Demystifying uncertainty in PM10 susceptibility mapping using variable drop-off in extreme-gradient boosting (XGB) and random forest (RF) algorithms

Environmental Science and Pollution Research - This study investigates uncertainty in machine learning that can occur when there is significant variance in the prediction importance level of the...     

Statistical characterization of atmospheric PM10 and PM2.5 concentrations at a non-impacted suburban site of Istanbul, Turkey

Inhalable particulate matter (PM10) has been monitored at several stations by Istanbul Municipality. On the other hand, information about fine fraction aerosols (PM2.5) in Istanbul atmosphere was not reported. In this study, 86 daily aerosol samples were collected between July 2002 and July 2003. The PM10 annual arithmetic mean value of 47.1 microg m(-3), was lower than the Turkish air quality standard of 60 microg m(-3). On the other hand, this value was found higher than the annual European Union air quality PM(10) standard of 40 microg m(-3). Furthermore, the annual mean concentration of PM2.5 20.8 microg m(-3) was found higher than The United States EPA standard of 15 microg m(-3). The statistics and relationships of fine, coarse, and inhalable particles were studied. Cyclic behavior of the monthly average concentrations of PM10 and PM2.5 data were investigated. Several frequency distribution functions were used to fit the measured data. According to Chi-squared and Kolmogorov-Smirnov tests, the frequency distributions of PM2.5 and PM10 data were found to fit Log-logistic functions.     

The utility of electrocardiography and echocardiography in copper deficiency-induced cardiac damage in goats

Environmental Science and Pollution Research - Copper deficiency (CuD) is a common mineral disorder in ruminants, which causes histomorphological changes in the heart due to disturbances in...     

Medium scale LNG-related experiments and CFD simulation of water curtain

This work is a continuation of the experimental research on LNG releases and their consequence mitigation methods, which has been carried on by the Mary Kay O’Connor Process Safety Center (MKOPSC) at the Texas A&M University since 2004.A series of medium scale experiments to test the ability of the water curtains to hold up and disperse a vapor has been performed. Colored smoke has been used as an analog of the LNG vapor for easier tracking of the vapor path through the water curtain. The results and some analysis of the experimental data are presented. The CFD software FLACS (GexCon AS) was used to simulate the effects of the water curtains on vapor dispersion. The results of the simulations were compared with experimental data.     

Fate of napropamide herbicide in selected Malaysian soils

This study was carried out to determine the sorption-desorption, degradation and leaching of napropamide in selected Malaysian soils. The sorption capacities of the selected Malaysian soils for napropamide were the following in descending order: Linau > Teringkap > Gunung Berinchang > Jambu > Rudua > Baging soil. The results indicate that napropamide degradation decreased with increasing soil sorption capacity. Napropamide was leached out earlier in the Baging soil than the other soils. Overall, the application of napropamide in the selected Malaysian soils would not pose a threat to the environment except in soil with low organic matter and clay content and high hydraulic conductivity, such as the Baging soil.     

Assessment of the spring water quality in The Shoubak area,Jordan

The present study investigates the physical, chemical, and biological characteristics of spring water samples in Shoubak area in the southern Jordan. The samples were collected from May 2004 to May 2005. All samples were analyzed for temperature, conductivity, dissolved oxygen, pH, major cations (Ca²⁺, Mg²⁺, K⁺, Na⁺), major anions (Cl⁻, NO₃⁻, HCO₃⁻, SO₄²⁻, PO₄³⁻, F⁻), and trace metals (Fe²⁺, Al³⁺, Mn²⁺, Cu²⁺, Cr³⁺, Ni²⁺, Zn²⁺, Pb²⁺, Cd²⁺). Water quality for available springs showed high salinity through long period of contact with rocks. The ion concentrations in the water samples were from dissolution of carbonate rocks and ion exchange processes in clay. The general chemistry of water samples was typically of alkaline earth waters with prevailing bicarbonate chloride. Some springs showed elevated nitrate and sulfate contents which could reflect to percolation from septic tanks, cesspools, and agricultural practices. The infiltration of wastewater from cesspools and septic tanks into groundwater is considered the major source of water pollution. The results showed that there were great variations among the analyzed samples with respect to their physical, chemical and biological parameters, which lie below the maximum permissible levels of the Jordanian and WHO drinking water standards. The results indicate that the trace metals of spring’s water of Shoubak area do not generally pose any health or environmental problems. Factor analysis was used to identify the contributers to water quality. The first factor represents major contribution from anthropogenic activities, while the second one represents major contribution from natural processes.     

