Wet atmospheric deposition of nitrogen: 20 years measurement in Shenzhen City, China

We presented measurements of wet deposition of NH ₄ ⁺ –N and NO ₃ ^? –N from 1986 to 2006 in Shenzhen City, China. Over the past 20 years, NO ₃ ^? –N concentration had significantly increased, but a reverse trend was found for NH ₄ ⁺ –N. The main form of total inorganic nitrogen (TIN) was NH ₄ ⁺ –N and the average NH ₄ ⁺ –N/NO ₃ ^? –N ratio was 1.57 in this area. The contribution of NO ₃ ^? –N to TIN increased from 28–42% in the period of 1986–2000 to 50–63% during 2001–2006. The increased deposition flux of NO ₃ ^? –N resulted in the increasing trend of TIN, although NH ₄ ⁺ –N showed a decreasing trend over time. Average deposition flux of TIN during 1986–2006 was 13.24 kg/ha/year, with a minimum value of 6.03kg/ha/year in 1988 and a maximum value of 20.52 kg/ha/year in 1997. Wet deposition fluxes of N appeared to vary with season, 81% occurred in the warm season (from April to September). The wet deposition of TIN to the Shenzhen Reservoir reached 8,902 kg in 2006, which contributed 9.95% of the total nonpoint pollution to the reservoir and will be increased in the future.     

Soil response to a 3-year increase in temperature and nitrogen deposition measured in a mature boreal forest using ion-exchange membranes

The projected increase in atmospheric N deposition and air/soil temperature will likely affect soil nutrient dynamics in boreal ecosystems. The potential effects of these changes on soil ion fluxes were studied in a mature balsam fir stand (Abies balsamea [L.] Mill) in Quebec, Canada that was subjected to 3 years of experimentally increased soil temperature (+4 °C) and increased inorganic N concentration in artificial precipitation (three times the current N concentrations using NH₄NO₃). Soil element fluxes (NO₃, NH₄, PO₄, K, Ca, Mg, SO₄, Al, and Fe) in the organic and upper mineral horizons were monitored using buried ion-exchange membranes (PRS? probes). While N additions did not affect soil element fluxes, 3 years of soil warming increased the cumulative fluxes of K, Mg, and SO₄ in the forest floor by 43, 44, and 79 %, respectively, and Mg, SO₄, and Al in the mineral horizon by 29, 66, and 23 %, respectively. We attribute these changes to increased rates of soil organic matter decomposition. Significant interactions of the heating treatment with time were observed for most elements although no clear seasonal patterns emerged. The increase in soil K and Mg in heated plots resulted in a significant but small K increase in balsam fir foliage while no change was observed for Mg. A 6–15 % decrease in foliar Ca content with soil warming could be related to the increase in soil-available Al in heated plots, as Al can interfere with the root uptake of Ca.     

Observational and modeling study of dry deposition on surrogate surfaces in a South China city: implication of removal of atmospheric crustal particles

Dry deposition samples collected during 1999–2001 at a South China site using surrogate surfaces were analyzed by capillary electrophoresis. Collector surface properties played important roles to the dry deposition. The deposition velocities for various species ranged from 0.02 to 1.69 cm s^???1, in general agreement with literature values. More than 90% of Ca^2?+? was deposited by sedimentation and its comparable values of dry or wet removal residence times imply that dry deposition is an important atmospheric removal process for the ubiquitous crustal species in South China, compared with precipitation scavenging. Relatively good agreement was found when the species deposition velocities were modeled based on up-to-date knowledge of particle dry deposition. The total depositions for anthropogenic and crustal species in northern China are likely to be much higher than those in the south, including our site where the fluxes of the acidic species SO₄ ^2??? and NO₃ ^??? were 4.4 and 2.2 g m^???2 year^???1, respectively. The sum of dry deposition for cations Na^?+?, Ca^2?+?, Mg^2?+?, and K^?+? contributes 44% of the total flux, which is equivalent to the value estimated in Europe.     

