Maximum Average Concentration Research Articles

Development of a method to assess the risk of aflatoxin contamination of corn within counties in southern Georgia, USA using remotely sensed data

Aflatoxins (AFs) are carcinogenic toxins produced by fungi in many staple grain crops. FDA legislative thresholds for the maximum allowable average AFs concentrations in grain intended for different uses determine if whole batches of grain are rejected or must be used for a less lucrative purpose. Few spatial studies of aflatoxin contamination in the field have been undertaken as AFs analysis is expensive, but such studies are key to improving food security. High risk areas need to be identified to allow management strategies to reduce the amount of wasted grain. AFs production tends to be greatest in high temperature and drought conditions. Previous research has suggested that local Moran's I (LMI) analysis of weather and remotely sensed imagery can identify locations at high risk of AFs contamination but this has not been validated with AFs data. This study uses a 1977-2004 AFs survey of counties in southern Georgia, USA with NDVI and thermal IR data from 1990-2004 imagery to validate this approach. Also investigated in this paper, as they are integral to the validation approach used, are issues relating to the identification of corn growing pixels in historical imagery and a modified kriging approach to interpolate the sparse AFs data for individual years. Comparison tests showed that significantly more high-risk points were identified by bivariate LMI analysis of thermal IR and NDVI in high-risk years than low and medium risk years and these pixels had significantly higher AFs concentrations than other pixels. AFs concentrations were not significantly higher for high-risk clusters in low and medium risk years. LMI analysis from all years suggested that imagery data was better at identifying drought risk than interpolated weather data alone as it also shows the effects of droughty soils. The approach developed here could be used with CropScape data, historic remotely sensed imagery and weather data to determine risk zones for other states in the south or other crops in Georgia. The approach developed for kriging sparse data could also be useful in a range of other environmental studies.

Clinically relevant dosing and pharmacokinetics of DNA-encoded antibody therapeutics in a sheep model

DNA-encoded delivery and in vivo expression of antibody therapeutics presents an innovative alternative to conventional protein production and administration, including for cancer treatment. To support clinical translation, we evaluated this approach in 18 40-45 kg sheep, using a clinical-matched intramuscular electroporation (IM EP) and hyaluronidase-plasmid DNA (pDNA) coformulation setup. Two cohorts of eight sheep received either 1 or 4 mg pDNA encoding an ovine anti-cancer embryonic antigen (CEA) monoclonal antibody (mAb; OVAC). Results showed a dose-response with average maximum serum concentrations of respectively 0.3 and 0.7 µg/ml OVAC, 4-6 weeks after IM EP. OVAC was detected in all 16 sheep throughout the 6-week follow-up, and no anti-OVAC antibodies were observed. Another, more exploratory, cohort of two sheep received a 12 mg pOVAC dose. Both animals displayed a similar dose-dependent mAb increase and expression profile in the first two weeks. However, in one animal, an anti-OVAC antibody response led to loss of mAb detection four weeks after IM EP. In the other animal, no anti-drug antibodies were observed. Serum OVAC concentrations peaked at 4.9 µg/ml 6 weeks after IM EP, after which levels gradually decreased but remained detectable around 0.2 to 0.3 µg/ml throughout a 13-month follow-up. In conclusion, using a delivery protocol that is currently employed in clinical Phase 1 studies of DNA-based antibodies, we achieved robust and prolonged in vivo production of anti-cancer DNA-encoded antibody therapeutics in sheep. The learnings from this large-animal model regarding the impact of pDNA dose and host immune response on the expressed mAb pharmacokinetics can contribute to advancing clinical translation.

