High Concentrations Of NO Research Articles

Groundwater nitrogen and chloride following closure of an earthen manure storage in southern Alberta.

Earthen manure storage (EMS) facilities no longer in operation present a risk to the environment, and there is limited guidance to support the planning and implementation of EMS closures. A combined dairy and feedlot in southern Alberta, Canada, had an EMS in operation for about 55yr. The dairy portion ceased operation in 2015, and the EMS was emptied; however, no specific steps for permanent closure to minimize possible contamination were followed. The objective of this study was to document changes in shallow groundwater quality following an EMS closure. This EMS was already instrumented to assess its effect on the groundwater quality as part of a long-term study prior to closure. Eight groundwater monitoring wells were installed 2-38m from the EMS in up- and downgradient positions in 2010 and 2011. Groundwater samples were collected about three times annually prior to and for 4 yr after the EMS closure and were analyzed for NO3 -N, NH3 -N, and Cl- . Wells screened at more than 8m deep were not affected by the EMS prior to or after closure. However, in shallower wells, groundwater NO3 -N concentration increased to a maximum 3 yr after closure (in 2018) and then decreased afterward. In a shallow well 40m downgradient from the EMS, the NO3 -N concentrations decreased from 31mg L-1 in 2015 to 5mg L-1 in 2019, and the Cl- concentration decreased from 64 to 53mg L-1 , suggesting the contamination plume had dispersed. However, the EMS was still a source of contamination because high concentrations of NO3 -N (0.05-40mg L-1 ) and Cl- (43-862mg L-1 ) were present in wells adjacent to the EMS 4 yr after closure.

High gas sensor performance of WO3 nanofibers prepared by electrospinning

WO3 is a widely studied gas sensor material that commonly exhibits excellent sensitivity and selectivity toward NO2 detection. In this study, the influence of the heating rate on the thickness and grain size of WO3 nanofibers synthesized by electrospinning was evaluated. The materials were analyzed using XRD, Raman, and UV-Vis spectroscopies, as well as FEG-SEM, TG-DTA, and the BET method. Results showed that continuous nanofibers with particle size dependent on the heating rate were obtained at 500 °C. The gas sensing performance of WO3 nanofibers calcined at 10 °C/min (NF500–10) was investigated due to its higher surface area. NF500–10 device presented a high sensor signal for low and high NO2 concentrations at temperatures ranging from 150 °C to 300 °C. The sensor signals for 25 ppm of NO2 at 150 °C are substantially higher than those of several previous reports. Moreover, high selectivity against potential interferents (H2 and CO) was observed at all operating temperatures. A sensing mechanism based on the interaction between NO2 molecules and the surface of the WO3 nanofibers was proposed to explain the high sensor response. In conclusion, WO3 nanofibers were found to be an attractive sensing material to detect both low and high NO2 concentrations with excellent selectivity.

Influence of land use and change in the proportion of electron donors required for denitrification on N2O in groundwater.

Nitrate (NO3-) and nitrous oxide (N2O) accumulate in groundwater in relation to human activities and pose multiple threats to the global environment (harming human health and atmospheric damage). This study focused on the evaluation of groundwater NO3-, N2O, and its indirect emission factor under different land use types (agricultural land, urban land, and forest) and response mechanism of major anions to dissolved N2O within groundwater in Dexing which has the largest copper mine in Asia. Specifically, this work used self-organizing maps (SOMs) to identify which anion conditions (NO3-, SO42-, F-, Cl-) and water quality parameters were suitable for the accumulation of groundwater N2O. Finally, we found that the shallow groundwater of agricultural land has a high concentration of NO3- and N2O and the agricultural activity has a significant effect on the temporal and spatial variation of N2O in groundwater. The result of SOMs combined with the positive correlation between N2O and NO3-/SO42- suggested that the electron donor required for denitrification has a significant effect on N2O accumulation. In this respect, when an increased proportion of reduced sulfur is available as an electron donor for autotrophic denitrification, this results in lower concentrations of N2O in groundwater. Through the comprehensive evaluation of the anion conditions and N2O in groundwater under different land use types, this study case can help to estimate the N2O indirect emission from groundwater, so as to constrain the global nitrogen budget.

