生物质炭中的污染物含量及其田间施用的环境风险预测

生物质炭在碳固定、污染修复和酸性土壤改良中的应用非常广泛,但对生物质炭中所含污染物的研究甚少,其在田间应用中的环境风险并不清楚。该文选择松针和麦秆为原料,采用不同制备方法,研究了不同条件下获得的生物质炭中的重金属和多环芳烃含量,并初步评估了其田间应用的环境风险。研究表明,不同有机废弃物来源制备的生物质炭中均含有一定量的重金属(0.301～128mg/kg)和多环芳烃(1.48～5.48mg/kg);松针制备的生物质炭中的重金属含量普遍高于麦秆制备的生物质炭,而多环芳烃含量则相反,且高温制备有助于降低生物质炭中的多环芳烃含量;在低施用量的田间条件下,生物质炭的施用不易对土壤造成多环芳烃的环境风险,但在高施用量条件下,生物质炭中含有的多环芳烃容易使土壤中多环芳烃含量达到中度或重度污染的程度;生物质炭中的重金属在土壤中的积累量比较有限,环境风险较小。     

Enhanced bioremediation of PAH-contaminated soil by immobilized bacteria with plant residue and biochar as carriers

Purpose

Polycyclic aromatic hydrocarbons (PAHs) are largely accumulated in soils in China. The immobilized-microorganism technique (IMT) is a potential approach for abating soil contamination with PAHs. However, few studies about the application of IMT to contaminated soil remediation were reported. Due to recalcitrance to decomposition, biochar application to soil may enhance soil carbon sequestration, but few studies on the application of biochars to remediation of contaminated soil were reported. In this study, we illustrated enhanced bioremediation of soil having a long history of PAH contamination by IMT using plant residues and biochars as carriers.

Materials and methods

Two PAH-degrading bacteria, Pseudomonas putida and an unidentified indigenous bacterium, were selected for IMT. The extractability and biodegradation of 15 PAHs in solution and an actual PAH-contaminated soil amended with immobilized-bacteria materials were investigated under different incubation periods. The effects of carriers and the molecular weight of PAHs on bioremediation efficiency were determined to illustrate their different bio-dissipation mechanisms of PAHs in soil.

Results and discussion

The IMT can considerably enhance the removal of PAHs. Carriers impose different effects on PAH bio-dissipation by amended soil with immobilized-bacteria, which can directly degrade the carrier-associated PAHs. The removal of PAHs from soil depended on PAH molecular weight and carrier types. Enhanced bio-dissipation by IMT was much stronger for 4- and 5-ring PAHs than for 3- and 6-ring ones in soil. Only P400 biochar-immobilized bacteria enhanced bio-dissipation of all PAHs in contaminated soil after a 90-day incubation.

Conclusions

Biochar can promote bioremediation of contaminated soil as microbial carriers of IMT. It is vital to select an appropriate biochar as an immobilized carrier to stimulate biodegradation. It is feasible to use adsorption carriers with high sorptive capabilities to concentrate PAHs as well as microorganisms and thereby enhance dissipation of PAHs and mitigate soil pollution.     

Biochar reduces uptake and accumulation of polycyclic aromatic hydrocarbons (PAHs) in winter wheat on a PAH-contaminated soil

For years, biochar has been successfully used for the remediation of polycyclic aromatic hydrocarbons(PAHs) in contaminated soils, not only for improving their removal from soil but also for reducing their uptake by crops. However, the underlying mechanism of biochar application reducing PAH uptake and accumulation in winter wheat remains unclear. Pot trials were conducted on a PAH-contaminated soil amended with bamboo biochar, coconut shell biochar,and maize straw biochar(MSB) for an entire gro...     

