441. 题目: Enhanced removal of tetrabromobisphenol A by Burkholderia cepacian Y17 immobilized on biochar
Biochar-immobilized bacteria have been widely used to remove organic pollutants; however, the enhanced effect of biochar-immobilized bacteria on tetrabromobisphenol A (TBBPA) removal has not been fully investigated and the removal mechanism remains unclear. In this study, a bacterial strain with high TBBPA degradation ability, Burkholderia cepacian Y17, was isolated from an e-waste disassembly area, immobilized with biochar, and used for the removal of TBBPA. Comparisons were performed of the factors affecting the immobilization and TBBPA removal efficiency, including the biochar preparation temperature, immobilization temperature, and pH. The highest 7-day TBBPA removal efficiency by immobilized bacteria was observed with the most suitable biochar preparation temperature (BC500) and an immobilization pH and temperature of 7 and 35 °C, respectively. The TBBPA removal efficiency reached 59.37%, which was increased by 30.23% and 15.88% compared to that of free and inactivated immobilized Y17, respectively. The suitable biochar preparation temperature BC500, immobilization temperature of 35 °C, and neutral pH of 7 increased the bacterial population and extracellular polymer concentration, which facilitated bacterial immobilization on biochar and promoted TBBPA removal. In this case, the high immobilized bacteria concentration (4.62 × 108 cfu∙g−1) and protein and polysaccharide contents (28.43 and 16.16 mg·g−1) contributed to the removal of TBBPA by facilitating TBBPA degradation. The main TBBPA degradation processes by BC500-immobilized Y17 involved debromination, β-scission, demethylation, O-methylation, hydroxylation, and hydroxyl oxidation. This study proposes a method for preparing immobilized bacteria for TBBPA removal and enriches the microbial degradation technology for TBBPA.
442. 题目: Significant contributions of biochar-derived dissolved matters to ecotoxicity to earthworms (Eisenia fetida) in soil with biochar amendment
Biochar (BC) as a soil amendment has been proved to pose potential risks to terrestrial invertebrates. However, the underlying toxic mechanism of BC for soil fauna remains to be elucidated, especially the effects of its different fractions. This work aimed to evaluate the contributions of biochar-derived dissolved matters (BC-DM) and particulate biochar (PBC) to ecotoxicity to earthworms in BC-amended soil, and then uncover the underlying toxic mechanisms. Results showed that the survival rates of earthworms in different treatments decreased by an order of BC (26.5% 0.05) < BC-DM (56.7% 0.03) < PBC (86.7% 0.09), indicating that BC was toxic to earthworms after addition to soil, and BC-DM appeared to be more toxic than PBC. Physiological response of earthworms further confirmed that BC-DM exposure induced more oxidative stress on earthworms than PBC. For example, the glutathione S transferase (GST) activity of earthworms in 4% BC-DM and PBC treatments decreased by 65.1% and 23.3%, respectively. BC and PBC caused slight damage to intestine of earthworms, while no significant change was observed in BC-DM treatments. Transmission electron microscopy (TEM) images revealed that BC, BC-DM and PBC resulted in obvious damage to epidermal tissue. Notably, the epidermis of earthworms suffered severe damage under BC exposure. This study was the first to comprehensively evaluate the ecotoxicity of biochar components to Eisenia fetida, and highlighted the significant contribution of BC-DM to ecotoxicity to earthworms in BC-amended soil. The obtained results could contribute to scientifically assessing the ecological risk of biochar in agricultural soil from multiple perspectives.
443. 题目: Biochar regulates enzymes activity and interspecies electron transfer to promote bioenergy recovery from a continuous two-stage food waste anaerobic digestion process
The influence of biochar on the performance of food waste anaerobic digestion in a continuous two-stage process was examined. Biochar was added to a methanogenic (MG) reactor, with 50% of its effluent recirculated to a hydrolytic–acidogenic (HA) reactor. The addition of biochar in the MG reactor simultaneously enhanced the performance of both reactors, and the energy recovery efficiency increased by 25.01–70.99%. Biochar improved the activities of protease and α-amylase in the HA and MG reactors by 1.08–2.23 and 0.46–1.21, and 13.65–15.76 and 8.73–13.64 times, respectively. The enhancement of these hydrolytic enzymes' activity in the HA reactor was correlated to the effluent recirculation from the MG reactor, contributing to the improved hydrolysis of food waste. Furthermore, the activity of coenzyme F420 in the MG reactor increased by 11.47%, 18.81%, and 27.03%, respectively, indicating that biochar can promote hydrogenotrophic methanogenesis. Microbial analysis revealed that the presence of biochar promoted interspecies hydrogen transfer between Syntrophomonas and hydrogenotrophic methanogens. Additionally, biochar triggered direct interspecies electron transfer between Geobacter sulfurreducens and acetotrophic methanogens, enabling effective methanogenesis.
