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28981. 题目: Improvement of mining soil properties through the use of a new bio-conditioner prototype: a greenhouse trial
文章编号: N18120406
期刊: Journal of Soils and Sediments
作者: Manuel Pantoja-Guerra, Ramiro Ramirez-Pisco, Nelson Valero-Valero
更新时间: 2018-12-04
摘要: Purpose: The effect of a prototype of humic bio-conditioner (H-BC) was assessed on the development of edaphic properties and the growth of maize plants in an edaphic material used as topsoil in the rehabilitation of soils in a coal mine in Colombia. Materials and methods: The trial was carried out in a greenhouse, using pots with edaphic material treated with the addition of doses equivalent to 0 (control), 1, 2, and 4 Mg.ha−1 of H-BC; maize seeds were sown and followed up on for 60 days. Plant growth and soil biological, chemical, and physical variables were registered. Results and discussion: The 4-Mg.ha−1 treatment maintained a significantly higher enzymatic activity than the control on day 60. The respiration of the soil treated with H-BC increased significantly, with the 4-Mg.ha−1 treatment standing out. The 2-Mg.ha−1 treatment induced the most noticeable changes in soil metabolic activity profiles. Increases in root and leaf development were observed in the treatment with 4 Mg.ha−1; apparently, this dose improved the absorption of Ca, K, and S by plants; the physical and soil aggregation indices increased significantly with 4 Mg.ha−1. Conclusions: The results indicate that H-BC can be an alternative as an enhancer of the edaphic material used in soil rehabilitation processes.
28982. 题目: Flocculation-dewatering behavior of waste activated sludge particles under chemical conditioning with inorganic polymer flocculant: Effects of typical sludge properties
文章编号: N18120405
期刊: Chemosphere
作者: Peng Yang, Dandan Li, Weijun Zhang, Ning Wang, Zhaoyi Yang, Dongsheng Wang, Teng Ma
更新时间: 2018-12-04
摘要: The effects of typical sludge properties (solids concentration, soluble extracellular polymeric substances (SEPS) and alkalinity) on waste activated sludge flocculation-dewatering behavior and mechanisms under chemical conditioning with inorganic polymer flocculant-polyaluminum chloride (PACl) were systematically examined in this study. The results indicated that increasing the solids concentration was conductive to sludge dewatering and could greatly decrease the PACl demand in chemical conditioning. Solids concentration had important effects on properties of sludge floc flocculated with PACl, floc structure was more compact and of low EPS concentration at high solids concentrations. High levels of SEPS were adverse to sludge dewaterability after flocculation with PACl, since the SEPS could interact with hydroxy-aluminium through complexation and increase the demand of coagulants. In addition, advantageous speciations of hydroxy-aluminium were rapidly converted into amorphous hydroxides with low flocculation activity at high alkalinity, so the sludge conditioning efficiency was greatly declined. At the same time, the dominant mechanism of chemical conditioning was changed from charge neutralization to sweep coagulation. Finally, this study provides control strategies at complex sludge properties for improving the effectiveness of PACl as a chemical conditioner.
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28983. 题目: Influence of biochar on physico-chemical and microbial community during swine manure composting process
文章编号: N18120404
期刊: Journal of Environmental Management
作者: Balasubramani Ravindran, Dinh Duc Nguyen, Dhiraj Kumar Chaudhary, Soon Woong Chang, Jaisoo Kim, Sang Ryong Lee, JoungDu Shin, Byong-Hun Jeon, SeokJoo Chung, JaeJoung Lee
更新时间: 2018-12-04
摘要: Excessive nutrients and toxic gas emissions from animal manure management are of great global concern, with negative environmental and economic consequences worldwide. Due to biochar recalcitrance and sorption properties, this study investigated the effect of the biochar(BC) derived from bamboo, amendment on swine manure(SM) composting efficiency through physical, physio-chemical, gaseous emissions, microbiological, and phytotoxic analysis during the 56 day process of in-vessel composting. The treatments were set-up from different ratios of biochar to swine manure mixed with sawdust(SD)(i.e. SM + SD + 3%BC(T1), SM:SD + 5 %BC(T2) and SM:SD + 10 %BC (T3)), while treatment without biochar amendment was used as a control, SM:SD(C). The results showed that, compared to the control, biochar amended compost mixtures had significantly reduced (p ≤ 0.05) bulk density, organic matter(OM), C:N ratio, NH3 emission, pathogenic microorganisms, and phytotoxicity effect (Cress seed, Lepidium sativum Linn.). On the other hand, biochar amendment mixtures had increased total porosity, water holding capacity, rapid thermophilic temperature, and nitrate nitrogen. However, with the most prominent effects in terms of the nutrient quality and degradation rate of compost mixtures, the amendment of 10% biochar is recommended for swine manure management through the composting process.
