14141. 题目: Integrating organic chemical simulation module into SWAT model with application for PAHs simulation in Athabasca oil sands region, Western Canada
期刊: Environmental Modelling and Software
作者: Xinzhong Du, Narayan Kumar Shrestha, Juyne Wang
摘要: An integrated watershed model is a key tool for assessing the fate and transport of organic chemicals. We developed and integrated an organic chemical simulation module into Soil Water Assessment Tool (SWAT) model and used it for Polycyclic Aromatic Hydrocarbons (PAHs) simulation in Muskeg River Watershed (MRW) in Athabasca oil sands region, Western Canada. The model uses a three-phase partition process to simulate the chemicals partitioning to Dissolved Organic Carbon (DOC) in both soil water and streams. The modeling performances for Phenanthrene and Pyrene loads for a period of 2015–2017 were assessed to be of ‘satisfactory’ quality. The model simulation results indicated that the summer season is the hot moment and the rainfall derived runoff event is the driving force for the PAHs transport in the watershed. The developed simulation module could be a useful modeling tool to simulate the fate and transport of organic chemicals at the watershed scale.
14142. 题目: Procedure for Organic Matter Removal from Peat Samples for XRD Mineral Analysis
作者: Jenny K. Sjöström, Richard Bindler, Therese Granberg, Malin E. Kylander
摘要: Ombrotrophic peatlands are recognized archives of past atmospheric mineral dust deposition. Net dust deposition rates, grain size, mineral hosts and source areas are typically inferred from down-core elemental data. Although elemental analysis can be time efficient and data rich, there are some inherent limitations. X–ray diffraction (XRD) analysis allows direct identification of mineral phases in environmental samples but few studies have applied this method to peat samples and a well–developed protocol for extracting the inorganic fraction of highly organic samples (>95%) is lacking. We tested and compared different levels of pre–treatment: no pre–treatment, thermal combustion (300, 350, 400, 450, 500 and 550 °C) and chemical oxidation (H2O2 and Na2S2O8) using a homogenised highly organic (>98%) composite peat sample. Subsequently, minerals were identified by XRD. The results show that combustion is preferred to chemical oxidation because it most efficiently removes organic matter (OM), an important pre–requisite for identifying mineral phases by XRD analysis. Thermally induced phase transitions can be anticipated when temperature is the only factor to take into consideration. Based on the data required in this study the recommended combustion temperature is 500 °C which efficiently removes OM while preserving a majority of common dust minerals.
14143. 题目: Microscale magnesium distribution in shell of the Mediterranean mussel Mytilus galloprovincialis: An example of multiple factors controlling Mg/Ca in biogenic calcite
期刊: Chemical Geology
作者: Kentaro Tanaka, Nobuyuki Okaniwa, Tsuzumi Miyaji, Naoko Murakami-Sugihara, Liqiang Zhao, Kazushige Tanabe, Bernd R. Schöne, Kotaro Shirai
摘要: Since magnesium concentration (Mg/Ca) in biogenic calcite is considered to reflect water temperature during precipitation, the magnesium-to‑calcium ratio has been examined as a proxy for water temperature in paleoclimate research, although factors other than temperature may also influence Mg/Ca in biogenic calcite, thereby introducing a potential bias in the relationship between Mg/Ca and temperature observed in inorganic systems. To better understand factors controlling Mg incorporation into the calcitic shells of bivalves, the distribution of Mg in the Mediterranean mussel Mytilus galloprovincialis was studied, being compared with ambient sea surface temperature (SST), shell growth rate and the distribution of organic matter. Although a positive relationship between Mg/Ca and SST was observed, Mg/Ca had been influenced by additional factors, including the enhancement of Mg incorporation by organic matter, evidenced by the growth line being more Mg-enriched than the growth increments. Furthermore, Mg/Ca was relatively enriched in the undulating (higher curvature) shell portion, being linked to neither SST, growth rate or organic matter. Zoning of Mg2+/Ca2+ within extrapallial fluid at the time of undulating shell portion formation was hypothesized, and heterogeneous Mg distribution in contemporaneously formed shell portions concluded as limiting the usability of Mytilus shell Mg/Ca as a proxy for water temperature.
