秋、冬季渤海溶解N2O的分布和通量及其影响因素

通过2019年10月和12月对渤海海域进行的调查及样品采集,分析溶解N₂O的分布和影响因素,并估算其海-气交换通量。结果表明：秋季表层海水溶解N₂O浓度为(8.2±0.5)nmol/L,饱和度为(97.5±4.7)%;冬季浓度为(11.0±0.8)nmol/L,饱和度为(93.8±4.5)%。渤海表层海水溶解N₂O浓度呈现明显的季节性差异,冬季浓度高于秋季,且高值区均集中在黄河口以及莱州湾附近。秋季渤海溶解N₂O处于接近饱和状态,冬季则处于不饱和状态。温度、陆源淡水输入以及沉积物-水界面交换对渤海溶解N₂O的分布有重要影响。2019年10月和12月黄河向渤海输入N₂O的量分别约为4.2×10⁴ mol和1.1×10⁴ mol,是渤海N₂O的重要来源,而秋、冬季渤海底层的沉积物既可能是渤海水体N₂O的源,也可能是其汇。秋季和冬季渤海N₂O海-气交换通...     

Response of ammonia-oxidizing archaea to heavy metal contamination in freshwater sediment

It has been well-documented that the distribution of ammonia-oxidizing bacteria(AOB) and archaea(AOA) in soils can be affected by heavy metal contamination, whereas information about the impact of heavy metal on these ammonia-oxidizing microorganisms in freshwater sediment is still lacking. The present study explored the change of sediment ammonia-oxidizing microorganisms in a freshwater reservoir after being accidentally contaminated by industrial discharge containing high levels of metals. Bacterial amoA gene was found to be below the quantitative PCR detection and was not successfully amplified by conventional PCR. The number of archaeal amoA gene in reservoir sediments were 9.62 × 10~2–1.35 × 10~7 copies per gram dry sediment. AOA abundance continuously decreased, and AOA richness, diversity and community structure also considerably varied with time. Therefore, heavy metal pollution could have a profound impact on freshwater sediment AOA community. This work could expand our knowledge of the effect of heavy metal contamination on nitrification in natural ecosystems.     

四种典型大气环境下7B50铝合金的腐蚀行为研究

目的 研究湿热海洋、干热沙漠、寒冷乡村、暖温高原四种典型大气环境对7B50铝合金腐蚀行为的影响.方法 采用户外大气自然环境暴露试验,通过宏观腐蚀形貌分析、金相显微形貌分析、腐蚀深度分析和拉伸性能分析,对比研究7B50-T7751和7B50-T77511两种铝合金在不同大气环境中的腐蚀行为和规律.结果 暴露试验周期为3 a时,7B50-T7751铝合金在湿热海洋大气环境中腐蚀严重,局部最大腐蚀深度为166μm,抗拉强度和断后伸长率分别下降了5％和25％;在干热沙漠大气环境下腐蚀较重,局部最大腐蚀深度为44μm;在寒冷乡村、暖温高原大气环境下未见明显腐蚀.7B50-T77511铝合金在四种典型大气环境下均表现出明显腐蚀,局部最大腐蚀深度分别为141、80、42、29μm.结论 两种7B50铝合金在典型大气环境中表现出不同的耐蚀性,在微观上均表现为点蚀和晶间腐蚀的混合腐蚀,具有明显的晶间腐蚀和剥蚀倾向.两种铝合金暴露在相同大气环境中时,7B50-T7751板材耐蚀性较7B50-T77511型材略好.     