Assessment of the risk associated with chemical pollution of air environment of sports facilities for children’s health

Introduction. Acute and chronic exposure to chemicals is accompanied by a complex of disorders in the activity of the respiratory, immune and other systems. Purpose is to assess the health risk to children from short-term exposure to pollutants in air of out- and indoor sports facilities. Materials and methods. The air quality of ice arenas, sports halls for martial arts and sports halls in schools was studied using maximum samples; out-door air - according to the average monthly and maximum concentrations registered in 2017-2021. The risks of acute exposure for indoor and outdoor sports facilities are calculated. Results. Against the background of a single excess of the maximum one-time (in gyms) and average monthly (in the atmosphere) concentrations of chemicals, risks to the health of children involved in sports were identified. The maximum share contribution to hazard index (HI) for the respiratory system in the air of the ice arena is made by formaldehyde (58.3%), in school halls - by suspended solids (47.3%). The seasonal dynamics of pollution is revealed, which confirms the importance of thermal power emissions. The maximum Hazard Quotient (HQ) PM10 = 3.1-3.9 is established in winter, and in summer it is 3-4 times lower. The content of PM2.5 in the air is responsible for the extremely high risk in May (HQ = 12.5). The limitation of the results is due to the lack of indoor studies and insufficient knowledge on the impact of acute health effects. Limitations the results are due to the small number of indoor studies and insufficient knowledge about the impact of acute health outcomes. Conclusion. Further study of the short-term effects of indoor and outdoor air pollution from sports facilities is needed.

Analysis of emissions during the combustion of pellets in boiler units

The object of research is the technological process of burning pellets in boilers. Using solid fuel boilers on pellets for heat production, they are trying to reduce dependence on hydrocarbon energy resources. Often such boilers are installed for autonomous heating of schools and other communal facilities. One of the most problematic areas is the analysis of the environmental impact when using pellets as a fuel for municipal boiler houses in urban areas. Boilers operating on solid fuels are characterized by a larger range of pollutants, as well as large values of concentrations emitted through the chimney. In the course of the research, instrumental measurement tools were used, which made it possible to obtain the value of the concentrations of pollutants in the emissions from the chimneys of boilers. In particular, the average maximum concentrations of the main pollutants were: nitrogen dioxide – 271.78 mg/m3, carbon emissions – 1935.44 mg/m3, sulfur dioxin – 13.37 mg/m3, suspended solids, undifferentiated in composition (dust, ash) – 93.2 mg/m3. Using the data of instrumental measurements according to the method of calculating the concentrations of harmful substances in the atmospheric air, a map of the dispersion of emissions was created. Surface concentration fields were plotted on the scatter map, which makes it possible to compare the obtained values with hygienic normative atmospheric air. This makes it possible to determine the distance where the highest value of pollutants from the emission source is recorded. By combining instrumental measurement methods and calculation methods, the volumes and nomenclature of emissions were determined. This made it possible to determine the amount of pollutants per unit mass of burned pellets in the boiler. Using the conducted studies and theoretical calculations for various types of fuel in the production of heat, this will allow assessing their impact on air pollution and reducing the risk of harm to human health.

Honey bee colonies maintain CO2 and temperature regimes in spite of change in hive ventilation characteristics

CO2, a byproduct of respiration, is toxic at high concentrations so regulation of CO2 within the honey bee hive is an important colony function. In this study, we measured hive CO2 concentrations at 1-s intervals while ventilation characteristics of the hive were changed every few days, and we analyzed the data for effects of increased ventilation on colony behavior and thermoregulation. Average CO2 concentrations were significantly higher, by > 200 ppm, when hives had screened bottom boards (higher ventilation) compared to hives with solid bottom boards (lower ventilation) at the same time. Daily CO2 concentration amplitudes, hourly temperature, daily temperature amplitudes, nor hourly hive weight changes were not significantly affected by the changes in hive ventilation. In a second experiment, we found average CO2 concentrations at the top center of the upper hive box, on top of the frames, were significantly lower than concentrations at the center of a solid bottom board underneath frames, which was expected due to the higher density of CO2 relative to air. Bee colonies have been reported to cycle air, with shorter periods of 20 to 150 s and longer periods of 42–80 min, but a periodogram analysis of the CO2 concentration data found no evidence of important CO2 cycle periods other than a strong 24-h period. Bee colonies maintained strong daily cycles of CO2 concentration, with average maximum concentrations > 11,000 ppm, even in conditions of increased ventilation, indicating that managing CO2 concentration is a complex colony behavior.

