41. 题目: Remediation of Lead-Contaminated Water by Virgin Coniferous Wood Biochar Adsorbent: Batch and Column Application
42. 题目: Evaluating the protection of bacteria from extreme Cd (II) stress by P-enriched biochar
Cadmium cations (Cd2+) are extremely toxic to organisms, which limits the remediation of Cd by microorganisms. This study investigated the feasibility of applying biochar to protect bacteria from extreme Cd2+ stress (1000 mg/L). An alkaline biochar (RB) and a slightly acidic biochar (SB) were selected. SB revealed a higher Cd2+ removal than RB (15.5% vs. 4.8%) due to its high surface area. Addition of Enterobacter sp. induced formation of Cd phosphate and carbonate on both SB and RB surface. However, Cd2+ removal by RB enhanced more evidently than SB (78.9% vs. 30.2%) due to the substantial microbial regulation and surficial alkalinity. Thermogravimetric analysis (TGA), X-ray photoelectron spectroscopy (XPS) and geochemical modeling (GWB) all confirmed that the formation of stable Cd phosphate on RB was superior to that in SB. These biomineralization, together with biochar pore structure, protect bacterial cells from Cd stress. Moreover, the alkalinity of biochar promoted the formation of carbonate, which strengthened the decline of Cd2+ toxicity. The protection by RB was further confirmed by the intense microbial respiration and biomass (PLFA). Furthermore, this protection induced a positive feedback between P-abundant biochar and Enterobacter sp.: biochar provides P source (the most common limiting nutrient) to support microbial growth; bacteria secrete more organic acids to drive P release. This study therefore elucidated the protection of bacteria by P-enriched biochar based on both physic-chemical and microbial insights.
43. 题目: The large proportion of black carbon (BC)-containing aerosols in the urban atmosphere
The accurate derivation of the proportion and absorption enhancement of black carbon (BC)-containing aerosols in the atmosphere is critical to assess their effect on air quality and climate. Here, using the field measured size-resolved volatility shrink factor, BC bulk mass concentration and the BC mass fraction in BC-containing particles in winter Beijing, we retrieved and quantified both the number and mass concentration of (1) non-BC, (2) internally mixed BC and (3) externally mixed BC of ambient fine aerosol particles. The reliability of the retrieval method has been evaluated by comparing with the simultaneously measured data. The number fraction of BC-containing particles accounts for 60–78% of ambient fine particles, with internally (both BC core and coating materials) and externally mixed BC of 51–64% and 9–23%, respectively. Only for nucleated particles on clean days, when nucleation is a major source of aerosol particles, did the non-BC component dominate (54%). A large amount of aerosols are BC-containing particles, with mass fraction of 32–52%, suggesting the dominant role of BC in elevating mass concentration of particulate matter (PM) in a polluted urban area. We also show that the BC particles are thickly coated with coating thickness (characterized by Dp/Dc, ratio of the BC diameter before and after heating at 300 °C) of 1.6–2.2, implying efficient aging of BC particles in polluted urban area. Our results imply a large proportion of BC-containing particles in the atmosphere, which could help towards understanding the role of BC on regional haze formation and climate forcing.
