A four-year phytoremediation trial to decontaminate soil polluted by wood preservatives: phytoextraction of arsenic, chromium, copper, dioxins and furans.

Widely used as wood preservatives for the last century, Pentachlorophenol (PCP) and chromated copper arsenate (CCA) have been shown to leach from treated surfaces and contaminate soil of wood storage sites. We performed a four-year field phytoremediation trial in southern Quebec (Canada) on a site contaminated with PCP and CCA with the following objectives: (1) assess the potential of willow, fescue, alfalfa and Indian mustard to tolerate and translocate CCA and PCP residues in their aerial tissues, (2) investigate the possibility of phytoextraction of dioxins and furans, and (3) test the effect of nitrogen fertilizer on phytoremediation performance. We showed that while nitrogen fertilization increased the chlorophyll content of plants, it did not result in a significantly greater plant biomass. We also showed that plants grown in the presence of PCP/CCA residues were able to translocate and concentrate trace elements in their aerial tissues, but also dioxins and furans (PCDD/F). This suggests that plants grown on sites polluted by PCP might contain dioxins and furans and should be treated as contaminated by these toxic chemicals. Finally, the reduction of soil contaminants at the end of the trial suggests that phytoremediation is a promising approach for decontaminating such sites.

The influence of the Cucurbitaceae on mitigating the phytotoxicity and PCDD/PCDF content of soil amended with sewage sludge.

The study evaluates the impact of sewage sludge on OECD - Organization for Economic Cooperation and Development and vegetable soil phytotoxicity, measured using three test species: Lepidium sativum, Sinapis alba and Sorghum saccharatum, and total and TEQ PCDD/PCDF (toxic equivalency polychlorinated dibenzo-p-dioxins/polychlorinated dibenzofurans) soil concentration, measured using HRGC/HRMS - High Resolution Gas Chromatography/High Resolution Mass Spectrometry. It also evaluates the effect of zucchini and cucumber cultivation during 5-weeks period on mitigating these parameters. The application of 3, 9 and 18 t/ha of sewage sludge gradually increases the phytotoxicity of both OECD and vegetable soil. In the case of OECD soil, the highest roots growth inhibitions were observed for S. alba (73%, 86% and 87%, respectively) and the lowest for S. saccharatum (7%, 59% and 70%), while in vegetable soil inhibitions were averagely 25% lower. Sludge application also led to a 38% (3 t/ha), 169% (9 t/ha) and 506% (18 t/ha) increase in PCDD/PCDF concentration, and the TEQs were augmented by 15%, 159% and 251%. Both soil phytotoxicity and total and TEQ PCDD/PCDF concentrations were diminished as a result of zucchini and cucumber cultivation. The maximum reduction of soil phytotoxicity (83%) was observed as an effect of cucumber cultivation, while zucchini was 11% less effective. Zucchini, in turn, was more efficient in PCDD/PCDF removal (37% reduction), followed by cucumber (24%). Such differences were not observed in the case of TEQ reductions (68% and 66% for zucchini and cucumber cultivation, respectively).

A modified QuEChERS approach for the screening of dioxins and furans in sediments.

A rapid extraction and cleanup method for the screening of polychlorinated dibenzo-p-dioxins and polychlorinated dibenzofurans in sediments is described which combines a modified QuEChERS extraction with carbon reversed-phase solid phase extraction cleanup. This approach is compared to the classical Soxhlet extraction and multi-column cleanup method in terms of toxic equivalence quotients (TEQs), precision, instrumental chromatography, method detection limits (MDLs), recovery of (13)C-labelled quantitation standard, sample preparation time, workload capacity, and sustainability factors. TEQs of 32 sediment samples were found to be well correlated and differed by 16 ± 10 % between the two methods. Certified and standard reference sediments differed by 4.1 and 6.7 %, respectively. Precision and instrumental chromatography were comparable. While the modified QuEChERS method had higher MDLs and lower recoveries, in terms of preparation time and workload capacity, the modified QuEChERS approach can prepare approximately 30 samples per day as compared to 10-20 samples in 3 to 4 days for the classic method. The modified QuEChERS method was also found to be safer and greener. The appreciable improvement in capacity makes the modified QuEChERS approach a suitable alternative to the classical method for applications where turnaround time and the number of samples that can be analyzed are more important than minimal detection limits. Graphical Abstract Created using Microsoft Paint for Windows 7 Professional A bar graph with the structures of dioxins and furans on the x axis shows agreement between two sets of data. A legend labels the first set of data as Soxhlet. The Soxhlet set is illustrated as four days crossed off of a calendar page, a Soxhlet extractor, and several packed chromatography columns. The legend identifies the second set of data as QuEChERS. The QuEChERS set is represented by a clock face marked with twenty four hours, two centrifuge tubes containing the sediment and reagents before and after salting out, and a carbon column attached to a reservoir.