KUALITAS UDARA DAN POTENSI TRANSMISI COVID-19 DI PULAU JAWA

Penularan SARS-CoV-2 di Indonesia semakin mengkhawatirkan. Pandemik COVID-19 tidak hanya berdampak pada individu yang terinfeksi langsung, tetapi juga berimbas kepada para penyintas kolateral, yaitu mereka yang kehidupannya ikut terdisrupsi akibat krisis. Pulau Jawa adalah episentrum penularan COVID-19 di Indonesia. Beberapa studi menunjukkan bahwa kejadian COVID-19 memiliki hubungan yang erat dengan tingginya konsentrasi zat partikulat di udara. Penelitian ini bertujuan untuk mengetahui hubungan antara kualitas udara dan risiko penularan COVID-19 di Pulau Jawa. Kualitas udara diukur dengan konsentrasi NO2, sedangkan risiko penularan COVID-19 direfleksikan oleh Indeks Kewaspadaan COVID-19. Penelitian ini menggunakan empat model untuk melihat pengaruh kadar NO2 terhadap Indeks Kewaspadaan COVID-19, dimana variabel kepadatan penduduk ditambahkan sebagai kontrol. Model-0 adalah model dasar tanpa efek kelompok dan efek spasial. Model-1 adalah pengembangan dari Model-0 dengan menambahkan efek spasial. Model-2 adalah pengembangan dari Model-0 dengan menambahkan efek kelompok. Sedangkan, Model-3 adalah model lengkap dengan efek kelompok dan efek spasial. Hasil analisis menunjukkan bahwa Model-3 adalah model terbaik dalam menjelaskan pengaruh kadar NO2 terhadap Indeks Kewaspadaan COVID-19. Model-3 mampu meningkatkan kinerja model secara substansial. Hasil pengujian mengindikasikan bahwa kadar NO2 berpengaruh positif dan signifikan terhadap Indeks Kewaspadaan COVID-19, setelah efek kelompok dan efek spasial diperhitungkan. Dengan demikian, disimpulkan bahwa semakin tinggi konsentrasi NO2 yang mencerminkan semakin buruk kualitas udara, semakin tinggi pula risiko penularan COVID-19. Hasil ini memiliki implikasi penting untuk strategi pencegahan penyebaran COVID-19, khususnya pada daerah-daerah dengan tingkat pencemaran udara yang tinggi.

Assessing the antinociceptive effect of nitrous oxide to tetanic stimulation in anaesthetised patients with new intra-operative nociception monitors: An observational study.

Nitrous oxide (N2O) has been used since the 19th century for its analgesic, antinociceptive and anxiolytic effects during surgical procedures in awake and anaesthetised patients. However, quantification of noxious stimuli that occur under general anaesthesia is a constant challenge for anaesthesiologists, and recently two new indices have been developed to assess intra-operative nociception. The aim of this study was to quantify with new indices as well as with more classical clinical parameters the antinociceptive effect of N2O during general anaesthesia. Prospective, open label, patient-blinded, observational and descriptive trial. Single-centre academic hospital. Forty American Society of Anesthesiologists' physical status 1 to 3 patients undergoing general anaesthesia for elective abdominal surgery via laparotomy were recruited. Intra-operative pain was assessed using a standardised electrical stimulation of the forearm (tetanic stimulation at 70 mA, 100 Hz for 30 s), at 0, 25 and 50% inhaled N2O/O2. Heart rate (HR), mean arterial blood pressure, bispectral index, the analgesia nociception index and the nociception level (NOL) index were used to evaluate intra-operative nociception before and after each standardised tetanic stimulation. There was a 16% reduction of the analgesia nociception index reaction, a 31% reduction of the NOL reaction and a 51% reduction of the HR reaction to a standardised electrical tetanic nociceptive stimulation during administration of 50% N2O. Administration of 50 or 25% inhaled N2O produced the same quality of antinociception based on HR and NOL index analyses. HR and the NOL index were the best parameters to identify the antinociceptive effect of intra-operatively administered N2O. In anaesthetised patients, our study demonstrated clinically significant antinociceptive properties of N2O. Our results showed that low concentrations of N2O (25%) are as effective as higher concentrations (50%) to achieve a significant antinociceptive effect. These findings may help decrease negative effects of using higher concentrations of N2O, including its side effects and its environmental pollution. ClinicalTrials.gov registration identifier: NCT02701478.

