Plastics are cheap, strong, and durable and offer considerable benefits to humanity. They potentially can enhance the benefits that both medical and scientific technology will bestow to humankind. However, it has now been several decades since the use of plastics exploded, and we have evidence that our current approach to production, use, transport and disposal of plastic materials has caused, and is still causing serious effects on wildlife, and is not sustainable. Because of frequent inappropriate waste management practices, or irresponsible human behavior, large masses of plastic items have been released into the environment, and thereby have entered the world's oceans. Moreover, this process continues, and in some places is even increasing. Most plastic debris that now exists in the marine environment originated from ocean-based sources such as the fishing industry. Plastics accumulate in coastal areas, at the ocean surface and on the seabed. Because 70% of all plastics are known to eventually sink, it is suspected that ever increasing amounts of plastic items are accumulating in seabed sediments. Plastics do not biodegrade, although, under the influence of solar UV radiations, plastics do degrade and fragment into small particles, termed microplastics. Our oceans eventually serve as a sink for these small plastic particles and in one estimate, it is thought that 200,000 microplastics per km(2) of the ocean's surface commonly exist. The impact of plastic debris has been studied since the beginning of the 1960's. To date, more than 267 species in the marine environment are known to have been affected by plastic entanglement or ingestion. Marine mammals are among those species that are most affected by entanglement in plastic debris. By contrast, marine birds suffer the most from ingestion of plastics. Organisms can also be seriously absorbed by floating plastic debris, or the contaminants may derive from plastic additives that are leached to the environment. Recent studies emphasize the important role of microplastics as they are easily ingestible by small organisms, such as plankton species, and form a pathway for contaminants to enter the food web. Contaminants leached from plastics tend to bioaccumulate in those organisms that absorb them, and chemical concentrations are often higher at higher trophic levels. This causes a threat to the basis of every food web and can have serious and far-reaching effects, even on nonmarine species such as polar bears and humans, who consume marine-grown food. Therefore, resolving the plastic debris problem is important to human kind for two reasons: we are both creator, and victim of the plastic pollution problem. Solutions to the plastic debris problem can only be achieved through a combination of actions. Such actions include the following: Legislation against marine pollution by plastics must be enforced, recycling must be accentuated, alternatives (biodegradable) to current plastic products must be found, and clean-up of debris must proceed, if the marine plastic pollu...
Protecting Arctic ecosystems against potential adverse effects from anthropogenic activities is recognized as a top priority. In particular, understanding the accumulation and effects of persistent organic pollutants (POPs) in these otherwise pristine ecosystems remains a scientific challenge. Here, we combine more than 20,000 tissue concentrations, a food web bioaccumulation model, and time trend analyses to demonstrate that the concentrations of legacy-POPs in the Barents/Norwegian Sea fauna decreased 10-fold between 1985 and 2010, which reflects regulatory efforts to restrict these substances. In contrast, concentrations of fossil fuel derived PAHs in lower trophic levels (invertebrates and fish) increased 10 to 30 fold over the past 25 years and now dominate the summed POP burden (25 POPs, including 11 PAHs) in these biota. Before 2000, PCBs dominated the summed POP burden in top predators. Our findings indicate that the debate on the environmental impacts of fossil fuel burning should move beyond the expected seawater temperature increase and examine the possible environmental impact of fossil fuel derived PAHs.
Per-and polyfluoroalkyl substances (PFAS) form weak van der Waals (vdW) interactions, which render this class of chemicals more volatile than nonfluorinated analogues. Here, the hexadecane/air partition coefficient (K Hxd/air ) values at 25 °C, as an index of vdW interaction strength and volatility, were determined for 64 neutral PFAS using the variable phase ratio headspace and gas chromatographic retention methods. Log K Hxd/air values increased linearly with increasing number of CF 2 units, and the increase in log K Hxd/air value per CF 2 was smaller than that per CH 2 . Comparison of PFAS sharing the same perfluoroalkyl chain length but with different functional groups demonstrated that K Hxd/air was highest for the N-alkyl perfluoroalkanesulfonamidethanols and lowest for the perfluoroalkanes and that the size of the nonfluorinated structure determines the difference in K Hxd/air between PFAS groups. Two models, the quantum chemistry-based COSMOtherm model and an iterative fragment selection quantitative structure− property relationship (IFS-QSPR) model, accurately predicted the log K Hxd/air values of the PFAS with root-mean-square errors of 0.55 and 0.35, respectively. COSMOtherm showed minor systematic errors for all PFAS, whereas IFS-QSPR exhibited large errors for a few PFAS groups that were outside the model applicability domain. The present data set will be useful as a benchmark of the volatilities of the various PFAS and for predicting other partition coefficient values of PFAS.
Chlorinated paraffins (CPs) are highly complex mixtures of polychlorinated <i>n</i>-alkanes with differing chain lengths and chlorination patterns. Knowledge on physicochemical properties of individual congeners is limited but needed to understand their environmental fate and potential risks. This work combines a sophisticated but time-demanding quantum chemically based method COSMO-RS and a fast-running fragment contribution approach to establish models to predict partition coefficients of a large number of short-chain chlorinated paraffin (SCCP) congeners. Molecular fragments of a length of up to C<sub>4</sub> in CP molecules were counted and used as explanatory variables to develop linear regression models for predicting COSMO-RS-calculated values. The resulting models can quickly provide COSMO-RS predictions for octanol–water (<i>K</i><sub>ow</sub>), air–water (<i>K</i><sub>aw</sub>), and octanol–air (<i>K</i><sub>oa</sub>) partition coefficients of SCCP congeners with an accuracy of 0.1–0.3 log units root mean squared errors (RMSE). The model predictions for <i>K</i><sub>ow</sub> agree with experimental values for individual constitutional isomers within 1 log unit. The ranges of partition coefficients for each SCCP congener group were computed, which successfully reproduced experimental log <i>K</i><sub>ow</sub> ranges of industrial CP mixtures. As an application of the developed approach, the predicted <i>K</i><sub>aw</sub> and <i>K</i><sub>oa</sub> were plotted to evaluate the bioaccumulation potential of each SCCP congener group.
Octanol-water partitioning (Kow) is considered a key parameter for hydrophobicity and is often applied in the prediction of the environmental fate and exposure of neutral organic compounds. However, surfactants can create difficulties in the determination of Kow because of emulsification of both water and octanol phases. Moreover, not only is sorption behavior of ionic surfactants related to hydrophobicity, but also other interactions are relevant in sorption processes. A different approach to develop parameters that can be applied in predictive modeling of the fate of surfactants in the environment is therefore required. Distribution between solid-phase microextraction (SPME) fibers and water was used in this study to measure the affinity of surfactants to a hydrophobic phase. Fiber-water sorption coefficients of alcohol ethoxylates, alkyl carboxylates, alkyl sulfates, and alkyl sulfonates were determined at pH 7 by equilibration of the test analytes between fiber and water. Distribution between fiber and water of anionic compounds with pKa ∼ 5 (i.e., alkyl carboxylates) was dominated by the neutral fraction. Anionic surfactants with pKa ≤ 2 (i.e., alkyl sulfates and alkyl sulfonates) showed strong nonlinear distribution to the fiber. The fiber-water sorption coefficients for alcohol ethoxylates and alkyl sulfates showed a linear trend with bioconcentration factors from the literature. Fiber-water sorption coefficients are promising as a parameter to study the effects of hydrophobicity and other potential interactions on sorption behavior of neutral and anionic surfactants.
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