February Concentrations Research Articles

Concentrations of Sulfur Dioxide in Urban Air Space Above North Central Texas, United States

Hourly average sulfur dioxide concentrations in February and August 2022 were compiled, graphed, and evaluated for five air monitoring stations in north central Texas. The stations occupy the urban core and periphery of the Dallas-Fort Worth metropolitan area. Concentration time series were evaluated relative to stationary sources of sulfur dioxide, the urban core, and shifting wind patterns. Nine large sources emitting more than 100 tons of sulfur dioxide per year were identified in the study area, as were sixty additional facilities emitting between one and ninety-nine tons per year. The highest emitter, an electric power station, produced 4,921 tons of sulfur dioxide per year in 2021. Overall, sulfur dioxide concentrations were low, but periodically breached design standards downwind of large emitters. Hourly average sulfur dioxide concentrations ranged from a minimum of less than 0.1 parts per billion (ppb) at all monitoring stations to a maximum of 170.5 ppb at a station located approximately 1 km away from a mineral processing facility. However, monitoring stations located 2 km to 3 km away from, and periodically downwind of, other large emitters had much lower concentration spikes. This study (1) shows the importance of stationary sources, as opposed to lengthy transport and extensive regional mixing, on sulfur dioxide concentrations in urban complexes; and (2) a need for source-oriented monitors to effectively document sulfur dioxide concentrations in urban air space.

Assessment of atmospheric pollution by oxygenated and nitrated derivatives of polycyclic aromatic hydrocarbons in two regions of the Czech Republic

In this study, a method for monitoring 16 representatives of nitrated polycyclic aromatic hydrocarbons (nitro-PAHs) and six oxygenated polycyclic aromatic hydrocarbons (oxy-PAHs) in airborne particulate matter (PM) was developed and validated. Soxhlet extraction, followed by solid phase extraction (SPE) on silica, was used to isolate the target compounds. Instrumental analysis was performed by gas chromatography coupled with (tandem) mass spectrometry (GC-MS(/MS)) operated in electron impact (EI) and negative ion chemical ionization (NICI) modes. GC-EI-MS/MS was selected for further experiments due to its higher selectivity of measurement and ability to measure derivatives simultaneously with 20 commonly analyzed PAHs (EU + US EPA priority list). This is the first study documenting the simultaneous analysis of OPAHs, NPAHs, and parent PAHs in a single run. This analysis strategy was successfully validated at two concentration levels of artificial contamination, i.e., 0.8 and 4 ng per filter, with recoveries in the 70–104% range and less than 23% repeatability. The newly developed method was used for the analysis of 45 air samples from two cities in the Czech Republic, namely Ceske Budejovice and Most (a place with heavy industry), and two sampling seasons (February vs. May 2017). Five representatives were found in all samples from the oxy-PAH group, with 9,10-anthraquinone (9,10-ANTQ) being the most abundant (0.010–2.49 ng m−3 air). Three major nitro-PAHs, namely 9-nitroanthracene (9-nANT), 2-nitrofluoranthene (2-nFA), and 1-nitropyrene (1-nPYR), were found in 89%, 96%, and 33% of the samples, respectively, found in concentration ranges of <0.60–902, <0.60–276, and <0.60–117 pg m−3 air. Slightly higher levels of oxy- and nitro-PAHs were found in Ceske Budejovice compared to Most, but the difference was not statistically significant (p-value >0.05). A statistically significant difference was observed between February and May, where the concentrations in February were up to 20 and 50 times higher for individual oxy- and nitro-PAHs, respectively, in both regions. The diagnostic ratio 2-nFA/1-nPYR >5 showed that indirect emissions were the primary nitro-PAH source in Most of nitro-PAHs in Most and in both sampling campaigns. In Ceske Budejovice, the opposite trend was observed in winter, i.e. 2-nFA/1-nPYR <5, indicating direct emissions as the main source. In summary, direct emissions of OPAHs and NPAHs originate from fossil (transportation-related) and solid fuel (heating-related) combustion. In contrast, indirect emissions are related to atmospheric reactions of PAHs with OH radicals (spring, winter) and NO3 radicals (winter). The total TEQB[a]P was higher in winter than spring, with higher inhalation cancer risk.