Racial/Ethnic Disparities Among Patients Undergoing Anterior Cervical Discectomy and Fusion or Posterior Cervical Decompression and Fusion for Cervical Spondylotic Myelopathy: A National Administrative Database Analysis.

INTRODUCTION: The aim of this study was to investigate the impact of racial disparities on surgical outcomes for cervical spondylotic myelopathy (CSM). METHODS: Adult patients undergoing anterior cervical discectomy and fusion (ACDF) or posterior cervical decompression and fusion (PCDF) for CSM were identified from the 2016 to 019 National Inpatient Sample Database using the International Classification of Diseases codes. Patients were categorized based on approach (ACDF or PCDF) and race/ethnicity (White, Black, Hispanic). Patient demographics, comorbidities, operative characteristics, adverse events, and health care resource utilization were assessed. Multivariate logistic regression analyses were used to identify independent predictors of extended length of stay (LOS), nonroutine discharge (NRD), and exorbitant costs. RESULTS: A total of 46,500 patients were identified, of which 36,015 (77.5%) were White, 7465 (16.0%) were Black, and 3020 (6.5%) were Hispanic. Black and Hispanic patients had a greater comorbidity burden compared to White patients (P = 0.001) and a greater incidence of any postoperative complication (P = 0.001). Healthcare resource utilization were greater in the PCDF cohort than the ACDF cohort and greater in Black and Hispanic patients compared to White patients (P < 0.001). Black and Hispanic patient race were significantly associated with extended hospital LOS ([Black] odds ratio [OR]: 2.24, P < 0.001; [Hispanic] OR: 1.64, P < 0.001) and NRD ([Black] OR: 2.33, P < 0.001; [Hispanic] OR: 1.49, P = 0.016). Among patients who underwent PCDF, Black race was independently associated with extended hospital LOS ([Black] OR: 1.77, P < 0.001; [Hispanic] OR: 1.47, P = 0.167) and NRD ([Black] OR: 1.82, P < 0.001; [Hispanic] OR: 1.38, P = 0.052). CONCLUSIONS: Our study suggests that patient race may influence patient outcomes and healthcare resource utilization following ACDF or PCDF for CSM.

Alteration of biomass toxicity in torrefaction - A XDS-CALUX bioassay study.

Torrefaction constitutes one of the promising technologies for the management of waste biomass and the production of high-carbon products for combustion, gasification, adsorption of pollutants or soil treatment. Unfortunately, waste biomass may be contaminated with toxic persistent organic pollutants, such as polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/PCDF) and dioxin-like biphenyls (dl-PCB). Literature does not provide consistent measurements on how the low-temperature thermochemical processing, such as torrefaction, affects the toxicity of biomass. This contribution assesses how a torrefaction treatment, conducted at 200 °C, modifies the toxicity due to PCDD/PCDF/dl-PCB in biomass. We deploy the XDS-CALUX biotest on five types of waste biomass (sewage sludge, tree bark, cattle manure, spent coffee ground, common reed), before and after treatment. The content of total dioxin- & biphenyl fraction compounds in the raw biomass, investigated in this study, varies from 0.14 to 3.67 pg BEQ·g-1d.m., and in the torrefied biomass between 0.17 and 6.00 pg BEQ·g-1d.m.; BEQ stands for bioanalytical equivalent. This increase is statistically insignificant at p = 0.05, taking into account all types of examined biomass. This proves that low-temperature torrefaction cannot detoxify biomass, i.e., chars, produced from biomass characterized by elevated concentration of PCDD/PCDF/dl-PCB, will reflect the contamination of the feedstocks. With respect to heavy metals, we conclude that only the content of Cd in biomass, and, to a lesser extent, the abundance of Cu and Fe, modify the toxicity of this material during its thermochemical treatment at low temperature.

