Publications by authors named "Daniel S Alessi"

67 Publications

Special issue on contamination, remediation and health for pollutants in natural aquatic, soil, sediments and atmospheric environments.

Environ Geochem Health 2021 Jul 24. Epub 2021 Jul 24.

Department of Environment and Energy, Sejong University, Seoul, 05006, Republic of Korea.

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http://dx.doi.org/10.1007/s10653-021-01043-5DOI Listing
July 2021

Lead (Pb) sorption to hydrophobic and hydrophilic zeolites in the presence and absence of MTBE.

J Hazard Mater 2021 Jun 29;420:126528. Epub 2021 Jun 29.

Department of Engineering, University of Cambridge, Cambridge CB2 1PZ, United Kingdom.

The co-contamination of the environment by metals and organic pollutants is a significant concern, and one such example is lead (Pb) and methyl tert-butyl ether (MTBE) due to their historic use as fuel additives. Clinoptilolite is an abundant and efficient zeolite for metal removal, but the potential interference of co-existing organic pollutants on metal removal, such as MTBE, have rarely been discussed. In this study, a combination of batch sorption tests and synchrotron-based X-ray absorption spectroscopic analyses were employed to investigate Pb sorption mechanism(s) onto clinoptilolite in the presence and absence of MTBE. A comparison was made to synthetic ZSM-5 zeolite to gain insights into differences in Pb binding mechanisms between hydrophilic (clinoptilolite) and hydrophobic (ZSM-5) zeolites. Site occupancy and surface precipitation contributed equally to Pb removal by clinoptilolite, while surface precipitation was the main Pb removal mechanism for ZSM-5 followed by site occupancy. Despite the negligible effect of 100 mg/L MTBE on observed Pb removal from solution by both zeolites, a surface-embedded Pb removal mechanism, through the Mg site on clinoptilolite surface, arises when MTBE is present. This study provides an understanding of atomic-level Pb uptake mechanisms on zeolites, with and without co-contaminating MTBE, which aids in their application in water treatment at co-contaminated sites.
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http://dx.doi.org/10.1016/j.jhazmat.2021.126528DOI Listing
June 2021

Suspended solids-associated toxicity of hydraulic fracturing flowback and produced water on early life stages of zebrafish (Danio rerio).

Environ Pollut 2021 Jun 18;287:117614. Epub 2021 Jun 18.

School of Energy and Environment and State Key Laboratory of Marine Pollution, City University of Hong Kong, Hong Kong, China; Department of Biological Sciences, University of Alberta, Edmonton, Alberta, T6G 2E9, Canada; Hong Kong Branch of Southern Marine Science and Engineering Guangdong Laboratory (Guangzhou), Hong Kong, China. Electronic address:

Hydraulic fracturing flowback and produced water (HF-FPW), which contains polyaromatic hydrocarbons (PAHs) and numerous other potential contaminants, is a complex wastewater produced during the recovery of tight hydrocarbon resources. Previous studies on HF-FPW have demonstrated various toxicological responses of aquatic organisms as consequences of combined exposure to high salinity, dissolved organic compounds and particle/suspended solids-bound pollutants. Noteworthy is the lack of studies illustrating the potentially toxic effects of the FPW suspended solids (FPW-SS). In this study, we investigated the acute and sublethal toxicity of suspended solids filtered from six authentic FPW sample collected from two fracturing wells, using a sediment contact assay based on early-life stages of zebrafish (Danio rerio). PAHs profiles and acute toxicity tests provided initial information on the toxic potency of the six samples. Upon exposure to sediment mixture at two selected doses (1.6 and 3.1 mg/mL), results showed adverse effects in larval zebrafish, as revealed by increased Ethoxyresorufin-O-deethylase (EROD) activity. Transcriptional alterations were also observed in xenobiotic biotransformation (ahr, pxr, cyp1a, cyp1b1, cyp1c1, cyp1c2, cyp3a65, udpgt1a1, udpgt5g1), antioxidant response (sod1, sod2, gpx1a, gpx1b) and hormone receptor signaling (esr1, esr2a, cyp19a1a, vtg1) genes. The results demonstrated that even separated from the complex aqueous FPW mixture, FPW-SS can induce toxicological responses in aquatic organisms' early life stages. Since FPW-SS could sediment to the bottom of natural wetland acting as a continuous source of contaminants, the current findings imply the likelihood of long-term environmental risks of polluted sediments on aquatic ecosystems due to FPW spills.
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http://dx.doi.org/10.1016/j.envpol.2021.117614DOI Listing
June 2021

Modification of ordered mesoporous carbon for removal of environmental contaminants from aqueous phase: A review.

J Hazard Mater 2021 May 30;418:126266. Epub 2021 May 30.

College of Environmental Science and Engineering, Yangzhou University, Yangzhou 225127, China; Joint International Research Laboratory of Agriculture and Agri-Product Safety of Ministry of Education of China, Yangzhou University, Yangzhou 225127, Jiangsu, China; Jiangsu Collaborative Innovation Center for Solid Organic Waste Resource Utilization, China. Electronic address:

Contamination of water bodies by potentially toxic elements and organic pollutants has aroused extensive concerns worldwide. Thus it is significant to develop effective adsorbents for removing these contaminants. As a new member of carbonaceous material families (activated carbon, biochar, and graphene), ordered mesoporous carbon (OMC) with larger specific surface area, ordered pore structure, and higher pore volume are being evaluated for their use in contaminant removal. In this paper, modification techniques of OMC were systematically reviewed for the first time. These include nonmetallic doping modification (nitrogen, sulfur, and boron) and the impregnation of nano-metals and metal oxides (iron, copper, cobalt, nickel, magnesium, and rare earth element). Reaction conditions (solution pH, reaction temperature, sorbent dosage, and contact time) are of critical importance for the removal performance of contaminants onto OMC. In addition, the pristine and modified OMC have been investigated for the removal of a range of contaminants, including cationic/anionic toxic elements and organic contaminants (synthetic dye, phenol, and others), and involving different and specific mechanisms of interaction with contaminants. The future research directions of the application of pristine and modified OMC were proposed. Overall, this review can provide sights into the modification techniques of OMC for removal of environmental contaminants.
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http://dx.doi.org/10.1016/j.jhazmat.2021.126266DOI Listing
May 2021

Simultaneous reduction and immobilization of Cr(VI) in seasonally frozen areas: Remediation mechanisms and the role of ageing.

