Light Fraction Carbon and Water-Stable Aggregates in Black Soils

The distribution of light fraction carbon （LF-C） in the various size classes of aggregates and its relationship to water- stable aggregates as well as the influence of cultivation on the organic components in virgin and cultivated black soils were studied by wet sieving and density separation methods. The total organic carbon （TOC） and LF-C were significantly higher （P≤ 0.05） in the virgin soils than in the cultivated soils. The LF-C in aggregates of different size classes varied from 0.9 to 2.5 g kg^-1 in the cultivated soils and from 2.5 to 7.1 g kg^-1 in the virgin soils, whereas the ratio of LF-C to TOC varied from 1.9% to 7.3% and from 5.0% to 12.2%, respectively. After being incubated under constant temperature and controlled humidity for three months, the contribution of LF-C to TOC sharply decreased to an amount （1.7%4.5%） close to the level in soils that had been cultivated for 20 to 25 years （1.3%-8.8%）. As a result, the larger water-stable macro-aggregates （especially 〉 1 mm） decreased sharply, indicating that the LF-C pool in virgin soils declined quickly after cultivation, which reduced the water stability of soil aggregates.

Relationship between light and heavy fractions of organic matter for several agricultural soils in China

Although numerous studies about the nature and turnover of soil organic matter（SOM） in light and heavy fractions（ LFOM and HFQM, respectively） have been made, little information is available in relation to the relationship between LFQM and HFOM, and no attempts have been made to quantify a general relationship between LFQM and HFQM for agricultural soils under field condition. Qur hypothesis is there may be an inherent relationship between LFQM and HFQM for agricultural soils under certain unaltered management practices for a long period, to this end, we therefore studied typically soils taken from different parts in China by using a simple density fractionation procedure. The results indicated that LFQM was positively correlated with LFOM/HFOM ratio for three typical soils. This information will be of particular use not only in deepening our understanding of the dynamics of SQM fractions but also in evaluating the potential of agricultural soils to sequestrate C under different management practices in a long term.

Deadwood affects the soil organic matter fractions and enzyme activity of soils in altitude gradient of temperate forests

The main objective of our study has been to determine the role of deadwood in the shaping of the amount of soil organic matter fractions in mountain forest soils.For this purpose,a climosequence approach comprising north(N)and south(S)exposure along the altitudinal gradient(600,800,1000 and 1200 m a.s.l.)was set up.By comparing the properties of decomposing deadwood and those of the soils located directly beneath the decaying wood we drew conclusions about the role of deadwood in the shaping of soil organic matter fractions and soil carbon storage in different climate conditions.The basic properties,enzymatic activity and fractions of soil organic matter(SOM)were determined in deadwood and affected directly by the components released from decaying wood.Heavily decomposed deadwood impacts soil organic matter stabilization more strongly than the less decayed deadwood and the light fraction of SOM is more sensitive to deadwood effects than the heavy fraction regardless of the location in the altitude gradient.Increase in SOM mineral-associated fraction C content is more pronounced in soils under the influence of deadwood located in lower locations of warmer exposure.Nutrients released from decaying wood stimulate the enzymatic activity of soils that are within the range of deadwood influence.