14144. 题目: The role of Pleistocene meltwater-controlled uranium leaching in assessing irradiation-induced alteration of organic matter and petroleum potential in the Tremadocian Koporie Formation (Western Russia)
期刊: Geochimica et Cosmochimica Acta
作者: Hans-Martin Schulz, Shengyu Yang, Elena Panova, Achim Bechtel
摘要: The organic matter- and uranium-rich Tremadocian Koporie Formation (“Dictyonema Shale” as traditional informal unit; 6-14 wt. % TOC, 74-274 ppm uranium) was studied with respect to the spatial and temporal distribution of the uranium contents in the shale since deposition. It was the aim to unravel organic-inorganic interactions as results of α-particle irradiation due to the decay of 238U and the consequences for the differential alteration of the organic matter and petroleum potential.A multi-method approach was applied to gain data on high resolution from electron microscopy, organic petrography, and organic and inorganic geochemistry about core samples from a borehole drilled 50 km southwest to St. Petersburg (Russia). The analytical results indicate that there were two sources of uranium. Bottom water anoxia promoted the reduction of soluble U(VI) from seawater (source 1) to U(IV) followed by adsorption in the sediment. This uranium portion is neither quantifiable on minerals nor on organic matter by EDX-SEM. Bottom water currents caused intercalations of coarser-grained intervals during deposition of the lower part of the Koporie Formation. These intervals include detrital uranium-rich apatite and zircon grains together with graptolite rhabdosomes which are also rich in uranium (source 2). Flushing of these permeable layers by meltwater during the Pleistocene (de)glaciation caused mobilization of U(VI) due to oxidation of formerly adsorbed quadrivalent uranium. The present uranium contents in the lower Koporie Formationare thus residues of formerly higher contents and indicate that stronger irradiation-induced destruction of the organic matter occurred during higher uranium contents before meltwater leaching during the Pleistocene. Today the organic matter of the lower part exhibits characteristics of a kerogen type III from the perspective of pyrolytic products with a rather Gas and Condensate potential whereas the upper part of the Koporie Formationstill has the inherited signal of a kerogen type I/II with a Low-Wax Paraffinic Oil potential. Lithological and mineralogical heterogeneities in the lower part with locally strong irradiation are an alternative explanation for the stronger organic matter alteration.
14145. 题目: Rare Earth Elements in early-diagenetic foraminifer ‘coatings’: pore-water controls and potential palaeoceanographic applications
期刊: Geochimica et Cosmochimica Acta
作者: L.C. Skinner, A. Sadekov, M. Brandon, M.Greaves, Y. Plancherel, M. de la Fuente, J. Gottschalk, S. Souanef-Ureta, D.S. Sevilgen, A.E. Scrivner
摘要: Rare Earth Element (REE) distributions in the ocean bear the fingerprints of several key environmental processes, including vertical particle/organic carbon fluxes, water column/pore-water oxygenation and ocean transports. The use of ‘fossil’ REE analyses in the service of palaeoceanography as redox, water transport or nutrient cycling ‘proxies’ has long been a tantalizing possibility. Here we demonstrate the application of a novel laser-ablation microanalysis approach for the rapid and accurate measurement of the REE composition of early diagenetic ‘coatings’ on fossil foraminifera. By applying this new method to a range of core-top and multi-core samples, we show that ‘authigenic’ REE enrichments on planktonic foraminifer surfaces (REEfs) reflect a primary seawater signature that becomes overprinted during sediment burial due to early diagenetic processes that control the flux of REEs to pore-fluids. Thus ‘light’ REEs (LREEs), and eventually ‘middle’ REEs (MREEs) are generally enriched in foraminifer 'coatings' relative to seawater, while Ce-anomalies (Ce/Ce*) recorded in surface sediments are typically more positive than local seawater values and are further ‘eroded’ during burial with the onset of anoxic conditions in the sediment. Similar patterns have previously been observed in pore-fluid measurements. Indeed, we show that Mn and Fe concentrations measured in foraminifer ‘coatings’ track the availability of these elements in pore-water, indicating that they are not associated with a secondary oxide phase. We propose that these elements, along with REEs are instead adsorbed directly from pore-fluids. In contrast, U in authigenic coatings tracks the removal of this element from solution under sub-oxic conditions, supporting the use of U/Ca in foraminifer coatings as a redox proxy. Although our results confirm a significant early diagenetic influence on REEfs, we also demonstrate the potential utility of ‘Ce-enrichment’ relative to expected seawater values as a palaeo-oxygenation proxy. We support this proposal with down-core measurements of U/Ca and Ce-enrichment spanning the last deglaciation in the sub-Antarctic Atlantic, as well as a global array of LGM measurements, which are found to co-vary with parallel estimates of radiocarbon ventilation age, consistent with a widespread increase in the efficiency of the biological pump. Our results suggest that laser-ablation REEfs measurements may hold some promise for palaeoceanographic reconstruction, in particular through a shift in emphasis away from the reconstruction of primary seawater signals to the analysis of diagenetic impacts that are sensitive to changing hydrographic conditions.
