12921. 题目: Evaluating co-emissions into indoor and outdoor air of EC, OC, and BC from the in-home biomass burning
Biomass burning constitutes a major source of ambient PM2.5 but also a predominant source of indoor PM2.5. Carbonaceous matter, including organic carbon (OC), elemental carbon (EC), black carbon, and brown carbon (BrC), are major components of PM2.5 and are of broad concern due to their impacts on health and climate patterns. In this study, we took simultaneous indoor and outdoor emission measurements to quantify pollutant emission factors (EFs) of carbonaceous matters, including the stack and fugitive EFs, from the real-world biomass burning in rural households. Modified combustion efficiency, fuel moisture, burning rates, and chimney gas velocity explained 45–71% of variations in the field-based emission factors. BrC (measured at 370 nm, and estimated based on the specific attenuation coefficients-16.6 m2/g at 880 nm and 39.5 m2/g at 370 nm)) comprised up to ~20% of all OC. Fractions of fugitive emissions of the total reached as high as 44–48%. Fugitive emissions would result in very high peak concentrations of approximately tens of mg/m3, leading to severe indoor air pollution. The study clearly demonstrates that the simultaneous study of indoor and outdoor emissions and air quality is crucial to understand mechanisms of the environmental impacts of internal combustion sources.
12922. 题目: Linking absorptive roots and their functional traits with rhizosphere priming of tree species
Woody plant roots can be classified into absorptive roots and transport roots based on root functions, order and traits. While there is an emerging view that living roots actively affect soil organic carbon (SOC) decomposition via the rhizosphere priming effect (RPE), the linkages of the RPE with C allocation to absorptive roots (relative to total roots) and their functional traits across soils are virtually unknown. Here, we investigated the RPE by growing a tree species (Chinese fir, Cunninghamia lanceolata) in three isotopically-distinct C4 soil types with different soil properties such as C/nitrogen (N) ratio and texture, and by growing three tree species (Chinese fir, larch (Larix kaempferi) and ash (Fraxinus mandshurica)) with wide variations in root functional traits in one of the C4 soils. We classified living roots into absorptive roots (first and second orders) and transport roots (third and higher orders) and then quantified their C allocation (relative to total roots) and morphological and chemical traits associated with economic construction, rhizodeposition and resource acquisition. We found that the RPE of Chinese fir across the three soils decreased with an increase in soil C/N ratio. This result conflicted with the N mining hypothesis and suggests that soil C stabilization mechanisms associated with clay minerals may play an important role. Further, significant differences in the RPE among tree species were largely accounted for by the C allocation to absorptive roots. Moreover, there was a significantly negative relationship between specific surface area of absorptive roots and the specific RPE (per unit biomass of absorptive roots) among tree species, suggesting that absorptive root traits shaping the extent of the rhizosphere may regulate the RPE. Taken together, our results provide evidence that absorptive roots play a predominant role in causing the RPE. These findings present an important step toward improving our capability to predict plant effects on SOC decomposition through linking the RPE to absorptive root functional traits.
12923. 题目: Organic amendments change soil organic C structure and microbial community but not total organic matter on sub-decadal scales
Organic C has many benefits for soil, but it is depleted by tillage and crop harvest, and especially so for biofuel crops. Accordingly, strategies such as partially retaining stover or planting a cover crop can help ameliorate the negative effect of C removal. We used a long-term field experiment to study the impacts of stover retention and planting a cover crop on soil organic matter (SOM), its extractable components, and the soil microbial community. SOM chemical composition characterization was determined by electrospray ionization (ESI) coupled with Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR-MS) in sequential water, methanol (MeOH), and chloroform (CHCl3) extracts. The characteristics of the soil bacterial community were measured by phospholipid fatty acid (PLFA), real-time quantitative PCR, and 16S rRNA gene sequence. The variations in total SOM content, total microbial biomass, and bacterial population were slight among treatments, but SOM chemical compounds, arbuscular mycorrhizal fungi (AMF) biomass, and bacterial structure changed significantly, and especially so in the coupled application of stover retention and cover crop. Specifically, stover retention enriched more lignin-like compounds in soil, whereas cover crop enriched more condensed hydrocarbons, and had more compounds with an aromaticity index (AI) > 0.5. The bacterial community was not altered by the cover crop, but the corn stover retention increased the relative abundances of Myxococcales (Deltaproteobacteria) and decreased that of Actinobacteria. Redundancy analysis (RDA) further revealed that the bacterial community in the stover treatments had a significant positive association with CHCl3-extracted chemical classes, i.e. unsaturated hydrocarbons and lipids, with the coupled application (stover and cover crop), and lignin and proteins with the corn stover only treatment. Taken together, our study shows how different C addition practices influence the molecular composition of SOM and the structure of soil microbial communities.
