Total Nitrate Concentrations Research Articles

Electrochemical treatment of organic pollutants in landfill leachate using a three-dimensional electrode system

The use of three-dimensional electrode is a new electrochemical oxidation technology for landfill leachate treatment. In this study, a particle electrode was developed using Fe/C granules, which were suspended between the cathode and the anode to create a three-dimensional electrode. The three-dimensional electrode activated sodium persulfate to treat landfill leachate. Fe/C granules were prepared by incorporating iron filings and hydrothermally carbonized biochar into alginate beads. The optimal parameters of the three-dimensional electrode for chemical oxygen demand (COD) removal from landfill leachate were determined based on a series of single factor experiments as an operating voltage of 5V, a sodium persulfate concentration of 28mM, and 1g of Fe/C granules. Treatment with the three-dimensional electrode at optimized conditions achieved 72.9% removal of COD and 99.9% removal of ammonia nitrogen, resulting in landfill leachate being clear and transparent. The changes in total organic carbon, nitrite, and nitrate concentrations indicated that most organic pollution and ammonia nitrogen were converted into CO2 and N2. This study provides an alternative technology for the treatment of refractory organic pollutants.

Evaluation of trophic status of Deudap Beach and Lhok Reudeup Beach, Nasi Island, Aceh Province, based on nitrate and phosphate concentration, and chlorophyll-a abundance.

The investigation of the trophic status based on the nitrate-phosphate correlation and chlorophyll-a abundance in Deudap beach and Lhok Reudup beach, Pulau Nasi, Aceh were carried out in November 2018. Determination of sampling location based on purposive sampling method. The total nitrate, total phosphate concentration, and chlorophyll-a abundance determined by Ultra Violet-Visible (UV-Vis) spectrophotometre which was confirmed from the real-time NOAA database. The results of the chlorophyll-a abundance analysis showed that the abundance of chlorophyll-a in the surface layer ranges 0.7 - 0.11 μg / L. Total nitrate and total phosphate concentrations at deudap beach and lhok reudup in the surface layer ranges 260 - 183 μg / L and 9.4 - 6.8 μg / L. Furthermore, the results indicate that the phenomenon of the chlorophyll-a abundance is closely related to the availability of the macronutrient of nitrate and phosphate. Based on the correlation between total nitrate-phosphate and chlorophyll-a abundance in deudap beach and lhok reudup, Nasi Island are included in the category of oligotrophic waters.

Coating of Rh/Mg/Al Hydrotalcite‐Like Materials on FeCrAl Fibers by Electrodeposition and Application for Syngas Production

Metallic fibers are promising supports to develop structured catalysts due to their high thermal stability, mechanical strength and geometrical surface area. However, such a high surface area is usually associated with small individual fibers and tiny pores, leading to pore blockage during coating process. Herein, electrodeposition is investigated as a simple way to deposit Rh/Mg/Al hydrotalcite‐like materials on FeCrAl fibers. Several trials are performed to optimize the synthesis conditions in the electro‐base generation method, using nitrates as precursors, focusing on total metal nitrate concentration and synthesis time. Combinations of both parameters are screened to find a balance between coating quality and loading. A low electrolyte concentration (e.g., <0.06 m) requires longer synthesis time to obtain an appropriate loading without pore blockage, whereas a high concentration (e.g., 0.10 m) may cause the deposition of undesired Rh0 particles. Tailoring the solid loading and decreasing the cracks in electrodeposited samples results in a quite stable coating during a further thermal treatment step to transform hydrotalcite‐like compounds into oxide‐ and spinel‐based catalysts. All tested catalysts are active in the catalytic partial oxidation of methane at gas hourly space velocity (GHSV) of 351 000 h−1, although their catalytic activities significantly depend on the coating properties.