Emission dispersion modeling and geospatial analysis of vehicular emissions in some parts of Benin City, Nigeria

Over the years, decline in air quality has been connected to the growing rate of urbanization and increasing number of vehicles on the roads. Most of the pollutants emitted from vehicular activities have been observed to have adverse effects on individuals as well as the atmosphere. Although, the focus of this study is to develop an emission dispersion model to predict the concentration of specific air pollutants with distance, the application of geostatistical technique such as Kriging interpolation to study the spatial distribution of pollutants from vehicular emissions around the study area was also exemplified. Seven (7) georeferenced points, namely, Ugbowo main gate, Ekosodin junction, Agen junction, Super D junction, Nitel junction, Okhunmwun junction and Oluku market junction were used for data collection. Pollutants from vehicular emissions, namely, nitrogen dioxide (NO2), carbon monoxide (CO) including the total radiation were monitored in the morning and evening for a period of 35 days (7th July to 12th August 2020) with the aid of portable toxic gas monitors and radiation alert meters. Other parameters of interest, which were also measured include maximum temperature and wind speed using infra-red thermometers and portable anemometer respectively. To ascertain the quality of the data, selected preliminary analysis, namely, test of normality, test of homogeneity, outlier detection and reliability test were done. Result of the study showed a high concentration of NO2, CO and total radiation around Ugbowo main gate and Okhunmwun community and environs especially during the peak hours of evening (5.0 p.m. – 6.0 p.m.) when the traffic load is high.

Spatiotemporal Variations of NO<sub>2</sub> over Fukuoka Japan, Observed by Multiple MAX-DOAS and 3-D Coherent Doppler Lidar

To clarify three-dimensional (3-D) spatiotemporal variations and horizontal–vertical transport processes in nitrogen dioxide (NO2) over urban areas, combined NO2 profile observations by multiple Multi AXis Differential Optical Absorption Spectroscopy (MAX-DOAS) and direct wind observations by 3-D coherent Doppler lidar were made over an urban area in Japan. MAX-DOAS measurements were conducted at Yakuin and Fukuoka University in Fukuoka urban area with high temporal resolution of four minutes.Enhanced NO2 concentrations were often observed over the city center. We conducted a case study on 29 November 2018 under clear sky conditions and NO2 profiles were well retrieved. Using MAX-DOAS at two locations, high NO2 concentrations were observed near the surface of the city center in the morning. Higher NO2 concentrations appearing gradually at higher altitudes over the city center and disappearing in the afternoon are explained using direct evidence of a 3-D wind field: an airmass with a high NO2 concentration was transported upward over the city center. Then, the airmass was advected landward by a sea breeze. Multiple MAX-DOAS combined with 3-D Doppler lidar constitutes a powerful tool for elucidating horizontal–vertical transport processes. It can contribute to the improvement of data retrieval by satellites for urban areas.

Species and potential sources of phosphorus in groundwater in and around Mataram City, Lombok Island, Indonesia

Geochemical evaluation of the species and potential sources of P in groundwater in and around Mataram City, Lombok Island, Indonesia can aid in the initial research on evaluating the fate of P when detailed geological information is unavailable. The results of ion chromatography and inductively coupled plasma-optical emission spectroscopy show that the concentrations of PO43– and total dissolved P (TDP) in groundwater range from approximately 0.1 to 8.5 mg l–1 and from 0.04 to 2.95 mg l–1, respectively. Dissolved inorganic P accounted for 86%, on average, of the TDP concentration, and PO43– represented the predominant P species in this groundwater. The potential sources for most of this dissolved PO43–, according to indices developed based on the PHREEQC software and groundwater quality data, could be the dissolution of hydroxyapatite and/or vivianite minerals. However, the potential sources of dissolved PO43– in groundwater with a TDP concentration of ≥ 1 mg l–1 is likely to be the reduction of Fe(III)–(hydro)oxides, the initial decomposition of organic matter, or the dissolution of carbonate-rich fluorapatite considering the Fe2+, dissolved organic carbon, Ca2+ and F− concentrations measured. In addition, as several groundwater samples had a TDP concentration of ≤ 1 mg l–1 and comparatively high concentration of NO3–, other potential sources of dissolved PO43– in this groundwater could be anthropogenic.