444. 题目: The role of nonradicals in simultaneous degradation and detoxification of Malachite Green via biochar decorated with δ-MnO 2
The advanced oxidation process (AOPs) has aroused great interest in the fields of sewage treatment for its effective removal performance of varied pollutants which are hard to biodegrade. In this study, -MnO 2 was used to activate PDS, and biochar (BC) was introduced as a capable carrier and electron-transfer provider in PBC@-MnO 2/PDS system. Malachite Green (MG) was selected as a pollutant probe to asses the efficiency of this system, experiments and multiple detection methods were conducted to evaluate the feasibility of MG removal and explore the relevant mechanism of this system. The results showed that wastewater containing MG could still be toxic if it was not thoroughly treated, whereas PBC@-MnO 2/PDS could significantly reduce the toxicity by over 80%, and the major active species in PBC@-MnO 2/PDS system was confirmed to be 1O2 rather than free radicals, which contributed more than the other factors such as physical adsorption, electrostatic interaction and chemical bonding in the process of MG removal. Furthermore, this work comparatively expounded the MG detoxication performance led by 1O2 through T.E.S.T software, and provided novel ideas for the application of PBC@MnO2/PDS system.
445. 题目: Fe12LaO19 fabricated biochar for removal of phosphorus in water and exploration of its adsorption mechanism
Phosphorus (P) runoff from untreated wastewater and agricultural runoff has become an issue of concern because excessive P is detrimental to the health of water bodies and aquatic organisms such as fishes. Hence, different methods are being developed to salvage this challenge. However, most of the methods are expensive, while some are unsustainable. In this study, a simple method was employed in fabricating an absorbent through the co-precipitation of iron and lanthanum on the matrix of biochar prepared from the spent coffee ground for P uptake. The adsorbent named Fe12LaO19@BC was able to attain equilibrium fast within 60 min when used to adsorb P with 98% P removal within the first 30 min Fe12LaO19@BC also maintained high P adsorption across a pH range of 3–7. In the presence of other anions (SO42−, CO32−, NO3−, Cl−, HCO3−) in the solution, Fe12LaO19@BC enabled 71.5–97.8% uptake of P. 81.58 mg P/g maximum adsorption capacity at was reached at 40 °C. The reusability test reveals that about 60% of P uptake was maintained after five adsorption cycles with almost an undisturbed desorption efficiency. The negative value of ΔG°, as shown by the thermodynamic analysis, indicates a favorable and spontaneous reaction during P removal by Fe12LaO19@BC. The XRD analysis showed a major peak corresponding to Fe12LaO19, which is believed to have facilitated the adsorption of P. The adsorption was controlled by multiple mechanisms. An overview of the study indicates Fe12LaO19@BC as a promising adsorbent for the removal of P in the water.
446. 题目: Modeling moisture redistribution from selective non-uniform application of biochar on Palouse hills
Precision agriculture is most effective in areas where significant in-field variation occurs. The Palouse region of the Pacific Northwest in the US, a vast area of undulating fertile farmland, has relatively high in-field variation in water retention and crop yield due to regional topography and uneven soil erosion. The regional agricultural systems depend on the soil at or near field capacity towards the end of a wet spring to support crops throughout the summer drought period. Dryland agricultural systems and high in-field variation and changing climate make water retention management practices throughout the region critical. A finite element vadose zone transport model was developed and used to understand the benefits of the targeted application of biochar on water retention and water redistribution in a representative hillslope. The model utilizes measured soil hydraulic properties to predict soil moisture distribution over the dry season. A Redwood Sawdust and Wheat Straw biochar was amended at 4% and 7% concentrations by mass. Biochar amended soils showed an increase in water retention and apparent reduction in unsaturated hydraulic conductivity as the soil approached saturated conditions. After two months of bare field evaporation, the model showed that biochar impacts water redistribution in the soil profile, contributing to positive and negative changes and a net increase in water retention. Model outputs with biochar showed increased retention in and around the amendment area, although the magnitude between outputs varied, with some samples showing minimal effectiveness. Despite the differences in magnitude with targeted biochar amendment, these results indicate that biochar can change water redistribution (up to 0.5%) in a soil profile. Additionally, the developed model shows promise as a field and regional level management tool to determine the best return on investment from biochar application when applied in a targeted manner.
