Temporal Variations Of Pollutants Research Articles

Spatial patterns and temporal variations of pollutants at 56 air quality monitoring stations in the state of São Paulo, Brazil.

This study applied two data mining tasks: clustering and association rules to a dataset of pollutants in the state of São Paulo. The clustering task was applied to temporal patterns and geospatial distributions of pollutants, and the association rules were used to identify prevailing meteorological conditions when there were high concentrations of pollutants from 2017 to 2019. The results indicated good adequacy of the cluster, indicating different pollution levels per group, with a silhouette coefficient from 0.26 to 0.72. In the spatial evaluation, the groups severely polluted were located in the metropolitan region, on the coast and, some inland cities, by industrial, vehicular, burning, agriculture, and other emissions. The cluster identified a strong presence of O3 and PM2.5 in 65% and 72% of the monitored stations in several areas of the state. As for the distance between the sources of pollution, the groups of PM10 and NO2 were geographically distant, while PM2.5, CO, SO2, and O3 were closer, suggesting a spatial relationship of exposure. Seasonality was similar between groups, with significantly higher concentrations in winter, except for O3, for which higher concentrations occurred in summer. Meteorological conditions contributed to critical episodes of pollution (support and confidence greater than 80%), with low temperature and humidity, low rainfall, and milder wind associated with increased pollutants. In conclusion, investigating spatial representativeness allows revealing spatial and temporal patterns of pollutants and unfavorable meteorological conditions to diffusion. Thus, ideal and effective measures can be taken to avoid critical periods of exposure based on the behavior of pollutants in different regions and related climate changes.

Spatial and temporal variation of particulate matter and gaseous pollutants in China during 2014–2016

China is experiencing severe air pollution due to rapid economic development and accelerated urbanization. High-resolution temporal and spatial air pollution data are imperative to understand the physical and chemical processes affecting air quality of China. The data of PM2.5, PM10, SO2, CO, NO2, and O3 in 187 Chinese cities during January 2014 and November 2016 were collected to uncover the spatial and temporal variation of the pollutants in China. The annual mean concentrations of PM2.5 exceeded the Grade I standard of Chinese Ambient Air Quality (CAAQS) for all of the cities except several cities in Hainan, and more than 100 cities exceeded the CAAQS Grade II standard. The concentrations of PM2.5, PM10, SO2, CO, and NO2 decreased from 2014 to 2016, whereas the O3 level increased dramatically during this period. The concentrations of PM2.5, PM10, SO2, CO and NO2 exhibited the highest levels in winter and the lowest in summer, and evidently decreased from 2014 to 2016, whereas the O3 concentration peaked in spring and summer, and dramatically increased from 2014 to 2016. The non-attainment ratios were highest in winters, while high pollution days were also frequently observed in the Southeast region in autumn and in the Northwest region in spring. Pearson correlation analysis indicated that all of the pollutants exhibited significant correlation one another. PM10 was a major pollutant affecting the air quality of China in all of the seasons. Both SO2 and NO2 exerted significantly adverse effects on the air quality in spring and autumn, but CO played an important role on the air quality in winter. O3 was found to be the dominant species among the pollutants affecting the air quality in summer, suggesting that photochemical O3 formation should be paid more attention to improve the air quality in summer. The results of geographical weight regression (GWR) showed that more significant correlations among the pollutants and the highest air quality index (AQI) appeared in the south of China. The impacts of PM10 and NO2 on the air quality increased from the east to the west of China, while SO2 and O3 exhibited the opposite variation. The data presented herein supplied an important support for the future source apportionment and intra- and inter-regional transport modeling of pollutants.

Magnetic susceptibility mapping of the Sudbury area, Ontario, Canada: evaluating pollution distributions decades later

This study evaluates the use of magnetic susceptibility and magnetic parameter measurements in assessing spatial and temporal variations of pollutants that emanated from mining industries in and around Sudbury, Ontario, Canada. For this purpose, in situ magnetic susceptibility (κin situ) was measured at 106 sites on a grid of 10 km × 10 km and 5 km × 5 km. The κin situ values ranged from 2 × 10−5 to 149 × 10−5 SI, and the highest κin situ values were observed near the active (Copper Cliff) and inactive (Coniston) mining sites. The lowest κin situ values were measured at increased distances from possible pollution sources; therefore, mapping of in situ magnetic susceptibility values is a proxy to polluted areas in and around Sudbury. To evaluate potential anthropogenic and (or) lithogenic input to κin situ, low-frequency mass specific magnetic susceptibility (χlf) variations with depth were classified into four different types of profiles. For further investigation of magnetic minerals in the samples, laboratory measurements of magnetic susceptibility, frequency dependence of magnetic susceptibility, hysteresis properties, thermosusceptibility curves, anhysteretic and isothermal magnetizations, and scanning electron microscopy – energy-dispersive X-ray spectroscopy (SEM–EDS) were also conducted on the soil samples. Laboratory measurements indicated that ferrimagnetic minerals (e.g., magnetite) of variable grain size were the dominant magnetic minerals, with the exception of one site that contained an iron sulfide (greigite) phase near a mine waste site. Magnetic spherules observed in SEM micrographs are of variable sizes (6–60 μm), suggesting that suspended particulate matter (PM10) is present, and may be a health concern. At some sites, EDS analysis showed that heavy metals (Co, Al, and Ni), which threaten human health, are also present in the study area.