28984. 题目: Southern Ocean controls of the vertical marine δ13C gradient – a modelling study
文章编号: N18120403
期刊: Biogeosciences
作者: Anne L. Morée, Jörg Schwinger, and Christoph Heinze
更新时间: 2018-12-04
摘要: δ13C, the standardised 13C∕12C ratio expressed in per mille, is a widely used ocean tracer to study changes in ocean circulation, water mass ventilation, atmospheric pCO2, and the biological carbon pump on timescales ranging from decades to tens of millions of years. δ13C data derived from ocean sediment core analysis provide information on δ13C of dissolved inorganic carbon and the vertical δ13C gradient (i.e. Δδ13C) in past oceans. In order to correctly interpret δ13C and Δδ13C variations, a good understanding is needed of the influence from ocean circulation, air–sea gas exchange and biological productivity on these variations. The Southern Ocean is a key region for these processes, and we show here that Δδ13C in all ocean basins is sensitive to changes in the biogeochemical state of the Southern Ocean. We conduct a set of idealised sensitivity experiments with the ocean biogeochemistry general circulation model HAMOCC2s to explore the effect of biogeochemical state changes of the Southern and Global Ocean on atmospheric δ13C, pCO2, and marine δ13C and Δδ13C. The experiments cover changes in air–sea gas exchange rates, particulate organic carbon sinking rates, sea ice cover, and nutrient uptake efficiency in an unchanged ocean circulation field. Our experiments show that global mean Δδ13C varies by up to about ±0.35‰ around the pre-industrial model reference (1.2‰) in response to biogeochemical change. The amplitude of this sensitivity can be larger at smaller scales, as seen from a maximum sensitivity of about −0.6‰ on ocean basin scale. The ocean's oldest water (North Pacific) responds most to biological changes, the young deep water (North Atlantic) responds strongly to air–sea gas exchange changes, and the vertically well-mixed water (SO) has a low or even reversed Δδ13C sensitivity compared to the other basins. This local Δδ13C sensitivity depends on the local thermodynamic disequilibrium and the Δδ13C sensitivity to local POC export production changes. The direction of both glacial (intensification of Δδ13C) and interglacial (weakening of Δδ13C) Δδ13C change matches the direction of the sensitivity of biogeochemical processes associated with these periods. This supports the idea that biogeochemistry likely explains part of the reconstructed variations in Δδ13C, in addition to changes in ocean circulation.
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28985. 题目: Small microbialites from the basal Triassic mudstone (Tieshikou, Jiangxi, South China): Geobiologic features, biogenicity, and paleoenvironmental implications
文章编号: N18120402
期刊: Palaeogeography, Palaeoclimatology, Palaeoecology
作者: Hao Yang, Zhong-Qiang Chen, Stephen Kershaw, Wei Liao, Enlü Lü, Yuangen Huang
更新时间: 2018-12-04
摘要: We report small microbialites from the calcareous mudstone slightly above the Permian–Triassic boundary (PTB) in the Tieshikou section, southern Jiangxi Province, South China. The newly found microbialite is a bowl-like structure, which contrasts with the surrounding calcareous mudstone. The small microbialite is composed of columnar forms and fan-shaped structures. Mini-columnar structures resemble mini stromatolites. In plane view, most branches are patchy or strip-shaped, with clotted structures, resembling that of a thrombolite. Fan-shaped cement precipitates are comprised of multiple crystal fans that have a radiating texture and that show distinct growth laminae. The radiating fabrics are represented by rod-shaped filaments under SEM, which are interpreted as calcified trichomes/filaments. Prominent micropores occur within the rods, and they may be the plane views of multiple sheaths of the false branching zone of trichomes. Thus, both the columnar forms and radiating fans are probably microbial in origin. Moreover, three types of nano-sized structures: intraparticle micropores, fibrous biofilms, and filamentous sheaths are also pronounced in both the columnar structures and cement fans of the Tieshikou microbialite, all suggestive of biogenicity. These well-preserved fibrous biofilms probably represent calcified extracellular polymeric substances (EPS), and linear sheaths are interpreted as the traces of bacterial activities during the precipitation of dolomite crystals. The Tieshikou microbialite therefore shares similar biogenetic mechanisms with other PTB microbialites. The combination of the absence of pyrite framboids, slightly negative carbon isotope values, and an association with abundant ammonoids, bivalves, and gastropods indicates oxic conditions during the growth of the Tieshikou microbialite. Moreover, the nodular preservational state resembles widely distributed nodular mudstones or muddy limestones of the Lower Triassic successions worldwide. This implies that nodular mudstone or argillaceous limestones may also have been deposited in microbe-rich environments, in which terrigenous supply was abundant.