447. 题目: Natural marsh-pasture/sugarcane field transitions greatly reduced lignin-derived pyrolysis products of soil organic matter
Cultivation of marshes (Ma) to arable like pasture (Pa) and sugarcane (Sa) usually causes soil organic carbon (SOC) pool depletion within a short time. However, there are some uncertainties about which molecular composition of soil organic matter (SOM) is sensitive to land use change (LUC). In the present work, molecular components of SOM were investigated and compared to better understand the impacts of LUC on the carbon cycle from Ma to Pa or Sa in Louisiana and Florida. Pyrolysis-gas chromatography/mass spectrometry (Py-GC/MS) analysis indicated that LUC greatly altered the molecular composition of SOM. More lignin, polysaccharide, and phonetic compounds were founded from Ma, and more nitrogen-containing compounds were identified from Sa. Lignin and phenolic compounds had unexpectedly the most decrease from native marsh-sugarcane/pasture transitions, showing the same trend as SOC. This meant that lignin and phenol were not as stable as expected when undergoing LUC. LUC significantly yield more molecular moieties and then resulted in higher complexities and diversities of molecular components in Pa or Sa than those in Ma. Principal component analysis implied higher contributions of old carbon to SOM in Ma, and fresh biomass input contributed more SOM in Sa. Our results implied that human activities such as LUC could not only alter carbon fluxes but also simultaneously change molecular mechanisms that drive the carbon cycle.
448. 题目: Recognition of variations and its significance of bioavailable organic phosphorus in sediment between high and low risk periods for algal blooms in Lake Erhai
The sediment-bound organic phosphorus (Po) is increasingly recognized as critical internal source for the lake eutrophication process due to its potential bioavailability for organisms. However, limited recognition about the bioavailability variations of sediment Po impeded the in-depth understanding upon the biogeochemical process of Po, especially the differences between high and low risk-periods of algal blooms (HRP-ABs and LRP-ABs). Primarily, significant difference between HRP-ABs (July - December) and LRP-ABs (January - June) was discerned by Mann-Kendall tests of TP, Chla and algal biomass. Biochemical and molecular characterizations, e.g., enzymatic hydrolysis with Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR-MS), were combined to discern the bioavailability variation of sequential extracted sediment Po in HRP-ABs and LRP-ABs. The contents of enzymatically hydrolysable Po decreased in the following order: NaOH-Po > NaHCO3-Po > H2O-Po. The concentrations of bioavailable Po, including labile phosphate monoester (Labile Mono-P) and phosphodiester (Diester-P) were 21.8 - 58.4 mg/kg (averagely 44.3 mg/kg) and 19.5 - 35.8 mg/kg (averagely 28.2 mg/kg) in HRP-ABs and LRP-ABs, respectively. Notably, the amounts of bioavailable H2O-Po and NaHCO3-Po in HRP-ABs (13.4 - 33.3 mg/kg) were nearly 2 - 3 times of that in LRP-ABs (3.9 - 14 mg/kg), while no significant NaOH-Po differences were observed. Similarly, contrasting the HRP-ABs with LRP-ABs, more P-containing formulas were assigned in H2O-Po (2526 vs 1884) and NaHCO3-Po (1554 vs 863), with similar abundance in NaOH-Po. Furthermore, the molecular composition of bioavailable Po (Bio-Po, H/C > 1.2 O/C > 0.5), especially Bio-Po containing two P atoms (Bio-2Po) displayed significant variation in H2O-Po (308 vs 391, 217 vs 316) and NaHCO3-Po (114 vs 208, 40 vs 145) between HRP-ABs and LRP-ABs. This was largely attributed to its their high bioavailability in Bio-2Po (> 50% lipids, proteins and carbohydrates-like). Our findings upon the internal activated accumulation and transformation process interpretation of sediment bioavailable Po are of great significance for lake eutrophication control.