Spatial and temporal variations of river water quality: A case study of River Kabini at Nanjangud in Karnataka

Water pollution is alarming all over the globe and necessitates better understanding of spatial and temporal variations of pollutants in the rivers. In this study, the data sets of 8 water quality monitoring stations in River Kabini at Nanjangud which comprised of 10 water quality parameters monitored monthly over 12 years (2000-2011) are used. Temporal variation of the physico-chemical parameters in each station is represented by Box plots. High positive skewness is observed for total dissolved solids (TDS), conductivity, chemical oxygen demand (COD), and chlorides for all stations, showing rampant pollution in the river due to anthropogenic sources. The microbiological parameters in each station shows the river is polluted with total coliform and faecal coliform across baseline, trend and impact stations. The results suggest that the Kabini River is polluted from anthropogenic sources because bathing ghat exists along the river and domestic wastewater is let into the river without treatment. This study provides critical information for river conservation and its protection by suggesting possible treatment of domestic wastewater before letting in the river. Key words: Box plots, temporal variation, anthropogenic sources, total coliform, faecal coliform.

Investigation of a solvent polluted industrial site on a deep sandstone-mudstone sequence in the UK. Part 2. Contaminant sources, distributions, transport and retardation

A single industrial site has been investigated in detail to gain information on sources and movement of chlorinated hydrocarbon solvent (CHS) pollutants in groundwater under the industrialized city of Conventry in the UK. A soil gas survey identified the most polluted area of the site where two types of investigation borehole were drilled; open boreholes lined with plain and slotted casing, and a single dedicated borehole incorporating gas samplers and gas-driven water samplers. Specially designed sampling techniques using pumps and packers were employed to determine vertical pollution profiles in the open boreholes. Core material was collected for sorption and diffusion experiments. An assessment of field investigation procedures suggests that soil gas sampling is a useful method for reconnaissance surveying of pollution by volatile organic compounds, but the results reflect only shallow pollution in the vertical profile. Open boreholes were found not to be satisfactory for accurate groundwater profile sampling and dedicated boreholes are recommended for such studies. Many uncertainties are involved in such a study of solvent pollution owing to the limited number of boreholes drilled and the complex spatial and temporal variations of pollutants. Despite the limitations of the investigation, several useful conclusions are drawn concerning sources and movement of solvent pollution. The main pollution source at the site is identified as the solvent storage tanks and pollution has resulted from poor use practices. Vertical pollution profiles indicate that the downward migration of 1,1,1-trichloroethane is following that of trichloroethene, reflecting their history of use on the site. The overall quality of groundwater abstracted in the system is set to deteriorate, as high pollution loads, presently at shallow levels in the system penetrate deeper, little attenuated by sorption or degradation. Diffusion of pollutants between mobile fissure and immobile pore waters will result in poor quality groundwater under this site for the foreseeable future. This trend is expected to be reflected throughout the urban area as a whole, with most groundwaters falling below drinking water standards for CHSs.

Hydraulic Performance and Control of Pollutants Discharged from a Combined Sewer Storage Overflow

The development of the Wallingford Procedure WASSP (1981) and the MOSQITO (Moys 1987) models will provide the sewerage engineer with design tools to assess the quantitative and qualitative performance of sewer systems. As part of the development of such a quality model, the University of Manchester, financed by the Water Research centre and North West Water, have undertaken a fieldwork program of research to monitor the hydraulic performance and the temporal variation of pollutants in the inflow and the overflow at five combined sewage overflows in the North West of England. These projects are integrated into the program of research co-ordinated by the River Basin Management group at WRc Engineering. This paper describes the instrumentation used at a typical field site and illustrates the monitored temporal variation of pollutants for a number of storm events. These results show the complexity of the monitored pollutographs and highlight the large number of variables which influence combined sewer quality. Using data monitored in 1986, it is hypothesised that the long term impact of combined sewer discharges on receiving waters may be estimated from the flow retention performance and some estimate of annual average pollutant concentration. To predict the short term impact on river quality it is necessary to consider the complex processes associated with combined sewer flow and to include the separation performance of the overflow structure.