Marine risk assessment: linear alkylbenzenesulponates (LAS) in the North Sea

Ecological risk assessment of heavy metals in varied matrices of coastal environment of Maharashtra, India, and their effects on forked venus clam, Gafrarium divaricatum (Gmelin, 1791)

The spatial and seasonal variation of heavy metal contamination was assessed in the seawater, sediments, and clam samples collected from Ratnagiri, Bandra, and Aksa Beach, along Maharashtra Coast, India, during the different seasons. The concentrations of eleven heavy metals were analyzed using inductively coupled plasma-atomic emission spectroscopy (ICP-AES), and the metal concentrations were found in the order sediment > clam > seawater. Various pollution indices indicated that Cd and As mainly contributed to ecological risks, and Bandra was the most contaminated site. Bioaccumulation studies in intertidal clam, Gafrarium divaricatum (Gmelin, 1791), showed that most heavy metals exceeded permissible limits except Cu and Zn. Histopathological examination of the clam tissues revealed hemocyte infiltration, damage in cilia and lamellae of the gills, tubular atrophy, and necrosis in the digestive glands. The findings of this research highlight the potential of G. divaricatum as a reliable bioindicator species for biomonitoring and sustainable management of coastal ecosystems.

Exploring micropollutants in polar environments based on non-target analysis using LC-HRMS

The routine use of chemicals in polar regions contributes to unexpected occurrence of micropollutants, with sewage discharge as a prominent pollution source. The aim of this study was to identify and quantify micropollutants in polar environments near potential point sources using non-target analysis (NTA) with liquid chromatography high-resolution mass spectrometry. Seawater samples were collected from Ny-Ålesund, Svalbard and Marian Cove, King George Island, in 2023. We tentatively identified 32 compounds with NTA, along with 105 homologous series substances. Of these, 18 substances were confirmed, and 13 were quantified using the internal standard method. Most quantified substances in the Ny-Ålesund, including caffeine, naproxen, and polyethylene glycols (PEGs), exhibited concentrations ranged from 0.9 to 770,000 ng/L. In Marian Cove, the analysis predominantly detected acetaminophen, with concentrations ranging from 13 to 35 ng/L. The findings underscore the presence and spatial distribution of emerging micropollutants resulting from wastewater discharge in polar regions.

Growth and physiological responses of submerged macrophytes to linear alkylbenzene sulfonate (LAS)

The potential toxic effects of linear alkylbenzene sulfonate (LAS), widely used in commercial detergents and cleaners, on submerged macrophytes remain unclear. We conducted a two-week exposure experiment to investigate LAS toxicity on five submerged macrophytes (four native and one exotic), focusing on their growth and physiological responses. The results showed that lower concentrations of LAS (< 5 mg/L) slightly stimulated the growth of submerged macrophytes, while higher doses inhibited it. Increasing LAS concentration resulted in decreased chlorophyll content, increased MDA content and POD activity, and initially increased SOD and CAT activities before declining. Moreover, Elodea nuttallii required a higher effective concentration for growth compared to native macrophytes. These findings suggest that different species of submerged macrophytes exhibited specific responses to LAS, with high doses (exceeding 5 ∼ 10 mg/L) inhibited plant growth and physiology. However, LAS may promote the dominance of surfactant-tolerant exotic submerged macrophytes in polluted aquatic environments.

Biomonitoring of heavy metals accumulation in molluscs and echinoderms collected from southern coastal India

Distribution of five heavy metals (Cd, Cr, Cu, Pb, and Zn) in molluscan and echinoderm species collected from Kerala and Gulf of Mannar in Southern India is presented. Atomic absorption spectrometry was used to determine metal concentrations. Concentrations of metals showed a descending order of Zn > Cu > Pb > Cd > Cr. Zn and Cu might have originated from both natural and man-made sources. However, Cd, Cr, and Pb could have strong anthropogenic influences such as harbour activities and untreated industrial and agricultural runoff. Bioaccumulation factor (BAF) value of Cd in two edible bivalves from Munambam is slightly greater than one. Regular consumption of Cd-loaded shellfish can cause serious health hazards and concerns to humans. BAF results showed that Zn, Cu, Pb, and Cd were more bioaccumulated and beyond the threshold limits in certain species. It is evident that consumption of shellfish from the Kerala coastal waters may have adverse health impacts to the consumers.