Chemical fingerprints and source resolution of atmospheric fine particles in an industrial harbor based on one-year intermittent field sampling data

This study investigated the spatiotemporal variation, chemical characteristics, and source resolution of PM2.5 in an East Asian seaport adjacent to industrial complex and urban area. Three representative harbor sites were selected to simultaneously sample 24-h PM2.5 once every 13 days in four seasons. A significant seasonal variation was observed with the highest and the lowest PM2.5 concentration in February (winter) and May (summer), respectively. High contribution of secondary inorganic aerosols (SIAs) showed that SO2 and NOx emitted from neighboring combustion sources burning coal and heavy fuel oil (HFO) were the major precursors forming secondary inorganic PM2.5. High ratios of V/Ni and V/Cu were observed in summer (June~August) since the prevailing west and southwest winds from outer port carried ship emissions to inter port. The correlation of chemical fingerprints (V, Ni, V/Ni, Zn, nss-SO42−, OC) and the number of ships were high at the Zhung-He Site and moderate at the Qi-Ho Site. The Cl−, Na+, V, Ni, nss-SO42−, OC, and V/Ni of PM2.5 were co-influenced by ship missions and oceanic spray in the Kaohsiung Harbor. The influences were relatively higher for winds blown from the harbor areas than those blown from the industrial areas. Oppositely, the Fe, Mn, Cr, Cu, Ca, Zn, and Al in PM2.5 were higher for winds blown from the industrial areas than those from the harbor areas. The CMB receptor modelling resolved that the major sources of PM2.5 were industrial missions, secondary aerosols, mobile sources, ship emissions, oceanic spray, fugitive dust, biomass burning, and organic carbon. Similar to Busan (South Korea), Brindisi (Italy), Lampedusa (Italy), and Barcelona (Spain), the contributions of ship emissions in the Kaohsiung Harbor were in the range of 7.4–7.8 %. Meanwhile, Kaohsiung Harbor was highly influenced by emissions from industrial areas and urban areas.

Long-term variations and comparison of aerosol optical properties based on MODIS and ground-based data in Thailand

Comparison and analysis of Moderate Resolution Imaging Spectroradiometer (MODIS), Aerosol Robotic Network (AERONET), and SKYNET aerosol optical depth (AOD) products were investigated at four AERONET and two SKYNET stations in Thailand from 2006 to 2020. AERONET Level 2.0 and MODIS Deep Blue (DB) Collection 6.1 data were applied. Aqua and Terra MODIS AODs (satellite AODs) were compared to AERONET and SKYNET AODs (ground based AODs). Ground-based and satellite AODs were in good agreement, giving a high correlation (R2 = 0.75) in Ubon Ratchathani, associated with biomass burning. The long-term trend in AOD was analyzed. Both satellite and ground based AODs demonstrate increasing trends in AOD over Thailand associated with the urbanized area and traffic congestion. Aerosol particles are categorized into dust, sea salt, and biomass burning, containing fine and coarse modes. A variation between satellite data measurements depended on surface reflectances, such as the large water body surrounding (Songkhla) and the impact of surface albedo (Chiang Mai). Higher AOD values were observed between February to April. In addition, meteorological parameters are directly related to aerosol concentrations, while no significant connection could be developed in the observed values between Angstrom exponent (AE) and Meteorological parameters. Meteorological parameters and temperature inversion more influenced AOD concentrations in February. Nevertheless, the hypothesis showed 95% confidence interval of AODs retrieved from satellite data fell within the confidence range. Therefore, satellite aerosol products are sufficiently accurate for estimating aerosol climatology.

