水源地土壤环境保护优先区划分方法与实例研究

本研究综合考虑水源地沿岸土壤环境质量、水体污染现状、环境脆弱性和污染源压力这4个方面,探索建立了河流型水源地土壤环境保护优先区划分的技术方法,并以广东省佛山市顺德水道作为实证案例,结合当地自然-社会-经济条件,选取土壤污染程度、沉积物污染程度、土壤特性、地下水敏感性、植被覆盖度、污染源类型、污染源分布作为评价因子,构建了水源地土壤环境保护优先区分等定级评价指标体系.将实地采样分析与遥感影像解译相结合获取数据,采用层次分析法(AHP)确定指标权重,通过加权求和与图层叠加完成空间分析与制图,编制了顺德水道土壤环境保护优先区分级图.其中,污染区、风险区、安全区的面积分别占区域总面积的6.37%、60.90%、32.73%,且污染区和风险区集中在河道两岸的乐从镇、龙江镇和勒流街道,分布于该区域的家具制造、塑料建材、纺织服装等产业的长期发展,以及水产养殖等农业活动应是主要的污染来源,并据此提出了有针对性的差异性管控措施.本研究对水源地土壤环境保护和可持续开发利用具有重要指导意义.     

环境模型中敏感性分析方法评述

模型本身及其参数的不确定性使其模拟结果的可靠性备受争议,科学地认识模型的不确定性并对其进行定量的评价一直是环境模型研究的前沿,也是环境模型构建和应用过程中不可缺少的环节.通过敏感性分析,研究模型输入参数的变化对模型输出结果的影响程度,有助于了解并简化模型结构、提高参数率定效率、增进模型精度并增加模型应用的可靠性.本研究总结了敏感性分析在环境模型中的作用,并对常见的敏感性分析方法的原理、应用范围和优缺点进行了综述.最后,阐述了敏感性分析在环境模型模拟决策中应用的现状和未来研究方向.     

Kinetics of nitrobenzene degradation coupled to indigenous microorganism dissimilatory iron reduction stimulated by emulsified vegetable oil

Widespread contamination by nitrobenzene(NB) in sediments and groundwater requires better understanding of the biogeochemical removal process of the pollutant. NB degradation, coupled with dissimilatory iron reduction, is one of the most efficient pollutant removal methods. However, research on NB degradation coupled to indigenous microorganism dissimilatory iron reduction stimulated by electron donors is still experimental. A model for remediation in an actual polluted site does not currently exist.Therefore, in this study, the dynamics was derived from the Michaelis–Menten model(when the mass ratio of emulsified vegetable oil and NB reached the critical value 91:1). The effect of SO_4~(2-), NO_3~-, Ca~(2+)/Mg~(2+), and the grain size of aquifer media on the dynamics were studied, and the NB degradation dynamic model was then modified based on the most significant factors. Utilizing the model, the remediation time could be calculated in a contaminated site.     

甲烷催化还原NOx中Co基/分子筛催化剂的助剂和载体优化

采用共浸渍法制备了系列Co基/分子筛催化剂,在固定床催化反应器中考察了不同催化剂在甲烷催化还原NO_x中的催化行为,优化了Co基/分子筛催化剂的助剂和载体,并通过催化表征手段阐明了其构效关系.结果表明,Fe和SAPO-34分别作为优化助剂和载体制备得到的Co-Fe/SAPO-34催化剂具有最高的催化活性,在450℃时,NO_x的最大转化率可以达到52.7%.CO_2对Co-Fe/分子筛催化剂活性无明显抑制作用,H_2O对催化剂的活性抑制是可逆的,SO_2对催化剂活性抑制作用明显.Co-Fe/SAPO-34催化剂表面钴物种以CoO和Co(OH)_2为主,Co-Fe/ZSM-5催化剂表面钴物种则以Co_3O_4和Co(OH)_2为主,Co-Fe/Beta催化剂则可能以CoO、Co Al2O_4和Co_3O_4为主.各Co-Fe/分子筛催化剂表面Fe~(2+)/Fe~(3+)含量比依次为Co-Fe/ZSM-5(3.98)Co-Fe/SAPO-34(0.52)Co-Fe/Beta(0.43).活性组分钴物种的形态和合适的Fe~(2+)/Fe~(3+)含量比对Co-Fe/分子筛催化剂上甲烷催化还原NO_x至关重要.Co-Fe/分子筛催化剂上CH_4-SCR反应机制为:NO在Br?nsted酸位上吸附氧化成NO~+,同时CH_4在Br?nsted酸位上吸附活化成—C=O和—COO等活性物种,生成的NO~+在Co2+和Fe~(3+)等催化活性位上转化成硝酸盐等中间产物,中间产物硝酸盐与活化物种(—C=O和—COO)反应生成N_2和CO_2.     