J Hazard Mater 2021 08 17;415:125650. Epub 2021 Mar 17.

School of Environment, Tsinghua University, Beijing 100084, China. Electronic address:

Among the toxic metals, hexavalent chromium [Cr(VI)] has attracted much attention due to its high mobility and toxicity, rendering considerable challenges for long-term remediation. In this study, the soil was collected from a dichromate contaminated industrial site in Liaoning Province, a seasonally frozen area in northern China, and subjected to frequent freeze-thaw cycles. Three additives, including (i) ferrous sulfate; (ii) calcium polysulfide; and (iii) combined biochar and calcium polysulfide were applied to reduce and immobilize Cr(VI) in the soils. The samples underwent 28 days of incubation followed by 16 freeze-thaw cycles. The toxicity characteristic leaching procedure (TCLP) and simulated acid rain leaching were adopted to test the remediation performances. It was observed that all three treatments can significantly reduce and immobilize Cr(VI) after short-term incubation, while biochar with abundant functional groups could adsorb and reduce Cr(VI) effectively. Notably, the concentration of Cr(VI) in TCLP leachates after incubation in combined treatment decreased by 67.87% and 37.27%, respectively, compared with the application of ferrous sulfate or calcium polysulfide alone. Freeze-thaw cycles induced the disintegration of soil particles and increased the risk of contaminant mobilization. Conversely, biochar particles has become finer and even produced nanoparticles with ageing, accompanied by the increase in oxygen-containing surface functional groups. Additionally, the specific surface area increased with the pyrolysis of biochar, which further enhanced the retention of soil colloidal particles and suppressed the migration of contaminants. Therefore, the cumulative release of Cr(VI) in the combined treatment (i.e., 10.97 ~ 32.97 mg/kg) was much lower than that of the other two treatments after freeze-thaw ageing. Overall, the combination of biochar and calcium polysulfide displayed advantages in the reduction and immobilization of Cr(VI), and offered a long-term, effective strategy for the remediation of Cr(VI) contaminated soils in cold regions.
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http://dx.doi.org/10.1016/j.jhazmat.2021.125650DOI Listing
August 2021

In-situ generation of reactive oxygen species using combination of electrochemical oxidation and metal sulfide.

Sci Total Environ 2021 Oct 23;789:147961. Epub 2021 May 23.

Department of Environment & Energy, Jeonbuk National University, 567 Baekje-daero, Deokjin, Jeonju, Jeollabukdo 54896, Republic of Korea; Soil Environment Research Center, Jeonbuk National University, 567 Baekje-daero, Deokjin, Jeonju, Jeollabukdo 54896, Republic of Korea. Electronic address:

In-situ chemical oxidation (ISCO) is commonly practiced to degrade organic pollutants in various fields. However, ISCO is deteriorated the oxidation efficiency due to the non-selective and self-decomposition of reagents. Therefore, in-situ generation of oxidants is being proposed to compensate for the demerits of conventional ISCO. In this study, the aim is to suggest a novel in-situ generation system using the combination of electrochemical oxidation (EO) and pyrite oxidation. It is hypothesized that EO system can generate the oxygen species, which can activate the pyrite surface to produce more oxidants. We evaluated three systems (1) EO system (2) pyrite oxidation system (3) combined system using sulfanilamide as a common antibiotic. The EO system degraded completely sulfanilamide and generated 150 μM of HO and 8 mg/L of DO even at 10 mA. In other words, EO system can directly oxidize the sulfanilamide and produce oxygen species. The pyrite system produced 204 and 24 μM of hydroxyl radicals at pH 3 under oxic and anoxic conditions, respectively, and 118 and 20 μM at pH 7. Pyrite oxidation can generate more reactive species in the presence of oxygen. The combined system enhanced the oxidation-rate constant to 1.5 times (from 0.2561 to 0.3502 h). The additional supply of oxygen showed a higher oxidation rate to 1.5 and 1.3 times higher than single EO or pyrite oxidation, respectively. As a result, the co-presence of pyrite and oxygen shows a synergistic effect on the oxidation of the organic pollutant. Our results suggest that electrochemical generation of the oxygen species in the presence of pyrite is a promising technique to oxidize organic pollutants in groundwater.
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http://dx.doi.org/10.1016/j.scitotenv.2021.147961DOI Listing
October 2021

The kaolinite shuttle links the Great Oxidation and Lomagundi events.

Nat Commun 2021 05 19;12(1):2944. Epub 2021 May 19.

Department of Earth and Atmospheric Sciences, University of Alberta, Edmonton, Canada.

The ~2.22-2.06 Ga Lomagundi Event was the longest positive carbon isotope excursion in Earth's history and is commonly interpreted to reflect perturbations in continental weathering and the phosphorous cycle. Previous models have focused on mechanisms of increasing phosphorous solubilization during weathering without focusing on transport to the oceans and its dispersion in seawater. Building from new experimental results, here we report kaolinite readily absorbs phosphorous under acidic freshwater conditions, but quantitatively releases phosphorous under seawater conditions where it becomes bioavailable to phytoplankton. The strong likelihood of high weathering intensities and associated high kaolinite content in post-Great-Oxidation-Event paleosols suggests there would have been enhanced phosphorus shuttling from the continents into marine environments. A kaolinite phosphorous shuttle introduces the potential for nonlinearity in the fluxes of phosphorous to the oceans with increases in chemical weathering intensity.
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http://dx.doi.org/10.1038/s41467-021-23304-8DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8134571PMC
May 2021

Comparison of the Hydraulic Fracturing Water Cycle in China and North America: A Critical Review.

Environ Sci Technol 2021 06 10;55(11):7167-7185. Epub 2021 May 10.

Department of Earth and Atmospheric Sciences, University of Alberta, Edmonton, Alberta, Canada.