INTENSITY OF NITRIC OXIDE SYNTHESIS IN THE BLOOD OF RATS UNDER THE INFLUENCE OF SODIUM FLUORIDE

The influence of fluoride ion as a chemical agent affects the metabolism, the change of which is manifested in functional and structural changes. The final stable metabolites of NO include nitrite and nitrate anions (NO2, NO3), the concentration of which serves as an indirect method for estimating the intensity of NO synthesis. The concentration of NO is a major factor in its numerical biological effects (regulatory, protective). At low NO concentrations, direct effects aimed at maintaining homeostasis, such as the vascular, respiratory, and nervous systems, predominate; at high concentrations of NO, indirect effects prevail, due primarily to the formation of peroxynitrite. It is known that when the rate of free radical reactions in the body increases, NO can react with a superoxide anion radical to form peroxynitrite, a highly reactive compound with destructive properties against proteins and lipids. Oral administration of FN to rats in doses of 1/10 and 1/100 DL50 leads to an increase in the content of nitrite and nitrate anions in the blood plasma during the first 30 days, which indirectly indicates excess production of nitric oxide, which in the initial stages of intoxication may play a compensatory role, but subsequently cause pathological reactions associated with the activation of oxidative stress. The decrease in nitrite and nitrate anions at the end of long-term action of FN indirectly indicates a decrease in nitric oxide generation, which may be associated, in particular, with an increase in peroxynitrite concentration due to the use of nitric oxide in reaction with superoxide anion radical and antioxidant deficiency.

A intermediate concentration of atmospheric nitrogen dioxide enhances PSII activity and inhibits PSI activity in expanded leaves of tobacco seedlings

Nitrogen dioxide (NO2) is a major air pollutant that affects plant growth, development and yields. Previous studies have found that atmospheric NO2 changes plant photosynthesis in a concentration-dependent manner. Low concentrations of NO2 (4.0 μL L−1) can increase photosynthetic rates, while high concentrations of NO2 (16.0 μL L−1) can have an inhibitory effect. However, the specific effects of a critical intermediate concentration of NO2 on the photosynthetic apparatus of plants has remained unknown. Therefore, in this study, tobacco seedlings at three-leaf ages were fumigated with a intermediate concentration of 8.0 μL L−1 NO2 for 15 days to determine the effects on leaf weight, leaf number per plant, chlorophyll content, net photosynthetic rate, the reaction center activity of photosystems I and II (PSI and PSII, respectively) and core protein gene expression (PsbA and PsaA). Fumigation with 8.0 μL L−1 NO2 increased the number of leaves per plant and the weight of leaves, and the leaves became dark green and curly after 10 days of fumigation. During NO2 fumigation for 15 days, the chlorophyll content, PSII maximum photochemical efficiency (Fv/Fm), electron transfer rate (ETR) and non-photochemical quenching (NPQ) increased most in the oldest leaves (Lmax leaves), but decreased PSI activity (∆I/Io). The Fv/Fm, ETR and NPQ in the youngest leaves (Lmin leaves) were lower than those of Lmax leaves, but the actual photochemical efficiency (ΦPSII) of PSII increased most and ∆I/Io was the highest in these samples. The Fv/Fm, ETR, NPQ and ΦPSII in the leaves at the middle leaf age (Lmid leaves) were lower than those of Lmin and Lmax leaves, but the relative fluorescence intensity of point L (VL) and the relative fluorescence intensity of point K (VK) decreased the most in these samples. Thus, this critical concentration of atmospheric NO2 increased the activity of PSII and inhibited PSI activity in expanded leaves of tobacco seedlings.

Parametric study and mechanism analysis of NO removal by cobalt ethylenediamine

Nitrogen oxides (NOx) are one of the major air pollutants, causing many environmental problems, NO being the main component of NOx. In the present work, the solution of cobalt ethylenediamine was used to removal NO via the wet denitrification method. For industrial applications, this experiments was carried out in the packing tower and the influence of CO2 and SO2 on the removal rate of NO also was analyzed. It found that the concentration of [Co(en)3]2+, pH, gas flow rate, the liquid-gas ration, the concentration of NO and O2 strongly affected the denitrification efficiency at a different rate. More precisely, the concentration of 0.025 mol/L of [Co(en)3]2+, pH of 13.0, low gas flow rate, high liquid-gas ratio, and high concentration of NO and O2 was proved to be recommendable for the highest efficiency. Furthermore, a reduced amount of CO2 and SO2 in the flue gas would be a recommended method for NO removal. Although three different reaction paths have been proposed by previous studies, they are still controversial. To determine which is the most accurate, three different reaction paths were checked by experiments in this work. The results implied that the cobalt ethylenediamine was complexed with NO and O2 to produce [Co(en)2(NO)(OH−)]+ and [Co2(en)4O2(OH)]3+, and then these products reacted each other to regenerate the [Co(en)3]2+. As a summary, we can affirm that the present work can guide toward the industrialization of wet denitrification using cobalt ethylenediamine.

