Emission characteristic of polychlorinated dibenzo-p-dioxins and polychlorinated dibenzofurans (PCDD/Fs) from 12 medical waste incinerators (MWIs) which have a total yearly capacity of 523 440 ton medical waste and accounted for 8.1% of total yearly capacity of 246 MWIs in China were studied. The congeners profile, emissions and toxic equivalent concentrations (TEQ) indicators of PCDD/Fs in stack gas from two groups of MWIs were researched, and the possible formation mechanisms of PCDD/Fs from MWIs were preliminarily discussed. The results of present study were summarized as follows. (1) The total concentrations and TEQ of PCDD/Fs in stack gas from MWIs were 0.516–122.803 ng Nm−3 and 0.031–3.463 ng I-TEQ Nm−3, respectively. (2) 1,2,3,4,6,7,8-H7CDF, O8CDD, O8CDF and 1,2,3,4,6,7,8-H7CDD were the indicatory PCDD/Fs of MWI source, which could be used to apportion the sources of PCDD/Fs in environmental medium in China. (3) The emission factors of PCDD/Fs from MWIs ranged from 32.7 to 4900.0 ng I-TEQ ton−1 with a mean of 1923.6 ng I-TEQ ton−1. (4) The gas emissions of PCDD/Fs from researched 12 MWIs and all of MWIs in China in 2016 were 37.742 and 465.951 mg I-TEQ year−1, respectively. (5) 1,2,3,7,8,9-H6CDF and 1,2,3,4,7,8-H6CDF were effective TEQ indicators for the real-time monitoring of the PCDD/Fs emission. (6) The congeners profile and factor composition of PCDD/Fs in stack gas from two groups of MWIs were researched based on positive matrix factorization (PMF) model, and the possible formation mechanisms of PCDD/Fs from MWIs were preliminarily discussed.

This study investigated the potential use of elemental S (S0) to convert Cr-VI to Cr-III which should decrease the bio-availability hence, toxicity of Cr-VI in soils. The bio-available fraction of Cr in soil was measured by phosphate buffer extraction (PBE) and the results showed that the fraction is about 10% of the total Cr-VI and varied from 12.8 to 42.5 mg kg−1. The addition of 4.0 mg g−1 S0 decreased PBE Cr-VI to <0.4 mg kg−1 limit established for Cr-VI toxicity in soils. Synchrotron-based X-ray absorption near-edge structure (XANES), X-ray fluorescence (XRF) and micro-XRD revealed that Cr-III was the dominant species (99% of total Cr) and Cr was retained by hematite and goethite in soil. Fe-containing minerals may have provided sufficient protection to render the dominant Cr-III species biochemically inert to redox processes in soils. It is concluded that S0amendment is a promising approach to remediate Cr-VI contaminated soils.

Microbial transformation of polyfluoroalkyl phosphate esters (PAPs) into perfluorocarboxylic acids (PFCAs) has recently been confirmed to occur in activated sludge and soil. However, there lacks quantitative information about the half-lives of the PAPs and their significance as the precursors to PFCAs. In the present study, the biotransformation of 6:2 and 8:2 diPAP in aerobic soil was investigated in semi-dynamics reactors using improved sample preparation methods. To develop an efficient extraction method for PAPs, six different extraction solvents were compared, and the phenomenon of solvent-enhanced hydrolysis was investigated. It was found that adding acetic acid could enhance the recoveries of the diPAPs and inhibit undesirable hydrolysis during solvent extraction of soil. However 6:2 and 8:2 monoPAPs, which are the first breakdown products from diPAPs, were found to be unstable in the six solvents tested and quickly hydrolyzed to form fluorotelomer alcohols. Therefore reliable measurement of the monoPAPs from a live soil was not achievable. The apparent DT50 values of 6:2 diPAP and 8:2 diPAP biotransformation were estimated to be 12 and > 1000 days, respectively, using a double first-order in parallel model. At the end of incubation of day 112, the major degradation products of 6:2 diPAP were 5:3 fluorotelomer carboxylic acid (5:3 acid, 9.3% by mole), perfluoropentanoic acid (PFPeA, 6.4%) and perfluorohexanoic acid (PFHxA, 6.0%). The primary product of 8:2 diPAP was perfluorooctanoic acid (PFOA, 2.1%). The approximately linear relationship between the half-lives of eleven polyfluoroalkyl and perfluoroalkyl substances (PFASs, including 6:2 and 8:2 diPAPs) that biotransform in aerobic soils and their molecular weights suggested that the molecular weight is a good indicator of the general stability of low-molecular-weight PFAS-based compounds in aerobic soils.