Enhancing the production of scopoletin and quercetin 3-O-β-d-glucoside from cell suspension cultures of Tilia americana var. mexicana by modulating the copper and nitrate concentrations

The aerial tissues of Tilia americana var. mexicana produce compounds with anxiolytic activity, such as quercetin 3-O-β-d-glucoside and tiliroside, in addition to ones with anti-inflammatory properties, such as scopoletin. These three compounds were initially identified in callus cultures of apical buds. In the present study, suspension cultures from leaf explant callus were established; the accumulation of scopoletin and quercetin 3-O-β-d-glucoside in these cultures were found to be cell-growth-associated using cell growth and active compound-production kinetics assays. The effects of varying the nitrate and copper concentrations in Murashige and Skoog (MS, 27.4 mM total nitrates and 0.01 µM copper) medium on the growth of a suspension culture of T. americana cells and on the production of active compounds were tested by means of central composite design (CCD) generally used in the response surface methodology (RSM). Cell growth, measured as maximal biomass, improved when the total nitrate concentration decreased in the MS medium to 13.7 mM (p < 0.01) regardless of the copper concentration. As a phytoalexin, scopoletin accumulated rapidly in plants after pathogen infection, in the suspension cultures scopoletin yield was stimulated by increased copper concentration to 1.2 μM (p < 0.01). According to the C:N hypothesis, the carbon excess generated by nitrates reduced to 8.03 mM (p < 0.01) stimulated the production of quercetin 3-O-β-d-glucoside. Cell suspension of T. americana represents a potential biotechnological alternative for industrial exploitation in a stirred-tank bioreactor using a two-phase process: (1) the first step will be to grow the cell suspension, (2) the second stage will consist in handle the suspension culture towards the production of anxiolytic compounds or towards the production of anti-inflammatory compounds. As well as to evaluate another elicitors to stimulate tiliroside production in the T. americana suspension cultures.

Potential influence of Yucca extract as feed additive on greenhouse gases emission for a cleaner livestock and aquaculture farming - A review

Abstract Creating a balance between minimizing environmental impacts and intensification, of livestock and aquaculture, is important to ensure sustainable animal-protein production. Application of natural additives that are suitable for cleaner animal production is a necessity. Yucca schidigera is capable of this and because it could grow in desert area, makes it a potential asset in the face of global warming-related climate changes. Thirty-five studies were used as data, which include in vitro and in vivo evaluations. About 43%, 28.6% and 31% were proportion of ruminant, monogastric and aquaculture species used for this study. Yucca schidigera showed that it is capable of reducing aerial ammonia concentration in pens, and ammonia odour from manure. In ruminant, Yucca could reduce methane emission, lower nitrous oxide emission, reduce urinary and fecal nitrogen. Yucca extract could be used to improve water quality by reducing the concentration of total ammonia nitrogen and nitrate in fresh and marine water used for aquaculture. Therefore, to reduce livestock footprint, Yucca may be included in the diet of cattle, sheep, goat, horses, rabbit, fishes, and shrimps with a positive result. The reviewed publications provide strong support for the use of Yucca extract as feed additive to reduce nutrient excretion and environmental impact of animal-protein production. This study, however, shows that there is need for more in vivo studies of Yucca in swine rabbit, horses and even poultry.

Untapped potential of zeolites in optimization of food waste composting

This study aims to examine the effect of zeolites in optimizing the process of food waste composting. A novel method of sequential hydrothermal was introduced to modify the natural zeolite and apply to in-vessel compost bioreactors. Raw and modified natural zeolites were applied at 10 and 15% (w/w) of the total waste and compared with un-amended control trial. Both raw and modified zeolites affected the composting process, but the notable results were observed for modified natural zeolite. The results for compost stability parameters were prominent at 15% modified natural zeolite concentration. The rapid and long-term thermophillic temperature and moisture content reduction to the optimum range was observed for modified natural zeolite. Furthermore, the total ammonium (NH4+) and nitrate (NO3−) concentration in modified natural zeolite were increased by 11.1 and 21.5% respectively as compared to raw zeolite. Compost stability against moisture contents (MC), electrical conductivity (EC), organic matters (OM), total carbon (TC), mineral nitrogen, nitrification index (NI) and germination index (GI) was achieved after 60 days of composting that was in accordance with the international compost quality standards. The findings of this study suggested the suitability of modified natural zeolite addition at 15% to the total waste as the optimum ratio for the composting of food waste in order to achieve a stable nutrient-rich compost.

Land cover impacts on storm flow suspended solid and nutrient concentrations in southwest Ohio streams.