Impact of weather and emission changes on NO2 concentrations in China during 2014-2019.

Nitrogen dioxide (NO2) is one of the most important air pollutants that highly affect the formation of secondary fine particles and tropospheric ozone. In this study based on hourly NO2 observations from June 2014 to May 2019 and a regional air quality model (WRF-CMAQ), we comprehensively analyzed the spatiotemporal variations of NO2 concentrations throughout China and in 12 urban agglomerations (UAs) and quantitatively showed the anthropogenic and meteorological factors controlling the interannual variations (IAVs). The ground observations and tropospheric columns show that high NO2 concentrations are predominantly concentrated in UAs such as Beijing-Tianjin-Hebei (BTH), the Shandong Peninsula (SP), the Central Plain (CP), Central Shaanxi (CS), and the Yangtze River Delta (YRD). For different UAs, the NO2 IAVs are different. The NO2 increased first and then decreased in 2016 or 2017 in BTH, YRD, CS, and Cheng-Yu, and decreased from 2014 to 2019 in Harbin-Changchun, CP, SP, Northern Slope of Tianshan Mountain, and Beibu-Gulf, while increased slightly in the Pearl River Delta (PRD) and Hohhot-Baotou-Erdos-Yulin (HBEY). The NO2 IAVs were primarily dominated by emission changes. The net wintertime decreases of NO2 in BTH, Yangtze River Middle-Reach, and PRD were mostly contributed by emission reductions from 2014 to 2018, and the significant increase in the wintertime in HBEY was also dominated by emission changes (93%). Weather conditions also have an important effect on the NO2 IAVS. In BTH and HBEY, the increases of NO2 in winter of 2016 are mainly attributed to the unfavorable weather conditions and for the significant decreases in the winter of 2017, the favorable weather conditions also play a very important role. This study provides a basic understanding on the current situation of NO2 pollution and are helpful for policymakers as well as those interested in the study of tropospheric ozone changes in China and downwind areas.

Sources, Influencing Factors, and Pollution Process of Inorganic Nitrogen in Shallow Groundwater of a Typical Agricultural Area in Northeast China

As one of the largest agricultural areas, the Sanjiang Plain of Northeast China has faced serious inorganic nitrogen pollution of groundwater, but the sources and the formation mechanism of pollution in the regional shallow groundwater remain unclear, which constrains the progress of pollution control and agricultural development planning. An investigation on potential nitrogen sources, groundwater inorganic nitrogen compounds (NH4+, NO3−, NO2−), and topsoil total nitrogen concentration (TN) was conducted in a typical paddy irrigation area of Sanjiang Plain. Multivariate statistical analysis combined with geospatial-based assessment was applied to identify the sources, determine the governing influencing factors, and analyze the formation process of inorganic nitrogen compounds in shallow groundwater. The results show that the land use type, oxidation-reduction potential (Eh), groundwater depth, NO2− concentration, and electrical conductivity (EC) are highly correlated with the NO3− pollution in groundwater, while DO and Eh affected the distribution of NH4+ most; the high concentrations of NO3− in sampling wells are most likely to be found in the residential land and are distributed mainly in densely populated areas, whereas the NH4+ compounds are most likely to accumulate in the paddy field or the lands surrounded by paddy field and reach the highest level in the northwest of the area, where the fields were cultivated intensively with higher fertilization rates and highest values of topsoil TN. From the results, it can be concluded that that the NO3− compounds in groundwater originated from manure and domestic waste and accumulated in the oxidizing environment, while the NH4+ compounds were derived from N fertilization and remained steady in the reducing environment. NO2− compounds in groundwater were the immediate products of nitrification as a result of microorganism activities.