Genotoxic and phytotoxic risk assessment of fresh and treated hydrochar from hydrothermal carbonization compared to biochar from pyrolysis.

Biochar is discussed as an option for climate change mitigation via C sequestration and may promote sustainable resource efficiency. Large-scale field trials and commercial business with char materials have already started. Therefore char materials have to be assessed for toxic compounds. We tested genotoxic effects of different hydrochars and biochars with the Tradescantia micronucleus test. For this purpose chromosomal aberrations in pollen cells of Tradescantia in the form of micronuclei were evaluated microscopically after defined exposition to extracts from char materials. Hydrochars from hydrothermal carbonization mostly exhibited significantly negative results. Additional germination experiments with hydrochar showed total germination inhibition at additions above five percent v/v in comparison to biochar. However, biological post-treatment of previously toxic hydrochar was successful and toxic effects were eliminated completely. Some post-treated hydrochars even showed growth stimulating effects. Our results clearly demonstrate the necessity of risk assessment with bioindicators. The chosen tests procedures can contribute to biochar and hydrochar characterization for safe application.

Impact of Preoperative Frailty on Outcomes in Patients with Cervical Spondylotic Myelopathy Undergoing Anterior vs. Posterior Cervical Surgery.

Introduction: Frailty has been shown to negatively influence patient outcomes across many disease processes, including in the cervical spondylotic myelopathy (CSM) population. The aim of this study was to assess the impact that frailty has on patients with CSM who undergo anterior cervical discectomy and fusion (ACDF) or posterior cervical decompression and fusion (PCDF). Materials and Methods: A retrospective cohort study was performed using the 2016-2019 national inpatient sample. Adult patients (≥18 years old) undergoing ACDF only or PCDF only for CSM were identified using ICD codes. The patients were categorized based on receipt of ACDF or PCDF and pre-operative frailty status using the 11-item modified frailty index (mFI-11): pre-Frail (mFI = 1), frail (mFI = 2), or severely frail (mFI ≥ 3). Patient demographics, comorbidities, operative characteristics, perioperative adverse events (AEs), and healthcare resource utilization were assessed. Multivariate logistic regression analyses were used to identify independent predictors of extended length of stay (LOS) and non-routine discharge (NRD). Results: A total of 37,990 patients were identified, of which 16,665 (43.9%) were in the pre-frail cohort, 12,985 (34.2%) were in the frail cohort, and 8340 (22.0%) were in the severely frail cohort. The prevalence of many comorbidities varied significantly between frailty cohorts. Across all three frailty cohorts, the incidence of AEs was greater in patients who underwent PCDF, with dysphagia being significantly more common in patients who underwent ACDF. Additionally, the rate of adverse events significantly increased between ACDF and PCDF with respect to increasing frailty (p < 0.001). Regarding healthcare resource utilization, LOS and rate of NRD were significantly greater in patients who underwent PCDF in all three frailty cohorts, with these metrics increasing with frailty in both ACDF and PCDF cohorts (LOS: p < 0.001); NRD: p < 0.001). On a multivariate analysis of patients who underwent ACDF, frailty and severe frailty were found to be independent predictors of extended LOS [(frail) OR: 1.39, p < 0.001; (severely frail) OR: 2.25, p < 0.001] and NRD [(frail) OR: 1.49, p < 0.001; (severely frail) OR: 2.22, p < 0.001]. Similarly, in patients who underwent PCDF, frailty and severe frailty were found to be independent predictors of extended LOS [(frail) OR: 1.58, p < 0.001; (severely frail) OR: 2.45, p < 0.001] and NRD [(frail) OR: 1.55, p < 0.001; (severely frail) OR: 1.63, p < 0.001]. Conclusions: Our study suggests that preoperative frailty may impact outcomes after surgical treatment for CSM, with more frail patients having greater health care utilization and a higher rate of adverse events. The patients undergoing PCDF ensued increased health care utilization, compared to ACDF, whereas severely frail patients undergoing PCDF tended to have the longest length of stay and highest rate of non-routine discharge. Additional prospective studies are necessary to directly compare ACDF and PCDF in frail patients with CSM.