生物质炭热解炭化条件及其性质的文献分析

【目的】因生物炭具有对土壤固碳减排和作物增产以及环境修复的作用，已受到国内外学者的广泛关注。本文回顾近年来生物质炭性质的相关研究，分析农业应用中生物质炭性质问题，阐述未来生物质炭性质研究发展趋势。【方法】收集了截至2015年12月文献出版物中402篇文献，对数据按生物质炭来源地区、生产 (制备) 条件和性质类别进行分类评价。【结果】1) 目前研究中应用的生物质炭68.2%为实验室制备，商业化生产比例只有22.9%；2) 生物质炭原料以林木为主，占44.3%，其次是农作物剩余物，占38.6%。作物秸秆制备的生物质炭以中国研究最多；3) 制备生物质炭的炭化温度范围在300～700℃ (91.4%)，400～600℃的温度范围以商业化生产中较常用；4) 生物质炭性质测定除总 (有机) 碳外，常测指标还包括pH、电导率、总氮、灰分和比表面积等，潜在污染物指标测定较少，而污泥炭中的重金属及植物源炭的多环芳烃潜在风险仍需研究；5) 生物质炭的研究制备原料基本上取决于该区域内可收集的废弃物，欧美地区主要关注林木生物质炭，亚洲等的发展中国家则着重研究秸秆生物质炭。【结论】与欧美国家相比，发展中国家的生物质炭商品化生产仍较薄弱。不同原料和温度生产的生物质炭性质和功能差别很大，以秸秆为原料、中温炭化的生物质炭各方面性质较为平衡，具备生物质炭大规模产业化的条件。此外，生物质炭性质的测试注重理化性状，对潜在风险污染物的分析普遍不足，亟需开发一个标准来规范生物质炭最小测试指标集和合适的测试方法选择。     

Dissipation and sorption processes of polycyclic aromatic hydrocarbons (PAHs) to organic matter in soils amended by exogenous rich-carbon material

Purpose

The aim of the research was to assess the effect of biochar addition on aging, degradation, and sorption processes of polycyclic aromatic hydrocarbons (PAHs) to soil organic matter. The study was carried out as a sorption experiment in strictly controlled water and air conditions, which allowed for the accurate observation and prediction of PAH behavior in soils.

Materials and methods

Four soils were fortified with a PAH mixture (Fluorene-Flu, Anthracene-Ant, Phenanthrene-Phe, Pyrene-Pyr, Chrysene-Chry) at 20 mg kg^?1 of single-compound concentration level. The experiment was carried out in two trials: soils?+?5PAHs amended with biochar and soil?+?5PAHs without biochar addition with incubation times of 0, 1, 3, 6, and 9 months. After each interval time, the extractable (E-SOM) and stable organic matter (S-SOM) were measured as well as PAHs determined in two forms: total concentration (PAH-tot) and residual concentration (PAH-rest) after E-SOM extraction. The PAH loss and half-life times were estimated according to pseudo first-order kinetics equation.

Results and discussion

The amounts of PAH-tot in the soils without biochar decreased by an average of 92%, while in soil with biochar, this was 41% after 9 months of aging. The amount of PAHs-rest bounded with S-SOM after 9 months of incubation varied from 0.9 to 3.5% and 0.2 to 1.3% of the initial PAH concentration, respectively, for soils non-induced and induced by biochar. In soils without biochar, Flu, Ant, Phe, and Pyr exhibited similar T_1/2 (43–59 days), but Chry was characterized by a much higher and broader T_1/2 than other hydrocarbons (67–280 days). Biochar addition to the soils significantly influenced the half-life changes for all PAHs. The highest changes were noted for Phe (14-fold increase), and the lowest was for Flu (7-fold increase).

Conclusions

The addition of exogenous-rich carbon material such as biochar to the soil significantly changes the behavior and sorption potential of PAHs in the soil. Soils enriched with biochar are characterized by a higher persistence of PAHs, longer aging time, and lower affinity for sorption by native organic matter structures. Soils freshly polluted by PAH are mainly sorbed by E-SOM, which significantly increases their accessibility and reduces formation of bound-residues in the soil.

