滇池沉积物氮内源负荷特征及影响因素

研究了滇池沉积物间隙水氮浓度垂向分布特征,根据Fick扩散定律定量估算了沉积物-水界面氮扩散通量,并探讨了其影响因素.结果表明:滇池沉积物间隙水溶解性总氮(DTN)主要以氨态氮(NH4+-N)形式存在,占其总量的72.30%,其浓度随深度增加而升高;其次为溶解性有机氮(DON),占其总量的24.59%,其浓度随深度的增加先升高后降低,最后趋于稳定;硝态氮(NO3--N)所占比例较低,浓度随深度的增加而降低.滇池沉积物-水界面NH4+-N扩散通量分布范围为12.73~59.74mg/(m2·d)[均值30.18mg/(m2·d)],全湖年均氨氮释放量为3305.04t,其中草海、外海北部、东北部及南部湖区扩散通量较大,达35mg/(m2·d),全湖呈由北向南逐渐降低的空间分布特征;全湖年均DON释放量为1147.55t,其全湖分布特征与氨氮一致;NO3--N扩散通量分布范围为-2.70~0.27mg/(m2·d)[均值-0.50mg/(m2·d)],总体表现为由上覆水向沉积物扩散.与我国其他湖泊相比,滇池具有较大沉积物氮内负荷,其沉积物-水界面NH4+-N扩散通量较高,对湖泊水体氨氮浓度贡献较大,且其与沉积物总氮、有机质、可交换态氮和可交换态氨氮含量呈显著正相关,即滇池沉积物NH4+-N释放主要受其可交换态氮,特别是可交换态中氨氮含量影响;同时,滇池沉积物DON潜在释放风险也较大,且与沉积物C/N有关.     

基于Bow-Tie技术的民用机场安全风险分析应用研究

民用运输机场具有运行环境复杂、事故成因复杂、驻场单位众多等特点,其事故成因更具有动态性、隐蔽性、综合性和因果连带性。因此,机场的日常运行安全风险分析一般需要借助多种工具才能完成。本文系统的介绍了一种实用的风险分析方法-Bow-tie风险技术,Bow-tie是一种风险分析和风险管理的工具,通过识别和评估风险、分析风险因素、设置风险屏障、采取风险控制和(减缓)恢复措施,有效预防事故发生。该方法可以对危害事件发生的原因、后果、屏障建立是否充足提供一个可视化的评估。本文就Bow-tie技术在民用机场安全风险中的具体实施步骤进行了描述,最后给出了其在民用机场风险分析中应用的一个实例,并就其可行性和实际应用进行了系统的研究。Bow-tie风险技术是集故障树、事件树和圆葱图理论相结合的系统风险分析及量化技术,对组织缺陷以及人为失误占主导因素的民用机场运行安全风险分析,具有较高的应用价值。     

基于连续小波变换、SHAP和XGBoost的土壤有机质含量高光谱反演

针对土壤有机质含量高光谱反演中存在的光谱有效信号薄弱和光谱信息冗余问题,提出结合连续小波变换、SHAP和XGBoost的土壤有机质含量高光谱反演框架.以北京市延庆区和房山区永久基本农田土壤为研究对象,首先,基于连续小波变换处理的土壤光谱反射率数据构建初始XGBoost模型;然后,利用SHAP方法分析模型中各波段的贡献度以筛选特征波段;最后,基于特征波段重新构建和优化XGBoost模型,实现土壤有机质含量高光谱反演.发现连续小波变换尺度为25时,利用SHAP方法选取的40个特征波段构建的XGBoost模型准确性最高,有机质含量反演值和实测值之间的R²为0.80,RMSE为3.60g·kg^-1;随着连续小波变换尺度的增大,R2呈现先升高后降低的趋势,25尺度下的R2比21尺度的高0.37;SHAP方法选取的特征波段比Pearson相关分析法少682个,RMSE低0.69 g·kg^-1;XGBoost模型的R2分别比随机森林和支持向量机模型高4%和8%.验证了结合连续小波变换、SHAP和XGBoost在土壤有机质含量高光谱反演...     

铁炭微电解-C1O2催化氧化处理酮康唑废水

采用铁炭微电解-C1O2催化氧化串联工艺对以甲苯、溴化钠、三乙胺、苯甲酸钠、米唑、二甲基亚酚、酮康唑母液等物质为主的酮康唑废水进行预处理后,COD去除率达到75%以上.经过预处理的废水再按一定比例与冲洗废水混合,经PAC-SBR生化处理后,可使出水的COD、色度等指标达到<污水综合排放标准>(GB8978-1996)中的一级标准.     