28986. 题目: Biogeochemical controls on black shale deposition during the Frasnian-Famennian biotic crisis in the Illinois and Appalachian Basins, USA, inferred from stable isotopes of nitrogen and carbon
文章编号: N18120401
期刊: Palaeogeography, Palaeoclimatology, Palaeoecology
作者: Benjamin T. Uveges, Christopher K. Junium, Diana L. Boyer, Phoebe A. Cohen, James E. Day
更新时间: 2018-12-04
摘要: The Frasnian-Famennian biotic crisis is marked by two distinct intervals known as the Lower and Upper Kellwasser Events (KWEs) that in many locations are associated with deposition of organic-rich shales. Sedimentary nitrogen and carbon isotopes offer insight into the biogeochemical processing of nutrients, production of organic matter, and palaeoceanographic conditions during the KWEs. Here we present new bulk nitrogen (δ15Nbulk) and organic carbon (δ13Corg) isotope data from the Late Devonian Appalachian and Illinois Basins (AB and IB), with a focus on intervals encompassing the KWEs. Black shales from the IB and AB, including the KWEs, are 15N-depleted (−1.0–+2.0‰) and have significantly lower δ15Nbulk than interbedded grey shales (+0.5–+4.0‰), a trend consistent with many instances of black shale deposition in the Phanerozoic. Organic carbon isotopes exhibit the broad, positive excursions (~+3.5‰ from background) that are typical of the KWEs globally. Superimposed over these positive excursions in δ13Corg are sharp decreases of up to ~3.0‰ within the black shale beds, to as low as −30.5‰. The pattern of δ15Nbulk and δ13Corg values suggests that the depth of the chemocline and the degree of water-column stratification exert a primary control on both δ15Nbulk and δ13Corg during black shale deposition. In the context of the Frasnian-Famennian biotic crisis, the oscillating redox state and changing temperatures would have likely placed extreme stress on organisms within the marine environment of the AB and IB and may potentially have been a contributing factor to diversity loss over this time period.
28987. 题目: Short-term impacts of high levels of nitrogen fertilization on soil carbon dynamics in a tropical pasture
文章编号: N18120305
期刊: CATENA
作者: Bernardo Melo Montes Nogueira Borges, Ricardo de Oliveira Bordonal, Maria Lucia Silveira, Edson Luiz Mendes Coutinho
更新时间: 2018-12-03
摘要: Bermudagrass (Cynodon spp.) is widely recognized by its ability to respond positively to nitrogen (N) fertilization. Nitrogen often promotes shoot and root growth and, consequently, increase carbon (C) inputs into the soil via above- and below-ground biomass. The objective of this 2-yr field study was to assess the short-term effects of increased N levels on soil C dynamics of a Tifton 85 bermudagrass pasture grown in a tropical soil. Treatments consisted of five levels of N fertilization (0, 60, 120, 180 and 240 kg ha−1 N) applied at each harvest for a total of four harvest events per year. Soil samples were collected at the 0 to 0.1 and 0.1 to 0.2 m depths for determination of soil C content. The latter was also fractionated into free-light (FLF), particulate organic carbon (POC), and mineral-associated organic carbon (C-min) fractions. Results indicated that N levels showed no effect on total C content and distribution among the various size-density fractions. The top layer (0–0.1 m) was more sensitive to changes in soil C for more recalcitrant fractions (POC and C-min) relative to 0.1–0.2 m layer. Our findings suggest that acceleration of the decomposition rate induced by N fertilization may have offset the potential accumulation of soil C associated with high inputs of above- and below-ground biomass, but additional research is warranted to better elucidate long-term impacts of nitrogen fertilization on soil C dynamics in grassland of tropical regions.
28988. 题目: Alleviation of aluminum phytotoxicity by canola straw biochars varied with their cultivating soils through an investigation of wheat seedling root elongation
文章编号: N18120304
期刊: Chemosphere
作者: Ying Dong, Hui Wang, E Chang, Zhenjie Zhao, Ruhai Wang, Renkou Xu, Jun Jiang
更新时间: 2018-12-03
摘要: The types and amounts of cations and their uptake by plants vary with cultivating soils, which correlates with the carbonates and subsequent alkalis contents in the derived biochars. However, regional differences in the alkaline properties of crop straw biochars are unclear. In the present study, biochars pyrolyzed from canola straws collected from four different regions were used to assess the differences in the alkaline properties among them. The biochars were referred to as YTBC, XCBC, NJBC, and HYBC, respectively, and their feedstocks were collected from four different regions from south to north of China. The NH4OAC exchangeable base cations (K+, Na+, Ca2+, Mg2+) in the biochars were 270.74, 1427.05, 2089.23, and 1516.48 mmol kg−1 for YTBC, XCBC, NJBC, and HYBC, respectively, which were roughly consistent with the exchangeable base cations in the corresponding planting soils (17.57, 28.20, 151.26 and 444.65 mmol kg−1, respectively). The pH, carbonates content, and alkalinity of biochars considerably increased as follows: YTBC < XCBC < NJBC < HYBC. Wheat seedling root elongation experiment indicated that the Al(III) phytotoxicity alleviation effect of the biochars was as follows: HYBC > NJBC > XCBC > YTBC, which was corroborated by the subsequent findings of Evans blue staining, the remnant aluminum (Al(III)) in the reaction solution and Al(III) distribution in the wheat seedling roots. Thus, planting soil had a dominant influence in alleviating Al(III) phytotoxicity, and studies on crop straw biochar properties concerning alkalinities or liming potentials should not only consider crop genera and pyrolysis conditions, but also cultivating conditions.
