Seasonal variability of formaldehyde production from photolysis of rainwater dissolved organic carbon

Photochemical production of formaldehyde (HCHO) was measured in rainwater from 13 precipitation events in Wilmington, North Carolina, USA under conditions of simulated sunlight. HCHO concentrations increased in all samples irradiated with no changes observed in dark controls. HCHO photoproduction rates were strongly correlated with dissolved organic carbon (DOC) suggesting HCHO was derived from direct or indirect photolysis of rainwater DOC. The higher photoproduction rates (0.03–2.9 μM h^?1) relative to those reported for surface waters suggests that rainwater DOC is more photolabile in terms of HCHO production than surface waters. HCHO photoproduction rates were higher in growing season (1.0 ± 1.0 μM h^?1) compared to non-growing season (0.08 ± 0.05 μM h^?1) even when rates were normalized for DOC (6.8 ± 3.6 μM h^?1 mM C^?1 versus 1.8 ± 1.0 μM h^?1 mM C^?1). The higher growing season rate may be related to seasonal differences in the composition of DOC as evidenced by differences in fluorescence per unit carbon of rainwater samples. Irradiation of C18 extracts of rainwater also produced HCHO, but at lower rates compared to corresponding whole rain samples, suggesting that hydrophyllic components of rainwater play a role in HCHO photoproduction. Our results indicate that photolysis of rainwater DOC produces significant amounts of HCHO, and possibly other low molecular weight organic compounds, likely increasing its reactivity and bioavailability.     

Methyl Tertiary Butyl Ether (MTBE) and Other Volatile Organic Compounds (VOCs) in Public Water Systems,Private Wells,and Ambient Groundwater Wells in New Jersey Compared to Regulatory and Human-Health Benchmarks

Potential threats to drinking water and water quality continue to be a major concern in many regions of the United States. New Jersey, in particular, has been at the forefront of assessing and managing potential contamination of its drinking water supplies from hazardous substances. The purpose of the current analysis is to provide an up-to-date evaluation of the occurrence and detected concentrations of methyl tertiary butyl ether (MTBE) and several other volatile organic compounds (VOCs) in public water systems, private wells, and ambient groundwater wells in New Jersey based on the best available data, and to put these results into context with federal and state regulatory and human-health benchmarks. Analyses are based on the following three databases that contain water quality monitoring data for New Jersey: Safe Drinking Water Information System (SDWIS), Private Well Testing Act (PWTA), and National Water Information System (NWIS). For public water systems served by groundwater in New Jersey, MTBE was detected at a concentration ≥10 μg/L, ≥20 μg/L, and ≥70 μg/L at least once in 30 (2%), 21 (1.4%), and five (0.3%) of sampled systems from 1997 to 2011, respectively. For private wells in New Jersey, MTBE was detected at a concentration ≥10 μg/L, ≥20 μg/L, and ≥70 μg/L at least once in 385 (0.5%), 183 (0.2%), and 46 (0.05%) of sampled wells from 2001 to 2011, respectively. For ambient groundwater wells in New Jersey, MTBE was detected at a concentration ≥10 μg/L, ≥20 μg/L, and ≥70 μg/L at least once in 14 (2.1%), 9 (1.3%), and 4 (0.6%) of sampled wells from 1993 to 2012, respectively. Average detected concentrations of MTBE, as well as detected concentrations at upper-end percentiles, were less than corresponding benchmarks for all three datasets. The available data show that MTBE is rarely detected in various source waters in New Jersey at a concentration that exceeds the State's health-based drinking water standard or other published benchmarks, and there is no evidence of an increasing trend in the detection frequency of MTBE. Other VOCs, such as tetrachloroethylene (PCE), trichloroethylene (TCE), and benzene, are detected more often above corresponding regulatory or human-health benchmarks due to their higher detected concentrations in water and/or greater toxicity values. The current analysis provides useful data for evaluating the nature and extent of historical and current contamination of water supplies in New Jersey and potential opportunities for public exposures and health risks due to MTBE and other VOCs on a statewide basis. Additional forensic or forecasting analyses are required to identify the sources or timing of releases of individual contaminants at specific locations or to predict potential future water contamination in New Jersey.     

