Development of an MFC-biosensor for determination of Pb+2: an assessment from computational fluid dynamics and life cycle assessment perspectives.

Microbial fuel cell (MFC)-based biosensor sensing has emerged as an innovative approach to in situ and immediate monitoring of substrate concentration. MFC-biosensor uses bioanode as a sensing element. In this study, the performance of MFC-biosensor, operated with Pb+2, was studied at different hydraulic retention times (HRTs). The HRT ranges were 0.5, 1, and 2 days. The power density generation increased with the decreasing HRT. The highest achievable power density was obtained at HRT of 1 days with the density value of 597 mW/m2. The power density produced in the MFC system was stored in the energy storage system. The computational fluid dynamics (CFD) method simulates detailed three-dimensional flow and heat transfer properties in reactors and provides information about potential reactor design. CFD was chosen to simulate the concentration distribution of the substrate in the MFC in different reactor type and different HRTs. It was observed that there was good turbulence in the reactor in a two day HRT and the reactor volume was used effectively. Life cycle assessment (LCA) was performed at 1 day with the highest power density. An LCA was implemented to the production and operation processes of a microbial fuel cell. According to the results, these two processes caused 4.23 × 10-6 loss of healthy years, extinction of 1.3 × 10-8 species in a year and loss of $ 0.33 source availability. The emissions to air, water, and soil were also calculated. These results showed that MFC-biosensor provided information on the rate of biodegradation processes.

Investigating the Combined Use of Enrichment Factor and Weather Research and Forecasting (WRF) Modelling for Precipitation Sample Source Identification: A Case Study in North Carolina, USA.

Pollutants emitted into the air not only have local effect but can also affect areas further from the source. The goal of this study was to assess a method for identifying the sources of element pollution in rainwater using enrichment factors supported by Weather Research and Forecasting (WRF) model. In this study, we collected nineteen rainwater samples at the two locations of Durham and Chimney Ridge in North Carolina, USA in July of 2014. The samples were analyzed for pH, conductivity and levels of major ions and a range of trace elements. These data showed that the pH of precipitation ranged between 3.91 and 6.65, with an average value of 4.98. The average electrical conductivity was 15.58 and 17.7 µS/cm for rainwater collected at Durham and Chimney Ridge, respectively. The lowest concentration of the elements analyzed was for thorium (Th) with an average concentration of 0.002 ppb, whereas the highest elemental concentration was for calcium (Ca) with an average concentration of 980.3 ppb. Enrichment factors for trace elements were assessed within three different groups as: (1) rarely enriched, (2) significantly enriched, and (3) highly enriched. Copper (Cu), zinc (Zn), arsenic (As), molybdenum (Mo), silver (Ag), cadmium (Cd), and lead (Pb) were highly enriched trace elements. The wind fields acquired by the WRF model indicated the probable contamination sources. Source identification indicated that the highest contribution of elements to precipitation was from industry. The results showed that the combined use of enrichment factors and the WRF model can be used to identify the sources of pollutants in precipitation samples.

Assessment of shipping emission factors through monitoring and modelling studies.

In this study, 3990 movements of 629 different ships approaching to the Ambarli port of Istanbul and 10,272 movements of 2798 different ships arriving at Kocaeli port which are the largest ports of Turkey were monitored for a year between September 1, 2017 and September 1, 2018. It is well known that ship exhaust emissions have a significant impact on pollutant and global warming agent mass inputs and diminish air quality around port areas. We calculated ship exhaust emissions for three different modes by ENTEC method. The annual estimated emissions were 72,802, 1430.4, 900.3, 105.3, 60.9, and 59 tons for CO2, NOx, SO2, PM10, VOC, and CO, respectively, in Ambarli Port. Higher emissions were estimated for Kocaeli Port due to marine traffic intensity. The annual estimated emissions at Kocaeli Port were 134,120.8, 2655.1, 1652.3, 181.4, 108.3, and 106.4 tons for CO2, NOx, SO2, PM10, VOC, and CO, respectively. In order to determine the impact of ship emissions, we employed AERMOD air quality dispersion modelling. Ground-level PM10, NOx, and SO2 concentrations were calculated. Their spatial distribution was plotted and results were evaluated by air quality measurement station results. Only estimated SO2 concentrations were higher than the observed concentrations. We concluded that ENTEC calculations produce excessive SO2 concentrations. Because sulphur content of marine fuel may vary and recent amendments in the related regulations limit its amount to lower values. Advancement of on-board SO2 emission control on ships can also have a reducing effect on emitted SO2 emissions. As a result, we emphasize that current ENTEC emission factors don't represent SO2 emissions accurately. Further, the advancement of SO2 emissions factors is required.

Distribution of Trace Metals in Street Dusts and Tree Leaves and Their Source Identification in a Mid-Populated Anatolian City.