     

低温水热法制备竹生物炭及其对有机物的吸附性能

竹是一类常见的生物质资源,竹加工中产生的废弃物是制生物炭的理想原料。该研究采用水热炭化法,在较低的水热温度下制备竹生物炭,并通过Na OH浸泡和N2氛围下高温煅烧2种方法,对竹生物炭进行进一步改性,所得产品用于去除水溶液中2-萘酚和刚果红。结果显示:仅采用水热炭化得到的竹生物炭产品得率大于54%,表面官能团丰富,均能吸附水溶液中的2-萘酚和刚果红,其中160℃3 h下制备的样品对2-萘酚吸附效果最好,200℃7 h下制备的样品对刚果红吸附效果最好;改性处理会降低终产品得率并影响表面官能团,Na OH浸泡改性处理能增加竹生物炭对2-萘酚和刚果红的吸附容量,N2氛围下高温煅烧改性则不能提高竹生物炭对这2种物质的吸附效果。研究结果可为废弃生物质制炭及生物炭在水污染物吸附分离中的应用提供参考。     

Retention of heavy metals by carboxyl functional groups of biochars in small arms range soil

Long-term effectiveness of biochar for heavy metal stabilization depends upon biochar's sorptive property and recalcitrance in soil. To understand the role of carboxyl functional groups on heavy metal stabilization, cottonseed hull biochar and flax shive steam-activated biochar having a low O/C ratio (0.04-0.06) and high fixed carbon content (~80% dry weight basis) were oxidized using concentrated H(2)SO(4)/HNO(3) and 30% HNO(3). Oxidized and unoxidized biochars were characterized for O/C ratio, total acidity, pH, moisture, ash, volatile matter, and fixed carbon contents, Brunauer-Emmett-Teller surface area, and attenuated total reflectance Fourier transform infrared spectral features. Characterized biochars were amended (2%, 5%, 10%, and 20% in grams of biochar per gram of soil) on a sandy, slightly acidic (pH 6.27) heavy metal contaminated small arms range soil fraction (<250 μm) having low total organic carbon (0.518%) and low cation exchange capacity (0.95 cmol(c) kg(-1)). Oxidized biochars rich in carboxyl functional groups exhibited significantly greater Pb, Cu, and Zn stabilization ability compared to unoxidized biochars, especially in pH 4.9 acetate buffer (standard solution for the toxicity characteristic leaching procedure). Oppositely, only oxidized biochars caused desorption of Sb, indicating a counteracting impact of carboxyl functional groups on the solubility of anions and cations. The results suggested that appropriate selection of biochar oxidant will produce recalcitrant biochars rich in carboxyl functional groups for a long-term heavy metal stabilization strategy in contaminated soils.     

生物质炭中多环芳烃的潜在环境风险研究进展

作为土壤改良剂和环境污染修复材料,生物质炭在近年来得以广泛应用。生物质炭制备过程中会产生一定量的多环芳烃(PAHs),对其潜在环境负面效应和风险尚缺乏应有的认识。本文总结了生物质炭中PAHs的形成机理、影响因素(包括原材料、裂解温度、裂解升温速率和保留时间等)、总量和生物有效含量及其分析方法,旨在为生物质炭在环境中的安全应用提供理论依据和技术参考。     

Rice Straw-Derived Biochar Properties and Functions as Cu(Ⅱ) and Cyromazine Sorbents as Influenced by Pyrolysis Temperature