Study of emitted gases from incinerator of Al-Sadr hospital in Najaf city

Abstract Medical waste incinerator of Al-Sadar hospital in Najaf city is one of the environmental pollution sources in the city due to reasons related to the quantity and quality of gases emitted from it, so this study aims to estimate environmental damage by determining the concentrations of some of these emitted gases. The study is concerned with determining the concentrations of six gases over five months (November 2013–March 2014), these gases were oxygen (O2), silane (SiH4), hydrogen (H2), sulfur dioxide (SO2), nitrogen dioxide (NO2), and hydrogen sulfide (H2S), in addition to studying some weather factors such as wind speed and temperature that affect on the concentrations of the gaseous pollutants. It is found that the study area suffers from pollution with SO2 gas, which is one of the main standard pollutants for assessing polluted areas, where the mean of gas concentration during the study period was 0.205 [ppm] and thus exceeded the permissible limits. Moreover, some of the studied gases (like NO2 and H2S) have concentration close to the upper limit of the standards, where NO2 gas concentration in December and January were 0.17 [ppm] and 0.2 [ppm], respectively, and H2S gas concentrations in February and March were 3.5 [ppm] and 4.4 [ppm], respectively, which poses a threat to public health and other elements of the environment, which confirms the existence of an air pollution problem that the study area and the nearby areas suffer from.

Determination of phytoplankton in water samples, algal biotoxins, microbiological parameters and microplastics in Mediterranean mussels (Mytilus galloprovincialis Lamarck, 1819) from an experimental pilot farm in the Calich Lagoon (Sardinia, Italy).

The aims of this paper were to collect and analyse preliminary data of phytoplankton in the water, biotoxins, Escherichia coli, Salmonella spp., Vibrio spp. and microplastic eventually present in farmed mussels, and to acquire information about the production capability from an experimental pilot farm of the Calich Lagoon. Two sampling sessions were carried out, in February and in May 2019, also monitoring the water condition (pH, temperature, salinity, dissolved oxygen, chlorophyll a). No potentially toxic algae were detected, and moreover no biotoxins (Paralytic Shellfish Poison, Diarrheic Shellfish Poison, Amnesic Shellfish Poison) were found in mussels. E.coli was present with the highest concentration in February (16000 MPN/100g e.p.). Salmonella and Vibrio spp. have not been detected. Almost a microplastic per grams was found, mainly fiber of different colours. Further studies, carried out for several months, will allow to better understand the possible problems related to the production of mussels in a lagoon not yet classified as a shellfish production area.

Quantify the role of anthropogenic emission and meteorology on air pollution using machine learning approach: A case study of PM2.5 during the COVID-19 outbreak in Hubei Province, China

Air pollution is becoming serious in developing country, and how to quantify the role of local emission and/or meteorological factors is very important for government to implement policy to control pollution. Here, we use a random forest model, a machine learning (ML) approach, combined with a de-weather method to analyze the PM2.5 level during the COVID-19 outbreak in Hubei Province. The results show that changes in anthropogenic emissions have reduced PM2.5 concentrations in February and March 2020 by about 33.3% compared to the same period in 2019, while changes in meteorological conditions have increased PM2.5 concentrations by about 8.8%. Moreover, the impact of meteorological conditions is more significant in the central region, which is likely to be related to regional transport. After excluding the contribution of meteorological conditions, the PM2.5 concentration in Hubei Province in February and March 2020 is lower than the secondary standard of China (35 μ g/m3). Our estimates also indicate that under similar meteorological conditions as in February and March 2019, an emission reduction intensity equivalent to about 48% of the emission reduction intensity during the lockdown may bring the annual average PM2.5 concentration to the standard (35 μ g/m3). Our study shows that machine learning is a powerful tool to quantify the influencing factors of PM2.5, and the results further emphasize the need for scientific emission reduction as well as joint regional control measures in future.

Monthly Variation in the Macromolecular Composition of Phytoplankton Communities at Jang Bogo Station, Terra Nova Bay, Ross Sea.

