Partitioning Of Pollutants Research Articles

Investigating the Partition of Metalloid Pollutants in Gold Mine Tailings by STEM-EELS Spectrum Image

Investigating the Partition of Metalloid Pollutants in Gold Mine Tailings by STEM-EELS Spectrum Image

Interference between di(2-ethylhexyl) phthalate and heavy metals (Cd and Cu) in a Mollisol during aging and mobilization.

Diffuse pollution of the soil by phthalates and heavy metals causes numerous concerns. Their respective fates when coexisting require further investigation. In this study, di(2-ethylhexyl) phthalate (DEHP) and Cd/Cu were used as subjects, focusing on their behavior in Mollisols under combined pollution based on their concentration, fractionation, and leaching. The results indicated that when the two pollutants coexist, the dissipation rate of DEHP in the soil decreased, and its half-life was extended from 30.81 to 40.53 (Cd) and 35.40 d (Cu). DEHP altered the distribution of Cd and Cu in the soil, and this effect persisted after most of the DEHP had degraded. Leaching tests showed that the interaction of DEHP with Cd and Cu hindered leaching during the first rainfall event, but as DEHP degraded and Cd/Cu stabilized, the trapped pollutants were gradually released in subsequent rainfall events. Additionally, to investigate the partitioning of pollutants between soil water and solid surfaces, a diffusion model of DEHP and metal ions on the surface of montmorillonite (high specific surface area adsorbents abundant in soils) was built using molecular dynamics simulations. Simulations revealed their density distribution on the clay surface increased synergistically, whereas their diffusion was antagonistic. This study provides basic data and theoretical support concerning the ecological risk assessment of combined phthalate and heavy metals pollution in soil.

Partitioning and sources of microbial pollution in the Venice Lagoon

Microbial pollutants are a serious threat to human and environmental health in coastal areas. Based on the hypothesis that pollution from multiple sources may produce a distinct microbial signature and that microbial pollutants seem to distribute between a free-living and a particle-attached fraction, we investigated the occurrence, partitioning and sources of microbial pollutants in water samples collected in the Venice Lagoon (Italy). The area was taken as a case study of an environment characterized by a long history of industrial pollution and by growing human pressure. We found a variety of pollutants from several sources, with sewage-associated and faecal bacteria accounting for up to 5.98% of microbial communities. Sewage-associated pollutants were most abundant close to the city centre. Faecal pollution was highest in the area of the industrial port and was dominated by human inputs, whereas contamination from animal faeces was mainly detected at the interface with the mainland. Microbial pollutants were almost exclusively associated with the particle-attached fraction. The samples also contained other potential pathogens. Our findings stress the need for monitoring and managing microbial pollution in highly urbanized lagoon and semi-enclosed systems and suggest that management plans to reduce microbial inputs to the waterways should include measures to reduce particulate matter inputs to the lagoon. Finally, High-Throughput Sequencing combined with computational approaches proved critical to assess water quality and appears to be a valuable tool to support the monitoring of waterborne diseases.

Source apportionment of environmentally persistent free radicals (EPFRs) and heavy metals in size fractions of urban arterial road dust

The partitioning of pollutants in the size-fractions of road dust particles is extremely important to their migration and bioavailability in the air environment. Herein, the pollution characteristics and sources of heavy metals (As, Cd, Cu, Cr, Pb, Zn, Co, Mn, Ni) and environmentally persistent free radicals (EPFRs) are investigated in 64 samples of mixed particle-size road dust in four size fractions (>250 µm, 150–250 µm, 75–150 µm,<75 µm). The samples were collected from urban arterial roads of three cities in the core of Central Plains Urban Agglomeration. The results indicate that 67.70% of the road dust (by mass) consist of the<75 µm particles size fraction, and that the highest levels of EPFRs and heavy metals are concentrated in the<150 µm and< 75 µm size fractions. In addition, Cd exhibits extremely high average enrichment factors (EFs) of 51.84 in the 75–150 µm fraction and 64.80 in the<75 µm fraction. Further analysis reveals a remarkable correlation between EPFR concentration and the concentrations Zn and Cr in the road dust. An application of principal component analysis (PCA) and positive matrix factorization (PMF) to the regional investigation and the layout of functional zones demonstrates that Cr, Pb, Zn and EPFRs are mainly derived from traffic emissions, and account for 51.45–77.86% of the fine particle fraction (<150 µm). Meanwhile, industrial activities are identified as the primary source of Cd and Cu, accounting for 63.07–76.22% of the<150 µm particle size fraction. These findings suggest a potential risk of EPFRs and heavy metals in fine particulate matter, and provide a new insight into the potential sources and health risks of EPFRs in road dust. Therefore, further studies are needed in order to explore the EPFRs in fine particulate particles and to assess their effects upon human health.