449. 题目: Three-dimensional observations of particulate organic carbon in shallow eutrophic lakes from space
Particulate organic carbon (POC) storage play an essential role in determining carbon sinks and water quality in shallow eutrophic lakes. Although satellite data have been adopted to observe surface POC content, the previous remote sensing results cannot indicate water column-integrated POC storage in shallow eutrophic lakes with vertically nonuniform POC profiles. Based on 272 in-situ POC profiles collected from 19 shallow eutrophic lakes in China's Yangtze-Huai Plain (YHP), this study developed a novel process-oriented method to derive water column-integrated POC storage from OLCI/Sentinel-3A satellite data. The method included three critical steps: remotely estimating surface POC contents, identifying POC profile types (uniform, exponential decay, or power decay) through a binary decision tree, and parameterizing POC profiles using surface POC concentrations. The developed algorithms showed a bias of -25.79% for in-situ match-ups from 15 lakes (N = 88). The POC in the eutrophic lakes was mainly produced by phytoplankton (R2 = 0.87). As a result, the surface POC content presented a unimodal peak in summer. However, in addition to air temperature regulations (0.52 – 68.53%), the water level also showed apparent effects on increasing POC storage, with relative contributions of 29.29 – 95.51% for the six largest lakes. Therefore, multisource satellite data are needed to derive POC storage in global eutrophic lakes remotely. This study is the first attempt to three-dimensionally observe lake POC contents from space and is important for understanding the carbon cycle in shallow eutrophic lakes.
450. 题目: Aboveground organic matter removal reshapes soil microbial functional group balance in temperate forests
The growing demand for renewable materials and energy leads to intensified forest management practices. Therefore, combining high forest productivity and soil carbon storage capacity with lower quantities of organic matter (OM) left on the ground to decompose represents a major challenge. Although microbial communities drive processes responsible for organic carbon stabilization in soil, we have limited knowledge of how the inputs of superficial OM affect the richness and composition of soil microbial communities. This study determined the impacts of OM removal on soil bacteria and fungi at six sites across French temperate forests using high-throughput amplicon sequencing. After three years of OM manipulation, we measured an alteration of the bacterial copiotrophic and fungal saprotrophic abundance and richness. Furthermore, aboveground OM removal reshaped microbial communities toward bacterial oligotrophic and fungal ectomycorrhizal-dominated populations, which are less efficient for OM decomposition. Finally, we proposed that understanding the response of soil microbial communities to variations in OM inputs should help anticipate future functional changes in forest ecosystems submitted to the intensification of silvicultural practices.
451. 题目: Nanovesicle and extracellular polymeric substance synthesis from the remediation of heavy metal ions from soil
Heavy metal toxicity affects aquatic plants and animals, disturbing biodiversity and ecological balance causing bioaccumulation of heavy metals. Industrialization and urbanization are inevitable in modern-day life, and control and detoxification methods need to be accorded to meet the hazardous environment. Microorganisms and plants have been widely used in the bioremediation of heavy metals. Sporosarcina pasteurii, a gram-positive bacterium that is widely known for its calcite precipitation property in bio-cementing applications has been explored in the study for its metal tolerance ability for the first time. S. pasteurii SRMNP1 (KF214757) can tolerate silver stress to form nanoparticles and can remediate multiple heavy metals to promote the growth of various plants. This astounding property of the isolate warranted extensive examinations to comprehend the physiological changes during an external heavy metal stress condition. The present study aimed to understand various physiological responses occurring in S. pasteurii SRMNP1 during the metal tolerance phenomenon using electron microscopy. The isolate was subjected to heavy metal stress, and a transmission electron microscope examination was used to analyze the physiological changes in bacteria to evade the metal stress. S. pasteurii SRMNP1 was tolerant against a wide range of heavy metal ions and can withstand a broad pH range (5–9). Transmission Electron Microscopy (TEM) examination of S. pasteurii SRMNP1 followed by 5 mM nickel sulfate treatment revealed the presence of nanovesicles encapsulating nanosized particles in intra and extracellular spaces. This suggests that the bacteria evade the metal stress by converting the metal ions into nanosized particles and encapsulating them within nanovesicles to efflux them through the vesicle budding mechanism. Moreover, the TEM images revealed an excessive secretion of extracellular polymeric substances by the strain to discharge the metal particles outside the bacterial system. S. pasteurii can be foreseen as an effective bioremediation agent with the potential to produce nanosized particles, nanovesicles, and extracellular polymeric substances. This study provides physiological evidence that, besides calcium precipitation applications, S. pasteurii can further be explored for its multidimensional roles in the fields of drug delivery and environmental engineering.