Temporal variability in nutrient concentrations and loads in the River Tamar and its catchment (SW England) between 1974 and 2004

This study reports the results from the analyses of a 30-year (1974–2004) river water quality monitoring dataset for NO _x –N (NO₃–N?+?NO₂–N), NH₄–N, PO₄–P and SiO₂–Si at the tidal limit of the River Tamar (SW England), an agriculturally dominated and sparsely populated catchment. Annual mean concentrations of NH₄–N, PO₄–P and SiO₂–Si were similar to other rural UK rivers, while annual mean concentrations of NO _x –N were clearly lower. Estimated values for the 1940s were much lower than for those of post-1974, at least for NO₃–N and PO₄–P. Flow-weighted mean concentrations of PO₄–P decreased by approximately 60 % between 1974 and 2004, although this change cannot be unequivocally ascribed to either PO₄–P stripping from sewage treatment work effluents or reductions in phosphate fertiliser applications. Lower-resolution sampling (to once per month) in the late 1990s may also have led to the apparent decline; a similar trend was also seen for NH₄–N. There were no temporal trends in the mean concentrations of NO _x –N, emphasising the continuing difficulty in controlling diffuse pollution from agriculture. Concentrations of SiO₂–Si and NO _x –N were significantly and positively correlated with river flows ≤15 m³?s^?1, showing that diffuse inputs from the catchment were important, particularly during the wet winter periods. In contrast, concentrations of PO₄–P and NH₄–N did not correlate across any flow window, despite the apparent importance of diffuse inputs for these constituents. This observation, coupled with the absence of a seasonal (monthly) cycle for these nutrients, indicates that, for PO₄–P and NH₄–N, there were no dominant sources and/or both undergo extensive within-catchment processing. Analyses of nutrient fluxes reveal net losses for NO₃–N and SiO₂–Si during the non-winter months; for NO₃–N, this may be due to denitrification. Areal fluxes of NO _x –N from the catchment were towards the higher end of the range for the UK, while NH₄–N and PO₄–P were closer to the lower end of the ranges for these nutrients. These data, taken together with information on sestonic chlorophyll a, suggest that water quality in the lower River Tamar is satisfactory with respect to nutrients. Analyses of these monitoring data, which were collected at considerable logistical and monetary cost, have revealed unique insights into the environmental behaviour of key nutrients within the Tamar catchment over a 30-year period.     

Study on concentration of ambient NH 3 and interactions with some other ambient trace gases

We present diurnal variation of ambient ammonia (NH₃) in relation with other trace gases (O₃, CO, NO, NO₂, and SO₂) and meteorological parameters at an urban site of Delhi during winter period. For the first time, ambient ammonia (NH₃) was monitored very precisely and continuously using ammonia analyzer, which operates on chemiluminescence method. NH₃ estimation efficiency of the chemiluminescence method (>90%) is much higher than the conventional chemical trapping method (reproducibility 4.5%). Ambient NH₃ concentration reaches its maxima (46.17 ppb) at night and minimum during midday. Result reveals that the ambient ammonia (NH₃) concentration is positively correlated with ambient NO (r ²?=?0.79) and NO₂ (r ²?=?0.91) mixing ratio and negatively correlated with ambient temperature (r ²?=???0.32). Wind direction and wind speed indicates that the nearby (~500 m NW) agricultural fields may be major source of ambient NH₃ at the observational site.     

