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"Apportionment"
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Is This the End of Close Elections?
Rampant gerrymandering and intense partisan sorting have shrunk the number of competitive House seats to a record-low. The political scientist Lee Drutman explains how on “The Ezra Klein Show.”
Streaming Video
Representation and inequality in late nineteenth-century America : the politics of apportionment
\"This book examines fierce conflicts over apportionment and gerrymandering in the late nineteenth-century Midwest\"-- Provided by publisher.
Book
Understanding the California and Texas redistricting fight
California Democrats are racing to approve a new congressional map, seeking to counter Texas Republicans ahead of next year’s midterm elections.
Streaming Video
Systemic And Structural Racism: Definitions, Examples, Health Damages, And Approaches To Dismantling
Racism is not always conscious, explicit, or readily visible- often it is systemic and structural. Systemic and structural racism are forms of racism that are pervasively and deeply embedded in systems, laws, written or unwritten policies, and entrenched practices and beliefs that produce, condone, and perpetuate widespread unfair treatment and oppression of people of color, with adverse health consequences. Examples include residential segregation, unfair lending practices and other barriers to home ownership and accumulating wealth, schools' dependence on local property taxes, environmental injustice, biased policing and sentencing of men and boys of color, and voter suppression policies. This article defines systemic and structural racism, using examples; explains how they damage health through many causal pathways; and suggests approaches to dismantling them. Because systemic and structural racism permeate all sectors and areas, addressing them will require mutually reinforcing actions in multiple sectors and places; acknowledging their existence is a crucial first step.
Journal Article
Source apportionment of airborne particulate matter in a Chinese megacity : modelling comparison
Jinan is one of the most polluted mega-cities in China, which is primarily due to the high levels of PM2.s. A quantitative understanding on the sources of PM2.s is a prerequisite to control the severe pollution. In this project, 103 PM2.s samples were collected and their chemical composition, including water-soluble ions, trace metals, organice carbon, elemental carbon and organice molecular markers, were measured. Mass closure anlysis reveals that OM (29%), sulphate (18%), nitrate (10%), ammonium (9%) and geological material (9%) are the major chemical components in PM2.s in Jinan. The data were fed to both PMF and CMB models for source apportionment and uncertainty analysis. PMF and CMB have identified secondary inorganic aerosol (41%; 31%), coal burning (10%; 16%), biomass burning (20%; 17%), vehicle emission (16%; 14%) and mineral dust (10%; 6%) as the major PM2.s sources in Jinan, respectively. CMB also identified the metallurgic plant (11 %) production as a potentially important source of Jinan's PM2.s. Furtherwork needs to be done including using other source identifications such as back trajectory, chemical transport model and remote sensing. Longer sampling periods is also recommended and establishing the local source profile is vital for the source apportionment in Jinan in the near future.
Dissertation
Airborne particulate matter
Airborne particulate matter (PM) is a pollutant of concern not only because of its adverse effects on human health but because of its ability to reduce visibility and soil buildings and materials. It can be regarded as a suite of pollutants since PM covers a very wide range of particle sizes and also has a diverse chemical composition. Historically, much of the PM arose from coal burning and was measured as black smoke. However, in the second half of the twentieth century in developed countries, there was a reduction in black smoke emissions from coal burning and PM steadily became dominated by carbonaceous particles from road traffic exhaust and the secondary pollutants, ammonium salts and secondary organic carbon. This is exemplified by the composition of fine particles (referred to as PM 2.5 ) as measured in London, Delhi and Beijing. Steadily, as control strategies have addressed the more tractable sources of emissions, so sources previously regarded as unconventional have emerged and have been seen to make a significant contribution to airborne PM concentrations. Among these are non-exhaust particles from road traffic, cooking aerosol and wood smoke. The particle size distribution of airborne PM is hugely diverse, ranging from newly formed particles of a few nanometres in diameter through to particles of tens of micrometres in diameter. There has been a great deal of interest in ultrafine (nano) particles because of suspicions of enhanced toxicity, and as traffic emissions decrease as a source, so regional nucleation processes have become much bigger relative contributors to particle number, but not mass. This article is part of a discussion meeting issue ‘Air quality, past present and future’.