452. 题目: Soil organic carbon and nitrogen responses to occasional tillage in a continuous no-tillage system
No-tillage (NT) practice is increasingly adopted to improve soil health and sustainability. However, long-term NT may increase soil organic carbon (SOC) and nutrient stratification, soil acidification, compaction, and herbicide resistance in weeds. Targeted strategic disturbance of continuous no-tillage is occasionally practiced to overcome challenges of long-term no-tillage, yet limited information is available on their impacts on SOC and nitrogen (N) components. We evaluated the response of SOC and N fractions to different tillage practices after the imposition of one-time strategic minimum tillage operation (i.e., stubble mulch tillage: SMT) in a continuous NT system in semi-arid drylands. Tillage treatments included conventional tillage (CT), NT, SMT, and strip-tillage (ST). The CT, NT, and ST plots were established in 2013, and SMT plots were established with only one pass of stubble mulch tillage in september of 2019 in long-term NT plots. Soil samples were collected from 0 to 15 and 15–30 cm depth of each plot before SMT and 2-days, 7-months, 14-months, 19-months, and 26-months after SMT implementation. The CT management resulted in 12–27% and 11–16% lower SOC concentration than under NT, SMT, and ST in 0–15 and 15–30 cm depth, respectively. The CT and ST had 22–53%, 44–79%, and 43% greater soil inorganic N than NT and SMT after 2-days, 7-months, and 19-months, respectively, in 0–15 cm depth. The 3d-carbon dioxide-carbon (CO2-C) was 32–65%, 48–65%, 62–102%, and 122–195% greater under CT and ST than under NT and SMT after 2-days, 7-months, 19-months, and 26-months, respectively, in 0–15 cm depth. The microbial biomass carbon (MBC) showed varying responses, with 31–64% lower MBC after 2-days and 26-months, but it was 35–39% greater after 7-months under CT than under NT and SMT. There was no difference between NT and SMT systems on SOC and N fractions for most of the samplings. Further research may reveal how often SMT can be utilized in a long-term NT system without negative impacts on soil properties in semi-arid dryland cropping systems. This study showed one stubble mulch tillage after six years of continuous NT did not affect SOC and N concentrations in 0–30 cm depth.
453. 题目: Adsorption behavior of hierarchical porous biochar from shrimp shell for tris(2-chloroethyl) phosphate (TCEP): Sorption experiments and DFT calculations
Tris(2-chloroethyl) phosphate (TCEP) as a new type of flame retardant exists in various water environments, causing great risks to humans and the environment. In this study, shrimp shell was used to prepare an economical and environmental-friendly adsorbent for the efficient removal of TCEP. The systematic studies including characterization, removal performance, and adsorption mechanism of shrimp shell biochar toward TCEP were carried out. Adsorption kinetics and thermodynamics showed that fast equilibrium reached within 30 min, the maximum adsorption capacity qm was 108 μmol g−1 at 298 K, and the adsorption process is spontaneous and exothermic. The environmental factor, such as temperature, pH, inorganic anions and organic matter hardly affected the adsorption performance. Structural characterization indicated that the hierarchical porous structure of shrimp shell biochar is the key to excellent adsorption performance. The adsorption mechanisms were further revealed using density functional theory (DFT) calculations, and the hydrogen bond, van der Waals interactions, Cl–H interactions, and pi-H interactions were identified as potential interaction mechanisms between TCEP and specific biochar structures. The calculated binding energy between TCEP and simplified biochar structure suggested that oxygen-containing groups especially carboxyl, hydroxyl and aldehyde facilitate the adsorption. Our work not only provides a novel strategy for the quick remediation of organophosphate-contaminated water environments but also offers new opportunities for crustacean waste biomass valorization.