Impact of eutrophication on the occurrence of Trichodesmium in the Cochin backwaters, the largest estuary along the west coast of India

Phytoplankton studies in early 1970s have shown the annual dominance of diatoms and a seasonal abundance of Trichodesmium in the lower reaches of the Cochin backwaters (CBW) and adjacent coastal Arabian Sea during the pre-summer monsoon period (February to May). Surprisingly, more recent literature shows a complete absence of Trichodesmium in the CBW after 1975 even though their seasonal occurrence in the adjacent coastal Arabian Sea continued without much change. In order to understand this important ecological feature, we analyzed the long-term water quality data (1965–2005) from the lower reaches of the CBW. The analyses have shown that salinity did not undergo any major change in the lower reaches over the years and values remained >30 throughout the period. In contrast, a tremendous increase was well marked in levels of nitrate (NO₃) and phosphate (PO₄) in the CBW after 1975 (av. 15 and 3.5 μM, respectively) compared with the period before (av. 2 and 0.9 μM, respectively). Monthly time series data collected in 2004–2005 period from the lower reaches of the CBW and coastal Arabian Sea have clearly shown that the physical characteristics like salinity, temperature, water column stability, and transparency in both regions are very similar during the pre-summer monsoon period. In contrast, the nutrient level in the CBW is several folds higher (NO₃, 8_; PO₄, 4; SiO₄, 10; and NH₄, 19 μM) than the adjacent coastal Arabian Sea (NO₃, 0.7; PO₄, 0.5; SiO₄, 0.9; and NH₄, 0.6 μM). The historic and fresh time series data evidences a close coupling between enriched levels of nutrients and the absence of Trichodesmium in the Cochin backwaters     

Aerosol characteristics of different types of episode

Daily and hourly average data from nine air-quality monitoring stations distributed across central Taiwan, which include ten items (i.e., PM₁₀, PM_2.5, wind direction, wind speed, temperature, relative humidity, SO₂, NO₂, NO, and CO), were collected from 2005 to 2009. Four episode types: long-range transport with dust storms (DS), long-range transport with frontal pollution (FP), river dust (RD), and stagnant weather (SW), and one mixed type of episode were identified. Of these four episode types, the SW was the dominant type, averaging about 70 %. The mean ratio of PM_2.5/PM₁₀ was the lowest during the RD episodes (0.42), while the mean ratio of PM_2.5/PM₁₀ was the highest during the SW episodes (0.64). Fine aerosol (PM_2.5) and coarse aerosol (PM_10–2.5) samples were collected by high-volume samplers for chemical composition analysis, from only three stations (Douliou, Lunbei, and Siansi) during the days of SW, RD, DS, and FP. The concentrations of PM_2.5 and three ionic species (NH₄ ⁺, NO₃ ^?, and SO₄ ^2?) all showed significant differences among the four episode types. The highest levels of NO₃ ^? (12.1 μg/m³) and SO₄ ^2? (20.5 μg/m³) were found during the SW and FP episodes, respectively. A comparison on the spatial similarity of aerosol compositions among the episodes and/or non-episodes (control) was characterized by the coefficient of divergence (CD). The results showed higher CD values in PM_10–2.5 than in PM_2.5, and the CD values between RD episodes and the other three episodes were higher than those between two types of episode for the other three episodes. The ratios of SOR (sulfur oxidation ratio), SO₄ ^2?/EC (elemental carbon), NOR (nitrogen oxidation ratio), and NO₃ ^?/EC showed that sulfate formation was most rapid during the FP, while nitrate formation was most rapid during the SW.     

Seasonal variations of water column nutrients in the inner area of Ariake Bay, Japan: the role of muddy sediments