14146. 题目: Reactive carbon and nitrogen concentrations and dynamics in groundwater beneath an earthen-lined integrated constructed wetland
期刊: Ecological Engineering
作者: M.M.R. Jahangir, Owen Fenton, Eoin McAleer, Paul Johnston, Rory Harrington, Christoph Müller, Karl G. Richards
摘要: Using earthen liners at the base of an integrated constructed wetland (ICW) maintains a hydraulic continuum between the ICW and the underlying groundwater body. This may enable migration of reactive carbon (dissolved organic and inorganic carbon (DOC, DIC)) and reactive nitrogen (Nr) across this liner to groundwater along this continuum to groundwater. Therefore, in terms of a holistic assessment of ICWs, quantification of these losses is important and indeed from an environmental perspective comparing such losses to other ICW dis-connected areas within the same groundwater body is critical. The main objective of the present study on an ICW site in SE Ireland was to compare reactive forms of C and N in groundwater (three piezometer nests) representing the continuum end point of ICW Cell 2 and 3 with that of groundwater dis-connected to the ICW system. For this purpose two control planes consisting of shallow and deep groundwater piezometer nests were installed and monitored at 1 and 4 m depths, respectively underneath the earthen liners at 0.2 m adjacent to the ICW cells. Fieldwork was conducted between Nov 2013 and Nov 2014 and results showed that groundwater beneath the ICW liner had a highly reduced signal with C and N concentrations being significantly higher to those of the disconnected up-gradient groundwater. The DOC, DIC and dissolved CO2 and CH4 concentrations in groundwater beneath the ICW cells were significantly higher than the up-gradient groundwater. All the reactive forms of C were higher in Cell 2 than in Cell 3. With respect to depth, all forms of reactive C were higher in deeper groundwater than the shallow equivalents except for DOC. Equally, Nr concentrations (NH4+, DON, NO3−-N and N2O) were higher in groundwater beneath the ICW cells than the up-gradient groundwater. They were higher in Cell 2 than in Cell 3 and higher in shallow rather than deep groundwater. The fate of the reactive C and N is unknown. Typically DOC delivery from groundwater to surface water drives many biogeochemical processes as an electron donor to microbes or can be converted to CO2 and CH4 emissions and the dissolved CO2 and CH4 can be indirectly exchanged to the atmosphere. The results suggest that nutrient delivery from the ICW cells to the underlying groundwater needs to be evaluated and the design of earthen-lined ICWs should consider this nutrient loss continuum across the liner.
14147. 题目: Relating soil C and organic matter fractions to soil structural stability
作者: Johannes L. Jensen, Per Schjønning, Christopher W. Watts, Bent T. Christensen, Clément Peltre, Lars J. Munkholm
摘要: Soil organic matter (SOM) is important for maintaining soil structural stability (SSS). This study quantified the influence of soil organic carbon (SOC) and different organic matter components on various SSS measures. We used a silt loam soil with a wide range of SOC (8.0–42.7 g kg−1 minerals) sampled in spring 2015 from the Highfield Ley-Arable Long-Term Experiment at Rothamsted Research. Four treatments were sampled: Bare fallow, continuous arable rotation, ley-arable rotation, and grass. Soils were tested for clay dispersibility (DispClay), clay-SOM disintegration (DI, the ratio between clay content without and with SOM removal) and dispersion of particles <20 μm. The SSS tests were related to SOC, permanganate oxidizable carbon (POXC), hot water-extractable carbon (HWC), mid-infrared photoacoustic spectroscopy (FTIR-PAS) and mineral fines/SOC ratio. SSS increased with increasing content of SOM components. The relationships between SOM components and SSS followed a broken-stick regression with a change point at ~23.0 g SOC kg−1 minerals (clay/SOC~10) coinciding with a change from the tilled treatments to the grass treatment. We found a greater influence of SOC, POXC and HWC on SSS at contents below the change point than above. A stronger linear relation between POXC and DispClay compared to SOC and HWC suggests that POXC was a better predictor of the variation in DispClay. POXC and HWC were less related to DI than SOC. The grass treatment had a very stable structure, shown in all SSS tests, probably due to the absence of tillage and large annual inputs of stabilizing agents. This suggests that a change in management from arable rotation to permanent grass is one effective tool for improving SSS.