Impacts between urban and agricultural land cover on storm flow water quality are poorly understood for the Eastern Corn Belt Ecoregion in SW Ohio. Storm flow water samples were collected from May 2017 to October 2017 across seven SW Ohio watersheds which ranged in urban land cover from 6% to 92% and in agricultural land cover from 4% to 70%. Two watersheds contained water resource recovery facilities (WRRFs). Percent agricultural land cover in a watershed and storm magnitude were primary explanatory variables for total suspended solid and total phosphorus concentrations. Total nitrogen, nitrate, and phosphate concentrations were primarily explained by the presence of WRRFs and percent agricultural land cover. Increased dissolved nutrient concentrations in watersheds with WRRFs indicate that WRRFs in the study area are ineffectively removing nitrate and phosphate from effluent. Results suggest that to improve water quality during storm flows, additional management efforts need to be focused on agricultural watersheds and WRRFs. PRACTITIONER POINTS: Storm flow water quality in the study area is significantly affected by land cover, WRRF Q, and storm Q. TSS and TP concentrations are best explained by percent of agricultural land cover in a watershed and magnitude of storms. TN, NO3 -N, and concentrations are best explained by WRRF Q, followed by the percent agricultural land cover. This study shows that agricultural land cover and WRRFs play a significant role in water quality degradation in SW Ohio.

Evaluating the Impacts of Integrated Pollution on Water Quality of the Trans-Boundary Neris (Viliya) River

The trans-boundary area between the Europe Union and other countries is highly susceptible to changes in water quality and variations in the potential pollution load that could influence its eco-systems significantly. The Neris (Viliya) River is one of the biggest surface water bodies in Lithuania and Belarus with an ecologically important area protected by international legislation. The study was aimed at evaluating the impacts of integrated pollution on water quality of the Neris River taking into account different storm-water flows and ecological scenarios. For this purpose, qualitative and quantitative statistical evaluation was set up and calculation was done; different integrated pollution loads of the catchment area were estimated. The evaluation considered a decrease in river discharge due to changes in the regional storm-water flow and technological development that should lead to the growing covered surface and a reduction in the untreated storm-water flows. The obtained results indicated that, in the case of storm-water treatment, the total nitrate and phosphate concentrations will decrease, while in the cases of changes in combined suspended solid, the concentration of nutrients will decrease. Thus, a trans-boundary storm-water treatment plant of the Viliya River is required as it should eliminate pollution accumulation and restore its acceptable environmental status. A coordinated international project for the entire catchment of the Neris (Viliya) River based on the specifications and requirements of the EU Water Framework Directive (EU 2000) should be developed and implemented. Subsequently, ecological river-use policies should be established at the international level, which should offer considerable perspectives for the sustainable development of the area.

Spatial distribution and habitat suitability of Biomphalaria straminea, intermediate host of Schistosoma mansoni, in Guangdong, China

BackgroundBiomphalaria straminea is an invasive vector in China, posing a significant threat to public health. Understanding the factors affecting the establishment of this snail is crucial to improve our ability to manage its dispersal and potential risk of schistosomiasis transmission. This study sought to determine the spatial distribution of B. straminea in mainland China and whether environmental factors were divergent between places with and without B. straminea.MethodsA malacological survey of B. straminea was conducted in Guangdong Province, China. Snails were identified using anatomical keys. Water and sediment samples were taken, and their physicochemical properties were analyzed using national standard methods. Landscape and climatic variables were also collected for each site. We compared the environmental characteristics between sites with and without B. straminea using Mann-Whitney U test. We further used generalized linear mixed models to account for seasonal effects.ResultsB. straminea was found at six sites, including one in Dongguan and five in Shenzhen. Probability map found a hot spot of B. straminea distribution at Shenzhen and Hong Kong. Sites occupied by B. straminea were characterized by higher median altitude, mean annual precipitation and moderate temperature. Water with snails had higher median concentrations of total nitrogen, nitrate and nitrites, ammoniacal nitrogen, calcium, zinc and manganese but lower dissolved oxygen and magnesium. Sediments with snails had higher median copper, zinc and manganese. B. straminea was associated with maximum temperature of the warmest month (pMCMC < 0.001) and sediment zinc (pMCMC < 0.001).ConclusionsB. straminea is distributed in Shenzhen and its surrounding areas in Guangdong, China. Sites with and without B. straminea differed in the maximum temperature of the warmest month and sediment zinc. Surveillance should be continued to monitor the dispersal of this snail in China.