To investigate seasonal variations of nutrient distribution in the mudflat–shallow water system, we conducted field surveys once a month from August 2007 to July 2008 in the inner area of Ariake Bay (IAB), Japan. The NH₄ ⁺–N concentration of the water column increased in autumn because of the high NH₄ ⁺ release from the sediments, ranging from 850 to 3,001 μmol?m^?2?day^?1. The NO₃ ^?–N concentration was maximal in January, which was thought to be caused by NO₃ ^? release from the oxic sediments and by NO₃ ^? regeneration due to water column nitrification. The PO₄ ^3?–P concentration of the water column was high in summer–autumn due to the high PO₄ ^3? release from the reduced sediments, ranging from 22 to 164 μmol?m^?2?day^?1. We estimated the total amounts of DIN and PO₄ ^3?–P release (R _DIN and $ {R_{{\mathrm{P}{{\mathrm{O}}_4}}}} $ , respectively) from the muddy sediment area of the IAB. In summer–autumn, R _DIN and $ {R_{{\mathrm{P}{{\mathrm{O}}_4}}}} $ corresponded to about 47.7 % of DIN input and about 116.6 % of PO₄ ^3?–P input from the river, respectively. Thus, we concluded that the muddy sediments were an important source of nutrients for the water column of the IAB during summer–autumn. In addition, we found that phosphorus necessary for the growth of Porphyra (Porphyra yezoensis, Rhodophyceae) would be insufficient in the water column when phosphorus during the Porphyra aquaculture period is supplied only from the river. Therefore, the phosphorus release from the muddy sediments was thought to play an important role in the sustainable production of Porphyra in Ariake Bay.     

Temporal variability in water quality parameters—a case study of drinking water reservoir in Florida, USA

Our objective was to evaluate changes in water quality parameters during 1983–2007 in a subtropical drinking water reservoir (area: 7 km²) located in Lake Manatee Watershed (area: 338 km²) in Florida, USA. Most water quality parameters (color, turbidity, Secchi depth, pH, EC, dissolved oxygen, total alkalinity, cations, anions, and lead) were below the Florida potable water standards. Concentrations of copper exceeded the potable water standard of <30 μg?l^?1 in about half of the samples. About 75 % of total N in lake was organic N (0.93 mg?l^?1) with the remainder (25 %) as inorganic N (NH₃-N: 0.19, NO₃-N: 0.17 mg?l^?1), while 86 % of total P was orthophosphate. Mean total N/P was <6:1 indicating N limitation in the lake. Mean monthly concentration of chlorophyll-a was much lower than the EPA water quality threshold of 20 μg?l^?1. Concentrations of total N showed significant increase from 1983 to 1994 and a decrease from 1997 to 2007. Total P showed significant increase during 1983–2007. Mean concentrations of total N (n?=?215; 1.24 mg?l^?1) were lower, and total P (n?=?286; 0.26 mg?l^?1) was much higher than the EPA numeric criteria of 1.27 mg total N l^?1 and 0.05 mg total P l^?1 for Florida’s colored lakes, respectively. Seasonal trends were observed for many water quality parameters where concentrations were typically elevated during wet months (June–September). Results suggest that reducing transport of organic N may be one potential option to protect water quality in this drinking water reservoir.     

Influences of urban wastewaters on the stream water quality: a case study from Gumushane Province, Turkey