Can a Novel Natural Language Processing Model and Artificial Intelligence Automatically Generate Billing Codes From Spine Surgical Operative Notes?

STUDY DESIGN: Retrospective cohort. OBJECTIVE: Billing and coding-related administrative tasks are a major source of healthcare expenditure in the United States. We aim to show that a second-iteration Natural Language Processing (NLP) machine learning algorithm, XLNet, can automate the generation of CPT codes from operative notes in ACDF, PCDF, and CDA procedures. METHODS: We collected 922 operative notes from patients who underwent ACDF, PCDF, or CDA from 2015 to 2020 and included CPT codes generated by the billing code department. We trained XLNet, a generalized autoregressive pretraining method, on this dataset and tested its performance by calculating AUROC and AUPRC. RESULTS: The performance of the model approached human accuracy. Trial 1 (ACDF) achieved an AUROC of .82 (range: .48-.93), an AUPRC of .81 (range: .45-.97), and class-by-class accuracy of 77% (range: 34%-91%); trial 2 (PCDF) achieved an AUROC of .83 (.44-.94), an AUPRC of .70 (.45-.96), and class-by-class accuracy of 71% (42%-93%); trial 3 (ACDF and CDA) achieved an AUROC of .95 (.68-.99), an AUPRC of .91 (.56-.98), and class-by-class accuracy of 87% (63%-99%); trial 4 (ACDF, PCDF, CDA) achieved an AUROC of .95 (.76-.99), an AUPRC of .84 (.49-.99), and class-by-class accuracy of 88% (70%-99%). CONCLUSIONS: We show that the XLNet model can be successfully applied to orthopedic surgeon's operative notes to generate CPT billing codes. As NLP models as a whole continue to improve, billing can be greatly augmented with artificial intelligence assisted generation of CPT billing codes which will help minimize error and promote standardization in the process.

Use of the Geriatric Nutritional Risk Index to Assess Risk for Postoperative Complications Following Posterior Cervical Decompression/Fusion.

BACKGROUND: Posterior cervical decompression with or without fusion (PCD/F) is used to manage degenerative spinal conditions. Malnutrition has been implicated for poor outcomes in spine surgery. The aim of this study was to assess the ability of the Geriatric Nutritional Risk Index (GNRI) as a risk calculator for postoperative complications in patients undergoing PCD/F. METHODS: The 2006 to 2018 American College of Surgeons National Surgery Quality Improvement Program Database was queried for patients undergoing PCD/F. Nutritional status was categorized as normal (GNRI greater than 98), moderately malnourished (GNRI 92-98), or severely malnourished (GNRI less than or equal to 92). Complications within 30 days of surgery were compared among the groups. Preoperative data that were statistically significant (P < 0.05) upon univariate χ2 analysis were included in the univariate then multivariate binary regression model to calculate adjusted ORs. All ORs were assessed at the 95% CI. RESULTS: Of the 7597 PCD/F patients identified, 15.6% were severely malnourished and 19.1% were moderately malnourished. Severe and moderate malnourishment were independent risk factors for mortality (OR = 3.790, 95% CI 2.492-5.763, P < 0.001; OR = 2.150, 95% CI 1.351-3.421, P = 0.011). Severe malnourishment was an independent risk factor for sepsis/septic shock (OR = 3.448, 95% CI 2.402-4.948, P < 0.001). CONCLUSIONS: In elderly patients undergoing PCD/F, severe malnutrition, as defined by the GNRI, was an independent risk factor for mortality and sepsis/septic shock. CLINICAL RELEVANCE: The GNRI may be more useful than other indices for risk stratification in elderly patients because it accounts for confounding variables such as hydration status and paradoxical malnourishment in obese patients.

