Contribution of ingestive/dietary uptake to bioaccumulation of organics in worms.

Ingestive uptake is critical for understanding the accumulation and trophic transfer of chemicals and synthesized particles in general. This study explored the contribution of ingestion in the bioaccumulation of chemicals focusing on worms. Novel theory and equations were developed to derive fractional ingestive contribution, f, from a broad range of dietary uptake and accumulation studies, and to build a small dataset of f (n = 43) from relevant toxicokinetic and bioaccumulation measurements.

How effective is score-based data quality assessment? An illustration with fish BCF data.

Increasingly rigorous data quality (DQ) evaluations and/or screening practices are being applied to environmental and ecotoxicological datasets. DQ is predominantly evaluated by scoring given data against preselected criteria. This study provides the first examination on the effectiveness of score-based DQ evaluation in providing statistically meaningful differentiation of measurements using fish bioconcentration factor (BCF) dataset as an illustration.

Rapid debromination of tetrabromobisphenol A by Cu/Fe bimetallic nanoparticles in water, its mechanisms, and genotoxicity after treatments.

Tetrabromobisphenol A (TBBPA), a widely used brominated flame retardants, has been detected in various environmental matrices and is known to cause various adverse effects on human bodies. This study examined the feasibility and effectiveness of remediating TBBPA using Cu/Fe bimetallic nanoparticles (Cu/Fe BNPs) at various environmental and operational conditions. In general, TBBPA removal rate and debromination efficiency increased with higher Cu doping, higher Cu/Fe BNPs loading, higher temperature, and lower pH.

Determination of In Vivo Biotransformation Kinetics Using Early-Time Biota Concentrations.

Technical challenges have hampered the characterization of biotransformation kinetics-a critical link in understanding and predicting the toxicokinetics and ecotoxicology of organic compounds. A shortcut approach to characterize the in vivo biotransformation rate constant (k ) with incomplete pathway or metabolite details was proposed. The value of k can be derived as , with f (t) being the molar equivalent fraction of the parent compound (PC) at an early time t in both constant exposure and decay source chemical uptake scenarios.

A Reduced Model for Bioconcentration and Biotransformation of Neutral Organic Compounds in Midge.

A bioconcentration factor (BCF) database and a toxicokinetic model considering only biota-water partitioning and biotransformation were constructed for neutral organic chemicals in midge. The database contained quality-reviewed BCF and toxicokinetic data with variability constrained to within 0.5 to 1 log unit.

Removal, seasonal variation, and environmental impact of parabens in a municipal wastewater treatment facility in Guangzhou, China.

The occurrence, seasonal variation, and environmental impact of five widely used parabens, methyl-(MeP), ethyl-(EtP), n-propyl-(n-PrP), n-butyl-(n-BuP), and benzyl-(BzP) parabens, were investigated in a municipal wastewater treatment plant (WWTP) located in Guangzhou, China, for 1 year. The concentrations of ∑parabens in the influent and the effluent were 94.2-957 and 0.

Removal of hexabromocyclododecane by carboxymethyl cellulose stabilized Fe and Ni/Fe bimetallic nanoparticles: The particle stability and reactivity in water.

Aggregation of nanoparticles (NPs) can hinder the degradative reactivity of particles towards organic pollutants as it reduces available surface area for reaction. This limitation may be circumvented by applying dispersant to improve colloidal stability of nanoparticle suspension. This study examined the removal of hexabromocyclododecane (HBCD), a recently listed persistent organic pollutant, by carboxymethylcellulose (CMC) stabilized nanoscale zerovalent iron (CMC-NZVI) and bimetallic Ni/Fe nanoparticles (CMC-Ni/Fe) under the influence of suspension chemistry.

Occurrence, seasonal variation and environmental impact of phosphorus flame retardants in a large scale wastewater treatment plant.

The occurrence, seasonal variation and emission of nine widely used phosphorus flame retardants (PFRs) were investigated in a wastewater treatment plant (WWTP) located in Guangzhou, China, over 1 year. Results showed that PFRs were widely detected in wastewater and sewage sludge. Tris(2-chloroisopropyl) phosphate (TCIPP) was the most dominant PFRs in influent, effluent, and sludge.

Assessing pollution and risk of polycyclic aromatic hydrocarbons in sewage sludge from wastewater treatment plants in China's top coal-producing region.

Managing and disposing of sewage sludge have been a severe environmental challenge around the world. China produces hundreds of million tons of sewage sludge annually, and a better understanding of the extent and risk of the associated pollution is of critical importance for implementing environmentally safe regulations and practices. The present study examined the quantity, composition, source, and risk of polycyclic aromatic hydrocarbons (PAHs) in sewage sludge from 18 wastewater treatment plants (WWTPs) in Shaanxi, one of China's top coal-producing provinces.

Sorption of organic compounds to two diesel soot black carbons in water evaluated by liquid chromatography and polyparameter linear solvation energy relationship.

Substantial variability in sorption capacity of black carbon (BC) has been a major challenge for accurate fate and risk assessment of organic pollutants in soils and sediments. 16 model organic sorbates (logK = 0.38-4.

Organophosphorus flame retardants and heavy metals in municipal landfill leachate treatment system in Guangzhou, China.

The occurrence, distribution and removal efficiencies of organophosphorus flame retardants (OPFRs) and metals were examined in a municipal landfill leachate treatment system in Guangzhou, China. Five OPFRs and thirty-five metals were detected in wastewater samples collected at different treatment stages. ∑OPFRs was reduced from 4807.

Bioconcentration model for non-ionic, polar, and ionizable organic compounds in amphipod.