Photocatalytic Hydrogels with a High Transmission Polymer Network for Pollutant Remediation

Efficient heterogeneous and metal-free photocatalysts have recently been targeted as reusable materials for pollutant remediation. However, poor light penetration into photocatalytic materials currently limits modern photocatalytic systems due to uneven performance across the photocatalytic material and inefficient light usage. Here, we present a classical photocatalytic polymer hydrogel composed of a high transmittance polymer network and small conjugated photocatalytic moieties. Radical copolymerization of a photocatalytically active benzothiadiazole acrylamide monomer with water-compatible N,N-dimethylacrylamide produced a photocatalytic hydrogel where only the photocatalytic moiety absorbs visible light. The photocatalytic hydrogel network enables easy partitioning of pollutants into the gel network, where they are photocatalytically degraded. The versatility and reusability of the photocatalytic material were demonstrated for degradation of both inorganic metal and organic contaminants, including N-(phosphonomethyl)glycine (glyphosate), the most commonly used herbicide. Furthermore, the potential of this material was explored in large-scale experiments, where glyphosate could be readily photodegraded at a half liter scale.

The effect of rainfall runoff on phase partition of palladium in receiving water bodies and the underlying influential mechanism

The influx of rainfall runoff intensifies phase partition of the pollutant in receiving water bodies, and the phase partition plays an important role in the speciation transformation and spatial partition of pollutants. In this study, the Meishe River on Hainan Island, China, was adopted as the research area, and palladium (Pd) was selected as the target pollutant. The purpose of this study was to explore phase partition of Pd in receiving water bodies and the underlying influential mechanism. The partition coefficients (Kds) of Pd between water and suspended particulate matter in receiving water bodies and rainfall runoff were 0.74 (0.1 × 10−2 - 8.75) and 2.74 (0.5 × 10−2 - 15.70), respectively. These results indicated that Pd dominated the dissolved phase in the receiving water bodies and that Pd dominated the particulate phase in rainfall runoff. Variations in the Kd value of Pd in the receiving water bodies were relatively smooth over time during the precipitation events in May and June. There were no significant differences in phase partition of Pd between the receiving water bodies and rainfall runoff. The Kd value for Pd in the receiving water bodies showed a fluctuating upward trend over time during the precipitation events in August, and the difference in Kd values of Pd between the receiving water bodies and the rainfall runoff were large. Variations in the Kd value of Pd among sections of the receiving water bodies could be roughly divided into two categories, namely, U and inverted-U types. After rainfall runoff converged for 20–25 min, the Pd phase transitions were more frequent within 7 m downstream of the outfall. The Kd value of Pd in the receiving water bodies was correlated with pH, Eh, and total suspended solid (TSS), and the correlation coefficients were 0.52, −0.57, and 0.84, respectively (p < 0.05). Compared with rainfall runoff, pH, Eh, TSS had less influence on phase partition of Pd in receiving water bodies. This might be attributed to the dilution effect of natural water and the unique dynamic mechanism of rivers.