The Impact of American Society of Anesthesiologists Status on Cost of Care and Length of Stay Following Posterior Cervical Decompression and Fusion.

BACKGROUND: Increased posterior cervical decompression and fusion (PCDF) procedures over the past decade have raised the prospect of bundled payment plans. The American Society of Anesthesiologists (ASA) Physical Status Classification system may enable accurate estimation of health care costs, length of stay (LOS), and other postoperative outcomes in patients undergoing PCDF. METHODS: Low (I and II) versus high (III and IV) ASA class was used to evaluate 971 patients who underwent PCDF between 2008 and 2016 at a single institution. Demographics were compared using univariate analysis. Cost of care, LOS, and postoperative complications were compared using multivariable logistic and linear regression, controlling for sex, age, length of surgery, and number of segments fused. RESULTS: The high ASA class cohort was older (mean age 62 years vs. 55 years, P < 0.0001) and had higher Elixhauser comorbidity index scores (P < 0.0001). ASA class was independently associated with longer LOS (2.1 days, 95% confidence interval [CI] 1.3-2.9, P < 0.0001) and higher cost ($2936, 95% CI $1457-$4415, P < 0.0001). Patients with high ASA class were more likely to have a nonhome discharge (3.9, 95% CI 2.8-5.6, P < 0.0001), delayed extubation (3.2, 95% CI 1.4-7.3, P = 0.006), intensive care unit stay (2.4, 95% CI 1.5 3.7, P = 0.0001), in-hospital complications (1.5, 95% CI 1.0-2.2, P = 0.03), and 30-day (3.2, 95% CI 1.5-6.8, P = 0.003) and 90-day (3.2, 95% CI 1.8-5.7, P = 0.0001) readmission. CONCLUSIONS: High ASA class is strongly associated with increased costs, LOS, and adverse outcomes following PCDF and could be useful for preoperative prediction of these outcomes.

Anterior vs Posterior Approach in Multilevel Cervical Spondylotic Myelopathy: A Nationwide Propensity-Matched Analysis of Complications, Outcomes, and Narcotic Use.

BACKGROUND: There is unclear evidence regarding the optimal surgical approach for multilevel cervical spondylotic myelopathy (CSM). The objective of this study was to compare complications, outcomes, and narcotic use in anterior discectomy and fusion (ACDF) vs posterior decompression and fusion (PCDF) in CSM patients. STUDY DESIGN: Registry-based retrospective cohort analysis. METHODS: Patients undergoing 3-level ACDF or PCDF for CSM between 2007 and 2017 were identified from the Humana Claims Database using relevant procedure codes. Propensity score-matched groups were compared in regards to complications, outcomes, and narcotic use. RESULTS: Propensity score matching generated equal cohorts of 6124 patients. The posterior fusion group had a higher rate of urinary tract infection (OR 2.47, P < 0.0001), deep vein thrombosis (OR 1.90, P < 0.0001), and pulmonary embolism (OR 1.75, P < 0.0001). In regards to 30-day outcomes, the posterior approach demonstrated higher rates of stroke (OR 1.68, P < 0.0001), wound dehiscence (OR 5.59, P < 0.0001), Surgical site infection (SSI) (OR 4.76, P < 0.0001), wound revision surgery (OR 3.02, P < 0.0001), and all-cause readmission (OR 2.01, P < 0.0001). One-year outcomes revealed higher rates of pseudarthrosis (4.7% vs 2.0%, OR 2.43, P < 0.0001) and revision or extension surgery (OR 2.33, P < 0.0001) in the posterior fusion cohort. These patients also demonstrated significantly higher mean morphine milligram equivalent used at 30 days (OR 1.19, P < 0.0001), as well as 60 (OR 1.20, P < 0.0001), 90 (OR 1.21, P < 0.0001), and 120 (OR 1.21, P < 0.0001) days. CONCLUSIONS: This nationwide propensity-matched analysis of multilevel CSM patients found the posterior approach to be associated with increased rates of inpatient complications, wound complications, 30-day readmission, 1-year pseudarthrosis, and 1-year revision or extension surgery. These patients also demonstrated higher levels of narcotic use up to 120 days after surgery. CLINICAL RELEVANCE: The posterior approach for treatment of CSM may be associated with increased rates of short- and long-term complications in addition to increased narcotic consumption in comparison to the anterior approach.