碳同位素分馏效应对深层原油来源判识的影响

深层烃源岩演化程度高,随成熟度升高,原油中生物标志化合物含量大幅度减少,影响了利用常规生物标志化合物参数进行油源对比的可靠性。针对如何更好地利用δ^(13)C_(PDB)值进行深层原油来源判识,通过渤海湾盆地济阳坳陷东营凹陷烃源岩自然演化剖面中可溶有机质、烃源岩生排烃物理模拟实验产物4种族组分δ^(13)C_(PDB)值的分析,结合烷烃质量分数特征,探讨了深层烃源岩原油碳同位素分馏效应,提出利用δ^(13)C_(PDB)值进行深层原油来源判识的工作思路和方法。深层烃源岩因高热演化程度而产生的碳同位素分馏效应是明显的,烃源岩可溶有机质的烷烃、芳烃、非烃和沥青质4种族组分δ^(13)C_(PDB)值随埋深的增加均发生了明显增大现象,其中烷烃δ^(13)C_(PDB)值变化最明显,达5‰以上,芳烃δ^(13)C_(PDB)值约为4‰,非烃和沥青质δ^(13)C_(PDB)的变化相对较小,约为2‰~3‰。随埋深的增加可溶有机质中烷烃质量分数由40%左右增至80%以上,相应烷烃δ^(13)C_(PDB)值由-30‰左右增至-24‰以上,且烷烃质量分数与其δ^(13)C_(PDB)值的变化有很好相关性。同一类型烃源岩样品生排烃物理模拟产物族组分δ^(13)C_(PDB)值也显示了相似的结果,烷烃δ^(13)C_(PDB)值的变化幅度最大可达4‰,而芳烃、非烃、沥青质的δ^(13)C_(PDB)值变化相对较小,约为1‰~3‰。利用碳同位素进行深层原油来源判识时,首先根据烷烃质量分数与烷烃δ^(13)C_(PDB)值的相关性判断是否存在热演化造成的碳同位素分馏效应,并对烷烃δ^(13)C_(PDB)值进行合理恢复,然后再利用恢复后的δ^(13)C_(PDB)值进行原油来源的合理判识。依照上述方法对准噶尔盆地西缘车排子凸起轻质油来源进行了判识,轻质油的碳同位素明显存在热演化造成的分馏效应,轻质油源自深部二叠系高成熟烃源岩的可能性很大,这对该地区油气勘探目标评价部署工作具有重要实践意义。

整合多源遥感数据的洪涝灾害评估恢复——以河南“7·20”暴雨灾害为例

洪涝灾害发生后通过植被指数和灯光指数定量评估灾后恢复情况,对灾区经济建设和生态恢复的评估具有重要科学意义。该文以河南“7·20”暴雨灾害区为研究区,基于日度和月度NPP-VIIRS数据、Sentinel-NDVI、MODIS-EVI数据和统计年鉴数据,构建归一化差异城市指数(normalized difference urban index,NDUI)来表征城市内部空间细节;基于回归模型模拟人口和国内生产总值的空间分布;从研究区的夜间灯光数据和植被覆盖数据2个不同的维度来评估洪涝灾害。结果表明:高危区和中危区总面积为1429.04 km^(2),占研究区总面积的6.06%,高危地区主要分布在郑州西部、新乡东部、安阳东部、鹤壁北部,其中郑州市受灾严重程度最高;从植被覆盖度恢复率(vegetation cover recovery rate,VCRR)来看,卫辉市、淇县、滑县、林州市等地区整体植被恢复情况较差,其VCRR的值大部分在0以下,植被覆盖有恶化趋势。NDUI与社会经济统计数据拟合精度高于0.8,表明NDUI可以在洪涝灾害发生后应用于精确位置救援和灾后针对性重建工作;NPP-VIIRS和MODIS-EVI评估洪涝灾害的结果具有很好的互补性,2种数据的有机结合进行洪涝灾害研究,对灾后救援和恢复评估均有较高的应用价值。