Screening of pesticides and emerging contaminants in eighteen Greek lakes by using target and non-target HRMS approaches: Occurrence and ecological risk assessment

Lakes, albeit ecosystems of vital importance, are insufficiently investigated with respect to the degradation of water quality due to the organic micropollutants load. As regards Greece, screening of lake waters is scarce and concerns a limited number of contaminants. However, understanding the occurrence of contaminants of emerging concern (CECs) and other micropollutants in lakes is essential to appraise their potential ecotoxicological effects. The aim of this study was to deploy a multiresidue screening approach based on liquid chromatography−high-resolution mass spectrometry (HRMS) to get a first snapshot for >470 target CECs, including pesticides, pharmaceuticals, personal care products (PPCPs), per- and polyfluoroalkyl substances (PFASs), as well as organophosphate flame retardants (OPFRs) in eighteen Greek lakes in Central, Northern and West Northern Greece. The omnipresent compounds were DEET (N,N-diethyl-meta-toluamide), caffeine and TCPP (tris (1-chloro-2-propyl) phosphate). Maximum concentrations varied among the different classes. DEET was detected at a maximum average concentration of >1000 ng/L in Lake Orestiada, while its mean concentration was estimated at 233 ng/L. The maximum total concentrations for pesticides, PPCPs, PFASs, and OPFRs were 5807, 2669, 33.1, and 1214 ng/L, respectively, indicating that Greek lakes are still threatened by the intense agricultural activity. Besides, HRMS enabled a non-target screening by exploiting the rich content of the full-scan raw data, allowing the ‘discovery’ of tentative candidates, such as surfactants, pharmaceuticals, and preservatives among others, without reference standards. The potential ecotoxicity was assessed by both the risk quotient method and ECOSAR (Ecological Structure Activity Relationships) revealing low risk for most of the compounds.

Tumor growth inhibition modeling to support the starting dose for dacomitinib.

Dacomitinib is a second-generation, irreversible EGFR tyrosine kinase inhibitor for first-line treatment of patients with metastatic non-small cell lung cancer and EGFR-activating mutations. A high rate of dose reductions in the pivotal trial led to an observed inverse exposure-response (ER) relationship with the primary end points. Three ER models were developed to determine if the starting dose from the pivotal trial, 45 mg once daily (q.d.) dose, is appropriate: a longitudinal logistic regression model for adverse event-related dose changes, a Claret tumor growth inhibition (TGI) model, and a Cox model for progression-free survival (PFS) based on the TGI model predictions. This analysis included 266 patients taking dacomitinib with a starting dose of 45 mg (N=250) or 30 mg (N=16) q.d. The ER relationships with the time-varying exposure metrics, most recent maximum plasma concentration (Cmax ) and average concentration (Cavg ) from the first dose, were established for the dose reduction and TGI models, respectively. The TGI model characterized the tumor inhibition over time with constant growth rate (kL =0.0012 years-1 ) and highly variable kill rate (kD =1.002 years-1 /[μg/L]θcavg , coefficient of variation [CV]=89%) and drug resistance (λ=14.47 years-1 , CV=96%) leading to prolonged tumor shrinkage. The ER relationship was characterized using an exposure parameter with a power parameterization (θcavg=0.454, p < 0.0001). The Cox model found that baseline tumor size (p=0.0166) and week 8 tumor shrinkage rate (p=0.0726) were the best predictors of PFS. Simulations of dose reductions and drug interruptions on tumor shrinkage over time showed greater and more prolonged tumor shrinkage with a starting dose of 45 mg q.d.