There is considerable debate about the sustainability of the hydraulic fracturing (HF) water cycle in North America. Recently, this debate has expanded to China, where HF activities continue to grow. Here, we provide a critical review of the HF water cycle in China, including water withdrawal practices and flowback and produced water (FPW) management and their environmental impacts, with a comprehensive comparison to the U.S. and Canada (North America). Water stress in arid regions, as well as water management challenges, FPW contamination of aquatic and soil systems, and induced seismicity are all impacts of the HF water cycle in China, the U.S., and Canada. In light of experience gained in North America, standardized practices for analyzing and reporting FPW chemistry and microbiology in China are needed to inform its efficient and safe treatment, discharge and reuse, and identification of potential contaminants. Additionally, conducting ecotoxicological studies is an essential next step to fully reveal the impacts of accidental FPW releases into aquatic and soil ecosystems in China. From a policy perspective, the development of China's unconventional resources lags behind North America's in terms of overall regulation, especially with regard to water withdrawal, FPW management, and routine monitoring. Our study suggests that common environmental risks exist within the world's two largest HF regions, and practices used in North America may help prevent or mitigate adverse effects in China.
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http://dx.doi.org/10.1021/acs.est.0c06119DOI Listing
June 2021

Hydraulic Fracturing Return Fluids from Offshore Hydrocarbon Extraction Present New Risks to Marine Ecosystems.

Environ Sci Technol 2021 04 22;55(8):4199-4201. Epub 2021 Mar 22.

Department of Ocean Science, Division of Life Science and Hong Kong Branch of the Southern Marine Science and Engineering Guangdong Laboratory (Guangzhou), The Hong Kong University of Science and Technology, Kowloon, Hong Kong 999077, China.

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http://dx.doi.org/10.1021/acs.est.1c00107DOI Listing
April 2021

A complex bioaccumulation story in flowback and produced water from hydraulic fracturing: The role of organic compounds in inorganic accumulation in Lumbriculus variegatus.

J Hazard Mater 2021 07 25;414:125525. Epub 2021 Feb 25.

Department of Biological Sciences, University of Alberta, Edmonton T6G 2E9, Alberta, Canada; National Research Council of Canada Nanotechnology Initiative, Edmonton T6G 2M9, Alberta, Canada.

Hydraulic fracturing creates large volumes of flowback and produced water (FPW). The waste is a complex mixture of organic and inorganic constituents. Although the acute toxicity of FPW to freshwater organisms has been studied, few have attempted to discern the interaction between organic and inorganic constituents within this matrix and its role in toxicity. In the present study, bioaccumulation assays (7-d uptake and 7-d elimination period) with FPW (1% dilution) were conducted with the freshwater oligochaete, Lumbriculus variegatus, to evaluate the toxicokinetics of inorganic elements. To evaluate the interacting role of organics, bioaccumulation of elements in unmodified FPW was compared to activated carbon treated FPW (AC-modified). Differences in uptake and elimination rates as well as elimination steady state concentrations between unmodified and AC-modified treatments indicated that the organics play an important role in the uptake and depuration of inorganic elements in FPW. These differences in toxicokinetics between treatments aligned with observed growth rates in the worms which were higher in the AC-modified treatment. Whether growth differences resulted from increased accumulation and changes in toxicokinetic rates of inorganics or caused by direct toxicity from the organic fraction of FPW itself is still unknown and requires further research.
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http://dx.doi.org/10.1016/j.jhazmat.2021.125525DOI Listing
July 2021

Effect of temperature on phenanthrene accumulation from hydraulic fracturing flowback and produced water in rainbow trout (Oncorhynchus mykiss).

Environ Pollut 2021 Mar 30;272:116411. Epub 2020 Dec 30.

Department of Biological Sciences, University of Alberta, Edmonton, Alberta, Canada; NRC-University of Alberta Nanotechnology Initiative, Nanotechnology Research Centre, Edmonton, Canada.

Hydraulic fracturing has become widely used in recent years to access vast global unconventional sources of oil and gas. This process involves the injection of proprietary mixtures of water and chemicals to fracture shale formations and extract the hydrocarbons trapped within. These injection fluids, along with minerals, hydrocarbons, and saline waters present within the formations being drilled into, return to the surface as flowback and produced water (FPW). FPW is a highly complex mixture, containing metals, salts and clay, as well as many organic chemicals, including polycyclic aromatic hydrocarbons such as phenanthrene. The present study sought to determine the effects of temperature on the accumulation of phenanthrene in rainbow trout (Oncorhynchus mykiss). This model organism resides in rivers overlapping the Montney and Duvernay formations, both highly developed formations for hydraulic fracturing. Rainbow trout acclimated to temperatures of 4, 13 and 17 °C were exposed to either 5% or 20% FPW, as well as saline mixtures representing the exact ionic content of FPW to determine the accumulation of radiolabelled C phenanthrene within the gill, gut, liver and gallbladder. FPW exposure reduced the overall accumulation of phenanthrene in a manner most often similar to high salinity exposure, indicating that the high ionic strength of FPW is the primary factor affecting accumulation. Accumulation was different at the temperature extremes (4 and 17 °C), although no consistent relationship was observed between temperature and accumulation across the observed tissues. These results indicate that several physiological responses occur as a result of FPW exposure and water temperature change which dictate phenanthrene uptake, particularly in the gills. Temperature (and seasonality) alone cannot be used to model the potential accumulation of polycyclic aromatic hydrocarbons after FPW spills.
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http://dx.doi.org/10.1016/j.envpol.2020.116411DOI Listing
March 2021

Group versus individual exposure: Do methodological decisions in aquatic toxicology alter experimental results?

Sci Total Environ 2021 Apr 29;764:144288. Epub 2020 Dec 29.

Department of Biological Sciences, University of Alberta, Edmonton, Alberta, Canada. Electronic address:

In aquatic toxicology, methods that are chosen for exposures have profound consequences on experimental outcomes and thus can skew policy initiatives. For example, as compared to single-organism exposures, toxicity test results of group exposures may be impacted by confounding factors such as social interactions between animals or individual variation in accumulation rates. To test for differences in organismal response between group and individual toxicological exposures, we exposed Daphnia magna to copper and subsequently compared the toxicity (median lethal concentration or LC50) between groups and individuals. Results suggested that water chemistry had a larger effect on experimental outcomes than the number of animals exposed in the same tank. Methodological decisions with respect to replication type can affect toxicity tests, and LC50s calculated using different exposure types (such as group and individual exposures) may not be comparable.
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http://dx.doi.org/10.1016/j.scitotenv.2020.144288DOI Listing
April 2021

Reusable magnetite nanoparticles-biochar composites for the efficient removal of chromate from water.