填闲作物还田方式对烟田土壤轻重组有机碳的影响

为了提高多年连作烟田的土壤肥力,改善土壤生态环境,在烤烟冬闲期种植油菜、冬牧70、光叶紫花苕等3种作物,同时以冬季空闲不种植任何作物为对照,采取2种方式(掩青和收割)进行处理,通过测定不同处理不同土层的土壤轻、重组有机碳含量、比例及储量,探讨填闲作物收割和掩青处理对烟田土壤轻重组有机碳的影响。结果表明,不同填闲作物和不同还田方式下土壤总有机碳、重组有机碳、轻组有机碳含量均随着土壤深度的增加而降低。与对照相比,填闲作物掩青处理能够显著增加土壤总有机碳、重组有机碳、轻组有机碳含量,尤其是冬牧70在20~40 cm土层增加比较显著,分别增加了22.3%、21.98%、27.78%;填闲作物收割处理会降低土壤轻组有机碳比例和土壤轻组有机碳储量,而掩青处理则会增加土壤轻组有机碳比例和轻组有机碳储量,其中冬牧70掩青在0~20 cm土层增加比较明显,分别增加了18.14%、40.03%。填闲作物掩青处理增加了烟田土壤的含水量和持水量、降低了土壤容重以及增加土壤轻重组有机碳储量。综合来看,冬牧70掩青处理效果最好,能显著增加土壤总有机碳和轻重组有机碳含量,油菜次之。

Soil Organic Carbon,Carbon Fractions and Nutrients as Affected by Land Use in Semi-Arid Region of Loess Plateau of China

Cropland (CP),native grassland (NG) and two shrub land treatments which were converted from cropland in 1985:seabuckthorn (Hippophae rhamnoides L.) (ST),and branchytamarisk (Tamarix ramosissima) (BT) were investigated to evaluate effects of land use conversion on soil organic carbon (SOC) and soil nutrients in the semi-arid region of the Loess Plateau of China.Total organic carbon (TOC),light fraction organic carbon (LFOC),heavy fraction organic carbon (HFOC),total N (TN),nitrate nitrogen (NO 3-N) and nitrite nitrogen (NO 2-N),ammonium nitrogen (NH + 4-N),total P,and available P (AP) were measured.The results showed that SOC in NG,ST and BT were 12.7%,27.7% and 34.8% higher than that of the cropland,respectively.LFOC,light fraction (LF) dry matter,ratio of TOC to TN (C/N) and the ratio of TOC to AP (C/P) were higher in the shrub land or native grassland than in the cropland.Cropland had the highest TN,the sum of NO 3-N and NO 2-N,TP and AP due to the use of chemical fertilizers.TOC significantly correlated with LFOC,HFOC and C/N.LFOC significantly correlated with dry matter of the LF and C/N.TN,the sum of NO 3-N and NO 2-N and AP were significantly negatively correlated with TOC and LFOC.Therefore,land use conversion from cropland to shrub land,or maybe grassland,contributed to SOC sequestration and improved soil nutrients stabilization.

Soil Organic Matter Fractions under Different Vegetation Types in Permafrost Regions along the Qinghai-Tibet Highway, North of Kunlun Mountains, China

As a key attribute of soil quality, soil organic matter(SOM) and its different fractions play an important role in regulating soil nutrient cycling and soil properties.This study evaluated the soil carbon(C) and nitrogen(N) concentrations in different SOM fractions(light– and heavy fractions,microbial biomass) under different vegetation types and analyzed their influencing factors in continuous permafrost regions along the Qinghai-Tibet Highway in the North of Kunlun Mountains, China.Soil samples were collected in pits under four vegetation types — Alpine swamp meadow(ASM), Alpine meadow(AM), Alpine steppe(AS) and Alpine desert(AD) — at the depth of 0-50 cm.The vegetation coverage was the highest at ASM and AM, followed byAS and AD.The results indicated that the concentrations of light fraction carbon(LFC) and nitrogen(LFN), and microbial biomass carbon(MBC)and nitrogen(MBN) decreased as follows: ASM > AM >AS > AD, with the relatively stronger decrease of LFC,whereas the heavy fraction carbon(HFC) and nitrogen(HFN) concentrations were lower in AS soils than in the AD soils.The relatively higher proportions of LFC/SOC and MBC/SOC in the 0-10 cm depth under the ASM soils are mainly resulted from its higher substrate input and soil moisture content.Correlation analysis demonstrated that aboveground biomass, soil moisture content, soil organic carbon(SOC) and total nitrogen(TN) positively correlated to LFC, LFN, HFC, HFN, MBC and MBN, while p H negatively correlated to LFC, LFN, HFC, HFN, MBC and MBN.There was no relationship between active layer thickness and SOM fractions, except for the LFC.Results suggested that vegetation cover, soil moisture content, and SOC and TN concentrations were significantly correlated with the amount and availability of SOM fractions, while permafrost had less impact on SOM fractions in permafrost regions of the central Qinghai–Tibet Plateau.