Screening the baseline fish bioconcentration factor of various types of surfactants using phospholipid binding data

Fish bioconcentration factors (BCFs) are commonly used in chemical hazard and risk assessment. For neutral organic chemicals BCFs are positively correlated with the octanol-water partition ratio (K_OW), but K_OW is not a reliable parameter for surfactants. Membrane lipid-water distribution ratios (D_MLW) can be accurately measured for all kinds of surfactants, using phospholipid-based sorbents. This study first demonstrates that D_MLW values for ionic surfactants are more than 100 000 times higher than the partition ratio to fish-oil, representing neutral storage lipid. A non-ionic alcohol ethoxylate surfactant showed almost equal affinity for both lipid types. Accordingly, a baseline screening BCF value for surfactants (BCF_baseline) can be approximated for ionic surfactants by multiplying D_MLW by the phospholipid fraction in tissue, and for non-ionic surfactants by multiplying D_MLW by the total lipid fraction. We measured D_MLW values for surfactant structures, including linear and branched alkylbenzenesulfonates, an alkylsulfoacetate and an alkylethersulfate, bis(2-ethylhexyl)-surfactants (e.g., docusate), zwitterionic alkylbetaines and alkylamine-oxides, and a polyprotic diamine. Together with sixty previously published D_MLW values for surfactants, structure-activity relationships were derived to elucidate the influence of surfactant specific molecular features on D_MLW. For 23 surfactant types, we established the alkyl chain length at which BCF_baseline would exceed the EU REACH bioaccumulation (B) threshold of 2000 L kg^-1, and would therefore require higher tier assessments to further refine the BCF estimate. Finally, the derived BCF_baseline are compared with measured literature in vivo BCF data where available, suggesting that refinements, most notably reliable estimates of biotransformation rates, are needed for most surfactant types.

Occurrence and potential environmental risk of surfactants and their transformation products discharged by wastewater treatment plants

Seven-day composite effluent samples from a German monitoring campaign including 33 conventional wastewater treatment plants (WWTP) were analyzed for linear alkylbenzene sulfonates (LAS) and alkyl ethoxysulfates (AES) and were screened by wide-scope suspect screening for 1564 surfactants and their transformation products (TPs) by UHPLC-ESI-QTOF-MS. Corresponding seven-day composite influent samples of selected WWTPs showed high influent concentrations as well as very high removal rates for LAS and AES. However, average total LAS and AES effluent concentrations were still 14.4 μg/L and 0.57 μg/L, respectively. The LAS-byproducts di-alkyl tetralin sulfonates (DATSs), the TPs sulfophenyl alkyl carboxylic acids (SPACs) and sulfo-tetralin alkyl carboxylic acids (STACs) reached maximum effluent concentrations of 19 μg/L, 17 μg/L and 5.3 μg/L, respectively. In many cases the sum of the concentration of all LAS-related byproducts and TPs surpassed the concentration of the precursors. High concentrations of up to 7.4 μg/L were found for 41 polyethylenoglycol homologs. Quantified surfactants and their TPs and by-products together accounted for concentrations up to 82 μg/L in WWTP effluents. To determine the risk of individual surfactants and their mixtures, single homologs were grouped by a "weighted carbon number approach" to derive normalized Predicted No-Effect Concentrations (PNEC), based on experimental ecotoxicity data from existing risk assessments, complemented by suitable Quantitative Structure-Activity Relationships (QSAR) predictions. Predicted Environmental Concentrations (PEC) were derived by dividing effluent concentrations of surfactants by local dilution factors. Risks for all analyzed surfactants were below the commonly accepted PEC/PNEC ratio of 1 for single compounds, while contributions to mixture toxicity effects from background levels of LAS and DATS cannot be excluded. Maximum LAS concentrations exceeded half of its PNEC, which may trigger country-wide screening to investigate potential environmental risks.

Comprehensive review of several surfactants in marine environments: Fate and ecotoxicity

Surfactants are a commercially important group of chemicals widely used on a global scale. Despite high removal efficiencies during wastewater treatment, their high consumption volumes mean that a certain fraction will always enter aquatic ecosystems, with marine environments being the ultimate sites of deposition. Consequently, surfactants have been detected within marine waters and sediments. However, aquatic environmental studies have mostly focused on the freshwater environment, and marine studies are considerably underrepresented by comparison. The present review aims to provide a summary of current marine environmental fate (monitoring, biodegradation, and bioconcentration) and effects data of 5 key surfactant groups: linear alkylbenzene sulfonates, alcohol ethoxysulfates, alkyl sulfates, alcohol ethoxylates, and ditallow dimethyl ammonium chloride. Monitoring data are currently limited, especially for alcohol ethoxysulfates and alkyl sulfates. Biodegradation was shown to be considerably slower under marine conditions, whereas ecotoxicity studies suggest that marine species are approximately equally as sensitive to these surfactants as freshwater species. Marine bioconcentration studies are almost nonexistent. Current gaps within the literature are presented, thereby highlighting research areas where additional marine studies should focus.