Organic carbon fixed by photosynthesis of phytoplankton during the polar growing period could be important for their survival and consumers during the long polar night. Differences in biochemical traits of phytoplankton between ice-free and polar night periods were investigated in biweekly water samples obtained at the Korean “Jang Bogo Station” located in Terra Nova Bay, Antarctica. The average concentration of total Chl-a from phytoplankton dominated by micro-sized species from the entire sampling period was 0.32 μg L–1 (SD = ± 0.88 μg L–1), with the highest concentration of 4.29 μg L–1 in February and the lowest concentration of 0.01 μg L–1 during the ice-covered polar night (April–October) in 2015. The highest protein concentration coincided with the peak Chl-a concentration in February and decreased rapidly relative to the carbohydrate and lipid concentrations in the early part of polar night. Among the different biochemical components, carbohydrates were the predominant constituent, accounting for 69% (SD = ± 14%) of the total particulate organic matter (POM) during the entire study period. The carbohydrate contributions to the total POM markedly increased from 39 ± 8% during the ice-free period to 73 ± 9% during the polar night period. In comparison, while we found a significant negative correlation (r2 = 0.92, p < 0.01) between protein contributions and carbohydrate contributions, lipid contributions did not show any particular trend with relatively small temporal variations during the entire observation period. The substantial decrease in the average weight ratio of proteins to carbohydrates from the ice-free period (mean ± SD = 1.0 ± 0.3) to the ice-covered period (mean ± SD = 0.1 ± 0.1) indicates a preferential loss of nitrogen-based proteins compared to carbohydrates during the polar night period. Overall, the average food material (FM) concentration and calorific contents of FM in this study were within the range reported previously from the Southern Ocean. The results from this study may serve as important background data for long-term monitoring of the regional and interannual variations in the physiological state and biochemical compositions of phytoplankton resulting from future climate change in Antarctica.

Behavior of the Average Concentrations As Well As Their PM10 and PM2.5 Variability in the Metropolitan Area of Lima, Peru: Case Study February and July 2016

This research focused on analyzing the behavior of the hourly average concentrations of PM10 and PM2.5 in relation to vehicular traffic, as well as the effect of relative humidity on these concentrations. Measurements of hourly particulate matter concentrations were recorded by the National Meteorology and Hydrology Service of Peru (SENAMHI) at five surface air quality stations. The profiles of PM10 concentrations are related to traffic behavior, showing high levels of concentrations at peak hours, while the PM2.5 profiles are flatter and better related to traffic in February (summer). The decrease in relative humidity between 80 to 65% in the mornings has a greater effect on the increase in PM10 and PM2.5 concentrations in February than in July (winter), and the increase in relative humidity between 65 to 80 % in the afternoon, it has a greater effect on the decrease in the concentration of PM2.5 in February than in July. The air quality in the north (PPD and CRB stations) and east (SJL station) of the Metropolitan Area of Lima (MAL) are the most polluted. The factors that relate PM10 concentrations with the Peruvian standard in February at these stations were 2.79, 1.78 and 1.26, and in July 2.74, 1.28 and 1.36 respectively. The highest and lowest variability of PM10 and PM2.5 in February and July occurred in the northern area (PPD and SMP stations).

Reconstruction of Sea Ice Concentration in Northern Baffin Bay Using Deuterium Excess in a Coastal Ice Core From the Northwestern Greenland Ice Sheet

AbstractVariations in the conditions of sea ice in the northern part of Baffin Bay and North Open Water polynya influence human activity in northwestern Greenland through oceanic circulation and heat balance between air and sea. To evaluate the impact of variations in sea ice conditions on the surrounding environment, it is important to understand the mechanism of sea ice variations over long periods. In this study, we estimated the age of the SIGMA‐A ice core collected northwestern Greenland Ice Sheet and researched the relationship between annual or seasonal deuterium excess (d‐excess) and seasonal sea ice concentration. We found that a temporal variation in the spring d‐excess in the ice core negatively correlated significantly with that of sea ice concentration in February–April in northern Baffin Bay from 1979–2005 (r = −0.61,p &lt; 0.001). Using this relationship, we reconstructed the temporal variations in sea ice concentrations for 100 years from the ice core drilled in the northwestern Greenland Ice Sheet. The sea ice concentration in the early twentieth century was lower than that in the present. The decrease in sea ice concentration was consistent with analytical results for marine sediments obtained from Baffin Bay. We also suggested that the sea ice concentration was controlled by atmospheric conditions from the 1920s to 1940s based on examinations of correlations with the North Atlantic Oscillation index and air temperature in Ilulissat and by oceanographic conditions from 1945–1955, 1959–1969, and 1982–1992 based on the Atlantic Multidecadal Oscillation index and meridional heat transport to western Greenland.

Spatial-temporal management of nitrogen and carbon on the peach tree (Prunus persicae L. Batsch.)