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28989. 题目: Quantifying hydrophobicity of natural organic matter using partition coefficients in aqueous two-phase systems
文章编号: N18120303
期刊: Chemosphere
作者: Heyun Fu, Kun Liu, Pedro J.J. Alvarez, Daqiang Yin, Xiaolei Qu, Dongqiang Zhu
更新时间: 2018-12-03
摘要: The hydrophobicity of natural organic matter (NOM) is of great significance for its interfacial processes in natural and engineered systems. However, there is no well-accepted method for the routine determination of NOM hydrophobicity. In this study, the hydrophobicity of NOM spanning a wide range of origins and properties was quantified based on their partition coefficients (KATPS) in poly (ethylene glycol)/potassium citrate aqueous two-phase systems (ATPS). The LnKATPS of NOM correlated well with the elemental, structural, and thermodynamic indices commonly used to characterize NOM hydrophobicity, including (O + N)/C, O/C, aromatic and aliphatic carbon, and the free energy of interactions between molecules (ΔGiwi). A simple linear model was developed to predict NOM hydrophobicity using KATPS. The model was validated using 20 natural water samples collected from rivers and lakes, which suggested good prediction power. ATPS scale system is simple, fast, low-cost, environmentally friendly, and requires little pretreatment and small sample volume. Overall, KATPS can be used as quantitative measure of NOM hydrophobicity that facilitates routinely characterizing the interfacial properties of NOM.
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28990. 题目: Total Hg and methylmercury dynamics in a river-floodplain system in the Western Amazon: Influence of seasonality, organic matter and physical and chemical parameters
文章编号: N18120302
期刊: Science of The Total Environment
作者: Inacio A. Pestana, Marcelo G. Almeida, Wanderley R. Bastos, Cristina M.M. Souza
更新时间: 2018-12-03
摘要: Total mercury (Hg) and methylmercury (MeHg) circulation in a connected river-floodplain system composed of two black water (a small forest river, igarapé, and Cuniã Lake) and a white water body (Madeira River), located in the Madeira River Basin were evaluated during the rising-water, early and late falling-water periods. We assessed organic matter (C and N composition, (C:N)a; and δ13C isotopic signature), and physical and chemical influences (pH, dissolved O2, electric conductivity) in relationship to Hg and MeHg concentrations. Hg and MeHg concentrations in a sediment profile and three aquatic macrophytes (E. crassipes, E. azuera and Oryza sp.) were measured. Igarapé and Cuniã Lake showed higher Hg and MeHg concentrations (115–709; 10–25 ng g−1) in the suspended particulate matter compared (SPM) compared to the Madeira River (Hg: 5–16; MeHg: 0.2–0.3 ng g−1), partially independent of seasonality (p = 0.06). Total Hg had higher affinity for the SPM (1.75 times) than for dissolved organic matter. Organic matter characteristics correlated with MeHg concentrations (δ13C and (C:N)a; r2 = 0.79; p < 0.0001), as well as physical and chemical parameters of the water column (dissolved O2 and pH; r2 = 0.80; p < 0.0001), demonstrating that physical and chemical changes between the river-floodplain system affect MeHg circulation and production. The inverse correlation of MeHg and SO42− concentrations (r2 = 0.73; p < 0.0001) suggests the action of sulfate-reducing bacteria. Total Hg and MeHg concentrations as well as %MeHg were detected in the sediment profile (Hg: 24–51; MeHg: 0.6–3.2 ng g−1; %MeHg: 1.8–6.2) and aquatic macrophytes (Hg: 1–30; MeHg: 0.3–7.5 ng g−1; %MeHg: 1.6–33.7). We conclude that the highest Hg and MeHg concentrations in Cuniã Lake, compared to the Madeira River, are due to the physical and chemical differences between these environments.
