论文检索

总访问量：5737813次

总访客量：393298人

所有论文

25161. 题目: No Evidence for Brown Carbon Formation in Ambient Particles Undergoing Atmospherically Relevant Drying
文章编号: N20012803
期刊: Environmental Science: Processes Impacts
作者: Vikram Pratap, Michael Battaglia Jr., Annmarie G Carlton, Christopher J Hennigan
更新时间: 2020-01-28
摘要: Recent laboratory studies have reported the formation of light-absorbing organic carbon compounds (brown carbon, BrC) in particles undergoing drying. Atmospheric particles undergo cycles of humidification and drying during vertical transport and through daily variations in temperature and humidity, which implies particle drying could potentially be an important source of BrC globally. In this work, we investigated BrC formation in ambient particles undergoing drying at a site in the eastern United States during summer. Aerosol BrC concentrations were linked to secondary organic aerosol (SOA) formation, consistent with seasonal expectations for this region. Measurements of water-soluble organic aerosol concentrations and light absorption (365 nm) were alternated between an unperturbed channel and a channel that dried particles to 41% or 35% relative humidity (RH), depending on the system configuration. The RH maintained in the dry channels was below most ambient RH levels observed throughout the study. We did not observe BrC formation in particles that were dried to either RH level. The results were consistent across two summers, spanning ~5 weeks of measurements that included a wide range of RH conditions and organic and inorganic aerosol loadings. This work suggests that mechanisms aside from humidification-drying cycles are more important contributors to ambient particle BrC loadings. The implications of this work on the atmospheric budget of BrC are discussed.

25162. 题目: Effect of soil organic matter (SOM) on the degradation of polycyclic aromatic hydrocarbons using Pleurotus dryinus IBB 903-A microcosm study
文章编号: N20012802
期刊: Journal of Environmental Management
作者: Abiram Karanam Rathankumar, Kongkona Saikia, Krishnakumar Ramachandran, Ramon Alberto Batista, Hubert Cabana, Vinoth Kumar Vaidyanathan
更新时间: 2020-01-28
摘要: Bioremediation of polycyclic aromatic hydrocarbons (PAHs) in soil matrix is often arbitrated by the presence of soil organic matter (SOM). The present study focuses on determining the effect of the soil organic content on the mycoremediation of two model PAHs, phenanthrene (Phe) and benzo(a) pyrene (BaP) through microcosm studies. On comparing various microcosm strategies, a maximum degradation of Phe (99%) and BaP (48.5%) in soil bioaugmented with Pleurotus dryinus IBB 903, followed by, biostimulation with the degradation of Phe (89.9%) and BaP (24.8%) were noted. On relating the degradation pattern with lignolytic enzyme cocktail production, a laccase activity of 108 U/Kg at day 21, aryl alcohol oxidase (411 U/Kg) and manganese peroxidase (52.2 U/Kg) at day 14 along with lignin peroxidase (481 U/Kg) at day 21 were noted in fungal augmented soils, which were comparatively higher than levels observed in the bio-stimulation. Investigating the impact of different concentration of SOM (3–12%), a maximum remediation of Phe by 100% at 9% SOM in days 28 and 58.19% for BaP at 12% SOM, respectively was exhibited. Further, the biosorption effect of PAHs in abiotic condition showed a positive correlation with the increase in SOM, with a maximum adsorption of 3.78% Phe, and 6.93% BaP. The results support that the nominal adsorption ability of SOM, and helps in enhancing the microbial growth, thereby improving their degradation potentials, when less than 6% of SOM was utilized. Overall, this work establishes the critical role of organic matter in the soil with reference by simultaneous stimulation and degradation capability in complete PAHs remediation.
图文摘要:

25163. 题目: Simultaneous adsorption and oxidation of antimonite onto nano zero-valent iron sludge-based biochar: indispensable role of reactive oxygen species and redox-active moieties
文章编号: N20012801
期刊: Journal of Hazardous Materials
作者: Dongning Wei, Bingyu Li, Lin Luo, Yongxin Zheng, Liuhui Huang, Jiachao Zhang, Yuan Yang, Hongli Huang
更新时间: 2020-01-28
摘要: The nano zero-valent iron sludge-based biochar (nZVI-SBC) was prepared in this study to eliminate Sb(III) from aqueous solutions, which was characterized by BET, SEM, XRD, TEM, FTIR, XPS. Our results proved that the incorporated nZVI on SBC matrix could significantly enhance eliminating Sb(III), and the max-adsorption capacity (160.40 mg g⁻¹) can be achieved at pH = 4.8 ± 0.2 and temperature of 298 K. The effect of co-existing anions and natural organic matters on the Sb(III) adsorption efficiencies were systematically investigated. The surface complexation is the possible adsorption mechanisms by FTIR and XPS. Furthermore, mechanistic investigation revealed that •OH and hydroquinone radical (H-SQ•⁻) could be the primary oxidants for the transformation of Sb(III) under oxic conditions, while 9,10-phenanthrene quinone radical (P-SQ•⁻) were responsible under anoxic conditions. Thus, the enhanced elimination of Sb(III) from aqueous solution was ascribed to the combined adsorption and oxidation. The potential engineering application of nZVI-SBC can be proved through three actual water matrix experiments, including lake water, river water and acid mine drainage. Our present findings proved that nZVI-SBC could be a potential adsorbent, given the excellent performance in the adsorption processes, as well as the toxicity alleviating ability and economic advantages, especially under sub-surface water.
图文摘要:

25164. 题目: Influence of inorganic additives on wheat straw composting: Characterization and structural composition of organic matter derived from the process
文章编号: N20012706
期刊: Journal of Environmental Management
作者: Jorge Medina, Carlos M. Monreal, Mónica Antilén, Marcela Calabi-Floody, Marta Velasco-Molina, Sebastián Meier, Fernando Borie, Pablo Cornejo, Heike Knicker
更新时间: 2020-01-27
摘要: Metallic oxides and clay minerals have gained increasing interest as additives of composting due to their influence in greenhouse gas emissions reduction and their effectivity in the stabilization of carbon both in compost and soils, leading to a cleaner compost production and potentially C sequestrant amendments. In this study, wheat straw (WS) was co-composted with iron oxide and allophanic soil and their influence on WS composting and composition of the end-products was evaluated. WS compost and their humic like-substances (HS) fraction were characterized by chemical and spectroscopic analyzes. After 126 days of process, the elemental composition showed slight differences of the N content for compost and HS, where the C/N atomic ratio tended to decrease relative to the initial material (WS; ~130). This trend was more pronounced in the HS from co-composted treatments (<30). The addition of inorganic materials increased the total acidity and phenolic-OH group contents (~15 and 14 mEq g⁻¹ respectively, iron oxide treatment) relative to the treatment without inorganic additives. Nevertheless, the FTIR and solid-state ¹³CNMR spectroscopy barely support the wet chemical analysis and revealed a similar final composition between all the studied compost treatments. These results suggest that the incorporation of these materials as compost additives had no major effect on the spectroscopic features of the end-products, however, critical changes of the properties such as the extractability, functionality and composition of HS were revealed by traditional methods. In conclusion, the supply of metal oxides and clays could impact the aerobic composting of WS favorizing the stabilization of certain C pools and adsorptive properties of the end-products, that is of importance in production of amendments suitable for being used in degraded and contaminated soils. Nevertheless, under the experimental conditions of our research C stabilization apparently depends of other mechanisms that still need to be elucidate.
图文摘要:

25165. 题目: Ultrafast sequestration of cadmium and lead from water by manganese oxide supported on a macro-mesoporous biochar
文章编号: N20012705
期刊: Chemical Engineering Journal
作者: Shunli Wan, Lian Qiu, Gui Tang, Weiyang Chen, Yan Li, Bin Gao, Feng He
更新时间: 2020-01-27
摘要: Porous carrier supported metal oxide composites possess significant potential for sequestration of heavy metals from various waters. However, slow diffusion of targeted metal ions within the micropores of the porous carriers is a key technical barrier limiting practical application of these hybrid adsorbents, particularly in high flow systems. In this study, we first synthesized a biochar with enlarged pore channel (namely K-BC) by adding KHCO₃ during the biochar pyrolysis process and then employed the K-BC as a supporter to fabricate a new manganese oxide-based composite (namely HMO-K-BC). It is striking that the effective intra-particle diffusion coefficient D of Pb(II) inside the K-BC is comparable to that in aqueous solution (1.5 × 10⁻⁶ v.s. 2.1 × 10⁻⁶ cm² s⁻¹). Although the D value of Pb(II) inside the HMO-K-BC was reduced to 1.8 × 10⁻⁷ cm² s⁻¹, it is still 1–2 orders of magnitude higher than that of conventional adsorbents such as activated carbon, ion exchanger and biochar. As a result, the HMO-K-BC can rapidly sequestrate Pb(II) and Cd(II) within 7.5 min. The HMO-K-BC can also selectively remove Pb(II) and Cd(II) in the presence of high level Ca(II) and humic acid. Column tests further showed that HMO-K-BC was able to effectively treat simulated and real Pb(II)- and Cd(II)-polluted wastewater in a high-flow system with superficial liquid velocity of 0.53 m h⁻¹ (20 BV h⁻¹). All the results manifest that expanding pores of biochar is a promising measure for promoting the practical application of biochar supported composites in wastewater treatment.
图文摘要:

25166. 题目: Organo-mineral complexes protect condensed organic matter as revealed by benzene-polycarboxylic acids
文章编号: N20012704
期刊: Environmental Pollution
作者: Zhaofeng Chang, Luping Tian, Fangfang Li, Min Wu, Christian E.W. Steinberg, Bo Pan, Baoshan Xing
更新时间: 2020-01-27
摘要: Condensed organic matters (COM) with black carbon-like structures are considered as long-term carbon sinks because of their high stability. It is difficult to distinguish COM from general organic matter by conventional chemical analysis, thus the contribution by and interaction mechanisms of organo-mineral complexes in COM stabilization are unclear and generally neglected. Molecular markers related to black carbon-like structures, such as benzene polycarboxylic acids (BPCAs), are promising tools for the qualitative and quantitative analysis of COM. In this study, one natural soil and two cultivated soils with 25 y- or 55 y-tillage activities were collected and the distribution characteristics of BPCAs were detected. All the investigated soils showed similar BPCA distribution pattern, and over 60% of BPCAs were detected in clay fraction. The extractable BPCA contents were substantially increased after mineral removal. The ratios of BPCA contents before and after mineral removal indicate the extent of COM-mineral particle interactions, and our results suggested that up to 73% COM were protected by mineral particles, and more stronger interactions were noted on clay than on silt. The initial cultivation dramatically decreased COM-clay interactions, and this interaction was recovered only slowly after 55-y cultivation. Kaolinite and muscovite are important for COM protection. But a possible negative correlation between BPCAs and reactive iron oxides of the cultivated soils suggested that iron may promote COM degradation when disturbed by tillage activities. This study provided a new angle to study the stabilization of COM and emphasized the importance of organo-mineral complexes for COM stabilization.
图文摘要:

25167. 题目: Nutrients release and greenhouse gas emission during decomposition of Myriophyllum aquaticum in a sediment-water system
文章编号: N20012703
期刊: Environmental Pollution
作者: Pei Luo, Xiong Tong, Feng Liu, Min Huang, Juan Xu, Runlin Xiao, Jinshui Wu
更新时间: 2020-01-27
摘要: Aquatic macrophytes play a significant role in nutrients removal in constructed wetlands, yet nutrients could be re-released due to plant debris decomposition. In this study, Myriophyllum aquaticum was used as a model plant debris and three debris biomass levels of 3 g, 9 g dry biomass, and 20 g fresh biomass (D3, D9, and F20, respectively) were used to simulate 120-d plant debris decomposition in a sediment-water system. The biomass first-order decomposition rate constants of D3, D9, and F20 treatments were 0.0058, 0.0117, and 0.0201 d⁻¹, respectively with no significant difference of decomposition rate among three mass groups (p > 0.05). Plant debris decomposition decreased nitrate and total nitrogen concentrations but increased ammonium, organic nitrogen, and dissolved organic carbon (DOC) concentrations in overlying water. The parallel factor analysis confirms that three components of DOC in overlying water changed over decomposition time. Emission fluxes of methane and nitrous oxide in the plant debris treatments were several to thousands of times higher than the control group within the initial 0–45 d, which was mainly attributed to DOC released from the plant debris. Plant debris decomposition can affect the gas emission fluxes for relatively shorter time (30–60 d) than water quality (>120 d). The 16S rRNA, nirK, nirS and hazA gene abundance increased in the early stage for plant debris treatments, and then decreased to the end of 120-d incubation time while ammonia monooxygenase α-subunit A gene abundance of ammonia-oxidizing archaea and bacteria had no large variations during the entire decay time compared with no plant debris treatment. The results demonstrate that decomposition of M. aquaticum debris could affect greenhouse gas emission fluxes and microbial gene abundance in the sediment-water system besides overlying water quality.
图文摘要:

25168. 题目: Biochar is superior to lime in improving acidic soil properties and fruit quality of Satsuma mandarin
文章编号: N20012702
期刊: Science of The Total Environment
作者: Songwei Wu, Ying Zhang, Qiling Tan, Xuecheng Sun, Wenhua Wei, Chengxiao Hu
更新时间: 2020-01-27
摘要: A better understanding is required for using biochar as an alternative option to lime materials for sustainable amelioration of soil acidity and improvement of fruit quality in acidic soils. In this study, a pot experiment was conducted to investigate the comparative effects of biochar (three different dosages of biochar, 1%, 2% and 4%, were denoted by BC-1, BC-2 and BC-3, respectively) and lime (three different dosages of lime, 1.2, 2.4 and 3.6 g kg⁻¹, were denoted by L-1, L-2 and L-3, respectively) on soil properties and fruit acidity of Satsuma mandarin. The decreased rates of fruit titratable acid (TA) by BC-1, BC-2 and BC-3 were 16.18%, 25.00% and 14.71%, which were higher than those by L-1, L-2 and L-3 were 11.76%, 16.18% and 5.88%. Moreover, the increased rates of fruit total soluble solid (TSS)/TA were 14.94%, 31.73%, 28.04% by BC-1, BC-2 and BC-3, but were 11.42%, 21.77%, 10.15% by L-1, L-2 and L-3, suggesting that biochar had better effects on improving fruit quality. Acidic soil properties were improved by biochar and lime, but biochar had better amelioration effects, as evidenced by soil-treated with BC-2 and BC-3 had greater increases of soil pH, soil respiration (SR) and microbial metabolic quotient, activities of soil urease (SU), invertase (SI), catalase (CAT) and cellulose (SC), and concentrations of soil phosphorus (P), potassium (K) and magnesium (Mg). Principal component analysis showed that soil pH, SR, SU, SI and CAT were main contributors to the differences of improvement effects of biochar and lime. Correlation analysis showed that fruit TA had negative relationships with soil pH, SU, SI, CAT, SC and soil P, K, Mg. This study indicates that the better effects of biochar on improving fruit quality of Satsuma mandarin were associated with the greater effects of it on improving acidic soil properties.
图文摘要:

25169. 题目: Influence of laccase treatment on fouling layer formation in ultrafiltration of birch hot-water extract
文章编号: N20012701
期刊: Separation and Purification Technology
作者: Tiina Virtanen, Jussi Lahti, Anna Kalliola, Tarja Tamminen, Mika Mänttäri, Mari Kallioinen
更新时间: 2020-01-27
摘要: Fouling problems caused by lignin have been limiting the use of membranes in the recovery of value-added materials from biorefinery streams. Fortunately, laccase-based catalytic pretreatments enable modification of lignin to the less fouling form. Because the mechanisms behind the fouling caused by ligneous compounds in wood-based streams are still not deeply understood, the aim of this study was to find out how laccase oxidation affects membrane fouling caused by pressurized hot-water extract. The effect of laccase on the fouling tendency of birch extract was explored both with adsorptive and pressure-driven experiments. The results suggested that laccase treatment increased the molar mass of lignin and improved significantly filtration capacity of commercial polyethersulphone membrane, possibly due to formation of less dense foulant layer during the filtration. Based on FTIR and BET results laccase oxidation decreased both adsorptive and pressure-driven fouling caused by lignin. However, decreases in pure water permeabilities were higher for the samples that were fouled with laccase treated extract. This may have originated from the transformation in the fouling mechanism from the pore narrowing to the pore blocking and could be prevented by the selection of a membrane with a different pore size.
图文摘要:

25170. 题目: Remediation of organic arsenic contaminants with heterogeneous Fenton process mediated by SiO 2 -coated nano zero-valent iron
文章编号: N20012607
期刊: Environmental Science and Pollution Research
作者: Yuancai Lv, Siyi Huang, Guofu Huang, Yifan Liu, Guifang Yang, Chunxiang Lin, Gao Xiao, Yonghao Wang, Minghua Liu
更新时间: 2020-01-26
摘要: Given their considerable solubility in water and potentially high toxicity to human health, organoarsenic compounds have become an emerging contaminant. Herein, a heterogeneous Fenton process mediated by SiO₂-coated nano zero-valent iron (SiO₂-nZVI) was employed to simultaneously remove the p-arsanilic acid (p-ASA, a typical organoarsenic compound) and the released arsenic. The initial pH value significantly influenced on the degradation of p-ASA and at the optimal pH (3.0), p-ASA (10 mg L⁻¹) could be completely oxidized to As(V), NH₄⁺, and plentiful phenolic compounds such as phenol and p-hydroquinone via the cleavage of C–N and C–As bonds within 60 min in pure water. Meanwhile, although the formed lepidocrocite and magnetite on the surface of SiO₂-nZVI significantly limited the reutilization, they played a vital role in the adsorption of the released As(V) and the residual arsenic levels in the effluent were as low as 0.031 mg L⁻¹, meeting both the drinking water standard of the World Health Organization (WHO) and the surface water standard of China (0.05 mg L⁻¹). Furthermore, high-level dissolved organic matters (DOM) (> 2 mg C L⁻¹) exhibited strong interference with both the oxidation of p-ASA and adsorption of arsenic, but the interference could be eliminated by increasing the SiO₂-nZVI dosage or adding H₂O₂. Importantly, this system could completely remediate p-ASA in a short time and simultaneously avoid the secondary pollution caused by inorganic arsenic, which was significant for the remediation of organoarsenic pollutants in swine wastewater.