In perennial plants, the management of nitrogen (N) and carbon (C) is crucial to their durability, and studies encompassing an integrative viewpoint on the dynamics, location and form of the reserves are still missing. The carbon and nitrogen components were measured from September to May in peach trees which received two different levels of N fertilisation (control and limited). Significant differences were observed in the N and non-structural carbon concentrations regarding the organs, locations, time and fertilisation level. During the autumn, N and C accumulate at all levels of the tree and are sharply remobilised for the spring growth resumption. Amino acids (AA), especially arginine, appear to be the main form of storage of N. More present in roots, short branches and apices, the AA reach their maximum concentration in February and drop sharply with bud development. The remobilisation of the AA is initially induced in the branches close to the aboveground plant parts structures in formation, and before the contribution of the roots pool. The non-structural carbon (starch, soluble sugars, and organic acids) also accumulate during the autumn. No major differences are observed in the position and the size of the branches. The starch present in the root is the main form of carbon reserve of the peach tree. The starch stocks decline very early in November and are then gradually restored while the tree becomes autotrophic in the spring. The deprivation of N essentially caused a significant decrease in the stocks of AA and erased the differences in concentrations found in relation to the typology of branches. So the tree modified its N management strategy in response to the fertilisation level. The concentration of arginine, the main amino acid present in the bark or in the roots, appears as a relevant marker of its N status.

Rapid increase in contaminant burdens following loss of body condition in canvasbacks (Aythya valisineria) overwintering on the Lake St. Clair region of the Great Lakes

Overwintering canvasbacks were collected in the Lake St. Clair region of the Great Lakes in the winter of 2008/09 and livers were analyzed for organochlorines, mercury (Hg), and selenium (Se). We found dramatic increases in hepatic concentrations of Hg, Se, sum PCBs, p,p’-DDE, and other organochlorines in canvasbacks in which concentrations in February were greater than concentrations in November when overwintering ducks arrived in the study area. Increases in contaminant burdens were generally greatest between December and January which also coincided with the period when ducks from Lake St. Clair (LSC) moved following freeze-up of the Lake to forage on the St. Clair River (SCR), an area of known historic contamination, and upstream of LSC. Body condition estimated using body metrics and measured using lipid reserves (after controlling for body size) increased in LSC ducks but subsequently decreased in SCR ducks. This rapid loss of body condition through loss of lipid reserves was one factor likely driving the dramatic increase in contaminant burdens and particularly for organochlorines which were inversely related to body condition in SCR ducks. Increased exposure due to foraging in closer proximity to contaminant sources and changes in diet associated with the movement of ducks may have also contributed to temporal trends. Concentrations overall were below those associated with toxicity with the exception of Se for which 30% of ducks exceeded the Se threshold that is considered elevated and one duck exceeded the threshold associated with possible toxicity. Fitness consequences of reduced lipid reserves include reduced survival, delayed migration, reduced breeding propensity, and transfer of contaminant burdens to eggs. Food availability, ice cover, and movements of canvasbacks are additional factors influencing contaminant accumulation and lipid reserves in waterfowl utilizing this important wintering location.

Assessment of carbon monoxide concentration in indoor/outdoor air of Sarayan city, Khorasan Province of Iran.

Nowadays, air pollution by humans is considered a serious problem. One of the main sources of air pollution is carbon monoxide which is called the silent killer. With the increasing rate of population growth in Iran and subsequent acceleration of vehicle and fossil fuel usage, the mortality rate of carbon monoxide has increased. The aim of this study is assessment of the concentration of carbon monoxide in indoor and outdoor air of Sarayan city, Khorasan Province of Iran. In this descriptive-analytic study, the air condition of a residential area and outdoor environment of Sarayan city has been monitored for determining the carbon monoxide concentration during a 3-month period from January to March 2017. Overall, 25 stations with uniform distribution were located in the city. Fifty samples were taken monthly and by considering 3-month period, a total of 150 samples were gathered. The samples were taken in kitchens between 11a.m. and 3p.m., and by considering the respiratory height of the human body, the carbon monoxide meters (TES model, Taiwan) were placed at a height of 75-150cm. The descriptive statistics were presented after entering data into SPSS-16, and, by applying Mann-Whitney and Kruskal-Wallis tests in the case of α = 0.05, the data were analyzed. The average concentrations of carbon monoxide in indoor and outdoor environments were 0.84 ± 3.21ppm and 0.27 ± 0.92ppm, respectively. The maximum carbon monoxide concentration in February in an outdoor environment was 6ppm (station no. 4) and the least one was 0ppm. In March, for an indoor area, the maximum carbon monoxide concentration was 41pm for station no. 11. The indoor-to-outdoor (I-to-O) ratio in March was higher than other months, and in January, was less than others. The study reveals that the indoor and outdoor carbon monoxide indices of Sarayan city are at acceptable levels.