In situ assays based on feeding depression can be powerful ecotoxicological tools that can link physiological organism-level responses to population and/or community-level effects. Amphipods are traditional target species for toxicity tests due to their high sensitivity to contaminants, availability in the field and ease of handling. However, cost-effective in situ assays based on feeding depression are not yet available for amphipods that inhabit estuarine ecosystems. The aim of this work was to assess a short-term in situ assay based on postexposure feeding rates on easily quantifiable food items with an estuarine amphipod.Experiments were carried out under laboratory conditions using juvenile Echinogammarus marinus as the target individual. When 60 Artemia franciscana nauplii (as prey) were provided per individual for a period of 30 min in dark conditions, feeding rates could be easily quantified. As an endpoint, postexposure feeding inhibition in E. marinus was more sensitive to cadmium contamination than mortality. Assay calibration under field conditions demonstrated the relevance of sediment particle size in explaining individual feeding rates in uncontaminated water bodies. An evaluation of the 48-h in situ bioassay based on postexposure feeding rates indicated that it is able to discriminate between unpolluted and polluted estuarine sites. Using the harmonized protocol described here, the in situ postexposure feeding assay with E. marinus was found to be a potentially useful, cost-effective tool for assessing estuarine sediment and water quality.

Black carbon (BC) and PM2.5 were studied for nine years from 2005 to 2013 in the Beijing urban area. The overall weekly average mass concentrations of BC and PM2.5 were 4.3 and 66.8 μg/m³. PM2.5 annual means of the nine years are around 2 times of the standard (GB3095-2012) in China, and are 5–7 times higher than the WHO standard. The Beijing Olympic Games in 2008 was a milestone to mitigate aerosol pollution. Temporal distribution of BC shows a distinct declining trend, and annual mean mass concentrations of PM2.5 after 2008 were lower than those before 2008 but increased from 2011 to 2013. Wind rose plots show that high BC concentrations are usually associated with low wind speed of northeastern or southwestern winds, generally causing poor visibility. Governmental mitigation measures such as traffic restriction despite increased motor vehicle numbers and gasoline consumption and industry relocation with declining consumption of coal and coke were successful in reducing BC emissions. Annual mean of BC was reduced by 38% in 2013 compared to 2005. However, BC contamination in Beijing is still severe when compared to other urban areas around the world.

Benzotriazole UV stabilizers (BUVSs) are widely applied in plastics to prevent discoloration and to enhance product stability. This study describes for the first time the occurrence of nine different lipophilic BUVSs (UV-326, UV-320, UV-329, UV-350, UV-328, UV-327, UV-928, UV-234 and UV-360) in sediment, suspended particulate matter (SPM) and bream liver samples of German rivers. All investigated BUVSs were detected in sediments and SPM at concentrations in the low ng/g dry weight (dw) range. The so far rarely analyzed compound UV-360 as well as UV-326 were the predominant BUVSs in sediments and SPM from the river Rhine reaching maximum concentrations of 62 and 44 ng/g dw, respectively. Five BUVSs were also confirmed to bioaccumulate in bream liver, but neither UV-360 nor UV-326 was detected above the limit of quantification (LOQ). In contrast, highest concentrations in bream liver were determined for UV-327 (65 ng/g dw) and UV-328 (40 ng/g dw).A retrospective time trend analysis of BUVSs in SPM from two sites (river Rhine, 2005 to 2013; river Saar, 2006 to 2013) revealed increasing contamination levels of UV-329 and decreasing levels of UV-320 and UV-350. At one site (river Rhine) time trends of BUVS concentrations were also investigated in bream liver (1995–2013) and supported a considerably reduced exposure to UV-350.A first assessment of the environmental fate of BUVSs by sediment-water batch systems revealed a rapid partitioning into the sediment and no considerable degradation within 100 d.

Atmospheric polycyclic aromatic hydrocarbons (PAHs) and their derivatives are of great concern due to their adverse health effects. However, source identification and apportionment of these compounds, particularly their nitrated and hydroxylated derivatives (i.e., NPAHs and OHPAHs), in fine particulate matter (PM2.5) in Hong Kong are still lacking. In this study, we conducted a 1-year observation at an urban site in Hong Kong. PM2.5-bound PAHs and their derivatives were measured, with median concentrations of 4590, 44.4 and 31.6 pg m−3 for ∑21PAHs, ∑13NPAHs, and ∑12OHPAHs, respectively. Higher levels were observed on regional pollution days than on long regional transport (LRT) or local emission days. Based on positive matrix factorization analysis, four sources were determined: marine vessels, vehicle emissions, biomass burning, and a mixed source of coal combustion and NPAHs secondary formation. Coal combustion and biomass burning were the major sources of PAHs, contributing over 85% of PAHs on regional and LRT days. Biomass burning was the predominant source of OHPAHs throughout the year, while NPAHs mainly originated from secondary formation and fuel combustion. For benzo[a]pyrene (BaP)-based PM2.5 toxicity, the mixed source of coal combustion and NPAHs secondary formation was the major contributor, followed by biomass burning and vehicle emissions.