Physiological Response of the Hard Coral Pocillopora verrucosa from Lombok, Indonesia, to Two Common Pollutants in Combination with High Temperature

Knowledge on interactive effects of global (e.g. ocean warming) and local stressors (e.g. pollution) is needed to develop appropriate management strategies for coral reefs. Surfactants and diesel are common coastal pollutants, but knowledge of their effects on hard corals as key reef ecosystem engineers is scarce. This study thus investigated the physiological reaction of Pocillopora verrucosa from Lombok, Indonesia, to exposure with a) the water-soluble fraction of diesel (determined by total polycyclic aromatic hydrocarbons (PAH); 0.69 ± 0.14 mg L-1), b) the surfactant linear alkylbenzene sulfonate (LAS; 0.95 ± 0.02 mg L-1) and c) combinations of each pollutant with high temperature (+3°C). To determine effects on metabolism, respiration, photosynthetic efficiency and coral tissue health were measured. Findings revealed no significant effects of diesel, while LAS resulted in severe coral tissue losses (16-95% after 84 h). High temperature led to an increase in photosynthetic yield of corals after 48 h compared to the control treatment, but no difference was detected thereafter. In combination, diesel and high temperature significantly increased coral dark respiration, whereas LAS and high temperature caused higher tissue losses (81-100% after 84 h) and indicated a severe decline in maximum quantum yield. These results confirm the hypothesized combined effects of high temperature with either of the two investigated pollutants. Our study demonstrates the importance of reducing import of these pollutants in coastal areas in future adaptive reef management, particularly in the context of ocean warming.

Bioconcentration of the anionic surfactant linear alkylbenzene sulfonate (LAS) in the marine shrimp Palaemonetes varians: a radiotracer study

Uptake and depuration kinetics of dissolved [(14)C]C₁₂-6-linear alkylbenzene sulfonate (LAS) were determined in the shrimp Palaemonetes varians using environmentally relevant exposure concentration. The shrimp concentrated LAS from seawater with a mean BCF value of 120 L kg(-1) after a 7-day exposure. Uptake biokinetics were best described by a saturation model, with an estimated BCFss, of 159 ± 34 L kg(-1), reached after 11.5 days. Shrimp weight influenced significantly BCF value with smaller individuals presenting higher affinity to LAS. To the light of a whole body autoradiography, major accumulation of LAS occurred in the cephalothorax circulatory system (gills, heart, hepatopancreas) and ocular peduncle, but not in the flesh, limiting potential transfer to human consumers. LAS depuration rate constant value of the shrimp was 1.18 ± 0.08 d(-1) leading to less than 1% of remaining LAS in its tissues after 8 days of depuration.

Automated Determination of Linear Alkylbenzene Sulphonate (LAS) in Wastewater Treatment Plants Effluents Using on Line Solid-phase Extraction Followed by HPLC with Fluorescence Detection

An on line SPE (solid-phase extraction) method followed by HPLC with fluorescence detection has been developed and validated for determining the LAS in inlet and outlet effluents of wastewaters treatment plants. Filtered effluent samples were on line concentrated on a small polymeric reversed phase column, then the trapped LAS are separated on a specialty polar-embedded reversed-phase column and detected by a fluorimeter. The on line SPE method with fluorescence detection showed very good repeatability (from 1.5 to 11.7% depending on the sample loading volume) and robustness with detection limits of 1.5 μg l−1 for total C10–13 LAS loading a 5 ml sample volume. This automated method is a cost-effective way to determine LAS also in routine monitoring of inlets and outlets of wastewater treatment plants allowing to optimize treatment procedures.