14148. 题目: Impact of Antarctic climate during the Late Quaternary: Records from Zub Lake sedimentary archives from Schirmacher Hills, East Antarctica
期刊: Palaeogeography, Palaeoclimatology, Palaeoecology
作者: Badanal SiddaiahMahesh, Anish Kumar Warrier, Rahul Mohan, Manish Tiwari
摘要: The Antarctic continental margin is marked with ice-free areas which are host to numerous freshwater lakes. These lacustrine systems are rich in sedimentary deposits which archive in them the regional and general climatic variations. These lakes respond to the seasonal variations in climate over glacial-interglacial timescales and can be inferred from the sedimentary proxies. In this study, a 79-cm-long radiocarbon dated sediment core retrieved from a peri-glacial lake is analysed for elementary (Corg%, Norg%), isotopic (δ13COM, δ15NOM) and particle size (sand, silt, clay). The radiocarbon dated sections (0–65 cm) extends up to 43 kyr BP. The time-series of sedimentary organic matter (OM) proxies (Corg ~ 3.5 ± 3%, C/Natomic ratio ~ 11 ± 3 and δ13COM ~ −14 ± 4‰) indicate that the OM in this lake sedimentary record is an admixture of terrestrial and lacustrine biomass. Distinctly higher (lower) values during the Holocene (LGM) suggests presence of terrestrial and aquatic (aquatic) biomass indicating ice-free (ice-cover) and warm (cold) Holocene (glacial) conditions which would result in an increased (decreased) lake-productivity and fluvial (wind) input of sand and clay (silt). Higher sand content (~30, ~24 and ~15 kyr BP), silt content (~24 kyr BP), Corg and Norg (~24 kyr BP) within the Last Glacial Stage (LGS) indicates intermittent warming period in coherence with the Antarctic Isotope Maximum (AIM). The transition in values (Corg, Norg, C/N ratio, δ13COM, sand content) starting at 16.6 kyr BP closely following Antarctic deglaciation to reach Holocene optimum values at 11.3 kyr BP documents the influence of Antarctic climate on regional areas.
14149. 题目: Valuable polar moieties on cereal-derived biochars
期刊: Colloids and Surfaces A: Physicochemical and Engineering Aspects
作者: Magda Caban, Agnieszka Folentarska, Hanna Lis, Paulina Kobylis, Jolanta Kumirska, Piotr Stepnowski, Wojciech Ciesielski
摘要: The application of biochar (BC) in various fields of engineering, agriculture and environmental protection demands the task-specific adjustment of the surface characteristics of the carbon material. Polar moieties are those elements which distinguish BC from regular carbon black. The knowledge of polar moieties on the surface of the BC is crucial for its application for polar pollutants removal and resistance of nutrients. In this paper several techniques were applied for the verification of polar moieties of crop-derived biochars (both straw and grain) by several techniques (SBET, FTIR, SEM, EDS, pHPZC, elemental analysis). The characterization was also made for washed BCs. It was found that this carbon material is rich in polar moieties, mostly hydroxyl groups and oxides, the latter being washed away together with salts. The high oxygen content decreased after washing (> 15 %). The values of pHZPC do not differ between the tested BCs, were in the range of 2.2 to 2.0, and were not changed after the washing of BCs. Thanks to the SBET isotherm analysis, irreversible changes in the material structure by water adsorption were proven. The oxygen content in the surface of BCs can be changed after a very brief time of exposition to natural water or soil with no change in the surface charge. Still, the biochar derived from cereals is a useful material for application in environmental protection purposes.