Urban wastewater in Turkey is primarily discharged without treatment to marine environments, streams and rivers, and natural and artificial lakes. Since it has been well established that untreated effluent in multi-use waters can have acute and chronic impacts to both the environment and human health, it is important to evaluate the consequences of organic enrichment relative to the structure and function of aquatic environment. We investigated the impacts of untreated municipal wastewater discharge from the city of Gumushane in the Eastern Black Sea Region of Turkey on the surface water quality of the stream Harsit. Several key water-quality indicators were measured: chemical oxygen demand (COD), ammonium nitrogen (NH ₄ ⁺ –N), nitrite nitrogen (NO ₂ ^? –N), nitrate nitrogen (NO ₃ ^? –N), total Kjeldahl nitrogen (TKN), total nitrogen (TN), orthophosphate phosphorus (PO ₄ ^3? –P), methylene blue active substances (MBAS), water temperature (t), pH, dissolved oxygen (DO), and electrical conductivity (EC). The monitoring and sampling studies were conducted every 15 days from March 2009 to February 2010 at three longitudinally distributed stations. While t, pH, DO, and EC demonstrated relatively little variability over the course of the study, other parameters showed substantial temporal and spatial variations. The most dramatic differences were noted in COD, NH ₄ ⁺ –N, NO ₂ ^? –N, TKN, TN, PO ₄ ^3— P, and MBAS immediately downstream of the wastewater discharge. Concentration increases of 309 and 418 % for COD, 5,635 and 2,162 % for NH ₄ ⁺ –N, 2,225 and 674 % for NO ₂ ^? –N, 283 and 478 % for TKN, 208 and 213 % for PO ₄ ^3? –P, and 535 and 1,260 % for MBAS were observed in the summer and autumn, respectively. These changes were associated with greatly diminished seasonal stream flows. Based on NO ₂ ^? –N, TKN, PO ₄ ^3— P, and MBAS concentrations, it was concluded that Harsit stream water was correctly classified as polluted. The most telling parameter, however, was NH ₄ ⁺ –N, which indicated highly polluted waters in both the summer and autumn. The elevated concentrations of both P and N in the downstream segment of the stream triggered aggressive growth of submerged algae. This eutrophication of river systems is highly representative of many urban corridors and is symptomatic of ongoing organic enrichment that must be addressed through improved water treatment facilities.     

北京夏季大气主要含氮无机化合物的变化规律与相互作用

利用SJAC-MOBIC/FIA在2006年8月16日—9月9日在线测量了北京城市大气细颗粒物中主要水溶性含氮离子组分(NO₃^-和 NH₄⁺),与重要含氮气态污染物(HNO₃、HNO₂和 NH₃),以追踪细颗粒物中含氮二次无机组分和含氮气态污染物的变化规律及其相互作用。观测期间,NO₃^- 和 NH₄⁺的平均浓度分别为13.08和11.93 μg/m³,它们与SO₄^2-浓度之和在细颗粒物(PM_2.5)中的平均比例为55%,明显高于其他季节;污染过程中,积聚模态颗粒物体积浓度及其与爱根核模态颗粒物体积浓度比值逐渐增加,说明二次转化是北京夏季细颗粒物的重要来源。白天HONO迅速光解产生OH自由基,而OH自由基是生成HNO₃的重要物种,因此HONO和HNO₃具有相反的日变化规律。在温度较高的白天,大气环境不利于NH₄NO₃的生成与存在;夜间低温高湿的条件下硝酸铵理论平衡系数Ke与气态氨和硝酸的乘积Km相当或低于后者,较有利于NH₄NO₃的生成。北京夏季大气具有足量气态NH₃以中和硫酸盐;但在NO₃^-与阳离子的电荷平衡中,金属阳离子也非常重要。     

北京市典型重污染过程中PM2.5载带水溶性无机离子污染特征分析

为研究北京地区冬季PM_(2.5)载带的水溶性无机离子组分污染特征,2013年1月在中国环境科学研究院内采用在线离子色谱(URG-9000B,AIM-IC)对PM_(2.5)中水溶性无机离子(SO_4~(2-)、NO_3~-、Cl~-、NH_4~+、Na~+、K~+、Mg~(2+)、Ca~(2+))进行监测与分析。结果表明,采样期间总水溶性无机离子(TWSI)浓度为61.0μg/m~3,其中二次无机离子SO_4~(2-)、NO_3~-、NH_4~+(SNA)占比达72.3%,在PM_(2.5)中占比为40.29%,表明北京市PM_(2.5)二次污染严重。重污染天[NO_3~-]/[SO_4~(2-)]表明,固定源污染较移动源更为显著。三元相图表明,在空气质量为优的情况下,NH_4~+(在SNA中占比为30.3%~65.5%,下同)主要以NH_4NO_3的形式存在,较少比例以(NH_4)_2SO_4存在;严重污染时,NH_4~+(47.3%~77.9%)主要以(NH_4)_2SO_4形式存在,其次以NH_4NO_3的形式存在,其余的NH_4~+以NH_4Cl的形式存在。[NO_3~-]/[SO_4~(2-)]日变化表明,早、晚机动车高峰影响北京重污染发生。     