Sivas is a central Anatolian city in Turkey with mid-population. Due to its geographical structure high air pollution episodes can be observed in the atmosphere of Sivas. A study with city wide sampling campaign can help to identify the possible sources. Therefore, we aimed to investigate the multi-elemental and multi-point analysis of trace metals in street dusts and tree leaves in Sivas. In the street dusts, Ca concentration was > 10%. Fe, Cl, and K contribution was 2.5%, 1.75%, and 1.1%, respectively. The average S and Ti concentrations were between 1 and 10 mg/g, I, Mn, Sr, Cr, V, Ba, Zn, Ni, Zr, and Cu were between 1 and 0.1 mg/g, and W, Pb, Sn, Th, Rb, Sb, Co, Bi, As, U were between 0.1 and 0.01 mg/g, in the ascending order. The same elements were investigated for vegetation. Ca, K, S, and Cl were the elements with highest contribution.

Investigation of geospatial distribution of PAH compounds in soil phase and determination of soil-air exchange direction in a megacity.

In this study, determination of possible sources, soil-air exchange direction, and spatial distribution of PAH concentrations was aimed. In this scope, soil samples were collected from 35 different points, which have the urban and rural characteristics, from European and Asian Sides in Istanbul. The average ∑16PAH concentrations were found as 22.11 ng/g dw for urban site and 19.53 ng/g dw for rural site, respectively. The highest concentration was 279.5 ng/g dw. PAH concentrations were higher in urban site than rural site. Acenaphthene and benzo[k]fluoranthene were observed as the dominant species. PAH concentrations are observed higher mostly in north and west parts of European Side and south and east parts of Asian Side. There was net evaporation from soil to air for lower molecular weight PAHs with 2, 3 rings, while high molecular weight PAHs with 4, 5, 6 rings accumulated in the soil at both urban and rural sites. PAHs were mostly originated from coal burning and the use of diesel engine vehicles.

Source identification of combustion-related air pollution during an episode and afterwards in winter-time in Istanbul.

Conventional air pollutants (PM10, CO, NOx) gradually increased from fall to winter during 2015 in Istanbul. Several air pollution episodes were observed during this period. This study was made in order to determine polycyclic aromatic hydrocarbon (PAH) levels, identify the sources of air pollution, and make toxicity assessment based on Benzo(a)pyrene equivalent concentrations. The sampling took 14 sequential days during winter. High-pressure weather conditions prevailed at the start of the sampling. The conditions were then changed to low-pressure condition towards the end of the sampling. Strong inversion was effective on the onset of the sampling. Strong inversion was effective at the onset of the sampling. A high-volume sampler was used to collect gas and particle phase samples. Total suspended particle concentrations were between 27 and 252 µg m-3. Sixteen PAH species were investigated. Total (gas + particle) PAH concentrations were between 76.4 and 1280.3 ng m-3, with an average of 301.4 ng m-3. Individual PAH concentrations were between not detected (n.d.) and 99.2 ng m-3 in the gaseous phase, and between n.d. and 11.5 ng m-3 in the particle phase. Phenanthrene had the highest share among 16 PAH compounds. Benzo(a)pyrene was not detected in 8 days. On the remaining days, its concentration ranged between 5.5 and 14.8 ng m-3 with an average of 3.7 ng m-3. Low-molecular-weight PAHs dominated gaseous phase; inversely, high-molecular-weight PAHs dominated particle phase. Possible sources were identified by diagnostic ratios. These ratios suggested that coal combustion and diesel vehicle exhaust emissions had a substantial impact on ambient air quality. Benzo(a)pyrene equivalencies were calculated for each PAH compound in order to make toxicity assessment. Total benzo(a)pyrene equivalencies ranged between 0.4 and 30.0 ng m-3 with an average of 7.2 ng m-3.

Evaluation of background soil and air polychlorinated biphenyl (PCB) concentrations on a hill at the outskirts of a metropolitan city.

Air and soil sampling was conducted inside a forested area for 22 months. The sampling location is situated to the north of a metropolitan city. Average atmospheric gas and particle concentrations were found to be 180 and 28 pg m(-3) respectively, while that of soil phase was detected to be 3.2 ng g(-1) on dry matter, The congener pairs of PCB#4-10 had the highest contribution to each medium. TEQ concentration was 0.10 pg m(-3), 0.07 pg m(-3), 21.92 pg g(-1), for gas, particle and soil phases, respectively. PCB#126 and PCB#169 contributed to over 99% of the entire TEQ concentrations for each medium. Local sources were investigated by conditional probability function (CPF) and soil/air fugacity. Landfilling area and medical waste incinerator, located to the 8 km northeast, contributed to ambient concentrations, especially in terms of dioxin-like congeners. The industrial settlement (called Dilovasi being to the east southeast of 60 km distant) contributed from southeast direction. Further sources were identified by potential source contribution function (PSCF). Sources at close proximity had high contribution. Air mass transportation from Aliaga industrial region (being to the southwest of 300 km distant) moderately contributed to ambient concentrations. Low molecular weight congeners were released from soil body. 5-CBs and 6-CBs were close to equilibrium state between soil/air interfaces. PCB#171 was close to equilibrium and PCB#180 was likely to evaporate from soil, which constitute 7-CBs. PCB#199, representing 8-CBs deposited to soil. 9-CB (PCB#207) was in equilibrium between soil and air phases.

