181. 题目: Adsorption of flupyradifurone onto soils: Kinetics, isotherms, and influencing factors
182. 题目: In-situ formation of surface reactive oxygen species on defective sites over N-doped biochar in catalytic ozonation
Adsorption is the first step of the interface mechanism, but the adsorption behaviors of ozone (O3) and pollutants on the catalyst during catalytic ozonation have always been overlooked in previous works. In this study, a promising strategy for the in-situ decomposition of O3 to trigger surface reactive oxygen species (ROS) by nitrogen (N)-doped biochar was proposed, which greatly improved the efficiency of O3 utilization. Specifically, N-doped biochar (NBC700) with a high defect level (ID/IG = 1.165) was achieved by a one-pot method. It showed good adsorption on O3 and atrazine (ATZ), which promoted the in-situ formation of surface ROS, as well as resists the interferences of multiple coexisting anions (NO3−, Cl−, PO43−, SO42− and HCO3−) on ATZ removal. In-situ Raman spectra revealed the interface catalytic mechanism of O3 decomposition into adsorbed peroxide species (*O2) and adsorbed atomic oxygen (*O). Additionally, OH was the dominant ROS and surface-O3 further strengthened direct ozonation via intramolecular electron transfer. In this process, sp2-hybridized system with delocalized π electrons, electron-rich oxygen-containing functional groups, and conjugated heteroatoms were identified as the active sites, but defective sites with free electrons played the most important part according to the lowest adsorption energy (−13.12 eV) calculated by density functional theory (DFT). The degradation of ATZ included dechlorination and non-dechlorination pathways, which made the acute and chronic toxicity of most intermediate products both decrease to not be harmful to fish and green algae. This work provides a new perspective on the interface mechanism in catalytic ozonation for ATZ removal.
183. 题目: Improving soil organic carbon predictions from a Sentinel–2 soil composite by assessing surface conditions and uncertainties
Soil organic carbon (SOC) prediction from remote sensing is often hindered by disturbing factors at the soil surface, such as photosynthetic active and non–photosynthetic active vegetation, variation in soil moisture or surface roughness. With the increasing amount of freely available satellite data, recent studies have focused on stabilizing the soil reflectance by building reflectance composites using time series of images. Although composite imagery has demonstrated its potential in SOC prediction, it is still not well established if the resulting composite spectra mirror the reflectance fingerprint of the optimal conditions to predict topsoil properties (i.e. a smooth, dry and bare soil).
We have collected 303 photos of soil surfaces in the Belgian loam belt where five main classes of surface conditions were distinguished: smooth seeded soils, soil crusts, partial cover by a growing crop, moist soils and crop residue cover. Reflectance spectra were then extracted from the Sentinel–2 images coinciding with the date of the photos. After the growing crop was removed by an NDVI < 0.25, the Normalized Burn Ratio (NBR2) was calculated to characterize the soil surface, and a threshold of NBR2 < 0.05 was found to be able to separate dry bare soils from soils in unfavorable conditions i.e. wet soils and soils covered by crop residues. Additionally, we found that normalizing the spectra (i.e. dividing the reflectance of each band by the mean reflectance of all spectral bands) allows for cancelling the albedo shift between soil crusts and smooth soils in seed–bed conditions. We then built the exposed soil composite from Sentinel–2 imagery for southern Belgium and part of Noord-Holland and Flevoland in the Netherlands (covering the spring periods of 2016–2021). We used the mean spectra per pixel to predict SOC content by means of a Partial Least Squares Regression Model (PLSR) with 10–fold cross–validation. The uncertainty of the models was assessed via the prediction interval ratio (PIR). The cross validation of the model gave satisfactory results (mean of 100 bootstraps: model efficiency coefficient (MEC) = 0.48 ± 0.07, RMSE = 3.5 ± 0.3 g C kg–1, RPD = 1.4 ± 0.1 and RPIQ = 1.9 ± 0.3). The resulting SOC prediction maps show that the uncertainty of prediction decreases when the number of scenes per pixel increases, and reaches a minimum when at least six scenes per pixel are used (mean PIR of all pixels is 12.4 g C kg–1, while mean SOC predicted is 14.1 g C kg–1). The results of a validation against an independent data set showed a median difference of 0.5 g C kg–1 ± 2.8 g C kg–1 SOC between the measured (average SOC content 13.5 g C kg–1) and predicted SOC contents at field scale. Overall, this compositing method shows both realistic within field and regional SOC patterns.