Dynamics of atmospheric polychlorinated biphenyls (PCBs): concentrations, patterns, partitioning, and dry deposition level estimations in a residential site of Turkey

Air samples were collected at a residential site (Gulbahce, Bursa, Turkey) between August 2004 and April 2005 using a modified high volume air sampler. The mean of gas and particle phase concentrations of polychlorinated biphenyls (PCBs) were 468 ± 297 and 43 ± 37 pg m^???3 (average ± standard deviation, SD), respectively. The dominated PCB homologs were 3-CBs, 4-CBs, and 5-CBs. The measured PCB concentrations were higher than the values of pristine sites. In order to assess the gas/particle partitioning fate, log K _P–log $P_{\rm L}^o$ , log K _P–log K _OA and the Junge–Pankow model were applied to the data. Experimental K _P was well correlated with $\log P_{\rm L}^o$ and log K _OA at p?<?0.05. Then, dry deposition fluxes were estimated using atmospheric concentrations and dry deposition velocities obtained from literature. A correlation matrix was formed for PCB homologs including 27 congeners with concurrently measured 16 polycyclic aromatic hydrocarbons (PAHs) and meteorological parameters. Most of PAH compounds were significantly correlated with 5-CBs and 6-CBs.     

Spatial and seasonal distribution of nitrate-N in groundwater beneath the rice�Cwheat cropping system of India: a geospatial analysis

Increased use of nitrogenous fertilizers in the intensively cultivated rice (Oryza sativa)?Cwheat (Triticum aestivum) cropping system (covers a 13.5-ha m area in South Asia) has led to the concentration of nitrates (NO₃-N) in the groundwater (GW) in Haryana State of India. Six districts from the freshwater zone were selected to identify factors affecting NO₃-N enrichment in GW. Water and soil samples were collected from 1,580 locations and analyzed for their chemical properties. About 3% (26,796, and 10,588 ha) of the area was estimated to be under moderately high (7.5?C10 mg l^???1) and high (>10 mg l^???1) risk categories, respectively. The results revealed that NO₃-N was 10?C50% higher during the pre-monsoon season than in the monsoon season. Nitrate-N decreased with the increase in aquifer depth (r ²?=?0.99). Spatial and proximity analyses using ArcGIS (9.2) revealed that (1) clay material in surface and sub-surface texture restricts N leaching, (2) piedmont and rolling plains act as an N sink, and (3) perennial rivers bring a dilution effect whereas seasonal rivers provide favorable conditions for NO₃ ^? enrichment. The study concludes that chemical N fertilizers applied in agro-ecosystems are not the sole factor determining the NO₃ in groundwater; rather, it is an integrated process governed by several other factors including physical and chemical properties of soils, proximity and type of river, and geomorphologic and geographical aspects. Therefore, future studies should adopt larger area (at least watershed scale) to understand the mechanistic pathways of NO₃ enrichment in groundwater and interactive role of the natural drainage system and surrounding physical features. In addition, the study also presents a conceptual framework to describe the process of nitrate formation and leaching in piedmont plains and its transportation to the mid-plain zone.     

Leaching behavior of nitrogen in a long-term experiment on rice under different N management systems

