中国典型背景站夏季VOCs污染特征及来源解析

选取庞泉沟、神农架、武夷山和长岛4个代表性大气背景站,使用SUMMA罐采样及GC-FID/MS方法分析了4个背景站夏季环境空气中57种挥发性有机污染物浓度水平、物种组成以及日变化特征,并利用PMF模型对背景站VOCs进行来源解析和臭氧生成潜势(OFP)分析.结果 表明,采样期间庞泉沟、神农架、武夷山和长岛的VOCs平均...     

混合金属氧化物/碳复合材料的制备及其对Pb(Ⅱ)的吸附性能

由金属离子及其类似物可控合成的层状双金属氢氧化物具有丰富的层间离子和表面官能团,因而在吸附方面得到了广泛研究,但吸附-脱附应用方式会对环境造成二次污染.将吸附刚果红的层状双金属氢氧化物通过煅烧碳化制备混合金属氧化物/碳复合材料,详细研究了对水溶液中重金属离子Pb(Ⅱ)的吸附性能.结果表明,混合金属氧化物/碳复合材料对Pb(Ⅱ)具有较快的吸附速率和较高的吸附容量.30 min内吸附量即可达到150 mg·g^-1以上,同时,其吸附量随层状双金属氢氧化物中引入Mg²⁺含量的增加而增加,最大达到368 mg·g^-1.混合金属氧化物/碳复合材料对Pb(Ⅱ)的去除机制主要是表面诱导生成难溶物Pb₃(CO3)₂(OH)₂.研究结果为混合金属氧化物/碳复合材料对含铅土壤的修复奠定了应用基础.     

镉污染大田条件下不同品种水稻镉积累的特征及影响因素

选取适合当地种植的8个水稻品种为试验对象,开展大田试验,比较不同品种水稻对重金属Cd的积累、吸收和转运特征,筛选出适合当地种植的Cd低累积水稻品种,并分析水稻低累积程度及稳定性影响因素.结果表明:(1)根据综合积累指数(P_N)评价方法筛选出对Cd综合积累能力低的水稻品种有:川优3203、川优6203、德粳6号和沈优17.(2)综合考虑稻米Cd含量和产量,适合在该地区种植的水稻品种为川优3203和川优6203,既能安全保障稻米Cd含量,又能保证水稻高产.(3)川优3203和川优6203在不同p H和不同总镉范围内稻米中Cd含量均显著低于其他品种,且在不同土壤条件下表现得很稳定.(4)水稻品种的差异对水稻的稻米富集能力有较大的影响,而对水稻茎叶向水稻稻米的转运能力的影响较小;川优3203和川优6203的低富集系数,加之其较低的转运,最终呈现出稻米较低的镉富集能力.(5)相关性分析发现,稻米Cd含量受水稻富集系数影响最大,受根际土壤总Cd含量影响最小.     

Cu2+强化UV活化过氧乙酸降解水中的双氯芬酸

研究了Cu²⁺强化UV活化过氧乙酸（Cu²⁺/UV/PAA）对水中双氯芬酸（DCF）的降解,考察了pH值、PAA投加量、Cu²⁺投加量、无机阴离子（Cl^-、SO₄^2-、NO₃^-和CO₃^2-）和溶解有机物（DOM）对DCF去除的影响;探讨了DCF在该体系中的降解产物和转化机理.结果表明：UV和Cu²⁺都能活化PAA产生活性自由基促进DCF降解.DCF在Cu²⁺/UV/PAA中的降解遵循准一级动力学,其降解可能归因于直接光解、HO^·氧化和CH₃COO^·、CH₃COOO^·等其它自由基氧化.在pH=3~11范围内,DCF降解的最佳pH=8.5.DCF的降解效率随着PAA投加量的增大而逐渐增高,过量的PAA能与DCF竞争HO^·.Cu²⁺用量的提高也能促进DCF的去除,但是过量的Cu²⁺可生成Cu（OH）₂导致其催化能力下降.由于NO₃^-在UV照射下可以产生HO^·,其对DCF降解有促进作用,且NO₃^-浓度越高,促进作用越明显.不同浓度的Cl^-、SO₄^2-、CO₃^2-和DOM对DCF降解影响较小.在Cu²⁺/UV/PAA降解DCF的过程中,共检测出13种降解产物.根据这些降解产物,提出了DCF可能的转化机理,包括8种不同的反应路径.     

2020年成都市典型臭氧污染过程特征及敏感性

2020年4月24日至5月6日成都市臭氧(O3)和细颗粒物(PM2.5)复合污染过程期间,在成都市城区开展大气臭氧及其前体物(NO,、VOCs)和气象参数观测实验,基于观测数据采用OBM模型对市区臭氧敏感性和主控因子进行识别,并采用PMF模型对关键VOCs物种进行来源解析.结果表明,臭氧超标日各污染物浓度均有所上升,V...     