Effect of dissolved oxygen concentration on nitrite accumulation in nitrifying sequencing batch reactor.

A mathematical model based on Activated Sludge Model No. 3 (International Water Association, London) and laboratory-scale experiments were used to investigate ammonia conversion by nitrification in a sequencing batch reactor (SBR). The purpose of the study was to assess the effect of dissolved oxygen concentration on nitrite accumulation in the SBR. As the dissolved oxygen concentration in the SBR depends on the balance between oxygen consumption and oxygen transfer rates, ammonium conversion was measured for different air flowrate values to obtain different dissolved oxygen concentration profiles during the cycle. The ammonia concentration in the feeding medium was 500 mg ammonium as nitrogen (N-NH4(+))/L, and the maximum nitrite concentration achieved during a cycle was approximately 50 mg nitrite as nitrogen (N-NO2)/L. The air flow supplied to the reactor was identified as a suitable parameter to control nitrite accumulation in the SBR. This identification was carried out based on experimental results and simulation with a calibrated model. At a low value of the volumetric mass-transfer coefficient (kLa), the maximum nitrite concentration achieved during a cycle depends strongly on k(L)a, whereas, at a high value of k(L)a, the maximum nitrite concentration was practically independent of kL(a).     

The anthropogenic atmospheric elements fraction: A new interpretation of elemental deposits on tree barks

The superficial deposit on the bark surface of several trees (mainly Fraxinus excelsior L.) was sampled in the experimental station of the university campus in Grenoble (France). Its composition was studied by scanning electron microscopy–energy dispersive X-ray emission (SEM–EDX) and, after digestion, by inductively coupled plasma-mass spectrometry (ICP-MS). The deposit was composed of 81.3% ± 7.4 organic matter, 9.4% ± 4.9 of geogenic minerals issued from the atmosphere (atmospheric geogenic fraction: AGF) and 9.3% ± 2.7 of a mixture of elements which was called anthropogenic atmospheric elements fraction (AAEF). The SEM–EDX analysis showed the presence of particles of geogenic compounds such as different types of silicates, phosphates, carbonates, sulphates, oxides and also particles of metals such as iron or of alloys of Fe–Zn, Fe–Ni, Ni–Cr and Ca sulphates or phosphates. Typical spheres of “fly ashes” composed of pure iron or Al-silicates were detected. Using the SEM–EDX analysis of the deposit and the average local soil composition, an empiric formula for the AGF (without polluting elements) was chosen, which presented a clear analogy with the global formula of the upper continental crust. In the same way, a formula for the pure organic matter fraction was chosen. Withdrawing the elements corresponding to these two fractions allows a tentative estimation of the content of the AAEF which was supposed to better represent the elemental anthropogenic contamination issued from the atmosphere. In the station, most of Sb, Cd, Sn, Pb, Cu, V and Zn were found in the AAEF. This AAEF composition was compared to that of the deposit in a highway tunnel where Pb and Cu were at a very high level. The meaning and the limits of the AAEF concept were critically discussed.     

Effect of meteorological parameters on fine and coarse particulate matter mass concentration in a coal-mining area in Zonguldak, Turkey

In this work, the effect of meteorological parameters and local topography on mass concentrations of fine (PM2.5) and coarse (PM2.5-10) particles and their seasonal behavior was investigated. A total of 236 pairs of samplers were collected using an Anderson Dichotomous sampler between December 2004 and October 2005. The average mass concentrations of PM2.5, PM2.5-10, and particulate matter less than 10 microm in aerodynamic diameter (PM10) were found to be 29.38, 23.85, and 53.23 microg/m3, respectively. The concentrations of PM2.5 and PM10 were found to be higher in heating seasons (December to May) than in summer. The increase of relative humidity, cloudiness, and lower temperature was found to be highly related to the increase of particulate matter (PM) episodic events. During non-rainy days, the episodic events for PM2.5 and PM10 were increased by 30 and 10.7%, respectively. This is a result of the extensive use of fuel during winter for heating purposes and also because of stagnant air masses formed because of low temperature and low wind speed over the study area.