Behavior of total peroxy and total organic nitrate concentrations at Suzu on the Noto Peninsula, Japan: Long-range transport and local photochemical production

We performed continuous observations (2012–2015) of total peroxy nitrates (PNs) and total organic nitrates (ONs) at Suzu on the Noto peninsula, Japan. It was found that PNs and ONs showed similar seasonal variations with maximum concentrations in spring and minimum concentrations in summer. Concentrations of PNs and ONs were high for air masses originating from the Asian continent from winter to spring, whereas they were independent of air mass origin from spring to summer. In summer, PNs and ONs indicated similar diurnal variations with maximum concentrations during daytime and minimum concentrations during nighttime. Such diurnal variations of PNs and ONs were small in winter. Diurnal variations of PNs in spring were similar to those in summer, whereas such diurnal variations were not observed for ONs in spring. In the cold season, PNs and ONs have long atmospheric lifetimes and local photochemical production rates of PNs and ONs are slow, whereas the converse is true in the warm season. Therefore, concentration variations of PNs and ONs are governed primarily by long-range transport in the cold season and by local photochemical production in the warm season.

Phytoremediation of Eel (Anguilla bicolor bicolor) rearing wastewater using amazon sword (Echinodorus amazonicus ) and water jasmine (Echinodorus palaefolius)

Management of aquaculture wastewater is still the major problems in fisheries, especially in intensive systems. Intensively aquaculture activities often increase organic matter and nutrients (N and P) in the water. The study was conducted to evaluate the phytoremediator performance of Echinodorus amazonicus and Echinodorus palaefolius in removing inorganic nitrogen and orthophosphate from aquaculture wastewater with the recircula­tion system. This study used a completely randomized design with three treatments and 3 replications. The treatments of this study were P1: E. amazonicus, P2: E. palaefolius and P3: control (without aquatic plants). The tested fish were elvers which average weight 6.98 ± 0.19 g, and fish density was 4 gL-1. Elvers reared in an aquarium that containing 48 L in a recirculation system. The paste feed which protein level of 45.25% was given at satiation 3 times/day. Elvers reared for 60 days. The results showed that E. palaefolius significantly reduced concentrations of total ammonia nitrogen (TAN), nitrite (NO2), nitrate (NO3) and orthophosphate (PO4) with an efficiency of 27.10 ± 2.42%; 45.03 ± 9.77%; 20.94 ± 1.29% and 14.19 ± 3.05%, respectively higher than E. amazonicus and control. The best result of elver’s performance (SGR and FCR) was in treatment P2 (E. palaefolius), i.e. 1.19 ± 0.18% and 1.57 ± 0.30. Based on the results of this study, it can be concluded that the use of E. palaefolius as phytoremediator in eel culture with recirculation system can removed inorganic nitrogen and orthophosphate more optimal compared to other treatment.

Nitrogen and phosphorous budgets for integrated culture of whiteleg shrimp Litopenaeus vannamei with red seaweed Gracilaria corticata in zero water exchange system

Abstract In this study, a 2×3 factorial design with two levels of shrimp density (25 and 50 shrimp per m-2) and three levels of red algae density (0, 200 and 400g per m-2) was applied to calculate nitrogen and phosphorous budgets in integrated culture of Litopenaeus vannamei with Gracilaria corticata during 45 days under zero water exchange system. Juvenile of L.vannamei (5.82 ± 0.11 g) and G.corticata were cultured in 18 round 1 m3 poly ethylene tanks. Water temperature, dissolved oxygen (DO), pH and salinity were measured each 3- day. Results indicated that shrimp density had a significant effect on pH and DO in the morning and in the afternoon. The algae density didn’t have a significant effect on pH and DO culturing tanks (p > 0.05). According to The results of this study, the main source of nitrogen and phosphorus input to the tanks during a 45- day culturing period was from feed. Shrimp and algae densities significantly affect the concentration of total ammonia, nitrite, nitrate and phosphate in water and an increase in shrimp density led to increase of these compounds whereas, increasing the algae density led to reduction of these compounds. Results indicated that increasing the density of G.corticata in all treatments, led to increase in biomass of harvested shrimp and the co-culture of G. corticata with L.vannamei decrease the amount of nitrogen and phosphorus in both water and sediments and improve the water quality of L.vannamei culture.

