黄河三角洲人工草场群落土壤盐分动态集成预报模型及其应用

提出了以ＧＭ（１,１）模型拟合发展的趋势、傅里叶变换撮周期分量ＡＲ（ｐ）模型模拟随机过程的集成预报模型,并用于黄河三角洲人工草场群落土壤盐分的定量研究中,经理论和应用检验证明：该模型能以较高的精度模拟或预报土壤盐分在较长时期内的动态变化过程,方法简单,计算工作量小,并优于传统的单一预报模型。     

Unexpected/contrary behavior of aerosol mass concentration in response to the individual components’ concentration reduction in Kitakyushu, Japan

In the suburbs of Kitakyushu, Japan, the inorganic aerosol mass concentration (IAM) was about 32.7 µg/m³, with the aerosol pH of 3.3. To study the thermodynamics of aerosol when its individual components’ concentration is reduced, sensitive tests were performed using the ISORROPIA II model, in which the seven control species—TNaCl, TNH₄⁺, TSO₄²⁻, TNO₃⁻, TMg²⁺, TK⁺, and TCa²⁺—were taken into account. IAM and inorganic aerosol pH after reducing TNaCl, TNO₃⁻, TMg²⁺, TK⁺, and TCa²⁺ responded linearly (0% ≤ concentration reduction ratio (CRR) ≤ 100%, with the exception of 100% in TNaCl); the nonlinear variations of these two parameters could be observed by controlling TNH₄⁺ and TSO₄²⁻. Unexpected aerosol behavior occurred at 100% reduction of TNaCl, which was caused by the sudden increase of NO₃⁻, NH₄⁺, and aerosol liquid water content (ALWC); the increase of IAM was also observed after controlling TSO₄²⁻ (60% ≤ CRR ≤ 100%) and TCa²⁺ (0% ≤ CRR ≤ 100%), which was mainly related to the variation of ALWC driven by the response of CaSO₄. Multiple regression analysis showed that ALWC was statistically and strongly related to the variations of NO₃⁻, Cl⁻, SO₄²⁻, HSO₄⁻, HNO₃, and NH₃ (P < 0.05), with regression coefficients of 1.68, 5.23, 1.83, 2.81, 0.34, and 0.57, respectively. The highest coefficient (5.23) was found for Cl⁻, revealing that sea salts significantly influenced particle responses. Overall, this study comprehensively investigated aerosol characteristics and inner responses for the reduction of components, which is of great significance for a better understanding of atmospheric chemistry in Kitakyushu, Japan.     

CeO2/g-C3N4光催化剂的制备及性能

通过液相沉积法制备了CeO2/g-C3N4复合光催化剂,利用X射线衍射、氮气吸脱附、紫外可见漫反射等方法对其进行了表征,考察了CeO2/g-C3N4复合光催化剂在可见光下降解罗丹明B的光催化活性,并对光催化反应机理进行了初步探讨. 结果表明,复合光催化剂中g-C3N4和CeO2分别为石墨相和萤石相,其中存在堆积介孔结构,随着CeO2掺杂量的增加,CeO2/g-C3N4复合光催化剂的比表面积逐渐增大. CeO2掺杂提高了光生电子-空穴对的分离效率,使得CeO2/g-C3N4复合光催化剂的活性比单纯g-C3N4有所提升,其中CeO2掺杂量为6%的复合光催化剂活性最高,在可见光照射150 min后对罗丹明B染料的降解率可达94%.在复合光催化剂对罗丹明B的降解过程中,光生空穴是主要的活性物种.     