454. 题目: Unraveling gas charging and leakage for oil reservoirs in the Mahu sag of the Junggar Basin, NW China using concentrations and ratios of biomarkers, light hydrocarbons and diamondoids
It remains disputed why a large amount of oil but only a limited amount of gas has been discovered in the northwestern Junggar Basin of China, although most source rocks are post-mature. Quantitative GC, GC–MS and GC–IRMS analyses were performed on 92 oils from this region to investigate gas charging and leakage of the petroleum reservoirs in the Mahu sag and nearby areas of the northwestern portion of the Junggar Basin. The 92 oils have moderate to high concentrations of C30 hopane (18–3840 ppm) and ΣC29 regular steranes (38–6100 ppm), demonstrating that these oils have normal maturities, within the oil generation window. However, these oils have high heptane and isoheptane values in the ranges of 31.1–52.2 and 0.82–7.74, respectively, and diamondoid (4- + 3-methyldiamantanes) concentrations over a wide range of 1.07–22.0 ppm. These results demonstrate that the reservoirs for all the studied oils have multiple charging episodes: terpanes and steranes entered the reservoirs along with the initial oil charges from source rocks within the oil generation window while light hydrocarbons and diamondoids mainly entered the reservoirs along with the late gas and condensate charging from deep post-mature source rocks. The difference between the maximum and minimum 4- + 3-methyldiamantane (4+3MD) concentrations (Cmax – Cmin)/Cmax is equal to 0.95. A higher ratio of (Cmax – Cmin)/Cmax (> 0.50) can be indicative of late gas and condensate charging to the reservoirs. Lower gas/oil ratios (GOR) for the reservoirs of the studied oils can be mainly ascribed to gas leakage.
455. 题目: Effectiveness of mixing poultry litter compost with rice husk biochar in mitigating ammonia volatilization and carbon dioxide emission
Nitrogen-rich materials such as poultry litter (PL) contributes to substantial N and C loss in the form of ammonia (NH3) and carbon dioxide (CO2) during composting. Biochar can act as a sorbent of ammonia (NH3) and CO2 emission released during co-composting. Thus, co-composting poultry litter with rice husk biochar as a bulking agent is a good technique to mitigate NH3 volatilization and CO2 emission. A study was conducted to evaluate the effects of composting the mixtures of poultry litter with rice husk biochar at different ratios on NH3 and CO2 emissions. Four mixtures of poultry litter and rice husk biochar at different rate were composted at 0:1, 0.5:1, 1.3:1 and 2.3:1 ratio of rice husk biochar (RHB): poultry litter (PL) on a dry weight basis to achieve a suitable C/N ratio of 15, 20, 25, and 30, respectively. The results show that composting poultry litter with rice husk biochar can accelerate the breakdown of organic matter, thereby shortening the thermophilic phase compared to composting using poultry litter alone. There was a significant reduction in the cumulative NH3 emissions, which accounted for 78.38%, 94.60%, and 97.30%, for each C/N ratio of 20, 25, and 30. The total nitrogen (TN) retained relative was 75.96%, 85.61%, 90.24%, and 87.89% for each C/N ratio of 15, 20, 25, and 30 at the completion of composting. Total carbon dioxide lost was 5.64%, 6.62%, 8.91%, and 14.54%, for each C/N ratio of 15, 20, 21, and 30. In addition, the total carbon (TC) retained were 66.60%, 72.56%, 77.39%, and 85.29% for 15, 20, 25, and 30 C/N ratios and shows significant difference as compared with the initial reading of TC of the compost mixtures. In conclusion, mixing and composting rice husk biochar in poultry litter with C/N ratio of 25 helps in reducing the NH3 volatilization and CO2 emissions, while reducing the overall operational costs of waste disposal by shortening the composting time alongside nitrogen conservation and carbon sequestration. In formulating the compost mixture with rice husk biochar, the contribution of C and N from the biochar can be neglected in the determination of C/N ratio to predict the rate of mineralization in the compost because biochar has characteristic of being quite inert and recalcitrant in nature.