Tap water contamination: Multiclass endocrine disrupting compounds in different housing types in an urban settlement

Contamination of endocrine disrupting compounds (EDCs) in tap water is an emerging global issue, and there are abundant influencing factors that have an ambivalent effect on their transportation and fate. Different housing types vary in terms of water distribution system operation and design, water consumption choices, and other hydraulic factors, which potentially affect the dynamics, loadings, and partitioning of pollutants in tap water. Thus, this study analyzed 18 multiclass EDCs in tap water from different housing types (i.e., landed and high-rise) and the associated health risks. Sample analyses revealed the presence of 16 EDCs, namely hormones (5), pharmaceuticals (8), a pesticide (1), and plasticizers (2) in tap water, with the prevalent occurrence of bisphenol A up to 66.40 ng/L in high-rise housing. The presence of caffeine and sulfamethoxazole distribution in tap water was significantly different between landed and high-rise housings (t(152) = −2.298, p = 0.023 and t(109) = 2.135, p = 0.035). Moreover, the salinity and conductivity of tap water in high-rise housings were significantly higher compared to those in landed housings (t(122) = 2.411, p = 0.017 and t(94) = 2.997, p = 0.003, respectively). Furthermore, there were no potential health risks of EDCs (risk quotient < 1) estimated in different age groups via drinking water intake. However, EDC variation in different housing types requires simulation of the occurrence, transport, and fate of EDCs in the distribution system and investigation of the underlying factors for effective mitigation, prevention, and intervention.

Populus alba tolerates and efficiently removes caffeine and zinc excesses using an organ allocation strategy

Mixed inorganic and organic contaminations are one of the main challenges in phytoremediation, due to the higher complexity derived by pollutant interactions and the increase of phytotoxicity. The cultivation of fast-growing poplars for removing contaminants from water could be a low-cost and flexible choice. The main objective of this study was to evaluate the tolerance of a poplar species (Populus alba ‘Villafranca’ clone) to irrigation with water contaminated with zinc (Zn) and caffeine (CFN). Poplars were maintained in hydroponic and exposed to four different treatments (Control, CFN, Zn and Zn + CFN) over 7 days. Poplar showed a good tolerance to Zn and CFN treatments, without any symptom of phytotoxicity. However, the type of treatment affected the contaminant dynamics in the plant-water system and a pollutant partitioning was observed among organs, with a higher accumulation of Zn in root (472 ± 128.7 mg kg− 1 DW) and CFN in shoot (30 ± 4.5 µg g− 1 FW). Under mixed condition, the CFN uptake significantly increased in root (+ 40%) and stem (+ 28%) while the Zn concentration decreased in leaves (-19%). A focus on the potential role of natural resistance-associated macrophage proteins (NRAMPs) in divalent metal transport has been performed. A down-regulation of NRAMP1.3 was detected in roots of plants exposed to CFN treatment in relation to an increase of Mn concentration. Data confirmed the suitability of Populus alba for the remediation of multi contaminated water.

Soils in lakes: the impact of inundation and storage on surface water quality.

The large-scale storage and inundation of contaminated soils and sediments in deep waterlogged former sand pits or in lakes have become a fairly common practice in recent years. Decreasing water depth potentially promotes aquatic biodiversity, but it also poses a risk to water quality as was shown in a previous study on the impact on groundwater. To provide in the urgent need for practical and robust risk indicators for the storage of terrestrial soils in surface waters, the redistribution of metals and nutrients was studied in long-term mesocosm experiments. For a range of surface water turbidity (suspended matter concentrations ranging from 0 to 3000mg/L), both chemical partitioning and toxicity of pollutants were tested for five distinctly different soils. Increasing turbidity in surface water showed only marginal response on concentrations of heavy metals, phosphorus (P) and nitrogen (N). Toxicity testing with bioluminescent bacteria, and biotic ligand modelling (BLM), indicated no or only minor risk of metals in the aerobic surface water during aerobic mixing under turbid conditions. Subsequent sedimentation of the suspended matter revealed the chemical speciation and transport of heavy metals and nutrients over the aerobic and anaerobic interface. Although negative fluxes occur for Cd and Cu, most soils show release of pollutants from sediment to surface waters. Large differences in fluxes occur for PO4, SO4, B, Cr, Fe, Li, Mn and Mo between soils. For an indicator of aerobic chemical availability, dilute nitric acid extraction (0.43M HNO3; Aqua nitrosa) performed better than the conventional Aqua regia destruction. Both the equilibrium concentrations in surface waters, and fluxes from sediment, were adequately (r2 = 0.81) estimated by a 1mM CaCl2 soil extraction procedure. This study has shown that the combination of 0.43M HNO3 and 1mM CaCl2 extraction procedures can be used to adequately estimate emissions from sediment to surface waters, and assess potential water quality changes, when former sand pits are being filled with soil materials.