胞外聚合物对活性污泥吸附及再生的影响研究

通过研究胞外聚合物 (EPS)对活性污泥吸附及再生的影响 ,探讨吸附、再生机理。吸附试验表明 ,EPS与污泥吸附能力显著相关 ,随着污泥负荷的降低 ,EPS增加 ,污泥的吸附能力提高 ;并且有机物种类对污泥的吸附性能有显著影响 ,研究表明吸附机理主要是生物絮凝作用。此外 ,再生试验结果表明 ,再生能增加中负荷 (Ns) =0 3～ 0 5kgBOD5/kgMLSS·d污泥的吸附能力 ,但不能改变高负荷 (Ns) =2～ 3kgBOD5/kgMLSS·d污泥的吸附能力。其作用机理是再生过程可迫使中负荷污泥进入内源代谢期 ,使污泥中的EPS增加 ,絮凝活性增加 ,吸附能力提高 ,而高负荷污泥再生后EPS则无变化。同时 ,再生过程将使污泥的脱氢酶、OUR降低 ,代谢活性降低。对于高负荷污泥的再生是无效的。     

Frontier science and challenges on offshore carbon storage

● The main direct seal up carbon options and challenges are reviewed. ● Ocean-based CO₂ replacement for CH₄/oil exploitation is presented. ● Scale-advantage of offshore CCS hub is discussed. Carbon capture and storage (CCS) technology is an imperative, strategic, and constitutive method to considerably reduce anthropogenic CO₂ emissions and alleviate climate change issues. The ocean is the largest active carbon bank and an essential energy source on the Earth’s surface. Compared to oceanic nature-based carbon dioxide removal (CDR), carbon capture from point sources with ocean storage is more appropriate for solving short-term climate change problems. This review focuses on the recent state-of-the-art developments in offshore carbon storage. It first discusses the current status and development prospects of CCS, associated with the challenges and uncertainties of oceanic nature-based CDR. The second section outlines the mechanisms, sites, advantages, and ecologic hazards of direct offshore CO₂ injection. The third section emphasizes the mechanisms, schemes, influencing factors, and recovery efficiency of ocean-based CO₂-CH₄ replacement and CO₂-enhanced oil recovery are reviewed. In addition, this review discusses the economic aspects of offshore CCS and the preponderance of offshore CCS hubs. Finally, the upsides, limitations, and prospects for further investigation of offshore CO₂ storage are presented.     

微囊藻毒素-LR多克隆抗体的制备

通过对新西兰大白兔免疫自制的微囊藻毒素-LR(Microcystin-LR,MC-LR)完全抗原BSA-MC-LR,获得了质量较好的抗MC-LR的多克隆抗体,间接ELISA表明抗体的效价能达到1.5×10⁵;固定包被抗原OVA-MC-LR,采用间接竞争ELISA测定水体中的微囊藻毒素,标准曲线表明对水样中MC-LR的检测下限为10ng/L,线性区间为30ng/L·3μg/L,能满足对饮用水和地表水中MC-LR的检测要求.     

共代谢对难降解有机物生物降解性能的影响

利用瓦呼仪测试法测试了呋喃等6种难降解有机物在单一基质和与苯酚共基质的条件下生物降解性能,研究共代谢对难降解有机物生物降解性能的影响。研究表明,共代谢对呋喃、喹啉、吲哚生物降解性能有明显提高,吡啶、联苯、三联苯在低浓度时,生物降解性能有所改善。     

桂林市桃花江流域水污染现状分析及对策

分析了桂林市桃花江流域中存在的污染问题和产生这些问题的原因,探讨了解决这些问题的对策。     

Characteristics of PM2.5 pollution in Beijing after the improvement of air quality

Following the implementation of the strictest clean air policies to date in Beijing, the physicochemical characteristics and sources of PM_2.5 have changed over the past few years. To improve pollution reduction policies and subsequent air quality further, it is necessary to explore the changes in PM_2.5 over time. In this study, over one year (2017–2018) field study based on filter sampling (TH-150C; Wuhan Tianhong, China) was conducted in Fengtai District, Beijing, revealed that the annual average PM_2.5 concentration (64.8 ± 43.1 μg/m³) was significantly lower than in previous years and the highest PM_2.5 concentration occurred in spring (84.4 ± 59.9 μg/m³). Secondary nitrate was the largest source and accounted for 25.7% of the measured PM_2.5. Vehicular emission, the second largest source (17.6%), deserves more attention when considering the increase in the number of motor vehicles and its contribution to gaseous pollutants. In addition, the contribution from coal combustion to PM_2.5 decreased significantly. During weekends, the contribution from EC and NO₃^? increased whereas the contributions from SO₄^2?, OM, and trace elements decreased, compared with weekdays. During the period of residential heating, PM_2.5 mass decreased by 23.1%, compared with non-heating period, while the contributions from coal combustion and vehicular emission, and related species increased. With the aggravation of pollution, the contribution of vehicular emission and secondary sulfate increased and then decreased, while the contribution of NO₃^? and secondary nitrate continued to increase, and accounted for 34.0% and 57.5% of the PM_2.5 during the heavily polluted days, respectively.