R.W.P.M. Laane

Environmental and Toxicity Effects of Perfluoroalkylated Substances

The production, use, environmental fate, occurrence, and toxicity of perfluoroalkylated substances have been reviewed. Although only a limited number of essential physicochemical data are available, thus hampering a complete assessment of the environmental fate of PFAS, it has become clear that PFAS behave differently from other nonpolar organic micropollutants. PFAS are present in environmental media in urbanized areas both with and without fluorochemicals production sites. The presence of PFOS at levels above the limit of detection has been demonstrated in almost all organisms sampled in a global survey as well as in both nonexposed and exposed human populations. The acute and chronic ecotoxicity of PFOS, PFOA, and 8:2 FTOH to aquatic organisms is moderate to low. Acute toxicity to rodents is also low. PFOS concentrations in effluents have been reported that approach indicative target values derived from available aquatic toxicity data. PFOA has been found to be weakly carcinogenic. This review shows the importance of the perfluoroalkylated substances for the environment and the necessity to fill the current gaps in knowledge of their environmental fate and effects.

Transportation of water, particulate and dissolved organic and inorganic matter between a salt marsh and the Ems-Dollard estuary, The Netherlands

Abstract Transport processes were studied in a gully between a salt marsh and an estuary. After storm tides, ebb currents in the gully reached high values. It is concluded that particulate matter (both organic and inorganic) are imported into the marsh. Coarse organic debris is exported during storm tides, but this amount is low when compared with the primary production on the marsh. Exports are shown for dissolved organic carbon, ammonia, phosphate and silica, while nitrate and possibly nitrite are imported. Organic matter derived from in situ production and net import is buried and partly mineralized in the marsh.

Modeling aggregation and sedimentation of nanoparticles in the aquatic environment

With nanoparticles being used more and more in consumer and industrial products it is almost inevitable that they will be released into the aquatic environment. In order to understand the possible environmental risks it is important to understand their behavior in the aquatic environment. From laboratory studies it is known that nanoparticles in the aquatic environment are subjected to a variety of processes: homoaggregation, heteroaggregation to suspended particulate matter and subsequent sedimentation, dissolution and chemical transformation. This article presents a mathematical model that describes these processes and their relative contribution to the behavior of nanoparticles in the aquatic environment. After calibrating the model with existing data, it is able to adequately describe the published experimental data with a single set of parameters, covering a wide range of initial concentrations. The model shows that at the concentrations used in the laboratory, homoaggregation and sedimentation of the aggregates are the most important processes. As for the natural environment much lower concentrations are expected, heteroaggregation will play the most important role instead. More experimental datasets are required to determine if the process parameters that were found here are generally applicable. Nonetheless it is a promising tool for modeling the transport and fate of nanoparticles in watersheds and other natural water bodies.

Smartbuoy: A marine environmental monitoring buoy with a difference

Abstract High frequency measurements of physical, chemical and biological variables are being routinely made employing a moored platform (SmartBuoy) in UK shelf-seas. The rationale for the design and configuration of SmartBuoy are described together with details of the system control, software environment and telemetry capability. An 18- month time series of results, showing different scales of variability from annual, through seasonal to daily of a range of measured variables, is presented. Future developments to extend the capability of the current version of SmartBuoy to measure wave direction and current speed are described together with a description of the next generation SmartBuoy 3 platform.

Dancing with the Tides: Fluctuations of Coastal Phytoplankton Orchestrated by Different Oscillatory Modes of the Tidal Cycle