Response of Potato Plants to Sources and Rates of Potassium Fertilizer

Two field experiments were carried out at a Private Farm in Meet Habib Village, Gharbia Governorate, during Winter seasons of 2015/2016 and 2016/2017 to determine the influence of potassium fertilizers levels, foliar application treatments and interactions on growth, yield and some chemical constituents in both leaves and tubers of potato cv. Spunta. Mineral fertilizing with 75 % of the recommended doses recorded the highest values of vegetative growth characters, total marketable tubers yield/fed, total soluble solids percentage (TSS) and vitamin-C content in fresh potato in both seasons. While, the highest values of total carbohydrates and starch percentages, nitrite and nitrate concentrations in fresh potato tubers were obtained from fertilizing with 100 % of the recommended doses in both seasons. Total sugars percentage in fresh potato tubers had reverse trend of all studied characters in both seasons. Foliar spraying potato plants four times with commercial fertilizer (MegaPot as a source of nitrogen, potassium and sulphur) at the rate of 1.5 g/liter water exceeded other foliar application treatments and produced the highest values of vegetative growth characters, yield and quality parameters of tubers, except total sugars percentage, nitrite and nitrate concentrations in fresh potato tubers. It can be concluded that mineral fertilizing potato by 75 % of the recommended dose as a soil application in addition to foliar spraying four times with commercial fertilizer MegaPot (as a source of nitrogen, potassium and sulphur) at the rate of 1.5 g/liter water in each spraying is the best to obtain high growth, yield, chemical composition and quality of potato Spunta cultivar.

Tracking the Release of Soil Nitrate and Labile C in A Legume-Maize Rotation in Zimbabwe

This study compared the effect of a weedy fallow (5.2 t/ha biomass), a velvet bean (Mucuna pruriens) cut for hay (7.2 t/ha biomass) and a green-manured M. pruriens (6.49 t/ha biomass) on the dynamics of soil N and C in a maize crop. An on-farm, farmer participatory experiment was established on a farmer’s field in Wedza District, Zimbabwe. Soil mineral N and labile carbon were determined at intervals upto 120 cm depth, at maize planting and at 1 and 2 weeks after planting. Before planting, the soil mineral N content ranged from 28 kg N/ha after weed fallow to 107 kgN/ha following M. pruriens. Total nitrate concentration was highest in the 0-15 cm depth of the M. pruriens treatments in the pre-planting sampling, but following rainfall and maize planting, nitrate concentration declined rapidly. By 2 weeks after planting, 7.5 and 13.5 kg N/ha remained in the 0-120 cm soil depth of the weedy fallow and green-manured M. pruriens, respectively. Improving synchrony of nutrient release and uptake is critical when applying high quality residues which breakdown relatively slowly. This could result in significant inputs of C, release nutrients more slowly and reduce soil nutrient losses.

Reconceptualizing INRM in understanding environmental risks from food production systems

Sustainable agri-development is composed of soil fertility maintenance, nutrient use efficiency and resource use efficiency. In this regard, the present study aims to address the complex dynamics of farm-soil and the water nexus for integrated natural resource management by understanding the fertilizer use decision of farmers. In addition to the monitoring of soil quality parameters, that is, the total nitrogen and nitrate concentrations, factor analysis was used to explore the drivers of high fertilizer use in the most agriculturally intensive region of India. The results classified economic benefits, intrinsic and extrinsic motivations, resource-related aspects, institutional set-up and passivity towards environmental quality as major entry points for integrated natural resource management. Although the economic benefit in the form of the affordability of nitrogenous fertilizers was found to be the most critical rationale for fertilizer use, passivity towards environmental quality emerged as a factor of interest. Because short-term economic benefits outweigh concerns for environmental quality, our research suggests that outreach educational programs on sustainable farm practices can be instrumental in resource management. Support of the farming community by governmental/non-governmental agricultural agencies to formulate site-specific recommendations can significantly mitigate fertilizer-induced non-point pollution.