The leaching behavior of nitrogen was studied in single rice paddy production ecosystems in Tsukuba, Japan after 75 years of consistent fertilization regimes (no fertilizer, ammonium sulfate, a combination of composted rice straw with soybean cake, and fresh clover). During the 75-year period, management was unchanged with respect to rice planting density, irrigation, and net N fertilization for each field to which an N-source was added. Percolation water was collected, from May 2001 to April 2002, using porous suction cups installed in the fields at depths of 15, 40, and 60 cm. All water samples were taken to the laboratory for the measurement of both NH₄ ^?+??CN and NO₃ ^????CN concentrations using a continuous-flow nitrogen analyzer. The result indicated that there were significant differences in N leaching losses between treatments during the rice growing season. Total N leaching was significantly lower with the application of composted rice straw plus soybean cake (0.58 kg N ha^???1) than with ammonium sulfate (2.41 kg N ha^???1), which resulted in N leaching at a similar level to that with the fresh clover treatment (no significant difference). The majority of this N leaching was not due to NO₃ ^????CN loss, but to that of NH₄ ^?+??CN. The mean N leaching for all fertilizer treatments during the entire rice growing season was 1.58 kg N ha^???1. Composted rice straw plus soybean cake produced leaching losses which were 65?C75% lower than those with the application of fresh clover and ammonium sulfate. N accumulation resulting from nitrification in the fallow season could be a key source of nitrate?CN leaching when fields become re-flooded before rice transplanting in the following year; particular attention should be paid to this phenomenon.     

Relationships of relative humidity with PM<Subscript>2.5</Subscript> and PM<Subscript>10</Subscript> in the Yangtze River Delta,China

Severe particulate matter (PM, including PM_2.5 and PM₁₀) pollution frequently impacts many cities in the Yangtze River Delta (YRD) in China, which has aroused growing concern. In this study, we examined the associations between relative humidity (RH) and PM pollution using the equal step-size statistical method. Our results revealed that RH had an inverted U-shaped relationship with PM_2.5 concentrations (peaking at RH = 45–70%), and an inverted V-shaped relationship (peaking at RH = 40 ± 5%) with PM₁₀, SO₂, and NO₂. The trends of polluted-day number significantly changed at RH = 70%. The very-dry (RH < 45%), dry (RH = 45–60%) and low-humidity (RH = 60–70%) conditions positively affected PM_2.5 and exerted an accumulation effect, while the mid-humidity (RH = 70–80%), high-humidity (RH = 80–90%), and extreme-humidity (RH = 90–100%) conditions played a significant role in reducing particle concentrations. For PM₁₀, the accumulation and reduction effects of RH were split at RH = 45%. Moreover, an upward slope in the PM_2.5/PM₁₀ ratio indicated that the accumulation effects from increasing RH were more intense on PM_2.5 than on PM₁₀, while the opposite was noticed for the reduction effects. Secondary transformations from SO₂ and NO₂ to sulfate and nitrate were mainly responsible for PM_2.5 pollution, and thus, controlling these precursors is effective in mitigating the PM pollution in the YRD, especially during winter. The conclusions in this study will be helpful for regional air-quality management.     

The impact assessment of Diwali fireworks emissions on the air quality of a tropical urban site, Hyderabad, India, during three consecutive years

Diwali is one of the largest festivals for Hindu religion which falls in the period October–November every year. During the festival days, extensive burning of firecrackers takes place, especially in the evening hours, constituting a significant source of aerosols, black carbon (BC), organics, and trace gases. The widespread use of sparklers was found to be associated with short-term air quality degradation events. The present study focuses on the influence of Diwali fireworks emissions on surface ozone (O₃), nitrogen oxides (NO _x ), and BC aerosol concentration over the tropical urban region of Hyderabad, India during three consecutive years (2009–2011). The trace gases are analyzed for pre-Diwali, Diwali, and post-Diwali days in order to reveal the festivity’s contribution to the ambient air quality over the city. A twofold to threefold increase is observed in O₃, NO _x , and BC concentrations during the festival period compared to control days for 2009–2011, which is mainly attributed to firecrackers burning. The high correlation coefficient (~0.74) between NO _x and SO₂ concentrations and higher SO₂/NO _x (S/N) index suggested air quality degradation due to firecrackers burning. Furthermore, the Cloud–Aerosol Lidar and Infrared Pathfinder Satellite Observation-derived aerosol subtyping map also confirmed the presence of smoke aerosols emitted from firecrackers burning over the region. Nevertheless, the concentration level of pollutants exhibited substantial decline over the region during the years 2010 and 2011 compared to 2009 ascribed to various awareness campaigns and increased cost of firecrackers.     

