The environmental behaviour and toxicological effect of propetamphos in an estuarine environment.

Abstract

Inorganic and organic characterisation of water and sediment from five sites along the Conwy River and Estuary (CRE) was carried out. Sequential extraction
showed 90 to 100% of metal content in sediment and suspended particulate matter (SPM) to be bound to organic and mineral fractions. High concentrations of Zn and Fe were found in pore water throughout CRE (Pb was found in river sediment pore water). Zn and Fe exhibited conservative behaviour indicating that the estuary was a sink for them. Mn and Al presented non conservative trends; a
potential source for Al was identified as Dolgarrog Aluminium. Trace levels of
selected metals from along the Estuary were analysed using a pre-concentration
procedure and ICP-OES analysis validated as part of this work.
Dissolved natural organic matter (NOM) was characterised by total phenol, DOC, "weight-averaged molecular weight" (MW) and UV-visible spectroscopy. One MW distribution was generally found (<1100); two in Autumn. Positive, linear correlations were found between MW and total phenol, the humification ratio (E₄/E₆) and DOC and negatively with molar absorptivity (ε). DOC and ε correlated following an exponential decay model. Correlations between metals and Suwannee River NOM showed Ca and Na preferentially in the high MW fraction, Mg and K with medium MW fractions and Zn with in low MW fraction.
The behaviour and fate of propetamphos (PPT) was tested in the presence of NOM, salinity and metals in sediment from the CRE. Initially PPT was rapidly
sorbed onto sediment, then more slowly (<50% sorbed after 8 hrs). Freundlich
coefficients (K_f) correlated with sediment organic matter. PPT was readily
biodegraded by the microbial sediment population from the CRE. Biodegradation
was reduced considerably with higher salinity or metal ions. PPT reduced
sediment microbial glucose respiration. Toxic effects of equimolar binary and
ternary combinations of PPT with metals (Zn, Pb) were additive. NOM decreased
toxic effects but only slightly. The toxic effect of commercial PPT was 162 times
greater than pme PPT based on EC₁₀ values.

Date of Award	Oct 2002
Original language	English
Awarding Institution	University of Wales, Bangor
Sponsors	Consejo Nacional de Ciencia y Tecnologia (CONACYT)
Supervisor	Peter Holliman (Supervisor) & Davey Jones (Supervisor)