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28991. 题目: Experimental assessment of occurrences and stability of lead-bearing minerals in bacterial biofilms
文章编号: N18120301
期刊: Chemical Geology
作者: Thaïs Couasnon, Alexandre Gélabert, Georges Ona-Nguema, Sandrine Zanna, Bénédicte Ménez, François Guyot
更新时间: 2018-12-03
摘要: Bio-induced precipitation of lead-bearing minerals is investigated in bacterial biofilms grown by Shewanella oneidensis MR-1 under aerobic conditions. Under the different conditions investigated, thermodynamic calculations establish that the stable mineral phases expected to precipitate are either wulfenite PbMoO4 or cerussite PbCO3. However, observations by electron microscopy show that the first solids precipitated within hours at the experimental solution/biofilm interface are crystals of about 20 nm in diameter of pyromorphite Pb5(PO4)3(OH,Cl). In Mo-bearing systems, the precipitation of the thermodynamically-predicted wulfenite phase is delayed compared to the abiotic experiment and is observed only after 7 days of lead exposure. The initial lead phosphate crystals observed on the extracellular polymeric substances are assumed to result from concurrent local abundances of adsorbed Pb2+ ions and phosphate groups released by metabolically active cells. Scanning electron microscopy observations of samples milled by focused ion beam reveal effective diffusion-limited precipitation of pyromorphite within the well-preserved biofilm porosity.
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28992. 题目: Easily mineralizable carbon in manure-based biochar added to a soil influences N 2 O emissions and microbial-N cycling genes
文章编号: N18120209
期刊: Land Degradation & Development
作者: Zhongmin Dai, Yong Li, Xiaojie Zhang, Jianjun Wu, Yu Luo, Yakov Kuzyakov, Philip C. Brookes, Jianming Xu
更新时间: 2018-12-02
摘要: Manure‐based biochar is an effective amendment to increase both carbon sequestration and the fertility of degraded soils, while the responses of N2O emissions and microbial‐N cycling genes to its application and the underlying mechanisms are poorly understood. Here, four biochars were produced under two pyrolysis temperatures (300 and 700 °C) and with two organic C extraction procedures (water and acetone extraction). The resulting biochars were either with relative enrichment or depletion in easily mineralizable carbon (EMC) compared to recalcitrant C. We added biochars, with urea and sodium nitrate, to a degraded red soil and incubated the amended soils at moisture levels of 60% and 130% field capacity. All the biochars decreased nitrification gene abundance, i.e. amoA. Biochars with EMC had greater stimulatory effects on the abundance of denitrification genes (nirK, nirS and nosZ) and N2O emission, regardless of moisture level and N form, compared with biochar without EMC. Biochar‐induced microbial activity, biochar aliphatics and alkyl groups correlated positively with N2O emission and denitrification gene abundance. The water dissolved organic C of biochar facilitated the conversion of N2O to N2, whereas the acetone extractable C fraction postponed the completion of denitrification. In conclusion, the N2O emission and denitrification gene abundance increased with decreasing biochar aromaticity and increasing EMC content. Our study emphasizes that the EMC supply in manure‐based biochars also importantly mediates soil N2O emission and microbial N cycling genes, adding to current understanding of influencing factors such as biochar pH, porosity, N availability and redox property.
28993. 题目: Human activities in a tropical Mexican desert: impact of rainfed agriculture and firewood extraction on vegetation and soil
文章编号: N18120208
期刊: Land Degradation & Development
作者: Jessica Sosa-Quintero, Héctor Godínez-Alvarez
更新时间: 2018-12-02
摘要: The impacts of human activities on temperate deserts have been evaluated worldwide. However, data about tropical deserts are scarce. In this study, we evaluated the impacts of rainfed agriculture and firewood extraction on vegetation and soil of abandoned croplands (mesquite cropland and goldeneye cropland) and mesquite shrublands (open‐canopy mesquite and closed‐canopy mesquite) in a tropical Mexican desert. We interviewed peasants to understand their management practices and evaluated vegetation traits and soil properties of sites. We also examined the impacts of land management on vegetation and soil with structural equation modeling. Rainfed agriculture consisted of cultivating crops, fertilizing with manure, and introducing goats to croplands after harvest. Goldeneye cropland had higher canopy cover, vegetation structure, and litter cover than mesquite cropland. However, soil in both croplands was highly compacted with low infiltration rate, organic matter, and nutrient content. Firewood extraction only consisted of removing mesquite branches. Open‐canopy mesquite had lower canopy and litter cover, and higher biological soil crust cover than closed‐canopy mesquite. The soil in both shrublands was less compacted with relatively high infiltration rate, organic matter, and nutrient content. Rainfed agriculture decreased soil nutrient content due to removal of native vegetation, plowing, and goat introduction to croplands. In contrast, firewood extraction maintained a relatively high soil nutrient content because branch removal enables the establishment of biological soil crusts, which increased the infiltration rate and nutrient availability. Thus, firewood extraction has a lower impact on the structure and function of fluvial terraces than rainfed agriculture in this tropical desert.