Effect of grazing exclusion on nitrous oxide emissions during freeze-thaw cycles in a typical steppe of Inner Mongolia

Grazing exclusion of grasslands has traditionally been considered to reduce nitrogen inputs and decrease nitrous oxide (N2O) emissions. However, recent studies have shown that grazing exclusion may increase N2O emissions because of freeze-thaw cycles. In this study, year-round N2O fluxes (including high-frequency measurements during the freeze-thaw cycles) were measured in three sites that included long-term grazing exclusion (ungrazed since 1979, UG79), short-term grazing exclusion (ungrazed since 1999, UG99), and continuously grazed (CG), in Inner Mongolia grassland. The results showed that: 1) across the entire period of observations, mean annual N2O fluxes were the highest at UG99 (12.2 μg m−2 h-1), followed by CG (8.6 μg m−2 h-1) and UG79 (7.5 μg m−2 h-1); 2) during spring freeze-thaw cycles, cumulative N2O emissions were significantly higher at UG99 than UG79 and CG (P < 0.05); 3) freeze-thaw cycles had significant effects on N2O emissions with strong pulse emissions exhibited at the beginning of the spring thaw period; and 4) structural equation model analysis indicated that soil water content was a predominant environmental factor that caused increased N2O emissions, while other factors tended to affect N2O emissions indirectly. The results confirmed that short-term grazing exclusion could increase N2O emissions owing to the high N2O concentration during freeze-thaw cycles, associated with high quantities of snowmelt water. However, the effects of long-term grazing exclusion on N2O emissions showed no differences compared with grazing management. This suggests that grazing exclusion does not always result in an increase in N2O emissions during freeze-thaw cycles as it is more controlled by soil liquid water content. Thus the new finding of the event emissions of N2O should come up with more reliable estimates of soil‐atmosphere trace fluxes.

Long-Term Exposure to Air Pollutants and Cognitive Function in Taiwanese Community-Dwelling Older Adults: AFour-Year Cohort Study.

Previous studies have assessed limited cognitive domains with relatively short exposure to air pollutants, and studies in Asia are limited. This study aims to explore the association between long-term exposure to air pollutants and cognition in community-dwelling older adults. This four-year prospective cohort study recruited 605 older adults at baseline (2011-2013) and 360 participants remained at four-year follow-up. Global and domain-specific cognition were assessed biennially. Data on PM2.5 (particulate matter≤2.5μm diameter, 2005-2015), PM10 (1993-2015), and nitrogen dioxide (NO2, 1993-2015) were obtained from Taiwan Environmental Protection Administration (TEPA). Bayesian Maximum Entropy was utilized to estimate the spatiotemporal distribution of levels of these pollutants. Exposure to high-level PM2.5 (>29.98μg/m3) was associated with an increased risk of global cognitive impairment (adjusted odds ratio = 4.56; β= -0.60). High-level PMcoarse exposure (>26.50μg/m3) was associated with poor verbal fluency (β= -0.19). High-level PM10 exposure (>51.20μg/m3) was associated with poor executive function (β= -0.24). Medium-level NO2 exposure (>28.62 ppb) was associated with better verbal fluency (β= 0.12). Co-exposure to high concentrations of PM2.5, PMcoarse or PM10 and high concentration of NO2 were associated with poor verbal fluency (PM2.5 and NO2: β= -0.17; PMcoarse and NO2: β= -0.23; PM10 and NO2: β= -0.21) and poor executive function (PM10 and NO2: β= -0.16). These associations became more evident in women, apolipoprotein ɛ4 non-carriers, and those with education > 12 years. Long-term exposure to PM2.5 (higher than TEPA guidelines), PM10 (lower than TEPA guidelines) or co-exposure to PMx and NO2 were associated with poor global, verbal fluency, and executive function over 4 years.

Characterization of the hydrochemistry of water resources of the Weibei Plain, Northern China, as well as an assessment of the risk of high groundwater nitrate levels to human health.