Predicting plant cuticle-water partition coefficients for organic pollutants using pp-LFER model

Predicting plant cuticle-water partition coefficients (Kcw) and understanding the partition mechanisms are crucial to assess environmental fate and risk of organic pollutants. Up to now, experimental Kcw values are determined for only hundreds of compounds because of high experimental cost. For this reason, computational models, which can predict Kcw values based on chemical structures, are promising approaches to evaluate new compounds. In this study, a large dataset consisting of 279 logKcw values for 125 unique compounds were collected and curated. A poly-parameter linear free energy relationship (pp-LFER) model was developed with stepwise multiple linear regression based on this dataset. The resulted pp-LFER model has good predictability and robustness as indicated by determination coefficient (R2adj,tra) of 0.93, bootstrapping coefficient (Q2BOOT) of 0.92, external validation coefficient (Q2ext) of 0.94 and root mean square error of 0.52 log units. Contribution analysis of different interactions indicated that dispersion and hydrophobic interactions have the highest positive contribution (56%) to increase the partition of pollutants onto plant cuticles. In addition, for organic pollutions containing benzene ring (13–31%), double bond (9–17%) or nitrogen-containing heterocycles (9–17%), π/n-electron pairs interactions exhibit obvious positive contributions to logKcw. In conclusion, the proposed pp-LFER model is beneficial for predicting logKcw of potential organic pollutants directly from their molecular structures.

Development and optimization of a plunger assisted solvent extraction method for polycyclic aromatic hydrocarbons sampled onto multi-channel silicone rubber traps

A plunger assisted solvent extraction (PASE) method for multi-channel silicone rubber trap samplers was developed and evaluated as an alternative to direct thermal desorption for the monitoring of polycyclic aromatic hydrocarbons (PAHs). The proposed extraction method was simple, fast (a total of 2 min for extraction), and used a small volume of solvent (a total of 2 mL from two sequential 1 mL extractions). The PASE method presented an advantage over thermal desorption in that samples could be re-analyzed, as only a portion of the extract was injected. Additionally, this approach is cost effective and can be applied in laboratories which do not have thermal desorption systems, hence allowing for the more widespread use of the polydimethylsiloxane samplers which can be employed as denuders in the monitoring of gas and particle partitioning of air pollutants. The method was validated over a wide concentration range (0.005–10 ng μL−1) and the limits of detection ranged from 13.6 ng m−3 for naphthalene to 227.1 ng m−3 for indeno[1,2,3-cd]pyrene. Overall extraction efficiencies of the target PAHs were good (from 76% for naphthalene to 99% for phenanthrene) with relative standard deviations below 6%. The PASE method was successfully applied to the analysis of domestic fire air emission samples taken at 10 and 20 min after ignition, using a sampling flow rate of 500 mL min−1 for 10 min in each case. The samples were found to contain primarily naphthalene (maximum concentration of 9.5 μg m−3, 10 min after ignition), as well as fluorene, anthracene, phenanthrene, fluoranthene and pyrene.