An unusual high ozone event over the North and Northeast China during the record-breaking summer in 2018

Under the background of global warming, the summer temperature of the North and Northeast China (NNEC) has significantly increased since 2017, which was accompanied by the aggravated ozone (O₃) pollution. In 2018, the NNEC experienced a record-breaking summer of the past 40 years. Influenced by the abnormal high temperatures, a regional ozone event occurred on 2-3 August, over 63% of 79 selected cities in the NNEC were exposed to O₃ pollution, and the maximum value of MDA8 O₃ reached 268 μg/m³. Observations indicated that ozone concentrations agree well with the maximum temperature at 2 meters (MT2M) over NNEC with a correlation coefficient of 0.69. During the pollution episode, strong downdraft in the local high (35°N-42.5°N, 112.5°E-132.5°E; LH) over the NNEC created the favourable meteorological conditions for O₃ formation. By analyzing the horizontal wind and wave activity fluxes (WAFs) at 200 hPa, we found that the LH formation was resulted from the Rossby wave propagation from upstream along the mid-latitude Asian jet. The split polar vortex intrusion further strengthened the amplitude of the Rossby wave and reinforced the LH. Moreover, a secondary circulation between Typhoon Jongdari and the LH contributed to the enhanced LH with strong subsidence. On the other hand, the stratospheric intrusions under the deep subsidence also contributed to the enhanced surface O₃. In this study, the deep-seated meteorological dynamical mechanisms contributing to the abnormal high temperatures were investigated, which can lead to a better understanding of the regional O₃ pollution over NNEC under the global-warming background.     

Marine aquaculture regulates dissimilatory nitrate reduction processes in a typical semi-enclosed bay of southeastern China

Marine aquaculture in semi-enclosed bays can significantly influence nutrient cycling in coastal ecosystems. However, the impact of marine aquaculture on the dynamics of dissimilatory nitrate reduction processes (DNRPs) and the fate of reactive nitrogen remain poorly understood. In this study, the rates of DNRPs and the abundances of related functional genes were investigated in aquaculture and non-aquaculture areas. The results showed that marine aquaculture significantly increased the denitrification (DNF) and dissimilatory nitrate reduction to ammonium (DNRA) rates and decreased the rate of anaerobic ammonium oxidation (ANA), as compared with non-aquaculture sites. DNF was the dominant pathway contributing to the total nitrate reduction, and its contribution to the total nitrate reduction significantly increased from 66.72% at non-aquaculture sites to 78.50% at aquaculture sites. Marine aquaculture can significantly affect the physicochemical characteristics of sediment and the abundances of related functional genes, leading to variations in the nitrate reduction rates. Although nitrate removal rates increased in the marine aquaculture area, ammonification rates and the nitrogen retention index in the aquaculture areas were 2.19 and 1.24 times, respectively, higher than those at non-aquaculture sites. Net reactive nitrogen retention exceeded nitrogen removal in the aquaculture area, and the retained reactive nitrogen could diffuse with the tidal current to the entire bay, thereby aggravating N pollution in the entire study area. These results show that marine aquaculture is the dominant source of nitrogen pollution in semi-enclosed bays. This study can provide insights into nitrogen pollution control in semi-enclosed bays with well-developed marine aquaculture.     

控制回路的多维度性能评估方法研究

为评价炼化装置中各控制回路的性能,基于控制回路关键品质指标要求,采用控制回路的设定值、输出值、测量值、控制模式等过程参数设计了准确性指标、稳定性指标及快速性指标等性能评估指标。辅助技术人员在线进行控制回路性能评估,识别性能较差的控制回路,诊断异常原因并进行优化,提高装置的自动化水平。     

普光气田集输管网系统安全运行实践

针对普光气田地理环境现状,从地质灾害、焊口缺陷、管道腐蚀等方面对集输管网安全隐患进行了分析,结合现有风险防控措施,对下一步工作进行了展望,提出应加强硫化氢泄漏扩散机理研究及环焊缝失效机理研究。     

LNG全容罐安全阀尾管设置研究

针对LNG全容罐罐顶安全阀尾管排放气被点燃后产生的喷射火热辐射,可能导致全容罐开裂、坍塌等事故情况,分析确定安全阀尾管高度及排放方向是火灾热辐射影响范围的重要因素,通过采用DNV PHAST软件进行16×10~4 m~3全容罐罐顶安全阀释放可燃气云扩散影响及喷射火热辐射影响模拟计算,确定安全阀尾管高度15 m,垂直排放时能够满足相关安全要求,为LNG全容罐安全阀尾管高度优化设计提供了一种模拟计算方法。