14150. 题目: Initial insights into releasing bound biomarkers from kerogen matrices using microscale sealed vessel catalytic hydrogenation (MSSV-HY)
期刊: Organic Geochemistry
作者: Liangliang Wu, Brian Horsfield
摘要: Microscale Sealed Vessel pyrolysis (MSSV) is a microanalytical technique originally developed for artificially maturing sedimentary organic matter and examining the bulk compositional relationships between kerogen and petroleum. Here, we explore the possibility of modifying the standard MSSV pyrolysis approach to increase biomarker release from macromolecular matrices. This is termed microscale sealed vessel catalytic hydrogenation, or MSSV-HY. Tetralin is employed as hydrogen donor and dispersed sulfide molybdenum as catalyst. Using two kerogen concentrates, one of low maturity (vitrinite reflectance: 0.6 %Ro) and the other over-mature (1.8 %Ro), from the Dalong Mudstone (Permian, Sichuan Basin), the effects of tetralin and catalyst alone and as mixtures, and the tetralin/kerogen ratio on biomarker release have been investigated, and optimum conditions identified. A comparison of results with those of HyPy enabled the utility of the method to be assessed. Biomarkers were generated from the over-mature sample and preserved using MSSV-HY, whereas they were absent in MSSV products. Biomarkers released from the low maturity sample using MSSV were devoid of extended hopanes, and dominated by C27 steranes, whereas the MSSV-HY products were rich in Tm, the extended hopanes, and with C27–C29 regular steranes. MSSV-HY products showed some similarities to HyPy products. The steranes from MSSV-HY were very similar to those from HyPy; although some differences in hopane distributions were discernable (e.g., the abundances of Ts and C30 hopane) due to varied contribution of occluded OM in the HyPy and MSSV-HY analyses. This proof of concept study has shown that off-line MSSV-HY shows great promise as a means for releasing bound biomarkers and reducing secondary cracking because of catalyst associated pressure increase in the MSSV tubes. Its currently planned area of operation is in petroleum systems.
14151. 题目: Geochemical and petrographic evidence for the co-occurrence of races B and L of Botryococcus braunii in the Maoming oil shales, China
期刊: Organic Geochemistry
作者: Hong Lu, Yujiao Zhang, Qiao Feng, Liming Ji, Mingzhen Zhang, Ping'an Peng, Guoying Sheng, Dehan Liu
摘要: Around 30 Maoming oil shale samples were collected and analyzed geochemically to investigate their biomarker compositions. C31 and C33 botryococcanes were abundant in some samples whilst high contents of lycopanes (C39 and C40) and a monoaromatic lycopane derivative with concomitant occurrence of botryococcanes were also detected in other samples. These indicate that the fossils of the races B and L of Botryococcus braunii co-exist in the Maoming sediments thus providing an excellent opportunity to explore the morphological differences of two races of B. braunii. Different preparation and observation methods were carried out for better and detailed morphological observations enabling the fossil characters between race B and L of B. braunii to be recognized. Better observations were obtained using white fluorescence transmitted light under UV-induced fluorescence microscopy because yellow fluorescence was avoided. Race B of B. braunii has polygonal cup mouths and is often covered by an envelope. However, race L has a relatively smaller colony size and round cup mouth. The co-occurrence of race B and L of B. braunii in Maoming sediments possibly implies a tropical to subtropical climate during the Late Eocene–Oligocene period in the study area.
14152. 题目: Determining the influence factors of soil organic carbon stock in opencast coal-mine dumps based on complex network theory
作者: Zhaotong Zhang, Jinman Wang, Bo Li
摘要: The soil organic carbon (SOC) stock is severely affected by the exploitation of opencast coal mines, and the relationships of factors influencing SOC stock are complex. The influence factors of SOC stock in reclaimed lands in opencast coal mines are unclear, and the existing models can not characterize the complex relationship of SOC stock sufficiently. This paper analyzed the influence factors of SOC stock using complex network theory in the Antaibao opencast coal-mine in Shanxi province of China. An investigation of the soil, topography and vegetation in 50 reclaimed plots was performed. Soil factors, i.e., rock content (RC), total nitrogen (TN), available phosphorus (AP), available potassium (AK), soil bulk density (BD), soil water content (SWC), SOC stock, electrical conductivity (EC), clay content, silt content, sand content and pH, vegetation factors, i.e., above-ground biomass (AGB), tree volume (TV), herb coverage (HC), canopy density (CD), and topography factors, i.e., slope, slope aspect (SA) and slope position (SP), were selected as the nodes, and the relationship among the various factors were considered as the edges to construct a complex network using Gephi. The network characteristics, including degree, betweenness and average shortest path so on, were calculated. SOC stock, SWC and BD played an important role in the complex network of SOC stock. The SOC stock was affected by three clusters: soil texture cluster, soil physicochemical property cluster, and vegetation-topography cluster. SOC stock network was not stable and was sensitive when some important nodes were disturbed. The complex network theory could be used to analyze the influence factors of SOC stock. This study provided a reference for selecting rational land reclamation measures to increase soil carbon stock.
