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Sian F Henley, Elizabeth M Jones, Hugh J Venables, Michael P Meredith, Yvonne L Firing, Ribanna Dittrich, Sabrina Heiser, Jacqueline Stefels, Julie Dougans
The West Antarctic Peninsula shelf is a region of high seasonal primary production which supports a large and productive food web, where macronutrients and inorganic carbon are sourced primarily from intrusions of warm saline Circumpolar Deep Water. We examined the cross-shelf modification of this water mass during mid-summer 2015 to understand the supply of nutrients and carbon to the productive surface ocean, and their subsequent uptake and cycling. We show that nitrate, phosphate, silicic acid and inorganic carbon are progressively enriched in subsurface waters across the shelf, contrary to cross-shelf reductions in heat, salinity and density...
June 28, 2018: Philosophical Transactions. Series A, Mathematical, Physical, and Engineering Sciences
Xiaoxu Jia, Yuanjun Zhu, Laiming Huang, Xiaorong Wei, Yunting Fang, Lianhai Wu, Andrew Binley, Mingan Shao
Nitrogen (N) stored in deep profiles is important in assessing regional and/or global N stocks and nitrate leaching risk to groundwater. The Chinese Loess Plateau, which is characterized by significantly thick loess deposits, potentially stores immense stocks of mineral N, posing future threats to groundwater quality. In order to determine the vertical distributions of nitrate and ammonium content in the region, as well as to characterize the potential accumulation of nitrate in the deep loess profile, we study loess samples collected at five sites (Yangling, Changwu, Fuxian, An'sai and Shenmu) through a 50 to 200m loess profile...
August 15, 2018: Science of the Total Environment
S W How, S Y Lim, P B Lim, A M Aris, G C Ngoh, T P Curtis, A S M Chua
Intensive aeration for nitrification is a major energy consumer in sewage treatment plants (STPs). Low-dissolved-oxygen (low-DO) nitrification has the potential to lower the aeration demand. However, the applicability of low-DO nitrification in the tropical climate is not well-understood. In this study, the potential of low-DO nitrification in tropical setting was first examined using batch kinetic experiments. Subsequently, the performance of low-DO nitrification was investigated in a laboratory-scale sequential batch reactor (SBR) for 42 days using real tropical sewage...
May 2018: Water Science and Technology: a Journal of the International Association on Water Pollution Research
Miguel Martínez-Jardines, Emmanuel Pérez-Alfaro, R O González-Robles, Anne-Claire Texier, Flor Cuervo-López
The metabolic and kinetic behaviour of a nitrification process in presence of 2-chlorophenol (2-CP) was evaluated in two sequencing batch reactors (SBR1, SBR2) inoculated with nitrifying sludge previously exposed to phenolic compounds. The SBR1 was inoculated with sludge previously exposed to 2-CP, while the SBR2 was inoculated with sludge previously exposed to p-cresol. An inhibitory effect of 20 mg 2-CP-C/L on both nitrification processes was observed, as specific rates decreased according to a control assay in absence of 2-CP...
May 14, 2018: Environmental Technology
Koki Maeda, Fumihito Miyatake, Ryoki Asano, Kei-Ichi Nakajima, Takeki Maeda, Kazunori Iwabuchi
Animal manure is a source of the greenhouse gas nitrous oxide (N2 O), therefore understanding the mechanisms underlying its production is essential for developing mitigating strategies and sustainable livestock production system. In this study, microbial communities potentially involved in multiple emission peaks during initial stage of laboratory-scale dairy manure composting with forced aeration system were investigated. Mature compost was used for the bulking agent. Change of overall bacterial community and nitrification-denitrification gene abundance were monitored by using 16S rRNA gene amoA, nirS, nirK or nosZ genes, respectively...
April 30, 2018: Chemosphere
V Vasilaki, E I P Volcke, A K Nandi, M C M van Loosdrecht, E Katsou
Multivariate statistical analysis was applied to investigate the dependencies and underlying patterns between N2 O emissions and online operational variables (dissolved oxygen and nitrogen component concentrations, temperature and influent flow-rate) during biological nitrogen removal from wastewater. The system under study was a full-scale reactor, for which hourly sensor data were available. The 15-month long monitoring campaign was divided into 10 sub-periods based on the profile of N2 O emissions, using Binary Segmentation...
April 26, 2018: Water Research
Guowei Chen, Huan Liu, Wei Zhang, Baoguo Li, Li Liu, Gang Wang
Roxarsone is widely present in wastewaters of many animal farms in China. However, little is known about how long-term roxarsone exposure influences the nitrogen removal of biological wastewater treatment in agricultural settings. Here we investigated the nitrogen removal performance of a biological sequential batch reactor (SBR) and the changes of bacterial community, upon long-term roxarsone exposure. The long-term roxarsone dosing decreased the SBR nitrogen removal by 52.4%, with an immediate inhibition on denitrification and a delayed inhibition on nitrification...