184. 题目: Effects of PFOS at ng/L levels on photostability of extracellular polymeric substances under solar irradiation by fluorescence and infrared spectroscopy
The ubiquitous EPS (extracellular polymeric substances), as a type of dissolved organic carbon, plays a key role in carbon cycling in water environment. When EPS meet the omnipresent PFOS (perfluorooctane sulfonate), they must interact with each other and exert profound effect on behavior and fate of both, which is still not well known. We hypothesized that the highly persistent PFOS at real environmental levels may significantly influence behavior of EPS under solar irradiation which may retard carbon turnover. In this study, 3D-EEM fluorescence spectroscopy and FTIR spectroscopy were used to probe responses of composition and structure of EPS under solar irradiation in the absence and presence of PFOS (5–500 ng/L). The experimental results showed that PFOS at ng/L levels significantly affected responses of EPS to sunlight irradiation and the effects were dependent on the components in EPS. Photostability of humic-like substances was significantly increased in the presence of PFOS; Degradation and unfolding of proteins induced by solar light were reduced by PFOS. In addition, degradation of both hydrophilic and hydrophobic functional groups by sunlight was inhibited by PFOS. The novel findings provide new insights for assessing the environmental behavior of EPS and PFOS and understanding the effect of PFOS on carbon cycling in water environments.
185. 题目: Arsenic speciation, oxidation and immobilization in an unsaturated soil in the presence of green synthesized iron oxide nanoparticles and humic acid
While the availability of arsenic (As) in soil is well known to be highly correlated with the presence of iron (Fe) oxides and humic acid (HA) in the soil, the relationship between Fe oxides and HA and As species in the soil is less well understood. In this study, As speciation in an unsaturated soil in the presence of external HA and green synthesized Fe oxide nanoparticles (FeNPs) showed that As(V) was mainly distributed to the specifically-bound (F2), amorphous and poorly-crystalline hydrous oxides of Fe, Al (F3) and the well-crystallized hydrous oxides of Fe and Al (F4). While As(III). This was the major component in unsaturated soil, and was mainly distributed to F4 and the residual fraction (F5). As bound to F3 and F5 was most sensitive to the addition of HA and FeNPs, while HA/FeNPs treatment increased the F3-bound As(V); however, it decreased the F5-bound As(III). Nonetheless the effect of HA on As is completely different to the HA/FeNPs treatment. The increase of As(V) in F3 resulted from F5-bound As(III) oxidation when treated by HA/FeNPs. Cyclic voltammetry confirmed that HA and Fe3+/Fe2+ redox enhanced As(III) oxidation, while FTIR revealed that HA-bound As(III) was the least available fraction in the soil. Finally, a mechanism involving a combination of HA and FeNPs was proposed for explaining the redistribution of As species in the soil.
186. 题目: The influence mechanism of hydrogeochemical environment and sulfur and nitrogen cycle on arsenic enrichment in groundwater: A case study of Hasuhai basin, China
Hydro-biogeochemical processes control the formation and evolution of high arsenic (As) groundwater. However, the effects of nitrogen and sulfur cycles in groundwater on As migration and transformation are not well understood. Thus, twenty-one groundwater samples were collected from the Hasuhai basin. Hydrochemistry and geochemical modeling were used to analyze the geochemical processes associated with nitrogen and sulfur cycles. An arsenic speciation model (AM) and a sulfide-As model (SAM) were constructed to verify the existence of As species and the formation mechanism of thioarsenate. A hydrous ferric oxide (Hfo)-As adsorption model (HAM) and a competitive adsorption model (CAM) were used to reveal the adsorption and desorption mechanisms of As. The results showed that high arsenic groundwater (As > 10 μg/L) was mainly distributed under reductive conditions, and the highest concentration was 231.5 μg/L. The modeling results revealed that sulfides were widely involved in the geochemical cycle of As, with H3AsO3 and H2AsO3− accounting for >70 % of the total As, and thioarsenate accounting for 30 %. S/As < 2.5 and S/Fe < l control the formation of thioarsenate. With the high correlation of NH4+, TFe, sulfide, and TAs, the co-mobilization of N and S cycles may facilitate As enrichment in groundwater. A weak alkaline reduction environment triggered by the decomposition of organic matter was the main factor leading to the transfer of As from the aquifer to the groundwater. This research contributes to the development of high-As groundwater, and the findings are of general significance for drinking water in the Hasuhai Basin.
