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23401. 题目: Warming alters fungal communities and litter chemistry with implications for soil carbon stocks
文章编号: N19021101
期刊: Soil Biology and Biochemistry
作者: Eric W. Morrison, Anne Pringle, Linda T.A. van Diepen, A. Stuart Grandy, J.M. Melillo, Serita D. Frey
更新时间: 2019-02-11
摘要: Rates of leaf litter decay are generally expected to accelerate with increasing temperature. However, chronic temperature elevation may cause changes in the quality of litter residues or in the composition of decomposer communities that result in unexpected decay responses. We performed a 23-month litter decomposition study at a long-term soil warming experiment to determine how soil warming affects litter decay rate, litter chemistry, extracellular enzyme activities, and fungal community composition. Experimental soil warming did not affect litter mass loss, but did result in a 23% increase in the relative abundance of lignin; a concomitant shift in enzyme activity wherein lignin-decomposing enzymes had higher activity in the heated treatment while cellulose-decomposing enzymes were suppressed; and a shift in the composition of the active fungal community. In particular, ectomycorrhizal fungi were three times more abundant in the heated treatment than the control, and shifts in fungal community composition were significantly correlated with the observed changes in extracellular enzyme activities. Our results suggest that warming altered the trajectory of decay resulting in litter residues enriched in lignin compounds and that were populated by a higher relative abundance of ectomycorrhizal fungi. These shifts may have altered the temperature sensitivity of litter decay by reducing the quality of litter residues and changing fungal community function.

23402. 题目: Elucidation of preferential elimination of Cr(VI) via bioinspired adsorbents: a comparative assessment
文章编号: N19021004
期刊: Environmental Earth Sciences
作者: Soumya Banerjee, Sanghamitra Barman, Gopinath Halder
更新时间: 2019-02-10
摘要: The present study investigates uptake of Cr(VI) from synthetic metal solution by superheated steam-activated biochar (SABC) made from roots of Colocasia esculenta and synthetic zeolite (ZRHA) prepared from rice husk ash under the influence of pH (1–7), adsorbent dose (1–100 mg/L), initial Cr(VI) concentration (5–190 mg/L), temperature (15–55 °C), agitation speed (100–170 rpm) for a contact time of 30–1440 min. ZRHA and SABC were able to remove metal ions from a stock solution of 90 and 110 mg/L of Cr(VI) with a removal of 85.89% and 94.8%, respectively. Metal ion adsorption onto zeolite ZRHA followed monolayer adsorption, whereas biochar SABC employed multilayer adsorption. Kinetic studies suggested that adsorption of Cr(VI) ions could follow both physisorption and chemisorption depending on the adsorbent used. The two-compartment dynamic model study revealed Cr(VI) adhesion followed a slow phase of adsorption which suggested intraparticle diffusion to be a prominent rate-limiting factor for both cases. The thermodynamic study claimed that Cr(VI) adsorption was a temperature dependent phenomenon. Instrumental studies by TEM, SEM, EDX and FT-IR also advocated their part on Cr(VI) removal. Also, crystallinity of both the adsorbents was determined from their XRD analysis. Thus, the current study promotes both ZRHA and SABC to be a promising adsorbent for Cr(VI) removal from contaminated aqueous solution.

23403. 题目: Drying and rewetting effects on organic matter mineralisation of contrasting soils after 36 years of storage
文章编号: N19021003
期刊: Geoderma
作者: Andrew R. Jones, Vadakattu V.S.R. Gupta, Scott Buckley, Richard Brackin, Susanne Schmidt, Ram C. Dalal
更新时间: 2019-02-10
摘要: Soil incubation studies commonly use archived, dry stored soil samples. Numerous studies have detected a profound impact of dry storage on soil microbial community composition and activity. However, comparatively few studies have explored the impact of storage on the short-term mineralisation of soil organic matter (SOM) after moistening dry soils to revive and stabilise microbial activity (“pre-incubation”). We examined whether pre-incubation of dry stored soil of contrasting texture (Alfisol and Vertisol) can recover native soil microbial functions in fresh soil or soil stored for 3 weeks, 3 or 36 years. The oldest samples had a delayed CO₂ response after moistening, but matched CO₂ production rates of younger samples within hours. The two soil types displayed contrasting CO₂ emission responses after moistening; the Alfisols had a rapid but short-lived CO₂ emission peak (the so-called “Birch Effect”) while the Vertisols demonstrated a long, sustained release of CO₂ reflecting its higher abundance of microsite abundance and microaggregates which may protect SOM and microorganisms during adverse conditions like drying. After 10 days of pre-incubation, older Alfisol samples had higher protease activity and response to amino acid addition demonstrating altered microbial physiological responses relating to nitrogen (N) compared to fresher counterparts. However, such responses in Vertisols were unchanged suggesting high clay soils with high potential microsite abundance may improve preservation of soil N functions through dry storage or even drought. This work highlights both limitations and possibilities of incubating dry archived soils for SOM mineralisation studies.