Ambient polychlorinated biphenyl levels and their evaluation in a metropolitan city.

In this study, summer and autumn ambient PCB concentrations were investigated in metropolitan city of Istanbul. 84 congeners were targeted from di-CBs to nona-CBs on both particle and gaseous phases. Gaseous ambient concentrations were determined to be 372 ± 134 pg·m(-3), while on the particle phase this value was 49 ± 17 pg·m(-3), corresponding to an average of 420 pg·m(-3). About one-tenth of all PCBs lay in ambient aerosols, while 90% of all comprise 2-, 3-, 4-, and 5-CBs. Measured ambient concentrations of each congener group were tested against meteorological data. The di-CB concentrations were independent of ambient temperature while northerly winds lead to an increase in their concentrations, which was an indicator of considerable contribution to di-CB concentrations from the medical waste incineration plant in Istanbul. In contrast, other congeners' concentrations were found to be correlated with southerly winds. Being an inland sea and having been contaminated, for years, by industrial discharges along the coastline, volatilization from Marmara Sea was considered as the most probable source of other congeners. PSCF analysis was run with 12-hour trajectories to locate possible local sources and check these results. Gas/particle partitioning was applied using three different models. mr and br values for log PL(0) model were determined as -0.23 ± 0.09 and -3.25 ± 0.38, respectively. For absorption based log Koa model, m and b values were calculated as 0.23 ± 0.08 and -4.73 ± 0.83, respectively.

Investigation of temporal and spatial variations in atmospheric concentrations of PCDDs and PCDFs in Istanbul.

In this study, temporal and spatial variations of the atmospheric concentrations of polychlorinated-p-dibenzo dioxin (PCDDs) and polychlorinated dibenzofuran (PCDFs) congeners were investigated in Istanbul at three different locations. The highest average concentration (3481 fg/m(3)) was observed at the sampling location which is characterized by mixed source groups during colder months. The lowest average concentration (749 fg/m(3)) was observed at sampling station which is characterized by semi-urban characteristics. ∑PCDD/F concentration showed seasonal variation in this study. The highest average concentration was determined to be 4373 fg/m(3) in winter while the lowest average concentration was determined to be 498 fg/m(3) in summer.

A detailed investigation of ambient aerosol composition and size distribution in an urban atmosphere.

This research was executed between March 2009 and March 2010 to monitor particulate matter size distribution and its composition in Istanbul. Particulate matter composition was determined using ion chromatography and inductively coupled plasma optical emission spectrometry. The sampling point is adjacent to a crowded road and the Bosporus Strait. Two prevailing particulate modes are found throughout PM10 by sampling with a nine-stage low-volume cascade impactor. First mode in the fine mode is found to be between 0.43 and 0.65 µm, whereas the other peak was observed between 3.3 and 4.7 µm, referring to the coarse mode. The mean PM10 concentration was determined as 41.2 µg/m(3), with a standard deviation of 16.92 µg/m(3). PM0.43 had the highest mean concentration value of 10.67 µg/m(3), making up nearly one fourth of the total PM10 mass. For determining the effect of traffic on particulate matter (PM) composition and distribution, four different sampling cycles were applied: entire day, nighttime, rush hour, and rush hour at weekdays. SO4(-2) and organic carbon/elemental carbon proportions are found to be lower in night samples, representing a decrease in traffic. The long-range transports of dust storms were observed during the sampling periods. Their effects were determined analytically and their route models were run by the HYSPLIT model and validated through satellite photographs taken by the NASA Earth Observatory.

Effect of diurnal changes in VOC source strengths on performances of receptor models.

INTRODUCTION: The effect of diurnal changes in strengths of volatile organic compound (VOC) sources on the performances of positive matrix factorization (PMF) and principal component analysis (PCA) was investigated using ambient measurement results that were taken during daytime and nighttime hours between March 24 and May 14, 2011, within Davutpasa Campus of Yildiz Technical University (Istanbul, Turkey). METHODS: Forty-five VOC species, ranging from C(5) to C(11) in volatility, were measured in the samples, 40 of which are included in the analyses. Ambient samples were grouped as daytime, nighttime, and all day datasets, and both PMF and PCA were applied to each dataset. A total of six source groups were extracted from each dataset: solvent use, general industrial paint use, gasoline and diesel vehicle exhausts, and biogenic as well as evaporative emissions. Estimated source contributions showed great diurnal variations. RESULTS: The results suggested that extraction of possible sources by PCA depends greatly on the number of samples and the strength of the sources, while PMF produced stable results regardless of number of samples and source strengths. CONCLUSION: Although PMF was unable to resolve gasoline vehicle and evaporative emissions, it was found to be successful in explaining diurnal fluctuations in source strengths, while the performance of PCA depends on the strength of emission source.