This study aimed to evaluate the hydrochemistry of the water resources of the Weibei Plain, Northern China, as well as the risks posed by high groundwater nitrate concentrations to human health. Groundwater and surface water samples numbering 168 and 14, respectively, were collected during the dry and wet seasons. Water in the study area was weakly alkaline, falling into a hard-fresh or hard-brackish category. The groundwater chemical types were mainly SO4·Cl-Ca·Mg (59.5%) and HCO3-Ca·Mg (28.6%), whereas the dominant chemistry type of surface water was SO4·Cl-Na (78.6%). Groundwater showed relatively high concentrations of NO3-, with average dry and wet season concentrations of 212mg·L-1 and 223mg·L-1, respectively, whereas surface water had a low NO3- content. The major processes affecting water chemistry were determined to be rock weathering, such as silicate weathering and evaporative dissolution, as well as cation exchange. NO3- in groundwater was found to mainly originate from anthropogenic inputs such as agricultural production and domestic sewage. The entropy-weight water quality index (EWQI) assessment showed that although the quality of surface water was generally good, more than half of the groundwater samples failed drinking water standards, with NO3- identified as being the most problematic parameter affecting the water quality evaluation. Risk assessment of high groundwater nitrate concentrations indicated that long-term domestic use of groundwater in the study area can put the health of residents at great risk. Totals of 81% and 75% of the groundwater samples exceeded the acceptable limit for non-carcinogenic risk (HI=1) to infants during the dry and wet seasons, respectively, whereas 75% and 71.3% of samples exceeded the acceptable limit for children, respectively. Future management of water in the Weibei Plain should prioritize the control groundwater nitrate pollution.

A novel injection technique: using a field-based quantum cascade laser for the analysis of gas samples derived from static chambers

Abstract. The development of fast-response analysers for the measurement of nitrous oxide (N2O) has resulted in exciting opportunities for new experimental techniques beyond commonly used static chambers and gas chromatography (GC) analysis. For example, quantum cascade laser (QCL) absorption spectrometers are now being used with eddy covariance (EC) or automated chambers. However, using a field-based QCL EC system to also quantify N2O concentrations in gas samples taken from static chambers has not yet been explored. Gas samples from static chambers are often analysed by GC, a method that requires labour and time-consuming procedures off-site. Here, we developed a novel field-based injection technique that allowed the use of a single QCL for (1) micrometeorological EC and (2) immediate manual injection of headspace samples taken from static chambers. To test this approach across a range of low to high N2O concentrations and fluxes, we applied ammonium nitrate (AN) at 0, 300, 600 and 900 kg N ha−1 (AN0, AN300, AN600, AN900) to plots on a pasture soil. After analysis, calculated N2O fluxes from QCL (FN2O_QCL) were compared with fluxes determined by a standard method, i.e. laboratory-based GC (FN2O_GC). Subsequently, the comparability of QCL and GC data was tested using orthogonal regression, Bland–Altman and bioequivalence statistics. For AN-treated plots, mean cumulative N2O emissions across the 7 d campaign were 0.97 (AN300), 1.26 (AN600) and 2.00 kg N2O-N ha−1 (AN900) for FN2O_QCL and 0.99 (AN300), 1.31 (AN600) and 2.03 kg N2O-N ha−1 (AN900) for FN2O_GC. These FN2O_QCL and FN2O_GC were highly correlated (r=0.996, n=81) based on orthogonal regression, in agreement following the Bland–Altman approach (i.e. within ±1.96 standard deviation of the mean difference) and shown to be for all intents and purposes the same (i.e. equivalent). The FN2O_QCL and FN2O_GC derived under near-zero flux conditions (AN0) were weakly correlated (r=0.306, n=27) and not found to agree or to be equivalent. This was likely caused by the calculation of small, but apparent positive and negative, FN2O when in fact the actual flux was below the detection limit of static chambers. Our study demonstrated (1) that the capability of using one QCL to measure N2O at different scales, including manual injections, offers great potential to advance field measurements of N2O (and other greenhouse gases) in the future and (2) that suitable statistics have to be adopted when formally assessing the agreement and difference (not only the correlation) between two methods of measurement.