Sci Rep 2020 11 4;10(1):19007. Epub 2020 Nov 4.

Department of Earth and Atmospheric Sciences, University of Alberta, 1-26 Earth Sciences Building, Alberta, T6G 2E3, Canada.

Biochar (BC) and magnetite (FeO) nanoparticles (MNP) have both received considerable recent attention in part due to their potential use in water treatment. While both are effective independently in the removal of a range of anionic metals from aqueous solution, the efficacy of these materials is reduced considerably at neutral pH due to decreased metal adsorption and MNP aggregation. In addition to synthetic metal oxide-biochar composites for use in treatment and remediation technologies, aggregates may also occur in nature when pyrolytic carbon is deposited in soils. In this study, we tested whether magnetite synthesized in the presence of biochar leads to increased removal efficiency of hexavalent chromium, Cr(VI), at the mildly acidic to neutral pH values characteristic of most natural and contaminated aqueous environments. To do so, magnetite nanoparticles and biochar produced from ground willow were synthesized to form composites (MNP-BC). Batch studies showed that MNP-BC markedly enhanced both adsorption and reduction of Cr(VI) from aqueous solution at acidic to neutral pH as compared to MNP and BC separately, suggesting a strong synergetic effect of hybridizing FeO with BC. Mechanistically, the Cr(VI) removal processes occurred through both adsorption and intraparticle diffusion followed by reduction to Cr(III). Synchrotron-based X-ray absorption spectroscopy analyses confirmed that Cr(VI) was reduced at the surface of MNP-BC, with electrons derived directly from both biochar and magnetite at low pH, while at near-neutral pH, biochar increased Cr(VI) reduction by inhibiting MNP aggregation. Extended X-ray absorption fine structure fitting results confirmed that the Cr(III) precipitates consist of Cr(OH) and chromite (CrFeO) nanoparticles. Our results demonstrate that MNP-BC composites have great potential as a material for the treatment of chromate-containing aqueous solutions across a wide range of pH values, and provide information valuable broadly relevant to soils and sediments that contain biochar.
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http://dx.doi.org/10.1038/s41598-020-75924-7DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7642354PMC
November 2020

Exposure to Hydraulic Fracturing Flowback Water Impairs () Cardiomyocyte Contractile Function and Swimming Performance.

Environ Sci Technol 2020 11 14;54(21):13579-13589. Epub 2020 Oct 14.

Department of Marine Biology and Ecology, Rosenstiel School of Marine and Atmospheric Science, University of Miami, 4600 Rickenbacker Causeway, Miami, Florida 33149, United States.

Publicly available toxicological studies on wastewaters associated with unconventional oil and gas (UOG) activities in offshore regions are nonexistent. The current study investigated the impact of hydraulic fracturing-generated flowback water (HF-FW) on whole organism swimming performance/respiration and cardiomyocyte contractility dynamics in mahi-mahi (-hereafter referred to as "mahi"), an organism which inhabits marine ecosystems where offshore hydraulic fracturing activity is intensifying. Following exposure to 2.75% HF-FW for 24 h, mahi displayed significantly reduced critical swimming speeds () and aerobic scopes (reductions of ∼40 and 61%, respectively) compared to control fish. Additionally, cardiomyocyte exposures to the same HF-FW sample at 2% dilutions reduced a multitude of mahi sarcomere contraction properties at various stimulation frequencies compared to all other treatment groups, including an approximate 40% decrease in sarcomere contraction size and a nearly 50% reduction in sarcomere relaxation velocity compared to controls. An approximate 8-fold change in expression of the cardiac contractile regulatory gene was also seen in ventricles from 2.75% HF-FW-exposed mahi. These results collectively identify cardiac function as a target for HF-FW toxicity and provide some of the first published data on UOG toxicity in a marine species.
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http://dx.doi.org/10.1021/acs.est.0c02719DOI Listing
November 2020

Changes to hepatic nutrient dynamics and energetics in rainbow trout (Oncorhynchus mykiss) following exposure to and recovery from hydraulic fracturing flowback and produced water.

Sci Total Environ 2021 Apr 14;764:142893. Epub 2020 Oct 14.

Department of Biological Sciences, University of Alberta, Edmonton, AB T6G 2E9, Canada.

Hydraulic fracturing flowback and produced water (FPW) is a highly complex and heterogenous wastewater by-product of hydraulic fracturing practices. To date, no research has examined how FPW exposure to freshwater biota may affect energetic homeostasis following subsequent induction of detoxification processes. Rainbow trout (Oncorhynchus mykiss) were acutely exposed for 48 h to either 2.5% or 7.5% FPW, and hepatic metabolism was assessed either immediately or following a 3-week recovery period. Induction of xenobiotic metabolism was observed with an 8.8-fold increase in ethoxyresorufin-O-deethylase (EROD) activity after 48 h exposure to 7.5% FPW, alongside a 10.3-fold increase in the mRNA abundance of cyp1a, both of which returned to basal level after three weeks. Glucose uptake capacity was elevated by 6.8- and 12.9-fold following 2.5% and 7.5% FPW exposure, respectively, while alanine uptake was variable. Activity measurements and mRNA abundance of key enzymes involved in hepatic metabolism indicated that aerobic metabolism was maintained with exposure, as was glycolysis. Gluconeogenesis, as measured by phosphoenolpyruvate carboxykinase (PEPCK) activity, decreased by ~30% 48 h following 2.5% FPW exposure and ~20% 3 weeks after 7.5% FPW exposure. The abundance of pepck mRNA activity followed similar, yet non-significant, trends. Finally, a delayed increase in amino acid catabolism was observed, as glutamate dehydrogenase (GDH) activity was increased 2-fold in 7.5% FPW exposed fish when compared to saline  control fish at the 3-week time point. We provide evidence to suggest that although hepatic metabolism is altered following acute FPW exposure, metabolic homeostasis generally returns 3-weeks post-exposure.
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http://dx.doi.org/10.1016/j.scitotenv.2020.142893DOI Listing
April 2021

Effects of aging and weathering on immobilization of trace metals/metalloids in soils amended with biochar.

Environ Sci Process Impacts 2020 Sep;22(9):1790-1808

Korea Biochar Research Center & Division of Environmental Science and Ecological Engineering, Korea University, Seoul, Korea. and Department of Environmental Engineering, China Jiliang University, No. 258 Xueyuan Street, Hangzhou, Zhejiang 310018, P. R. China.