25171. 题目: Effect of Biochar and Coal Fly Ash Soil Amendments on the Leaching Loss of Phosphorus in Subtropical Sandy Ultisols
文章编号: N20012606
期刊: Water, Air, & Soil Pollution
作者: Nadeesha L. Ukwattage, Yuncong Li, Yandong Gan, Tiantian Li, Ranjith P. Gamage
更新时间: 2020-01-26
摘要: Leaching of phosphorus fertilizer from loose-structured subtropical soils is a major course of agricultural water pollution in southeastern USA. Soil amendments play a major role in the phosphorus retention in soil through different mechanisms. In the present study we tested the effect of two soil amendments; biochar and coal fly ash in immobilizing the soluble phosphorus fertilizer added to sandy Ultisol soils from subtropical USA. Column leaching tests were conducted with Ultisol soil added with biochar (from avocado branch cut biomass) and coal fly ash at 5 tons/ha rate, under simulated rainfall, to collect the leachate over five pore volumes. The leachate was analyzed for the phosphate phosphorus content. In the end, the soil columns were carefully extracted, sectioned and analyzed for the total phosphorus, after acid digestion. Results showed 50% and 6% drop of soluble phosphorus leaching loss in biochar and coal fly ash added soil respectively. Soil amendments have shifted the loosely bound phosphorus into the Ca/Mg bound and Al/Fe/Mn bound pools which are not readily water extractable. Addition of biochar and coal fly ash together showed a synergistic interaction effect in reducing the leaching loss of phosphorus which needs further investigation to understand the exact mechanism.

25172. 题目: Sensitivity analysis of agricultural inputs for large-scale soil organic matter modelling
文章编号: N20012605
期刊: Geoderma
作者: Julius Diel, Uwe Franko
更新时间: 2020-01-26
摘要: The dynamics of Soil Organic Matter (SOM) and its relation to the carbon and nitrogen cycle affect many environmental problems (e.g. climate change, food security and water quality). The development of adaptation strategies requires model predictions, but for the necessary large-scale SOM dynamic studies, the quality of the input data is often limiting the reliability of the results.So we performed a uncertainty and sensitivity analysis at different sites of the federal state of Saxony, Germany, and assessed the importance of aggregated agricultural data, namely organic amendments, crop yields, area share of by-product incorporation, area share of conservation tillage and initial soil organic carbon (SOC) concentration (p_oram, p_yield, p_bp, p_cons and p_soc respectively) on the result uncertainty by assuming an uniform error of ±10%. The agricultural data was regionalized from 717 long-term observation fields throughout the study region.We assessed the uncertainties of relative SOC stock change (ΔC_rel) and total nitrogen mineralisation from the organic matter (OM-N_min) and explored the changing sensitivities over the model period (1998–2014).Our results show that p_soc was the most important source of uncertainty for all sites of this study. For ΔC_rel, it is over the whole time constantly the by far most sensitive input parameter, with p_bp being the only factor of agricultural practice with some substantial influence on almost all sites. In the mountainous regions, p_cons ranks equal to p_bp, while for the sandy heathlands, none of them mark a substantial influence besides p_soc.For OM-N_min, p_soc loses its importance over time, being outranked by p_oram in the heathlands after 8 years and in the mountainous regions after 13 years. p_oram furthermore places second for all others but one other region, where p_cons is slightly more important. We therefore see the initial carbon content, the share of by-product removal, and the amount of organic amendments as those factors, where improved data quality would bring the highest effect to reduce the uncertainty in regional SOM modelling.

25173. 题目: Dynamic variation in nitrogen removal of constructed wetlands modified by biochar for treating secondary livestock effluent under varying oxygen supplying conditions
文章编号: N20012604
期刊: Journal of Environmental Management
作者: Likui Feng, Yang Liu, Jinyong Zhang, Cong Li, Haiming Wu
更新时间: 2020-01-26
摘要: Vertical flow constructed wetlands are facing the problem of low removal efficiency when treating high-load wastewater. This study explored the effect of oxygen supplement (1.2, 1.0, 0.8 L min⁻¹ for 6 h; 1.0 L min⁻¹ for 4 h and 2 h) on enhancing nitrogen removal in vertical flow constructed wetlands modified by adding biochar for treating secondary livestock effluent. The results indicated that biochar addition could enhance contaminant removal due to its adsorption of contaminants under the condition of no aeration. Additionally, the aeration addition of 1.0 L min⁻¹ for 2 h per day in biochar-based constructed wetlands achieved the high efficiencies for chemical oxygen demand (95%) and total nitrogen (73%) removal. However, total nitrogen removal efficiency in biochar-based constructed wetlands declined under excessive dissolved oxygen conditions which might restrain the denitrification process. Average nitrous oxide emission fluxes in biochar-based constructed wetlands (575–1877 μg m⁻² h⁻¹) were lower than those in non-biochar constructed wetlands (745–2298 μg m⁻² h⁻¹). In addition, the variation of N₂O emission under different aeration conditions was similar with the maximum value at the aeration condition of 1.2 L min⁻¹ for 6 h d⁻¹. These results could be useful for improving the sustainable design and operation of constructed wetlands for high-load wastewater treatments.
图文摘要:

25174. 题目: Mobility monitoring of two herbicides in amended soils: A field study for modeling applications
文章编号: N20012603
期刊: Journal of Environmental Management
作者: María J. Carpio, M. Sonia Rodríguez-Cruz, Carlos García-Delgado, María J. Sánchez-Martín, Jesús M. Marín-Benito
更新时间: 2020-01-26
摘要: This paper reports the mobility and total balance of chlorotoluron (CTL), flufenacet (FNC) and bromide ion (Br⁻) throughout a sandy soil profile after the application of spent mushroom substrate (SMS) and green compost (GC). Obtaining mobility dataset is crucial to simulate the herbicides' fate under amended soil scenarios by application pesticide leaching models with regulatory application (FOCUS models). The application of organic residues is nowadays increased to improve the crop yields and there is a gap in the simulations of this kind of amended scenarios. A two-year field experiment involving unamended soil (S) and SMS- or GC-amended soil plots was conducted. CTL, FNC, and Br⁻ were annually applied and their residual concentrations were determined in soil profiles (0–100 cm) regularly sampled. In all the treatments the order of mobility is followed as FNC < CTL < Br⁻. SMS and GC increased herbicide retention in the top 10 cm by the higher organic carbon (OC) content than the unamended soil, and their ability to increase the soil's water-holding capacity and to decrease water percolation. Simultaneously dissolved organic carbon (DOC) content facilitated herbicide transport being it favoured by the initial soil moisture content and the rainfall shortly after the chemicals' initial application. Over the first year, residual amounts (<2.6%) of Br⁻, CTL and FNC were leached down to 90–100 cm depth in the three treatments. However, over the second year low CTL and FNC amounts (<1.0%) reached the bottom layer only in S + SMS although high Br⁻ concentrations did so in the three treatments (<20%). According to the total balance of Br⁻, CTL, and FNC in the soil profiles other processes (degradation, mineralisation, bound residues formation, and/or crop uptake) different from leaching below 1 m depth might play a key role in their dissipation especially in the amended soil profiles. SMS and GC are likely to be used as organic amendments to preserve the soil and water quality but in the case of SMS, its higher DOC content could imply a higher potential risk for groundwater contamination than GC.

25175. 题目: How do earthworms affect organic matter decomposition in the presence of clay-sized minerals?
文章编号: N20012602
期刊: Soil Biology and Biochemistry
作者: J. Barthod, M.-F. Dignac, G. Le Mer, N. Bottinelli, F. Watteau, I. Kögel-Knabner, C. Rumpel
更新时间: 2020-01-26
摘要: Clay-sized soil minerals are known to protect organic carbon (OC) from mineralisation by formation of organo-mineral associations limiting its availability to microorganisms. The impact of soil fauna on these processes is poorly known. The aim of this study was to investigate the effect of earthworms on organic matter (OM) decomposition and association with minerals during a laboratory experiment. We used a model system consisting of fresh OM incubated with and without epigeic earthworms (Eisenia andrei and foetida) in presence of different types and amounts of phyllosilicates (kaolinite, montmorillonite) and an iron oxide (goethite) and combinations of these minerals. Our experimental setup included a high OM:mineral ratio to represent the soil-litter interphase. We monitored OC mineralization during 196 days. Additionally, we investigated physicochemical parameters and chemical OM characteristics of decomposition products by determination of water-soluble OC (WSOC) and acquisition of solid-state ¹³C NMR spectra. We also analysed microscale organisation of the organo-mineral associations produced with and without earthworms by transmission electron microscopy (TEM).Earthworms enhanced OC mineralisation in all treatments. They also led to greater reductions of OC emissions in the presence of minerals as compared to the mineral-free control, depending on the type and amount of minerals added. The presence of earthworms affected microbial biomass, the concentration of WSOC and increased the contribution of aromatic compounds to OM decomposition products. Microscale analyses by TEM showed that earthworms favoured association of minerals with partly degraded OM along with completely degraded material, while in absence of earthworms only completely degraded OM was associated with minerals. We conclude that earthworms impact OM decomposition through (1) their effect on microbial biomass and the physicochemical parameters of microbial habitat and (2) the formation of OM associations by changing the OM types associated to minerals and possibly by creating closer association of partly degraded OM and iron oxides. The stability of these associations remains to be investigated.