456. 题目: Linking bacterial life strategies with soil organic matter accrual by karst vegetation restoration
Vegetation restoration affects belowground microbial diversity and trait-based life strategies, as well as soil organic matter (SOM) accumulation. Despite the growing focus on microbial diversity, the relationship between life strategies and SOM accrual following vegetation restoration remains unclear. We used three independent but complementary approaches to relate six soil parameters to SOM accrual and further connected them with microbial diversity and life strategies. Sites with two vegetation restoration strategies (after 15 years of vegetation recovery): i) actively planted forests and ii) passive naturally regenerating forests, were compared with croplands and established 60-year-old secondary forests. Data from seven sites along a large climatic gradient (Δ temperature >9 °C) in subtropical karst regions showed that the average index of SOM accrual increased by 47% in plantations and by 60% in natural regeneration forests compared to that in croplands, but remained lower than that of secondary forests. Related soil parameters (water holding capacity, organic carbon and total nitrogen contents, and bacterial and fungal biomasses) were comparable. Compared to croplands, vegetation restoration decreased the sensitivity of the soil parameters to climate warming. Vegetation restoration reduced bacterial diversity and shifted the community towards K-strategy, as evidenced by i) lower 16S rRNA operon copy number and ii) higher ratios of phyla classified a priori as oligotrophic versus copiotrophic bacteria. These changes were mainly attributed to the decline in labile nutrient content and increase in carbon stability in calcium-rich karst soils after vegetation restoration. Bacterial diversity was negatively associated with SOM accrual at low levels of functioning, whereas the prevalence of K-strategists showed a strong positive association with it, especially at near-peak capacity. Consequently, i) bacterial rather than fungal diversity and life strategies are associated with SOM accrual, and ii) linking bacterial life strategies with SOM accrual is important to deepen the understanding of soil-microbial interactions.
457. 题目: Transformation of dissolved organic matter at a full-scale petrochemical wastewater treatment plant
Transformation of dissolved organic matter (DOM) in petrochemical wastewater (PCW) treatment has rarely been studied. In this work, low- and high-salinity PCW were collected from a treatment plant and the transformations of DOM at molecular level along the treatment processes of both PCW were comparatively investigated. By using Orbitrap MS, the polar DOM constituents were categorized into five molecular classes namely saturated compounds, aliphatics, highly unsaturated and phenolic compounds (Huph), polyphenols and condensed polycyclic aromatics (Cpla). Aliphatics (58.62%) with low molecular weight (150–250 Da) and O/C (0–0.2) were dominant in raw low-salinity PCW; while Huph (65.03%) with O/C at 0.2–0.8 were rich in raw high-salinity PCW. After full-scale treatment, differentiated DOM constituents in both raw PCWs were transformed into aliphatics and Huph with O/C at 0.3–0.5. Anoxic/Oxic treatment of low-salinity system (L-A/O) removed a high fraction of aliphatics (53.05%); while Huph with low O/C (0.1–0.3) (65.68%) in the effluent of L-A/O were further mineralized by ozonation of low-salinity system (L-ozonation). In comparison, anoxic/oxic treatment of high-salinity system (H-A/O) mainly removed unsaturated Huph (34.10%) and aliphatics (30.86%). This resulted in a decrease of dissolved organic carbon as indicated via Spearman correlation. Different from L-ozonation, ozonation of high-salinity system (H-ozonation) degraded aliphatics (26.09%) and Huph (41.85%) with a relatively high O/C (0.2–1.2). After L-A/O and L-ozonation treatments, remaining saturated compounds that were originated from raw low-salinity PCW, were removed by subsequent biological aerated filter. Comparatively, after H-A/O and H-ozonation treatments, residual Huph and aliphatics which were mainly bio-derivates and ozonated intermediates, were further removed by air flotation filter. Hence, DOM transformation of different PCWs along similar treatments varied significantly. This study provides in-depth insights on DOM transformation along a full-scale PCW treatment process.