城市群花粉过敏网络关注度及影响因素研究

研究花粉过敏网络关注度时空特征及影响因素有利于掌握相关信息,服务民生。本文结合百度指数、气象、遥感数据,分析8个城市群2017—2021年花粉过敏网络关注度时空特征与影响因素,并采用随机森林、反向传播神经网络模型进行模拟。结果表明:(1)时空特征:关注度每年高峰期在春季(4—5月);人口聚集的城市最高,在空间上聚集,京津冀、山东半岛、长三角、珠三角城市群为热点区。(2)与影响因素关系:有效范围内,温度升高、短时雷暴雨、空气质量差、光合有效辐射吸收分量升高、夜间灯光强,关注度高;高湿、高风速、大雨、久雨,关注度低;夜间灯光相关性最高。(3)城市群方面:北方城市群的温度、沿海城市群的湿度、地形起伏大城市群的风速、南方城市群的降水、珠三角和长三角城市群的空气质量指数、珠三角和京津冀城市群的光合有效辐射吸收分量重要性大,夜间灯光都不可替代。(4)随机森林和反向传播神经网络适用于模拟关注度,各城市群R^(2)均在0.64~0.92之间,RMSE、MAE均在1以下,反向传播神经网络比随机森林模拟效果更好。成渝城市群2个模型拟合度均优,其次是京津冀、珠三角和长江中游城市群。本文的方法和结果可为花粉过敏相关工作提供参考。

Soil Aggregates, Organic Matter, and Labile C and N Fractions after 37 Years of N, P and K Applications to an Irrigated Subtropical Soil under Maize-Wheat Rotation

Abstract： Physical, chemical and biological soil properties in surface （0-5 cm） and subsurface soil （5-15 cm） were determined in a field experiment conducted with seven treatments consisted of different combinations of fertilizer N （0, 100 and 200 kg N ha^-1）, P （0, 22 and 44 kg P2O5 ha^-1） and K （0, 41 and 82 kg K2O ha^-1） applied both to summer-grown maize （Zea mays L.） and winter-grown wheat （Triticum aestivum L.） crops continuously for 37 years under irrigated subtropical conditions. Application of N, P and K significantly increased water stable aggregates and had profound effects in increasing the mean weight diameter as well as the formation of macro-aggregates, which were highest in both surface （81%） and subsurface （74%） soil layers with application of 100 kg N ＋ 22 kg P2O5 ＋ 41 kg K2O ha^-1 （N100P22K41）. The N100P22K41 treatment also enhanced total organic C （TOC） from 4.4 g kg^-1 in no-NPK control to 4.8 g kg^-1in surface layer and from 3.3 to 4.1 g kg1 in subsurface layer leading to the 20% higher TOC stocks in 0-15 cm soil. The labile C and N fractions such as water soluble C, particulate and light fraction organic matter, potentially mineralizable N and microbial biomass were also highest under the optimized balanced application of N100P22K41. Relatively higher increase in all labile fractions of C and N as proportion of TOC and total N, respectively suggested that these are potential indicators to reflect changes in management practices long before changes in TOC and TN are detectable. These results demonstrated that optimized balanced application of N, P and K is crucial for improving soil health ensuring long-term sustainability of farming systems in semiarid subtropical soils.