玉米—大豆轮作体系对黑土土壤固氮菌群落结构及其质量的影响

以大豆连作（CS）、玉米连作（CM）、玉米—大豆轮作（MS）、玉米—玉米—大豆（MMS）和玉米—大豆—大豆（MSS）为研究对象,利用荧光定量PCR和高通量测序分析种植制度对土壤固氮菌丰度和群落结构的影响。结果表明：轮作中土壤有机质（SOM）、全磷（TP）、有效氮（AN）和有效磷（AP）的含量显著高于连作;轮作固氮菌丰度显著高于CM,显著低于CS;MMS与MSS固氮菌多样性显著高于CM;轮作和连作土壤固氮菌群落结构差异明显,全氮（TN）是固氮菌群落结构变化的主要驱动因子,种植制度通过土壤化学性质间接影响固氮菌丰度和多样性。这说明,在吉林省西部半干旱区,MSS与MMS更有利于土壤固氮菌繁殖,可以从微生物学的角度为合理种植和氮素调控提供科学依据。     

纳米银与微塑料在模拟垃圾填埋柱中的共迁移特征

以模拟垃圾填埋柱和人工配制渗滤液,探讨了纳米银（AgNPs）和微塑料（MPs）在垃圾填埋场中的迁移行为.结果发现,无论是单体系还是二元体系,随着填埋时间增长,AgNPs和MPs颗粒在渗滤液中稳定性增强,在填埋场中迁移能力增大,可能导致填埋中晚期有更多的污染颗粒随渗滤液流出填埋场.当AgNPs和MPs共存时,相对于单体系促进了AgNPs的迁移而轻微地抑制了MPs的迁移.结合DLVO理论和胶体过滤理论分析,一方面是由于流动性更高的MPs可作为AgNPs的载体,同时与AgNPs竞争固相介质上的吸附位点,从而促进AgNPs的迁移.另一方面,共存的AgNPs降低了MPs颗粒的表面负电荷使其稳定性减弱,并通过预沉积在固相介质上提供额外的MPs沉积位点,从而抑制MPs的迁移.     

Improved atmospheric mercury simulation using updated gas-particle partition and organic aerosol concentrations

The gaseous or particulate forms of divalent mercury (Hg^II) significantly impact the spatial distribution of atmospheric mercury concentration and deposition flux (FLX). In the new nested-grid GEOS-Chem model, we try to modify the Hg^II gas-particle partitioning relationship with synchronous and hourly observations at four sites in China. Observations of gaseous oxidized Hg (GOM), particulate-bound Hg (PBM), and PM_2.5 were used to derive an empirical gas-particle partitioning coefficient as a function of temperature (T) and organic aerosol (OA) concentrations under different relative humidity (RH). Results showed that with increasing RH, the dominant process of Hg^II gas-particle partitioning changed from physical adsorption to chemical desorption. And the dominant factor of Hg^II gas-particle partitioning changed from T to OA concentrations. We thus improved the simulated OA concentration field by introducing intermediate-volatility and semi-volatile organic compounds (I/SVOCs) emission inventory into the model framework and refining the volatile distributions of I/SVOCs according to new filed tests in the recent literatures. Finally, normalized mean biases (NMBs) of monthly gaseous element mercury (GEM), GOM, PBM, WFLX were reduced from −33%–29%, 95%–300%, 64%–261%, 117%–122% to −13%–0%, −20%–80%, −31%–50%, −17%–23%. The improved model explains 69%–98% of the observed atmospheric Hg decrease during 2013–2020 and can serve as a useful tool to evaluate the effectiveness of the Minamata Convention on Mercury.     

Sulfur deposition simulations over China, Japan, and Korea: a model intercomparison study for abating sulfur emission