187. 题目: Peroxymonosulfate activation through magnetic Fe3C/Fe doped biochar from natural loofah sponges for carbamazepine degradation
Taking advantage of the unique properties of the channel structure of loofah, a series of three-dimensional (3D) magnetic Fe3C/Fe-doped biochar was prepared by simple and feasible pyrolysis of the mixture of raw loofah sponges and FeCl3·6H2O, and used as the functional activator of peroxymonosulfate (PMS) for carbamazepine (CBZ) removal. The optimized 0.5Fe@LSBC800 showed the optimum catalytic activity and almost complete CBZ was removed in the 0.5Fe@LSBC800/PMS system within 30 min, which was significantly higher than that of Fe0/PMS (44%), Fe3O4/PMS (17%), and Fe3C/PMS (45%) systems due to the synergistic effect between the doped Fe species and 3D biochar with abundant nucleophilic groups (-OH) and electrophilic groups (C=O). Furthermore, the possible catalytic mechanism of PMS activation by 0.5Fe@LSBC800 was proposed based on the comprehensive characterization analysis, chemical probe experiments, and electron paramagnetic resonance test. The CBZ degradation pathways in the 0.5Fe@LSBC800/PMS system were proposed according to the detected degradation intermediates, and the ecotoxicity of CBZ and its by-products was evaluated. At last, the practical application potential of the 0.5Fe@LSBC800/PMS system was evaluated.
188. 题目: Experimental Insight into the Enigmatic Persistence of Marine Refractory Dissolved Organic Matter
189. 题目: Applying EEM-PARAFAC combined with moving-window 2DCOS and structural equation modeling to characterize binding properties of Cu (II) with DOM from different sources in an urbanized river
Dissolved organic matter (DOM) in aquatic environment distinctly affects the behavior and fate of heavy metals via complexation, while the interfacial mechanisms and processes are still lacking in detail. Here, Cu (II) binding characteristics of DOM originated from hilly (NDOM), rural (RDOM) and urban (UDOM) regions in an urbanized river was explored by fluorescence excitation-emission matrix spectroscopy (EEM) combined with principal component coefficients, parallel factor analyses (PARAFAC), moving-window two-dimensional correlation spectroscopy (MW2DCOS) and structural equation modeling (SEM). Eight components were extracted from the titrants through EEM-PARAFAC, i.e., phenol-like substance (C1), tyrosine-like substance (C2), visible tryptophan-like substance (C3), ultraviolet tryptophan-like substance (C4), recent biological production (C5), wastewater-derived organic matter (C6), microbial humic-like substance (C7) and fulvic-like substance (C8). Interestingly, NDOM only contained C1, C3, C5 and C8, while nearly all components were found in RDOM (except for C2) and UDOM (except for C4). The f value of C1 (1.239) in NDOM was much higher than those in RDOM (0.134) and UDOM (0.115), so was of C8. It indicated that phenol-like and fulvic-like derived from autochthonous sources exhibited great binding ratios in the complexation with Cu (II). Moreover, C3 and C5 from UDOM exhibited higher f values (0.591 and 1.983) than those from NDOM and RDOM, suggesting that Cu (II) has a great binding capacity on protein-like from domestic and industrial wastewater. The MW2DCOS revealed that phenol-like and protein-like in NDOM and RDOM were essential for the binding of 160 μmol L−1 Cu (II), whereas fulvic-like in NDOM and UDOM could react significantly with 10 μmol L−1 Cu (II). Based on SEM, Cu (II) concentration had a negative direct effect on the fluorescence intensity of C7 or C8, whereas it showed an indirect positive effect on C7 or C8 through influencing C5, so was C6. It suggested that Cu (II) showed an indirect positive effect on the C8. This study might present a further comprehend of the environmental behaviors of Cu (II) in rivers.