44. 题目: The role of soil carbon in natural climate solutions
45. 题目: Mercury distributions in sediments of an estuary subject to anthropogenic hydrodynamic alterations (Patos Estuary, Southern Brazil)
46. 题目: Prevalent root-derived phenolics drive shifts in microbial community composition and prime decomposition in forest soil
Phenolic compounds perform various functions in soil ranging from substrate to toxin and form the basis of several plant-mediated processes. The aim of this study was to investigate how phenolics commonly exuded by tree roots influence soil organic matter (SOM) decomposition and interact with other labile forms of carbon (C) abundant in root exudates. We performed a 38-day incubation experiment to determine whether phenolic compounds (benzoic acid, caffeic acid and catechin) facilitate or inhibit SOM decomposition in a glucose-amended forest soil. Changes in decomposition, substrate use, fungal and bacterial community composition, and microbial abundance and activity were assessed over time using 13C-stable-isotope tracing, DNA-based molecular methods and enzyme assays. Our findings showed that phenolics inhibited microbial activity and abundance to varying degrees. Yet, benzoic acid was the only compound producing a substantial priming effect leading to a 21% increase in SOM decomposition, which was amplified in glucose-amended soils. This stimulation in microbial activity was associated with an increase in β-1,4-glucosidase activity and the bacterial genera Paraburkholderia and Caballeronia genera of the Burkholderiaceae family. Phenolics drove microbial community shifts in glucose-amended soils with negligible interactive effects. In conclusion, phenolic priming of SOM decomposition is associated with microbial community shifts and amplified in the presence of glucose. This evidence emphasizes the need for considering phenolics and interactions among root exudates as priming mechanisms in the rhizosphere and other soil environments where aromatics and phenolic acids are abundant.
47. 题目: Tidal elevation is the key factor modulating burial rates and composition of organic matter in a coastal wetland with multiple habitats
This study examines long-term burial rates of organic carbon (OC), organic nitrogen (ON), and total sulphur (TS) in a tidal-dominated coastal wetland with a high spatial heterogeneity and habitat diversity, and long history of human impacts, Cádiz Bay (SW Spain). Using replicate sediment cores, we quantified fluxes of these elements over a transect, extending from the lower saltmarsh (Spartina maritima, ~0.3 m mean sea level, MSL) to the lower intertidal region (Zostera noltei, ~ − 0.7 m MSL). Potential organic matter (OM) sources to the sediment were examined using an extensive dataset on carbon and nitrogen stable isotopes, and C:N molar ratios of primary producers in the region. OC burial rates decreased from the sites below MSL (~80 gC·m−2·y−1) to the lower saltmarsh (~50 gC·m−2·y−1), whereas ON burial rates showed an opposite pattern (~3 gN·m−2·y−1 and ~4 gN·m−2·y−1 observed below and above MSL, respectively). TS burial rates (0.5–46 gS·m−2·y−1) did not show any trend along the sea-land gradient. Hence, (tidal) elevation appeared to be an important determinant of sediment biogeochemical properties, and predictor of OM burial rates. The Bayesian mixing model suggested a well-mixed combination of subtidal and terrestrial/high-marsh OM sources to the surface sediments, with no clear indication of an increased contribution from the particular vegetation species inhabiting the sediments. The indication that there is substantial transport, remineralization and cycling of OM between habitats, suggests diversity may play an important role in maintaining this function, reinforcing the idea that a holistic, catchment-scale view is appropriate for understanding and preserving the long-term burial of OM in coastal wetlands.
48. 题目: Nitrous oxide emissions from oilseed rape cultivation were unaffected by flash pyrolysis biochar of different type, rate and field ageing
Nitrous oxide (N2O) emission from winter oilseed rape (WOSR) cultivation may compromise the sustainability of oilseed rape biodiesel. Typically, greenhouse gas budgets of WOSR cultivation assume an N2O emission factor (EF) of 1% of the N added in fertilizer and crop residues. Management options to reduce direct soil emissions of N2O include the application of biochar, but efficacy and mechanisms of N2O suppression are elusive. We measured N2O emissions in a WOSR field trial on a sandy loam soil in Denmark over 402 days in 2017–2018, comparing biochar applications from two feedstocks (wheat straw and pig manure fibers), two application rates (1.5 and 15 Mg ha−1) and field ageing of up to three years. Further, a controlled incubation experiment was performed to examine the effect of biochar dose and ageing on N2O production and consumption by denitrification. Biochar treatments had no significant effects on cumulative N2O emissions (1.71–2.78 kg N ha−1 yr−1). Likewise, no significant effects were found on crop yield, yield-scaled N2O emission, soil mineral N content, gravimetric soil moisture or pH. The fertilizer induced EF was 0.51% which is well below the IPCC Tier 1 EF of 1%. High doses of fresh, but not field-aged biochar suppressed N2O production under anoxic conditions ex situ, suggesting that biochar with sufficient liming capacity could mitigate N2O emissions from denitrification also under field conditions. Yet, rates of up to 15 Mg ha−1 flash pyrolysis biochar in the current in situ study, which comprised a pronounced summer drought, showed no significant N2O mitigation. This highlights the need for selecting dedicated biochars and doses and test them in multi-year studies to conclude on their N2O mitigating effect. Yet, in relation to sustainability of WOSR cultivation for biodiesel, the current study suggests that C sequestration by biochar is not compromised by increased N2O emissions.