Conventional tillage improves the storage of soil organic carbon in heavy fractions in the Loess Plateau, China

Soil labile organic carbon （C） plays an important role in improving soil quality. The relatively stable fractions of soil organic C （SOC） represent the bulk of SOC, and are also the primary determinant of the long-term C balance of terrestrial ecosystems. Different land use types can influence the distribution patterns of different SOC fractions. However, the underlying mechanisms are not well understood. In the present study, different fractions of SOC were determined in two land use types： a grazed grassland （established on previously cultivated cropland 25 years ago, GG） and a long-term cultivated millet cropland （MC）. The results showed that C concentration and C storage of light fractions （LF） and heavy fractions （HF） presented different patterns along the soil profiles in the two sites. More plant residues in GG resulted in 91.9% higher LF storage at the 0-10 cm soil depth, further contributed to 21.9% higher SOC storage at this soil depth; SOC storage at 20-60 cm soil depth in MC was 98.8% higher than that in GG, which could be mainly attributed to the HF storage 104.5% higher than in GG. This might be caused by the long-term application of organic manure, as well as the protection from plough pan and silt- and clay-sized particles. The study indicated that different soil management practices in this region can greatly influence the variations of different SOC fractions, while the conventional tillage can greatly improve the storage of SOC by in- creasing heavy fractions.

Effects of Caragana microphylla plantations on organic carbon sequestration in total and labile soil organic carbon fractions in the Horqin Sandy Land, northern China

Afforestation is conducive to soil carbon（C） sequestration in semi-arid regions. However, little is known about the effects of afforestation on sequestrations of total and labile soil organic carbon（SOC） fractions in semi-arid sandy lands. In the present study, we examined the effects of Caragana microphylla Lam. plantations with different ages（12-and 25-year-old） on sequestrations of total SOC as well as labile SOC fractions such as light fraction organic carbon（LFOC） and microbial biomass carbon（MBC）. The analyzed samples were taken from soil depths of 0–5 and 5–15 cm under two shrub-related scenarios： under shrubs and between shrubs with moving sand dunes as control sites in the Horqin Sandy Land of northern China. The results showed that the concentrations and storages of total SOC at soil depths of 0–5 and 5–15 cm were higher in 12-and 25-year-old C. microphylla plantations than in moving sand dunes（i.e., control sites）, with the highest value observed under shrubs in 25-year-old C. microphylla plantations. Furthermore, the concentrations and storages of LFOC and MBC showed similar patterns with those of total SOC at the same soil depth. The 12-year-old C. microphylla plantations had higher percentages of LFOC concentration to SOC concentration and MBC concentration to SOC concentration than the 25-year-old C. microphylla plantations and moving sand dunes at both soil depths. A significant positive correlation existed among SOC, LFOC, and MBC, implying that restoring the total and labile SOC fractions is possible by afforestation with C. microphylla shrubs in the Horqin Sandy Land. At soil depth of 0–15 cm, the accumulation rate of total SOC under shrubs was higher in young C. microphylla plantations（18.53 g C/（m^2·a）; 0–12 years） than in old C. microphylla plantations（16.24 g C/（m^2·a）; 12–25 years）, and the accumulation rates of LFOC and MBC under shrubs and between shrubs were also higher in young C. microphylla plantations than in old C. microphylla plantations. It can be concluded that the establishment of C. microphylla in the Horqin Sandy Land may be a good mitigation strategy for SOC sequestration in the surface soils.