Occurrence and behaviour of pharmaceutical compounds in a Portuguese wastewater treatment plant: Removal efficiency through conventional treatment processes

Wastewater treatments can eliminate or remove a substantial amount of pharmaceutical active compounds (PhACs), but there may still be significant concentrations of them in effluents discharged into surface water bodies. Beirolas wastewater treatment plant (WWTP) is located in the Lisbon area and makes its effluent discharges into Tagus estuary (Portugal). The main objective of this study is to quantify a group of 32 PhACs in the different treatments used in this WWTP. Twelve sampling campaigns of wastewater belonging to the different treatments were made in 2013–2014 in order to study their removal efficiency. The wastewaters were analysed by solid phase extraction (SPE) and ultra-performance liquid chromatography coupled with tandem mass detection (UPLC–MS/MS). The anti-diabetics were the most frequently found in wastewater influent (WWI) and wastewater effluent (WWE) (208 and 1.7 μg/L, respectively), followed by analgesics/antipyretics (135 μg/L and < LOQ, respectively), psychostimulants (113 and 0.49 μg/L, respectively), non-steroidal anti-inflammatory drugs (33 and 2.6 μg/L, respectively), antibiotics (5.2 and 1.8 μg/L, respectively), antilipidemics (1.6 and 0.24 μg/L, respectively), anticonvulsants (1.5 and 0.63 μg/L, respectively) and beta blockers (1.3 and 0.51 μg/L, respectively). A snapshot of the ability of each treatment step to remove these target PhACs is provided, and it was found that global efficiency is strongly dependent on the efficiency of secondary treatment. Seasonal occurrence and removal efficiency was also monitored, and they did not show a significant seasonal trend.     

Determination of Heavy Metals in Indoor Dust From Primary School (Sri Serdang,Malaysia): Estimation of the Health Risks

Heavy metal concentrations (Pb, Cd, and Cu) in classroom indoor dust were measured. The health risk (non-carcinogenic) of these heavy metals in classroom indoor dust to children was assessed based on United States Environmental Protection Agency health risk model. Indoor classroom dust samples were collected from 21 locations including windows, fans, and floors at a primary school in Sri Serdang, Malaysia. Classroom dust samples were processed using aqua regia method and analyzed for Pb, Cd, and Cu concentrations. The highest average heavy metal concentrations were found in windows, followed by floor and fan. Pb concentrations ranged from 34.17 μg/g to 101.87 μg/g, Cd concentrations ranged from 1.73 μg/g to 7.5 μg/g, and Cu concentrations ranged from 20.27 μg/g to 82.13 μg/g. Ventilation and cleaning process were found as the possible factors that contributed to heavy metal concentration in window, floor, and fan. Moreover, the hazard index (HI) and hazard quotient (HQ) values for heavy metals Cd and Cu were less than one. By contrast, the HI and HQ values for Pb (maximum values) were more than one, indicating potential non-carcinogenic risk to children. Long-term persistence of leaded petrol, building materials, interior paint, school located near industrial areas and major roads, as well as vehicle emission are the factors attributed to the presence of heavy metals in classroom dust. Further research under a long-term monitoring plan and actual values in a health risk model is crucial before a final decision on heavy metal exposure and its relationship to young children health risks can be made. Nevertheless, the findings of this study provide crucial evidence to include indoor dust quality in school assessment because the environmental processes and impacts of surrounding school area have health risk implications on young children.     

Sources of Volatile Organic Compounds in a University Building

A total of 34 volatile organic compounds (VOCs) were measured in the indoor of laboratories, offices and classrooms of the Chemical Engineering Department of Hacettepe University in Ankara in 2 week-day passive sampling campaigns. The average concentrations ranged from 0.77 to 265 μg m^?3 at the different indoor sites, with the most abundant VOC found to be toluene (119.6 μg m^?3), followed by styrene (21.24 μg m^?3), 2-ethyltoluene (17.11 μg m^?3), n-hexane (10.21 μg m^?3) and benzene (9.42 μg m^?3). According to the factor analysis, the evaporation of solvents used in the laboratories was found to be the dominant source.     