A retrospective study on dioxins and dioxin-like polychlorinated biphenyls in milk and dairy products from the Latium region (Italy) over a 7-year study period (2011-2017).

This study reports the data of polychlorinated dibenzo-p-dioxins (PCDDs), -furans (PCDFs), and polychlorinated biphenyls dioxin-like (dl PCBs) measured in a total of 260 samples of the dairy supply chain collected over a period of 7 years (2011-2017) in the Latium region (Italy). Levels and average profiles of congeners were reported for each group of the analyzed dairy matrices, and any differences between different sampling strategies were considered (around likely pollutant sources or casual sampling). Of the samples, 95.4% resulted compliant with the regulated levels; only samples belonging to the "sheep bulk milk" matrix were found to be above either the action levels or the maximum levels (tot. 12 samples). Raw milk of the sheep species showed the highest averages (PCDD/F 0.248 and dl PCB 0.966 WHO TEQ pg/g of fat) compared to the milk of other species. The buffalo milk showed a content of dl PCB significantly lower (dl PCB: 0.371 WHO TEQ pg/g of fat) than the sheep milk (p<0.05). Dioxins were found to be superior to furans in almost all dairy products, except in the noncompliant samples where furans were higher. The OCDD was found to be the most abundant congener in almost all dairy products. This study provides a first list of reference values for background contamination of the dairy supply chain in the Latium region. These pre-existing values will be useful in all cases of environmental pollution to identify critical situations.

Hypoglossal nerve injury with C1 lateral mass screw placement: A case report and review of the literature.

We report the case of a 62-year-old man who presented with a progressive myelopathy secondary to spinal cord compression from an odontoid process fracture and subaxial central canal stenosis. The patient underwent a C1-T2 posterior decompression and instrumented fusion (PCDF) and did well immediately postoperatively. However, on POD1, he developed a right hypoglossal nerve (HN) palsy attributed to direct mechanical compression or injury from the C1 lateral mass screw (LMS), which improved following a revision and screw replacement. While HN injury is a known complication of high anterior and anterolateral cervical spine approaches as well as transcondylar screw fixation, this case aims to expand on the limited reports available regarding hypoglossal nerve injury following placement of bicortical C1 LMS. Furthermore, the use of fluoroscopic guidance in addition to anatomic landmarks and triggered electromyography of the tongue are offered as potential solutions to prevent HN injury intraoperatively.

Emissions of dioxins and furans during steam gasification of Automotive Shredder residue; experiences from the Chalmers 2-4-MW indirect gasifier.