190. 题目: Boron doped diamond electro-oxidation coupled with ultrafiltration for Microcystis aeruginosa and Microcystins removal in offshore environment: the significance of in-situ generation of chloramine and membrane fouling mitigation
Algae blooms and toxins pose a serious threat to the ecological security and human health in coastal areas. Coupling electro-oxidation with ultrafiltration is an effective means of treating algae-laden water. This study was designed to assess the removal of Microcystis aeruginosa and Microcystins in the offshore environment using a hybrid system combining BDD electro-oxidation with ultrafiltration. The results show that under suitable conditions, electro-oxidation rapidly inactivated algal cells and completely removed chlorophyll from the algae-laden water. In addition, electro-oxidation was effective in degrading microcystin-LR and dissolved organic carbon, with 83% and 66% removals observed within 30 minutes, respectively. The system also reduced the concentrations of proteins and humic acids partly, while converting large molecules to small molecules and increasing the proportion of hydrophilic substances. A large amount of free chlorine was generated and most of the ammonia nitrogen in the water was converted to nitrogen and chloramine during the oxidation process. The electro-oxidation exhibited a better performance in treating algae in the growth phase than in the decline phase. During long-term operation, the hybrid system showed stable removal of chlorophyll, turbidity, and UV254. Applying electro-oxidation treatment prior to ultrafiltration led to slower transmembrane pressure (TMP) increase rate in the course of the experiment. The SEM results suggest that after moderate electro-oxidation, the algal cells formed a less compact fouling layers, which alleviated the ultrafiltration membrane fouling.
191. 题目: Composition, distribution, and source of organic carbon in surface sediments of Erhai Lake, China
Lake sediment is an important organic carbon (OC) sink. Nevertheless, few studies have been conducted on sediment organic carbon (SOC) in lakes, and the effects of environmental variables on SOC pools remain poorly understood. We combined physicochemical and spectroscopic analyses to investigate the composition, distribution, and source of OC in surface sediments of Erhai Lake, southwest China, and explored the relationships between environmental variables and its SOC pool. The SOC pool consists of relatively high proportions of labile organic carbon fractions, mainly from algal production, which are rapidly decomposed and exhibit high turnover rates. The relative content of humus carbon ranges from 13.5 % to 20.5 %, with fulvic acid carbon predominating (average 52.95 %), indicating weak humification and a relatively active humus carbon pool. The dissolved organic matter in water column and sediments of Erhai Lake is largely influenced by endogenous production, with a great contribution from phytoplankton. Surface sediments contained more protein-like components than overlying waters (80.0 % vs. 63.0 %), attributed mainly to abundant algal deposition and intense bacterial metabolism. Among environmental variables, sediment chlorophyll a showed the strongest relationship with the SOC pool, and was associated with rapid decomposition and promotion of the humification process, which supported the conclusion that algae had an important influence on the SOC pool. The SOC pool in the southern region of the lake is mainly contributed by algae, other microorganisms, and sewage, exhibiting a greater potential to release organic matters into the water column. The center and northern SOC pools show relatively stable characteristics and stronger OC sink capacity, mainly because of the input of terrestrial refractory organic matters from runoff. Our data shed light on the OC storage mechanisms in the surface sediments of Erhai Lake and provide theoretical bases for enhancing the OC sink of sediments in the lake.
192. 题目: Transfer organic chloramines to monochloramine using two-step chlorination: A method to inhibit N-DBPs formation in algae-containing water treatment
Organic chloramines formed in chlorination of algae-containing water are typical precursors of nitrogenous disinfection byproducts (N-DPBs). The objective to simultaneously enhance the removal efficiency of organic chloramines and control DBP formation remains a challenge. In this study, we report a two-step chlorination strategy for transferring organic chloramines to monochloramine based on the decomposition mechanisms of mono- and di-organic chloramines, which could limit organic chloramines formation and inhibit N-DBPs formation. We demonstrated that two-step chlorination could decrease the organic chloramines formation by nearly 50% than conventional one-step chlorination. Furthermore, two-step chlorination not only blocked the pathway that organic chloramines decomposed to nitriles, but also led to the conversion of organic chloramines to monochloramine. During two-step chlorination of algal organic matter, the organic chloramine transfer proportion decreased by 6.5% and the monochloramine transfer proportion increased by 17.0%. The N-DBP formation, especially haloacetonitriles (HANs), decreased significantly as organic nitrogen became inorganic nitrogen (monochloramine) in two-step chlorination. This work further clarified the process from algal organic matter to N-DBPs, which could expand our understanding of algae-derived organic chloramines removal and DBPs control.