28994. 题目: Postdepositional aerobic and anaerobic particulate organic matter degradation succession reflected by dinoflagellate cysts: The Madeira Abyssal Plain revisited
文章编号: N18120207
期刊: Marine Geology
作者: Karin A.f. Zonneveld, Daniel D. Gray, Gerhard Kuhn, Gerard J.m. Versteegh
更新时间: 2018-12-02
摘要: We report on the succession of selective degradation of dinoflagellate cyst species that can be considered representative for discrete particulate organic matter (POM) classes of different degradability. The effects of anaerobic and aerobic degradation as well as bioturbation in a natural setting are documented in high resolution by means of palynological and geochemical analyses on Madeira Abyssal Plain A- and F-turbidites. These turbidites are unique as their initial ungraded sediments are affected by a downward penetrating oxydation front. Geochemical analyses document the presence of an active downward penetrating oxidation front in the A turbidite, and a palaeo-oxidation front in the F-turbidite. In this latter turbidite, several zones can be distinguished from top to bottom: an oxidised bioturbated zone, an oxidised but not-bioturbated zone, a visible paleo-oxidation front, and a narrow nitrogenous zone overlying unoxidised sediments. We are the first to report that anaerobic degradation within the nitrogenous zones in both turbidites affects cysts of some heterotrophic dinoflagellates. The cyst species affected (Echinidinium aculeatum, Echinidinium spp., cysts of Protoperidinium monospinum and Brigantedinium spp.) exponentially decrease in this zone that is further characterised by a strong decrease in sulphur content due to sulphide oxidation. Degradation rates are different for each species. These cysts of heterotrophic dinoflagellates consist of a nitrogen-rich glycan in contrast to the cellulosic cysts walls of phototrophic dinoflagellates. Therefore, our observation supports the hypothesis that the quality of organic matter plays an important role in OM degradation in oxygen deficient environments with N-rich OM being more labile than other components in these environments. All heterotrophic species are strongly affected by aerobic degradation with their cyst concentrations exponentially decreasing with increasing oxygen exposure. Degradation rates vary between species and range von highly degradable to slightly degradable. Most strongly affected are cysts of Protoperidinium monospinum, Brigantedinium spp., and Echinidinium spp. Increasingly less affected are: Selenopemphix nephroides, Selenopemphix quanta, other Peridinioids and Echinidinium aculeatum. An effect of aerobic degradation on photosynthetic species could only be observed for Pentapharsodinium dalei. All Impagidinium species appeared to be resistant to aerobic degradation. Despite having analysed only a limited number of samples in the bioturbated zone of the F-turbidite, we have strong indications that the bioturbation can lead to the degradation of POM that is not affected by aerobic degradation alone. The cyst species Spiniferites ramosus, Impagidinium paradoxum, Lingulodinium machaerophorum, Nematosphaeropsis labyrinthus, Spiniferites spp., Impagidinium sphaericum, Spiniferites elongates and Spiniferites mirabilis do not show concentration changes in the non-bioturbated aerobic sediments but their concentrations are considerably decreased in the bioturbated part of the F-turbidite. This supports the hypothesis that bioturbation can increase the degradation of POM by e.g. increasing oxygen exposure time and/or by an alteration of aerobic and anaerobic conditions. We furthermore show that the degradation rates of POM components represented by individual cyst species differ between zones with different redox and biological conditions. This implies that POM degradation reaction rate coefficients are environment dependent. Our observation that dinoflagellate cyst species have different degradation rates ranging from extremely labile to extremely recalcitrant within the individual redox/bioturbation zones supports the hypothesis that cyst walls have a species specific molecular structure. Our results support continuum models of organic matter degradation that assume a continuous distribution of organic matter reactivity.
28995. 题目: Physical-chemical interactions between pharmaceuticals and biochar in synthetic and real urine
文章编号: N18120206
期刊: Chemosphere
作者: Avni Solanki, Treavor H. Boyer
更新时间: 2018-12-02
摘要: This research advances the knowledge of the pharmaceutical removal interactions by biochar in synthetic and real urine through the use of reference adsorbents and adsorbate probes. Earlier work has combined biochar and urine for pharmaceutical removal, however, the interactions that influence adsorption are unknown. In this study, bamboo biochar and softwood biochar were chosen as the representative materials and the model pharmaceuticals were naproxen and paracetamol. To further investigate the physical-chemical interactions, two nonpolar adsorbates, para-xylene and dimethylnaphthalene, were tested. Graphite and anion exchange resin, were used to isolate van der Waals and electrostatic interactions, respectively. Experimental kinetic and equilibrium data were fit to multiple adsorption models where the pseudo-second order and Freundlich exhibited the best fit, respectively. The Freundlich and Langmuir parameters had similar trends showing that softwood had the highest adsorption capacity. The model parameters indicated higher selectivity for nonpolar para-xylene and dimethylnaphthalene by graphite and polar paracetamol and naproxen by softwood biochar. The decreasing trend of importance of key interactions for pharmaceutical sorption to biochar are: van der Waals > hydrogen bonding > electrostatic interactions. No statistically significant difference was found between urine age (fresh vs. hydrolyzed) and pharmaceutical removal; however, the urine matrix (synthetic vs. synthetic with metabolites vs. real urine) did show a statistically significant difference on pharmaceutical removal where synthetic urine had comparatively greater adsorption. As constituents (i.e., metabolites) were added to urine matrices, reduced adsorption of pharmaceuticals was observed, indicating that adsorption processes should be tested in real urine for accuracy.