Evaluation of the aggressive potential of marine chloride and sulfate salts on mortars applied as renders in the Metropolitan Region of Salvador--Bahia, Brazil

In recent years, growing interest has focused on determining the performance of materials and evaluating the service life of structures exposed to various environmental forces. In this context, the determination of the aggressive potential of marine salts on mortars used as external renders is critical. The present study aimed to evaluate the spatial distribution of marine salts relative to distance from the sea. This was done by monitoring the deposition rate of chlorides and sulfates in wet candle sensors, located at nine stations scattered around the Metropolitan Region of Salvador, state of Bahia, Brazil. The study also determined the effectiveness of water-soluble salts at penetrating three different types of mortars of varying cement content via deposition and diffusion. The methodology employed enabled an evaluation of the efficiency of the monitoring sensors' measurement of the aggressiveness potential of local marine aerosol, and determination of the comparative performance of the three mortars tested, from the standpoint of resistance to salt penetration. The type and amount of salts captured both in solution and in powder samples extracted from the mortars were determined by ion chromatography. The analysis of the various types of mortars tested indicated which types are more resistant to the aggressive potential of the region's marine aerosol and the distance from the shore where local buildings are liable to be most strongly affected.     

钙钛矿型La_(0.8)Ce_(0.2)Fe_(1-x)Co_xO_3催化剂的制备及其三效催化活性

采用自燃烧法制备了一组钙钛矿型复合氧化物La_(0.8)Ce_(0.2)Fe_(1-x)Co_xO_3(x=0.9,0.7,0.5,0.3,0.1),并考察了其对CO、C_3H_6和NO的三效催化活性。XRD和SEM表征结果显示,La_(0.8)Ce_(0.2)Fe_(1-x)Co_xO_3具有良好的钙钛矿型晶体结构,晶粒大小为纳米级并自组装成片状结构。催化剂的比表面积为14.73~22.43 m~2/g,含有微孔和介孔结构。催化活性评价结果表明:La_(0.8)Ce_(0.2)Fe_(0.1)Co_(0.9)O_3具有很好的三效催化活性,在理论空燃比的条件下,CO、C_3H_6和NO的起燃温度分别为195℃、264℃和290℃,完全转化温度分别为239℃、418℃和415℃,低温三效催化活性良好;Fe和Co的掺杂量同时影响着La_(0.8)Ce_(0.2)Fe_(1-x)Co_xO_3的催化效果。     

Ce3+与Cu2+协同强化芬顿体系氧化苯酚的效能与机制研究

研究了Ce~(3+)与Cu~(2+)协同强化芬顿体系在不同初始条件下对水中苯酚的氧化效能与机制.结果表明,在p H适用范围的宽度和H_2O_2浓度变化方面,Ce~(3+)/Cu~(2+)/Fe~(2+)/H_2O_2体系比传统的芬顿体系更具有优势,该体系在p H=5.0、H_2O_2浓度为2.0mmol·L-1的条件下,仍可以对苯酚保持相对较高的氧化效能;Cu~(2+)可能会借助反应过程中的中间产物(醌类物质)生成Cu+,Cu+催化H_2O_2分解生成·OH,Ce~(3+)可能促进体系内醌类物质的形成,加快Fe~(3+)与Fe~(2+)的循环效能,在一定程度上提高了芬顿体系中H_2O_2分解生成·OH的速率,说明Cu~(2+)与Ce~(3+)对芬顿体系的强化作用具有协同性;自由基终止剂依然可以抑制Ce~(3+)、Cu~(2+)强化的芬顿体系对苯酚的降解,由此说明体系中起到氧化作用的活性物种仍然是羟基自由基(·OH).     

CeO2负载型双金属Pd/Fe催化还原四氯化碳的实验研究

实验采用共沉淀法制得CeO_2负载型双金属Pd/Fe催化剂,并对催化剂的结构特征进行了X射线衍射(XRD)和扫描电子显微镜(SEM)分析.使用负载型双金属催化剂对四氯化碳进行还原脱氯研究,探究了温度、溶液初始pH值、催化剂投加量及不同钯载率对四氯化碳脱氯的影响;对比了不同催化剂包括纳米零价铁、纳米钯铁双金属和CeO_2负载型双金属Pd/Fe对四氯化碳的脱氯效果.实验结果表明负载型双金属催化剂在温度为40℃,溶液初始pH为6.5,催化剂投加量为0.4 g·L-1,钯载率为0.5%的条件下,对初始浓度为5 mg·L-1的四氯化碳的去除率高达99.88%.在相同的反应条件下,纳米零价铁和纳米钯铁双金属对四氯化碳的脱氯率分别为58.25%、87.94%.此外,对四氯化碳的脱氯机制进行了探讨.