Benefits to decomposition rates when using digestate as compost co-feedstock: Part II – Focus on microbial community dynamics

Linkage between composting reactor performance and microbial community dynamics was investigated during co-composting of digestate and fresh feedstock (organic fraction of municipal solid waste) using 25L reactors. Previously, the relationship between composting performance and various physicochemical parameters were reported in Part I of the study (Arab and McCartney, 2017). Three digestate to fresh feedstock ratios (0, 40, and 100%; wet weight basis) were selected for analysis of microbial community dynamics. The 40% ratio was selected because it was found to perform the best (Arab and McCartney, 2017). Illumina sequencing results revealed that the reactor with a greater composting performance (higher organic matter degradation and higher heat generation; 40% ratio) was associated with higher microbial diversity. Two specific bacterial orders that might result in higher performance were Thermoactinomycetaceae and Actinomycetales with a higher sequence abundance during thermophilic composting phase and during the maturing composting phase, respectively. Galactomyces, Pichia, Chaetomium, and Acremonium were the four fungal genera that are probably also involved in higher organic matter degradation in the reactor with better performance. The redundancy analysis (RDA) biplot indicated that among the studied environmental variables, temperature, total ammonia nitrogen and nitrate concentration accounted for much of the major shifts in microbial sequence abundance during the co-composting process.

Potential Drivers of the Level and Distribution of Nitrogen in the Hyporheic Zone of Lake Taihu, China

The hyporheic zone is the connection between surface water and groundwater that often plays an important function in nutrient transport and transformation, and acts as an active source of or sink for nutrients to the surface water, depending on its potential water flow patterns. Bottom surface water and sediments in the shallow hyporheic zone (approximately 100 cm depth) were sampled at 12 sites near the shoreline and two sites at the center of Lake Taihu (China) during spring and winter of 2016. Concentrations of total nitrogen, ammonium, nitrate, and nitrite in the bottom surface water and porewater (obtained from sediments using a frozen centrifugation method) were analyzed in a laboratory to establish the nitrogen distribution and potential drivers. The results show that, in general, the quality of bottom water and porewater near the shoreline was poor compared to that at the center, and it gradually improved from the northwestern to the southeastern zones of Lake Taihu. No significant relationship in nitrogen concentration was found between the bottom water and porewater in surface sediments. Nitrogen concentrations in porewater differed between sampling sites and sediment depths in Lake Taihu. Vertical profiles of nitrogen in porewater and differences in nitrogen between the winter and spring seasons indicated that potential upwelling water flow occurred in the hyporheic zone in the south, west, north, and center zones of Lake Taihu, but potentially weak water flow in variable directions likely occurred in the east zone. A strong reducing environment dominated the deep parts of the hyporheic zone (i.e., below 40 cm depth), while a weak oxidizing environment dominated the shallow parts. Furthermore, the decreasing total nitrogen and ammonium nitrogen from the deep to shallow depths in the hyporheic zones in the south, west, north, and center zones indicated that potential anammox and/or denitrification processes occurred. In the east zone, potential weak nitrification processes occurred in the hyporheic zone, and plant fixation and sedimentation of nitrogen also contributed to the surface sediments. In conclusion, the hyporheic zone near the shoreline in the south, west, and north sites of Lake Taihu acts as an active source of nitrogen for the lake water due to potential upwelling water flows, whereas the east site acts as an active source or sink due to seasonally variable directions in water flow. Water flow and biogeochemistry in the hyporheic zone jointly influence nutrient distribution in the hyporheic zone and even switch or alternate the source/sink function of sediment in surface water.