Occurrence of perchlorate in rice from different areas in the Republic of Korea

Perchlorate concentrations in rice samples from many different provinces, and correlation with surface water contamination, were investigated in the Republic of Korea. Perchlorate levels in the 51 rice samples purchased from local markets ranged from below the detection limit to 1.79?±?0.39 μg/kg with a mean level of 0.21 μg/kg and 7 samples collected from the Nakdong River watershed ranged from 0.38?±?0.1 to 3.23?±?0.47 μg/kg with a mean level of 0.9 μg/kg. The correlation coefficient between perchlorate levels in rice samples from the Nakdong river watershed and the levels in surface water was estimated to be approximately 0.904 in the 95 % confidence interval. These results show that surface water contamination was highly related to the perchlorate pollution of rice in the Republic of Korea.     

Biomonitoring of polychlorinated biphenyls in Bavaria/Germany—long-term observations and standardization

In the 1980s, it was demonstrated that semi-volatile organic compounds (SVOCs) like polychlorinated biphenyls (PCBs) accumulate in plant leaves. Plants are at the base of the food chain, and therefore a starting point for transfer of PCBs to animals and related human exposure. For two decades, the Environment Agency of the German federal state of Bavaria (LfU) has been operating long-term monitoring stations to measure the impact of organic air pollutants. Standardized ryegrass, curly kale, and spruce needles are used as bioindicators for the atmospheric entries of PCBs into vegetation. From the end of 1990s to 2009, there was a marked decline in the concentrations of indicator PCBs (i-PCBs) and a minor decline in PCB-TEQ levels. After 2009, the concentrations leveled off. In rural areas, the median concentrations of Σ6 i-PCB in ryegrass and curly kale were about 3 and 4 μg/kg dm in 2000, and have been about 0.5 and 1 μg/kg dm since 2009, respectively. Concentrations in spruce needles fell from 0.9 to 0.4 μg/kg dm. Median PCB-TEQ concentrations in the bioindicator plants ranged from 0.05 to 0.23 ng/kg dm between 2002 and 2009 and from 0.15 to 0.05 ng/kg dm after 2009. Indicator PCB and PCB-TEQ concentrations were several times higher at the urban station in Munich than at the rural areas, reflecting the emissions from in-use PCB stocks in the building sector. The likely reason of the slower decrease of PCB-TEQ compared to i-PCBs is the formation of PCB-126 by dechlorination of industrial PCBs in open applications.     

Exposure to carbonyl compounds in charcoal production plants in Bahia, Brazil

Studies have investigated the exposure levels of carbonyl compounds (CC) in the indoor and outdoor air of homes, vehicles, workplaces, urban and industrial areas, and rural sites. However, an investigation of these emissions and occupational exposure to CC in charcoal production facilities has not been previously conducted. The objective of this study was to measure the atmospheric concentrations of several CC to assess the exposure of workers of two charcoal plants located north of Salvador, Bahia, Brazil. Stationary and personal samples were collected using Sep-Pak® C18 cartridges that were coated with a 0.2 % acidic solution of 2,4-dinitrophenylhydrazine. The quantification of the resulting 2,4-dinitrophenylhydrazone derivatives was conducted using a high-performance liquid chromatography system with UV detection. In the personal samples, the concentrations of formaldehyde, acetaldehyde, propanone, furfural, and C4 isomers (n-butanal-isobutanal-butanone) ranged from 12 to 139, 38 to 165, 136 to 483, 39 to 114, and 63 to 132 μg?m^?3, respectively. In the stationary samples, the concentrations of these CC ranged from 20 to 160, 111 to 284, 328 to 644, 70 to 163, and 100 to 176 μg?m^?3, respectively. When compared to the occupational exposure limits for 8 h, the concentrations of formaldehyde were often greater than the levels recommended by the American National Institute for Occupational Safety and Health, which indicates a health risk for charcoal workers. These results are the first reported concerning the occupational exposure to CC in charcoal plants.     