Biochar is an effective amendment for trace metal/metalloid (TMs) immobilization in soils. The capacity of biochar to immobilize TMs in soil can be positively or negatively altered due to the changes in the surface and structural chemistry of biochar after soil application. Biochar surfaces are oxidized in soils and induce structural changes through physical and biochemical weathering processes. These changes in the biochar surface and structural chemistry generally increase its ability to immobilize TMs, although the generation of dissolved black carbon during weathering may increase TM mobility. Moreover, biochar modification can improve its capacity to immobilize TMs in soils. Over the short-term, engineered/modified biochar exhibited increased TM immobilization capacity compared with unmodified biochar. In the long-term, no large distinctions in such capacities were seen between modified and unmodified biochars due to weathering. In addition, artificial weathering at laboratories also revealed increased TM immobilization in soils. Continued collection of mechanistic evidence will help evaluate the effect of natural and artificial weathering, and biochar modification on the long-term TM immobilization capacity of biochar with respect to feedstock and synthesis conditions in contaminated soils.
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http://dx.doi.org/10.1039/d0em00057dDOI Listing
September 2020

Clay minerals as a source of cadmium to estuaries.

Sci Rep 2020 06 26;10(1):10417. Epub 2020 Jun 26.

Department of Earth & Atmospheric Sciences, University of Alberta, Edmonton, Alberta, T6G 2E3, Canada.

Given the high surface reactivity of clay minerals, it is assumed that flocculation will lead to metal accumulation in marginal marine settings. However, the degree of metal sorption to clays is impacted by solution pH and ionic strength, and it remains unknown whether riverine clays indeed serve as a metal sink once they encounter seawater where pH and ionic strength markedly increase. Here, we conducted cadmium (Cd) adsorption experiments to three types of common clay minerals - kaolinite, illite and montmorillonite. We found that 20-30% of Cd from illite and montmorillonite surfaces were desorbed when transitioning from freshwater to seawater pH and ionic strength conditions, while kaolinite showed no discernible differences. Synchrotron X-ray adsorption spectroscopy confirmed that Cd release corresponded to a change in bonding from outer- to inner-sphere complexes when clays encountered seawater pH and ionic strength conditions. If other trace nutrients (such as Cu, Zn, Co) adsorbed onto riverine clay minerals behave in a similar manner to Cd, we speculate that their desorption in marginal marine settings should exert a significant impact on the productivity of the biosphere.
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http://dx.doi.org/10.1038/s41598-020-67279-wDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7320025PMC
June 2020

Competitive adsorption of heavy metals by anaerobic ammonium-oxidizing (anammox) consortia.

Chemosphere 2020 Nov 6;258:127289. Epub 2020 Jun 6.

State Key Laboratory of Water and Sediment Sciences (Ministry of Education), College of Environmental Science & Engineering, Peking University, Beijing, 100871, China. Electronic address:

Anammox-based processes and microbial consortia have drawn extensive attention for their use in high-efficiency wastewater treatment technologies. Metals substantially affect the activity of anammox consortia and the quality of wastewater treatment plant effluent. Here, we explored the role of anammox consortia in terms of metals complexation in both single and multi-metal systems. Adsorption edges of single metal cations indicate that the adsorption preference was in the order: Pb(II) > Cd(II) > Cr(VI). A competitive effect was observed in multi-metal cations systems, with Pb(II) being preferably adsorbed and the degree of adsorption somewhat reduced in the presence of either Cd(II) or Cr(VI), while Cd(II) and Cr(VI) were easily exchanged and substituted by other metals. Fourier transform infrared (FTIR) and X-ray photoelectron spectroscopy (XPS) further suggest that the adsorption of Pb(II) and Cd(II) are as inner-sphere ion-exchange mechanisms, while Cr(VI) adsorption is mainly by outer-sphere complexation. Density functional theory (DFT) calculations highlight that Cd(II) and Pb(II) have different binding sites compared to Cr(VI), and the order of binding energy (E) of three metal cations were Pb(II) > Cd(II) > Cr(VI). These calculations support the adsorption data in that Pb forms more stable complexes with anammox bacterial surface ligands. Surface complexation modelling (SCM) further predicted both the sorption of single metal cations and competitive adsorption of the three metals to anammox consortia, the exception being Cd at higher loadings. The results of this study highlight the potential role of anammox consortia in removing metal cations from wastewater in treatment systems.
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http://dx.doi.org/10.1016/j.chemosphere.2020.127289DOI Listing
November 2020

Redox-induced mobilization of Ag, Sb, Sn, and Tl in the dissolved, colloidal and solid phase of a biochar-treated and un-treated mining soil.

Environ Int 2020 07 1;140:105754. Epub 2020 May 1.

Korea Biochar Research Center, O-Jeong Eco-Resilience Institute (OJERI) & Division of Environmental Science and Ecological Engineering, Korea University, Seoul 02841, Republic of Korea. Electronic address:

The aim of this work was to study the redox-induced mobilization of Ag, Sb, Sn, and Tl in the dissolved, colloidal, and sediment phase of a mining soil treated and untreated with biochar as affected by the redox potential (E) -dependent changes of soil pH, dissolved organic carbon, Fe, Mn and S. The experiment was conducted stepwise at two E cycles (+200 mV → -30 mV → +333 mV → 0 mV) using biogeochemical microcosm. Silver was abundant in the colloidal fraction in both cycles, indicating that Ag might be associated with colloids under different redox conditions. Antimony, Sn and Tl were abundant in the colloidal fraction in the first cycle and in the dissolved fraction in the second cycle, which indicates that they are retained by colloids under oxic acidic conditions and released under reducing alkaline conditions. Release of dissolved Sb, Sn, and Tl was governed positively by pH, Fe, S, and dissolved aromatic compounds. Biochar mitigated Ag release, but promoted Sb, Sn, and Tl mobilization, which might be due to the wider range of E (-12 to +333) and pH (4.9-8.1) in the biochar treated soil than the un-treated soil (E = -30 to +218; pH = 5.9-8.6). Also, the biochar surface functional groups may act as electron donors for the Sb, Sn, and Tl reduction reactions, and thus biochar may play an important role in reducing Tl to Tl, Sb to Sb, and Sn to Sn, which increase their solubility under reducing conditions as compared to oxic conditions. Thallium and Sb exhibit higher potential mobility in the solid phase than Sn and Ag. Biochar increased the potential mobility of Sb, Sn, and Tl under oxic acidic conditions. The results improve our understanding of the redox-driven mobilization of these contaminants in soils.
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http://dx.doi.org/10.1016/j.envint.2020.105754DOI Listing
July 2020

Using CO as an Oxidant in the Catalytic Pyrolysis of Peat Moss from the North Polar Region.