Estimation of chromophoric dissolved organic matter and its controlling factors in Beaufort Sea using mixture density network and Sentinel-3 data

With the warming of the high-latitude regional climate, melting of permafrost, and acceleration of hydrological cycles, the Arctic Ocean (AO) has undergone a series of rapid changes in the past decades. As a dominant optical component of the AO, the variations in chromophoric dissolved organic matter (CDOM) concentration affect the physiological state marine organisms. In this study, machine learning retrieval model based on in situ data and mixture density network (MDN) was developed. Compared to other models, MDN model performed better on test data (R2 = 0.83, and root mean squared error = 0.22 m−1) and was applied to Sentinel-3 OLCI data. Afterward, the spatiotemporal distribution of CDOM during the ice-free (June–September) from 2016 to 2020 in the Beaufort Sea was obtained. CDOM concentration generally exhibited an upward trend. The maximum monthly average CDOM concentration appeared in June and gradually decreased thereafter, reaching its lowest value in September of each year. The maximum value appeared in June 2020 (0.91 m−1), and the minimum value was observed in September 2017 (0.81 m−1). The CDOM concentration nearshore was higher than that in other areas; and gradually decreased from offshore to the open sea. CDOM was highly correlated with salinity (R2 = 0.49) and discharge (R2 = 0.53), and the tight correlation between salinity and CDOM further suggested that terrestrial inputs were the main source of CDOM in the Beaufort Sea. However, sea level pressure contributed to the spatial variations in CDOM. When southerly wind prevailed and wind direction was aligned with the CDOM diffusion direction, the wind accelerated the diffusion of CDOM into the open sea. Meanwhile, seawater was diluted by the sea ice melting, resulting in decrease in CDOM concentration. Herein, this paper proposed a robust and near real-time method for CDOM monitoring and influence factor analysis, which would promote the understanding of AO CDOM budgets.

Ozone Sensitivity Analysis and Control Strategy in Shijiazhuang City in July 2019

The pollution characteristics of surface ozone and its response to meteorological factors were studied based on monitoring in July 2019 in Shijiazhuang City, China. Furthermore, the WRF-CMAQ model coupled with O3 isopleths (EKMA curves) were applied to explore the non-linear response relationship of O3 to precursors VOCs and NOx, aiming to identify a suitable precursor control strategy. The results showed that the days with the maximum daily 8-hour average ozone concentration (MDA8 O3) exceeded the standard by 70.9%. The nonattainment days were usually accompanied by higher temperature, lower relative humidity, and low winds, and the south and southeast winds occurred frequently. The O3 formation was in the strong VOC-limited regime in the urban area of Shijiazhuang, whereas it was in the NOx and VOCs transition regime in suburban areas. As for the urban area, under the condition of single NOx emission reduction, O3 pollution improved when continuous NOx emission reduction was higher than 50% during the nonattainment days. By contrast, during the non-polluted days, O3 concentrations would not rebound when the reduction ratio of NOx and VOCs was higher than 1. In conclusion, VOCs reduction should be the priority for emission reduction plans in urban areas, whereas all different NOx and VOCs ratios led to a decline in O3 concentration in the suburban areas, and a VOCs:NOx of 1:2 was recommended.

Content of some heavy metals in plants of Artemisia gmelinii Web. et Stechm (Transbaikal Territory)

The paper presents research data on the content of chemical elements (Fe, Mn, Ti, Zn, Cu, Pb, Cr, Ni) in a plant Artemisia gmelinii Web. eх Stechm, growing on the territory of the Transbaikal Territory. It has been established that most of the studied elements are concentrated in the aboveground phytomass of the plant. The maximum average concentrations are recorded for iron, manganese and titanium. Only zinc accumulates in the leaves of the studied species. Nutrients chemical elements as copper and nickel are evenly distributed throughout the plant. For copper, zinc and lead, exceed-ances of the maximum permissible concentrations were recorded (for dry vegetables).