In this study, biochars from rice straw(Oryza sativa L.) were prepared at 200–600?C by oxygen-limited pyrolysis to investigate the changes in properties of rice straw biochars produced at different temperatures, and to examine the adsorption capacities of the biochars for a heavy metal, copper(Ⅱ)(Cu(Ⅱ)), and an organic insecticide of cyromazine, as well as to further reveal the adsorption mechanisms.The results obtained with batch experiments showed that the amount of Cu(Ⅱ) adsorbed varied with the pyrolysis temperatures of rice straw biochar. The biochar produced at 400?C had the largest adsorption capacity for Cu(Ⅱ)(0.37 mol kg-1) among the biochars,with the non-electrostatic adsorption as the main adsorption mechanism. The highest adsorption capacity for cyromazine(156.42 g kg-1) was found in the rice straw biochar produced at 600?C, and cyromazine adsorption was exclusively predominated by surface adsorption. An obvious competitive adsorption was found between 5 mmol L-1Cu(II) and 2 g L-1cyromazine when they were in the binary solute system. Biochar may be used to remediate heavy metal- and organic insecticide-contaminated water, while the pyrolysis temperature of feedstocks for producing biochar should be considered for the restoration of multi-contamination.     

Effect of Three Different Qualities of Biochar on Selected Soil Properties

An incubation study was conducted to determine how biochar interacts with a nitrogen fertilizer and how it reacts in the soil as well as to measure the effect of different biochars on soil chemical properties. Two Iowa soils, Nicollet surface soil (fine-loamy, mixed, superactive, mesic Aquic Hapludoll) and Storden subsoil (fine-loamy, mixed, superactive, mesic Eutrudept), were mixed with three different qualities of biochar and a nitrogen fertilizer (urea). The biochar was created from corn stover that was pyrolized with three different amounts of atmospheric air: 0% (biochar 1), 10% (biochar 2), and 25% (biochar 3). Soil tests for pH, total nitrogen (N), extractable phosphorus (P), extractable potassium (K), ammonium N, nitrate N, organic matter, and total carbon (C) were performed. The different biochars significantly affected the total N, total organic C, and pH in both soils at all rates of urea applied. The conditions during pyrolysis influenced how the biochar/fertilizer reacted with the soil.     

Effect of biochar amendment on soil carbon balance and soil microbial activity

We investigated the behavior of biochars in arable and forest soil in a greenhouse experiment in order to prove that these amendments can increase carbon storage in soils. Two qualities of biochar were produced by hydrothermal pyrolysis from ¹³C labeled glucose (0% N) and yeast (5% N), respectively. We quantified respiratory losses of soil and biochar carbon and calculated mean residence times of the biochars using the isotopic label. Extraction of phospholipid fatty acids from soil at the beginning and after 4 months of incubation was used to quantify changes in microbial biomass and to identify microbial groups utilizing the biochars. Mean residence times varied between 4 and 29 years, depending on soil type and quality of biochar. Yeast-derived biochar promoted fungi in the soil, while glucose-derived biochar was utilized by Gram-negative bacteria. Our results suggest that residence times of biochar in soils can be manipulated with the aim to “design” the best possible biochar for a given soil type.     

土壤微生物对不同粒径、不同表面和孔隙性质生物炭的响应

Biochars are known for their heterogeneity, especially in pore and surface structure associated with pyrolysis processes and sources of feedstocks. The surface area of biochar is likely to be an important determinant of the extent of soil microbial attachment, whereas the porous structure of biochar is expected to provide protection for soil microorganisms. Potential interactions between biochars from different sources and with different particle sizes were investigated in relation to soil microbial properties in a short-term incubation study. Three particle size(sieved) fractions(0.5–1.0, 1.0–2.0 and 2.0–4.0 mm) from three woody biochars produced from jarrah wood,jarrah and wandoo wood and Australian wattle branches, respectively, were incubated in soil at 25?C for 56 d. Observation by scanning electron microscopy(SEM) and characterisation of pore and surface area showed that all three woody biochars provided potential habitats for soil microorganisms due to their high porosity and surface areas. The biochars were structurally heterogeneous,varying in porosity and surface structure both within and between the biochar sources. After the 56-d incubation, hyphal colonisation was observed on biochar surfaces and in larger biochar pores. Soil clumping occurred on biochar particles, cementing and covering exposed biochar pores. This may have altered surface area and pore availability for microbial colonisation. Transient changes in soil microbial biomass, without a consistent trend, were observed among biochars during the 56-d incubation.     