49. 题目: Contrasting mixing state of black carbon-containing particles in summer and winter in Beijing
Black carbon (BC) exerts a large impact on climate radiative forcing and public health, and such impacts depend strongly on chemical composition and mixing state. Here a single particle aerosol mass spectrometry (SPA-MS) along with an aerosol chemical speciation monitor was employed to characterize the composition and mixing state of BC-containing particles in summer and winter in Beijing. Approximately 2 million BC-containing particles were chemically analyzed, and the particles were classified into nine and eight different types in summer and winter, respectively, according to mass spectral signatures and composition. The BC-containing particles in summer were dominated by the type of nitrate-related BC (BC-N, 56.7%), while in winter the BC mixed with organic carbon (OC) and sulfate (BCOC-S), and OC and nitrate (BCOC-N) were two dominant types accounting for 44.9% and 16.6%, respectively. The number fractions of BC-N in summer, and BCOC-N and BC-SN in winter increased largely during periods with severe air pollution, suggesting the enhanced secondary formation on BC-containing particles. We also found that the primary emissions of the biomass burning and coal combustion can affect BC mixing state substaintially as indicated by the considerable fraction of BC mixed with levoglucosan and polycyclic aromatic hydrocarbons in winter. Bivariate polar plots and back trajectory analysis indicated that the sulfate-associated BC-containing particles were mostly from regional transport while the nitrate-related type was more from local production. The optical parameter of absorbing Ångström exponents (AAE) of BC was 1.2 and 1.5 in summer and winter, respectively, and the AAE dependence of BC mixing state was also different in the two seasons. While higher fractions of BC-N were observed during lower AAE periods in summer, the variations of dominant OC-related BC-containing particles in winter were fairly stable as a function of AAE.
50. 题目: Rice straw biochar mitigated more N2O emissions from fertilized paddy soil with higher water content than that derived from ex situ biowaste
Biochar could mitigate greenhouse gas emissions, especially nitrous oxide (N2O). Effects of interactions between different biochar and water content on N2O emissions from rice (Oryza sativa L.) paddy soils have not been thoroughly understood. We evaluated effects of different biochar (derived from Camellia oleifera fruit shell, FS; spent mushroom substrate made of Camellia oleifera fruit shell, MS; rice straw, RS; at the rate of 40 g kg−1) and water contents (70% and 120% water holding capacity, WHC) on N2O emissions from rice paddy soil fertilized with nitrogen (N, 0.2 g kg−1), and examined microbial functional genes associated with N2O emissions to understand the underlining mechanisms. The results showed that RS biochar was higher in pH, available N, dissolved organic N, and decreased more N2O emissions from soils with N and 120% WHC treatment relative to MS and FS biochar (by 363% and 200%, respectively). Although RS biochar potentially increased the abundance of ammonia-oxidizing archaea amoA gene (AOA), changes in functional gene abundance did not concur with decreases in N2O emissions. Instead of changes in microbial communities, the relatively higher pH as well as lower available N and dissolved organic C and N of RS biochar could have contributed to the decrease in N2O emissions compared with MS and FS biochar. Thereby, the in situ application of rice straw via biochar could be considered in the mitigation of N2O emissions from fertilized rice paddy soil instead of biochar derived from ex situ feedstock.