May 10, 2018: Ecotoxicology and Environmental Safety
E P Minet, S F Ledgard, J Grant, J B Murphy, D J Krol, G J Lanigan, J Luo, K G Richards
Nitrate (NO3 - ) leaching and nitrous oxide (N2 O) emission from urine patches in grazed pastures are key sources of water and air pollution, respectively. Broadcast spraying of the nitrification inhibitor dicyandiamide (DCD) has been shown to reduce these losses, but it is expensive. As an alternative, it had been demonstrated that feeding DCD to cattle (after manual mixing with supplementary feeds) was a practical, effective and cheaper method to deliver high DCD rates within urine patches. This two-year study carried out on simulated urine patches in three application seasons (spring, summer, autumn) explored the efficacy of DCD feeding to cattle to reduce N losses from grazed pasture soil in a heavy-textured soil under temperate climatic conditions...
February 15, 2018: Science of the Total Environment
Chao Wang, Sitong Liu, Xiaochen Xu, Yongzhao Guo, Fenglin Yang, Dong Wang
The intracellular cyclic diguanylate acid (c-di-GMP) has emerged as a prominent second signal molecule that coordinates sessile-motile transition and biofilm formation in many bacteria. Herein, we study the role of c-di-GMP in affecting microbial community shifts at different pH levels during simultaneous partial nitrification, anammox and denitrification process (SNAD) in integrated fixed film activated sludge (IFAS) reactor. The results demonstrated that the contents of c-di-GMP notably decreased in suspended sludge, whereas the contents of c-di-GMP in biofilm had no significant change as pH gradually increased from 7...
May 8, 2018: Science of the Total Environment
Patrick Vanraes, Niels Wardenier, Pieter Surmont, Frederic Lynen, Anton Nikiforov, Stijn W H Van Hulle, Christophe Leys, Annemie Bogaerts
A falling film dielectric barrier discharge (DBD) plasma reactor combined with adsorption on activated carbon textile material was optimized to minimize the formation of hazardous oxidation by-products from the treatment of persistent pesticides (alachlor, diuron and isoproturon) in water. The formation of by-products and the reaction mechanism was investigated by HPLC-TOF-MS. The maximum concentration of each by-product was at least two orders of magnitude below the initial pesticide concentration, during the first 10 min of treatment...
May 3, 2018: Journal of Hazardous Materials
Shanyun Wang, Weidong Wang, Lu Liu, Linjie Zhuang, Siyan Zhao, Yu Su, Yixiao Li, Mengzi Wang, Cheng Wang, Liya Xu, Guibing Zhu
Artificial microbial nitrogen (N) cycle hotspots in the plant-bed/ditch system were developed and investigated based on intact core and slurry assays measurement using isotopic tracing technology, quantitative PCR and high-throughput sequencing. By increasing hydraulic retention time and periodically fluctuating water level in heterogeneous riparian zones, hotspots of anammox, nitrification, denitrification, ammonium (NH4+) oxidation, nitrite (NO2-) oxidation, nitrate (NO3-) reduction and DNRA were all stimulated at the interface sediments, with the abundance and activity being about 1-3 orders higher than that in non-hotspot zones...
May 11, 2018: Environmental Science & Technology
Haimeng Sun, Zhongchen Yang, Caijie Wei, Weizhong Wu
An up-flow vertical flow constructed wetland (AC-VFCW) filled with ceramsite and 5% external carbon source poly(3-hydroxybutyrate-hydroxyvalerate) (PHBV) as substrate was set for nitrogen removal with micro aeration. Simultaneous nitrification and denitrification process was observed with 90.4% NH4 + -N and 92.1% TN removal efficiencies. Nitrification and denitrification genes were both preferentially enriched on the surface of PHBV. Nitrogen transformation along the flow direction showed that NH4 + -N was oxidized to NO3 - -N at the lowermost 10 cm of the substrate and NO3 - -N gradually degraded over the depth...
April 26, 2018: Bioresource Technology
Qiulai He, Li Chen, Shujia Zhang, Li Wang, Jiawen Liang, Wenhao Xia, Hongyu Wang, Jinping Zhou
A new operating approach by reducing the aeration time while keeping high intensity was evaluated for enhanced nutrients removal and maintenance of granular stability. Three aerobic granular sequencing batch reactors (SBR) performing simultaneous nitrification, denitrification and phosphorus removal (SNDPR) were run at different aeration time (120, 90, and 60 min). Aerobic granules could remain their integrity and stability over long-term operation under high aeration intensity and different time, and shorter aeration time favored the retention of biomass, better settleability, and more production of extracellular polymeric substances (EPS)...