Cancer risk from gaseous carbonyl compounds in indoor environment generated from household coal combustion in Xuanwei,China

Airborne carbonyls were characterized from emitted indoor coal combustion. Samples were collected in Xuanwei (Yunnan Province), a region in China with a high rate of lung cancer. Eleven of 19 types of samples (58%) demonstrated formaldehyde concentrations higher than the World Health Organization exposure limit (a 30-min average of 100 μg m^?3). Different positive significant correlations between glyoxal/methylglyoxal and formaldehyde/acetaldehyde concentrations were observed, suggesting possible different characteristics in emissions between two pairs of carbonyl compounds. A sample in the highest inhalation risk shows 29.2 times higher risk than the lowest sample, suggesting different coal sampling locations could contribute to the variation of inhalation risk. Inhabitants in Xuanwei also tend to spend more time cooking and more days per year indoors than the national average. The calculated cancer risk ranged from 2.2–63 × 10^?5, which shows 13 types of samples at high-risk level. Cumulative effect in combination with different carbonyls could have contributed to the additive actual inhalation cancer risk. There is a need to explicitly address the health effects of environmentally relevant doses, considering life-long exposure in indoor dwellings.     

Removal of xenobiotics from effluent discharge by adsorption on zeolite and expanded clay: an alternative to activated carbon?

Xenobiotics such as pesticides and pharmaceuticals are an increasingly large problem in aquatic environments. A fixed-bed adsorption filter, used as tertiary stage of sewage treatment, could be a solution to decrease xenobiotics concentrations in wastewater treatment plants (WWTPs) effluent. The adsorption efficiency of two mineral adsorbent materials (expanded clay (EC) and zeolite (ZE)), both seen as a possible alternative to activated carbon (AC), was evaluated in batch tests. Experiments involving secondary treated domestic wastewater spiked with a cocktail of ten xenobiotics (eight pharmaceuticals and two pesticides) known to be poorly eliminated in conventional biological process were carried out. Removal efficiencies and partitions coefficients were calculated for two levels of initial xenobiotic concentration, i.e, concentrations lower to 10 μg/L and concentrations ranged from 100 to 1,000 μg/L. While AC was the most efficient adsorbent material, both alternative adsorbent materials showed good adsorption efficiencies for all ten xenobiotics (from 50 to 100 % depending on the xenobiotic/adsorbent material pair). For all the targeted xenobiotics, at lower concentrations, EC presented the best adsorption potential with higher partition coefficients, confirming the results in terms of removal efficiencies. Nevertheless, Zeolite presents virtually the same adsorption potential for both high and low xenobiotics concentrations to be treated. According to this first batch investigation, ZE and EC could be used as alternative absorbent materials to AC in WWTP.     

Presence of microbial and chemical source tracking markers in roof-harvested rainwater and catchment systems for the detection of fecal contamination

Microbial source tracking (MST) and chemical source tracking (CST) markers were utilized to identify fecal contamination in harvested rainwater and gutter debris samples. Throughout the sampling period, Bacteroides HF183 was detected in 57.5 % of the tank water samples and 95 % of the gutter debris samples, while adenovirus was detected in 42.5 and 52.5 % of the tank water and gutter debris samples, respectively. Human adenovirus was then detected at levels ranging from below the detection limit to 316 and 1253 genome copies/μL in the tank water and debris samples, respectively. Results for the CST markers showed that salicylic acid (average 4.62 μg/L) was the most prevalent marker (100 %) in the gutter debris samples, caffeine (average 18.0 μg/L) was the most prevalent in the tank water samples (100 %) and acetaminophen was detected sporadically throughout the study period. Bacteroides HF183 and salicylic acid (95 %) and Bacteroides HF183 and caffeine (80 %) yielded high concurrence frequencies in the gutter debris samples. In addition, the highest concurrence frequency in the tank water samples was observed for Bacteroides HF183 and caffeine (60 %). The current study thus indicates that Bacteroides HF183, salicylic acid and caffeine may potentially be applied as source tracking markers in rainwater catchment systems in order to supplement fecal indicator analyses.     

Importance of fish gender as a factor in environmental monitoring of mercury

Total mercury concentrations were determined in the gonadal tissues of 15 female and 10 male European perch (Perca fluviatilis) from one location of the stream “Jevanský potok” located about 30 km from Prague (Czech Republic). Tissue samples were frozen at ?26 °C in polypropylene containers until further processing, which was carried out using an Advance Mercury Analyser (single purpose atomic absorption spectrometer). Mercury concentrations were present in all analysed gonad samples, and ranged from 2.3 to 12.7 μg/kg wet weight. However, we determined a mean Hg concentration (9.45 μg/kg) in male gonads that was 2.4 times greater than that of female gonads (3.9 μg/kg). This is an important finding when taking into account fish sex in environmental pollution monitoring (especially for mercury contamination).     