Environmental monitoring of linear alkylbenzene sulfonates and physicochemical characteristics of seawater in El-Mex Bay (Alexandria, Egypt)

In the present work, the influence of different physicochemical characteristics on the distribution of anionic detergents, linear alkylbenzene sulfonates (LAS), was studied. Surface and bottom water samples were collected from eight different sites from a small bay near the main sewage discharge of Alexandria City (El-Max Bay). The results showed great variations in the concentrations, as a function of the regional and seasonal variations. The study revealed that the pH values lie in the normal side, with a range of 8.0-8.5 inside the bay and 7.5-7.7 at El-Umum Drain effluent. Wide variations, observed between the surface and the bottom water of the bay, salinity, dissolved oxygen, oxidizable organic matter, total hardness, and total alkalinity, were scattered in the ranges (3.33-42.73 practical salinity unit), (0.42-8.27 mg O2/l), (0.12-10.49 mg/l), (1.39-8.99 mg/l), and (0.23-0.48 mg/l), respectively. The regional variations of LAS concentrations in the bay waters showed that the concentration decreased as the distance from the source of drainage water (El-Umum Drain). The seasonal average variations of LAS cleared out that summer and spring periods had the highest concentrations at surface (0.13 ± 0.04 mg LAS/l) and bottom (0.12 ± 0.10 mg LAS/l) layer, which is attributed to increase in population density and human activities. The inverse relationships between total LAS concentration and salinity, dissolved oxygen, and calcium ions concentration are r = -0.78, 0.50, and 0.67, respectively. This is related to the occurrence of the untreated wastewater containing detergents, the biodegradation rate of surfactants, and strong precipitation of LAS as Ca.

Anionic surfactant linear alkylbenzene sulfonates (LAS) in sediments from the Gulf of Gdańsk (southern Baltic Sea, Poland) and its environmental implications

Linear alkylbenzene sulfonate (LAS) is a group of anionic surfactants employed in the formulation of laundry and cleaning products, with a global production rate of 4 million metric tons. Sediments from the Polish coast of the southern Baltic Sea were collected at ten stations. Total LAS concentrations, measured by high-performance liquid chromatography, were between 0.04 and 0.72 mg LAS·kg(-1) dry weight. Highest LAS concentrations were found in suspended matter collected from the Vistula River, sediment collected close to the Vistula River mouth and from the Gdańsk Deep, known as the depositional area. With the obtained environmental LAS concentrations, a risk assessment for this surfactant has been carried out, based on publicly available acute and chronic toxicity data in target organisms. The results indicated that LAS could pose a low risk for the existing benthic community applying worst case scenario assessment. This is the first time that levels of LAS have been measured in environmental samples of the southern Baltic Sea.

LAS degradability by marine biofilms derived from seawater in Spain and Sweden

Marine biofilms were established on glass beads with or without deliberate pre-exposure to LAS (20 μg/L) in Spain (Cadiz) and Sweden (Kristineberg). The ability of each community to mineralize LAS (100 μg/L) was then assessed in biometers at four experimental temperatures (between 6 and 21°C). Genetic diversity and biomass of the biofilms were assessed by genetic fingerprinting (DGGE) and direct bacterial counts. With biofilms from Sweden, where LAS was not detected in seawater (n = 3), deliberate pre-exposure to LAS resulted in lower genetic diversity and higher mineralization rate constant; however, with biofilms from Spain, where 6.4 ± 3.9 μgLAS/L (n = 3) was measured during the colonization, pre-exposure did not affect the bacterial community. Bacterial acclimation therefore appeared to have been induced at environmental concentrations < 6 μgLAS/L. Environmental pre-exposure was not a pre-requisite for featuring the full consortia of LAS degraders in the biometers. The mineralization rate was described using an Arrhenius equation at experimental temperatures within the typical annual range; however, they departed from this model below this range.

Sorption-desorption kinetics and toxic cell concentration in marine phytoplankton microalgae exposed to Linear Alkylbenzene Sulfonate

Linear Alkylbenzene Sulfonates (LAS) are ubiquitous surfactants. Traces can be found in coastal environments. Sorption and toxicity of C(12)-LAS congeners were studied in controlled conditions (2-3500 μg C(12)LAS/L) in five marine phytoplanktonic species, using standardized methods. IC(50) values ranged from 0.5 to 2 mg LAS/L. Sorption of (14)C(12)-6 LAS isomer was measured at environmentally relevant trace levels (4μg/L) using liquid scintillation counting. Steady-state sorption on algae was reached within 5h in the order dinoflagellate>diatoms>green algae. The sorption data, fitted a L-type Freundlich isotherm, indicating saturation. Desorption was rapid but a low LAS fraction was still sorbed after 24h. Toxic cell concentration was 0.38±0.09 mg/g for the studied species. LAS toxicity results from sorption on biological membranes leading to non-specific disturbance of algal growth. Results indicate that LAS concentrations in coastal environments do not represent a risk for these organisms.