Atmospheric concentrations and gas-particle partitioning of PCDD/Fs and dioxin-like PCBs around Hochiminh city

Atmospheric PCDD/Fs and dl-PCBs samples were collected in Hochiminh city, Vietnam to address the effect of meteorological parameters, especially rainfall, on the occurrence and gas/particle partitioning of these persistent organic pollutants. The results indicate that PCDD/Fs and dl-PCBs concentrations in industrial site are higher than those measured in commercial and rural sites during both rainy and dry seasons. In terms of mass concentration, ambient PCDD/F levels measured in dry season are significantly higher than those measured in rainy season while dl-PCB levels do not vary significantly between rainy and dry seasons. The difference could be attributed to different gas/particle partitioning characteristics between PCDD/Fs and dl-PCBs. PCDD/Fs are found to be mainly distributed in particle phase while dl- PCBs are predominantly distributed in gas phase in both rainy and dry seasons. Additionally, Junge-Pankow and Harner-Bidleman models are applied to better understand the gas/particle partitioning of these pollutants in atmosphere. As a results, both PCDD/Fs and dl-PCBs are under non-equilibrium gas/particle partitioning condition, and PCDD/Fs tend to reach equilibrium easier in rainy season while there are no clear trend for dl-PCBs. Harner-Bidleman model performs better in evaluating the gas/particle partitioning of PCDD/Fs while Junge-Pankow model results in better prediction for dl-PCBs.

Distribution of persistent organic pollutants in aggregate fractions of a temperate forest and semi-rural soil

The fate of persistent organic pollutants (POPs) and their interactions with aggregates of forest soils are not completely understood. Our objectives here were to quantify the distribution of different POPs in water-stable aggregate fractions and to study their influence on soil organic carbon (Corg) content. Soil samples were taken from a forest-site, Gogerddan (G) and a semi-rural site, Hazelrigg (H) in Great Britain, from 0–2 and 2–5 cm and 0–4 and 8–12 cm soil depth, respectively. POPs analyzed were PAHs, PCBs, total DDT, PBDEs and HCB. The bulk soil analysis showed that the concentration of POPs was significantly higher (p ≤ 0.05) in forest site G than in semi-rural site H, particularly at the surface soil levels compared to the subsurface soil depths in both sites. Total concentrations of PCBs and PAHs of both sites were positively correlated with Corg contents. POPs concentrations and Corg, Nt contents of forest site G were significantly higher (p ≤ 0.05) in water-stable macro aggregates (>0.25, >1, >2 mm) than the micro aggregates (>0.053 mm). The POP concentrations of all aggregate fractions after normalizing to their respective Corg content were increased due higher contamination and strong sorption by Corg. These results showed a strong effect of Corg on the partitioning of organic pollutants to soil aggregate size fractions. The present study affirms the ecological significance of forest soils act as a potential sink of POPs. In summary, our results suggest that aggregate fractions may promote soil C storage and act as a potential POP sink in surface soil without increasing their concentration in the aggregate fraction of subsoil.

Interaction of engineered nanomaterials with hydrophobic organic pollutants

As nanomaterials become an increasing part of everyday consumer products, it is imperative to monitor their potential release during production, use and disposal, and to assess their impact on the health of humans and the ecosystem. This necessitates research to better understand how the properties of engineered nanomaterials (ENMs) lead to their accumulation and redistribution in the environment, and to assess whether they could become novel pollutants or if they can affect the mobility and bioavailability of other toxins. This study focuses on understanding the influence of nanostructured-TiO2 and the interaction of multi-walled carbon nanotubes with organic pollutants in water. We studied the adsorption and water phase dispersion of model pollutants with relatively small water solubility (i.e., two- and three-ring polyaromatic hydrocarbons and insecticides) with respect to ENMs. The sorption of pollutants was measured based on water phase analysis, and by separating suspended particles from the water phase and analyzing dried samples using integrated thermal–chromatographic–mass spectroscopic (TGA/GC/MS) techniques. Solid phase analysis using a combination of TGA/GC/MS is a novel technique that can provide real-time quantitative analysis and which helps to understand the interaction of hydrophobic organic pollutants and ENMs. The adsorption of these contaminants to nanomaterials increased the concentration of the contaminants in the aqueous phase as compared to the ‘real’ partitioning due to the octanol–water partitioning. The study showed that ENMs can significantly influence the adsorption and dispersion of hydrophobic/low water soluble contaminants. The type of ENM, the exposure to light, and the water pH have a significant influence on the partitioning of pollutants.