Fine particle pH and gas–particle phase partitioning of inorganic species in Pasadena, California, during the 2010 CalNex campaign

Abstract. pH is a fundamental aerosol property that affects ambient particle concentration and composition, linking pH to all aerosol environmental impacts. Here, PM1 and PM2. 5 pH are calculated based on data from measurements during the California Research at the Nexus of Air Quality and Climate Change (CalNex) study from 15 May to 15 June 2010 in Pasadena, CA. Particle pH and water were predicted with the ISORROPIA-II thermodynamic model and validated by comparing predicted to measured gas–particle partitioning of inorganic nitrate, ammonium, and chloride. The study mean ± standard deviation PM1 pH was 1.9 ± 0.5 for the SO42−–NO3−–NH4+–HNO3–NH3 system. For PM2. 5, internal mixing of sea salt components (SO42−–NO3−–NH4+–Na+–Cl−–K+–HNO3–NH3–HCl system) raised the bulk pH to 2.7 ± 0.3 and improved predicted nitric acid partitioning with PM2. 5 components. The results show little effect of sea salt on PM1 pH, but significant effects on PM2. 5 pH. A mean PM1 pH of 1.9 at Pasadena was approximately one unit higher than what we have reported in the southeastern US, despite similar temperature, relative humidity, and sulfate ranges, and is due to higher total nitrate concentrations (nitric acid plus nitrate) relative to sulfate, a situation where particle water is affected by semi-volatile nitrate concentrations. Under these conditions nitric acid partitioning can further promote nitrate formation by increasing aerosol water, which raises pH by dilution, further increasing nitric acid partitioning and resulting in a significant increase in fine particle nitrate and pH. This study provides insights into the complex interactions between particle pH and nitrate in a summertime coastal environment and a contrast to recently reported pH in the eastern US in summer and winter and the eastern Mediterranean. All studies have consistently found highly acidic PM1 with pH generally below 3.

Effect of packing material on organic matter removal efficiency in an anaerobic–aerobic baffled bioreactor

ABSTRACTThe aim of the present work was to study the effect of packing material on the organic matter removal efficiency (OMRE) in an anaerobic–aerobic baffled bioreactor (AAB). For this purpose, two different experiments were conducted with two types of packing material: activated carbon (AC) particles and polyurethane foam (PF). The system consisted of two treatments; the first one was anaerobic, where hydrolysis, acetogenesis and methanogenesis took place. In anaerobic chambers, there were no packing materials and the operating conditions were the same in both experiments. The second treatment was aerobic and both materials were placed at different times as a bedding. The parameters measured were chemical oxygen demand (COD), dissolved chemical oxygen demand (CODd), total organic carbon (TOC), nitrate concentration (NO3–), ammonium concentration (NH4+), electric conductivity (σ), alkalinity (Alky) and hydrogen potential (pH). Paired t-Student test showed that there was no significant difference in the OMRE in anaerobic treatment, whereas there was in aerobic treatment, due to the effect of packing material. NH4+ and NO3– showed a negative Pearson correlation in both experiments, indicating the presence of the nitrification process in the aerobic chamber. AAB packed with PF had better performance at obtaining an OMRE of around 63%, whereas AAB packed with AC presented an OMRE of around 51%.

Cambios en la composición de la comunidad bacteriana de diferentes hábitats a lo largo de un río contaminado (Río Suquía, Córdoba, Argentina)

The objective of the present study was to investigate the influence of environmental conditions on the bacterial community composition water, sediment and riparian soil during different water flow periods. For this purpose, samples of three habitats (water, sediment and riparian soil) were collected from five polluted sites and one reference site along the Suquia River during high and low water flow periods. The pH, dissolved oxygen, conductivity and water temperature were measured in situ, with total organic carbon content, nitrate and ammonia concentration being evaluated for all samples. In addition, pH, conductivity and total N were determined the sediment and riparian soil samples, and the bacterial community composition of water, sediments and riparian soil samples was monitored using restriction fragment length polymorphism of the 16S rRNA gene. The results showed that the bacterial community composition of water was different from that of sediments or riparian soil. A redundancy analysis indicated that the changes the bacterial community composition the Suquia River were primarily correlated with variations dissolved oxygen, conductivity and pH. The water bacterial community composition was very variable among sites and water flow periods, while that of sediments differed according to the water flow period, which was associated with temperature variation. Lastly, riparian soil, differences were found the bacterial community composition of the sites located before and after Cordoba city. Our findings suggest distinct distribution patterns the bacterial community compositions of the three habitats evaluated.