14153. 题目: Removal of hexavalent chromium by biochar supported nZVI composite: Batch and fixed-bed column evaluations, mechanisms, and secondary contamination prevention
作者: Zixi Fan, Qian Zhang, Bin Gao, Meng Li, Chaoying Liu, Yue Qiu
摘要: Conversion of carcinogenic Cr(VI) to less toxic Cr(III) has long been regarded as the most efficient and effective method to remediate Cr(VI)-contaminated water. However, the widely used reducing agents such as nano zero-valent iron (nZVI) and its derivatives often have low stability and their applications in water treatment may introduce secondary contaminations. To shed light on these, nZVI was loaded on sludge derived biochar to produce nZVI-BC composite for Cr(VI) removal. Batch experiments showed that Cr(VI) adsorption on nZVI-BC was endothermic and highly pH dependent. The adsorption kinetic and isotherm data were described by the pseudo second-order kinetic model and the Langmuir isotherm model, respectively. The removal of Cr(VI) by nZVI-BC was mainly through reduction-adsorption. After the experiment, nZVI-BC was transformed into a stable magnetic adsorbent that can be magnetically separated from aqueous phase during first circle application. In fix-bed columns, nZVI-BC also effectively removed Cr(VI) under various operation conditions and the Thomas and Yoon-Nelson models described the experimental breakthrough curves well. The post-adsorption nZVI-BC was re-pyrolyzed, which stabilized and reduced the bioavailability of Cr in the biochar. Re-pyrolysis thus can be used as an effective technology to reduce the environmental risks of post-adsorbent biochar for safe disposal.
14154. 题目: Surface coating of UF membranes to improve antifouling properties: a comparison study between cellulose nanocrystals (CNCs) and cellulose nanofibrils (CNFs)
作者: Langming Bai, Yatao Liu, An Ding, Nanqi Ren, Guibai Li, Heng Liang
摘要: The inherent properties of hydrophilicity and environmental preferability of cellulose nanocrystals (CNCs) and cellulose nanofibers (CNFs) make them great candidates for application in water-treatment membranes. In this study, the antifouling properties of CNCs and CNFs, modified ultrafiltration (UF) membranes, were directly compared. A facile modification method was conducted by coating CNCs and CNFs on the surface of polyethersulfone (PES) membranes to prepare CNC-coating membranes and the CNF-coating membranes. Membrane surface morphology was characterized by atomic force microscopy (AFM), and the results showed that the CNF-coating membranes exhibited greater surface roughness than the CNC-coating membranes. Pure water flux measurements demonstrated that the flux of the CNC-coating membranes was slightly lower than that of the CNF-coating membranes. Antifouling properties were evaluated and compared for the two types of membranes by filtration of NOM foulant models, humic acid (HA) and bovine serum albumin (BSA). The results showed that the antifouling properties of the modified membranes were enhanced through the coating of either CNCs or CNFs to a control PES membrane. The CNC-coating membranes outperformed the CNF-coating membranes in alleviating both reversible fouling and irreversible fouling caused by HA and BSA. In addition, the antifouling performance of the coating membranes was enhanced with increased coating content.
14155. 题目: Effect of soil properties on Pb bioavailability and toxicity to the soil invertebrate Enchytraeus crypticus
作者: Lulu Zhang, Rudo A. Verweij, Cornelis A.M. Van Gestel
摘要: The present study investigated the bioavailability and toxicity of lead to the potworm Enchytraeus crypticus in six soils with different properties. Pb partitioning between the soil solution and solid phase was affected by soil organic matter (OM) content, cation exchange capacity (CEC) and water holding capacity (WHC). After 21 d exposure, Pb bioaccumulation in the enchytraeids was positively correlated with total soil Pb concentration. Bioaccumulation was best predicted by Pb availability (CaCl2-extractable and porewater Pb concentrations), and by the Ca concentration in pore water and the CEC of the soils. Toxicity varied greatly among soils, with LC50s and EC50reproductions based on total Pb concentrations ranging from 246 to >3092 and from 81 to 1008 mg Pb/kg dry soil, respectively. The variation in LC50s among soils was explained by differences in CaCl2-extractable Pb concentrations in soil and internal Pb concentrations in the animals. The differences in EC50reproductions could be explained from the CaCl2-extractable Pb concentrations in the soils. Although it was also correlated with CEC and porewater Ca concentration, pHCaCl2 was the dominating factor for predicting Pb toxicity based on total soil concentrations. This study demonstrates that soil properties, such as pH, CEC and Ca concentration in pore water, significantly affected the bioavailability and toxicity of Pb and therefore should be taken into account when assessing the ecological risk of metals in contaminated soils.