坡面片蚀泥沙有机碳组分及^(13)C同位素不均匀富集对水动力学参数的响应

[目的]探究片蚀泥沙轻组有机碳(LF_(OC))和重组有机碳(HF_(OC))不均匀富集的水动力学和碳同位素特征,为正确理解水蚀作用下土壤有机碳库变化提供理论与技术支撑。[方法]以陕西省咸阳市杨凌区土为研究对象,采用改进“三区”移动式变坡钢制土槽,结合人工模拟降雨技术,测定径流水动力学参数和泥沙各粒径团聚体有机碳组成及其δ^(13)C值,并辅以棕壤侵蚀泥沙有机碳δ^(13)C值和水力参数,验证土试验结果的准确性。[结果]①雨强和坡度较小时,侵蚀泥沙LF_(OC)和HF_(OC)易发生富集,且相较黏粉粒和微团聚体,大团聚体LF_(OC)与HF_(OC)含量受雨强和坡度的影响更大;②侵蚀泥沙黏粉粒中有机碳δ^(13)C值与其有机碳活跃分数(λ)呈负相关,而其他粒径团聚体有机碳δ^(13)C值与其λ呈显著正相关(p<0.05);③流速与黏粉粒λ显著正相关(p<0.05),雷诺数与各粒径团聚体有机碳δ^(13)C值均呈显著负相关(p<0.01),片蚀过程中流速越大,黏粉粒中LF_(OC)越易于优先输移,而紊流加剧则促进低δ^(13)C值团聚体有机碳的优先输移;④对于侵蚀泥沙黏粉粒,流速和雷诺数越大,其有机碳δ^(13)C值越小,λ越大;对于微团聚体和大团聚体,雷诺数越小,其有机碳δ^(13)C值与λ越大。[结论]片蚀过程中轻重组有机碳流失与流速和雷诺数密切相关。并进一步验证了^(13)C同位素对侵蚀泥沙有机碳示踪的有效性。

420 nm强脉冲光联合剥脱性点阵激光治疗重度痤疮瘢痕的美学效果研究

目的:分析420 nm强脉冲光(Intense pulsed ligh,IPL)联合剥脱性点阵激光(Ablative fractional laser,AFL)治疗重度痤疮瘢痕的美学效果。方法:选笔者医院2023年2月-2023年8月收治107例重度痤疮瘢痕患者为研究对象,按随机数字表法分为IPL组(n=35)、AFL组(n=35)及联合组(n=37)。IPL组采用420 nm IPL治疗,AFL组采用剥脱性点阵CO_(2)激光治疗,联合组采用420 nm IPL联合点阵CO_(2)激光治疗。均治疗3个疗程后,对比疗效、红斑、色素沉着、瘢痕、生活质量、皮肤屏障及不良反应发生情况。结果:联合组的有效率明显高于IPL组、AFL组,差异有统计学意义(P<0.05),但IPL组、AFL组两组间有效率比较无统计学意义(P>0.05)。治疗后,联合组的痤疮瘢痕临床评分量表(ECCA)评分<AFL组<IPL组,且联合组治疗红斑、色素沉着的有效率明显高于AFL组、IPL组(P<0.05),差异有统计学意义(P<0.05);但AFL组、IPL组两组间比较无统计学意义(P>0.05)。治疗后,联合组的皮肤病生活质量量表(DLQI)评分低于IPL组、AFL组(P<0.05),但IPL组、AFL组两组间的DLQI评分差异无统计学意义(P>0.05)。治疗后,三组皮肤含水量均较治疗前减少、经皮水分丢失量(TWEL)均增加,但三组间比较无统计学意义(P>0.05)。末次治疗结束后2个月时,三组皮肤含水量均较治疗前增加、TWEL均减少,且联合组的皮肤含水量高于IPL组、AFL组,TWEL少于IPL组、AFL组,差异均有统计学意义(P<0.05);但IPL组、AFL组两组间比较无统计学意义(P>0.05)。治疗期间,三组刺痛、潮红等不良反应发生情况比较无统计学意义(P>0.05)。结论:420 nm IPL、点阵CO_(2)激光用于重度痤疮瘢痕治疗中均有明显疗效,但两者联合治疗效果更佳,可明显改善患者红斑、色素沉着及瘢痕状况,改善皮肤病相关生活质量及皮肤屏障功能,且安全性值得肯定。