The present study presents a bioconcentration model for non-ionic, polar, and ionizable organic compounds in amphipod based on first-order kinetics. Uptake rate constant k is modeled as logk1=10.81logKOW + 0.

Sorption and desorption kinetics of nitroglycerin and 2,4-dinitrotoluene in nitrocellulose and implications for residue-bound energetic materials.

Energetic materials (EMs) bound to propellant residues can contribute to environmental risk and public health concerns. This work investigated how nitrocellulose, a common binding material in propellants, may control the release dynamics of nitroglycerin (NG) and 2,4-dinitrotoluene (2,4-DNT) from propellant residues. Batch adsorption/desorption experiments on nitrocellulose and re-interpretation on results from past leaching studies involving propellant-bound EMs were conducted.

Bioconcentration factors and plant-water partition coefficients of munitions compounds in barley.

Plants growing in the soils at military ranges and surrounding locations are exposed, and potentially able to uptake, munitions compounds (MCs). The extent to which a compound is transferred from the environment into organisms such as plants, referred to as bioconcentration, is conventionally measured through uptake experiments with field/synthetic soils. Multiple components/phases that vary among different soil types and affect the bioavailability of the MC, however, hinder the ability to separate the effects of soil characteristics from the MC chemical properties on the resulting plant bioconcentration.

Removal Efficiency and Risk Assessment of Polycyclic Aromatic Hydrocarbons in a Typical Municipal Wastewater Treatment Facility in Guangzhou, China.

The loading and removal efficiency of 16 US EPA polycyclic aromatic hydrocarbons (PAHs) were examined in an inverted A²/O wastewater treatment plant (WWTP) located in an urban area in China. The total PAH concentrations were 554.3 to 723.

Leaching of propellant compounds from munition residues may be controlled by sorption to nitrocellulose.

Sustainable management of military ranges requires effective assessment of surface mobility and leaching potential of propellant compounds (PCs). Previous studies have focused mostly on PCs' dissolution from fired residues and their sorption to soil components. This work investigated the potential role of nitrocellulose, a major component in propellants, in the binding of PCs to propellant residues.

Occurrence of PBDEs and alternative halogenated flame retardants in sewage sludge from the industrial city of Guangzhou, China.

This study investigated the prevalence and abundance of halogenated flame retardants (HFRs) in sludge samples from 5 sewage treatment plants in Guangzhou, China. Detection of 18 polybrominated diphenyl ethers (PBDEs), 9 alternative HFRs including Dechlorane Plus (DP), brominated alkylbenzenes, and polybrominated biphenyls, and 2 related degradation products was conducted. Decabromodiphenyl ether (BDE 209) and decabromodiphenyl ethane (DBDPE) were the dominant HFRs, with concentrations ranging from 200 to 2150 ng/g and 680-27,400 ng/g, respectively.

Experimental determination of solvent-water partition coefficients and Abraham parameters for munition constituents.

There is concern about the environmental fate and effects of munition constituents (MCs). Polyparameter linear free energy relationships (pp-LFERs) that employ Abraham solute parameters can aid in evaluating the risk of MCs to the environment. However, poor predictions using pp-LFERs and ABSOLV estimated Abraham solute parameters are found for some key physico-chemical properties.

Deriving in vivo biotransformation rate constants and metabolite parent concentration factor/stable metabolite factor from bioaccumulation and bioconcentration experiments: An illustration with worm accumulation data.

Growing concern for the biological fate of organic contaminants and their metabolites and the urge to connect in vitro and in vivo toxicokinetics have prompted researchers to characterize the biotransformation behavior of organic contaminants in biota. The whole body biotransformation rate constant (k ) is currently determined by the difference approach, which has significant methodological limitations. A new approach for determining k from the kinetic observations of the parent contaminant and its intermediate metabolites is proposed.

A reductionist mechanistic model for bioconcentration of neutral and weakly polar organic compounds in fish.

The bioconcentration factor (BCF) of neutral and weakly polar organic chemicals in fish is modeled using independently calibrated models of chemical partitioning (freely dissolved fraction of chemical in the aqueous phase [φsys ] and wet-weight fish-water partition coefficient [KFW ]), respiratory exchange (respiratory update rate constant [k1 ], and respiratory elimination rate constant [k2  = k1 /KFW ]), and biotransformation (whole-body biotransformation rate constant [kM ]) as BCF = φsys KFW /(1 + kM /k2 ). Existing k1 models tend to overestimate for chemicals with log KOW  < 3.5, which constituted 30% to 50% of the examined chemicals.

Biotransformation model of neutral and weakly polar organic compounds in fish incorporating internal partitioning.

A model for whole-body in vivo biotransformation of neutral and weakly polar organic chemicals in fish is presented. It considers internal chemical partitioning and uses Abraham solvation parameters as reactivity descriptors. It assumes that only chemicals freely dissolved in the body fluid may bind with enzymes and subsequently undergo biotransformation reactions.

Investigating desorption of native pyrene from sediment on minute- to month-timescales by time-gated fluorescence spectroscopy.

We investigated desorption of native pyrene from field-aged sediments using time-gated, laser-induced fluorescence (LIF) spectroscopy. LIF is superior to conventional analytical methods for the measurement of quickly changing dissolved pyrene because it allows observations at minute-scale resolution, has a low detection limit (approximately 1 ng/L), and minimizes sample loss and disturbance since it requires no system subsampling and chemical analysis. The efficacy of LIF was demonstrated in studies of pyrene desorption from Boston Harbor sediment segregated into different size-fractions (38-75, 75-106, and 180-250 microm diameter) and used in varying solid-to-water ratios (20, 70, and 280 mg(solid)/L).