On the potential of iPhone significant location data to characterize individual mobility for air pollution health studies

● We evaluated the accuracy of iPhone data in capturing time-activity patterns. ● iPhone data captured the most important microenvironments and time spent in them. ● iPhone data also accurately captured daily exposure to ambient PM pollution. ● A considerable fraction of the population in the USA may have iPhone data available. ● iPhone data has great potential in air pollution health studies. In many air pollution health studies, the time-activity pattern of individuals is often ignored largely due to lack of data. However, a better understanding of this location-based information is expected to decrease uncertainties in exposure estimation. Here, we showcase the potential of iPhone’s Significant Location (iSL) data in capturing the user’s historical time-activity patterns in order to estimate exposure to ambient air pollutants. In this study, one subject carried an iPhone in tandem with a reference GPS tracking device for one month. The GPS device recorded locations in 10 second intervals while the iSL recorded the time spent in locations the subject visited frequently. Using GPS data as a reference, we then evaluated the accuracy of iSL data in capturing the subject’s time-activity patterns and time-weighted air pollution concentration within the study time period. We found the iSL data accurately captured the time the subject spent in 16 microenvironments (i.e. locations the subject visited more than once), which was 93% of the time during the study period. The average error of time-weighted aerosol optical depth value, a surrogate of particle pollution, is only 0.012%. To explore the availability of iSL data among iPhone users, an online survey was conducted. Among the 349 surveyed participants, 72% of them have iSL data available. Considering the popularity of iPhones, iSL data may be available for a significant portion of the general population. Our results suggest iSL data have great potential for characterizing historical time-activity patterns to improve air pollution exposure estimation.     

Closing the knowledge-action gap in conservation with open science

The knowledge-action gap in conservation science and practice occurs when research outputs do not result in actions to protect or restore biodiversity. Among the diverse and complex reasons for this gap, three barriers are fundamental: knowledge is often unavailable to practitioners and challenging to interpret or difficult to use or both. Problems of availability, interpretability, and useability are solvable with open science practices. We considered the benefits and challenges of three open science practices for use by conservation scientists and practitioners. First, open access publishing makes the scientific literature available to all. Second, open materials (detailed methods, data, code, and software) increase the transparency and use of research findings. Third, open education resources allow conservation scientists and practitioners to acquire the skills needed to use research outputs. The long-term adoption of open science practices would help researchers and practitioners achieve conservation goals more quickly and efficiently and reduce inequities in information sharing. However, short-term costs for individual researchers (insufficient institutional incentives to engage in open science and knowledge mobilization) remain a challenge. We caution against a passive approach to sharing that simply involves making information available. We advocate a proactive stance toward transparency, communication, collaboration, and capacity building that involves seeking out and engaging with potential users to maximize the environmental and societal impact of conservation science.     

Fabricating data: how substituting values for nondetects can ruin results, and what can be done about it

The most commonly used method in environmental chemistry to deal with values below detection limits is to substitute a fraction of the detection limit for each nondetect. Two decades of research has shown that this fabrication of values produces poor estimates of statistics, and commonly obscures patterns and trends in the data. Papers using substitution may conclude that significant differences, correlations, and regression relationships do not exist, when in fact they do. The reverse may also be true. Fortunately, good alternative methods for dealing with nondetects already exist, and are summarized here with references to original sources. Substituting values for nondetects should be used rarely, and should generally be considered unacceptable in scientific research. There are better ways.     

Delineating high-density areas in spatial Poisson fields from strip-transect sampling using indicator geostatistics: application to unexploded ordnance removal

An approach for delineating high anomaly density areas within a mixture of two or more spatial Poisson fields based on limited sample data collected along strip transects was developed. All sampled anomalies were transformed to anomaly count data and indicator kriging was used to estimate the probability of exceeding a threshold value derived from the cdf of the background homogeneous Poisson field. The threshold value was determined so that the delineation of high-density areas was optimized. Additionally, a low-pass filter was applied to the transect data to enhance such segmentation. Example calculations were completed using a controlled military model site, in which accurate delineation of clusters of unexploded ordnance (UXO) was required for site cleanup.     

多源数据融合的城市区域型消防风险分布特征研究 ——以太原都市圈所在区域为例

分析区域消防风险的空间演化特征,针对性建立并调整消防站点,可预见性地降低消防风险.以太原都市圈所在区域作为研究对象,将遥感数据、POI兴趣点数据经标准化处理后融入GIS-GANP模型中,识别城市区域间特异性消防风险因子,探讨区域消防风险系数及空间分布特征,并多角度分析消防站点规划趋势.结果表明:POI数据符合区域融合发...     