Application of the Gaussian Model for Monitoring Scenarios and Estimation of SO2 Atmospheric Emissions in the Salamanca Area, Bajío, Mexico

Population and industrial growth in Mexico’s Bajío region demand greater electricity consumption. The production of electricity from fuel oil has severe implications on climate change and people’s health due to SO2 emissions. This study describes the simulation of eight different scenarios for SO2 pollutant dispersion. It takes into account distance, geoenvironmental parameters, wind, terrain roughness, and Pasquill–Gifford–Turner atmospheric stability and categories of dispersion based on technical information about SO2 concentration from stacks and from one of the atmospheric monitoring stations in Salamanca city. Its transverse character, its usefulness for modeling, and epidemiological, meteorological, and fluid dynamics studies, as suggested by the models approved by the Environmental Protection Agency (EPA), show a maximum average concentration of 399 µg/m3, at an average distance of 1800 m. The best result comparison in the scenarios was scenery 8. Maximum nocturnal dispersion was shown at a wind speed of 8.4 m/s, and an SO2 concentration of 280 µg/m3 for stack 4, an atypical situation due to the geography of the city. From the validation process, a relative error of 14.7 % was obtained, which indicates the reliability of the applied Gaussian model. Regarding the mathematical solution of the model, this represents a reliable and low-cost tool that can help improve air quality management, the location or relocation of atmospheric monitoring stations, and migration from the use of fossil fuels to environmentally friendly fuels.

Modeling the impact of reducing sulfur content of liquid fuels consumed by power plants on the air quality of Kuwait using AERMOD

As part of Kuwait’s plan to meet the country’s long-term sustainability goals, a new refinery is being constructed with an objective of desulfurizing crude oil (CO) and heavy fuel oil (HFO) to a low sulfur content, S% (approximately 1% by mass). Since Kuwait’s electric power system relies heavily on CO and HFO for electricity generation, the air quality impacts of this change in sulfur content should be investigated. In this work, three scenarios were examined and compared to the base case. The hourly SO2 emissions of each scenario were simulated using an air quality model (AERMOD) to determine the spatial and temporal SO2 dispersion for the year 2014. The three scenarios were developed based on lowering the sulfur content to 1% for HFO only, CO only, and both HFO and CO. The study results indicated that the annual SO2 emissions were reduced by 75.6%, 12.5% and 82.7% for the first, second and third scenarios, respectively, compared to the base case scenario. The daily averages of SO2 emissions of the first, second and third scenario were 57.7%, 12.4% and 70.1% lower, respectively, compared to the base case. The reductions in the maximum region wide one-hour average SO2 concentrations reached 47.4%, 24% and 54.1% for the first, second and third scenarios, respectively, compared to the base case. The numbers of hourly SO2 exceedances were reduced by about 94%, 54% and 100% for the first, second and third scenarios, respectively, compared to the base case (7361 hourly SO2 exceedances). The results of this analysis show the benefits of reducing the sulfur content of CO and HFO as mitigation strategy to reduce high ambient SO2 concentrations.

Study on the effect of vehicular pollution on the ambient concentrations of particulate matter and carbon dioxide in Srinagar City.

The present study was carried out to monitor the ambient concentrations of particulate matter and carbon dioxide caused by vehicular pollution in Srinagar City of Jammu and Kashmir, India, for a period of 12 months from June 2019 to May 2020 as the major contributions in these areas are due to vehicular movement. Out of five, four locations (viz. Dalgate, Jehangir Chowk, Parimpora and Pantha Chowk) had highest traffic density in the city and the fifth location (Shalimar) had low traffic volume. The sampling was done on every fortnight using AEROCET 831—aerosol mass monitor and CDM 901—CO2 monitor with each sampling being carried out three times a day, i.e. morning (9:00 am–10:30 am), afternoon (1:00 pm–2:30 pm) and evening (4:30 pm–6:00 pm) with three replications at each site based on the peak traffic hours. The results show that during the whole period, average PM1 concentrations ranged from 15.10 to 108.9 µg/m3, PM2.5 (28.70–577.50 µg/m3), PM4 (44.50–780.87 µg/m3), PM10 (57.13–1225.53 µg/m3), total suspended particulates (77.77–1410.27 µg/m3) and CO2 (332.4–655.0 ppm). The average concentrations of these parameters showed that the maximum PM1 concentration was found at Dalgate (53.77 µg/m3) and PM2.5 had its maximum average concentration at Jehangir Chowk (140.13 µg/m3). Other parameters like PM4, PM10, TSP and CO2 had a maximum average values at Jehangir Chowk (240.23 µg/m3, 633.40 µg/m3, 853.50 µg/m3 and 533.20 ppm, respectively). The pollution load was observed to be maximum during winter season followed by autumn, summer and spring. The lowest concentration of all pollutants except CO2 was observed in April 2020 and this might be due to COVID-19 lockdown observed in the country during the same period.

