青藏高原城镇化及其动力机制分析

青藏高原由于地处高寒偏远 ,社会经济长期处于落后封闭状态 ,社会经济基础薄弱 ,城镇发展缓慢 ,至1952年青藏高原全境解放时其城镇发展水平很低。其后四十多年来 ,青藏高原城镇得到了很大发展 ,城镇化进程加快。由于自然与人文环境具独特性 ,青藏高原城镇发展和城镇化进程独具特色。高原城镇发展表现为总体落后 ,局部发展加速。城镇化现状特征表现为城镇数量少 ,规模小 ,城镇化水平低 ;城镇发展地域差异明显 ,空间上集中在河谷地区 ,呈沿交通线分布格局 ;城镇经济发展水平较低 ,设施落后 ,职能单一 ,缺乏吸引与辐射能力 ,城镇间经济联系弱 ,未能形成高原城镇体系。高原城镇化主要动力是自上而下型的政府投资拉动 ,然而也出现了一些新的投资主体 ,城镇化动力正向多元化发展。     

浮萍塘中氮归趋模式模拟分析

通过模拟分析浮萍塘中氮的循环迁移过程,考察了N主要迁移途径对各形态氮的去除贡献,并确定了水环境季节变化对氮循环过程影响.模拟结果显示:浮萍塘中氮的去除主要通过硝化/反硝化作用实现,而有机氮沉降以及氨氮挥发作用对TN去除贡献仅为2.1%.浮萍塘中氨氮和硝态氮的变化主要受硝化和反硝化作用影响;有机氮主要受藻类腐败以及氨化作用影响;底泥中氮的变化主要由有机氮沉降和底泥中氮氨化过程控制.此外,浮萍塘能有效去除水体中藻类,并维持藻类的较低含量;浮萍主要通过促进硝化/反硝化速率来提高系统对TN的去除能力.     

滇池流域荒台地植被恢复工程控制面源污染生态机理

利用标准径流小区技术研究了滇池流域荒台地植被恢复工程对水土及氮磷面源污染物控制效应,用枝叶吸附水量和土壤入渗特征指标评价了恢复的植被树冠截留和径流控制能力,分析了植物枝叶形态特征差异与树冠截留,人工植被恢复与径流调控的关系.结果表明,圣诞树、旱冬瓜和香根草对地表径流、土壤侵蚀及氮磷流失具有良好的控制作用.树冠截留能力强、土壤水库容量大的人工植被系统将导致地表径流、土壤侵蚀、氮磷流失显著减少.叶子小、无角质化、表面粗糙、有表皮毛、含水量低、生物量高,枝表面呈中等粗糙、不分泌脂类物质的植物,具有较高的鲜重吸附水率,能增加人工植被树冠截留.整地过程、植物根系生长和林隙灌草丛的自然恢复改善了荒台地土壤入渗性能,减少了地表径流,最终减轻了面源污染负荷.     

缺氧／厌氧／好氧工艺的脱氮除磷研究

通过实验研究缺氧环境倒置，来比较对Ａ／Ａ／Ｏ工艺脱氮除功能的影响。结果表明，与常规Ａ／Ａ／Ｏ（厌／缺／好）工艺相比，倒置后的工艺具有更好的脱氮除磷效果，在同等条件下，倒置系统的出水中ＰＯ４＾３－Ｐ明显降低，而比反硝化速率却可３０－５０％，该文还进一步揭示了聚磷微生物在各种环境下的释磷和吸磷规律及其相互关系。     

Aquatic arsenic: phytoremediation using floating macrophytes

Phytoremediation, a plant based green technology, has received increasing attention after the discovery of hyperaccumulating plants which are able to accumulate, translocate, and concentrate high amount of certain toxic elements in their above-ground/harvestable parts. Phytoremediation includes several processes namely, phytoextraction, phytodegradation, rhizofiltration, phytostabilization and phytovolatilization. Both terrestrial and aquatic plants have been tested to remediate contaminated soils and waters, respectively. A number of aquatic plant species have been investigated for the remediation of toxic contaminants such as As, Zn, Cd, Cu, Pb, Cr, Hg, etc. Arsenic, one of the deadly toxic elements, is widely distributed in the aquatic systems as a result of mineral dissolution from volcanic or sedimentary rocks as well as from the dilution of geothermal waters. In addition, the agricultural and industrial effluent discharges are also considered for arsenic contamination in natural waters. Some aquatic plants have been reported to accumulate high level of arsenic from contaminated water. Water hyacinth (Eichhornia crassipes), duckweeds (Lemna gibba, Lemna minor, Spirodela polyrhiza), water spinach (Ipomoea aquatica), water ferns (Azolla caroliniana, Azolla filiculoides, and Azolla pinnata), water cabbage (Pistia stratiotes), hydrilla (Hydrilla verticillata) and watercress (Lepidium sativum) have been studied to investigate their arsenic uptake ability and mechanisms, and to evaluate their potential in phytoremediation technology. It has been suggested that the aquatic macrophytes would be potential for arsenic phytoremediation, and this paper reviews up to date knowledge on arsenic phytoremediation by common aquatic macrophytes.     