25176. 题目: Nitrogen dynamics affected by biochar and irrigation level in an onion field
文章编号: N20012601
期刊: Science of The Total Environment
作者: Suduan Gao, Dong Wang, Sadikshya R. Dangi, Yinghua Duan, Tom Pflaum, Jim Gartung, Ruijun Qin, Thomas Turini
更新时间: 2020-01-26
摘要: Soil amended with biochar has many potential environmental benefits, but its influence on the fate of nitrogen (N) under irrigated conditions is unclear. The objective of this research was to determine the effects of biochar and interactions with irrigation on N movement in soil, gas emissions, and leaching. A three-year study was conducted in an onion field with three main irrigation treatments (50, 75, and 100% of a reference that provided sufficient water for plant growth) and three biochar amendment rates (0 or control, low char - applied first year at 29 Mg ha⁻¹, and high char - added both first and second year for a total 58 Mg ha⁻¹) as sub-treatments in a split-plot design. Nitrogen fertilizer was applied three times during first year growing season, but weekly the second year. Ammonia (NH₃) volatilization, nitrous oxide (N₂O) emission, and nitrate (NO₃⁻) in soil pore water were monitored during growing season, and annual N (total and NO₃⁻) changes in soil profile were determined for first two years. Nitrate leaching was measured in the third year. Ammonia volatilization was affected by fertilization frequency with higher loss (5–8% of total applied) when fertilizer was applied in large doses during the first year compared to the second year (4–5%). Nitrous oxide emissions were ≤0.1% of applied N for both years and not affected by any treatments or fertilization frequency. Nitrate concentration in soil profile increased significantly as irrigation level dropped, but most of the NO₃⁻ was leached by winter rain. There was no significant biochar effect on total N gas emissions or soil NO₃⁻ accumulation, but significant irrigation effect and interaction with biochar were determined on soil NO₃⁻ accumulation. High leaching was associated with biochar amendment and higher irrigation level. Irrigation strategies are the key to improving N management and developing the best practices associated with biochar.
图文摘要:

25177. 题目: Fluorescence characteristics of particulate water-soluble Organic Compounds Emitted from coal-fired boilers
文章编号: N20012516
期刊: Atmospheric Environment
作者: Yanrong Yang, Juanjuan Qin, Ting Qi, Xueming Zhou, Rongzhi Chen, Jihua Tan, Kang Xiao, Dongsheng Ji, Kebin He, Xiaoting Chen
更新时间: 2020-01-25
摘要: The fluorescence characteristics of particulate water-soluble organic compounds (WSOC) emitted by different power of coal-fired boilers (A total of 14 boilers including 1, 2, 4, 6, 10, 15, 20 tons steam per hour (t·h−1)) in Lanzhou, an industrial city of northwest China, were analyzed by excitation-emission matrix (EEM) fluorescence spectroscopy. Results showed that the fluorescence profiles of WSOC in different power coal-fired boiler samples had certain similarities, reflecting the consistency of the fluorophore structures in the coal-originated WSOC. In general, the main excitation (Ex) and emission (Em) wavelength ranges of fluorescence peaks generated by WSOC were λEx = 230–250 nm and λEm = 360–430 nm. Since the fluorophore of WSOC was mainly concentrated in the fluorescent regions II and III, the main components in the fluorophore were tryptophan-like, fulvic acid and humic-like substances. Humification index (HIX), fluorescence index (FI) and freshness index (BIX) were 0.36 ± 0.36, 2.09 ± 0.42 and 1.02 ± 0.30, respectively. It may indicate that the particulate WSOC had a lower degree of humification and lower aromaticity. In the range of larger Stokes shift (λEx−1-λEm−1 ≥ 1.2 μm−1), the normalized fluorescence intensity of WSOC showed the largest peak, suggesting that there may be many hydrophobic substances containing a large number of π-conjugated systems in WSOC. These findings are not only conducive to cognize the optical characteristics of particulate matter emitted from coal-fired pollution sources, but also help to consummate the spectral characteristics of coal-fired pollution sources.

25178. 题目: Unrecognized Contributions of Dissolved Organic Matter Inducing Photodamages to the Decay of Extracellular DNA in Waters
文章编号: N20012515
期刊: Environmental Science & Technology
作者: Xin Zhang, Jing Li, Mu-Cen Yao, Wen-Yuan Fan, Chuan-Wang Yang, Li Yuan, Guo-Ping Sheng
更新时间: 2020-01-25
摘要: Extracellular DNA (eDNA), which is derived from lysis or secretion of cells, is ubiquitous in various environments and crucial for gene dissemination, bacterial metabolism, biofilm integrity, and aquatic monitoring. However, these processes are largely influenced by damage to eDNA. Photodamage to eDNA, one of the most important types of DNA damage in natural waters, thus far remains unclear. In particular, the roles of the ubiquitous dissolved organic matter (DOM) in this process have yet to be determined. In this study, eDNA photodamage, including both deoxynucleoside damage and strand breaks, proved to be significantly influenced by DOM. DOM competed with eDNA for photons to inhibit the direct photodamage of eDNA. Nevertheless, DOM was photosensitized to produce reactive oxygen species (ROS) (i.e., hydroxyl radicals (·OH) and singlet oxygen (1O2)) to enhance the indirect photodamage of eDNA. The ·OH induced damage to four deoxynucleosides and strand breaks, and the 1O2 substantially enhanced deoxyguanosine damage. The presence of DOM changed the main photodamage products of deoxynucleosides, additional oxidation products induced by ROS formed besides pyrimidine dimers caused by UV. Results indicate that DOM-mediated indirect photodamage contributed significantly to eDNA photodamage in most water bodies. This study revealed the previously unrecognized crucial role of DOM in the decay of eDNA in waters.