Field gamma ray spectrometry as a diagnostic tool for the assessment of hypothetical melt rocks from the Maâdna structure (Talemzane, Algeria): Implications for the crater formation process

AbstractAmong all geophysical methods, gamma ray spectrometry is not widely used in impact cratering studies, despite its efficiency in the investigation of physical/chemical changes in rocks. The application of gamma ray spectrometry method to data from the Maâdna crater is aimed at detection and verification of the presumed impact‐derived melt rocks or breccias, as well as discussing its implications on process of formation. The resulting information also demonstrates the potential of these specific data regarding our general understanding of impact cratering, while a few case studies have been reported in the literature to date within the impact community. Maâdna crater is dated at 2.6–3.1 Ma of ~1.7 km and is emplaced in Upper‐Cretaceous to Eocene limestones of the northern part of the Algerian Saharan platform. Although originally accepted as an impact crater, its origin is still controversial. Several thousands of field measurements were taken using a field portable gamma ray spectrometer. The measurements can be equivalently expressed by up to about 42 km footpath recordings in real‐time ground acquisitions, covering the entire structure and surrounding areas beyond the crater edge. The collected data included the total count (Tc) and the concentrations of the radionuclides calculated in wt% for K and in ppm for U and Th. The spectra rates recorded inside and outside the crater did not exceed the maximum average concentrations corresponding to 75.3 Cps, 4.94 ppm, 10.5 ppm, and 1.79 wt% for Tc, U, Th, and K, respectively. The database was processed using various gridding data methods, from which the minimum curvature was adopted as it provides a powerful visualization and interpretation of the anomalous distribution of radioactive elements and their corresponding ratios maps. In addition, an improved statistical analysis was carried out in order to extract a maximum of information about the radiometric response of each rock unit. This analysis consisted of a series of multiple linear regression, mean differencing, Q–Q (quantile–quantile) plots, and ternary mapping. Maps and plots of various models allowed us to examine the background variability in the distribution of K, Th, and U concentrations at the surface of the three distinctive litho‐type zones in the surveyed area, which are the central part, the crater edge, and the outside of the crater including the wadi deposits. Observed results of different radiometric responses clearly reflect the effect of various lithological units, especially in the areas with high K concentration. Note that this positive K‐anomaly has been observed in recent deposits that fill the Maâdna depression or external wadi beds. In contrast, the surrounding limestone rocks showed lower levels of radioelement concentrations. Relevant similarities found between the radiometric signatures of the Neogene formations inside and outside the crater can be considered as a strong argument to exclude preferential radionuclides enrichment caused by an impact event. Consequently, the natural origin of radioactive sources can be easily explained. Compared to other radiometric signatures documented on proven impact structures, the Maâdna structure has been notably discussed in the context of a diapiric hypothesis rather than a meteoritic one. Moreover, the methods used here contribute to our knowledge of the regional sedimentary history in terms of natural radioactivity.

Multi-Media Occurrence of Antibiotics and Antibiotic Resistance Genes in East Dongting Lake