23404. 题目: Autoxidation of the sea ice biomarker proxy IPSO₂₅ in the near-surface oxic layers of Arctic and Antarctic sediments
文章编号: N19021002
期刊: Organic Geochemistry
作者: Jean-François Rontani, Lukas Smik, Simon T. Belt
更新时间: 2019-02-10
摘要: Over the last decade or so, the mono- and di-unsaturated highly branched isoprenoid (HBI) lipids IP₂₅ (Ice Proxy with 25 carbon atoms) and IPSO₂₅ (Ice Proxy for the Southern Ocean with 25 carbon atoms) have emerged as useful proxies for sea ice in the Arctic and Antarctic, respectively. A more complete understanding of their respective proxy signatures, however, requires more detailed knowledge of their stability in the water column and in sediments. In the current study, we focused on the autoxidation of IPSO₂₅, first by performing laboratory-based oxidation reactions on a purified sample and characterizing products based on detailed mass spectral analysis. We then analysed for the same oxidation products in near-surface sediments retrieved from the Arctic and the Antarctic, and some suspended organic matter from the Antarctic. Our data show that IPSO₂₅ is susceptible to partial autoxidation within the oxic layers of Arctic and Antarctic sediments, while the same processes appear not to be so important in the water column. Although the number of primary autoxidation reactions identified in sediments was not as large as in laboratory experiments, there was evidence for their subsequent modification by biotic degradation. Quantifying the extent of degradation of IPSO₂₅ and IP₂₅ in sediments, and thus the impact of such process on the use of these biomarkers as paleo sea ice proxies, remains challenging at this stage, since most of the primary oxidation products do not accumulate, likely due to secondary biodegradation reactions. Some interesting differences in reactivity were also observed between IPSO₂₅ and IP₂₅ present in the same Arctic sediments. This suggests that factors other than environmental control may influence the IPSO₂₅/IP₂₅ ratio (i.e. DIP₂₅) in Arctic sediments.

23405. 题目: Soil physical and mechanical attributes in response to successive harvests under sugarcane cultivation in Northeastern Brazil
文章编号: N19021001
期刊: Soil and Tillage Research
作者: Roberta Q. Cavalcanti, Mario M. Rolim, Renato P. de Lima, Uilka E. Tavares, Elvira M.R. Pedrosa, Igor F. Gomes
更新时间: 2019-02-10
摘要: Soil degradation due to agricultural field traffic is a serious issue affecting soil functions in modern agriculture. With sugarcane cultivation, the number of harvests through successive ratoons has become a challenge for the maintenance of soil quality in the topsoil and subsoil. The objective of this study was to evaluate physical and mechanical responses of soil to successive harvests under sugarcane cultivation in an Ultisol of coastal tablelands in Northeastern Brazil. Disturbed and undisturbed soil samples were collected from five sites at depths of 0–0.20 m (topsoil) and 0.20–0.40 m (subsoil), in which one, two, three or four harvests had taken place. In addition, one site had been kept without cultivation for one year after a sugarcane crop. Organic carbon (OC), maximum soil bulk density (BD_max), critical water content (w_c), degree of compaction (DC), precompression stress (σ_p), compression index (CI) and the angle of internal friction (φ) were measured and subjected to multivariate analyses for the different sugarcane ratoons. Soil compaction indicators and OC in the topsoil were sensitive to the number of harvests, where compaction and OC increased with each ratoon sugarcane crop. The increase in OC with successive harvests resulted in a decrease in the BD_max and an increase in the w_c, which suggest that optimum water content for compaction is moved to wetter zone due organic matter effects. The DC increased considerably after the third harvest, and it was at a maximum level before the sugarcane renovation (i.e. at the harvest immediately before the new seeding). In the subsoil, immediately below the plough layers, where plough pan formation typically occurs in conventional tillage, considerable changes in the soil physical and mechanical indicators are unlikely to occur due to the persistence of compacted layers. The increase in the organic carbon content results in better soil physical condition in the soil surface, but the degree of compaction may slightly increase due to frequency of traffic caused by the increase in the number of harvests, becoming compaction more severe close to the sugarcane renovation.