193. 题目: Covalent immobilizing horseradish peroxidase on electrochemically-functionalized biochar for phenol removal
Enzyme-based biocatalytic treatment has been known as an effective measure to biologically degrade organic pollutants. Advantageously, enzymes could be immobilized on solid supports, and such fact enables reuse/prolong the enzymatic capability. It could be of great importance to functionalize a support material for enhancing the immobilization efficiency/stability of enzymes. As such, this study laid great emphasis on covalent bonding to immobilize horseradish peroxidase (HRP) on a functionalized rice straw biochar with glutaraldehyde (GA) as a crosslinker. Biochar was pretreated by the electrochemical method and the acid treatment respectively to enrich the oxygen-containing functional groups. These led to the enhanced immobilizing ability of biochar. The HRP immobilized on the electrochemically-functionalized biochar (HRP-EBC) showed three times as much enzyme activity as the HRP directly adsorbed onto biochar. The HRP immobilized on the acid-functionalized biochar (HRP-ABC) showed activity similar to that of HRP-EBC. It was concluded that both the (acid/electrochemical) pretreatments are effective to enhance enzyme immobilization. Nevertheless, the electrochemical functionalized method of biochar is chemical oxidant-free, and one important lesson from a series of tests was that the pretreatment of biochar through the electrochemical method could be more environmentally benign. Moreover, employing HRP-EBC could be beneficial from a perspective of a real environmental practice considering its higher pH, thermal stability, and good reusability. 80% of phenol was degraded in 1 h in the presence of HRP-EBC when pH was 7.0 and a ratio of H2O2 to phenol was 1:1.5.
194. 题目: Response of cadmium adsorption to three-year different agronomic managements in tropical soil: The role of P fractions and Fe oxides
The overuse of chemical fertilizers and intensive cropping systems often results in soil quality degradation in the tropical and subtropical regions and affects cadmium (Cd) availability to crops. Therefore, studying the impact of agronomic managements on soil Cd adsorption and related mechanisms is critical for sustainable agriculture in tropical regions. Here, a three-year field experiment was conducted with five different agronomic managements [corn-pepper rotation with NPK fertilizers as control treatment (NPK), corn-pepper rotation with NPK fertilizers and sheep manure (NPKM), continuous corn cropping (CC), corn-pepper intercropping, and then rotation with green manure (CPGM), and corn-pepper rotation and then fallow (CPRF)]. The chemical characterization of bulk soils and soil aggregates from different treatments was performed and the isotherm adsorption experiments of Cd on different bulk soils and soil aggregates were conducted to investigate the effects of agronomic managements on characters of bulk soil and soil aggregates and subsequent effects on Cd adsorption. The results revealed that the maximum adsorption of Cd by bulk soil and various soil aggregates in the five treatments ranged from 0.235 to 0.627 and 0.222–1.360 mg g−1, respectively. The change of maximum Cd adsorption with management was in the order of CPGM > CPPF > NPKM > CC > NPK, regardless of bulk soil and soil aggregates. Compared to the NPK treatments, total P and Fe contents were significantly increased in the bulk soil and various soil aggregates of the CPGM and CPRF treatments, respectively. Furthermore, SEM-EDS analysis implied that the micro-zone distribution of Cd in the bulk soil was closely related to P and Fe, especially in the CPGM treatment. Random forest model revealed that soil pH predominantly contributed to the Cd adsorption by both the bulk soil (8.7%) and 0.25–2.0 mm soil aggregates (10.8%) in the five treatments. However, the contribution of humic P, amorphous Fe oxide, labile inorganic P, labile organic P, and total P were significantly higher than soil pH for 0.053–0.25 mm and < 0.053 mm soil aggregates. Overall, corn-pepper intercropping with green manure rotation was promising for Cd immobilization by tropical soil because of the increased effective contents of P fractions and Fe oxides for Cd adsorption.