Growth and antioxidant response in Hydrocharis dubis (Bl.) Backer exposed to linear alkylbenzene sulfonate

A two-week exposure experiment was designed to investigate the toxicity of linear alkylbenzene sulfonate (LAS) on the aquatic plant Hydrocharis dubis (Bl.) Backer, focusing on growth, photosynthetic pigments and the activities of antioxidant enzymes. No significant differences were observed in the growth parameters of H. dubis when H. dubis was exposed to lower LAS doses (<or=10 mg l(-1)). However, lower LAS doses remarkably promote the dry weight accumulation of H. dubis. Higher doses of LAS (>10 mg l(-1)) resulted in significant decreases in all growth parameters of H. dubis. No significant effect on pigment contents was observed at up to 50 mg l(-1) LAS, beyond which pigment contents declined gradually. Malondialdehyde (MDA) content did not show obvious differences when H. dubis plants were exposed to <or=50 mg l(-1) LAS. Peroxidase (POD), superoxide dismutase (SOD) and catalase (CAT) activities showed a concentration-dependent increase up to LAS concentrations of 0.1-10 mg l(-1), followed by a clear decrease. The results of this study suggest that LAS significantly inhibited the growth and physiology of H. dubis when the dose of LAS exceeded 10 mg l(-1) . Therefore, LAS at current environmental concentrations dose not appear to cause evident phytotoxic effects on H. dubis.

Suitability of the marine prosobranch snail Hydrobia ulvae for sediment toxicity assessment: A case study with the anionic surfactant linear alkylbenzene sulphonate (LAS)

Individuals of the mudsnail Hydrobia ulvae (Pennant) (Mollusca: Prosobranchia) were exposed to sediments spiked with increasing concentrations (1.59-123.13mgkg(-1) dry weight) of the anionic surfactant linear alkylbenzene sulphonate (LAS) which is employed in the formulation of laundry powders and liquids, as well as hand dishwashing products. The suitability of the selected organism, H. ulvae for routine sediment toxicity testing was evaluated by measuring acute toxicity recording survival. Sublethal toxicity was evaluated as total number of produced veliger larvae per treatment throughout the test (9d). Mortality has shown to be a reliable and reproducible indicator of acute toxicity. LC(50) values were comprised between 203.4 (48h) and 94.3mgkg(-1) (9d) dry weight. As sublethal endpoint, the total number of produced larvae showed to be a useful indicator of toxicity for this organism. The number of produced larvae increased at lower exposure concentrations, whereas at the highest LAS concentration, the number of produced larvae decreased. This is the first report of acute and sublethal toxicity of sediment associated LAS for this species.

Effect of sediment properties on the sorption of C12-2-LAS in marine and estuarine sediments

Linear alkylbenzene sulfonates (LAS) are anionic high production volume surfactants used in the manufacture of cleaning products. Here, we have studied the effect of the characteristics of marine and estuarine sediments on the sorption of LAS. Sorption experiments were performed with single sediment materials (pure clays and sea sand), with sediments treated to reduce their organic carbon content, and with field marine and estuarine sediments. C12-2-LAS was used as a model compound. Sorption to the clays montmorillonite and kaolinite resulted in non-linear isotherms very similar for both clays. When reducing the organic content, sorption coefficients decreased proportionally to the fraction removed in fine grain sediments but this was not the case for the sandy sediment. The correlation of the sediment characteristics with the sorption coefficients at different surfactant concentrations showed that at concentrations below 10 microg C12-2-LAS/L, the clay content correlated better with sorption, while the organic fraction became more significant at higher concentrations.