Study on Residential Water Use in North China:Analysis of Nationwide Statistical Data and Case Study of Taiyuan City

Residential water use is gradually becoming the focus in China‘s municipal water supply planning and management in recent years. Little is known, however, about the residential water use in modem China due to the transition of economy and enhancement of management on water conservation. In order to better understand the characteristics of residential water use in North China, a model for identifying the determinants of residential water use was established and analyzed by using panel data and cross-section data methodologies. Then Taiyuan city, the capital city of Shanxi Province in Northern China was selected as a case study. Both the analyses and field investigation indicate that the relatively slow increase of residential water use in recent years may result from the implementation of strict laws and regulations on water conservation. And through the investigation,first-hand information about water consumption pattern, water reuse/conservation, people‘s attitude toward water quantity and quality, etc. have been obtained.     

鄱阳湖流域千年旱涝变化特点及R/S分析

为揭示鄱阳湖流域旱涝变化规律,预测未来变化,搜集整理了鄱阳湖流域地方志、奏折等古文献记载的旱涝记录,根据灾害现象、灾害后果、救灾情况等综合研判旱涝等级。对1160~1950s旱涝频次序列进行了变化周期分析。采用了R/S方法分析了年代际旱涝频次的Hurst指数,结合变化周期分析结果,对1950s以后鄱阳湖流域的旱涝频次变化趋势进行预测,采用基于1951~2010年器测降水量的SPI指数进行验证。研究结果表明:1160~1940s鄱阳湖流域及各子流域的干旱、洪涝频次呈波动变化,周期性变化明显,干旱、洪涝的3~6个年代周期段在整个时段内均非常显著,通过了95%的信度检验;鄱阳湖流域及各子流域的年代际干旱频次的Hurst指数普遍在0.7~0.8之间,洪涝在0.8~0.9之间。预测1950s后鄱阳湖流域年代际旱涝频次整体变化将呈阶段性上升趋势,经验证预测结果与实况较为吻合。     

集合最优插值同化方法在珠三角空气质量模拟中的初步应用

本文旨在探讨集合最优插值(EnOI)同化方法对MM5-STEM空气质量模式污染物浓度预报场的修正能力,先从局地化尺度(L)及经验系数(α)的敏感性试验中获得NO2、SO2和PM10各自的"最优L和α组合",然后对此参数设置下的同化结果进行分析.研究结果显示,EnOI在NO2、SO2及PM10的同化试验中均取得较好的效果,检验站点均方根误差(RMSE)的平均下降比例分别可达33%、32%和42%,RMSE值下降的站点占检验站点总数的比例分别为86%、84%和91%.表明该方法能够有效地应用在珠三角空气质量模拟中,产生与实际更为接近的污染物浓度预报场.     

巢湖地区无监测资料小流域面源磷污染输出负荷时空特征

在来自工业和城镇生活污水的点源污染得到有效控制的状况下,面源磷污染正逐步成为湖泊和河流富营养化的主导因子.在缺少监测资料的流域,移植处于同纬度和具有相同自然条件的流域的模型参数,是开展SWAT模型模拟的有效方法.因此,本文以巢湖地区的柘皋河小流域为例,通过移植率定好的模型参数,运用SWAT模型分析研究区面源磷污染输出负荷的时间变化和空间分布特征.结果表明,1980—2012年面源磷污染负荷围绕着平均值上下波动,不同水平年的磷污染负荷有较大差异,其中,1996—2012年的面源磷污染的年负荷大于1980—1995年的磷污染年负荷.两个时期内不同月份的总磷负荷均有显著性差异,其中,6—8月的磷污染负荷较大.两个时期的面源磷负荷的空间分布存在一定的差异,1996—2012年单位面积的面源磷负荷明显大于1980—1995年的单位面积面源磷负荷,其中,面源磷负荷的增加主要集中在水田区域.土地利用类型的变化和化肥的大量使用是导致研究区面源磷污染负荷增加的主要因素.     

黄土高原历史时期沟谷侵蚀量计算方法探讨

历史时期沟谷侵蚀量的计算多采用传统实地测量或计算方法,而现代地理信息技术的发展为沟谷侵蚀量计算提供了更为简便、快捷、高效的方式。等高线图形概括法即为一种将传统制图学与现代地理信息技术相结合的方法。本文以神木县东山旧城冲沟为切入点,采用等高线图形概括方法,基于30 m 分辨率ASTER DEM,利用Arcgis10 平台计算历史时期沟谷侵蚀量,并将其与基于野外测量计算侵蚀量进行对比。结果对比发现,基于野外测量的沟谷侵蚀量约占基于DEM 侵蚀量的89.11%,两者之间存在一定差距,但是可被接受的。进一步分析显示,等高线简化前后,DEM 平均坡度、等高线长度和表面积均发生变化,平均坡度、等高线长度变化率分别为2.78% 和4.3%,表面积变化不是特别明显。三维分析显示,简化后等高线更加平滑,平均坡度趋于平缓,坡度的分布更为均匀。总体而言,等高线图形概括方法在沟谷侵蚀量计算方面具有较高的可靠性,对更大时空尺度内的沟谷侵蚀量计算具有借鉴意义。