Ultra-fine-ZnO showed low toxicity in complex water matrix containing multiple components such as PBS buffer and the toxic mechanism of ultra-fine-ZnO has not been clearly elucidated. In present study, enhanced antibacterial activity of 200 nm diameter ultra-fine-ZnO in PBS buffer against Bacillus cereus and Escherichia coli were observed in the presence of several organic acids in comparison with ultra-fine-ZnO in PBS buffer alone. These findings indicated that the toxic effects of the ultra-fine-ZnO was dependent on the concentration of released Zn2+ which was affected by organic acids. The production of reactive oxygen species (ROS) did not responsible to the toxic mechanism of ultra-fine-ZnO which was tested using the antioxidant N-Acetylcysteine (NAC). Indeed, ultra-fine-ZnO induced bacteria cell membrane leakages and cell morphology damages that eventually led to cell death, which were confirmed using propidium monoazide (PMA) in combination with PCR and scanning electron microscopy (SEM). All data gathered herein suggested that released Zn2+ played a major role in the microbial toxicity of ultra-fine-ZnO.

Microcystin-LR (MCLR) is a commonly acting potent hepatotoxin and has been pointed out of potentially causing developmental neurotoxicity, but the exact mechanism is little known. In this study, zebrafish embryos were exposed to 0, 0.8, 1.6 or 3.2 mg/L MCLR for 120 h. MCLR exposure through submersion caused serious hatching delay and body length decrease. The content of MCLR in zebrafish larvae was analyzed and the results demonstrated that MCLR can accumulate in zebrafish larvae. The locomotor speed of zebrafish larvae was decreased. Furthermore, the dopamine and acetylcholine (ACh) content were detected to be significantly decreased in MCLR exposure groups. And the acetylcholinesterase (AChE) activity was significantly increased after exposure to 1.6 and 3.2 mg/L MCLR. The transcription pattern of manf, chrnα7 and ache gene was consistent with the change of the dopamine content, ACh content and AChE activity. Gene expression involved in the development of neurons was also measured. ɑ1-tubulin and shha gene expression were down-regulated, whereas mbp and gap43 gene expression were observed to be significantly up-regulated upon exposure to MCLR. The above results indicated that MCLR-induced developmental toxicity might attribute to the disorder of cholinergic system, dopaminergic signaling, and the development of neurons.

This study was aimed at investigating the detachment of fullerene nC60 nanoparticles (NPs) in saturated sand porous media under transient and static conditions. The nC60 NPs were first attached at primary minima of Derjaguin–Landau–Verwey–Overbeek (DLVO) interaction energy profiles in electrolyte solutions with different ionic strengths (ISs). The columns were then eluted with deionized water to initiate nC60 NP detachment by decreasing solution IS. Finally, the flow of the columns was periodically interrupted to investigate nC60 NP detachment under static condition. Our results show that the detachment of nC60 NPs occurred under both transient and static conditions. The detachment under transient conditions was attributed to the fact that the attractions acting on the nC60 NPs at primary minima were weakened by nanoscale physical heterogeneities and overcome by hydrodynamic drags at lower ISs. However, a fraction of nC60 NPs remained at shallow primary minima in low flow regions, and detached via Brownian diffusion during flow interruptions. Greater detachment of nC60 NPs occurred under both transient and static conditions if the NPs were initially retained in electrolyte solutions with lower valent cations due to lower attractions between the NPs and collectors. Decrease in collector surface chemical heterogeneities and addition of dissolved organic matter also increased the extent of detachment by increasing electrostatic and steric repulsions, respectively. While particle attachment in and subsequent detachment from secondary minima occur in the same electrolyte solution, our results indicate that perturbation in solution chemistry is necessary to lower the primary minimum depths to initiate spontaneous detachment from the primary minima. These findings have important implications for predicting the fate and transport of nC60 NPs in subsurface environments during multiple rainfall events and accordingly for accurately assessing their environmental risks.