京津冀中南部污染气象贡献的时空变化特征

基于环境气象评估指数（EMI，environmental meteorology index），以石家庄、邢台、邯郸、衡水四个京津冀中南部重点城市为研究对象，对2013~2018年的气象条件变化时空分布特征进行分析.结果显示：EMI指数与经过去趋势处理的PM_2.5浓度的相关系数达0.88，说明EMI指数具有较好的可靠性，能够可靠性地应用于大气环境评价和重污染天气过程评估业务；基于气象条件对PM_2.5浓度贡献的定量分析方法，计算得到2013~2018年月度气象条件对PM_2.5浓度变化的贡献率，定量分析不同月份的气象条件变化，可有效评价不同污染程度月份的气象条件影响.此外，该定量方法在重大活动期间气象条件和减排效果评估中得到有效应用；从冬季气象定量贡献的空间分布来看，在京津冀中南部的山前地区形成EMI正距平百分比高值区，除人为排放较高外，恶劣的气象条件是京津冀中南部颗粒物污染严重的重要原因.

Effect of NO3- on spectral characteristic of the complexation of DOM and Cu2+ from secondary effluent

The effects of nitrate on the spectral characteristics and complexation ability of DOM with Cu²⁺ in the secondary effluent of municipal wastewater were investigated by using three-dimensional fluorescence and UV spectrophotometry. The fluorescence peak representing the protein-like (tryptophan-like) produced by complexation of DOM and Cu²⁺ disappeared with the increase of NO₃^- concentration, and the right side of the UV absorption peak occurred red-shift. The concentration of NO₃^- was significantly positively correlated with the values of HIX, α₃₀₀, α₂₅₀/α₃₆₅, E₃/E₄ and UV₂₅₃/UV₂₀₃ after complexation of DOM with Cu²⁺, while negatively correlated with BIX (r with -0.958~-0.719). It had an exponential increase with S_240-400 (R² with 0.9678~0.9952) and an exponential decrease with S_275-295 (R² with 0.9965~0.9978), but had little effect on the values of FI, α₃₅₀, α₃₅₅ and S_350-400. The conditional stability constant lgK of ultraviolet humus-like, visible humus-like and high excitation wavelength tryptophan-like in the secondary effluent of DOM with Cu²⁺ were 2.08~2.46L/mmol, 1.84~2.51L/mmol and 2.27~2.57L/mmol, respectively; and the proportion of coordination fluorescent functional groups were 19.5%~36.5%, 22.5%~33.3% and 24.4%~29.2%, respectively. In summary, there was not significant difference in the intensity of the complexation reaction between Cu²⁺ and humus-like or protein-like from DOM of the secondary effluent. When the NO₃^- concentration in the samples was different, there were some uncertainties in expressing the content of DOM and molecular properties with partial fluorescence (HIX) and ultraviolet parameters (α₃₀₀, α₂₅₀/α₃₆₅, E₃/E₄, S_240-400 and S_275-295).