51. 题目: Bacterial response mechanism during biofilm growth on different metal material substrates: EPS characteristics, oxidative stress and molecular regulatory network analysis
Overwhelming growth of bacterial biofilms on different metal-based pipeline materials are intractable and pose a serious threat to public health when tap water flows though these pipelines. Indeed, the underlying mechanism of biofilm growth on the surface of different pipeline materials deserves detailed exploration to provide subsequent implementation strategies for biofilm control. Thus, in this study, how bacteria response to their encounters was explored, when they inhabit different metal-based pipeline substrates. Results revealed that bacteria proliferated when they grew on stainless steel (SS) and titanium sheet (Ti), quickly developing into bacterial biofilms. In contrast, the abundance of bacteria on copper (Cu) and nickel foam (Ni) substates decreased sharply by 4–5 logs within 24 h. The morphological shrinkage and shortening of bacterial cells, as well as a sudden 64-fold increase of carbohydrate content in extracellular polymeric substances (EPS), were observed on Cu substrate. Furthermore, generation of reactive oxygen species and fluctuation of enzymatic activity demonstrated the destruction of redox equilibrium in bacteria. Bacteria cultured on Cu substrate showed the strongest response, followed by Ni, SS and Ti. The oxidative stress increased quickly during the growth of bacterial biofilm, and almost all tested metal transporter-related genes were upregulated by 2–11 folds on Cu, which were higher than on other substrates (1–2 folds for SS and Ti, 2–9 folds for Ni). Finally, these behaviors were compared under the biofilm regulatory molecular network. This work may facilitate better understanding different response mechanisms during bacterial biofilm colonization on metal-based pipelines and provide implications for subsequent biofilm control.
52. 题目: Analyzing the inhibitory effect of metabolic uncoupler on bacterial initial attachment and biofilm development and the underlying mechanism
Metabolic uncouplers inhibit biofilm and biofouling formation in membrane bioreactor (MBR) systems, which have been considered as a potential biofouling control alternative. To better understand the inhibitory mechanism of uncoupler on biofouling, this study investigated the impact of the uncoupler 3, 3′, 4′, 5-tetrachlorosalicylanilide (TCS) on biofilm formation of B. subtilis in different development stages. Significant reductions in both the initial bacterial attachment stage and the subsequent biofilm development stage were caused by TCS at 100 μg/L. The motility of B. subtilis in semisolid medium was inhibited by TCS, which explicitly explained the reduction in initial bacterial attachment. Meanwhile, a reduction of extracellular polymeric substance (EPS) secretion owing to TCS suggested why biofilm development was suppressed. In addition, the fluorescent materials in tight-bound EPS (TB-EPS) and loose-bound EPS (LB-EPS) of Bacillus subtilis cultured in different TCS concentrations were distinguished and quantified by three-dimensional excitation-emission matrix (EEM) fluorescence spectroscopy coupled with parallel factor analysis (PARAFAC). The results of this study suggested that the biofilm inhibitory mechanism of the uncoupler was both a inhibition in bacterial motor ability and a reduction in EPS secretion.
53. 题目: The asynchronous disappearance of conodonts: New constraints from Triassic − Jurassic boundary sections in the Tethys and Panthalassa
The End-Triassic Extinction event (ETE) has been recognized in numerous sections worldwide and it is usually marked by three negative carbon isotope excursions (NCIEs), named precursor (P-NCIE), initial (I-NCIE) and main (M-NCIE) negative carbon isotope excursions. These three NCIEs are significant characteristics of this time interval, and they are likely related to the emplacement of the Central Atlantic Magmatic Province (CAMP) that is considered the main trigger of the ETE. Stable carbon isotope excursions, commonly related to biotic turnovers and extinctions, play an important role in stratigraphic correlations, particularly around the Triassic/Jurassic boundary (TJB). This time interval records the disappearance of conodonts, elements of a feeding apparatus belonging to marine organisms that populated the Paleozoic-early Mesozoic seas, and which became extinct across the TJB. So far, the interpretation of conodont extinction has remained ambiguous, as the timing of its last occurrence was debated which in turn hindered our understanding of the main cause(s) that could have led to their disappearance. Here we present and compare integrated data of nine TJB sections from different areas, Tethys and Panthalassa, and different depositional environments, i.e. shallow vs deep water or proximal vs distal shelf. Each of these sections record both the last occurrences of latest Triassic conodont taxa and pronounced changes in the carbon isotopic composition of organic matter across the TJB interval. Our analysis of chemo- and integrated biostratigraphic correlation suggests that the final extinction of the taxon Conodonta was asynchronous.