基于可见光影像的木里矿区排土场植被覆盖度提取研究

为了快速准确提取木里矿区排土场的植被覆盖度,基于无人机可见光影像,选择过绿指数、过绿减过红指数、可见光波段差异植被指数和归一化绿红差异指数,将植被指数时序图交点法和样本统计法相结合进行阈值分割,从而提取植被覆盖度,并对提取结果的精度进行验证。结果表明:可见光波段差异植被指数的提取精度最高,达到95.83%,Kappa系数为0.92。由此可见,利用可见光波段差异植被指数,将植被指数时序图交点法和样本统计法相结合的方法适用于提取木里矿区排土场的植被覆盖度且精度较高。研究结果可为高寒矿区排土场植被覆盖度的精确提取提供一定的参考。

土壤-超积累植物体系中稀土元素的空间富集-分异特征与富集机理

离子吸附型稀土矿是我国南方特色的优质稀土资源,但由于落后的采矿方式和无节制的开采,大量稀土元素(稀土元素+Y,简称稀土元素)被带入环境中,导致稀土矿区周边出现许多环境污染和植被退化问题。乌毛蕨是一种对稀土元素具有较强耐受性和超强富集能力的蕨类超积累植物,能被用于稀土污染土壤或尾矿的生态修复。本研究以离子吸附型矿区表生土壤上生长的稀土超积累植物乌毛蕨及其根际土为研究对象,通过化学消解和ICP-MS方法测定根际土、根表、根部、叶柄、叶片中稀土元素的含量,分析土壤–植物体系中稀土元素的空间分布、富集与分异特征;采用顺序提取法测定土壤中不同化学形态的稀土元素含量,同时利用微区X射线荧光光谱(μ-XRF)与扫描电镜能谱分析技术(SEM-EDS),阐明乌毛蕨对稀土元素的吸收与富集机理。化学测试结果表明,乌毛蕨对稀土元素有较强的富集和地上转运能力,富集系数(BF)和转移系数(TF)分别为2.61和2.85;植物器官富集能力顺序为:叶片(1750μg/g)>根部(512μg/g)>叶柄(56.5μg/g);植株整体稀土元素配分模式具有与根际土相似的富轻土元素和Ce负异常特征,不同的是,植株整体Eu无异常(根际土δEu=0.51);根际土壤中富集离子交换态的轻稀土离子(34%~64%,(La/Yb)N=2.36),与根系表面呈轻微富轻稀土元素((La/Yb)N=1.29)的现象暗示根际大部分轻稀土元素能以离子形式被根系吸收,重稀土元素与有机配体络合而被吸附在根系表面;稀土元素在向上迁移过程中,(La/Yb)N值下降(叶柄=27.63,叶片=17.17),揭示木质部伤流液的重稀土元素可能比轻稀土元素更容易向上迁移;μ-XRF与SEM-EDS结果显示,乌毛蕨地上部的超富集器官(叶片)将稀土元素主要储存在叶缘的表皮层细胞,且能将大部分非生理需要的稀土元素有效区室化。上述认识揭示了在离子吸附型稀土矿区表生环境中,稀土元素从土壤向植物体内迁移并在地上部富集与分异的过程、规律和主要原因,为今后利用稀土超积累植物实现植物采矿或稀土尾矿生态修复提供科学认知基础。

轻汽油醚化装置工艺流程模拟

利用稳态流程模拟软件PRO/Ⅱ,对0.4 Mt/a轻汽油醚化装置主要工艺流程进行了系统的模拟计算,介绍了软件建模的热力学方法选择、重要设备的模块选择、工艺建模过程及其主要设置。模型验证结果表明,所建模型具有较高的准确性和适用性。为实现活性烯烃最大转化率,保证碳五组分质量,利用所建模型对醚化分馏塔甲醇加注量和回流比,甲醇回收单元萃取水量、循环甲醇中水含量及萃取水中甲醇含量等参数进行了优化。结果表明,醚化分馏塔甲醇加注量控制在进料甲醇量的8.8%,醚化分馏塔回流比控制在2.0,萃取水量控制在10~11t/h,萃取水中甲醇质量分数控制在0.04%,循环甲醇中水质量分数控制在0.016%为宜。