14156. 题目: Accumulation of perfluorinated alkyl substances (PFAS) in agricultural plants: a review
期刊: Environmental Research
作者: Rossella Ghisi, Teofilo Vamerali, Sergio Manzetti
摘要: PFASs are a class of compounds that include perfluoroalkyl and polyfluoroalkyl substances, some of the most persistent pollutants still allowed - or only partially restricted - in several product fabrications and industrial applications worldwide. PFASs have been shown to interact with blood proteins and are suspected of causing a number of pathological responses, including cancer. Given this threat to living organisms, we carried out a broad review of possible sources of PFASs and their potential accumulation in agricultural plants, from where they can transfer to humans through the food chain. Analysis of the literature indicates a direct correlation between PFAS concentrations in soil and bioaccumulation in plants. Furthermore, plant uptake largely changes with chain length, functional group, plant species and organ. Low accumulations of perfluorooctanoic acid (PFOA) and perfluorooctane sulfonic acid (PFOS) have been found in peeled potatoes and cereal seeds, while short-chain compounds can accumulate at high levels in leafy vegetables and fruits. Significant variations in PFAS buildup in plants according to soil amendment are also found, suggesting a particular interaction with soil organic matter. Here, we identify a series of challenges that PFASs pose to the development of a safe agriculture for future generations.
14157. 题目: In-situ remediation of hexavalent chromium contaminated groundwater and saturated soil using stabilized iron sulfide nanoparticles
期刊: Journal of Environmental Management
作者: Tao Wang, Yuanyuan Liu, Jiajia Wang, Xizhi Wang, Bin Liu, Yingxu Wang
摘要: Hexavalent chromium (Cr(VI)) is one of prevalent toxic and mobile heavy metal contaminants in the environment. In this study, synthetic iron sulfide nanoparticles (FeS NPs) stabilized with carboxymethyl cellulose (CMC) were applied to remediate Cr(VI) contaminated groundwater and saturated soil. The batch test results showed that aqueous Cr(VI) was removed with a capacity as high as 1046.1 mg Cr(VI) per gram of FeS NPs. The removal of aqueous Cr(VI) mainly involves adsorption, reduction and co-precipitation. Aqueous Cr(VI) removal by using FeS NPs was a strong pH-dependent process. Dissolved oxygen (DO) would compete with Cr(VI) for Fe(II) and S(-II) and inhibit the process of Cr(VI) reduction at pH 5.6. For ionic strength and natural organic matter (NOM), there were no significant influences on the aqueous Cr(VI) removal. Column tests demonstrated that the concentrations of Cr(VI) in the effluent were lower than 0.005 mg L−1 after an elution of 45 pore volumes (PVs) of stabilized FeS NPs suspension. The leached Cr(VI) decreased from 4.58 mg L−1 of raw Cr(VI)-contaminated soil to 46.8–80.7 μg L−1 from the surface to bottom treated soil in column through Toxicity Characteristic Leaching Procedure (TCLP). Therefore, the synthesized FeS NPs hold high potential for the in-situ remediation of Cr(VI)-contaminated groundwater and saturated soil.