Assessment of environmental impact on air quality by cement industry and mitigating measures: a case study

In this study, environmental impact on air quality was evaluated for a typical Cement Industry in Nigeria. The air pollutants in the atmosphere around the cement plant and neighbouring settlements were determined using appropriate sampling techniques. Atmospheric dust and CO₂ were prevalent pollutants during the sampling period; their concentrations were recorded to be in the range of 249–3,745 mg/m³ and 2,440–2,600 mg/m³, respectively. Besides atmospheric dust and CO₂, the air pollutants such as NO _x , SO _x and CO were in trace concentrations, below the safe limits approved by FEPA that are 0.0062–0.093 mg/m³ NO _x , 0.026 mg/m³ SO _x and 114.3 mg/m³ CO, respectively. Some cost-effective mitigating measures were recommended that include the utilisation of readily available and low-cost pozzolans material to produce blended cement, not only could energy efficiency be improved, but carbon dioxide emission could also be minimised during clinker production; and the installation of an advance high-pressure grinding rolls (clinker–roller-press process) to maximise energy efficiency to above what is obtainable from the traditional ball mills and to minimise CO₂ emission from the power plant.     

Seasonal trends of atmospheric nitrogen dioxide and sulfur dioxide over North Santa Clara, Cuba

Atmospheric nitrogen dioxide (NO₂) and sulfur dioxide (SO₂) levels were monitored simultaneously by means of Radiello passive samplers at six sites of Santa Clara city, Cuba, in the cold and the warm seasons in 2010. The dissolved ionic forms of NO₂ and SO₂ as nitrate and sulfite plus sulfate, respectively, were determined by means of ion chromatography. Analysis of NO₂ as nitrite was also performed by UV–Vis spectrophotometry. For NO₂, significant t tests show good agreement between the results of IC and UV–Vis methods. The NO₂ and SO₂ concentrations peaked in the cold season, while their minimum levels were experienced in the warm season. The pollutant levels do not exceed the maximum allowable limit of the Cuban Standard 39:1999, i.e., 40 μg/m³ and 50 μg/m³ for NO₂ and SO₂, respectively. The lowest pollutant concentrations obtained in the warm season can be attributed to an increase in their removal via precipitation (scavenging) while to the decreased traffic density and industrial emission during the summer holidays (e.g., July and August).     

Heavy metals in the habitat and throughout the food chain of the Neotropical otter, Lontra longicaudis, in protected Mexican wetlands

Top predators like the Neotropical otter, Lontra longicaudis annectens, are usually considered good bioindicators of habitat quality. In this study, we evaluated heavy metal contamination (Hg_tot, Pb, Cd) in the riverine habitat, prey (crustaceans and fish), and otter feces in two Ramsar wetlands with contrasting upstream contamination discharges: Río Blanco and Río Caño Grande in Veracruz, Mexico, during the dry, the wet, and the nortes seasons. Most comparisons revealed no differences between sites while seasonal differences were repeatedly detected for all of the compartments. Higher concentrations of Pb during the dry season and of Cd during the wet season in otter feces mirrored differences detected in the most seasonally consumed prey. Compared with fecal methylmercury values reported for the European otter (0.25–0.75 mg kg^?1) in unprotected areas, the Hg_tot levels that we measured were lower (0.02–0.17 mg kg^?1). However, Pb (117.87 mg kg^?1) and Cd (9.14 mg kg^?1) concentrations were higher (Pb, 38.15 mg kg^?1 and Cd, 4.72 mg kg^?1) in the two Ramsar wetlands. Protected areas may shelter species, but those with water-linked diets may suffer the effect of chemicals used upstream.