25179. 题目: Paleo-environmental evidence of ecosystem change in Lake St. Clair region of Laurentian Great Lakes basin: contrasting responses to land-use change and invasive mussels
文章编号: N20012514
期刊: Journal of Paleolimnology
作者: Melissa M. Baustian, Yolanda M. Brooks, Mark Baskaran, Peter R. Leavitt, Bo Liu, Nathaniel Ostrom, R. Jan Stevenson, Joan B. Rose
更新时间: 2020-01-25
摘要: The Laurentian Great Lakes have been subject to substantial modification from diverse anthropogenic stressors, including nutrient enrichment, climate change, chemical and biological pollutants, and invasive species, yet little is known of the relative historical influence of these factors. Here we analyze diverse fossil metrics from vibracores at two sites, a bay area (Anchor Bay) and a tributary (Clinton River) in the Lake St. Clair ecosystem to determine the ecological responses from land-use practices and invasive mussel invasions. Sediment cores spanning over 100 years indicated that the expansion of non-native Dreissena polymorpha and Dreissena rostriformis (dreissenid mussels) into Anchor Bay site after the mid-1990s was associated with ~ 60 to 95% reduction in algal and cyanobacterial abundances and twofold increase in sedimentary organic matter (SOM) and bioavailable phosphorus. These increases in SOM and bioavailable phosphorus are relatively similar to increases inferred from the late nineteenth century when large portions of the watershed were cleared and drained for agriculture. In contrast, the Clinton River site experienced a continuous increase in the influx of nutrients, organic matter, and elevated sedimentary phototrophic pigments during the twentieth century and into the twenty-first century. Site comparisons suggest different mechanisms inducing changes in primary production varied, where Anchor Bay was mainly affected by the comparatively recent (since ca. mid-1990s) endogenous influence of invasive species, while the Clinton River site was primarily influenced by the input of exogenous anthropogenic nutrients over the past 100 years. These new findings illustrate that watershed management and policies within large lakes with multi-jurisdictional (national) Area of Concerns should consider site-specific regulatory mechanisms.

25180. 题目: Different carboxyl‐rich alicyclic molecules proxy compounds select distinct bacterioplankton for oxidation of dissolved organic matter in the mesopelagic Sargasso Sea
文章编号: N20012513
期刊: Limnology and Oceanography
作者: Shuting Liu, Rachel Parsons, Keri Opalk, Nicholas Baetge, Stephen Giovannoni, Luis M. Bolaños, Elizabeth B. Kujawinski, Krista Longnecker, YueHan Lu, Elisa Halewood, Craig A. Carlson
更新时间: 2020-01-25
摘要: Marine dissolved organic matter (DOM) varies in its recalcitrance to rapid microbial degradation. DOM of varying recalcitrance can be exported from the ocean surface to depth by subduction or convective mixing and oxidized over months to decades in deeper seawater. Carboxyl‐rich alicyclic molecules (CRAM) are characterized as a major component of recalcitrant DOM throughout the oceanic water column. The oxidation of CRAM‐like compounds may depend on specific bacterioplankton lineages with oxidative enzymes capable of catabolizing complex molecular structures like long‐chain aliphatics, cyclic alkanes, and carboxylic acids. To investigate the interaction between bacteria and CRAM‐like compounds, we conducted microbial remineralization experiments using several compounds rich in carboxyl groups and/or alicyclic rings, including deoxycholate, humic acid, lignin, and benzoic acid, as proxies for CRAM. Mesopelagic seawater (200 m) from the northwest Sargasso Sea was used as media and inoculum and incubated over 28 d. All amendments demonstrated significant DOC removal (2–11 μmol C L⁻¹) compared to controls. Bacterioplankton abundance increased significantly in the deoxycholate and benzoic acid treatments relative to controls, with fast‐growing Spongiibacteracea, Euryarcheaota, and slow‐growing SAR11 enriched in the deoxycholate treatment and fast‐growing Alteromonas, Euryarcheaota, and Thaumarcheaota enriched in the benzoic acid treatment. In contrast, bacterioplankton grew slower in the lignin and humic acid treatments, with oligotrophic SAR202 becoming significantly enriched in the lignin treatment. Our results indicate that the character of the CRAM proxy compounds resulted in distinct bacterioplankton removal rates of DOM and affected specific lineages of bacterioplankton capable of responding.