Multistep conversion of cresols by phenol hydroxylase and 2,3-dihydroxy-biphenyl 1,2-dioxygenase

A mulfistep conversion system composed of phenol hydroxylase （PHrND） and 2,3-dihydroxy-biphenyl 1,2-dioxygenase （BphCLA_4） was used to synthesize methylcatechols and semialdehydes from o- and m-cresol for the first time. Docking studies displayed by PyMOL predicted that cresols and methylcatechols could be theoretically transformed by this multistep conversion system~ High performance liquid chromatography mass spectrometry （HPLC-MS） analysis also indicated that the products formed from multistep conversion were the corresponding 3-methylcatechol, 4-methylcatechol, 2- hydroxy-3-methyl-6-oxohexa-2,4-dienoic acid （2- hydroxy-3-methyl-ODA） and 2-hydroxy-5-methyl-6-oxo- hexa-2,4-dienoic acid （2-hydroxy-5-methyl-ODA）. The optimal cell concentrations of the recombinant E. coli strain BL21 （DE3） expressing phenol hydroxylase （PHrND） and 2,3-dihydroxy-biphenyl 1,2-dioxygenase （BphCLA_4） and pH for the multistep conversion of o- and m-cresol were 4.0 （g-L-1 cell dry weight） and pH 8.0, respectively. For the first step conversion, the formation rate of 3- methylcatechol （0.29μmol·L-1·min-1·mg-1cell dry weight） from o-cresol was similarly with that ofmethylca- techols （0.28 μmol·L-1·min-1·mg-1 cell dry weight） from m-cresol by strain PHrND. For the second step conversion, strain BphCLA_4 showed higher formation rate （0.83 μmol·L-1·min-1·mg-1 cell dry weight） for 2-hydroxy-3-methyl- ODA and 2-hydroxy-5-methyl-ODA from m-cresol, which was 1.1-fold higher than that for 2-hydroxy-3-methyl- ODA （0.77 μmol·L-1·min-1·mg-1. mglcell dry weight） from ocresol. The present study suggested the potential application of the multistep conversion system for the production of chemical synthons and high-value products.     

论省级生态环境保护督察制度的完善

中共中央办公厅、国务院办公厅在2019年出台了《中央生态环境保护督察工作规定》,将省级生态环境保护督察制度法治化,并提出常态化实施的要求。作为一项新的改革举措,省级生态环境保护督察在实践中面临许多问题,照搬中央生态环境保护督察的形式难以取得明显实效,存在定位不准、措施不当、保障不力等问题。为此,要在明确督察的内涵和作用方式的基础上,从做好中央生态环境保护督察的补充和延伸的角度出发,提出省级生态环境保护督察的定位、工作程序要点和配套制度建设的需求,为下一步地方完善生态环境保护督察制度提供指导。     

基于三维荧光光谱技术解析不同微生物法净化黑臭水体的效果

应用曝气、菌剂+曝气、生物促生剂+曝气、菌剂+生物促生剂+曝气4种微生物技术净化黑臭水体,分别考察了进水中溶解性有机物(DOM)的特征和来源及出水中DOM的特征和效果,采用三维荧光(EEM)光谱技术与平行因子(PARAFAC)模型相结合的方式对进出水DOM进行了分析。结果表明,不同处理方式下进出水DOM的不同组分荧光峰强度变化存在较明显的差异,经过菌剂和生物促生剂联合处理之后,对类腐殖质等难降解物质削减效果最好。FI、HIX和BIX指数分析表明各处理水样中的DOM整体处于较强的自生源特征。利用主成分分析法(PCA)对影响黑臭水体DOM的主要因素及其贡献量研究发现:第1主成分表现为陆源类腐殖质和生物源类腐殖质共存的现象,对水体中DOM的贡献率为54.98%;第2主成分反映了以微生物代谢过程为代表的内源污染,对水体中DOM的贡献率为26.56%。因此,利用三维荧光分析能够较好的反映水中DOM的去除情况,易于实时在线监测,对黑臭水治理具有重要意义。     

农田土壤中铜的来源分析及控制阈值研究

农田土壤重金属污染直接危及到生态安全、食品安全和人体健康.从源头上控制农田土壤重金属污染是农业可持续发展和保障农产品质量安全的首要措施.本文采用物质流分析法与情景分析法,以水稻(双季稻、单季稻)、小麦-玉米、蔬菜(叶菜、根菜和果菜)的产地农田生态系统为研究对象,研究农田土壤中重金属铜的输入途径(大气沉降、磷肥、有机肥以及灌溉水)和输出途径(籽粒/可食部位、秸秆/残余物以及地表排水),并通过文献查阅和采样分析建立数据库,在平衡分析基础上为了保障100年土壤铜累积不超过设定的情景水平,当土壤铜背景值含量分别增加50％,100％和150％时,推导出磷肥、有机肥以及灌溉水的重金属含量安全阈值,磷肥中铜含量应控制在65～175 mg·kg-1范围内;畜禽粪肥中铜含量应控制在35～95 mg· kg-1范围内.灌溉水质标准应控制在40～70 μg·L-1范围内.这将为我国农产品产地安全管理和源头预防控制,保障我国农产品质量安全提供一定的技术指导作用.     