全球气候变化的成因探析

探析了引起全球气候变化的温室气体效应、太阳变化、火山喷发、对流层气溶胶等外部强迫效应，以及导致大气和海洋间能量再分配的埃尔尼诺事件等所引起的气候变化。进一步讨论了气候系统内部的、涉及地球生物学和化学的几种气候反馈机制。     

生物脱氮技术中好氧反硝化细菌的代谢及应用研究进展

微生物脱氮是水体氮素去除最常用的有效方式,具有高效、经济和二次污染小等特点.好氧反硝化细菌的发现是微生物脱氮技术的重要里程碑,为新型生物脱氮领域的研发提供了新出路.当前,探究好氧反硝化细菌的脱氮特性及各环境因子（如碳源种类、C/N、温度、pH、DO、盐度、重金属含量等）在好氧条件下对反硝化过程的影响已成为污染水体氮素逸出的研究热点.通过总结好氧反硝化细菌的脱氮机制、筛选来源和种类、鉴定、脱氮特性与环境影响因素及其在实际含氮污染水体中的应用,结果表明,好氧反硝化细菌种类丰富、存在环境广泛,脱氮效率一般在50%以上;目前,好氧反硝化细菌脱氮机理的研究主要停留在氮的转化方面,对其中心碳的代谢研究以及碳氮比对反应机理的具体影响尚未明确,需要进一步探究;有关好氧反硝化细菌的脱氮特性研究尚处于实验室小试或中试阶段.建议进一步筛选高效菌群,进行碳氮代谢途径研究,优化好氧反硝化细菌固定化技术,并将其应用于实际工程中,减少水体中的氮素污染,对于实现高效、经济的脱氮具有重要社会价值.      

Formation mechanisms of nitrous acid (HONO) during the haze and non-haze periods in Beijing, China

As an important precursor of hydroxyl radical (OH), nitrous acid (HONO) plays a significant role in atmospheric chemistry. Here, an observation of HONO and relevant air pollutants in an urban site of Beijing from 14 to 28 April, 2017 was performed. Two distinct peaks of HONO concentrations occurred during the observation. In contrast, the concentration of particulate matter in the first period (period Ⅰ) was significantly higher than that in the second period (period Ⅱ). Comparing to HONO sources in the two periods, we found that the direct vehicle emission was an essential source of the ambient HONO during both periods at night, especially in period Ⅱ. The heterogeneous reaction of NO₂ was the dominant source in period Ⅰ, while the homogeneous reaction of NO with OH was more critical source at night in period Ⅱ. In the daytime, the heterogeneous reaction of NO₂ was a significant source and was confirmed by the good correlation coefficients (R²) between the unknown sources (P_unknown) with NO₂, PM_2.5, NO₂ × PM_2.5 in period Ⅰ. Moreover, when solar radiation and OH radicals were considered to explore unknown sources in the daytime, the enhanced correlation of P_unknown with photolysis rate of NO₂ and OH ($J_{{\mathrm{NO}}_2}$ × OH) were 0.93 in period Ⅰ, 0.95 in period Ⅱ. These excellent correlation coefficients suggested that the unknown sources released HONO highly related to the solar radiation and the variation of OH radicals.     

化学需氧量光度测定法探索

试验证明,ＣＯＤ光度测定法是可行的,本法测定范围为０～２００ｍｇ／Ｌ,测定波长为４３４ｎｍ,Ｋ２Ｃｒ２Ｏ７标准溶液最佳使用浓度为０．０６７５ｍｏｌ／Ｌ（１／６Ｋ２Ｃｒ２Ｏ７）在此浓度下ＣＯＤ为２００ｍｇ／Ｌ,的葡萄糖溶液实际测得值只比标准滴定法低１．８％。     

数字经济何以推动乡村生态振兴？——基于中国省级面板数据的经验证据

数字经济具有生态化的本质，是提高乡村生态演进韧性、全面推进乡村振兴的关键动力。在系统梳理数字经济对乡村生态振兴影响的直接机制、中介机制基础上，本文利用2010—2020年省级面板数据，运用固定效应模型、中介效应模型等方法，多维度实证考察了数字经济对乡村生态振兴的影响机制。研究结果表明：数字经济发展显著推动了乡村生态振兴，在运用分时间段检验、剔除特殊值方法进行稳健性检验后，该结论仍然成立。数字经济发展对乡村“三生”环境的影响大小有所差异，对乡村生活绿色宜居化的影响最大，对乡村生产绿色低碳化的影响次之，对乡村生态本底品质化的影响最小。中介效应显示，农村经济增长、绿色科技创新和环境规制都是数字经济助力生态振兴的重要机制。异质性分析表明，数字经济影响乡村生态振兴的效应大小呈现出“西部>中部>东部”态势，总体上，中西部地区数字经济的绿色赋能效应更为显著。因此，应强化农村数字基础设施建设，充分发挥数字经济在农村生态经济增长点培育、企业绿色科技创新及环境监管、宣教引导等方面的作用，因地制宜以差异化的数字化策略提升赋能乡村生态振兴的有效性。