23406. 题目: Maize root‐derived C in soil and the role of physical protection on its relative stability over shoot‐derived C
文章编号: N19020910
期刊: European Journal of Soil Science
作者: Hui Xu, Bart Vandecasteele, Laura Zavattaro, Dario Sacco, Matthias Wendland, Pascal Boeckx, Geert Haesaert, Steven Sleutel
更新时间: 2019-02-09
摘要: Evidence is accumulating that belowground crop residues contribute more efficiently to the build‐up and maintenance of native soil organic carbon (SOC) than aboveground plant parts. We corroborated previous testing of the hypothesis that root‐C would preferentially accumulate in soil microaggregates where it is physically protected against microbially mediated decomposition. In three European field trials with C₃ to C₄ crop transitions, we compared the content of maize‐C (Zea mays L.) in soil from rotations with grain maize (MG) or silage maize (MS), i.e. with incorporation of roots and shoots or roots only. After decades of maize cultivation, SOC content did not differ within three out of four MS–MG pairs, although obviously larger amounts of shoot biomass were added to soil in the case of MG. We found that relative contribution of roots was on average 3.5 times more than shoots to the build‐up of SOC per equivalent mass of residue C added to soils. Preferential occlusion of root‐C as silt‐sized intra‐microaggregate particulate organic matter (iPOM) was not observed. There were much larger effects from shoot incorporation on maize‐C in the >53‐μm fraction and free silt and clay. Storage of root‐C as sand‐sized iPOM was not quantified here, but first estimates suggested that physical entrapment at this level could only partly explain the longevity of root‐C in soil. We reconfirm the relative stability of root‐C in soil, but do not conclude that this stems from preferential physical entrapment over shoot‐C. Future work should investigate the cause of preferential root‐C association with the clay‐sized fraction and if this occurs before or after microbial processing.

23407. 题目: Tracing organic carbon and microbial community structure in mineralogically different soils exposed to redox fluctuations
文章编号: N19020909
期刊: Biogeochemistry
作者: Pauline Winkler, Klaus Kaiser, Reinhold Jahn, Robert Mikutta, Sabine Fiedler, Chiara Cerli, Angelika Kölbl, Stefanie Schulz, Martha Jankowska, Michael Schloter, Cornelia Müller-Niggemann, Lorenz Schwark, Susanne K. Woche, Steffen Kümmel, Sri R. Utami, Karsten Kalbitz
更新时间: 2019-02-09
摘要: Submerged rice cultivation is characterized by redox fluctuations and results in the formation of paddy soils, often accompanied by soil organic carbon (SOC) accumulation. The impact of redox fluctuations and the underlying soil type on the fate of organic carbon (OC) in paddy soils are unknown. Hence, we mimicked paddy soil development in the laboratory by exposing two soil types with contrasting mineral assemblages (Alisol and Andosol) to eight anoxic–oxic cycles over 1 year. Soils regularly received ¹³C-labeled rice straw. As control we used a second set of samples without straw addition as well as samples under static oxic conditions with and without straw. Headspaces were analyzed for carbon dioxide and methane as well as their δ¹³C signatures, whereas soil solutions were analyzed for redox potential, pH, dissolved iron, and dissolved organic carbon (DOC and DO¹³C). At the end of the experiment, when eight redox cycles were completed, mineral-associated organic matter (MOM) was isolated by density fractionation and characterized for δ¹³C, non-cellulosic carbohydrates, and lignin-derived phenols. Moreover, changes in the soil’s microbial community structure were measured. For both soil types, headspace data confirmed less respiration in straw-amended soils with redox fluctuation than in those under static oxic conditions. The δ¹³C data revealed that, irrespective of soil type, straw carbon allocation into MOM was larger in soils with redox fluctuation than in those with static oxic conditions. A net increase in MOM after the one-year incubation, however, was only observed in the respective Andosol, probably due to abundant reactive minerals capable of OC uptake. In the Alisol, straw OC most likely exchanged initial MOM. A potential for lignin accumulation in the MOM of soils incubated with straw and redox fluctuation was observed for both soil types. Lignin and carbohydrates suggest a plant origin of MOM formed under redox fluctuation. The initially similar bacterial community composition of the Alisol and Andosol changed differently under redox fluctuation. The stronger change in the Alisol indicates less protective microbial habitats. In summary, the overall turnover of straw OC in soils under redox fluctuation seems to be independent of soil type, while net accumulation of SOC as well as the evolution of the bacterial community structure may in part depend on soil type, suggesting an impact of the soil’s mineral composition.