195. 题目: Insights into enhanced removal of fluoranthene by sulfidated nanoscale zero-valent iron: In aqueous solution and soil slurry
In this study, 90.9% fluoranthene (FLT) was degraded in sodium percarbonate (2Na2CO3·3H2O2, SPC) oxidation system by Fe(II) combined with sulfidated nano zero valent iron (S-nZVI) activation within 60 min in aqueous solution. Scavenging experiments and electron paramagnetic resonance detection suggested that HO•, O2−•, and 1O2 contributed to the removal of FLT in SPC/Fe(II)/S-nZVI system. Based on the FLT degradation intermediates that were analyzed by GC-MS in SPC/Fe(II)/S-nZVI process, three potential FLT degradation pathways were speculated. The removal efficiency of FLT was inhibited with the presence of humic acid (HA) unless the concentration of HA was controlled at 1.0 mg L−1, and the presence of 1.0 mg L−1 HA favored the generation of HO•. The excellent removal performance of FLT (88.6%) could be achieved in actual groundwater by increasing the chemical dosages and adjusting the initial solution pH to acid environment. In soil slurry tests, the optimal reaction time and soil/water ratio were obtained as 24 h and 2/10, respectively, and the desired FLT degradation performances were obtained at pH 3 and 5 with the soil/water ratio of 2/10. This work effectively demonstrates the application potential of SPC/Fe(II)/S-nZVI system for the remediation of PAHs contamination in actual industrial sites.
196. 题目: Efficiency and mechanism of ozonated microbubbles for enhancing the removal of algae and algae-derived organic matter
The effective control of eutrophication caused by algae blooms is still the focus of global attention. The traditional dissolved air floatation process for algae removal has a low adhesion efficiency between bubbles and algal cells and a low removal efficiency of organic pollutants. Aiming to address these defects, this study set up an ozone microbubble-enhanced air flotation experiment to explore the removal trends of algal cells and algal organic matter (AOM) pollution. In contrast to traditional air flotation, this approach targets the removal of various forms of AOM after algal cell damage. The highest removal rates of algal cells, extracellular microcystin (Mc), intracellular Mc-lr and total Mc-lr were 96.6%, 60.1%, 95.2% and 93.7%, respectively. Compared with the traditional process, the absorption rate and utilization rate of ozone were increased by 41.9% and 46.2%, respectively. The removal effect of AOM was also greatly improved, and ozone microbubbles enhanced the removal of aromatic protein-like substances and high-molecular-weight fulvic acid, humic acid and humic substances. The advantageous synergistic effect of ozone and microbubbles on algae removal was analyzed by exploring the enhanced air flotation removal mechanism of ozone microbubbles' enhanced air floatation removal. Good vacuole adhesion and strong oxidation caused by ozone microbubbles jointly guaranteed a good removal rate of AOM. The enhanced air flotation process with ozone microbubbles has high feasibility and a good effect, can effectively remove algal cells and algal pollutants, and has great potential in algal removal and control of water eutrophication.
197. 题目: An investigation into biochar, acid-modified biochar, and wood vinegar on the remediation of saline−alkali soil and the growth of strawberries
The salinization of several hundred million hectares of land poses a serious threat to global food security and biodiversity. Biochar and wood vinegar amendment has been suggested as a possible way to promote plant productivity and improve soil qualities, whereas less emphasis has been placed on the application of biochar in saline−alkaline soils to increase plant productivity. Herein, the single and composite application of sawdust biochar, wood vinegar, and acid-modified biochar on the restoration of coastal saline−alkali soil and plant growth of strawberry seedlings was investigated. Proximate and ultimate analyses and different characterization techniques such as FTIR and scanning electron microscopy were applied to study the physicochemical characteristics of raw and modified biochar. A pot experiment was conducted to explore the effects of different soil additives on soil properties and strawberry growth. Our results revealed that acid-modified biochar shows the most significant promoting effect on strawberry growth, which could increase the weight gain rate, root length, root specific surface area, and root volume of strawberry seedlings by 41.2%, 18.9%, 23.0%, and 34.7%, respectively. Moreover, the application of acid-modified biochar can effectively alleviate soil salinization by reducing soil pH (7.65) and CEC (19.5 cmol/kg). Furthermore, the addition of biochar can significantly improve the community structure of microorganisms (Proteobacteria) and increase the content of bacteria related to soil nutrient cycling (Pseudomonadaceae and Sphingomonadaceae). Preliminary findings from this study suggested that acid-modified biochar is a potentially effective means of preventing soil salinization and increasing economic crop yields.