Emission rates of chlorinated volatile organics from new and used consumer products found during vapor intrusion investigations: Impact on indoor air concentrations

Consumer products can emit chlorinated volatile organic compounds (CVOCs) that complicate vapor intrusion (VI) assessments. Assessment protocols acknowledge the need to remove these products during VI investigations, but they can be problematic to identify and locate. Predicting if the products cause detectable air concentrations is also difficult since emission rate information is limited and can vary with product use and age. In this study, the emission rates of 1,2-dichloroethane, trichloroethene, tetrachloroethene, and carbon tetrachloride from four consumer products identified as indoor sources during VI field investigations were measured under laboratory conditions using a flow through system. Emissions of PCE from an adhesive container tube ranged from 1.33 ± 1.13 μg/min (unopened) to 23.9 ± 2.93 μg/min (previously opened). The laboratory-measured emission rates were used to estimate indoor air concentrations, which were then compared to concentrations measured after the products placed were into an actual residence. The estimated and measured indoor air concentrations were generally comparable, showing that emission rate information can be used to determine the relative impact of internal CVOC sources.     

Trace metals in Ganges soft-shell turtle (Aspideretes gangeticus) from two barrage: Baloki and Rasul, Pakistan

The concentration of nine metals was measured in liver, kidney, heart, muscle, plastron, and carapace of Aspideretes gangeticus from Rasul and Baloki barrages, Pakistan. The results indicated that metal concentration were significant different among tissues of Ganges soft-shell turtles. However, higher concentrations of Co (5.12 μg/g) and Ni (1.67 μg/g) in liver, Cd (0.41 μg/g) in heart, Fe (267.45 μg/g), Cd (2.12 μg/g) and Mn (2.47 μg/g) in kidney, Cd (0.23 μg/g), Cu (2.57 μg/g), Fe (370.25 μg/g), Mn (5.56 μg/g), and Pb (8.23 μg/g) in muscle of A. gangeticus were recorded at Baloki barrage than Rasul barrage. Whereas mean concentrations of Pb (3.33 μg/g) in liver, Co (1.63 μg/g), Cu (11.32 μg/g), Pb (4.8 μg/g) and Zn (144.69 μg/g) in heart, Co (4.12 μg/g) in muscle, Ni (1.31 μg/g), Pb (2.18 μg/g), and Zn (9.78 μg/g) in carapace were recorded higher at Rasul barrage than Baloki barrage. The metals followed the trend Fe > Zn > Ni > Cu > Mn > Pb > Cr > Co > Cd. Metals of toxicological concern such as Cr, Pb, and Cd were at that level which can cause harmful effects to turtles. The results provide baseline data of heavy metals on freshwater turtle species of Pakistan.     

Evaluating levels and health risk of heavy metals in exposed workers from surgical instrument manufacturing industries of Sialkot,Pakistan

The study aimed to monitor heavy metal (chromium, Cr; cadmium, Cd; nickel, Ni; copper, Cu; lead, Pb; iron, Fe; manganese, Mn; and zinc, Zn) footprints in biological matrices (urine, whole blood, saliva, and hair), as well as in indoor industrial dust samples, and their toxic effects on oxidative stress and health risks in exposed workers. Overall, blood, urine, and saliva samples exhibited significantly higher concentrations of toxic metals in exposed workers (Cr; blood 16.30 μg/L, urine 58.15 μg/L, saliva 5.28 μg/L) than the control samples (Cr; blood 5.48 μg/L, urine 4.47 μg/L, saliva 2.46 μg/L). Indoor industrial dust samples also reported to have elevated heavy metal concentrations, as an example, Cr quantified with concentration of 299 mg/kg of dust, i.e., more than twice the level of Cr in household dust (136 mg/kg). Superoxide dismutase (SOD) level presented significant positive correlation (p?≤?0.01) with Cr, Zn, and Cd (Cr?>?Zn?>?Cd) which is an indication of heavy metal’s associated raised oxidative stress in exposed workers. Elevated average daily intake (ADI) of heavy metals resulted in cumulative hazard quotient (HQ) range of 2.97–18.88 in workers of different surgical units; this is an alarming situation of health risk implications. Principal component analysis-multiple linear regression (PCA-MLR)-based pie charts represent that polishing and cutting sections exhibited highest metal inputs to the biological and environmental matrices than other sources. Heavy metal concentrations in biological matrices and dust samples showed a significant positive correlation between Cr in dust, urine, and saliva samples. Current study will help to generate comprehensive base line data of heavy metal status in biomatrices and dust from scientifically ignored industrial sector. Our findings can play vital role for health departments and industrial environmental management system (EMS) authorities in policy making and implementation.     