Emissions of dioxins and furans during the gasification of Automotive Shredder Residue (ASR) were investigated. The experimental work was carried out in a Dual Fluidized Bed (DFB) system, which consists of a 2-4-MWth gasifier that is fluidized with steam, and an interconnected fluidized bed combustor that is fluidized with air. Two different ASR fractions with higher and lower contents of plastic were tested. Measurements were carried out in the flue gas stream exiting the combustion side of the DFB, as well as in the raw gas stream exiting the gasifier side. A calcium (lime) coat was applied to the flue gas filter to ensure compliance with the emissions regulations regarding the retention of HCl and dioxins. The results showed lower emissions of polychlorinated dibenzo-p-dioxins/dibenzofurans (PCDD/PCDF) in the flue gas when the raw gas derived from the ASR gasification was combusted, as compared to the direct combustion of ASR. The level of polychlorinated compounds in the flue gas before the lime-coated filter was 0.11 ng/m3N dry gas (I-TEQ) when gasification was used as a pre-step, as compared to 0.27 ng/m3N dry gas (I-TEQ) when the ASR was directly combusted. The raw gas produced by gasification contained very low levels of PCDD/PCDF, whereby the toxicity per kg of ASR was 0.17 ng/kgASR, as compared to 3.44 ng/kgASR after passage through the combustion and cooling sections and 0.34 ng/kgASR at the outlet after the lime-coated filter. A higher content of plastic in the ASR led to an increase in the levels of dioxins and furans in the raw gas, with the highest yield seen for highly chlorinated compounds, while higher temperature in the gasifier is shown to be beneficial in reducing dioxin formation.

Thermochemical formation of dioxins promoted by chromium chloride: In situ Cr- and Cl-XAFS analysis.

Chromium is commonly found in the flue gases and ashes of Municipal Solid Waste Incineration. It has been reported as an active catalyst for the formation of polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/F) during de novo tests, yet its specific mode of action has remained unclear. This study aims to identify the effects of chromium chloride on the formation of PCDD/F and other chloro-aromatics and to elucidate the underlying reaction mechanisms. A series of de novo tests, conducted over a wide range of temperature (from 250 to 550 °C) and for four different oxygen contents (0, 5, 10, 20 %), confirmed the promoting effect of CrCl3 on the PCDD/F formation. In situ X-ray Absorption Fine Structure (XAFS) spectroscopy was applied to investigate the behavior of CrCl3 during heating, describing the entire picture of CrCl3-promoted formation pathways of dioxins. The effect of oxygen was studied by measuring XAFS spectra on samples heated at different oxygen concentrations. According to these spectra, chromium compounds play two key roles during dioxins formation: (a) chlorinating carbon, using chlorine derived from conversion of CrCl3 into Cr2O3, and further oxidation to Cr(VI), and (b) facilitating oxidative destruction of the carbon matrix, while reducing Cr(VI) to Cr2O3.

Spatial and temporal trends of PCDD/Fs in sediment and bivalves along the Korean coasts during 2001-2012.

Concentrations of polychlorinated dibenzo-para-dioxins and dibenzofurans (PCDD/Fs) were measured in sediment and bivalves at 25 locations along the Korean coasts during 2001-2012. Concentrations of PCDD/Fs in sediment and bivalves ranged from 0.15 to 18.9 pg TEQ/g dry weight and from 0.06 to 7.70 pg TEQ/g wet weight, respectively. Elevated PCDD/F concentrations were found at locations close to largest industrial complexes and commercial harbors. A significant decreasing trend of PCDD/Fs in sediment was associated with strong regulation of PCDD/Fs, whereas levels in bivalves did not show a decreasing trend. Octachlorinated dibenzo-p-dioxin (OCDD) was predominant in sediment, while tetrachlorinated dibenzofuran and OCDD were predominant in bivalves. Almost half (46%) of sediment samples exceeded the threshold effect level suggested by the US National Oceanic and Atmospheric Administration, implying ecotoxicological risks to benthic organisms. Our findings support the effectiveness of legislative action on PCDD/Fs for coastal environments of Korea.

Mechanochemical degradation of PCDD/Fs in fly ash within different milling systems.