23408. 题目: Deep soil flipping increases carbon stocks of New Zealand grasslands
文章编号: N19020908
期刊: Global Change Biology
作者: Marcus Schiedung, Craig S Tregurtha, Michael H Beare, Steve M Thomas, Axel Don
更新时间: 2019-02-09
摘要: Sequestration of soil organic carbon (SOC) has been recognised as an opportunity to off‐set global carbon dioxide (CO₂) emissions. Flipping (full inversion to 1‐3 m) is a practice used on New Zealand's South Island West Coast to eliminate water‐logging in highly podzolized sandy soils. Flipping results in burial of SOC formed in surface soil horizons into the subsoil and the transfer of subsoil material low in SOC to the “new” topsoil. The aims of this study were to quantify changes in the storage and stability of SOC over a 20 year period following flipping of high productive pasture grassland. Topsoils (0‐30 cm) from sites representing a chronosequence of flipping (3‐20 years old) were sampled (2005/07) and re‐sampled (2017) to assess changes in topsoil carbon stocks. Deeper samples (30‐150 cm) were also collected (2017) to evaluate changes in stocks of SOC previously buried by flipping. Density fractionation was used to determine SOC stability in recent and buried topsoils. Total SOC stocks (0‐150 cm) increased significantly by 69 ± 15 % (179 ± 40 Mg SOC ha⁻¹) over 20 years following flipping. Topsoil burial caused a one‐time sequestration of 160 ± 14 Mg SOC ha⁻¹ (30‐150 cm). The top 0‐30 cm accumulated 3.6 Mg SOC ha⁻¹ year⁻¹. The chronosequence and re‐sampling revealed SOC accumulation rates of 1.2‐1.8 Mg SOC ha⁻¹ year⁻¹ in the new surface soil (0‐15 cm) and a SOC deficit of 36 ± 5 % after 20 years. Flipped subsoils contained up to 32 % labile SOC (compared to <1 % in un‐flipped subsoils) thus buried SOC was preserved. This study confirms that burial of SOC and the exposure of SOC depleted subsoil results in an overall increase of SOC stocks of the whole soil profile and long‐term SOC preservation.

23409. 题目: Comparison of different sequential extraction procedures for mercury fractionation in polluted soils
文章编号: N19020907
期刊: Environmental Science and Pollution Research
作者: Haochen Dong, Liu Feng, Yu Qin, Muxinjian Luo
更新时间: 2019-02-09
摘要: Three sequential extraction procedures (SEPs), modified Tessier, modified BCR, and CIEMAT, were compared for mercury fractionation in polluted soils. With satisfactory total mercury recovery, the modified Tessier and modified BCR SEPs were comparable with each other in terms of extraction efficiency in equivalent mercury fractions, whereas both SEPs were not as efficient as the CIEMAT SEP. However, the CIEMAT SEP might underestimate the oxidizable mercury fractions due to the humic and fulvic complexes instead of the organic matter of the other two SEPs. For mercury bioavailability identification, based on Pearson correlation analysis, all fractions in each SEP were significantly correlated with mercury uptake in Ipomoea aquatica, causing difficulty in comparison. Partial correlation analysis indicated that the mobile mercury fractions extracted by the first step in all three SEPs had a positive correlation with mercury uptake by plant, while mercury bound to organic matter extracted by both modified Tessier and modified BCR SEPs presented negative correlation with mercury uptake by plant which was in contrast to CIEMAT SEP. Meanwhile, clearly positive correlations between mercury fractions extracted by the former three steps of CIEMAT SEP and mercury uptake in Ipomoea aquatica were observed, demonstrating that CIEMAT SEP provided more accurate results related to Hg bioavailability than did the other two SEPs.