Characterization and concentrations of polycyclic aromatic hydrocarbons in emissions from different heating systems in Damascus,Syria

Traffic has long been recognized as the major contributor to polycyclic aromatic hydrocarbon (PAH) emissions to the urban atmosphere. Stationary combustion sources, including residential space heating systems, are also a major contributor to PAH emissions. The aim of this study was to determine the profile and concentration of PAHs in stack flue gas emissions from different kinds of space heaters in order to increase the understanding of the scale of the PAH pollution problem caused by this source. This study set out to first assess the characteristics of PAHs and their corresponding benzo[a]pyrene equivalent emissions from a few types of domestic heaters and central heating systems to the urban atmosphere. The study, enabled for the first time, the characterization of PAHs in stationary combustion sources in the city of Damascus, Syria. Nine different types of heating systems were selected with respect to age, design, and type of fuel burned. The concentrations of 15 individual PAH compounds in the stack flue gas were determined in the extracts of the collected samples using high-performance liquid chromatography system (HPLC) equipped with ultraviolet–visible and fluorescence detectors. In general, older domestic wood stoves caused considerably higher PAH emissions than modern domestic heaters burning diesel oil. The average concentration of ΣPAH (sum of 15 compounds) in emissions from all types of studied heating systems ranged between 43?±?0.4 and 316?±?1.4 μg/m³. Values of total benzo[a]pyrene equivalent ranged between 0.61 and 15.41 μg/m³.     

Nematicidal activity of terpenoids

Thirty four phytoterpenoids were evaluated for their nematicidal effect using the model nematode Caenorhabditis elegans. Nematicidal activities of the tested compounds at concentrations of 50 μg/mL showed wide variation in their effects ranging from no effect, weak, moderate and strong effects. Terpenoids exerting 50% or higher mortality at 50 μg/mL were further tested at five different concentrations to calculate the concentration that will kill 50% of the nematode population (LC₅₀). Among the most effective terpenoids were carvacrol, thymol, nerolidol, α-terpinene, geraniol, citronellol, farnesol, limonene, pseudoionone and eugenol in a descending order. These compounds exhibited a dose-dependent effect. The results suggest that the selected monoterpenoids and essential oils with a high concentration of these compounds mayprovide potential natural nematicides and merit further study as botanical nematicides for the control of both plant and animal parasitic nematodes. In general, oxygenated terpenoids and phenolic terpenoids exhibited higher nematicidal activity than hydrocarbons terpenoids.     

Chemical characteristics of chromophoric dissolved organic matter in rainwater

Proton nuclear magnetic resonance (¹H-NMR), UV absorbance and excitation-emission matrix (EEM) fluorescence spectroscopy were used to define the chemical characteristics of chromophoric dissolved organic matter (CDOM) in whole and C₁₈ extracted rainwater. The average total recovery of fluorescence determined from the sum of extract and filtrate fractions relative to the whole was 86% suggesting that 14% of fluorescent CDOM in rainwater is comprised of very hydrophobic material that cannot be eluted from the column. Half the fluorescence of rainwater was recovered in the filtrate fraction which is important because it suggests that 50% of the chromophoric material present in precipitation is relatively hydrophilic. The average spectral slope coefficient was smaller in extracted samples (16.3 ± 9.0 μm^?1) relative to whole samples (18.9 ± 2.8 μm^?1) suggesting that the extracted material contains larger molecular weight material. Approximately one-third of the total dissolved organic carbon (DOC) in rainwater exists in the extract fraction suggesting that a large percentage of the uncharacterized DOC in rainwater can be accounted for by these hydrophobic macromolecular species. The fluorescence of extracted samples is strongly correlated with total NMR integration and is most sensitive to aromatic protons suggesting that molecules in this region are the most important in controlling the optical properties of rainwater. The lower removal efficiency of CDOM in rainwater relative to surface waters or the water-soluble fraction of aerosols during solid phase extraction (SPE) suggests that rainwater contains significantly more hydrophilic chromophoric compounds which are compositionally different than found in these other aquatic matrices.     

