基于地理探测器的城市要素对街尘累积和磷污染空间分异影响特征分析

量化分析城市要素对街尘及其负载磷素空间分异的影响特征可帮助指导大尺度空间城市非点源磷污染管控.本研究结合地理大数据（兴趣点等）与实地采样数据,利用地理探测器定量探究武汉市汉阳区城市要素对街尘累积量及街尘负载多形态磷素含量空间分异的解释能力.结果表明：① 街尘累积量及街尘中磷素含量的空间分异程度随街尘粒径和磷形态变化.粒径<150 μm街尘累积量的空间分异程度相对较高;铝结合态磷（Al-P）、闭蓄态磷（Oc-P）和有机态磷（Or-P）的空间分异程度整体较高,而碎屑态磷（De-P）和总磷（TP）的空间分异程度则相对 较低;Oc-P和Or-P的空间分异程度随街尘粒径变化不大.② 单因子条件下,车站类（POI I）、住宅学校类（POI II）和工厂汽修类（POI III）要素对街尘累积量和多种形态磷含量空间分异的解释力较强;路网（ROAD）主要对粒径<150 μm街尘中部分磷素含量的空间分异有较强的解释力;餐饮商场类（POI IV）、娱乐休闲类（POI V）和医院类（POI VI）要素主要对>150 μm街尘中磷素含量的空间分异有明显的解释力;景点类（POI VII）要素则对街尘累积量和磷素含量空间分异的解释力较弱.③ 城市要素交互往往增强其对街尘累积量和街尘磷素含量空间分异的解释力,但路网（ROAD）、车站类（POI I）和景点类（POI VII）要素与部分城市要素交互容易对其解释力产生非线性减弱或单因子非线性减弱作用. ④ 基于城市要素布局对不同形态磷设置差异化的控制策略有利于街尘磷污染控制.     

基于浮游植物的北方景观河流水生态系统评价

文章通过对2017～2018年北京市房山区景观河流浮游植物及相应水环境因子春、夏、秋三季的监测,运用生物多样性、综合营养状态指数法,研究了浮游植物组成、结构、生物多样性评价与水环境质量响应关系。结果显示,房山区景观河流浮游植物以硅藻门、绿藻门为主;基于Pearson相关性分析,其总密度与叶绿素a(Chl a)呈现较高的正相关性;同时房山区景观河流生物多样性指标评价和水环境富营养化程度与水源结构、河流连通性相关,须考虑河流客观属性特征,采取针对性管控与优化措施。     

基于河流参照状态的季风区域季节性农业灰水足迹核算方法与例证

灰水足迹核算对水资源管理具有重要意义.灰水足迹核算的两个重要参数污染物自然本底浓度和污染物入河系数在季风区域均存在明显的季节性差异,而在之前灰水足迹核算的研究中较少考虑季风区域灰水足迹可能存在的季节性差异.本文以河流总磷的参照状态作为其自然本底浓度核算了承德市农业灰水足迹.结果发现：相较于将总磷自然本底浓度值认为零,将总磷参照状态作为其自然本底浓度值的农业灰水足迹核算结果是其核算结果的1.29倍.农业灰水足迹呈现明显的季节性差异,雨季农业灰水足迹是旱季农业灰水足迹的10.65倍.在2003—2015年承德市农业灰水足迹构成中,种植业灰水足迹占较大比重,并且该比重随时间有增大的趋势.然而,承德市区县粮食产量的增长率与化肥的增长率未表现出显著关系,说明粮食产量的增幅与化肥施用的增幅无关.承德市农业灰水足迹相对较大的区县集中于承德北部区域,主要包括围场县、丰宁县和隆化县;农业灰水足迹相对较小的区县为营子区、双滦区、双桥区和宽城县.本文可阐明季风区域农业灰水足迹核算的季节性差异,以期促进灰水足迹核算方法的发展.     

Variations in source apportionments of nutrient load among seasons and hydrological years in a semi-arid watershed: GWLF model results

Quantifying source apportionments of nutrient load and their variations among seasons and hydrological years can provide useful information for watershed nutrient load reduction programs. There are large seasonal and inter-annual variations in nutrient loads and their sources in semi-arid watersheds that have a monsoon climate. The Generalized Watershed Loading Function model was used to simulate monthly nutrient loads from 2004 to 2011 in the Liu River watershed, Northern China. Model results were used to investigate nutrient load contributions from different sources, temporal variations of source apportionments and the differences in the behavior of total nitrogen (TN) and total phosphorus (TP). Examination of source apportionments for different seasons showed that point sources were the main source of TN and TP in the non-flood season, whereas contributions from diffuse sources, such as rural runoff, soil erosion, and urban areas, were much higher in the flood season. Furthermore, results for three typical hydrological years showed that the contribution ratios of nutrient loads from point sources increased as streamflow decreased, while contribution ratios from rural runoff and urban area increased as streamflow increased. Further, there were significant differences between TN and TP sources on different time scales. Our findings suggest that priority actions and management measures should be changed for different time periods and hydrological conditions, and that different strategies should be used to reduce loads of nitrogen and phosphorus effectively.     

Net anthropogenic nitrogen accumulation in the Beijing metropolitan region

Background, aim, and scope  

A rapid increase in anthropogenic nitrogen inputs has a strong impact on terrestrial and aquatic ecosystems. We have estimated net anthropogenic nitrogen accumulation (NANA) as an index of nitrogen (N) pollution potential in the Beijing metropolitan region, China. Our research provides a basis for understanding the potential impact of anthropogenic N inputs on environmental problems, such as nation-wide water quality degradation under the current rapid urban expansion in modern China.