representative results are reported.

Atmospheric speciation and wet deposition of alkyllead compounds

Concentrations of individual tetra-, tri-, and dialkyllead compounds have been measured in the gas phase and in aerosol and rainwater samples at two sites in eastern England and at one site in western Ireland. The results show a predominance of gas-phase over aerosol-associated species in the air at all sites, and in general a greater abundance of tetraalkyllead than trialkyllead. Washout factors for total alkyllead are lower than for inorganic lead and correlate highly between adjacent urban and semirural sites.

Concentrations, speciation and decomposition of organolead compounds in rainwater

Abstract Tetraalkyllead (R 4 Pb), trialkyllead (R 3 Pb + ) and dialkyllead (R 3 Pb 2+ ) compounds were determined in rainwater collected at urban, semi-rural and rural sites using gas chromatography/atomic absorption spectroscopy (GC/AAS). At sites in England, total organolead concentrations in the range of 10–928 ng Pb l −1 were found in rainwater and ratios of organic to inorganic lead were between ng Pb l −1 R 3 Pb + species containing mixed alkyl groups were also observed. At a semi-rural site in Southeast England the deposition rate for total organic lead was 5.6 ng Pb cm −2 year −1 . No consistent seasonal variation ol alkyllead species or concentration was noted. Stability tests revealed that R 4 Pb compounds decompose quantitatively within 48 h to R 3 Pb + species in rainwater samples left in the field during sampling programmes. R 3 Pb + and R 2 Pb 2+ compounds were found to be very stable in rainwater samples left in the dark.

Measurements of alkyllead compounds in the gas and aerosol phase in urban and rural atmospheres

Alkyllead compounds in the gas and aerosol phase were determined simultaneously in urban and rural atmospheres using gas chromatography--atomic absorption spectroscopy and wet chemical (iodine monochloride) methods. The difference in results between the two methods suggests the presence of vapour-phase tri- (and/or di-)alkyllead in both urban and rural air. Concentrations of 0.06-1.6 and 16-205 ng Pb m-3 were found for vapour-phase organolead compounds other than tetraalkyllead in rural and kerbside urban air, respectively. Tetraalkyllead and trialkyllead compounds were identified in atmospheric aerosols at both sites, but these were found to be present at concentrations less than 1.2% of the total gas-phase alkyllead.

The determination of individual gaseous ionic alkyllead species in the atmosphere

Abstract Gaseous ionic alkyllead species (in the ng Pb m−3 range) are collected from air by absorption in water. After extraction into n-hexane, they are propylated or butylated and quantified by gas chromatography/electrothermal atomic absorption spectrometry. Interference from inorganic lead compounds and aerosol-phase alkyllead compounds is entirely absent, whilst that from tetraalkyllead compounds is small and generally negligible. This method allows the unequivocal identification of gaseous ionic alkyllead species in the atmosphere.

The chemical composition of highway drainage waters IV. Alkyllead compounds in runoff waters

Abstract Alkyllead compounds have been analysed in road drainage water samples collected during seven storm events using a sensitive gas chromatography-atomic absorption technique. The most commonly observed alkyllead species were tetraethyllead, triethyllead and trimethyllead. Similar compounds were also observed in rainwater collected at the site, but not in road surface dust or bottom sediment from the drainage channel. In all samples analysed the concentration of alkyllead was

Alkyllead compounds in surface and potable waters

Abstract Gas chromatography/atomic absorption spectrometry was used to determine specific alkyllead compounds in surface and potable water samples. For the first time ionic alkyllead species were identified in potable waters at very low levels with concentrations up to 4 ng Pb 1‐1. No tetraalkyllead compounds were found in any of the samples analysed and laboratory studies demonstrated that these species decompose rapidly in aqueous samples to trialkyl lead, the most common form of organic lead in environmental samples.

Alkyllead compounds in dust, sediment and soil samples

Abstract Gas chromatography/atomic absorption spectrometry was used to determine specific alkyllead compounds in dust, sediment and soil samples. There was considerable variation in the species and concentration of alkyllead in these samples with highest concentrations being of the order of tens of ng Pb g‐1. This is insignificant compared to the inorganic lead concentrations widely reported for polluted dust and soil samples of the order of 102‐103 μg Pb g‐1.