Polycyclic aromatic hydrocarbons (PAHs) in water and sediment from a river basin: sediment-water partitioning, source identification and environmental health risk assessment.

The information on concentration levels, partitioning and sources of pollutants in aquatic environment is quite necessary for pollution treatment and quality criteria. In this work, sixteen priority polycyclic aromatic hydrocarbons (PAHs) recommended by U.S. Environmental Protection Agency in the water and sediment of Yinma River Basin were firstly investigated. Among 16 individual PAHs, naphthalene was the highest average concentration in water samples as well as in sediment samples, 67.2ng/L and 825.06ng/g, respectively, whereas benzo(g,h,i)perylene was undetected in water samples nor in sediment samples. For three PAH compositional patterns, concentrations of light (2-3 ring) PAHs were dominant in water and sediment, accounting for 71.69 and 86.98% respectively. The PAH partitioning in the sediment-water system was studied, results showed that PAH partitioning was in an unsteady state and tended to accumulate in the sediment. The possible sources of PAHs in water and sediment were both identified as a mixed source of petroleum and combustion. The benzo(a)pyrene equivalents (EBaP) values for PAHs in the water and sediment in some sites were relatively higher, suggesting the existence of environmental health risk.

Assessment of combined electro–nanoremediation of molinate contaminated soil

Molinate is a pesticide widely used, both in space and time, for weed control in rice paddies. Due to its water solubility and affinity to organic matter, it is a contaminant of concern in ground and surface waters, soils and sediments. Previous works have showed that molinate can be removed from soils through electrokinetic (EK) remediation.In this work, molinate degradation by zero valent iron nanoparticles (nZVI) was tested in soils for the first time. Soil is a highly complex matrix, and pollutant partitioning between soil and water and its degradation rates in different matrices is quite challenging. A system combining nZVI and EK was also set up in order to study the nanoparticles and molinate transport, as well as molinate degradation.Results showed that molinate could be degraded by nZVI in soils, even though the process is more time demanding and degradation percentages are lower than in an aqueous solution. This shows the importance of testing contaminant degradation, not only in aqueous solutions, but also in the soil-sorbed fraction. It was also found that soil type was the most significant factor influencing iron and molinate transport. The main advantage of the simultaneous use of both methods is the molinate degradation instead of its accumulation in the catholyte.

Importance of soil organic matter for the diversity of microorganisms involved in the degradation of organic pollutants

Many organic pollutants are readily degradable by microorganisms in soil, but the importance of soil organic matter for their transformation by specific microbial taxa is unknown. In this study, sorption and microbial degradation of phenol and 2,4-dichlorophenol (DCP) were characterized in three soil variants, generated by different long-term fertilization regimes. Compared with a non-fertilized control (NIL), a mineral-fertilized NPK variant showed 19% and a farmyard manure treated FYM variant 46% more soil organic carbon (SOC). Phenol sorption declined with overall increasing SOC because of altered affinities to the clay fraction (soil particles <2 mm in diameter). In contrast, DCP sorption correlated positively with particulate soil organic matter (present in the soil particle fractions of 63-2000 μm). Stable isotope probing identified Rhodococcus, Arthrobacter (both Actinobacteria) and Cryptococcus (Basidiomycota) as the main degraders of phenol. Rhodococcus and Cryptococcus were not affected by SOC, but the participation of Arthrobacter declined in NPK and even more in FYM. (14)C-DCP was hardly metabolized in the NIL variant, more efficiently in FYM and most in NPK. In NPK, Burkholderia was the main degrader and in FYM Variovorax. This study demonstrates a strong effect of SOC on the partitioning of organic pollutants to soil particle size fractions and indicates the profound consequences that this process could have for the diversity of bacteria involved in their degradation.

