Characterization, chemodynamics and environmental impact assessment of leachates from complex organic materials

More than 65,000 organic chemicals are currently in commercial production with approximately 1000 added each year. Many chemicals are released into the environment as organic mixtures derived from complex hazardous or solid wastes. Of these, more than 1000 chemicals are of environmental concern because of their production quantities, toxicity, persistence, and tendency to bioaccumulate. To manage the impacts of these chemicals to the environment, the environmental chemodynamics of such Complex Organic Mixtures (COMs) or Solid Waste Materials (SWMs) must be predicted accurately. Required information includes the molecular organic composition of SWMs/COMs and/or their leachates, the transport processes and migration in and between the various multimedia environments, chemical and biochemical transformation processes, and effects on the interacting organisms. A technique is developed to predict the potential impact of SWMs/COMs based on the organic chemical composition of the extracts from such complex materials and/or their leachates. In addition, the methodology can be used to estimate the potential hazards of organic pollutants in such complex mixture, ultimate fate and environmental toxicity. This technique consists of three fundamental approaches: characterization and source partitioning, chemodynamics and Environmental Impact Assessment (EIA) models. The characterization and source partitioning model of SWMs/COMs and their leachates are based on their lipid molecular marker (MM) signatures. Chemodynamics (i.e., Fate-Transport) model is based on experiments such as leaching, sorption, volatilization, photolysis, and biodegradation. These experiments are carried out for different SWM leachates and a group of polycyclic aromatic hydrocarbons (PAHs) that are characteristic to the studied leachates. The Environmental Impact Assessment (EIA) model estimates the probability of 96-hr fresh water alga Selenastrum capricornutum chronic toxicity of EPAH-containing SWMs/COMs using a combination of leaching kinetics, equilibrium partitioning, QSPR-QSAR, toxic unit, multicomponent joint toxic effect of mixtures (i.e., additivity, synergism, or antagonism) and dose-response models. The EPAH model is verified by comparing both predicted and observed toxicity in different waste materials. Molecular Connectivity-Quantitative Structure Activity Relationship (MC-QSAR) techniques then are used to develop a predictive model to estimate the concentrations of PAH components in mixtures derived from SWMs/COMs leachates that would jointly cause 50% inhibition of alga Selenastrum capricornutum toxicity.Keywords: Environmental Chemo dynamics, Environmental Pollution, Leschates, Characterization of organic compounds, Environmental Impact Assessmen

Discerning natural and anthropogenic organic matter inputs to salt marsh sediments of Ria Formosa lagoon (South Portugal)

Sedimentary organic matter (OM) origin and molecular composition provide useful information to understand carbon cycling in coastal wetlands. Core sediments from threors' Contributionse transects along Ria Formosa lagoon intertidal zone were analysed using analytical pyrolysis (Py-GC/MS) to determine composition, distribution and origin of sedimentary OM. The distribution of alkyl compounds (alkanes, alkanoic acids and alkan-2-ones), polycyclic aromatic hydrocarbons (PAHs), lignin-derived methoxyphenols, linear alkylbenzenes (LABs), steranes and hopanes indicated OM inputs to the intertidal environment from natural-autochthonous and allochthonous-as well as anthropogenic. Several n-alkane geochemical indices used to assess the distribution of main OM sources (terrestrial and marine) in the sediments indicate that algal and aquatic macrophyte derived OM inputs dominated over terrigenous plant sources. The lignin-derived methoxyphenol assemblage, dominated by vinylguaiacol and vinylsyringol derivatives in all sediments, points to large OM contribution from higher plants. The spatial distributions of PAHs (polyaromatic hydrocarbons) showed that most pollution sources were mixed sources including both pyrogenic and petrogenic. Low carbon preference indexes (CPI > 1) for n-alkanes, the presence of UCM (unresolved complex mixture) and the distribution of hopanes (C-29-C-36) and steranes (C-27-C-29) suggested localized petroleum-derived hydrocarbon inputs to the core sediments. Series of LABs were found in most sediment samples also pointing to domestic sewage anthropogenic contributions to the sediment OM.EU Erasmus Mundus Joint Doctorate fellowship (FUECA, University of Cadiz, Spain)EUEuropean Commission [FP7-ENV-2011, 282845, FP7-534 ENV-2012, 308392]MINECO project INTERCARBON [CGL2016-78937-R]info:eu-repo/semantics/publishedVersio

The Natural environment and the biogeochemical cycles

430p. : ill. ; 25 cm

Field Validation of Polyethylene Passive Air Samplers for Parent and Alkylated PAHs in Alexandria, Egypt

Polyethylene samplers (PEs) were deployed at 11 locations in Alexandria, Egypt during summer and winter to test and characterize them as passive samplers for concentrations, sources, and seasonal variations of atmospheric concentrations of polycyclic aromatic hydrocarbons (PAHs). PE-air equilibrium was attained faster for a wider range of PAHs during the winter season possibly due to increased wind speeds. Calculated PE-air partitioning constants, K PE-A, in our study [Log KPE-A = 0.9426 × Log K OA - 0.022 (n = 12, R2 = 0.99, Std error = 0.053)] agreed with literature values within \u3c46%. For parent (except naphthalene), mono- and dialkylated PAHs, active sampling based concentrations of PAHs were within an average factor of 1.4 (1.0-5.6) compared to the PE based values. For C 3-4 alkylated PAHs, KPE-A values were lower than predicted, on average by ∼0.8 log units per carbon in the alkylation. Enthalpies of vaporization (δHvap) accurately corrected K PE-As for temperature differences between winter and summer sampling. PAH profiles were dominated by naphthalene, phenanthrene, and alkylated phenanthrenes. Calculated diagnostic ratios indicated that PAHs originated mainly from vehicle emissions. © 2012 American Chemical Society