Occurrence of anionic surfactants in treated sewage: risk assessment to aquatic environment

A comparative evaluation of occurrence of and risk to aquatic environment due to anionic surfactants (AS) in treated effluents from three main treatment processes, i.e. activated sludge process (ASP), oxidation pond (OP), and upflow anaerobic sludge blanket reactor (UASBR) is presented. UASBR effluents contained substantial concentrations of AS (4.25-5.91mg/L as average AS removal was not found to exceed 18%). Post-treatment of UASBR effluent using 1-1.6 days detention, anaerobic polishing ponds (PP) was also found quite ineffective. In UASBR-PP combine, AS reduced only up to 30%. Effluents from OP based sewage treatment plants (STPs) also contained significant concentrations of AS. On the contrary, effluent AS or linear alkylbenzene sulfonate (LAS) concentrations recorded in ASP effluents were quite low (less than 0.2mg/L). Unlike UASBR, LAS or AS removals greater than 99% are achieved in ASP. Treated effluents from UASBR and OP based STPs when discharged to aquatic ecosystems are likely to cause substantial risk to aquatic environment due to the presence of AS while effluents from ASP are not supposed to pose risk. Need to find an effective aerobic post-treatment unit to UASBR for desired removal of AS is emphasized.

Ecotoxicity and biodegradability of an alkyl ethoxysulphate surfactant in coastal waters

Alkyl ethoxysulphates (AES) are anionic surfactants widely used in numerous commercial and industrial applications. In spite of the high AES volume consumption a few data concerning the occurrence, fate and effects of AES in marine environments are reported in literature. The objective of this study is to evaluate the biodegradability and toxicity of AES in pristine sea water. Ultimate biodegradation was studied according to the guideline 835.3160 "Biodegradability in sea water" proposed by the United States Environmental Protection Agency (USEPA). Acute toxicity of AES was studied to the microalgae Nannochloropsis gaditana, Isochrysis galbana, Chaetoceros gracilis, Dunaliella salina and Tetraselmis chuii and the invertebrate Artemia franciscana, using culture growth inhibition and death, respectively, as effect criteria. During the degradative process two different stages were observed, which were better described with the first order and logistic kinetic models, respectively. Lag times were 3.3 (stage A) and 26.5 (stage B) days whereas half-lives were 18.6 (stage A) and 49.8 (stage B) days. AES inhibited the microalgae growth, with 96-h EC50 values ranging from 4.68 g L(-1) for D. salina to 24.02 mg L(-1) for I. galbana. Mean 48- and 72-h LC50 values for A. franciscana were 38.30 and 23.92 mg L(-1), respectively. The results indicate an extensive biodegradability of AES in sea water, although at a very slow rate. Acute toxicity was highly dependent on the species tested, being the green alga D. salina the most affected organism. The present study provides relevant data concerning the biodegradability and adverse effects of an AES surfactant on marine organisms, which are useful to establish water quality criteria in a regulatory framework.

Inhibition of growth and photosynthesis of selected green microalgae as tools to evaluate toxicity of dodecylethyldimethyl-ammonium bromide

The effect of dodecylethyldimethyl-ammonium bromide (DEAB), a quaternary ammonium, compound widely used as disinfectant, on phytoplankton of inland water systems was analysed by using an experimental model. A toxicity test was based on inhibition of photosynthesis performances (effective quantum yield from photosystem II, Phi(PSII) and O(2) production) of the phytoplanktonic species Scenedesmus intermedius and Dictiosphaerium chlorelloides (Chlorophyceae) under growing doses of DEAB. A concentration-dependent toxic response was obtained in both parameters analysed. In addition, this response was almost immediate. Consequently, the measurement of both parameters (Phi(PSII )and O(2) production) allows to assess DEAB toxicity with higher standards of precision and repeatability. We propose that this procedure could be used to detect presence of quaternary ammonium pollutants in freshwater.

Derivation of predicted no effect concentrations (PNEC) for marine environmental risk assessment: application of different approaches to the model contaminant Linear Alkylbenzene Sulphonates (LAS) in a site-specific environment

Four sediment-dwelling marine organisms were exposed to sediments spiked with increasing concentrations of Linear Alkylbenzene Sulphonate (LAS). The selected endpoint mortality was reported daily and acute LC(50) (96 h), as well as final LC(10) values were calculated for the derivation of environmentally safe predicted no effect concentrations (PNEC) for the sediment compartment. PNECs were estimated by both application of assessment factors (AF) and the equilibrium partitioning method (EPM) as proposed by the EU TGD. Finally, environmental risk assessment in a site-specific environment, the Sancti Petri Channel, South Iberian Peninsula, was carried out at three different sampling stations with known environmental LAS concentrations. PNECs obtained by the assessment factor approach with acute toxicity data were one to two orders of magnitude lower than those from the equilibrium partitioning method. On the other hand, when applying lower AFs to the estimated LC(10) values, the PNECs obtained by both approaches were more similar. Environmental risk assessment carried out with the estimated PNECs in a site specific environment with known sediment LAS concentrations revealed that PNECs obtained with acute toxicity data were over conservative whereas those obtained with AF=10 on LC(10) data and EPM produced more realistic results in accordance with field observations carried out in the study area.