Global-Scale Patterns and Trends in Tropospheric NO2 Concentrations, 2005–2018

Nitrogen dioxide (NO2) is an important air pollutant with both environmental and epidemiological effects. The main aim of this study is to analyze spatial patterns and temporal trends in tropospheric NO2 concentrations globally using data from the satellite-based Ozone Monitoring Instrument (OMI). Additional aims are to compare the satellite data with ground-based observations, and to find the timing and magnitude of greatest breakpoints in tropospheric NO2 concentrations for the time period 2005–2018. The OMI NO2 concentrations showed strong relationships with the ground-based observations, and inter-annual patterns were especially well reproduced. Eastern USA, Western Europe, India, China and Japan were identified as hotspot areas with high concentrations of NO2. The global average trend indicated slightly increasing NO2 concentrations (0.004 × 1015 molecules cm−2 y−1) in 2005–2018. The contribution of different regions to this global trend showed substantial regional differences. Negative trends were observed for most of Eastern USA, Western Europe, Japan and for parts of China, whereas strong, positive trends were seen in India, parts of China and in the Middle East. The years 2005 and 2007 had the highest occurrence of negative breakpoints, but the trends thereafter in general reversed, and the highest tropospheric NO2 concentrations were observed for the years 2017–2018. This indicates that the anthropogenic contribution to air pollution is still a major issue and that further actions are necessary to reduce this contribution, having a substantial impact on human and environmental health.

Evaluation of shallow groundwater for drinking purpose based on water quality index and synthetic pollution index in Changchun New District, China

Due to the impact of human agricultural production and climate and environmental changes, the applicability of groundwater for drinking purposes has attracted widespread attention. In order to quantify the hydrochemical characteristics of groundwater in Changchun New District and evaluate its quality for drinking purposes, 53 shallow groundwater samples were collected and analyzed. The results show that groundwater in aquifers in the study area is weakly alkaline. The abundance is in the order Ca2+ > Na+ > Mg2+ for cations, and HCO3− > Cl− > SO42− for anions. Ca-HCO3•Cl water type dominated the area, constituting about 26.41% of the total samples; Ca-HCO3 water type constituted about 22.64%; Ca•Na-HCO3 and Ca•Na-HCO3•Cl water types constituted 15.09% each, whereas Ca•Na-HCO3•Cl•SO4, Ca-HCO3•Cl•SO4, and Ca-SO4•Cl types made up 22.64% each. Correlation analysis (CA) and principal component analyses (PCA) show that rock weathering and dissolution, and human activities are the main reasons affecting the chemical composition of water in Changchun. The high concentrations of Pb, NO2−, Fe, and Mn must be widely concerned and may become the main environmental geological problems in the area. The analysis of water samples based on the water quality index model revealed that about 5.66%, 56.60%, 15.09%, 18.86%, and 3.77% of the shallow groundwater samples were excellent, good, poor, very poor, and unsuitable for drinking purposes, respectively. The analysis of groundwater samples based on the synthetic pollution index model showed that more than 37.74% of the groundwater samples were moderately polluted. The spatial distribution maps of the water quality index and the synthetic pollution index show that most of the shallow groundwater resources in the study area are clean and suitable for drinking, despite the risks of the shallow groundwater in the southeast of the study area.

The relationship between zooplankton community and environmental factors of Ghrib Dam in Algeria.

The effect of environmental factors on zooplankton diversity, abundance, and distribution in the Ghrib Dam water body was investigated for 2years from June 2013 to May 2015. A total of 61 species of zooplankton were recorded, including 45 rotifers, 13 cladocerans, and 3 copepods. The zooplankton abundance fluctuated between 4 and 3363ind.L-1, and its Shannon-Wiener index of zooplankton diversity in Ghrib Dam varied from H' = 1.15 to 3.77 during the 2-year study period. The highest diversity index was recorded at sampling site S1 in January 2015, due to the increase of specific richness (Ni = 27, Dmg = 5.75). Canonical correspondence analysis (CCA) was used to determine the influence of environmental factors in structuring the zooplankton species for each group. The results of CCA revealed that the most significant environmental factors influencing zooplankton community were water temperature (WT), dissolved oxygen (DO), phosphorus (PO4-), and NO3- (p < 0.05, Monte Carlo permutation test). Meanwhile, the appearance of Hexarthra sp., Collotheca pelagica, and Diaphanosoma brachyurum indicated a rise in WT. The existence of Filinia longiseta, Keratella quadrata, and Cyclops strenuus correlated with a rising of DO. Brachionus urceolaris, Filinia passa, Keratella tecta, Notholca acuminata, and Polyarthra dolichoptera positively coexisted in an increased PO4-. Daphnia longispina and Oxyurella tenuicaudis were positively associated with high concentration of NO3-.