23410. 题目: Variation in N₂O emission and N₂O related microbial functional genes in straw- and biochar-amended and non-amended soils
文章编号: N19020906
期刊: Applied Soil Ecology
作者: Rong Huang, Yingyan Wang, Jiang Liu, Jiacheng Li, Guoxin Xu, Mei Luo, Chang Xu, En Ci, Ming Gao
更新时间: 2019-02-09
摘要: Reducing mineral fertilizer application is an important management practice for mitigating nitrous oxide (N₂O) emissions. Crop straw and biochar are two farmer-friendly residues that can be used for reducing the application of mineral fertilizers. However, different effect of straw- and biochar-amended and non-amended soils on N₂O emissions is not well understood. Here, we conducted a mesocosm experiment in a vegetable field in Southwestern China using four treatments: control (CT, no addition), solely mineral fertilizers at the recommended dosage (F), maize straw with mineral fertilizers (SF), and biochar with mineral fertilizers (BF), based on the same total nitrogen, phosphorus and potassium contents. Soil N₂O fluxes, cumulative N₂O emission, soil chemical parameters, the abundance of N₂O related microbial functional genes (amoA, nirS, nirK and nosZ) and microbial community structure were monitored and analyzed. Compared to F, the SF treatment increased the cumulative N₂O emission. However, no significant difference was observed in cumulative N₂O emission between F and BF treatments. Covariation in cumulative N₂O emission and soil dissolved organic nitrogen (DON) content indicated that heterotrophic ammonia oxidation fueled by soil DON might be the driving force for N₂O production. Compared to F, both SF and BF treatments increased the amoA gene copy numbers of ammonia oxidizing bacteria (AOB) but reduced those of ammonia oxidizing archaea (AOA); nirS and nosZ gene copy numbers were also reduced under SF and BF treatments. Compared to SF, the diversity of nirK and nosZ communities under the BF treatment was increased, whereas the diversity of nirS community was decreased. Lower cumulative N₂O emission under BF than that under SF may be attributed to lower N₂O production from heterotrophic ammonia oxidation fueled by soil DON and increased N₂O consumption mediated by nosZ-harboring denitrifiers.

23411. 题目: Contribution of macroalgal wrack consumers to dissolved inorganic nitrogen concentrations in intertidal pore waters of sandy beaches
文章编号: N19020905
期刊: Estuarine, Coastal and Shelf Science
作者: Heili E. Lowman, Kyle A. Emery, Lila Kubler-Dudgeon, Jenifer E. Dugan, John M. Melack
更新时间: 2019-02-09
摘要: Sandy beaches are widespread ecosystems that often sustain food webs with allochthonous subsidies of organic matter. We examined the contribution of intertidal talitrid amphipods, a dominant consumer of macroalgal wrack subsidies on sandy beaches in temperate zones, to the remineralization of wrack and resulting nutrient concentrations in intertidal pore water. The abundance of wrack (as cover) is strongly correlated with that of talitrid populations in multi-year data from quantitative surveys (2013–2018). Ammonium (NH₄⁺) is the dominant form of dissolved inorganic nitrogen at depths ranging from 0 to 160 cm in intertidal pore water collected in 2013, and pore waters are seldom hypoxic (dissolved oxygen < 2 mg L⁻¹). We evaluated the effects of intertidal consumers on nutrient regeneration in laboratory mesocosms. Over the course of replicated 5-day incubations, treatments containing talitrid amphipods, Megalorchestia corniculata, and giant kelp, Macrocystis pyrifera, produced elevated dissolved concentrations of ammonium and nitrate, compared to treatments with only sand, seawater, and kelp. Our measurements suggest talitrid amphipods may elevate ammonium concentrations by 4–198 μM day⁻¹; the ammonium produced may be utilized by beach microbes or exported offshore by tidal flushing. Our study highlights the role of intertidal consumers in maintaining important ecosystem functions, such as organic matter processing and nutrient regeneration.

23412. 题目: Evaluation of orange peel waste and its biochar on greenhouse gas emissions and soil biochemical properties within a loess soil
文章编号: N19020904
期刊: Waste Management
作者: Tanveer Ali Sial, Zhilong Lan, Muhammad Numan Khan, Ying Zhao, Farhana Kumbhar, Jiao Liu, Afeng Zhang, Robert Lee Hill, Altaf Hussain Lahori, Mehurnisa Memon
更新时间: 2019-02-09
摘要: The environmentally safe disposal of the large quantity of orange peels waste produced each day causes economic and environmental problems, which after conversion into biochar via pyrolysis technique might be used as an effective soil amendment. In this study, a 90-day incubation experiment was conducted to investigate the effects of orange peel waste and waste-derived biochar amendments on greenhouse gas emissions (GHG), soil biochemical properties, and soil enzyme activities. There were five treatments with different amendment levels: control without an amendment (Control), orange waste 1% (W1), orange waste 2% (W2), orange waste biochar 1% (B1), and orange waste biochar 2% (B2). The results showed that, compared with control, the amendments decreased cumulative N₂O emissions by 59.2% (B2), 45.2% (B1), 20.6% (W2) and 10.2% (W1), respectively; and increased cumulative CH₄ emissions by 81.7% (W1), 84.4% (W2), 75.8% (B1) and 74.9% (B2), respectively. Cumulative CO₂ emissions decreased for the B1 (29.3%) and B2 (43.5%) over the waste treatments. While soil pH, SOC, nitrate nitrogen (NO₃⁻-N) and enzyme activities (urease and catalase) were significantly increased with the passage of time from the biochar amendments, ammonium nitrogen (NH₄⁺-N) and invertase activities did not show this trend with time. Our study suggests that orange peel waste conversion to biochar should be a viable alternate method of disposal since land application resulted in reduced GHG and improvements in soil fertility.