变压吸附气体分离技术在乙苯尾气回收中的工业应用

简要介绍了当前气体分离的主要技术,从工艺原理、原料特点、产品质量、投资占地等方面对其进行对比。简述了国内某炼厂采用变压吸附技术回收乙苯尾气中的乙烷气和氢气的流程选择过程。详细介绍了乙苯尾气回收变压吸附装置的组成、原料气条件、产品及尾气性质;通过该装置开工运行数据来看,采用变压吸附技术回收乙烷气,产品纯度能达到95%(V)以上,回收率能达到99%以上。变压吸附回收碳二组分和提纯氢气技术具有流程简单、操作方便、运行方式灵活、综合能耗低等特点,适合运用在炼厂干气碳二组分回收和氢气提纯中。

基于热集成的轻烃回收装置气体分馏系统用能优化

针对轻烃回收装置气体分馏系统进行模拟分析与用能优化,并基于Aspen Plus流程模拟,探讨了进料温度、回流比对系统能耗的影响。考虑到炼化低温余热相对富余,结合工艺分析和精馏序列优化,并改善热源、热阱的不匹配性,降低脱乙烷塔和脱丁烷塔塔底温度,提出了集成热媒水系统、热泵系统的气体分馏改进工艺以降低装置能耗,并对改进前后的能效和经济性进行了对比分析。结果表明:4种改进方案均可降低气体分馏系统能耗15.61%以上,年净效益151.80万元以上。集成热媒水系统的改进工艺㶲耗量降低0.52 MW,降幅达40.95%,年净效益400.57万元,投资回收期为0.42 a。集成直接式热泵系统的改进工艺方案改进效果最佳,过程㶲耗量降低0.67 MW,降幅达53.04%,年净效益498.18万元,投资回收期为1.41 a。

强脉冲光联合点阵CO_(2)激光治疗皮肤光老化疗效分析

目的:探究强脉冲光联合点阵CO_(2)激光在光老化患者皮肤中的应用效果。方法:选取2020年6月-2022年7月笔者医院收治的135例光老化患者为研究对象,随机分为观察组(45例)、点阵CO_(2)激光组(45例)及强脉冲光组(45例),其中点阵CO_(2)激光组给予点阵CO_(2)激光治疗,强脉冲光组给予强脉冲光治疗,观察组给予强脉冲光联合点阵CO_(2)激光治疗。比较三组光老化患者皮肤质地、屏障功能及色素沉着情况。结果:观察组治疗总有效率(93.33%)、面部皮肤色素沉着治疗的总有效率、安全性、治疗舒适度、近期美观度及远期效果维持度评分显著高于点阵CO_(2)激光组(75.56%)、强脉冲光组(73.33%);点阵CO_(2)激光组与强脉冲光组比较差异无统计学意义(P>0.05)。与治疗前比较,三组治疗后皮肤色斑、纹理、皱纹、毛孔、紫质评分均显著降低,且观察组显著低于强脉冲光组及点阵CO_(2)激光组(P<0.05);与治疗前比较,治疗后观察组皮肤pH值显著降低,且明显低于强脉冲光组、点阵CO_(2)激光组。与治疗前比较,三组治疗后经皮水分丢失显著降低,皮肤含水量、油脂含量显著升高,且观察组改善效果明显强脉冲光组、点阵CO_(2)激光组(P<0.05);观察组不良反应的总发生率显著低于点阵CO_(2)激光组、强脉冲光组(P<0.05),点阵CO_(2)激光组与强脉冲光组比较差异无统计学意义(P>0.05)。结论:强脉冲光联合点阵CO_(2)激光治疗光老化患者可有效改善患者皮肤质地,修复皮肤屏障,减少皮肤色素沉着,效果显著。