54. 题目: Global patterns of soil heterotrophic respiration – A meta-analysis of available dataset
Soil heterotrophic respiration (RH) represents the carbon losses from the decomposition of litter detritus and soil organic matter by microorganisms. Despite conflicting findings on the dominant climatic, soil and vegetation controls on RH from local studies, little is known on the global patterns of RH and the potential drivers behind these patterns. Based on the updated Global Soil Respiration Database, we conducted a meta-analysis to evaluate the direct and indirect effects of climatic, soil and vegetation controls on RH across the globe using structure equation model (SEM). Our results showed that the global weighted mean RH was 457 ± 139 g C m−2 a−1 (mean ± standard deviation), but RH differed significantly among ecosystem types and positively correlated with gross primary production, highlighting the importance of the vegetation control on RH. Climate was the most important environmental control on RH indicated by SEM. Soil organic carbon (SOC) content had a negative influence on RH at the global scale, challenging the current understanding that SOC leads to a positive effect on RH at site or ecosystem scale, further indicating that SOC quantity may dominate RH at local scales, while SOC quality and availability may dominate RH at regional or global scales. Great differences were found not only between observed and dymanic global vegetation model (DGVM)-based RH, but also among different DGVMs, highlighting a better parameterizing of DGVMs, particularly the model output not validated by field observations, to better understand RH and belowground carbon dynamics.
55. 题目: Precoating membranes with submicron super-fine powdered activated carbon after coagulation prevents transmembrane pressure rise: Straining and high adsorption capacity effects
Commercially available powdered activated carbon (PAC) with a median diameter of 12–42 μm was ground into 1 μm sized superfine PAC (SPAC) and 200 nm sized submicron SPAC (SSPAC) and investigated as a pretreatment material for the prevention of hydraulically irreversible membrane fouling during a submerged microfiltration (MF) process. Compared with PAC and SPAC, SSPAC has a high capacity for selective biopolymer adsorption, which is a characteristic found in natural organic matter and is commonly considered to be a major contributor to membrane fouling. Precoating the membrane surface with SSPAC during batch filtration further removes the biopolymers by straining them out. In lab-scale membrane filtration experiments, an increase in the transmembrane pressure (TMP) was almost completely prevented through a precoating with SSPAC based on its pulse dose after coagulation pretreatment. The precoated SSPAC formed a dense layer on the membrane preventing biopolymers from attaching to the membrane. Coagulation pretreatment enabled the precoated activated carbon to be rinsed off during hydraulic backwashing. The functionality of the membrane was thereby retained for a long-term operation. Precoating the membranes with SSPAC after coagulation is a promising way to control membrane fouling, and efficiently prevents an increase in the TMP because of the straining effect of the SSPAC and the high capacity of the SSPAC to adsorb any existing biopolymers.