Positive and negative carbon mineralization priming effects among a variety of biochar-amended soils

Pyrogenic carbon (biochar) amendment is increasingly discussed as a method to increase soil fertility while sequestering atmospheric carbon (C). However, both increased and decreased C mineralization has been observed following biochar additions to soils. In an effort to better understand the interaction of pyrogenic C and soil organic matter (OM), a range of Florida soils were incubated with a range of laboratory-produced biochars and CO₂ evolution was measured over more than one year. More C was released from biochar-amended than from non-amended soils and cumulative mineralized C generally increased with decreasing biomass combustion temperature and from hardwood to grass biochars, similar to the pattern of biochar lability previously determined from separate incubations of biochar alone.The interactive effects of biochar addition to soil on CO₂ evolution (priming) were evaluated by comparing the additive CO₂ release expected from separate incubations of soil and biochar with that actually measured from corresponding biochar and soil mixtures. Priming direction (positive or negative for C mineralization stimulation or suppression, respectively) and magnitude varied with soil and biochar type, ranging from −52 to 89% at the end of 1 year. In general, C mineralization was greater than expected (positive priming) for soils combined with biochars produced at low temperatures (250 and 400 °C) and from grasses, particularly during the early incubation stage (first 90 d) and in soils of lower organic C content. It contrast, C mineralization was generally less than expected (negative priming) for soils combined with biochars produced at high temperatures (525 and 650 °C) and from hard woods, particularly during the later incubation stage (250-500 d). Measurements of the stable isotopic signature of respired CO₂ indicated that, for grass biochars at least, it was predominantly pyrogenic C mineralization that was stimulated during early incubation and soil C mineralization that was suppressed during later incubation stages. It is hypothesized that the presence of soil OM stimulated the co-mineralization of the more labile components of biochar over the short term. The data strongly suggests, however, that over the long term, biochar-soil interaction will enhance soil C storage via the processes of OM sorption to biochar and physical protection.     

Application of Biochar and Compost for Enhancement of Rice (Oryza Sativa L.) Grain Yield in Calcareous Sandy Soil

The application of compost to calcareous soils by farmers is a well-established practice and has been shown to improve yields. However, incorporation of biochar and mixture of biochar and compost into calcareous soils is a relatively novel concept for improving soil quality and yield since calcareous soils comprise a large scale of soils worldwide. The objective of this study was to determine the effects of the co-application of biochar and compost on the soil properties, nutrient status and grain yield of rice in calcareous sandy soil. The experiment was conducted in a factorial arrangement based on randomized complete block design with three replications. The compost application rates were 1% and 3% (w/w; compost/soil) and the applied rates of biochars (rice straw biochar, RSB; sugarcane bagasse biochar, SBB) were 0.3% and 0.9% (w/w; biochar/soil). The results showed that soil pH decreased with increasing application rates of either compost or biochars. However, soil EC was enhanced through increasing the application rates of compost and biochars. The co-application of biochar and compost improved soil total N and available P concentrations. The soil available K increased with increasing the rate of incorporated biochars and compost. An increase of soil available K was more predominate with the application of RSB than SBB. The RSB, also, added a considerable amount of silicon (Si) to the soil. The co-incorporation of biochars and compost enhanced soil available concentrations of Fe, Zn, Cu, and Mn as well. The RSB was more effective than the SBB in grain yield enhancement almost certainly due to a higher Si content in RSB. Furthermore, the concurrent application of biochars and compost increased grain yield more than applying them individually. A higher application rate of biochar and compost induced a higher grain yield. The co-application of highest rates of RSB (0.9%) and compost (3%) induced the highest grain yield (26.1 g/pot) among the treatments. The increase in yield compare to the control were 321% and 260% for 0.9% RSB + 3% compost and 0.9% SBB + 3% compost, respectively. The increase in the grain yield was due to an improvement in the soil chemical properties and nutrients enhancement. Finally, the co-application of the highest rate of RSB (0.9%) and compost (3%) is recommended to obtain the appropriate rate of rice grain yield in calcareous sandy soil.     