458. 题目: Mangrove sediment erosion in the Sunda Shelf during meltwater pulses: Insights from biomarker records
Mangroves have received increasing attention in recent years for their high carbon storage capacity. The effects of sea-level change during the last glacial period on terrestrial deposition and coastal mangrove ecosystems were investigated using various organic lipid proxies in marine sediment cores from the Sunda Shelf in the southern South China Sea (SCS). The gradual reduction in the content of long-chain n-alkanes and n-alkanols, BIT index, and increasing δ13Corg trend from the last glacial to the Holocene indicated that the depocenter moved landward from the studied location during the deglacial sea-level rise. Remarkable peaks in the mangrove proxy (Taraxerol/n-C28 alcohol ratio) occurred during meltwater pulse (MWP) events in the Sunda shelf area, associated with the drowning and destruction of mangroves that could not withstand the rapid sea-level rise. The decomposition of carbon-rich mangrove deposits may have contributed to atmospheric CO2 concentration during two strong MWP events in Sunda Shelf. Our results suggest the vulnerability of mangrove systems upon rapid sea level change with positive feedback for global warming.
459. 题目: Variations in organic carbon mineralization of the biological soil crusts following revegetation in the Tengger Desert, North China
Revegetation is an effective measure to combat desertification worldwide, which parallelly facilitates the colonization and development of biological soil crusts (BSCs), and thereby affecting C cycles of BSCs in desert regions. However, knowledge about soil organic carbon (SOC) mineralization of BSCs and the involved mechanisms during long-term revegetation process in desert is rather limited. In this study, SOC mineralization rates of the mobile sand dune (MSD) and the BSCs in revegetated sites along chronosequence in the Tengger Desert were investigated, and the relationships between the SOC mineralization and the characteristics of vegetation and BSCs, soil properties and incubation temperature (T) and soil water content (SWC) were analyzed. The results showed that SOC mineralization rate of the BSCs and the corresponding subsoils was significantly greater than those of the MSD, and it increased considerably with increasing site age, regardless of the T, SWC, soil layer and sampling time (p < 0.001). The maximum instantaneous mineralization rates (MIR), cumulative CO2-C release (CCR) and the potentially mineralizable SOC (C0) of BSCs and subsoils were 1.29–12.63, 3.67–23.16 and 3.78–23.41 times, and 0.16–2.26, 0.12–1.84 and 0.17–1.26 times greater than those of the MSD, respectively; while the proportion of C0 to total SOC (C0/SOC) decreased by 31–88 % and 24–72 % in comparison with MSD, respectively. The mineralization rate increased with T and SWC, and the temperature sensitivity of BSCs increased with site age, indicating that the loss of SOC would be accelerated with the succession of BSCs upon the future global change. The variation magnitude of SOC mineralization was largely dependent on revegetation-induced changes in the properties of BSCs and the incubation T and SWC, and their interactions. The C:N, pH, and the activities of POD and PPO and DOC, and the coverage of moss-dominated crusts, SOC, C:N, the content of clay and silt and AYL activity were the main factors affecting SOC mineralization of BSCs and the subsoils, respectively. These results indicated that multiple factors that co-varied with the succession of BSCs led to variable SOC mineralization. Our findings suggested that planting xerophytic shrubs in desert drives the development and the SOC mineralization of BSCs, but decreased SOC loss due to mineralization, leading to SOC sequestration.
460. 题目: Immobilization effect of heavy metals in biochar via the copyrolysis of sewage sludge and apple branches
The excess sludge produced by sewage treatment plants can be recycled into energy through pyrolysis, and the byproduct biochar can be used for soil remediation. However, the heavy metals in sludge are retained in biochar after pyrolysis and may cause secondary pollution during its soil application. Herein, a fast copyrolysis method of activated sludge (AS) and apple branches (AT) was proposed to immobilize heavy metals while improving bio-oil yield. The results showed that the heavy metal release from the copyrolyzed biochar was markedly reduced compared with that from the biochar produced through the pyrolysis of AS alone (78% for Cr and 28% for Pb). The kinetic behavior of ion release from different biochars could be described by a first-order kinetic model. The excellent fixation of heavy metals was attributed to complexation by abundant oxygen-containing surface functional groups (–O–, =O, and –CHO) that were mainly donated by AT. Furthermore, high-temperature pyrolysis was conducive to the fixation of metals, and the release of Pb2+ and Cr3+ from the biochar pyrolyzed at 600 °C was approximately 2/3 and 1/10 of that from the biochar pyrolyzed at 400 °C, respectively. A growth experiment on Staphylococcus aureus and Escherichia coli revealed that the toxicity of the copyrolyzed biochar was greatly reduced. This work can provide a method for heavy metal fixation and simultaneous resource recovery from organic wastes.