Improved 3D-QSPR analysis of the predictive octanol–air partition coefficients of hydroxylated and methoxylated polybrominated diphenyl ethers

The octanol/air partition coefficient (KOA) is a key physicochemical parameter for describing the partition of organic pollutants between air and environment organic phase. The development of appropriate method to estimate KOA is of great importance. In the present study, the steric, electrostatic, hydrophobic, hydrogen bond donor and acceptor descriptors were computed by comparative molecular field analysis (CoMFA) and comparative molecular similarity indices analysis (CoMSIA). On the basis of these parameters, the statistically quantitative structure–property relationship (QSPR) models for logKOA of hydroxylated polybrominated diphenyl ethers (OH-PBDEs) and methoxylated polybrominated diphenyl ethers (MeO-PBDEs) congeners were developed using partial least-squares (PLS) analysis, of which the R2 is about 0.980, 0.952 respectively. The electrostatic field was found to be main factors governing the logKOA. The results of validation indicate the models of this study exhibit optimum stability, and thus it is feasible to predict logKOA.

Partitioning of polycyclic aromatic hydrocarbons, alkylphenols, bisphenol A and phthalates in landfill leachates and stormwater

Partitioning of organic pollutants is essential to their fate, mobility and removal from water and soil. To study the partitioning behavior of selected alkylphenols, bisphenol A, phthalates and polycyclic aromatic hydrocarbons (PAHs), a method for separating the truly dissolved and colloidal phase of organic pollutants was developed, verified and applied to samples of landfill leachate and stormwater from urban areas and waste-sorting sites.Alkylphenols, bisphenol A, phthalates and PAHs were detected in all the untreated samples (total concentrations), most of the filtered samples and frequently in the colloid-bound phase. Concentrations of alkylphenols and PAHs in urban stormwater were one order of magnitude lower than in the landfill leachates and stormwater from waste-sorting sites.The difference between total, dissolved and colloid-bound concentrations in the water samples was not statistically significant for any phenols or phthalates, but for three of the PAHs; naphthalene (mostly dissolved), phenanthrene and fluoranthene (mostly particulate). These results indicate that in landfill leachates and stormwaters, organic pollutants are predominantly attached to colloids and/or truly dissolved in contrast to their expected strong sorption to particulate matter. Occurrence and concentrations of pollutants in dissolved and colloid-bound phases correlated negatively with the KOW. However, even highly hydrophobic compounds were frequently detected in filtered samples, i.e. the dissolved phases, and it is suggested that the organic content in the colloids decreases the compounds' partition to particles. The results confirm that the KOW values of specific organic pollutants well describe the compounds partition-binding process to dissolved organic carbon (DOC) colloids. Our findings call for a re-assessment of the organic pollutants' mobility and associated risks. This knowledge can also serve as a base for selecting efficient treatment methods for stormwater and landfill leachates.

Improvement of aquatic pollutant partition coefficient correlations using 1D molecular descriptors — chlorobenzene case study

AbstractPartition coefficients between environmental compartments are essential parameters in any predictive models on pollutants’ fate in various emission scenarios. When sufficient experimental data are not available, empirical algebraic models are capable of predicting the pollutant partitioning characteristics based on bulk physico-chemical properties or various molecular structural features. When the use of sophisticated rules based on detailed 2D–3D molecular descriptors is not available as a quick option, inexpensive, simple correlations based solely on octanol-1-ol (octanol)-water partition coefficients (K ow) are extensively employed. The present study investigates enhancing the adequacy of such hydrophobicity-based models by adding simple 1D descriptors, readily identifiable by inspecting the substance structure (i.e. the number of chlorine atoms bound to aromatic rings, or the number of aromatic 5- or 6-atom rings, etc.), in addition to the pollutant’s solubility in water. Exemplification is made for predicting the water-biota (fish)-sediment partition coefficients for chlorobenzenes (CBz).