Environmental levels of Linear alkylbenzene Sulfonates (LAS) in sediments from the Tagus estuary (Portugal): environmental implications

Abstract

Sediments from the Tagus estuary (Portugal) were collected at 40 stations in July and December 2004. Total LAS concentrations ranged between 0.03 and 17.76 mg LAS.kg(-1) dry weight in July, and between 0.09 and 9.57 mg LAS.kg(-1) in December. Highest LAS concentrations were found at the upper northern part of the estuary, coincident with the localisation of an important waste water treatment station. According to the Predicted No Effect Concentration (PNEC) of 8.1 mg.kg(-1) derived for this compound, Environmental Risk Assessment (ERA) identified a hazard for the ecosystem at the station with the highest LAS concentration, and similar results are obtained by Equilibrium Partitioning Method (EPM). Nevertheless, LAS concentrations decreased significantly between samplings in the stations with the highest LAS concentrations in July, whereas increased LAS concentrations at adjacent stations were found in December. In the remaining stations, LAS concentrations were up to three orders of magnitude lower, representing no hazard for the sediment community.

Seasonal changes in the concentration of anionic surfactants in estuarine sediments from the River Guadalete (Cadiz, Spain)

“…2) and degradation rates consequently increase, in agreement with previous studies conducted in laboratory tests (Quiroga et al, 1999;León et al, 2004) as well as field findings (Inaba and Amano, 1988;Takada et al, 1992). However, Hampel et al (2009) recently found an inverse trend in the Tagus estuary (Portugal), which was mainly attributed to a higher dilution of the LAS input during the winter. In our case, the highest LAS concentrations were detected in the winter of 2001 and the autumn of 2002 (Fig.…”

“…Therefore, in spite of their relatively fast degradation in the receiving waters (Scott and Jones, 2000;León et al, 2004), significant levels of LAS have been reported in aquatic ecosystems (González-Mazo et al, 1998;León et al, 2002;Lara-Martín et al, 2006;Hampel et al, 2009). Concentrations of this surfactant are often much lower in water (usually ranging from less than 1 to 100 μg L -1 ) than in sediments (up to several tens of mg kg -1 in the most contaminated areas), where LAS (especially those homologues having a longer alkyl chain) tend to be accumulated after sorption onto suspended solids, then remaining preserved fairly well under anaerobic conditions.…”

“…Moreover, variations in these inputs can also be monitored because they are reflected in changes in the environmental concentrations of these compounds. Papers dealing with the distribution and seasonal variations of LAS concentration in waters (Takada et al, 1992;González-Mazo et al, 1998;Quiroga et al, 1999) and sediments (Inaba and Amano, 1988;DelValls et al, 2002;Hampel et al, 2009) have in most cases reported the existence of lower values in summer than in winter, mainly due to slower degradation at low temperatures. This trend has been partially confirmed for AES and AS in fresh and marine waters by means of biodegradation laboratory tests (Vashon and Schwab, 1982;Guckert et al, 1996), some of them effectively showing that degradation of these compounds seems to be slower at low temperatures, as well as in non-polluted areas (Quiroga et al, 1999;George, 2002).…”

Selected anionic and cationic surface active agents: case study on the Kłodnica sediments

“…The concentration of individual compounds from the group of LAS for sediments ranged from below MDLs up to ~2100 µg kg -1 . The determined concentration of individual LAS in sediment collected in the Kłodnica catchment area is relatively similar to research conducted in Portugal (Hampel et al 2009). Moreover, the trend that a higher concentration was determined for compounds with longer alkyl chains can clearly be observed.…”

“…This approach is associated with their possible impact on determined values of SAAs using the spectrophotometry technique and their differences in physicochemical properties among the groups (Ying 2006;Nomura et al 1998). In different research centers (USA, Japan, Spain, Portugal, Italy, Austria) determination of selected anionic and cationic surfactants in sediments has been conducted (OECD 2005;Hampel et al 2009;Martinez-Carballo et al 2007;Ferrer and Furlong 2002;Li and Brownawell 2010;Sun et al 2003). In Poland determination of individual surfactants has only been conducted on a relatively limited scale (mainly liquid samples).…”