Behavior of sulfate on the sea surface during its transport from Eastern China to South Korea

This study investigates the production/loss of sulfate on the sea surface during its transport from Eastern China to South Korea (Korea). We use the Community Multi-scale Air Quality (CMAQ) model to simulate sulfate concentrations in February 2015 and to examine the changes in them. Results of the CMAQ simulation show high sulfate concentrations over the sea surface areas between Eastern China and Korea despite nearly zero emissions. Their concentrations gradually increased (from 0.371 to 0.581㎍/m3/h) as they passed through the East China Sea, the Yellow Sea, and the Korea Strait. The results from a quantitative analysis using the integrated process rate (IPR) in CMAQ suggest that increasing sulfate concentrations during the transport was mainly attributable to chemical sulfate productions by the aerosol process (up to 0.866㎍/m3/h) and vertical transport (up to 0.994㎍/m3/h) of chemically produced sulfate, resulting from vertical momentum transport caused by vertical wind shear and temperature gradient. The results of the sulfur tracking model (STM) in CMAQ verify that the OH + SO2 → H2SO4 + HO2 reaction was the largest contributor (82.31%) to the production of sulfate over the sea surface areas during its transport. Surplus SO2 in the transporting plume reacted to abundant OH over the sea surface, formed H2SO4, and contributed to the consequently increased sulfate concentrations. The observed sulfate data in Korea confirm that sulfate concentrations over the sea surface areas enhanced sulfate concentrations in Korea (from 12.27 to 13.74㎍/m3). The sulfate, however, was not directly transported from upwind regions but chemically produced during the transport. The results of several sensitivity simulations with varied meteorology revealed that the changes in chemical sulfate production rates during the transport of sulfate were mainly affected by temperature.

SEDIMENT AND SUSPENDED PARTICULATE MATTER OF JAKARTA BAY, INDONESIA

Jakarta Bay is a semi enclosed bay located in the northern coast of Jakarta Metropolitan City. Hydrologically 13 rivers flowing in the Jakarta region and there are three big rivers with significant discharge to the Jakarta Bay namely Citarum, Ciliwung, and Cisadane Rivers. Jakarta, as Indonesian capital city with population of 8.725.630 inhabitants, and another 15 million people live in the surrounded suburban of Jakarta, creates a significant anthropogenic impact to the environmental system. Limited infrastructures, such as no sewerage system and lack of industrial waste management, cause the rivers in this region have over their carrying capacity.Seventeen sampling stations were determined in the Jakarta Bay, consisting of 5 stations at the river mouths (estuaries) and other 12 stations in the bay spreading from the coastal to offshore areas. Water and sediment samples were taken during 2 monsoonal or seasonal variations, August 2006 for dry season and February 2007 for rainy season respectively. Additionally, samples were also taken in May 2007.Sediment distribution in the estuary consists mostly of black clay. The sediments clays were bad smell. In the coastal region and in the dry season, the sediments consists of black clay and at one sampling site (station S3) the sediment was bad smell. However, all sampling sites became bad smell in the rainy season. In the inner bay area, sediments were greyish green sandy clay with some shell fragments. In the outer bay, the sediments were dominated by greyish green clayey sand with some shell fragments. The black clay with bad smell is indicative of anthropogenic influence from Jakarta River Basin. C/N ratio of the sediments in the dry season ranged from 1 to about 4.2 where in the estuaries (at stations M1, M2 and M4) the ratio were higher compared to the inner and outer bays. The C/N ratio of suspended particulate matter ranged from the lowest ratio of 0.7 to the highest ratio of 17.7 at the bottom layer and lesser ranged of 0.7 to 9.8 at surface layer. POC concentrations ranged between 50-650 µM and 50-900 µM, in February and May, respectively. High concentrations of POC exists along the coastline or estuaries then decreasing toward the sea. POC is distributed widely in February than that in May due to higher discharge from the rivers. The average TOC concentrations in February is lower than that in May, but the TOC load in February was much higher than that in May due to the big differences of river discharge and because the samples were taken a week after the big flood in Jakarta area (February 4th - 6th, 2007). Total organic carbon fluxes from the river to the bay in February and May 2007 were 107.6 T /day C and 42.7 T /day C, respectively. Key words : sediment, anthropogenic influence, C/N Ratio, POC, TOC, flux