23413. 题目: Warming reduces the increase in N₂O emission under nitrogen fertilization in a boreal peatland
文章编号: N19020903
期刊: Science of The Total Environment
作者: Yu Gong, Jianghua Wu, Judith Vogt, Thuong Ba Le
更新时间: 2019-02-09
摘要: Peatlands are known as N₂O sinks or low N₂O sources due to nitrogen (N) limitation. However, climate warming and N deposition can modulate this limitation, and little is known about the combinative effects of them on N₂O emission from boreal peatlands. In this study, experimental warming and N fertilization treatments were conducted at a boreal peatland in western Newfoundland, Canada. Contrary to previous studies on permafrost peatland and alpine meadows, the effect of warming treatment on N₂O flux was not detectable during the growing seasons of 2015 and 2016. The N fertilization treatment significantly increased the N₂O flux by 1.61 nmol m⁻² s⁻¹ due to increased N availability. Noticeably, warming reduced the effect of N fertilization treatment on N₂O flux with high significance in the middle growing season of 2015. This can be attributed to low N availability caused by stimulated vegetation growth in the warming treatment. In addition, the results showed that total nitrogen was the main control on N₂O emission under N fertilization, while dissolved organic carbon was the main driver under the combined treatment of warming and N fertilization. Due to elevated N₂O emissions under N deposition/fertilization, the contribution of N₂O to global warming and ozone depletion should not be ignored.
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23414. 题目: A novel method for evaluating the potential release of trace metals associated with rainfall leaching/runoff from urban soils
文章编号: N19020902
期刊: Science of The Total Environment
作者: Bo Gao, Li Gao, Dongyu Xu, Min Zhang, Xiaodong Qu, Yanyan Li
更新时间: 2019-02-09
摘要: The release of pollutants in soils owing to rainfall is a major challenge related to urbanization. Here, urban soils from different functional zones were collected to evaluate the release risk and estimate their annual release amounts of trace metals (Co and Ni) using multiple techniques, including diffusive gradients in thin-films (DGT), DGT-induced fluxes in sediments (DIFS) model, and Fourier-transform infrared (FTIR) spectroscopy. The results indicate that the average concentration of Co (6.55 mg kg⁻¹) was slightly lower than that of the local soil background, whereas for Ni, the trend was reversed. Risk assessments based on total concentrations show that the soil samples were uncontaminated with Co while uncontaminated to moderately contaminated with Ni. However, the mobility coefficients indicate that Co posed low to medium risk, while Ni posed low risk. Hence, further investigation of DGT measurements and DIFS model show that the DGT-measured Co and Ni concentrations were lower than the corresponding concentrations in solution, leading to low R values and the partial resupply of Co and Ni from the solid phase. The FTIR spectra and elemental analysis suggest that because of the electrostatic attraction and complexation of the hydrosilicate minerals and organic matters, the metal resupply was restrained, resulting in them being only a partial resupply. Moreover, the mobility of Co was mainly controlled by the resupply ability, response time, and desorption rate; while for Ni, the particle concentration and porosity played important roles in determining mobility. In addition, the release amounts of the trace metals were quantified using the binary mixing equation. The estimated annual release amounts of Co and Ni in Pingshan District were 0.44–3.54 t and 1.93–16.47 t, respectively. This study provides an effective in-situ method for estimating the release amounts of trace metals in soils during rainfall combining DGT and DIFS model.
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23415. 题目: Spatial and life cycle assessment of bioenergy-driven land-use changes in Ireland
文章编号: N19020901
期刊: Science of The Total Environment
作者: Robbie Clarke, Amanda Sosa, Fionnuala Murphy
更新时间: 2019-02-09
摘要: Bioenergy crops are forecast to play a significant role if Ireland is to reach the 2020 and beyond targets set by the European Union's Renewable Energy Directive (RED). The aim of this study is to evaluate the environmental impacts associated with the cultivation of bioenergy crops in Ireland including land-use change (LUC) emissions by using geographical information systems (GIS) and Life Cycle Assessment (LCA). In this study, GIS is used to identify, and measure LUC changes associated with cultivation of Miscanthus and Short Rotation Coppice (SRC) willow. An LCA study was carried out to estimate the greenhouse gas (GHG) emissions from the LUC caused by the cultivation of bioenergy crops. The results find that miscanthus caused 86% of all LUC with SRC Willow accounting for 14%. The LCA results identify two major processes that contribute to total GHG emissions; field operations and loss of soil organic carbon (SOC) stocks. Land preparation, harvesting and the production of synthetic fertiliser are found to be the most significant contributors to field emissions. SOC emission for the conversion of pasture to SRC willow accounts for a large proportion of the overall GHG emissions. Conversion of arable land to miscanthus and SRC willow both cause a net reduction of GHG emissions. Sensitivity analysis on the type of fertilisers used and the inclusion of indirect land-use changes (iLUC), highlight the impacts that these have on the overall system performance. The replacement of synthetic fertiliser with biogenic fertiliser reduced overall GHG emissions. The inclusion of general iLUC data results in a large increase in total GHG emissions because of displaced food crops that must be grown elsewhere. The study shows that conversion of arable to miscanthus and SRC willow is preferable when cultivating bioenergy crops while conversion of pasture to SRC willow should be avoided.
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23416. 题目: Fire-derived organic matter retains ammonia through covalent bond formation
文章编号: N19020815
期刊: Nature Communications
作者: Rachel Hestrin, Dorisel Torres-Rojas, James J Dynes, James M Hook, Tom Z Regier, Adam W Gillespie, Ronald J Smernik, Johannes Lehmann
更新时间: 2019-02-08
摘要: Fire-derived organic matter, often referred to as pyrogenic organic matter (PyOM), is present in the Earth’s soil, sediment, atmosphere, and water. We investigated interactions of PyOM with ammonia (NH3) gas, which makes up much of the Earth’s reactive nitrogen (N) pool. Here we show that PyOM’s NH3 retention capacity under ambient conditions can exceed 180 mg N g−1 PyOM–carbon, resulting in a material with a higher N content than any unprocessed plant material and most animal manures. As PyOM is weathered, NH3 retention increases sixfold, with more than half of the N retained through chemisorption rather than physisorption. Near-edge X-ray absorption fine structure and nuclear magnetic resonance spectroscopy reveal that a variety of covalent bonds form between NH3-N and PyOM, more than 10% of which contained heterocyclic structures. We estimate that through these mechanisms soil PyOM stocks could retain more than 600-fold annual NH3 emissions from agriculture, exerting an important control on global N cycling.