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28996. 题目: Synthesis of MgO-coated corncob biochar and its application in lead stabilization in a soil washing residue
文章编号: N18120205
期刊: Environment International
作者: Zhengtao Shen, Jingzhuo Zhang, Deyi Hou, Daniel C.W. Tsang, Yong Sik Ok, Daniel S. Alessi
更新时间: 2018-12-02
摘要: In this study, a magnesium oxide (MgO) coated corncob biochar (MCB) was synthesized by pyrolyzing MgCl2 pretreated corncob, for a better performance in lead immobilization in a contaminated soil compared with corncob biochar (CB). The properties and microstructures of CB and MCB were investigated. It was observed that MgO particles ranging from 1 to 2 μm were well coated on MCB, and the MgO content in MCB was calculated at 29.90% in w/w. The surface area of the biochar was significantly enhanced from 0.07 to 26.56 m2/g after the MgO coating. The MgO coating also significantly facilitated the lead removal percentage from 23% to 74% in aqueous solution by biochar. CB failed to immobilize lead in a soil washing residue and could not reduce its environmental risks in a laboratory incubation study. In contrast, MCB was applied to the soil and resulted in a significant reduction in TCLP leached lead from 10.63 to 5.24 mg/L (reduced by 50.71%). The comparison between MCB and other amendments suggests that the biochar component of MCB adsorbed lead onto its surface through cation-π interaction and increased surface adsorption due to higher surface area, and then the MgO coated on MCB's surface further enhanced the adsorption through precipitation. The synergistic roles of biochar-mineral composites make them a promising candidate for soil remediation.
28997. 题目: Regulation, formation, exposure, and treatment of disinfection by-products (DBPs) in swimming pool waters: A critical review
文章编号: N18120204
期刊: Environment International
作者: Linyan Yang, Xueming Chen, Qianhong She, Guomin Cao, Yongdi Liu, Victor W.-C. Chang, Chuyang Y. Tang
更新时间: 2018-12-02
摘要: The microbial safety of swimming pool waters (SPWs) becomes increasingly important with the popularity of swimming activities. Disinfection aiming at killing microbes in SPWs produces disinfection by-products (DBPs), which has attracted considerable public attentions due to their high frequency of occurrence, considerable concentrations and potent toxicity. We reviewed the latest research progress within the last four decades on the regulation, formation, exposure, and treatment of DBPs in the context of SPWs. This paper specifically discussed DBP regulations in different regions, formation mechanisms related with disinfectants, precursors and other various conditions, human exposure assessment reflected by biomarkers or epidemiological evidence, and the control and treatment of DBPs. Compared to drinking water with natural organic matter as the main organic precursor of DBPs, the additional human inputs (i.e., body fluids and personal care products) to SPWs make the water matrix more complicated and lead to the formation of more types and greater concentrations of DBPs. Dermal absorption and inhalation are two main exposure pathways for trihalomethanes while ingestion for haloacetic acids, reflected by DBP occurrence in human matrices including exhaled air, urine, blood, and plasma. Studies show that membrane filtration, advanced oxidation processes, biodegradation, thermal degradation, chemical reduction, and some hybrid processes are the potential DBP treatment technologies. The removal efficiency, possible mechanisms and future challenges of these DBP treatment methods are summarized in this review, which may facilitate their full-scale applications and provide potential directions for further research extension.