Environ Sci Technol 2020 05 6;54(10):6329-6343. Epub 2020 May 6.

Department of Environment and Energy, Sejong University, Seoul 05006, Republic of Korea.

As global warming and climate change become perceived as significant, the release of greenhouse gases (GHGs) stored in the earth's polar regions is considered a matter of concern. Here, we focused on exploiting GHGs to address potential global warming challenges in the north polar regions. In particular, we used CO as a soft oxidant to recover energy as syngas (CO and H) and to produce biochars from pyrolysis of peat moss. CO expedited homogeneous reaction with volatile matters from peat moss pyrolysis, and the mechanistic CO role resulted in the conversion of CO and peat moss to CO at ≥530 °C. Steel slag waste was then used as an ex situ catalyst to increase reaction kinetics, addressing the issue of the role of CO being limited to ≥530 °C, with the result where substantial H and CO formation was achieved at a milder temperature. The porosity of biochars, a solid peat moss pyrolysis product, was modified in the presence of CO, with a significant improvement in CO adsorption capacity compared to those achieved by N pyrolysis. Therefore, CO has the potential to serve as an initial feedstock in sustainable biomass-to-energy applications and biochar production, mitigating atmospheric carbon concentrations.
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http://dx.doi.org/10.1021/acs.est.0c01862DOI Listing
May 2020

Response of aquatic microbial communities and bioindicator modelling of hydraulic fracturing flowback and produced water.

FEMS Microbiol Ecol 2020 05;96(5)

Department of Earth and Atmospheric Sciences, Faculty of Science, University of Alberta, Edmonton, Canada.

The response of microbial communities to releases of hydraulic fracturing flowback and produced water (PW) may influence ecosystem functions. However, knowledge of the effects of PW spills on freshwater microbiota is limited. Here, we conducted two separate experiments: 16S rRNA gene sequencing combined with random forests modelling was used to assess freshwater community changes in simulated PW spills by volume from 0.05% to 50%. In a separate experiment, live/dead cell viability in a freshwater community was tested during exposure to 10% PW by volume. Three distinct patterns of microbial community shifts were identified: (i) indigenous freshwater genera remained dominant in <2.5% PW, (ii) from 2.5% to 5% PW, potential PW organic degraders such as Pseudomonas, Rheinheimera and Brevundimonas became dominant, and (iii) no significant change in the relative abundance of taxa was observed in >5% PW. Microbial taxa including less abundant genera such as Cellvibrio were potential bioindicators for the degree of contamination with PW. Additionally, live cells were quickly damaged by adding 10% PW, but cell counts recovered in the following days. Our study shows that the responses of freshwater microbiota vary by spill size, and these responses show promise as effective fingerprints for PW spills in aquatic environments.
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http://dx.doi.org/10.1093/femsec/fiaa068DOI Listing
May 2020

Hydro-climate and biogeochemical processes control watershed organic carbon inflows: Development of an in-stream organic carbon module coupled with a process-based hydrologic model.

Sci Total Environ 2020 May 13;718:137281. Epub 2020 Feb 13.

Department of Earth and Atmospheric Sciences, University of Alberta, 1-26 Earth Sciences Building, Edmonton, AB T6G 2E3, Canada. Electronic address:

Dissolved organic carbon (DOC) in surface waters directly influences the speciation, transport, and fate of heavy metals, as well as the partitioning of organic contaminants. However, the lack of process-based watershed-scale models for simulating carbon cycling and transport has limited the effective watershed management to control organic carbon fluxes to source waters and throughout the river systems. Here, a process-based in-stream organic carbon (OC) module was developed, coupled with the physically process-based Soil and Water Assessment Tool (SWAT), and linked with its existing soil carbon module to simulate dynamics of both particulate organic carbon (POC) and DOC. The advanced model simulates a large spectrum of OC processes from landscapes to stream networks throughout the watersheds. In-stream organic carbon processes related to POC and DOC as state variables are modeled in the water column, and the transformations between different carbon species and interactions between OC with algae are considered. The module's ability to simulate total organic carbon (TOC) loads was assessed, and the monthly and seasonal variations were captured over 14 years. Simulations for TOC loads suggested that spring snowmelt and summer rainfall runoff events are the main driving forces behind TOC export in the watershed. The parameter sensitivity analysis and dynamic reaction rate simulated in the streams suggested that TOC dynamics in the study area are controlled by both landscape and in-stream processes. The spatiotemporal analysis of the simulated TOC load showed that 55.8% of total terrestrial OC exports into the streams are removed due to in-stream POC settling and DOC mineralization, confirming the necessity of integrating terrestrial and aquatic OC processes for process understanding and for modelling and management of water quality at the watershed scale. The developed OC module is a potentially effective tool for simulating the OC cycle at the watershed scale and can be applied further to water treatment plans and watershed management.
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http://dx.doi.org/10.1016/j.scitotenv.2020.137281DOI Listing
May 2020

Effects of excessive impregnation, magnesium content, and pyrolysis temperature on MgO-coated watermelon rind biochar and its lead removal capacity.

Environ Res 2020 04 20;183:109152. Epub 2020 Jan 20.

Department of Earth and Atmospheric Sciences, University of Alberta, Edmonton, T6G 2E3, Canada.