198. 题目: Effects of co-modified biochar immobilized laccase on remediation and bacterial community of PAHs-contaminated soil
Considering the stability and economy of immobilized enzymes, this study prepared co-modified biochar immobilized laccase product named Fe3O4@NaBC@GA@LC via orthogonal experimental design and explored its possibility of remediating polycyclic aromatic hydrocarbons (PAHs) contaminated soil in steel plants. Compared with the free laccase treatment, the relative activity of Fe3O4@NaBC@GA@LC remained 60% after 50 days of incubation at room temperature. The relative activity of Fe3O4@NaBC@GA@LC could still retain nearly 80% after five reuses. In the process of simulating the PAHs-contaminated site treatment experiment in Hangzhou Iron and steel plant, immobilized laccase exhibited efficient adsorption and degradation performances and even the removal rate of 5-ring PAHs reached more than 90% in 40 days, resulting in improving urease activity and dehydrogenase in the soil and promoted the growth of a PAH degrading bacteria (Massilia). Our results further explained the efficient degradation effects of Fe3O4@NaBC@GA@LC on PAHs, which make it a promising candidate for PAHs-contaminated soil remediation.
199. 题目: Latitudinal patterns of particulate and mineral-associated organic matter down the soil profile in drylands
Understanding the controls on particulate organic matter (POM) and mineral-associated organic matter (MAOM) accumulation is essential in order to accurately predict carbon-climate feedbacks and for ecosystem management. However, how POM and MAOM fractions vary across latitudinal gradients in dryland ecosystems, and what drives this variation remains unclear. In this study, we sampled soils from 100 natural shrubland sites across a latitudinal gradient (23°N to 32°N) in the dry valleys of southwestern China to identify latitudinal patterns of POM and MAOM fractions at four soil depths (0–10 cm, 10–20 cm, 20–30 cm, and 30–50 cm). We found that both C and N fractions in POM and MAOM exhibited a binomial trend with latitude at all depths, whereas the N fractions in POM and MAOM exhibited a pronounced increase at higher latitudes in subsurface soils (20–30 cm and 30–50 cm). Variation in C fractions (i.e., particulate organic carbon (POC) and mineral-associated organic carbon (MAOC)) were mainly explained by the independent effect of soil properties, with the most important explanatory factor being exchangeable calcium. In contrast, variation in N fractions (i.e., particulate organic nitrogen (PON) and mineral-associated organic nitrogen (MAON)) were largely explained by interactions between soil , climate and vegetation properties, with the most important driver being mean annual temperature and mean annual precipitation for PON, exchangeable calcium for MAON at 0–10 cm and 10–20 cm depths, and mean annual temperature for MAON at 20–30 cm and 30–50 cm soil depths. Interestingly, climate was more important in explaining variation in C and N fractions in the subsurface soils, and climate and vegetation properties had higher predictive power for soil N fractions than C fractions in the subsurface soils. These results advance our understanding of the role of soil properties on SOM accumulation in dryland ecosystems. Our study also highlights the important impact of climate and vegetation properties in explaining the spatial variation of SOM in subsurface soils, which should be incorporated into large-scale assessments to better predict SOM dynamics.
200. 题目: Manganese ferrite modified agricultural waste-derived biochars for copper ions adsorption
Biochar is an eco-friendly, low-cost, and carbon-rich material. This study synthesized the biochars from three agricultural wastes, pinecone, white popinac, and sugarcane bagasse, and then modified them by manganese ferrite (MnFe2O4) co-precipitation. These biochars were applied as adsorbents for the removal of Cu(II) ions from water. All three different MnFe2O4-biochars have similar adsorption performances: rapid adsorption kinetics with equilibrium being reached within 5 hr of contact and significantly enhanced adsorption capacities of Cu(II) ions from water. The principal adsorption mechanisms were identified as complexation reactions, contributed by the carboxyl and hydroxyl groups by pristine biochars and by the Mn-O and Fe-O groups for all three MnFe2O4-biochars. The MnFe2O4-biochars can be reused for three cycles, with the maximum adsorption capacities of Cu(II) of the regenerated biochars declining with the loss of precipitated MnFe2O4.