Short term soil priming effects and the mineralisation of biochar following its incorporation to soils of different pH

The aim of this work was to determine the magnitude of the priming effect, i.e. short-term changes in the rate (negative or positive) of mineralisation of native soil organic carbon (C), following addition of biochars. The biochars were made from Miscanthus giganteus, a C4 plant, naturally enriched with ¹³C. The biochars were produced at 350 °C (biochar350) and 700 °C (biochar700) and applied with and without ryegrass as a substrate to a clay-loam soil at pH 3.7 and 7.6. A secondary aim was to determine the effect of ryegrass addition on the mineralisation of the two biochars.After 87 days, biochar350 addition caused priming effects equivalent to 250 and 319 μg CO₂-C g⁻¹ soil, in the low and high pH soil, respectively. The largest priming effects occurred at the start of the incubations. The size of the priming effect was decreased at higher biochar pyrolysis temperatures, which may be a way of controlling priming effects following biochar incorporation to soil, if desired. The priming effect was probably induced by the water soluble components of the biochar. At 87 days of incubation, 0.14% and 0.18% of biochar700 and 0.61% and 0.84% of biochar350 were mineralized in the low and high pH soil, respectively. Ryegrass addition gave an increased biochar350 mineralisation of 33% and 40%, and increased biochar700 at 137% and 70%, in the low and high pH soils, respectively. Certainly, on the basis of our results, if biochar is used to sequester carbon a priming effect may occur, increasing CO₂-C evolved from soil and decreasing soil organic C. However, this will be more than compensated for by the increased soil C caused by biochar incorporation. A similar conclusion holds for accelerated mineralisation of biochar due to incorporation of fresh labile substrates. We consider that our results are the first to unequivocally demonstrate the initiation, progress and termination of a true positive priming effect by biochar on native soil organic C.     

Sorption and desorption of phosphate on biochar and biochar–soil mixtures

The term biochar refers to materials with diverse chemical, physical and physicochemical characteristics that have potential as a soil amendment. The purpose of this study was to investigate the P sorption/desorption properties of various slow biochars and one fast pyrolysis biochar and to determine how a fast pyrolysis biochar influences these properties in a degraded tropical soil. The fast pyrolysis biochar was a mixture of three separate biochars: sawdust, elephant grass and sugar cane leaves. Three other biochars were made by slow pyrolysis from three Amazonian tree species (Lacre, Ingá and Embaúba) at three temperatures of formation (400 °C, 500 °C, 600 °C). Inorganic P was added to develop sorption curves and then desorbed to develop desorption curves for all biochar situations. For the slow pyrolysis, the 600 ºC biochar had a reduced capacity to sorb P (4–10 times less) relative to those biochars formed at 400 °C and 500 °C. Conversely, biochar from Ingá desorbed the most P. The fast pyrolysis biochar, when mixed with degraded tropical mineral soil, decreased the soil's P sorption capacity by 55% presumably because of the high soluble, inorganic P prevalent in this biochar (909 mg P/kg of biochar). Phosphorus desorption from the fast pyrolysis biochar/soil mixture not only exhibited a common desorption curve but also buffered the soil solution at a value of ca. 0.2 mg/L. This study shows the diversity in P chemistry that can be expected when biochar is a soil amendment and suggests the potential to develop biochars with properties to meet specific objectives.     