May 3, 2018: Bioresource Technology
Zhi Hui Wang, Jing Su, Xian Jun Jiang
Acidic forest peat soil in Xiaoxing'an Mountain was used to investigate the type and key drivers of nitrification by carrying out nitrification incubation after adding 10 mL·L-1 C2 H2 and different amounts of (NH4 )2 SO4 (0, 1.2, 6.0 mmol N·kg-1 ). Results showed that strong mineralization (0.9-1.4 mg N·kg-1 ·d-1 ) and nitrification (0.4-0.6 mg N·kg-1 ·d-1 ) after 2 weeks of incubation were observed for both nitrogen and no nitrogen treatments, and no significant difference was observed for different (NH4 )2 SO4 application treatments...
May 18, 2017: Ying Yong Sheng Tai Xue Bao, the Journal of Applied Ecology
Zhi Jie Li, Wan Qin Yang, Ruo Yang He, Li Yan Zhuang, Kai Jun Yang, Qun Liu, Ting Ting Li, Zhen Feng Xu
Warming-induced decrease in seasonal snow cover has a great potential to affect soil nitrogen cycle in alpine cold forest ecosystems. In this study, a wooden-shelter method was used to remove the snow accumulation. Soil nitrogen pools and mineralization rates in the snow removal and control plots were measured synchronously in three critical periods (early snow cover, deep snow cover and snow cover melting) in a subalpine spruce forest of western Sichuan, China. Seasonal snow cover kept soil from cold air temperature...
June 18, 2017: Ying Yong Sheng Tai Xue Bao, the Journal of Applied Ecology
Jumei Liu, Weiwei Cao, Haiming Jiang, Jing Cui, Chunfang Shi, Xiaohui Qiao, Ji Zhao, Wantong Si
Soil heavy metal pollution has received increasing attention due to their toxicity to soil microorganisms. We have analyzed the effects of heavy metal pollution on ammonia-oxidizing archaea (AOA) and ammonia-oxidizing bacteria (AOB) in soils in the vicinity of a tailings dam of Baotou region, China. Results showed that AOB were dominated with Nitrosomonas-like clusters, while AOA was dominated by group1.1b (Nitrososphaera cluster). Single Cd and Cr contents, as well as compound heavy metal pollution levels, had a significant negative impact on soil potential nitrification rate and both diversities of AOA and AOB...
May 9, 2018: Bulletin of Environmental Contamination and Toxicology
Jun Jun Ding, Wei Zhang, Yu Zhong Li, Wei Lin, Chun Ying Xu, Qiao Zhen Li
To understand the mechanisms of agricultural N2 O emission, we investigated the N2 O emission dynamics, the N2 O isotope signatures, and the site preference value under different soil water conditions in the vegetable farmland of North China, by using the stable isotope technique and the acetylene inhibition method. The results demonstrated that N2 O emission was significantly affec-ted by the water condition, and N2 O emissions from soil with water-filled pore space (WFPS) of 70% were significantly higher than that with 50% WFPS...
July 18, 2017: Ying Yong Sheng Tai Xue Bao, the Journal of Applied Ecology
Sachin Kumar Tomar, Saswati Chakraborty
The impact of air flow rate on aerobic granulation was evaluated for treating toxic multiple pollutants; phenol (400 mg L-1 ), thiocyanate (100 mg L-1 ) and ammonia nitrogen (100 mg L-1 ) by using three lab scale sequencing batch reactors (SBRs) (R1, R2 and R3). Larger granules (2938.67 ± 64.91 μm) with higher biomass concentration (volatile solids of 4.17 ± 0.09 g L-1 ), higher granule settling velocity (55.56 ± 1.36 m h-1 ) and lower sludge volume index (35.25 ± 1...
May 5, 2018: Journal of Environmental Management
Cristina Vieites-Blanco, Serafín J González-Prieto
The effects of alien plants on whole nutrient cycles have been scarcely studied, despite the increasing evidence on their impact on nutrient pools and fluxes. Carpobrotus edulis, a dangerous invasive plant in coastal areas worldwide, is considered an ecosystems engineer which, by changing many soil properties, benefits its own invasion and hampers the restoration of the invaded habitats. To study, for the first time, the 'true' impact of C. edulis on the soil N cycle, we used a paired 15 N labelling experiment and a Ntrace compartment model to estimate the gross N fluxes in the 0-5cm and 5-10cm soil layers of non-invaded and C...
April 1, 2018: Science of the Total Environment
Lili He, Yucui Bi, Jin Zhao, Cameron M Pittelkow, Xu Zhao, Shenqiang Wang, Guangxi Xing
Long-term studies that advance our mechanistic understanding of biochar (BC)‑nitrogen (N) interactions in agricultural soils are lacking. In this study, soil potential nitrification rates (PNR), the abundance and composition of ammonia-oxidizing archaea (AOA) and ammonia-oxidizing bacteria (AOB) communities following 4-year of BC application were investigated using the shaken-slurry procedure and molecular sequencing techniques for an acidic Oxisol (QU) and an alkaline Cambisol (YU). Soils were obtained from an outdoor soil column experiment with straw-BC application rates of 0 (BC0), 2...
April 1, 2018: Science of the Total Environment
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