MgO-coated watermelon rind biochar (MWRB) is a potentially highly-effective waste-derived material in environmental applications. This research aims to provide valuable insights into the optimization of the production of MWRB for superior environmental performance. It was found that the Mg content of the MWRB could be easily controlled by adjusting the Mg/feedstock mass ratio during excessive impregnation. The BET surface area was found to first increase and then decrease as the Mg content of the MWRB (produced at 600 °C) increased from 1.52% to 10.1%, with an optimal surface area of 293 m/g observed at 2.51%. Similarly, an optimum pyrolysis temperature of 600 °C was observed in the range of 400-800 °C for a maximum surface area of the MWRB at a fixed Mg/feedstock ratio of 0.48% (resulting in MWRBs with Mg contents of 1.89-2.51%). The Pb removal capacity of the MWRB (produced at 600 °C) increased with increasing Mg content, with a greatest Pb removal capacity of 558 mg/g found for the MWRB with the highest Mg content (10.1%), an improvement of 208% over the 181 mg/g Pb removal capacity of unmodified WRB produced at 600 °C. The Pb removal capacity of the MWRB (produced with 1.89-2.51% Mg) was also discovered to increase from 81.7 mg/g (at 400 °C) to 742 mg/g (at 700 °C), before dropping to 368 mg/g at 800 °C. These findings suggest that the MWRB can be more efficiently utilized in soil and water remediation by optimizing its synthesis conditions.
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http://dx.doi.org/10.1016/j.envres.2020.109152DOI Listing
April 2020

Heavy metal dissolution mechanisms from electrical industrial sludge.

Sci Total Environ 2019 Dec 14;696:133922. Epub 2019 Aug 14.

Korea Biochar Research Center & Division of Environmental Science and Ecological Engineering, Korea University, Seoul 02841, Republic of Korea. Electronic address:

In this paper, we investigate the release of heavy metals from sludge produced from an electrical industry using both organic and inorganic acids. Single and sequential extractions were conducted to assess heavy metals in different phases of the sludge. Metal release from sludge was investigated in the presence of three inorganic acids (nitric, sulfuric, and phosphoric) and three organic acids (acetic, malic, and citric) at concentrations ranging from 0.1 to 2.0 mol L. Sequential extraction indicated the presence of Cu primarily in the carbonate fraction, Pb in the residual fraction, and Ni in the FeMn oxide fraction. The cumulative release rates of heavy metals (i.e., Pb, Cu, and Ni) by 1.0 mol L of acid increased with the use of the following acids in the order of: malic < sulfuric < acetic < phosphoric < citric < nitric. Acetic acid exhibited the highest release of Cu, at a rate of 72.62 × 10 mol m s at pH 1, and malic acid drove the release of Pb at a maximum rate of 3.90 × 10 mol m s. Meanwhile, nitric acid provided the maximum rate of Ni release (0.23 × 10 mol m s) at pH 1. The high rate of metal release by organic acids is explained through ligand-promoted mechanisms that enhance the release of metal ions from the sludge. The results from our study emphasize that an understanding of the metal release mechanism is key to selecting the optimal acid for the maximum recovery of heavy metals.
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http://dx.doi.org/10.1016/j.scitotenv.2019.133922DOI Listing
December 2019

Correction to "Mechanism of Goethite Precipitation on Magnetite and Maghemite Nanoparticles Studied by Surface Complexation/Precipitation Modeling".

Langmuir 2019 Aug 24;35(32):10676. Epub 2019 Jul 24.

Department of Chemical and Materials Engineering , University of Alberta , Edmonton , Alberta , Canada T6G 1H9.

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http://dx.doi.org/10.1021/acs.langmuir.9b01709DOI Listing
August 2019

Potential of asphalt concrete as a source of trace metals.

Environ Geochem Health 2020 Feb 15;42(2):397-405. Epub 2019 Jul 15.

Department of Earth and Atmospheric Sciences, University of Alberta, 1-26 Earth Sciences Building, Edmonton, T6G 2E3, Canada.

Asphalt concrete is one of the most important building materials in the modern world, but the leaching potential of metals from this composite material to the environment is poorly understood. In this study, metals leaching from four hot-mix asphalt samples were analyzed: two fresh samples of low-traffic and high-traffic composition and their weathered equivalents collected from roads in the city of Edmonton, Alberta, Canada. A sequential extraction, based on the Community Bureau of Reference method, was applied to study the speciation and potential mobility of metals and metalloids in those samples. Major trace metals identified in all four samples were Mn, P, Ba, Sr, Zn, V, and Ni, with the highest metals concentrations generally found in weathered asphalt concrete. Of the major trace metals, P, Mn, Sr, and Zn were relatively mobile, having large portions of their total concentrations in the exchangeable/acid-soluble and reducible fractions. When considering the most mobile fraction (exchangeable/acid soluble) and using Canada as a model country, up to 180 t P, 440 t Mn, 50 t Ba, 36 t Sr, 11 t Zn, and 0.11-3.2 t of other metals and metalloids (including Cr, Ni, Cu, As, and Pb) could potentially leach from the top layer of Canada's total of paved public roads. To place these amounts into perspective, they were estimated to make up to 22‰ of Canada's annual release numbers into soil, water and air for these same metals and metalloids. However, they are concentrated in a small area around roads and highways, creating the potential for localized soil and groundwater contamination.
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http://dx.doi.org/10.1007/s10653-019-00370-yDOI Listing
February 2020

Temporal effect of MgO reactivity on the stabilization of lead contaminated soil.

Environ Int 2019 10 11;131:104990. Epub 2019 Jul 11.

Department of Earth and Atmospheric Sciences, University of Alberta, Edmonton T6G 2E3, Canada.

Elevated soil lead (Pb) concentrations are a global concern owing to the toxic effects of this heavy metal. Solidification/stabilization (S/S) of soils using reagents like Portland cement (PC) is a common approach for the remediation of Pb contaminated sites. However, it has been reported that under long-term field conditions, the performance of PC treatments can diminish significantly. Therefore, novel reagents that provide longer-term stabilization performance are needed. In this study, four magnesium oxide (MgO) products of different reactivity values were applied (5 wt%) to a Pb contaminated clayey soil. The short-term (1-49 days) and long-term (25-100 years) temporal stabilization effects were investigated by laboratory incubation and accelerated ageing methods, respectively. The concentration of Pb in Toxicity Characterization Leaching Procure (TCLP) leachate was ~14 mg/L for the untreated soil; ~1.8 times higher than the TCLP regulatory level (5 mg/L). Only one day after treatment with MgO, the leachate concentration was reduced to below the regulatory level (a reduction of 69.4%-83.2%), regardless of the MgO type applied. However, in the long-term accelerated ageing experiments, only treatments using the most reactive MgO type could provide leachate concentrations that were consistently below the TCLP threshold throughout the 100 years of simulated ageing. The soil treated with the MgO of lowest reactivity was the first to exceed the regulatory level, at simulated year 75. It is thus demonstrated that MgO reactivity has a significant effect on its long-term effectiveness for contaminated soil stabilization. This is attributed to differences in their specific surface area and readiness to carbonate, which may facilitate the immobilization of Pb in the long term. It is also noteworthy that compared to PC, reactive MgO is more environmentally friendly owing to lower energy consumption and reduced CO emissions during its manufacture.
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http://dx.doi.org/10.1016/j.envint.2019.104990DOI Listing
October 2019

Removal of lead by rice husk biochars produced at different temperatures and implications for their environmental utilizations.