12924. 题目: Effects of manure on topsoil and subsoil organic carbon depend on irrigation regimes in a 9-year wheat-maize rotation
On the North China Plain, low soil organic carbon (SOC) content and a consistently dropping underground water level are seriously threatening food production security. To date, the interactive effect of fertilization types and irrigation regimes on surface and subsurface SOC contents has rarely been quantified. Here, we conducted a field study of three irrigation regimes with two fertilization types between 2009 and 2018. The three irrigation regimes included presowing irrigation (W0); presowing and jointing irrigation (W1); and presowing, jointing and anthesis irrigation (W2). The two fertilization types were mineral fertilizer only (CF) and mineral fertilizer plus composted chicken manure (CFM). Soil samples were collected from a depth of 0−100 cm in 20-cm increments to measure SOC and its composition, including labile pool I (LPI) (polysaccharides), labile pool Ⅱ (LPⅡ) (cellulose), and recalcitrant pool (RCP). Four SOC-related enzymes were determined, i.e., α-glucosidase, β-glucosidase, peroxidase and polyphenol oxidase. Stable carbon isotopic (13C) analysis was determined to distinguish the contributions of wheat- and maize-derived SOC in a wheat-maize rotation. The results showed that the 0−20-cm SOC content was highest in the W0 + CFM treatment. In the 0−20-cm layer, SOC decreased from W2 to W1 or W0 under CF, which is attributed to a reduction in the labile pool and maize-derived C and higher polyphenol oxidase. Conversely, under CFM, the 0−20-cm SOC content increased following decreased irrigation from W2 to W1 and from W1 to W0, mainly due to the increased LPⅡ and RCP. Compared with CF at W0 and W1, the 0−20-cm SOC content increased by 30.5 % and 21.8 % under CFM, respectively. Relative to the 0−20-cm soil layer, the SOC stock was larger in the 20−100-cm layer, which of the treatments had a variation manner similar to the 0−20-cm soil layer. Our results suggest that reduced irrigation regimes have significantly reduced the SOC stock and altered its composition in the 0−100-cm soil layer under CF and that CFM can increase the SOC stock in this layer when reducing the irrigation regime.
12925. 题目: A comparative techno-economic assessment of biochar production from different residue streams using conventional and microwave pyrolysis
A comparative techno-economic assessment and Monte Carlo risk analysis is performed on large scale (3 tonne/h) biochar production plants for conventional (CPS) and microwave (MWP) pyrolysis using six different residue streams. Both plants are viable with minimum selling prices between € 436/tonne and € 863/tonne for CPS, and between € 564/tonne and € 979/tonne for MWP. The CPS is therefore more viable than MWP as it is a simpler and more established technology. However, a 20 % biochar price increase due to higher biochar quality makes the MWP technology more viable. Nevertheless, the discounted payback period remains higher than this of CPS due to the increased CAPEX. Biochar price is the most important determinant of a biochar production plant's feasibility, motivating the need for economic and market research on biochar prices in function of biochar characteristics to reduce fluctuations in widely varying biochar prices.
12926. 题目: An abundant porous biochar material derived from wakame (Undaria pinnatifida) with high adsorption performance for three organic dyes
In this study, an activated wakame biochar material (AWBM) was prepared by a one-step calcination and activation method, whose adsorption performances for methylene blue (MB), Rhodamine B (RB) and malachite green (MG) were also analyzed. The results showed AWBM was a mesoporous fluffy structure material with a higher specific surface (1156.25 m2/g), exhibiting superior adsorption capacities for MB (841.64 mg/g), RB (533.77 mg/g) and MG (4066.96 mg/g), respectively. In addition, FT-IR analysis showed that AWBM possessed abundant active groups (such as -OH, -CO and -CH), further enhancing the adsorption efficiencies. The Langmuir model could better fit the three dyes adsorption isotherms process using AWBM, and the Pseudo-second-order model could better describe the adsorption kinetic experimental data. The thermodynamic analysis showed that the three dyes adsorption using AWBM was spontaneous endothermic reaction. This study suggests AWBM has enormous potential in the application of removing organic dyes from wastewater.
