174 Organic compounds in soils, sediments & sludges
sediments generates tetramethyllead: that Me 3 Pb
+ salts are readily converted to tetramethyllead by microorganisms in lake water or nutrient medium, with or without the
sediment, and in the presence or the absence of light; that conversion of inorganic lead
(such as lead nitrate or lead chloride) to tetramethyllead occurred on several occasions
in the presence of certain sediments; and that the conversion is purely a biological
process.
Detection limits achievable in the determination of organolead compounds in
sediments range from 0.01 mg kg
−1 [4, 5] to 0.00001 mg kg
−1 [11].
7.3 ORGANOTIN COMPOUNDS
Various workers have discussed the determination of alkyl and aryl compounds in
sediments.
Nemomic et al [12] have carried out a critical evaluation of various extraction
procedures for the speciation of butyltin compounds in sediments.
Ebdon et al [13] have discussed a programme to improve the quality of analytical
results in the environmental monitoring of organotin compounds. They discuss the
evaluation of a sensitive, reliable and robust analytical method for the determination
of tributyltin, with emphasis on the difficulties of determining it at the ng per litre levels
at which it was usually encountered, more especially as other forms of tin frequently
occurred together at similar levels. The preparation of a standard reference sample, for
use in inter-laboratory comparative determinations, under the aegis of the Bureau of
Community Reference of the EU is described, and plans for subsequent distributions
of blank, artificially spiked, and genuinely affected sediments are sketched.
Three groups have independently reported on the methylation of both inorganic
tin and organotin substrates by the mixed populations of microbial flora present in
sediments collected from a Canadian fresh water lake [14], and from estuarine sites in
San Francisco Bay and Chesapeake Bay [15–17]. Biogenesis of Me 4 Sn was seen only
to occur with additions of Me 3 Sn
+ to incubated sediments [14, 18], but redistribution
reactions of intermediate methyltins to form Me 4 Sn by non-biological pathways must
be noted as competitive events in such experiments [18, 19]. The concentrations of
tin compounds added to incubated sediments were consistent with values found in
polluted sediments. The influence of other bioactive pollutant metals also commonly
found in such sediments was not investigated.
A relatively recent sediment (period 1980–1984) and a sediment from the late
nineteenth century (1880–1885) taken from Lake Zurich were investigated. No
organotin compounds could be detected in the 1880 sediment, but a series of organotin compounds ranging from 280 µg kg
−1 tributylin to 10 mg kg
−1 dichlorhexyltin
were present in the recent sediment. The main components were again the butyltin
compounds, indicating their frequent use, persistence and bioaccumulative power.
Cyhex 2 Sn
2+ and Cyhex 3 Sn
+ were also identified, reflecting the use of the parent compound, trichlorhexyltin as a miticide in the region around Lake Zurich. The absence
of organotin resides in the 1880 sediment is explained by the fact that technical use of
these compounds started after 1936. The residue found in the recent sediment are considerably higher than those detected in surface sediment from the lower basin. As the
sedimentation near the effluent of Lake Zurich in the shallow and oxygen-saturated
water is dominated by processes leading to resuspension and oxidation of the fine,
sediments generates tetramethyllead: that Me 3 Pb
+ salts are readily converted to tetramethyllead by microorganisms in lake water or nutrient medium, with or without the
sediment, and in the presence or the absence of light; that conversion of inorganic lead
(such as lead nitrate or lead chloride) to tetramethyllead occurred on several occasions
in the presence of certain sediments; and that the conversion is purely a biological
process.
Detection limits achievable in the determination of organolead compounds in
sediments range from 0.01 mg kg
−1 [4, 5] to 0.00001 mg kg
−1 [11].
7.3 ORGANOTIN COMPOUNDS
Various workers have discussed the determination of alkyl and aryl compounds in
sediments.
Nemomic et al [12] have carried out a critical evaluation of various extraction
procedures for the speciation of butyltin compounds in sediments.
Ebdon et al [13] have discussed a programme to improve the quality of analytical
results in the environmental monitoring of organotin compounds. They discuss the
evaluation of a sensitive, reliable and robust analytical method for the determination
of tributyltin, with emphasis on the difficulties of determining it at the ng per litre levels
at which it was usually encountered, more especially as other forms of tin frequently
occurred together at similar levels. The preparation of a standard reference sample, for
use in inter-laboratory comparative determinations, under the aegis of the Bureau of
Community Reference of the EU is described, and plans for subsequent distributions
of blank, artificially spiked, and genuinely affected sediments are sketched.
Three groups have independently reported on the methylation of both inorganic
tin and organotin substrates by the mixed populations of microbial flora present in
sediments collected from a Canadian fresh water lake [14], and from estuarine sites in
San Francisco Bay and Chesapeake Bay [15–17]. Biogenesis of Me 4 Sn was seen only
to occur with additions of Me 3 Sn
+ to incubated sediments [14, 18], but redistribution
reactions of intermediate methyltins to form Me 4 Sn by non-biological pathways must
be noted as competitive events in such experiments [18, 19]. The concentrations of
tin compounds added to incubated sediments were consistent with values found in
polluted sediments. The influence of other bioactive pollutant metals also commonly
found in such sediments was not investigated.
A relatively recent sediment (period 1980–1984) and a sediment from the late
nineteenth century (1880–1885) taken from Lake Zurich were investigated. No
organotin compounds could be detected in the 1880 sediment, but a series of organotin compounds ranging from 280 µg kg
−1 tributylin to 10 mg kg
−1 dichlorhexyltin
were present in the recent sediment. The main components were again the butyltin
compounds, indicating their frequent use, persistence and bioaccumulative power.
Cyhex 2 Sn
2+ and Cyhex 3 Sn
+ were also identified, reflecting the use of the parent compound, trichlorhexyltin as a miticide in the region around Lake Zurich. The absence
of organotin resides in the 1880 sediment is explained by the fact that technical use of
these compounds started after 1936. The residue found in the recent sediment are considerably higher than those detected in surface sediment from the lower basin. As the
sedimentation near the effluent of Lake Zurich in the shallow and oxygen-saturated
water is dominated by processes leading to resuspension and oxidation of the fine,