Chemosphere 2019 Nov 2;235:825-831. Epub 2019 Jul 2.

Department of Earth and Atmospheric Sciences, University of Alberta, Edmonton, T6G 2E3, Canada.

Rice husk is a common agricultural waste. The utilization of rice husk biochar depends on the characteristics of biochar and its interaction mechanisms with heavy metals. In the present study, rice husk biochars at three different temperatures 300, 500, and 700 °C were produced (RH300, RH500, and RH700). The characteristics of these rice husk biochars and their interaction mechanisms with lead (Pb) were investigated, in order to reveal the potential environmental applications of the biochars. It was observed that the surface area (from 0.632 to 193.149 m/g) and pH (from 7.13 to 9.80) of the rice husk biochars significantly increased as production temperature rose from 300 to 700 °C, while the number of functional groups (e.g., carboxyl) decreased. The Langmuir maximum removal capacity (Q) values for Pb are in the order of RH300 < RH500 < RH700 (14.1, 21.7, and 26.7 mg/g respectively). Although RH300 has the smallest Q value, its exchangeable Pb amount is the largest (2.61 versus 0.223-0.377 mg/g), suggesting RH300 may be suitable for water treatment due to the easy separation of immobilized Pb and better recycling usage. The Pb immobilized on RH500 and RH700 was mainly acidic soluble and generally stable. Hydrocerussite is one important form within the acidic soluble fraction. Within the generally stable formation, pyromorphite is a form for the immobilized Pb on the rice husk biochars, particularly for RH500 and RH700. These findings suggest RH500 and RH700 are of promising potential to be applied in soil remediation to immobilize Pb and reduce its environmental risks.
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http://dx.doi.org/10.1016/j.chemosphere.2019.06.237DOI Listing
November 2019

Nontarget profiling of organic compounds in a temporal series of hydraulic fracturing flowback and produced waters.

Environ Int 2019 10 5;131:104944. Epub 2019 Jul 5.

Department of Laboratory Medicine and Pathology, University of Alberta, Edmonton AB T6G 2G3, Canada; Department of Environmental Sciences and Analytical Chemistry, Stockholm University, Stockholm 10691, Sweden. Electronic address:

Hydraulic fracturing (HF) flowback and produced water (FPW) can be toxic to aquatic life but its chemical content is largely unknown, variable and complex. Seven FPW samples were collected from a HF operation in the Duvernay Formation (Alberta, Canada) over 30 days of flowback and characterized by a nontarget workflow based on high performance liquid chromatography - high resolution mass spectrometry (HRMS). A modified Kendrick mass defect plot and MS/MS spectral interpretation revealed seven series of homologues composed of ethylene oxide (i.e. -CHCHO-), among which a series of aldehydes was proposed as degradation products of polyethylene glycols, and two series of alkyl ethoxylate carboxylates could be proprietary HF additives. Many other ions were confidently assigned a formula by accurate mass measurement and were subsequently prioritized for identification by matching to records in ChemSpider and the US EPA's CompTox Chemistry Dashboard. Quaternary ammonium compounds, amine oxides, organophosphorous compounds, phthalate diesters and hydroxyquinoline were identified with high confidence by MS/MS spectra (Level 3), matching to reference spectra in MassBank (Level 2) or to authentic standards (Level 1). Temporal trends showed that most of the compounds declined in abundance over the first nine days of flowback, except for phthalate diesters and hydroxyquinoline that were still observed on Day 30 and had disappearance half-lives of 61 and 91 days, respectively. All the compounds followed first-order disappearance kinetics in flowback, except for polyoxygenated acids which followed second-order kinetics. This analysis and the workflow, based largely on public on-line databases, enabled profiling of complex organic compounds in HF-FPW, and will likely be useful for further understanding the toxicity and chemical fate of HF-FPW.
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http://dx.doi.org/10.1016/j.envint.2019.104944DOI Listing
October 2019

Risk evaluation of biochars produced from Cd-contaminated rice straw and optimization of its production for Cd removal.

Chemosphere 2019 Oct 29;233:149-156. Epub 2019 May 29.

Department of Earth and Atmospheric Sciences, University of Alberta, Edmonton, T6G 2E3, Canada.

Based on the "waste-treat-waste" concept, biochars were produced from cadmium (Cd)-contaminated rice straw (CRSBs) at 300, 500, and 700 °C (CRSB300, CRSB500, and CRSB700). The risks of the Cd remaining in CRSBs were evaluated and the optimal biochar pyrolysis temperature for Cd removal was investigated. It was observed that 41% of the total Cd in the raw rice straw was exchangeable, which may pose significant risks to crops and humans. Pyrolyzing at 300 °C did not significantly alter the Cd fractions, while the exchangeable fraction of Cd greatly dropped to 5.79% at 500 °C and further to 2.12% at 700 °C. Increasing the highest pyrolysis temperature resulted in CRSBs with higher pH values, greater surface area, and smaller pore sizes, thus providing more rapid and efficient removal of Cd from aqueous solutions. For Cd removal tests, increasing pyrolysis temperature (300-700 °C) increased the total (24.8-55.1 mg/g) and non-exchangeable (18.9-52.8 mg/g) Cd concentrations immobilized on the CRSBs and significantly decreased the exchangeable Cd fraction (23.7%-4.85%). It is suggested based on the study from aqueous solutions that CRSB700 was the most suitable for the remediation of Cd contaminated soil on site due to the lowest risks of remained Cd from feedstock, fastest and highest Cd removal, and most stable immobilization of Cd.
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http://dx.doi.org/10.1016/j.chemosphere.2019.05.238DOI Listing
October 2019
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