Emerging pollutants in the environment:A challenge for water resource management

A significant number of emerging pollutants(EPs)resulting from point and diffuse pollution is present in the aquatic environment.These are chemicals that are not commonly monitored but have the potential to enter the environment and cause adverse ecological and human health effects.According to the NORMAN network,at least 700 substances categorized into 20 classes,have been identified in the European aquatic environment.In light of their potential impact action is urgently required.In this study,we present a concept that shows the current state of art and challenges for monitoring programs,fate and risk assessment tools and requirements for policies with respect to emerging pollutants as a base for sustainable water resource management.Currently,methods for sampling and analysis are not harmonized,being typically focused on certain EP classes.For a number of known highly hazardous EPs detection limits are too high to allow proper risk assessment.For other EPs such as microplastics method development is in its infancy.Advanced ultra-sensitive instrumental techniques should be used for quantitative determination of prioritized EPs in water,suspended matter,soil and biota.Data on EPs'and their metabolites'properties that determine their fate in the environment are often not available.National surveys on water quality often use different parameters for water quality assessment and often do not include EPs.A harmonized monitoring of surface and groundwater is not yet achieved and urgently required.Specific component integrated into models assessing the fate of EPs in a multi compartment environmental approach are missing and must be developed.The main goal of risk assessment is the overall protection of ecological communities in the aquatic environment and human health.New methods for assessing the cumulative risks from combined exposures to several stressors,including mixtures of EPs in a multi-scale approach are required.A combination of regulations and management measures with respect to use/emissions of EPs into the environment,as well as to their occurrence in the environment are fundamental to reach an efficient water resource management.

Influences of perfluorooctanoic acid on the aggregation of multi-walled carbon nanotubes

The aggregation of multi-walled carbon nanotubes （MWCNTs） in the aqueous phase not only inhibits their extensive utilization in various aspects but also dominates their environmental fate and transport.The role of surfactants at low concentration in the aggregation of MWCNTs has been studied,however the effect of perfluorinated surfactants at low concentration is uncertain.To understand this interfacial phenomenon,the influences of perfluorooctanoic acid （PFOA）,and sodium dodecyl sulfate （SDS） as a control,on MWCNT aggregation in the aqueous phase were examined by the UV absorbency method.Influences of pH and cationic species on the critical coagulation concentration （CCC） value were evaluated.The CCC values were dependent on the concentration of PFOA,however a pronounced effect of SDS concentration on the CCC values was not observed.The CCC values of the MWCNTs were 51.6 mmol/L in NaCl and 0.28 mmol/L in CaCl 2 solutions,which suggested pronounced differences in the effects of Na＋ and Ca2＋ ions on the aggregation of the MWCNTs.The presence of both PFOA and SDS significantly decreased the CCC values of the MWCNTs in NaCl solution.The aggregation of the MWCNTs took place under acidic conditions and was not notably altered under neutral and alkaline conditions due to the electrostatic repulsion of deprotonated functional groups on the surface of the MWCNTs.