With the extensive use of antibiotics, antibiotics and their induced resistance genes (ARGs) have become new types of pollutants widely distributed in a variety of environmental media. The contamination of antibiotics and ARGs occurring in important living and agricultural regions has aroused wide concern worldwide, especially in lake basins. The Dongting Lake basin is one of the important aquaculture and livestock areas in China, which is accompanied by a large amount of antibiotic use and discharge. However, the occurrence characteristics of antibiotics and ARGs in a multi-environment medium are still unclear. In this study, surface water and sediment samples in East Dongting Lake were collected by season, antibiotics and ARGs were quantitatively analyzed, and the risk quotient method was used to evaluate the ecological risk of antibiotics in surface water. 1) The concentration of antibiotics in the surface water of East Dongting Lake ranged from ND to 943.49 ng/L, with the maximum average concentration of 20.92 ng/L in spring. The concentration of antibiotics in sediments ranged from ND to 177.43 ng/g, with the maximum average concentration of 16.38 ng/g in fall. Ofloxacin (OFL) and sulfamethoxazole (SMX) were the main antibiotic pollutants in East Dongting Lake Basin. 2) sul1 and sul2 were the dominant ARGs in East Dongting Lake Basin. For spatial change, the total abundance of ARGs upstream was higher than that downstream. For seasonal change, the surface water and sediment were characterized by spring &amp;gt; summer &amp;gt; fall. 3) OFL and sulfamethoxazole might pose a significant high risk to aquatic organisms both in three seasons, and the ecological risk of antibiotics in East Dongting Lake is more significant at low temperatures than high. This study could provide important data information of the occurrence and concentration of antibiotics and ARGs in East Dongting Lake Basin.

A case study of the westward transport of Chorophyll-a entrained by ocean eddies during a tropical cyclone

During the passage of tropical cyclone (TC) ARB O1, a westward transport of Chlorophyll-a (Chl-a) enhancement was identified south of the Indian Peninsula. The features and underlying dynamics were investigated with high-resolution satellite remote sensing, reanalysis, and Argo buoy data. From January 12 to January 19, 2006, the phytoplankton bloom propagated westward with two ocean anticyclonic eddies, which were enhanced after the passage of the TC. The surface average maximum Chl-a concentration with an inertia period of approximately 4–5 days occurred in the four boxes. The maximum average concentration of Chl-a on January 16 (21) was 0.4 mg•m−3 (0.53 mg•m−3) in Box B, which was caused by a cyclonic eddy and Ekman pumping triggered by the TC (horizontal current transport). However, the maximum average concentration of Chl-a was 0.32 mg•m−3 in Box D, which was caused by an anticyclonic eddy and Ekman pumping triggered by the TC. After passage of the TC, the mixing layer deepened, and the upper ocean stratification weakened, which promoted an uplift of phytoplankton from the deeper layer to the upper layer. In addition to horizontal current transport, westward phytoplankton transport was produced under the joint influence of eddy entrainment and Ekman pumping triggered by the TC. This study can aid with assessing the biological responses of future typhoons.

Characteristics of Secondary PM2.5 Under Different Photochemical Reactivity Backgrounds in the Pearl River Delta Region

With the increasing control of air pollution, the levels of atmospheric particulates in the Pearl River Delta (PRD) region are gradually decreasing. However, ozone pollution has become more and more serious, and the problem of secondary aerosol pollution caused by photochemical reactions cannot be ignored. Based on the observation data of environmental and meteorological stations in the nine cities of the PRD during 2019, we investigated the variations of secondary PM2.5 (PM2.5-sec) in the PRD under different photochemical reactivity backgrounds. It was shown that the photochemical reactivities appeared more significant in the central and western areas than those in the eastern areas of the PRD and appeared more significant in inland areas than those in coastal areas. The days of moderate and high photochemical reactivities mainly appeared from August to November. PM2.5-sec concentrations were the highest in autumn, during which the regional discrepancies appeared most significantly with the highest levels in the southern areas. With the enhancement of the photochemical reactivity background, the PM2.5-sec level at each station increased significantly, which appeared significantly higher in coastal areas than in inland areas. Both PM2.5-sec and ozone concentrations showed single-peak variations, which appeared higher in the daytime than at night with the peak occurring at about 15:00. For each pollutant, the average maximum concentration appeared higher for polluted stations than for clean ones, indicating that the atmospheric oxidation background was conducive to the formation of PM2.5-sec.