Two distinct mechanochemical degradation (MCD) methods are adopted to eliminate the polychlorinated dibenzo-p-dioxins and -furans (PCDD/Fs) from fly ash in municipal solid waste incinerators. First, experiments are conducted in a planetary ball mill for selecting suitable additives, and an additive system of SiO2-Al is chosen for its high-efficiency, low-price, and good practicability. The I-TEQ value of PCDD/Fs in washed fly ash decreases dramatically from 6.75 to 0.64 ng I-TEQ/g, after 14 h of milling with 10 wt % SiO2-Al, and dechlorination is identified as the major degradation pathway. Then, this additive is applied in a horizontal ball mill, and the results indicate that the degradation of PCDD/Fs follows the kinetic model established in planetary ball mills. However, longer milling time is required for the same supplied-energy because of the lower energy density of horizontal ball mills, resulting in partial loss of Al reactivity and a lower degradation efficiency of PCDD/Fs. During MCD, the evolution of PCDD/F-signatures is analogous, indicating a similar acting mechanism of all additives in both the two milling systems. Finally, a major dechlorination pathway of PCDD-congeners is proposed based on the signature analysis of congeners synthesized from chlorophenols.

Long-term monitoring programme of polychlorinated dioxins and polychlorinated furans in ambient air of Catalonia, Spain (1994-2015).

Reductions in concentrations of persistent organic pollutants were observed for polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs) in a comparison of two consecutive decades ending in December 31, 2015 (n = 413) and compiled from a 48-station long-term air-monitoring network in Catalonia, Spain. Reductions were observed in geometric mean concentration of total PCDD/Fs, decreasing at a rate of 11% yr-1. Results reflect the relative success of improved pollution control measures at industry and traffic locations. At traffic and industrial locations, PCDD/Fs were reduced by around 68% (from 70 to 22 fg I-TEQ/m3) and 66% (from 57 to 19 fg I-TEQ/m3), respectively. The highest concentration of 1196 fg I-TEQ/m3 was observed during the first decade at an industrial location. The highest concentration over the second decade was at a background location during winter (674 fg I-TEQ/m3). Winter observations are generally higher than those recorded in summer, as evident in an 8-year period of moderate PCDD/F levels (<250 fg I-TEQ/m3, n = 143). PCDD/F congener profiles were identified has having less chlorinated PCDD/F, indicating the presence of nearby combustion sources at selected locations. More long-term sampling campaigns, combined with network optimization and integration into a meteorological model, can offer a tool for future PCDD/Fs control measures in not only Catalonia - but also applicable to other areas.

Iron chloride catalysed PCDD/F-formation: Experiments and PCDD/F-signatures.

Iron chloride is often cited as catalyst of PCDD/F-formation, together with copper chloride. Conversely, iron chloride catalysis has been less studied during de novo tests. This paper presents such de novo test data, derived from model fly ash incorporating iron (III) chloride and established over a vast range of temperature and oxygen concentration in the gas phase. Both PCDD/F-output and its signature are extensively characterised, including homologue and congener profiles. For the first time, a complete isomer-specific analysis is systematically established, for all samples. Special attention is paid to the chlorophenols route PCDD/F, to the 2,3,7,8-substituted congeners, and to their relationship and antagonism.

Formation pathways of PCDD/Fs during the Co-combustion of municipal solid waste and coal.

The co-combustion of simulated municipal solid waste (SMSW) and the coal in a drop-tube furnace is studied in five test cases. The concentration and signature evolution of polychlorinated dibenzo-p-dioxins (PCDD) and -furans (PCDF) in both flue gases and fly ashes are monitored at the level of individual congeners, using statistical methods. Special attention is paid to chlorophenol (CP)-route congeners, 2,3,7,8-substitution, and 1,9-substitution, to reveal the formation pathways of PCDD/Fs and the interaction between SMSW and coal. It is identified that the increase of SMSW proportion alters the major formation pathways from CP-route to chlorophenols/chlorobenzenes condensation and de novo synthesis. The coal-induced carbon enhances the adsorption capacity of fly ash particles for PCDD/Fs, yet facilitates the generation of carbon matrixes and polycyclic aromatic hydrocarbons, both of which will significantly boost the de novo synthesis with the increase of SMSW-induced chlorine and catalytic metals. Further investigations about restricting the participation of chlorine in PCDD/Fs synthesis are essential to increase the treatment capacity of MSW and to reduce the PCDD/Fs emission.