Interspecies correlation estimates predict protective environmental concentrations

Environmental risk assessments often use multiple single species toxicity test results and species sensitivity distributions (SSDs) to derive a predicted no-effect concentration in the environment, typically the 5th percentile of the SSD, termed the HC5. The shape and location of the distribution are best known when populated with numerous toxicity values. To help overcome the cost of multiple toxicity tests, we explored the potential of the U.S. EPA's Interspecies Correlation Estimation (ICE) program to predict single species toxicity values from a single known toxicity value. ICE uses the initial toxicity estimate for one species to produce correlation toxicity values for multiple species, which can be used to develop SSD and HC5. To test this approach to deriving HC5, we generated toxicity values based on measured toxicity values for three surrogate species Pimephales promelas (Fathead minnow), Onchorynchus mykiss (Rainbow trout), and Daphnia magna (water flea). Algal taxa were not used due to the paucity of high quality algal-aquatic invertebrate and algal-fish correlations. The compounds used (dodecyl linear alkylbenzenesulfonate (LAS), nonylphenol, fenvalerate, atrazine, and copper) have multiple measured toxicity values and diverse modes of action and toxicities. Distribution parameters and HC5 values from the measured toxicity values were compared with ICE predicted distributions and HC5 values. While distributional parameters (scale and intercept) differed between measured and predicted distributions, in general, the ICE-based SSDs had HC5 values that were within an order of magnitude of the measured HC5 values. Examination of species placements within the SSDs indicated that the most sensitive species were coldwater species (e.g., salmonids and Gammarus pseudolimnaeus). These results raise the potential of using quantitative structure activity models to estimate HC5s.

Fate, behavior and effects of surfactants and their degradation products in the environment

Surfactants are widely used in household and industrial products. After use, surfactants as well as their products are mainly discharged into sewage treatment plants and then dispersed into the environment through effluent discharge into surface waters and sludge disposal on lands. Surfactants have different behavior and fate in the environment. Nonionic and cationic surfactants had much higher sorption on soil and sediment than anionic surfactants such as LAS. Most surfactants can be degraded by microbes in the environment although some surfactants such as LAS and DTDMAC as well as alkylphenols may be persistent under anaerobic conditions. LAS were found to degrade in sludge amended soils with a half-lives of 7 to 33 days. Most surfactants are not acutely toxic to organisms at environmental concentrations and aquatic chronic toxicity of surfactants occurred at concentrations usually greater than 0.1 mg/L. However, alkylphenols have shown to be capable of inducing the production of vitellogenin in male fish at a concentration as low as 5 microg/L. More toxicity data are needed to assess the effects on terrestrial organisms such as plants.

Effects of a surfactant (FFD-6) on Scenedesmus morphology and growth under different nutrient conditions

Surfactants are man-made compounds that are meanwhile omnipresent in the environment, but environmental concentrations of surfactants are such that they are thought to have little risk for aquatic systems. The major anionic surfactants currently on the global market are linear alkylbenzene sulfonates (LAS), a class where the commercially available FFD-6 belongs to. The hypothesis was tested that sublethal effects of FFD-6, i.e. the morphological effect of colony formation in the common test alga Scenedesmus obliquus, occurs at a concentration lower than the no-observed-effect concentrations for endpoints commonly used in regulatory toxicity testing with algae. The surfactant FFD-6 induced colonies in Scenedesmus at concentrations a few orders of magnitude lower (i.e. between 0.001 and 0.01 g l-1) than at which growth inhibition was observed (i.e. between 1 and 10g l -1). Growth rates were lowest for Scenedesmus grown in P-limited medium, intermediate for algae reared in N-limited medium and highest for algae cultured in non-limited standard medium. Growth inhibition due to FFD-6 was similar for non-limited and nutrient-limited Scenedesmus, but colony formation was stronger in non-limited Scenedesmus than in nutrient limited cultures. The colony inducing effect of the surfactant FFD-6 on Scenedesmus occurs at much lower concentrations than growth inhibition and might affect species interactions, the survival of species and the energy flow along the food chain.