In response to increasing trends in sulfur deposition in Northeast Asia, three countries in the region (China, Japan, and Korea) agreed to devise abatement strategies. The concepts of critical loads and source?Creceptor (S?CR) relationships provide guidance for formulating such strategies. Based on the Long-range Transboundary Air Pollutants in Northeast Asia (LTP) project, this study analyzes sulfur deposition data in order to optimize acidic loads over the three countries. The three groups involved in this study carried out a full year (2002) of sulfur deposition modeling over the geographic region spanning the three countries, using three air quality models: MM5-CMAQ, MM5-RAQM, and RAMS-CADM, employed by Chinese, Japanese, and Korean modeling groups, respectively. Each model employed its own meteorological numerical model and model parameters. Only the emission rates for SO₂ and NO_x obtained from the LTP project were the common parameter used in the three models. Three models revealed some bias from dry to wet deposition, particularly the latter because of the bias in annual precipitation. This finding points to the need for further sensitivity tests of the wet removal rates in association with underlying cloud?Cprecipitation physics and parameterizations. Despite this bias, the annual total (dry plus wet) sulfur deposition predicted by the models were surprisingly very similar. The ensemble average annual total deposition was 7,203.6?±?370 kt S with a minimal mean fractional error (MFE) of 8.95?±?5.24?% and a pattern correlation (PC) of 0.89?C0.93 between the models. This exercise revealed that despite rather poor error scores in comparison with observations, these consistent total deposition values across the three models, based on LTP group's input data assumptions, suggest a plausible S?CR relationship that can be applied to the next task of designing cost-effective emission abatement strategies.     

多硫化钙与亚铁盐联用去除工业废水中的Cr(Ⅵ)

还原稳定化修复技术是当前重金属污染修复领域的主要技术,其中,重金属去除率和环境扰动是评价修复效果的重要指标.以不同pH重铬酸钾溶液模拟Cr(Ⅵ)污染水体,分别研究了多硫化钙、硫酸亚铁和二者联用对水体重金属Cr(Ⅵ)的还原稳定性,同时考察了环境因素对药剂联用的影响并探究各药剂对Cr(Ⅵ)的去除机理.结果表明:当多硫化钙与硫酸亚铁投加比例为1:2时,药剂联用对Cr(Ⅵ)和总Cr的去除效果均优于单独施加药剂时的去除效果且还原产物较稳定,对体系扰动作用相对较小;低pH和较高温度有利于联用药剂对Cr(Ⅵ)的去除,HCO3-、Cl-、Mn2+的加入有利于去除Cr(Ⅵ),Fe3+对 Cr(Ⅵ)去除表现为低浓度抑制、高浓度促进;经反应产物成分分析,多硫化钙与硫酸亚铁反应生成了具有催化效果的FeS,提高了修复效果.以上研究结果可为后期Cr(Ⅵ)污染水体的控制和修复提供参考.     

Biotransformations of Chlorophenols in River Sediments

Abstract

The accumulation of chlorophenols, including 2,4-dichlorophenol (2,4-DCP), 2,4,6-trichlorophenol (2,4,6-TCP) and pentachlorophenol (PCP), from river sediments from southern Taiwan were studied. Through simple or more exhaustive extractions, the results showed that 99% of the samples containing 2,4,6-TCP and PCP could be removed by simple extraction. the concentrations were found to range from non-detectable to 16.60 ngg¹ for 2,4,6-TCP and to 25.02 ngg¹ for PCP. Partition coefficients (K_p) were 0.71, 0.74 mlg¹ for 2,4,6-TCP, 1.35 and 1.41 mlg¹ for PCP. Biodegradation by DCP-adapted or unadapted anaerobes in sediment was carried out. During 21 days' incubation, the complete degradation time for 2,4,6-TCP in DCP-adapted anaerobic, unadapted anaerobic, and unadapted aerobic conditions were found to be 9, 10, 12 days for N3 sediment, and 8, 10, 11 days for N6 sediment, respectively; for PCP it was 19 days, without degradation, 14 days for N3 sediment, and 13, 17, 10 days for N6 sediment, respectively. the biodegradable products were identified as 2,3,4,5-tetrachlorophenol (2,3,4,5-TeCP), 3,4,5-TCP, 3,5-DCP, 3-MCP, phenol, methylphenol, and benzoate for PCP, and 2,4-DCP, 4-MCP, phenol, methylphenol, and benzoate for 2,4,6-TCP.     

镁粉着火敏感特性研究现状与分析

通过大量文献调研,从两个方面整理并分析了近年来关于镁粉着火敏感特性研究现状,即镁粉着火敏感特性参数和镁粉着火敏感特性防护技术研究,并在此基础上提出进一步的研究建议,为更好地预防镁粉爆炸事故及相关理论技术研究提供参考。