Journal Article
Contamination, Source Apportionment, and Health Risk Assessment of Heavy Metals in Farmland Soils Surrounding a Typical Copper Tailings Pond
Tailings resulting from mining and smelting activities may cause soil heavy-metal pollution and harm human health. To evaluate the environmental impact of heavy metals from tailings on farmland soils in the surrounding area, heavy metals (As, Cd, Cr, Cu, Ni, Pb, and Zn) in tailings and farmland soils in the vicinity of a typical copper tailings pond were analyzed. Contamination status, potential sources, and health risks for farmland soils were investigated. The results showed that the tailings contained a high concentration of Cu (1136.23 mg/kg). The concentrations of Cd and Cu in the farmland soils exceeded the soil quality standard. The geoaccumulation index (Igeo) indicated that the soils were moderately polluted by Cu and Cd, and slightly polluted by Ni, Cr, and Zn. The absolute principal component scores–multiple linear regression (APCS-MLR) model was applied for source apportionment. The results showed that tailings release is the main source of soil heavy-metals contamination, accounting for 35.81%, followed by agricultural activities (19.41%) and traffic emission (16.31%). The health risk assessment suggested that the children in the study region were exposed to non-carcinogenic risks caused by As, while the non-carcinogenic risk to adults and the carcinogenic risk to both adults and children were at acceptable levels. It is necessary to take effective measures to control heavy-metal contamination from tailings releases to protect humans, especially children, from adverse health risks.
Journal Article
The spatial distribution and source apportionment of heavy metals in soil of Shizuishan, China
Environmental pollution of heavy metals in the typical coal industrial city should be paid more attentions nowadays. The spatial distribution and source apportionment of 8 heavy metals (i.e., Cd, Cr, Co, Zn, Ni, Cu, Pb and Mn) from topsoil samples (158) of Shizuishan city in Ningxia Hui Autonomous Region of China were investigated using principal component analysis/absolute principal component scores (PCA/APCS) receptor model and geographic information system (GIS). These results showed that the mean concentrations of Cd, Cr, Co, Zn, Ni, Cu and Pb were higher than their soil background values in Ningxia. 99.36% of soil samples were heavily polluted according to analysis of integrated Nemerow pollution index (PN), whereas 81.65% of soil samples exhibited the highly strong potential ecological risk by ERI (the comprehensive of potential ecological risk index) values. The source apportionment results showed that eight heavy metals in soil were mainly from natural (32.39%), industrial (26.56%), traffic emission/coal consumption (20.18%) and atmospheric deposition source (12.73%). Typically, Zn, Mn and Ni were derived from natural source, whereas Cr and Co were mainly derived from industrial sources. Cu was from the multiple sources, whereas Pb and Cd were weighted primarily from traffic emission/coal consumption source and atmospheric deposition source, respectively. These findings were crucial for the prevention and control of heavy metals pollution in Shizuishan city.
Journal Article
Tracing Nitrate Contamination Sources and Transformations in a Rural−Urban Karst Groundwater System in North China Using Multiple Isotopes and Simmr Modeling
In temperate karst aquifers under intensive anthropogenic impacts and high heterogeneity, groundwater contamination tracking has predominantly focused on nitrate, but inadequate evidence for co‐occurring ammonium sources undermines accurate nitrogen pollution assessments. This study pioneered the application of a δ15NNH4${\\delta }^{15}{\\mathrm{N}}_{{\\text{NH}}_{4}}$isotope approach within the groundwater flow framework of the Jinan Spring Catchment, constructed a novel ammonium‐nitrate isotope tracing system (δ15NNH4${\\delta }^{15}{\\mathrm{N}}_{{\\text{NH}}_{4}}$ , δ15NNO3${\\delta }^{15}{\\mathrm{N}}_{{\\text{NO}}_{3}}$ , and δ18ONO3${\\delta }^{18}{\\mathrm{O}}_{{\\text{NO}}_{3}}$ ) for full‐form source tracking, and implemented the Bayesian mixing model (Simmr) to quantitatively apportion nitrate sources in karst groundwater. This integrated system enabled simultaneous NH4+‐N and NO3−‐N pollution source identification, enhancing the resolution of key nitrogen cycling pathways, particularly ammonium‐dominated nitrification. The NO3−‐N was the dominant form of inorganic nitrogen in karst groundwater (0.4−42.2 mg/L), and demonstrated an overall upward trend from 1958 to 2019. δ15NNH4${\\delta }^{15}{\\mathrm{N}}_{{\\text{NH}}_{4}}$and nitrate isotope both confirmed that NH4+‐N and NO3−‐N primarily originated from ammonium fertilizer and soil nitrogen. The Simmr model quantified ammonium fertilizer (28.4%−58.3%) and soil nitrogen (23.1%−62.7%) as primary contributors to groundwater NO3−‐N. Hydrochemical and dual nitrogen isotope evidences revealed that mineralization and re‐nitrification of soil nitrogen, nitrification of ammonium fertilizers, and mineralization‐immobilization‐turnover of nitrate fertilizers all promoted nitrate accumulation in karst groundwater. Groundwater flow analysis identified mixing between shallow and deep karst groundwater as the primary mechanism for nitrate attenuation of spring waters in the urban discharge area, with denitrification playing a negligible role. These findings provide new insights into nitrogen behavior in temperate karst groundwater, offering valuable guidance for water resource management and protection in similar karst systems.
Journal Article