Level of Contamination of Fishponds Water in Pesticide Residues and Metallic Trace Elements (Pb, Cd, As, Hg): Case of Fishponds of ZEPREGUHE (Daloa, C&amp;amp;ocirc;te d’Ivoire)

Fishponds waters intended to satisfy the nutritional needs of the populations in terms of supply of fish resources are strongly and unfortunately exposed to the mobility and dispersion of metallic trace elements (TMEs) or to the persistence in the environment and in the form of pesticide residues from human activities. The objective of this work is to evaluate, on the one hand, the levels of identified pesticide residues and, on the other hand, those of researched TMEs (lead, cadmium, mercury and arsenic) in the waters of ponds used for fish farming in Zépréguhé, a locality located 9 km from the town of Daloa in the centre-west of Côte d’Ivoire. The dosage of the samples carried out by means of a gas chromatograph coupled to a mass spectrometer (GC/MS) made it possible to detect nine (9) pesticide molecules, including eight (8) organochlorines and a single molecule from the pyrethroid family, obtained from the detection limit of 0.006 μg/L and the quantification limit of 0.018 μg/L. The maximum average concentration was obtained with α-endosulfan for a content reaching 0.8038 μg/L and well above the maximum admissible concentration of 0.1 μg/L. The TMEs were quantified using an atomic absorption spectrophotometer (AAS). Arsenic is the most abundant metal with an average concentration of 9.497 μg/L. With the exception of lead, these measured levels are above the acceptable limit values for freshwater. This study showed that human activities such as the use of fertilisers and plant protection products in plantations, sand extraction and road traffic have a negative impact on the quality of the water in ponds used for fish breeding.

Chemical and Microbiological Air Quality in a Municipal Solid Waste Landfill and Its Surroundings, in South-Eastern Romania

The aim of this study was to assess the microbiological and chemical air quality in a municipal solid waste landfill and its inhabited surroundings, in a particular context in which Romania struggles with the incapacity to comply with its environmental commitments. The research was conducted on a landfill near the capital Bucharest between November 2018 and September 2019. To evaluate the chemical (oxygen, carbon dioxide, methane, hydrogen sulfide, ammonia and carbon monoxide–MX6 iBrid™ Détector multigas) and microbiological (airborne bacteria and fungi–aspiration method) parameters, eight sampling points were established, located both on the perimeter of the landfill and within its surroundings. CO and CH4 were not detected in any of the sampling points, during the study period; O2 was in normal values 20.09–21.05%; CO2 had a maximum average concentration of 620 ± 215; H2S had values between 0.1 and 5.0 ppm only in the sampling points inside the landfill; NH3 was present only once in a single sampling point with values between 1.0 and 3.0 ppm. The microbiological results provide an overview of the total plate count and total fungal count, with no significant differences between the level of contamination inside the landfill and within its surroundings (p &gt; 0.05). Ten bacterial species and fungi from six genera have been identified. It was also found that the number of microorganisms in the air was significantly lower during the winter, spring and early summer months compared with the late summer and autumn months (p &lt; 0.05).

Eber Gölü’nde (Türkiye) su, sediment ve Carassius gibelio (Bloch, 1782) dokularında ağır metal birikimi

In this research, in order to observe the seasonal change between April 2014 and February 2015, heavy metal contents in the water, sediment and the Carassius gibelio (Bloch, 1782) tissues (muscle, gill and liver) growing in Eber Lake were determined. The obtained results showed that trace elements were founded in water, sediment and fish tissues. Among the average annual concentrations of water samples, the highest concentration was found for Mn (0.1584 mg/L) element and the lowest concentration was found for Pb element in the spring season. the maximum Average annual concentration was calculated for Mn (0.1584 mg/L, Spring) and the minimum was determined for Pb in water. In the sediment, Fe (16245.84 mg/kg, Spring) was found to be maximum and Co was the minimum. In fish, the highest concentrations were found in liver (Mo, Ni, Pb, Co, Cu, Fe), while the lowest concentrations were found in gill (Mn, Zn) and muscle (Cd, Cr, Se) tissues While the highest heavy metal concentrations were observed in the sediment, the minimum was found in the fish tissues (the ranking was the following; liver, gill and muscle). It was concluded that the heavy metal levels measured in the Lake Eber have no risk to the environment and to the public health.