56. 题目: Microstructure and composition of marine aggregates as co-determinants for vertical particulate organic carbon transfer in the global ocean
57. 题目: Phosphorus transformation under the influence of aluminum, organic carbon, and dissolved oxygen at the water-sediment interface: A simulative study
58. 题目: Nitrogen, water content, phosphorus and active iron jointly regulate soil organic carbon in tropical acid red soil forest
Increasing forest soil organic carbon (SOC) storage is important for reducing carbon dioxide (CO2) emissions from terrestrial ecosystems and mitigating global climate change. Although the effects of altitude, temperature, and rainfall on organic carbon have been studied extensively, it is difficult to increase SOC storage by changing these factors in actual forest management. This study determined the SOC, soil physical and chemical properties, nutrient elements, heavy metal elements, soil minerals, and microbial biomass in the 0–140 cm soil layer of the monsoon broad‐leaved forest in the acid red soil region of southwestern China by stratification. We tried to identify the soil factors affecting the SOC storage of the forest in the acid red soil region and determine the weights of the factors affecting the SOC with the aim of improving the SOC retention capacity in forest management by changing the main soil factors affecting SOC storage. The results showed that the soil factors affecting the forest SOC storage in this area are total nitrogen (N, 22.7%) > soil water content (19.9%) > active iron (including poorly crystalline iron, Feo, 15.5%) > pH (9.5%) > phosphorus (P, 9.4%) > aluminium (Al, 8.9%) > silicon (Si, 7.1%) > sulphur (S, 6.8%). Of these factors, N, the water content, Feo, and P are practical factors for forest management, whereas the pH, Al, Si, and S are not. SOC was significantly positively correlated with the soil N concentration, water content, active iron content, and P concentration (p < 0.05). In acidic red soil areas, with active iron as the highlight, N, soil water content, phosphorus and active iron jointly regulate the forest SOC storage capacity. Consequently, in actual forest management, any measures to promote soil N, water content and to activate inactive iron can enhance the storage of SOC, as appropriate input of N and P fertiliser and irrigation in dry years and the dry season.
59. 题目: Enhancement of auxiliary agent for washing efficiency of diesel contaminated soil with surfactants.
We used five types of surfactants assisted with sodium salts, including sodium tartrate (ST), sodium chloride (SC), and humic acid sodium (HAS) as auxiliary agents for soil washing to remove diesel from contaminated soil. Decontamination enhancement of diesel polluted soil washing with biosurfactant and H2O2 was examined, which showed higher effectiveness for newly contaminated soil. An increase in temperature and sodium salt addition exhibited a profound enhancement in diesel removal from aged contaminated soils. Compared to ST and SC, HAS exhibited a higher removal efficiency with saponin washing for aged diesel contaminated soil by lowering surface tension, shifting zeta potential, and increasing the number of micelles. Phytotoxicity experiments showed no significant inhibition of germination of lettuce, arugula, and cucumber with 0.2 g L−1 saponin incubation. Conversely, there was a promotion on the root extension of lettuce and cucumber except for arugula. Similarly, the addition of 2% HAS (wight of saponin) improved on root growth of lettuce, arugula, and cucumber, increasing by 25%, 5%, and 22% at the period of 14 d, respectively. Because of excellent removal efficiency and non-toxicity, enhanced wash with saponin and HAS might be considered in the future design of full-scale remediation processes of diesel contaminated soil.
60. 题目: Biochar increases soil organic carbon, avocado yields and economic return over 4 years of cultivation
The use of biochar in avocado orchard soils has not yet been investigated in rigorous scientific experiments. We determine the effect of wood biochar on avocado growth, fruit production and economic benefit. Biochar was applied at 0%, 5%, 10% and 20% volume by volume basis. Biochar significantly improved the growth of avocado seedlings and increased fruit yield in the first three years after planting. There was an overall increase in soil carbon, fruit yield, tree diameter and height in all biochar treatments relative to the control over the seasons. Trees planted with biochar had 18–26% greater growth rates (in terms of height and stem diameter) than the control. Tree diameter was significantly greater with biochar (145.4 ± 3.3 mm) relative to the control treatment (125.0 ± 2.7 mm). Tree height was also significantly greater with biochar (3.7 ± 0.1 m) relative to the control treatment (3.4 ± 0.1 m). The fruit count from the biochar row was significantly greater (97%) in 2018. Heavy bearing trees typically have a lower yield in the subsequent year but despite this, the 2019 fruit counts were higher in aggregate for the biochar amended trees (20%) relative to the control. A cost-benefit analysis indicated that if yield surplus of fruit trees continued for three years, and assuming avocado prices remain at similar levels, then the discounted net benefit over a hectare would amount to US$8581, or US$105 per metric tonne of biochar applied.