碳酸钾添加比例对玉米秸秆生物炭表面特性的影响

在600℃的热解温度下通过添加不同比例的碳酸钾制备活性生物炭。对比分析了碳酸钾活化生物炭(KBC)和普通生物炭(BC)的特性,包括生物炭红外光谱特征、表面官能团、比表面积和孔径分布及吸附动力学过程等。结果表明,经碳酸钾活化的生物炭比表面积大为提高,最高达到566 m2 g-1(KBC-2-600),而普通生物炭(BC600)的比表面积仅为86.8 m2 g-1,KBC600系列的介孔容积和微孔容积均显著高于BC600,介孔容积平均扩大了16倍,微孔容积平均扩大了4倍,同时提高了微孔率。经碳酸钾活化的生物炭表面官能团的数量和饱和度发生改变,在1 256 cm-1~3 414 cm-1处,官能团的总体含量均低于普通生物炭,酯类羰基消失,形成氢键的能力减弱,非饱和醚类增加,芳香性和非极性提高,此表面特征更有利于吸附非极性芳香类污染物。对萘吸附的动力学实验表明,BC600和KBC-4-600均适合以二级动力学模型拟合,经碳酸钾活化后,生物炭的吸附性能提高,颗粒内扩散模型拟合结果表明,经碳酸钾活化后,生物炭内部孔隙复杂程度和数量均得到提高。碳酸钾活化的生物炭表面性质优良,作为高效吸附剂用于修复非极性芳香类污染有很大潜力。     

不同种类生物质炭对植烟土壤保育及烤烟生长和品质的影响

通过盆栽试验,研究施加等量(3%)椰壳炭、竹炭、猪炭和烟秆炭对植烟土壤基本理化性质、土壤养分、烤烟生长状况以及烤烟常规化学成分的影响。结果表明:施用生物质炭对土壤电导率、有效养分含量、有机碳含量和酶活性有显著影响,其中施用竹炭后土壤有机碳含量较CK增幅最大,达146.37%;而施加猪炭能显著提高植烟土壤中电导率、有效磷、速效钾含量以及过氧化氢酶和脲酶的活性(p0.05)。生物质炭对烤烟农艺性状的影响较小,仅在猪炭处理下,烤烟茎围较对照增加0.78cm。施用生物质炭能显著提高烤烟的生物量(p0.05),其中猪炭和烟秆炭处理下烤烟叶片干质量较CK分别提高了58.07%和47.01%。另外,在施用竹炭、猪炭和烟秆炭后,烤烟叶片中烟碱、总氮、还原糖和钾均处于优质烟叶适宜范围内。猪炭处理还可以显著提高烟叶氯含量(p0.05),并使烤后烟叶糖碱比和氮碱比达到优质烟叶标准。综上所述,在各类生物质炭中,施用猪炭和烟秆炭对于改善植烟土壤理化性质和养分状况、提高烤烟产量和品质的效果较好。     

Chemically and biologically activated biochars slow down urea hydrolysis and improve nitrogen use efficiency

Biochar is considered a potential technology to enhance chemical fertilizer use efficiency through intensification of the interactions between nutrients and the functional groups on biochar surfaces. However, little is known about how the application of activated biochars mixed with urea influences nitrogen(N) mineralization and crop performance in paddy fields. Here, a sawdust-derived fresh biochar (FBC)(ca. 400?C) was activated chemically with 15%hydrogen peroxide and biologically with a nutri...     

Assessment of polycyclic aromatic hydrocarbon content of smoked fish by means of a fast HPLC/HPLC method

Polycyclic aromatic hydrocarbon (PAH) concentrations in smoked food can reach levels hazardous for the human health, especially when the smoking procedure is carried out under uncontrolled conditions. In this work a simple and rapid method for the determination of PAHs in smoked fish samples is described. PAHs were extracted from the insoluble samples (together with fat substances) by homogenization with acidified chloroform. The fat extract was then submitted to a first LC sample preparation step (performed on a large silica column) to isolate PAHs from triglycerides. After reconcentration, the PAH fraction was finally injected into the reverse-phase analytical column. The proposed method, which presents good characteristics of recoveries and repeatability, was also used to analyze PAH content of some smoked trout samples packed under vacuum.