Significance of dredging on sediment denitrification in Meiliang Bay, China： A year long simulation study

An experiment for studying the effects of sediment dredging on denitrification in sediments was carried out through a one-year incubation of undredged (control) and dredged cores in laboratory. Dredging the upper 30 cm of sediment can significantly affect physico-chemical characteristics of sediments. Less degradation of organic matter in the dredged sediments was found during the experiment. Denitrification rates in the sediments were estimated by the acetylene blockage technique, and ranged from 21.6 to 102.7 nmol N2/(g dry weight (dw)·hr) for the undredged sediment and from 6.9 to 26.9 nmol N2/(g dw·hr) for dredged sediments. The denitrification rates in the undredged sediments were markedly higher (p0.05) than those in the dredged sediments throughout the incubation, with the exception of February 2006. The importance of various environmental factors on denitrification was assessed, which indicated that denitrification was regulated by temperature. Nitrate was probably the key factor limiting denitrification in both undredged and dredged sediments. Organic carbon played some role in determining the denitrification rates in the dredged sediments, but not in the undredged sediments. Sediment dredging influenced the mineralization of organic matter and denitrification in the sediment; and therefore changed the pattern of inherent cycling of nitrogen.     

利用31P核磁共振技术优化太湖沉积物有机磷的化学提取方法

以太湖沉积物为研究对象,采用钼酸铵比色方法与液相31P-核磁共振技术(31P-NMR),研究不同浓度NaOH及NaOH与EDTA不同配比(NaOH-EDTA)对沉积物有机磷的提取及31P-NMR组成分析的影响.结果表明:不同浓度NaOH或不同配比的NaOH-EDTA,其提取沉积物总磷和有机磷量均随溶液pH值的增加而增加...     

太原市PM2.5积累特征及重污染天气成因分析

收集了太原市2014-2018年秋冬季（10月-翌年2月） PM_2.5、SO₂、NO₂和CO浓度数据以及对应时刻气象资料,基于逐日PM_2.5在16：00-01：00时的变化将其分为消散过程、慢速积累过程和快速积累过程,从PM_2.5积累的角度分析了太原市PM_2.5的污染特征及影响因素,并将其运用于重污染天气形成过程的探讨.结果表明,太原秋冬季慢速积累过程占比最高为44%,快速积累过程占27%,消散过程占29%.10月以慢速积累为主占比超过60%,11和12月快速积累占比最高接近40%,1、2月慢速积累再次占主导地位;快速积累过程占比最高的年份为2014年和2016年均超过35%,慢速积累和消散占比最高的年份均为2017年.慢速积累状态下,二次污染物的生成有助于PM_2.5的积累速率增加;快速积累状态下一次污染物对PM_2.5积累速率影响更明显;发生快速积累时,来自临汾、晋城等东南方向区域输送显著增加.太原市重污染天气的形成过程以慢速积累为主,占比77%.重污染天气下,市区多以硫酸盐和硝酸盐复合污染为主,而郊区以硝酸盐污染为主.     

沉积物间隙水溶解态磷和铁（Ⅱ）高分辨同步分析方法的研究

沉积物具有高度的空间异质性,尤其在沉积物-水界面附近的微环境中,溶质在微小尺度上可能存在强烈的浓度梯度分布,需要借助高分辨的获取技术才能表征。本研究发展了一种沉积物微界面溶解态反应性磷（Dissolved Reactive Phosphorus,DRP）和溶解态铁（Ⅱ）的同步分析方法。利用分辨率为4 mm、平衡时间仅为2 d的微型间隙水平衡装置（Peeper装置）获取微量间隙水（～100μL·样品-1）,采用384微孔板微量比色法分别测定同一间隙水样品中的DRP和溶解态铁（Ⅱ）的质量浓度,单一指标所消耗的间隙水体积由5 mL减少到仅～40μL,检出限分别为0.009和0.017 mg·L-1,精密度为1%～7%,均与常规方法相近。将该分析方法应用到太湖两个湖区的沉积物中,同步获得的微界面溶解态磷和铁（Ⅱ）的分布较好地反映了两者的关系。     

Exogenous fulvic acid enhances stability of mineral-associated soil organic matter better than manure

Environmental Science and Pollution Research - Mineral-associated soil organic matter (MAOM) is seen as the key to soil carbon sequestration, but its stability often varies with types of exogenous...