Population fluctuations are often driven by an interplay between intrinsic population processes and extrinsic environmental forcing. To investigate this interplay, we analyzed fluctuations in coastal phytoplankton concentration in relation to the tidal cycle. Time series of chlorophyll fluorescence, suspended particulate matter (SPM), salinity and temperature were obtained from an automated measuring platform in the southern North Sea, covering 9 years of data at a resolution of 12 to 30 minutes. Wavelet analysis showed that chlorophyll fluctuations were dominated by periodicities of 6 hours 12 min, 12 hours 25 min, 24 hours and 15 days, which correspond to the typical periodicities of tidal current speeds, the semidiurnal tidal cycle, the day-night cycle, and the spring-neap tidal cycle, respectively. During most of the year, chlorophyll and SPM fluctuated in phase with tidal current speed, indicative of alternating periods of sinking and vertical mixing of algal cells and SPM driven by the tidal cycle. Spring blooms slowly built up over several spring-neap tidal cycles, and subsequently expanded in late spring when a strong decline of the SPM concentration during neap tide enabled a temporary “escape” of the chlorophyll concentration from the tidal mixing regime. Our results demonstrate that the tidal cycle is a major determinant of phytoplankton fluctuations at several different time scales. These findings imply that high-resolution monitoring programs are essential to capture the natural variability of phytoplankton in coastal waters.

Assessment of azaarenes and azaarones (oxidized azaarene derivatives) in the Dutch coastal zone of the North Sea

Azaarones (oxidized derivatives of azaarenes) is a group of newly emerging chemical compounds. Little is known about their occurrence in the aquatic environment. Azaarenes are polycyclic aromatic heterocyclic compounds containing one nitrogen atom in one of the aromatic rings. The (photo) oxidized metabolites of the azaarenes are often more toxic than the parent compound. For the first time the concentration of seven azaarenes and seven primary metabolites have been measured in the surface sediments (fraction<63microm) of the Dutch coastal zone of the North Sea. Samples collected in 2000 and 2001 were analyzed using a newly developed method to determine the contents of azaarenes and azaarones simultaneously in a single GC-MS run. The concentrations of acridine, benz[a]acridine, benz[c]acridine and 5,6-benzoquinoline varied between 10-63, 3.9-25, 3.3-11 and 3.98-10.84ngg(-1), respectively. Concentrations of 7,8-benzoquinoline and phenanthridine were below the limit of detection. 2-Hydroxyquinoline and 5-hydroxyquinoline, probably metabolites of quinoline, were present in relatively high concentrations: 7.4-949 and 11-188ngg(-1). A gradient was observed with highest concentrations of the sum of azaarenes and the sum of the concentration of their metabolites close to the coast and lower concentrations further offshore. The concentrations of azaarenes and their metabolites are in the same order of magnitude as those found to induce phototoxicity to algae. The concentrations of mineral oil and PAHs in the surface sediments of the Dutch coastal zone of the North Sea were, at most locations, above the Dutch chemical targets for environmental protection. Spatial distribution of PAHs and mineral oil were slightly different from those of azaarenes and transformation products. Simultaneous GC-MS for azaarenes and their degradation products is possible but extraction/clean up can be further improved. Azaarenes as well as their primary metabolic products are present in the marine environment. In sediments the cumulative concentrations of transformation products amount to about four times the cumulative concentrations of the azaarenes. In conclusion, azaarenes and their metabolites constitute a new group of emerging polycyclic aromatic compounds which need more attention in the future.

Predicting the contribution of nanoparticles (Zn, Ti, Ag) to the annual metal load in the Dutch reaches of the Rhine and Meuse

Although nanoparticles are being increasingly used in consumer products, the risks they may pose to the environment and to human health remain largely unknown. One important reason for this is the lack of quantitative techniques for identifying and measuring the amount of nanomaterials in environmentally relevant circumstances. Such techniques should also discriminate between manufactured and naturally occurring nanoparticles, so that the influence of human activities can be identified. This article describes a technique for estimating nanoparticles by calculating the potential releases of nano-forms of zinc, titanium and silver, the three metals that are widely used for nano-enhanced products, and comparing them to the total loads, based on measurements of the total concentration. We use The Netherlands for our case study. Combining the scarce available data (indicative figures on the content of nanomaterials in various products and usage profiles found in an unrelated category of research) we were able to estimate the total use of such materials in The Netherlands and therefore the potential release into the environment. The calculations indicate that nanomaterials contribute a small but discernible fraction (5 to 20%) to the total loads of zinc and titanium in the Dutch reaches of the Rhine and Meuse. For silver the contribution is at most 3%. The contribution is, however, close to the minimum that can be detected, given the variability in the measured concentrations.