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28998. 题目: Exposure to polycyclic aromatic hydrocarbons in women living in the Chinese cities of BaoDing and Dalian revealed by hair analysis
文章编号: N18120203
期刊: Environment International
作者: Paul Palazzi, Sakina Mezzache, Nasrine Bourokba, Emilie M. Hardy, Anna Schritz, Philippe Bastien, Claude Emond, Jing Li, Jeremie Soeur, Brice M.R. Appenzeller
更新时间: 2018-12-02
摘要: Polycyclic aromatic hydrocarbons (PAH) are produced from incomplete combustion of organic matter and released as environmental contaminants from activities such as transports, wood combustion, coal-fired power plants. In numerous urban areas worldwide, the levels of PAH exposure are considered critical regarding public health issues. The possibility to detect PAH and PAH metabolites biologically incorporated in human hair was demonstrated and proposed as biomarkers of exposure. Nevertheless, the possibility to distinguish different levels of exposure between different populations is still needed to validate the relevance of hair analysis in epidemiological studies. In this work, hair samples were collected from 204 women from two cities in China based on one year Air Quality Index history from governmental data (Baoding as polluted city and Dalian less polluted city). 8 out of the 15 parent PAH and 7 out of the 56 metabolites analyzed in this study were detected in all the samples. The highest concentrations in hair were observed for phenanthrene (4.2 to 889 pg/mg) > fluoranthene (1.05 to 204 pg/mg) > pyrene (3.2 to 124 pg/mg) for parent PAH, and for 9-OH-fluorene (0.04 to 1.78 pg/mg) > 2-OH-naphthalene (0.68 to 811 pg/mg) > 1-OH-anthracene (0.24 to 10.9 pg/mg) for metabolites. 14 parent PAH and 15 metabolites presented a significantly higher concentration in the hair samples collected from Baoding, as compared to Dalian. The median concentration of parent PAH was from 1.5 to 2.8 times higher in the hair of the subjects from Baoding than in subjects from Dalian and that of PAH metabolites was from 1 to 2.3 times higher. The study of inter-chemical associations revealed similarities and differences between the two areas, suggesting common and different sources of exposure depending on PAH respectively. The results confirmed the relevance of hair analysis to identify qualitative and quantitative differences in PAH exposure between populations from different areas. This study is the first one to investigate both parent PAH and their metabolites in a biological matrix.
28999. 题目: Phosphatized early Cambrian archaeocyaths and small shelly fossils (SSFs) of southwestern Mongolia
文章编号: N18120202
期刊: Palaeogeography, Palaeoclimatology, Palaeoecology
作者: Sara B. Pruss, Camille H. Dwyer, Emily F. Smith, Francis A. Macdonald, Nicholas J. Tosca
更新时间: 2018-12-02
摘要: Archaeocyaths are an enigmatic group of calcifying sponges prevalent in early Cambrian (Terreneuvian to Series 2) successions around the world and preserved predominantly in reefal buildups, but also in adjacent reworked deposits. Here we report exceptionally preserved phosphatized archaeocyaths and small shelly fossils from phosphatized reef flank deposits at the top of the Salaagol Formation of southwestern Mongolia. Recent chemostratigraphic age models suggest that these archaeocyaths are among the earliest reported in the Terreneuvian Stage 2 (Tommotian). These fossils provide a window into the mechanisms of archaeocyath phosphatization, a generally rare mode of archaeocyath preservation. To assess the composition and nature of phosphatization, fossil assemblages were examined in insoluble residue and thin section. These archaeocyaths are preserved as phosphatic internal molds in residue, and both phosphatized and unphosphatized archaeocyaths are present in thin section. The occurrence of internal molds and complementary mineralogical data suggest that the decay of organic material within the archaeocyaths created the necessary redox conditions for apatite nucleation. We propose that, shortly after death, this assemblage was transported to a deeper water environment, and that the presence of organic matter in a low oxygen setting led to abundant phosphatization of archaeocyaths.
29000. 题目: Nanoparticle stability in lake water shaped by natural organic matter properties and presence of particulate matter
文章编号: N18120201
期刊: Science of The Total Environment
作者: Danielle L. Slomberg, Patrick Ollivier, Hélène Miche, Bernard Angeletti, Auguste Bruchet, Marc Philibert, Jonathan Brant, Jérôme Labille
更新时间: 2018-12-02
摘要: Predicting nanoparticle (NP) fate in the environment continues to remain a challenge, especially for natural surface water systems, where NPs can hetero-aggregate with natural organic and mineral suspended matter. Here we present the interactions and aggregation behavior of TiO2 NPs with natural organic matter (NOM) in a natural lake water. NP fate in a synthetic water of the same pH and ionic composition was also tested in the presence and absence of NOM analogs to gain insight into the different stabilizing effects of each NOM type. Several complementary analytical techniques were utilized to assess lake NOM composition, including pyrolysis−gas chromatography–mass spectrometry, gel permeation chromatography, the polarity rapid-assessment method, and Nanoparticle Tracking Analysis. In the natural lake water, the TiO2 NPs preferentially interacted with mostly anionic NOM of high and medium molecular weight (~1200–1450 and 400–520 Da). Specifically, strong interactions with proteins and polyhydroxy aromatics were observed. NP fate and stability were determined in both raw lake water containing mineral particulate matter and total NOM (NOMtot) and filtered lake water containing only NOM <0.8 μm (NOM<0.8), with different aggregation profiles observed over time. Additionally, three times the number of TiO2 NPs remained in suspension when only NOM<0.8 was present compared to the unfiltered water containing mineral particulate matter and NOMtot. These results demonstrate the contrasting NP fates in the aquatic environment according to the presence of NOMtot vs. NOM<0.8 and further suggest that the use of pure NOM analogs may not accurately represent NP interactions and fate in the natural system.
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