Long-Term Spatio-Temporal Trends of Organotin Contaminations in the Marine Environment of Hong Kong

Overview

Ho and colleagues measured six organotin compounds in the rock shell Reishia clavigera along Hong Kong coastal waters in 2010 and 2015, with supporting seawater and sediment measurements. This is wild gastropod biomonitoring evidence, not a Hong Kong market-seafood survey, but it reports shellfish-tissue organotin concentrations with dry-weight and wet-weight tin-equivalent ranges. The source keeps butyltins, phenyltins, and total organotins distinct and should not be treated as total elemental tin or inorganic tin.

Key numbers

The study collected about 40 adult R. clavigera per site from 29 rocky-shore sites in May to September 2010 and repeated sampling at 10 selected shores in July and August 2015. Shell lengths were >= 17 mm, with actual shell lengths between 23 and 36 mm; the authors state that no depuration was conducted.

Rock-shell tissue from each site was pooled into 3 or 4 analytical replicates, each containing 8-15 individuals.

Tissue concentrations of total organotins in R. clavigera ranged from 318.5-11,278.9 μg kg-1 dw in 2010, equivalent to 24.2-769.0 μg Sn kg-1 wet weight (ww). In 2015, total organotins ranged from 643.9-15,304.9 μg kg-1 dw, equivalent to 46.5-1039.4 μg Sn kg-1 ww.

Triphenyltin (TPT) ranged from 227.9-11,108.0 μg kg-1 dw in 2010, equivalent to 15.4-751.4 μg Sn kg-1 ww. In 2015, TPT ranged from 612.4 to 15,059.6 μg kg-1 dw, equivalent to 41.4-1,018.6 μg Sn kg-1 ww.

TPT was the predominant residue, accounting for 46-99% of total organotins in 2010 and 90-98% in 2015.

Tributyltin (TBT) ranged from 5.8 to 422.0 μg kg-1 dw in 2010, equivalent to 0.5-34.5 μg Sn kg-1 ww. In 2015, TBT ranged from below detection limit to 117.3 μg kg-1 dw, equivalent to below detection limit-9.6 μg Sn kg-1 ww.

The paper reports that 18 out of 26 sites had butyltin degradation index (BDI) below 1 in 2010, while 9 out of 10 sites in 2015 showed BDI > 1. All sites showed phenyltin degradation index (PDI) below 1 in 2010 except Chek Chau, and all sites fell below 1 in 2015.

For temporal comparisons, tissue TBT concentrations significantly increased between 2004-2006 and 2010 (t = 3.637, p < 0.001) and decreased from 2010 to 2015 (Z = -2.803, p < 0.01). TPT and total organotin concentrations remained similar between 2010 and 2015 (Z = 0.866, p > 0.05).

The ecological risk assessment reported a 17.6% chance that local R. clavigera collected in 2010 were at risk from phenyltin exposure (RQ >= 1), increasing to 69.4% in 2015. For butyltins, the reported risk chance decreased from 1.6% in 2004 to 0.7% in 2010, then increased to 3.4% in 2015.

Method performance values were recovery rates of 64.6%-93.5% for the six organotins except DPT, detection limits of 0.2-1.5 μg kg-1 dry weight (dw) for tissue and sediment samples, and detection limits of 0.4-2.6 ng L-1 for water samples except 29.1 ng L-1 for MBT. The authors report all concentrations without correction to recovery rates.

Methods (brief)

The authors collected adult R. clavigera from Hong Kong rocky shores, with paired seawater and sediment sampling at selected stations. They quantified six organotins (MBT, DBT, TBT, MPT, DPT, and TPT) using a gas chromatograph (Agilent 6890) with mass-selective detector (Agilent 5973) and a DB-5MS capillary column after published extraction/cleanup methods for rock shell, sediment, and water. Rock-shell tissue was pooled by site before analysis. The source reports tissue and sediment values as μg kg-1 dry weight, provides wet-weight tin-equivalent tissue ranges, and does not report total elemental tin (Sn) or inorganic tin.

Implications

This source contributes Hong Kong shellfish-organotin context for wild gastropod tissue, especially TPT and TBT in R. clavigera. Because the sampled organisms were collected as coastal biomonitors rather than as market seafood, downstream routing should treat the values as environmental shellfish-tissue context and should not merge them with market-seafood occurrence pools without explicit row-fit adjudication. The tin evidence is organotin-species evidence only; TPT, TBT, butyltins, phenyltins, and total organotins must remain distinct from total Sn and inorganic Sn.

Update history

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