Modelling the Release, Transport and Fate of Engineered Nanoparticles in the Aquatic Environment - A Review.

Engineered nanoparticles, that is, particles of up to 100 nm in at least one dimension, are used in many consumer products. Their release into the environment as a consequence of their production and use has raised concern about the possible consequences. While they are made of ordinary substances, their size gives them properties that are not manifest in larger particles. It is precisely these properties that make them useful. For instance titanium dioxide nanoparticles are used in transparent sunscreens, because they are large enough to scatter ultraviolet light but too small to scatter visible light.To investigate the occurrence of nanoparticles in the environment we require practical methods to detect their presence and to measure the concentrations as well as adequate modelling techniques. Modelling provides both a complement to the available detection and measurement methods and the means to understand and predict the release, transport and fate of nanoparticles. Many different modelling approaches have been developed, but it is not always clear for what questions regarding nanoparticles in the environment these approaches can be applied. No modelling technique can be used for every possible aspect of the release of nanoparticles into the environment. Hence it is important to understand which technique to apply in what situation. This article provides an overview of the techniques involved with their strengths and weaknesses. Two points need to be stressed here: the modelling of processes like dissolution and the surface activity of nanoparticles, possibly under influence of ultraviolet light, or chemical transformation has so far received relatively little attention. But also the uncertainties surrounding nanoparticles in general-the amount of nanoparticles used in consumer products, what constitutes the appropriate measure of concentration (mass or numbers) and what processes are relevant-should be explicitly considered as part of the modelling.

Determination of metal-based nanoparticles in the river Dommel in the Netherlands via ultrafiltration, HR-ICP-MS and SEM

We investigated the occurrence of metal-based nanoparticles in a natural system, the river Dommel in the Netherlands. The river itself is well-studied as far as hydrology and water quality is concerned, easily accessible and contains one major wastewater treatment plant discharging onto this river. We sampled water from various locations along the river and collected samples of influent, effluent and sewage sludge from the wastewater treatment plant. The sampling campaign was carried out in June 2015 and these samples were analysed for seven elements using high-resolution inductively coupled plasma mass spectrometry (HR-ICP-MS), ultrafiltration with a sequence of mesh sizes and scanning electron microscopy (SEM). From the results we conclude that there are indeed nanoparticles present in the treatment plant we studied, as we found titanium and gold particles in the influent and effluent. In the river water only 10 to 20% of the mass concentration of titanium, cerium and other elements we examined is made up of free, i.e. unattached, particles with a size smaller than 20 nm or of dissolved material. The rest is attached to natural colloids or is present as individual particles or clusters of smaller particles, as it could be filtered out with 450 nm ultrafilters. We found evidence that there is no appreciable anthropogenic emission of cerium into the river, based on the geochemical relationship between cerium and lanthanum. Besides, the effluent of the treatment plant has lower concentrations of some examined elements than the surface water upstream. The treatment plant discharges much less of these elements than estimated using previous publications. However, a potential diffuse source of titanium dioxide in the form of nanoparticles or of larger particles is their use in paints and coatings, as the concentration of titanium increased considerably in the urbanised area of the river Dommel.

Modeling organic compounds in the estuarine and coastal environment

This chapter describes the historical development and present applications of water-quality models for organic chemical compounds (e.g., polychlorinated biphenyls (PCBs) and polycyclic aromatic hydrocarbons (PAHs)). Various types of water-quality models are described, varying in the amount of compartments, in spatial dimension, and in time. Special attention is given to the processes acting on these chemical compounds (e.g., volatilization and decomposition) and to the quality and precision of the value of parameters in these processes. An overview is given of the most important water-quality models in use now. The chapter concludes with attention and discussion points on accuracy and precision of model predictions and how to use these models for hazard and risk assessment. At the end, recommendations are presented for improving the further development and application of water-quality models by benchmarking and monitoring.