12927. 题目: Impact of trophic levels on partitioning and bioaccumulation of polycyclic aromatic hydrocarbons in particulate organic matter and plankton
The distribution and bioconcentration of polycyclic aromatic hydrocarbons (PAHs) in water, suspended particulate material (SPM), algae, and zooplankton samples from the Pearl River Delta (PRD), South China, were investigated. The PAHs in the water and SPM samples is significantly associated with chlorophyll a (Chl a), implying the important role of the aquatic productivity on PAH distribution. PAHs in the water or SPM samples were strongly correlated to dissolved organic carbon (DOC) or algal particulate organic carbon (A-POC). Moreover, the log bioconcentration factor (BCF) values (mL g−1) of PAHs in both the algae and zooplankton samples were linearly related to their log octanol-water coefficient (Kow) values. However, the slopes of these relationships were negatively correlated with Chl a, attributing to the difference in the dominant plankton species or the non-equilibrium exchange between air-water-biota. The above results indicate the important role of trophic levels on the distribution and bioaccumulation of PAHs.
12928. 题目: Fractions and mineralization potential of the sediment organic nitrogen in Daya Bay, South China Sea: Anthropogenic influence and ecological implications
Nitrogen mineralization is a critical biogeochemical process that transfers organic nitrogen into inorganic forms using heterotrophic microorganisms. However, few studies have focused on this potential nutrient supplier. In this study, the composition of sediment organic nitrogen (SON) was studied, and nitrogen mineralization flux entering the water column was quantified. The results indicate that acid-hydrolyzable nitrogen (AHN) accounts for more than 40% of the SON, especially in the riverine input and marine aquaculture areas, which had significantly higher concentrations than the bay mouth area. Similar results were found for the ammonium nitrogen (AN), amino-sugar nitrogen (ASN), the total hydrolyzable amino acid (THAA), and unidentified hydrolyzable nitrogen (HUN). The mineralization rate in the marine aquaculture area was as high as 9.03 ± 1.33 mg·kg−1·d−1, while those of the riverine input (4.77 ± 1.55 mg·kg−1·d−1) and bay mouth (5.12 ± 1.42 mg·kg−1·d−1) areas were lower. The SON fractions, including the AHN, AN, ASN, and AAN, could obviously affect the mineralization of the SON. However, the extracellular enzymes, including proteinase and urease, are the predominant factors controlling the SON mineralization process. Anthropogenic activities, including riverine input and marine aquaculture, exert significant influences on the fractions and mineralization of the SON, and thus, they may increase the amount of dissolved inorganic nitrogen in the bottom of the water column in Daya Bay.
12929. 题目: Metal concentration and its ecological risk assessment in the beach sediments of Coromandel Coast, Southern India
The present study investigates the concentration of acid leachable trace metals (ALTMs) and their ecological risk in the beach sediments of Coromandel Coast, Southern India. In total, thirty-six beach sediments (eighteen samples from low tide and eighteen samples from high tide) were collected from the study area. The results of the study of the ALTMs suggest that the sediments are enriched by natural processes with significant anthropogenic influences. The distribution of ALTMs in beach sediments is in the following descending order: Fe > Cr > Mn > Pb > Ni > Cu > Co > Zn. The statistical results indicate that the metal concentrations were chiefly originated from natural processes such as leaching, weathering, and fluvial action. In addition, the textural characteristics, organic matter, and calcium carbonate percentage play an important role in the distribution of metals in the beach sediments.
12930. 题目: Purifying effect of biochar-zeolite constructed wetlands on arsenic-containing biogas slurry in large-scale pig farms
To explore the purifying effect of vertical subsurface flow constructed wetlands (CWs) on arsenic-containing biogas slurry in pig farms under natural conditions in the field, vertical subsurface flow CWs with water spinach-Pennisetum sinese as the core was constructed in this study. Under the condition of biogas slurry with different dilution ratios (2, 4, 6; v/v) was fed to the wetlands and different substrates (biochar and zeolite) were added to the wetlands, respectively, the removal efficiency of the pollutants in biogas slurry by CWs were investigated. The enrichment of arsenic (As) in wetland substrates and three wetland plants (water spinach, green Pennisetum sinese and purple Pennisetum sinese) was analyzed. The results showed that, the removal rate of ammonia nitrogen (NH4+-N) in biogas slurry at low dilution ratio was always higher in the CWs, while that of total phosphorus (TP), chemical oxygen demand (COD) and As was higher in biogas slurry at high dilution ratio at first and then was just the opposite. The addition of zeolite and biochar could enhance the decontamination effect of CWs. Zeolite had better removal effect on NH4+-N, TP and COD, while biochar showed better removal effect on As. At low dilution ratio, the enrichment of As was high in the wetland sediments and three wetland plants. Adding biochar and zeolite increased the enrichment and absorption of As by sediments, water spinach and purple Pennisetum sinese, which was more significant by adding zeolite than biochar. However, they slightly reduced the absorption of As by green Pennisetum sinese. The detailed effluent quality assessment showed TP and NH4+-N to be significant pollution factors. The CWs treated with zeolite showed a higher purifying effect, while the CWs added without the two substrates had a lower purifying effect. This study provides a theoretical basis for the practical application of CWs in livestock and poultry wastewater treatment.