Bioaccumulation and effects of perfluorinated compounds (PFCs) in zebra mussels (Dreissena polymorpha)

Perfluorinated chemicals (PFCs) have been used for many years in numerous industrial products and are known to accumulate in organisms. A recent survey showed that tissue levels of PFCs in aquatic organisms varied among compounds and species being undetected in freshwater zebra mussels Dreissena polymorpha. Here we studied the bioaccumulation kinetics and effects of two major PFCs, perfluorooctane sulfonic acid compound (PFOS) and perfluorooctanoic acid (PFOA), in multixenobiotic transporter activity (MXR) and filtration and oxygen consumption rates in zebra mussel exposed to a range of concentrations of a PCF mixture (1–1,000 μg/L) during 10 days. Results indicate a low potential of the studied PFCs to bioaccumulate in zebra mussel tissues. PFCs altered mussel MXR transporter activity being inhibited at day 1 but not at day 10. Bioaccumulation kinetics of PFCs were inversely related with MXR transporter activity above 9 ng/g wet weight and unrelated at tissue concentration lower than 2 ng/g wet weight suggesting that at high tissue concentrations, these type of compounds may be effluxed out by MXR transporters and as a result have a low potential to be bioaccumulated in zebra mussels. Oxygen consumption rates but not filtering rates were increased in all exposure levels and periods indicating that at environmental relevant concentrations of 1 μg/L, the studied PFCs enhanced oxidative metabolism of mussels. Overall, the results obtained in this study confirm previous findings in the field indicating that an important fraction of PFC accumulated in mussel tissues is eliminated actively by MXR transporters or other processes that are metabolically costly.     

Betulinol and wood sterols in sediments contaminated by pulp and paper mill effluents: dissolution and spatial distribution

The goal was to determine dissolution potency of betulinol and wood sterols (WSs) from pulp and paper mill-contaminated sediments and the current stratification for assessment the load due to potential erosion in the river-like watercourse. Both compounds are wood extractives, which may be toxic to benthos and fish. This research continues a study in which other wood extractives, resin acids and their derivative, retene, were analysed. Sediments were collected from 1, 3.5, 12, 15, and 33 km downstream from the pulp and paper mills, and from 2 upstream reference sites. The dissolution potency into sediment–water elutriates (1?+?4?v/v) was studied by two agitation times and temperatures. The vertical amounts of extractives were determined from the uppermost 20 cm of sediment. The amounts of extractives potentially released were estimated from the sediment layers 0–2 and 2–5 cm by using spatial interpolation. According to the interpolation, the total amount of betulinol and β-sitosterol was calculated as kg/ha in the whole sediment area. Significant concentrations of betulinol (1,666 μg/g, dw) and WSs (2,886 μg/g, dw) were measured from the sediments. According spatial interpolation, the highest calculated amount of betulinol (4,726 kg/ha) and that of the most abundant WS, β-sitosterol (3,571 kg/ha), were in the lake where the effluents were discharged. In the dissolution experiment, the highest concentration of betulinol in sediment (0–10 cm) and elutriate was 412 μg/g (dw) and 165 μg/l, respectively. For WSs, concentrations were 768 μg/g (dw) in sediment and 273 μg/l in elutriate. In a worst-case scenario, betulinol may be desorbed to water in concentrations which are hazardous to aquatic animals. Instead WSs are not a risk in this study area. The amount of desorption varied depending on the concentration of contaminants in sediment, the nature of disturbance, and the sediment organic carbon content.