Weather Condition Dominates Regional PM2.5 Pollutions in the Eastern Coastal Provinces of China during Winter

China has suffered from severe particulate matter (PM) pollution in recent years. Both pollution areas and levels are increasing gradually. The PM pollution episodes not only occur in the traditional developed areas like the Yangtze River Delta (YRD) and the Beijing-Tianjin-Hebei (BTH) region, but also frequently happen in the eastern coastal provinces (ECPs) of China. Based on hourly fine-PM (PM2.5) concentrations during December 2013 to February 2014 of 55 cities located in the ECPs, we investigated the spatial and temporal variabilities of PM2.5 concentration and the corresponding meteorological conditions during winter. The results generally showed that the winter mean concentrations over all ECPs exceeded China’s national standard of 75 µg m–3, and the most polluted areas with mean concentrations exceeding 150 µg m–3 were in the southwest of Hebei and the west of Shandong Province. The PM2.5 concentrations in February were lower than December in most areas, especially in the YRD, but they were higher over the north of Hebei Province. The spatial distributions and monthly variations were strongly related to weather conditions. Overall, severe PM pollution corresponded with stable weather conditions: small Sea Level Pressure gradient, lower Planetary Boundary Layer (PBL) height and weaker winds. Statistics showed that the changes of the mean PM2.5 concentration over the ECP region lagged behind the variations in the PBL height and wind speeds by about 12–18 h, and the variations in weather conditions could explain about 71% (R2) of the overall changes in PM2.5 concentrations, indicating that regional PM2.5 pollution was dominated by weather conditions in the ECPs. This study gives insight into the PM2.5 pollution in the ECPs of China during winter, which would be helpful to predict and control the PM2.5 pollution for this area in the future.

First evaluation of neustonic microplastics in Black Sea waters

The Black Sea has a high risk of plastic pollution given the high river discharge of several industrialized countries into this semi-enclosed sea. Here, for the first time, the occurrence and distribution of microplastics are reported for the Black Sea. Microplastics were assessed from zooplankton samples taken during two cruises along the south eastern coast of the Black Sea in the November of 2014 and February of 2015. In each cruise neuston samples were collected at 12 stations using a WP2 net with 200 μm mesh. Microplastics (0.2–5 mm) were found in 92% of the samples. The primary shapes were fibres (49.4%) followed by plastic films (30.6%) and fragments (20%), and no micro beads were found. Average microplastic concentration in November (1.2 ± 1.1 × 103 par. m−3) was higher than in February (0.6 ± 0.55 × 103 par. m−3). Reduced concentrations in February were possibly caused by increased mixing. The highest concentrations of microplastics were observed in offshore stations during November sampling. The heterogeneous spatial distribution (0.2 × 103–3.3 × 103 par. m−3 for all samples) and accumulation in some stations could be associated to transport and retention mechanisms linked with wind and the dynamics of the rim current, as well by different sources of plastic. There were no statistically significant differences in MP concentration between sampling stations and sampling periods (t-test, p < 0.05).The relatively high microplastic concentrations suggest that Black Sea is a hotspot for microplastic pollution and there is an urgency to understand their origins, transportation and effects on marine life.

Spatio-temporal patterns of C : N : P ratios in the northern Benguela upwelling system