14158. 题目: Biochar-mediated sorption of antibiotics in pig manure
期刊: Journal of Hazardous Materials
作者: A.N. Ngigi, Y.S. Ok, S. Thiele-Bruhn
摘要: Using manure contaminated with antibiotics as fertilizer is a primary source of soil pollution with antibiotics and concomitantly with antibiotic resistance genes (ARG). Bioavailable antibiotics trigger further ARG amplification during manure storage. Consequently it is aimed to facilitate the immobilization of antibiotics in manure. To this end, five biochars derived from pine cone (BCP), rice husk, sewage sludge, digestate and Miscanthus were tested as additional sorbents in liquid pig manure for sulfamethazine, ciprofloxacin, oxytetracycline and florfenicol. Non-linear sorption was best-fit using the Freundlich isotherm (R2 > 0.82) and the pseudo-second-order model best described sorption kinetics (R2 > 0.94). Antibiotics’ sorption onto manure increased in the order sulfamethazine < florfenicol < ciprofloxacin < oxytetracycline. Admixtures of BCP to manure changed the order to sulfamethazine < oxytetracycline < florfenicol = ciprofloxacin. Generally, with the addition of biochar, sorption coefficients of florfenicol increased most (by factors >2.7) followed by sulfamethazine and ciprofloxacin. Yet, oxytetracycline was mostly mobilized probably due to competitive adsorption. Effects depended on the proportion of biochar added and the type of biochar, whereby plant-derived biochar exhibited better immobilization of antibiotics. Depending on the type and portion of biochar, admixtures to manure can be used to lower the mobility and hence bioavailability of fenicols, fluoroquinolones and sulfonamides.
14159. 题目: Resistance and resilience of representative low nucleic acid-content bacteria to free chlorine exposure
期刊: Journal of Hazardous Materials
作者: Yuhao Song, Guannan Mao, Guanghai Gao, Mark Bartlam, Yingying Wang
摘要: Two representative low nucleic acid-content (LNA) bacterial strains, Polynucleobacter sp. CB and Sphingopyxis sp. 15Y-HN, and two commonly used microbial indicators of drinking water disinfection efficiency, Escherichia coli and Pseudomonas aeruginosa, were used to investigate the effects of chlorine disinfection. LNA bacteria were found to be more tolerant than microbial indicator strains at the same free chlorine concentrations in batch experiments. Three-stage chlorination experiments were carried out for two strains (15Y-HN and E. coli K12) to compare their responses to long-term chlorine exposure. Results from the first stage (increasing chlorine exposure) showed the rate constants of 99% cell damage were 10-fold higher for strain 15Y-HN than for strain K12. A second regrowth stage at low free chlorine concentrations (< 0.3 mg/L) facilitated the regrowth of chlorine-resistant populations of strains 15Y-HN and K12 in the presence of assimilable organic carbon (AOC). In the third stage, during which bacteria were exposed to increasing chlorine, strain 15Y-HN was maintained at 80% and 105 cells/mL of intact cells whereas strain K12 was completely damaged. The overall results demonstrated that representative LNA bacteria exhibit strong resistance and resilience to chlorine under low AOC conditions, which should be taken into consideration in disinfection processes.
14160. 题目: Biochar combined with polyvalent phage therapy to mitigate antibiotic resistance pathogenic bacteria vertical transfer risk in an undisturbed soil column system
期刊: Journal of Hazardous Materials
作者: Mingming Sun, Mao Ye, Zhongyun Zhang, Shengtian Zhang, Yuanchao Zhao, Shaopo Deng, Lingya Kong, Rongorng Ying, Bing Xia, Wentao Jiao, Jiaqi Cheng, Yanfang Feng, Manqiang Liu, Feng Hu
摘要: The vertical migration of antibiotic resistance pathogenic bacteria (ARPB) and antibiotic resistance genes (ARGs) in the surface soil-vadose soil system has become a new threat to ecological safety and public health; there is an imperative need to develop an efficient technique for targeted control and inactivation of ARPB in these systems. In this work, undisturbed soil columns (0 ∼ −5 m) were constructed to investigate the impact of biochar amendment or/and polyvalent bacteriophage (ΦYSZ-KK) therapy on the vertical control and inactivation of tetracycline-resistant Escherichia coli K-12 and chloramphenicol-resistant Klebsiella pneumonia K-6. The simultaneous application of polyvalent phage and biochar impeded the vertical migration of ARPB from the top soil to lower soil layers and stimulated the ARPB dissipation in the soil column. After 60-day incubation, levels of ARPB and ARGs decreased significantly in the soil column by magnitudes of 2-6. Additionally, high throughput sequencing indicated that the simultaneous application of biochar and phage clearly maintained the structure and diversity of the soil microbial communities (p < 0.05). This work therefore demonstrates that the application of a biochar/phage combination is an environmentally friendly, efficacious measure for the control and inactivation of ARPB/ARGs in vertical soil column systems.