23417. 题目: The role of benthic macrofauna in the trophic transfer of mercury in a low-diversity temperate coastal ecosystem (Puck Lagoon, southern Baltic Sea)
文章编号: N19020814
期刊: Environmental Monitoring and Assessment
作者: Agnieszka Jędruch, Magdalena Bełdowska, Marcelina Ziółkowska
更新时间: 2019-02-08
摘要: Mercury (Hg) is a global pollutant that affects human and ecosystem health. Hg is a serious threat especially for the marine environment, in which it undergoes bioaccumulation and biomagnification, reaching elevated concentrations in fish and other seafood. The research aimed at investigating the trophodynamics of Hg in the basal links of the marine food chain: benthic macrofauna and its main food sources (i.e. suspended and sediment organic matter, micro- and macrophytobenthos). The results showed that both the amount and the origin of organic matter affected the Hg level in particular trophic groups of macrozoobenthos. The intensive inflow of terrestrial material influenced the enrichment of suspended particles and microphytobenthos in Hg, leading to increased Hg concentrations in filter-feeding macrofauna. The input of Hg-rich marine matter transported from the deeper parts of the Gulf of Gdańsk along with the near-bottom currents caused higher Hg levels in deposit feeders. The biomagnification factor (BMF) of Hg through benthic food web was dependent on environmental conditions occurring in the studied areas, in particular, factors favouring the growth and fecundity of macrofauna. Consequently, as a result of biodilution, the trophic transfer of Hg was less effective in a more productive region, despite the elevated Hg concentrations in dietary components of the macrofauna and in the surrounding environment.