Abstract. On a global scale the ratio of fixed nitrogen (N) and phosphate (P) is characterized by a deficit of N with regard to the classical Redfield ratio of N : P = 16 : 1 reflecting the impact of N loss occurring in the oceanic oxygen minimum zones. The northern Benguela upwelling system (NBUS) is known for losses of N and the accumulation of P in sub- and anoxic bottom waters and sediments of the Namibian shelf resulting in low N : P ratios in the water column. To study the impact of the N : P anomalies on the regional carbon cycle and their consequences for the export of nutrients from the NBUS into the oligotrophic subtropical gyre of the South Atlantic, we measured dissolved inorganic carbon (CT), total alkalinity (AT), oxygen (O2) and nutrient concentrations in February 2011. The results indicate increased P concentrations over the Namibian shelf due to P efflux from sediments resulting in a C : N : P : -O2 ratio of 106 : 16 : 1.6 : 138. N reduction further increase C : N and reduce N : P ratios in those regions where O2 concentrations in bottom waters are &lt; 20 μmol kg−1. However, off the shelf along the continental margin, the mean C : N : P : -O2 ratio is again close to the Redfield stoichiometry. Additional nutrient data measured during two cruises in 2008 and 2009 imply that the amount of excess P, which is created in the bottom waters on the shelf, and its export into the subtropical gyre after upwelling varies through time. The results further reveal an inter-annual variability of excess N within the South Atlantic Central Water (SACW) that flows from the north into the NBUS, with highest N values observed in 2008. It is postulated that the N excess in SACW occurred due to the impact of remineralized organic matter produced by N2 fixation and that the magnitude of excess P formation and its export is governed by inputs of excess N along with SACW flowing into the NBUS. Factors controlling N2 fixation north of the BUS need to be addressed in future studies to better understand the role of the NBUS as a P source and N sink in the coupled C : N : P cycles.

가로림만의 이화학적 수질의 시.공간적 특성

The physico-chemical characteristics including water temperature, salinity, dissolved oxygen(DO), chemical oxygen demand (COD), chlorophyll-a(Chl. a), suspended particulate matter(SPM) and dissolved inorganic nutrients were investigated in the Garolim Bay, Yellow Sea, Korea in 2010 carried out six times per year at 11 fixed stations by Korea Fisheries Research & Development Institute. The water temperature, salinity, COD, dissolved inorganic nutrients, Chl. a and SPM showed significant difference between surface and bottom water but the other parameters didn`t. There were not significant difference between stations. The water temperature showed typical change patterns of the temperate seawater. The annual average of salinity showed more than 31 so that there could not have occurred low saline water. The average of DO from June to August showed over than 3mg/L which showed higher than the below standard value of the hypoxic (oxygen-deficient) water. The average of Chl. a varied at surface, at bottom layer in June and at surface, at bottom layer at August. The dissolved inorganic nutrients showed high concentration in February and low concentration in August due to the limitation of the freshwater input in summer and phytoplankton used to the dissolved inorganic nutrients. The ratio of DIN/DIP showed 30.52 at surface and 37.89 at bottom layer in June which was higher than other month. The SPM was 44.15mg/L at bottom layer in February which was the highest value in this study due to the northwest monsoon. Because of the actively water change in the open sea without inflow of freshwater from land in Garolom Bay, there were not occurred low saline water and hypoxic water. thus, this Bay showed good water quality and required to be conserved continuously as important costal area for fisheries.

Spatial and temporal variability in nutrient concentrations in Liverpool Bay, a temperate latitude region of freshwater influence

This paper presents data for the temporal and spatial distribution of nutrients in Liverpool Bay between 2003 and 2009 and an analysis of inputs of nutrients from the major rivers. The spatial distribution of winter nutrient concentrations are controlled by the region of freshwater influence (ROFI) in Liverpool Bay through the mixing of riverine freshwater and Irish Sea water, with strong linear relationships between nutrient concentration and salinity between December and February. The location of highest spring and summer phytoplankton biomass reflects the nutrient distributions as controlled by the ROFI. Analysis of 7 years of data showed that the seasonal cycle of winter maximum nutrient concentrations in February and drawdown in April/May is a recurrent feature of this location, with the timing of the drawdown varying by several weeks between years. A comparison of observed nutrient concentrations in Liverpool Bay with those predicted from inputs from rivers has been presented. Nutrient concentrations in the rivers flowing into Liverpool Bay were highly variable and there was reasonable agreement between predicted freshwater nutrient concentrations using data from this study and riverine nutrient concentrations weighted on the basis of river flow, although the exact nature of mixing between the rivers could not be determined. Predicted Irish Sea nutrient concentrations in the winter were lower than those reported for the input waters of the North Atlantic, supporting findings from previous work that nitrogen is lost through denitrification in the Irish Sea.