12931. 题目: Fe/Al (hydr)oxides engineered biochar for reducing phosphorus leaching from a fertile calcareous soil
Excessive input of phosphate fertilizer into agricultural soils has caused critical environmental concerns due to high phosphorus (P) accumulation in farmland and P leaching into subsurface drainage. In this study, an Fe/Al (hydr)oxides modified biochar (FA-BC) was fabricated from corn straw via a wet-precipitation method and utilized to reduce P leaching from a fertile calcareous soil. Spectroscopic techniques demonstrated that the FA-BC exhibited a higher oxidation resistance than the raw BC due to oxide impregnation on the BC surface. The maximum Langmuir P adsorption capacities (393 and 528 mg kg−1) of the BC (4%, w/w) and FA-BC (4%, w/w) treated soils demonstrated a more efficient P adsorption capacity of the FA-BC. Application of the 2% (w/w) FA-BC also significantly reduced the leaching of total P (81.3%) from the soil column, while maintained an appropriate level of bioavailable P in the soil for sustaining plant growth. The chemical sequestration test and in-situ P k-edge XANES analyses of the FA-BC incubated soils revealed that the labile Ca–P fractions were transformed into stabilized Fe/Al–P complexes. The increased soil pH, a higher degree of soil P saturation, and intensive interaction between P and Fe/Al (hydr)oxides also contributed to the superior ability of the FA-BC amended soils towards P retention. This study provided field-relevant implications for the design and application of engineered biochar for green and sustainable improvement of agricultural soils.
12932. 题目: Simultaneous adsorption and biodegradation of trichloroethylene occurs in a biochar packed column treating contaminated landfill leachate
Trichloroethylene (TCE) is a human carcinogen that is commonly found in landfill leachate. Contaminated leachate plumes may be intercepted prior to reaching groundwater and treated in situ using permeable reactive barriers (PRB). This study used a packed column system containing herbal pomace and spruce biochar, previously shown to have TCE adsorptive capabilities. Influent containing raw or autoclaved landfill leachate was used to investigate the potential for environmental micro-organisms to establish a TCE-dechlorinating biofilm on the biochar, in order to prolong the operational life span of the system. TCE removal ≥ 99.7 % was observed by both biochars. No dichloroethylene (DCE) isomers were present in the column effluents, but cis-1,2 DCE was adsorbed to the biochar treating raw landfill leachate, indicating that dechlorination was occurring biologically in these columns. Known microbial species that are individually capable of complete dechlorination of TCE to ethene were not detected by 16S rRNA gene sequencing, but several species capable of partial TCE dechlorination (Desulfitobacterium spp., Sulfurospirillium spp. and Desulfuromonas spp) were present in the biofilms of the columns treating raw landfill leachate. These data demonstrate that biochar from waste material may be capable of supporting a dechlorinating biofilm to promote bioremediation of TCE.
12933. 题目: Influence of palaeoclimate and hydrothermal activity on organic matter accumulation in lacustrine black shales from the Lower Cretaceous Bayingebi Formation of the Yin’e Basin, China
12934. 题目: Transient enhancement and decoupling of carbon and opal export in cyclonic eddies
12935. 题目: Linking soil engineers, structural stability, and organic matter allocation to unravel soil carbon responses to land-use change
12936. 题目: Sunlight-induced changes in naturally stored reclaimed water: Dissolved organic matter, micropollutant, and ecotoxicity
12937. 题目: Effects of elevation and slope aspect on the distribution of the soil organic carbon associated with Al and Fe mineral phases in alpine shrub–meadow soil
12938. 题目: Soil organic carbon and total nitrogen stocks as affected by vegetation types and altitude across the mountainous regions in the Yunnan Province, south-western China
12939. 题目: Influence of malonic acid and manganese dioxide on humic substance formation and inhibition of CO2 release during composting
12940. 题目: Negative Feedback by Vegetation on Soil Organic Matter Decomposition in a Coastal Wetland