23418. 题目: Reduced mineralization of terrestrial OC in anoxic sediment suggests enhanced burial efficiency in reservoirs compared to other depositional environments
文章编号: N19020813
期刊: Journal of Geophysical Research: Biogeosciences
作者: Anastasija Isidorova, Raquel Mendonça, Sebastian Sobek
更新时间: 2019-02-08
摘要: Freshwater reservoirs are important sites of organic carbon (OC) burial, but the extent to which reservoir OC burial is a new anthropogenic carbon sink is currently unclear. While burial of aquatic OC (by e.g. phytoplankton) in reservoirs may count as a new C sink, the burial of terrestrial OC in reservoirs constitutes a new C sink only if the burial is more efficient in reservoirs than in other depositional environments. We carried out incubation experiments that mimicked the environmental conditions of different depositional environments along the land‐sea continuum (oxic and anoxic freshwater, oxic and anoxic seawater, oxic river bedload, atmosphere‐exposed floodplain) to investigate whether reservoirs bury OC more efficiently compared to other depositional environments. For sediment OC predominantly of terrestrial origin, OC degradation rates were significantly lower, by a factor of 2, at anoxic freshwater and saltwater conditions compared to oxic freshwater and saltwater, river, and floodplain conditions. However, the transformation of predominantly terrestrial OC to methane was one order of magnitude higher in anoxic freshwater than at other conditions. For sediment OC predominantly of aquatic origin, OC degradation rates were uniformly high at all conditions, implying equally low burial efficiency of aquatic OC (76% C loss in 57 days). Since anoxia is more common in reservoirs than in the coastal ocean, these results suggest that reservoirs are a depositional environment in which terrestrial OC is prone to become buried at higher efficiency than in the ocean, but where also the terrestrial OC most efficiently is transformed to methane.

23419. 题目: Investigating adsorption performance of heavy metals onto humic acid from sludge using Fourier-transform infrared combined with two-dimensional correlation spectroscopy
文章编号: N19020812
期刊: Environmental Science and Pollution Research
作者: Yi-jin Yang, Bin Wang, Xu-jing Guo, Chang-wu Zou, Xian-dong Tan
更新时间: 2019-02-08
摘要: Efforts to improve sludge resource utilization have become increasingly important. In this study, humic acid (HA) was extracted from sludge samples collected from a sewage treatment plant, and then used for the adsorption of heavy metals. We used two-dimensional correlation spectroscopy (2D-COS) integrated with Fourier-transform infrared spectroscopy (FTIR) to explore the adsorption between sludge HA (HA) and three metal ions (Cu, Ni, and Pb). The resulting adsorbing data conformed to the isotherm of Langmuir adsorption. The maximum capacity values (q_m) were 5.34, 1.49, and 26.29.8 mg/g for Cu, Ni, and Pb, respectively. The data from 2D-FTIR-COS analysis showed that the susceptibility of the functional group followed the order 2300 → 1130 → 1330 → 1480 → 1580 cm⁻¹ for Cu(II) and Ni(II), and 2300 → 1130 → 1330 → 1480 → 1200 → 1580 cm⁻¹ for Pb(II). The sludge HA with Pb(II) showed more adsorption sites than sludge HA with Cu(II) and Ni(II), and these adsorption sites could preferentially bond with Pb(II) at × 1 compared with Cu(II) and Ni(II). Our findings indicate that 2D-FTIR-COS technology has great potential for application as a useful tool for understanding the adsorption mechanism between adsorbents with heavy metals.

23420. 题目: Experimental investigation and mathematical modeling for microbial removal using potassium permanganate as an oxidant—case study: water treatment plant No. 1, Mashhad, Iran
文章编号: N19020811
期刊: Environmental Monitoring and Assessment
作者: Mohammad Gheibi, Nima Emrani, Mohammad Eftekhari, Mehran Akrami, Javad Abdollahi, Mahmood Ramezani, Alireza Sedghian
更新时间: 2019-02-08
摘要: Preoxidation is an important unit process which can partially remove organic and microbial contaminations. Due to the high concentrations of organic matter entering the water treatment plant, originating from surface water resources, preoxidation by using chlorinated compounds may increase the possibility of trihalomethane (THM) formation. Therefore, in order to reduce the concentration of THMs, different alternatives such as injection of potassium permanganate are utilized. The present study attempts to investigate the efficiency of the microbial removal from raw water entering the water treatment plant No. 1 in Mashhad, Iran, through various doses of potassium permanganate. Then, an examination of the predictive models is done in order to indicate the residual Escherichia coli and total coliform resulted from injecting the potassium permanganate. Finally, the coefficients of the proposed models were optimized using the genetic algorithm. The results of the study show that 0.5 mg L⁻¹ of potassium permanganate would remove 50% of total coliform as well as 80% of Escherichia coli in the studied water treatment plant. Also, assessing the performance of different models in predicting the residual microbial concentration after injection of potassium permanganate suggests the Gaussian model as the one resulting the highest conformity. Moreover, it can be concluded that employing smart models leads to an optimization of the injected potassium permanganate at the levels of 27% and 73.5%, for minimum and maximum states during different seasons of a year, respectively.