Interfacial-engineered CoTiO3-based composite for photocatalytic applications: a review

Environmental Chemistry Letters - Photocatalysis is a green chemical process that could partly solve energy and pollution issues. Catalysts such as cobalt titanate, CoTiO3, have intrigued...     

海口市臭氧污染及气象条件特征

近年来,臭氧已成为许多城市环境空气的主要污染物之一。笔者分析了2020年海口市5个不同方位代表性监测站点逐小时空气质量监测数据及对应站点的气象要素监测数据。研究结果表明:海口市2020年环境空气污染程度为三级以上的天数有11d,其首要污染物均为臭氧。臭氧浓度高值时段主要出现在10-12月。浓度最大值主要出现在每日14:00-17:00,最小值出现在每日05:00-08:00。气象要素日均值与臭氧浓度相关性大小依次为最高温度＞平均温度＞相对湿度＞降水量＞日照时数＞风速。台风外围下沉气流和东北气流的共同影响是导致海口市臭氧浓度超标的主要因素,下沉气流更有利于低层大气中臭氧的堆积,同时在东北气流影响下,上游区域污染物的传输也会导致海口市臭氧浓度增加。     

Formation of halonitromethanes from methylamine in the presence of bromide during UV/Cl2 disinfection

The UV/Cl₂ process is commonly used to achieve a multiple-barrier disinfection and maintain residuals. The study chose methylamine as a precursor to study the formation of high-toxic halonitromethanes (HNMs) in the presence of bromide ions (Br⁻) during UV/Cl₂ disinfection. The maximum yield of HNMs increased first and then decreased with increasing concentration of Br⁻. An excessively high concentration of Br⁻ induced the maximum yield of HNMs in advance. The maximum bromine incorporation factor (BIF) increased, while the maximum bromine utilization factor (BUF) decreased with the increase of Br⁻ concentration. The maximum yield of HNMs decreased as pH value increased from 6.0 to 8.0 due to the deprotonation process. The BUF value remained relatively higher under an acidic condition, while pH value had no evident influence on the BIF value. The maximum yield of HNMs and value of BUF maximized at a Cl₂:Br⁻ ratio of 12.5, whereas the BIF value remained relatively higher at low Cl₂:Br⁻ ratios (2.5 and 5). The amino group in methylamine was first halogenated, and then released into solution as inorganic nitrogen by the rupture of C-N bond or transformed to nitro group by oxidation and elimination pathways. The maximum yield of HNMs in real waters was higher than that in pure water due to the high content of dissolved organic carbon. Two real waters were sampled to verify the law of HNMs formation. This study helps to understand the HNMs formation (especially brominated species) when the UV/Cl₂ process is adopted as a disinfection technique.     

汽车火灾的原因分析及预防

汽车在使用中,由于违反操作规程或对易燃品的管理不严,以及交通事故中发生撞车、翻车等,都会发生火灾.汽车火灾与其它车辆事故一样,都会带来严重损失和后果,因此,在预防车辆事故中应高度重视汽车火灾的预防.     

企业安全文化评价模型的建立

应用模糊数学理论,结合安全检查表,对企业安全文化进行模糊综合评价,得出企业安全文化等级.确定评价因素的权重时,采用了定性与定量相结合的层次分析法,使权重的赋值更加科学合理,较好地反映了各因素对企业安全文化现状的重要程度.     

北京科教园区绿地土壤中多环芳烃的残留特征与潜在风险

科教园区绿地土壤环境质量关系到在其中学习、工作和生活的学生和教职员工的身体健康.本研究对多环芳烃(PAHs)在科教园区绿地土壤中的累积特征、主要来源、潜在健康风险及其与土壤有机质(SOM)的相关关系进行了分析.共采集了北京市城区20所学校和研究机构中的绿地土壤,使用自动索氏-固相萃取-GC/MS联用技术分析了16种PAHs在其中的残留水平.结果表明16种PAHs总浓度范围为194～6 988μg.kg-1,平均值为1 637μg.kg-1.中、高环的PAHs(4～6环)占到了总PAHs浓度的85%.源解析结果显示其主要来源是科教园区内部冬季供暖和食物供应过程中所燃烧的煤.聚类分析显示NAP与其余15种PAHs组份在来源方式上存在明显的区别.除NAP以外,其余15种PAHs含量与土壤有机质之间没有相关关系,推测这15种PAHs组份主要来源于近距离源的一次沉降.北京市科教园区绿地土壤PAHs对生活在其周围的人群产生的终生致癌风险较小,但其间接影响不容忽视.