典型锌冶金区蔬菜重金属的生物可给性及健康风险评价

为了探究冶金区蔬菜重金属污染状况及对人体的危害,以葫芦岛锌冶炼厂周围为研究区域,对8种典型蔬菜中重金属含量进行分析,采用体外胃肠模拟实验,测算出蔬菜中重金属的生物可给性,并以此修正健康风险评价计算方法.结果表明,蔬菜中各重金属的生物可给性在模拟胃阶段表现为:Cd(67.67%)Pb(50.70%)Cu(44.69%)Hg(3.09%);在模拟肠阶段表现为:Pb(48.90%)Cd(40.66%)Cu(32.88%)Hg(13.12%).由生物可给性校正后,人群通过饮食蔬菜途径摄入重金属的目标危险系数(THQ)顺序依次为:CdPbCuHg.基于胃肠阶段生物可给性计算的重金属单元素的目标危险系数(THQ)及多种重金属复合的目标危险系数(TTHQ)均小于1,但基于胃阶段生物可给性的Cd目标危险系数(THQ)仍然超过1,表明锌厂周围人群通过饮食蔬菜途径摄入重金属存在健康风险.成人的4种单元素THQ值和TTHQ值均高于儿童,说明成人通过饮食蔬菜途径摄入重金属的健康风险高于儿童.     

Gamma irradiation-induced decomposition of sulfamethoxazole in aqueous solution: the influence of additives,biological inhibitory,and degradation mechanisms

Sulfamethoxazole (SMX) was decomposed by using gamma irradiation in the presence of different additives such as NO₃ ⁻, NO₂ ⁻, Cr(VI), 2-propanol, and tert-butanol. The results demonstrated that NO₃ ⁻, NO₂ ⁻, 2-propanol, and tert-butanol inhibited SMX radiolytic removal. However, there existed a synergetic effect for radiolytic removal of the mixture containing SMX and Cr(VI). At an absorbed dose of 150 Gy, the removal percentages of SMX and Cr(VI) in the mixture were 73.5 and 84.6%, respectively, which was higher than the removal percentages of 70.6 and 4.1% for the single component of SMX and Cr(VI). This provides us an insight into treating the combined pollution in micro-polluted water. The SMX radiolytic removal followed a pseudo first-order reaction kinetic model, and the rate constant ratios of ·OH, e_aq ⁻, and H· towards SMX radiolysis were 10.4:1:2.9. In addition, 24-h bio-inhibitory to the macroalgae of SMX solution during gamma irradiation reached the maximum of 0.85 at an adsorbed dose of 100 Gy, then gradually decreased with the increasing adsorbed dose. Based on LC-MS analysis and quantum chemical calculation, the degradation intermediates were determined and concluded that SMX radiolytic removal was mainly via ·OH radical attack and direct decomposition of SMX molecule by gamma ray.

     

美国加州空气质量政府管理模式及对中国的启示

中国城市空气污染呈区域化和恶化趋势,亟需突破当前空气质量管理模式的制约.从管理体制和管理内容两方面对美国空气质量政府管理模式的先进经验进行了分析,并与北京市空气质量管理模式进行了初步比较,得出中国空气质量政府管理模式缺乏外部性的考虑；政府部门内部机构按照行政管理过程划分,导致管理成本偏高；决策机制与执行机制未分离,影响行政效率；对污染源的管理不专业；缺乏信息公开和公众参与等问题.建议成立空气质量管理分局,对固定源实行排污许可证管理,对移动源实行统一综合管理,细化面源的管理,建立空气质量管理信息公开平台.     

MOA-based linear and nonlinear QSAR models for predicting the toxicity of organic chemicals to Vibrio fischeri

Environmental Science and Pollution Research - Risk assessment of pollutants to humans and ecosystems requires much toxicological data. However, experimental testing of compounds expends a large...     

Luoyang Dual Spatial Criterion Ecological City Construction

The construction of an ecological city has two foundational platforms： the small platform, namely urban district or simply called as ＂city ecosystem＂; and the big platform, namely around city district in certain region scope or also referred to as ＂city-region ecosystem＂. The construction of an ecological city must be launched in the dual spatial criteria： in city （urban district） criterion--optimizing the city ecosystem; in city-region （city territory） criterion-optimizing the city-region ecosystem. Luoyang has the bright characteristic and the typical image within cities Of China, and even in the world. The construction of an ecological city in dual spatial criteria--the city and the cityregion has the vital significance to urbanization advancement and sustainable development in Luoyang. In city-region criterion, the primary mission of Luoyang＇s ecological city construction is to create a fine ecological environment platform in its city territory. In city criterion, the basic duty of Luoyang＇s ecologic city construction is to enhance the ecological capacity and benefit of the central city.