Dataset Information

Laboratory study on nitrate removal and nitrous oxide emission in intact soil columns collected from nitrogenous loaded riparian wetland, Northeast China.

ABSTRACT: Nitrate [Formula: see text] pollution of surface and groundwater systems is a major problem globally. For some time now wetlands have been considered potential systems for improving water quality. Nitrate dissolved in water moving through wetlands can be removed through different processes, such as the denitrification process, where heterotrophic facultative anaerobic bacteria use [Formula: see text] for respiration, leading to the production of nitrogen (N2) and nitrous oxide (N2O) gases. Nitrate removal and emission of N2O in wetlands can vary spatially, depending on factors such as vegetation, hydrology and soil structure. This study intended to provide a better understanding of the spatial variability and processes involved in [Formula: see text] removal and emission of N2O in riparian wetland soils. We designed a laboratory experiment simulating surface water flow through soil columns collected from different sites dominated by different plant species within a wetland. Water and gas samples for [Formula: see text] and N2O analyses were collected every 5 days for a period of 30 days. The results revealed significant removal of [Formula: see text] in all the soil columns, supporting the role of riparian wetland soils in removing nitrogen from surface runoff. Nitrate removal at 0 and 10cm depths in sites dominated by Phragmites australis and Carex schnimdtii was significantly higher than in the site dominated by Calamagrostis epigeio. Nitrous oxide emissions varied spatially and temporally with negative flux observed in sites dominated by P. australis and C. schnimdtii. These results reveal that in addition to the ability of wetlands to remove [Formula: see text], some sites within wetlands are also capable of consuming N2O, hence mitigating not only agricultural nitrate pollution but also climate change.

SUBMITTER: Mwagona PC

PROVIDER: S-EPMC6438505 | biostudies-literature | 2019

REPOSITORIES: biostudies-literature

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Laboratory study on nitrate removal and nitrous oxide emission in intact soil columns collected from nitrogenous loaded riparian wetland, Northeast China.

Mwagona Patteson Chula PC Yao Yunlong Y Yuanqi Shan S Yu Hongxian H

PloS one 20190328 3

Nitrate [Formula: see text] pollution of surface and groundwater systems is a major problem globally. For some time now wetlands have been considered potential systems for improving water quality. Nitrate dissolved in water moving through wetlands can be removed through different processes, such as the denitrification process, where heterotrophic facultative anaerobic bacteria use [Formula: see text] for respiration, leading to the production of nitrogen (N2) and nitrous oxide (N2O) gases. Nitra ...[more]

PMID: 30921385

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Project description:Firmicutes have the capacity to remove excess nitrate from the environment via either denitrification, dissimilatory nitrate reduction to ammonium or both. The recent renewed interest in their nitrogen metabolism has revealed many interesting features, the most striking being their wide variety of dissimilatory nitrate reduction pathways. In the present study, nitrous oxide production from Bacillus licheniformis, a ubiquitous Gram-positive, spore-forming species with many industrial applications, is investigated.B. licheniformis has long been considered a denitrifier but physiological experiments on three different strains demonstrated that nitrous oxide is not produced from nitrate in stoichiometric amounts, rather ammonium is the most important end-product, produced during fermentation. Significant strain dependency in end-product ratios, attributed to nitrite and ammonium, and medium dependency in nitrous oxide production were also observed. Genome analyses confirmed the lack of a nitrite reductase to nitric oxide, the key enzyme of denitrification. Based on the gene inventory and building on knowledge from other non-denitrifying nitrous oxide emitters, hypothetical pathways for nitrous oxide production, involving NarG, NirB, qNor and Hmp, are proposed. In addition, all publically available genomes of B. licheniformis demonstrated similar gene inventories, with specific duplications of the nar operon, narK and hmp genes as well as NarG phylogeny supporting the evolutionary separation of previously described distinct BALI1 and BALI2 lineages.Using physiological and genomic data we have demonstrated that the common soil bacterium B. licheniformis does not denitrify but is capable of fermentative dissimilatory nitrate/nitrite reduction to ammonium (DNRA) with concomitant production of N2O. Considering its ubiquitous nature and non-fastidious growth in the lab, B. licheniformis is a suitable candidate for further exploration of the actual mechanism of N2O production in DNRA bacteria and its relevance in situ.

Project description:Misoprostol is listed in the WHO essential medicines list and can be used for induction of labour, for prevention and treatment of post-partum haemorrhage, and for abortions. The compound is unstable, and substandard misoprostol preparations have been detected in low- and middle-income countries. We now investigated the stability of misoprostol tablets according to the international guidelines for stability testing of pharmaceutical products. Three brands (four batches) of misoprostol tablets were collected in Malawi and Rwanda: the originator product, a WHO-prequalified product, and a generic product without WHO prequalification. A further batch of the originator product was collected in Germany. To investigate the effect of damage to the primary packaging, additional blister strips of one sample were intentionally damaged with a needle and investigated in parallel. Samples were placed in stability chambers for six months at 40°C/75% relative humidity (RH) and at 25°C/60% RH. After 0, 1, 2, 3 and 6 months, misoprostol content was determined according to the International Pharmacopeia. At 40°C/75% RH, all samples showed a decline of misoprostol content, but four of the batches still remained within the pharmacopeial specifications, while one of the two batches of the generic product without WHO-prequalification showed a final content of 86.2% which is out of specifications. Damage to the primary packaging greatly decreased stability, resulting in a final content of only 48.2% of the declared misoprostol amount. At 25°C/60% RH all samples remained in specifications for six months, even the sample with the damaged blister. Dissolution of misoprostol remained in specifications of the pharmacopoeia for six months for all batches, except for the sample with damaged blisters stored at 40°C/75% RH. This study confirms that the stability of misoprostol tablets must be ensured by intact, good-quality primary packaging. Careful supplier qualification is required in the procurement process.

Dataset Information

Laboratory study on nitrate removal and nitrous oxide emission in intact soil columns collected from nitrogenous loaded riparian wetland, Northeast China.

Publications

Laboratory study on nitrate removal and nitrous oxide emission in intact soil columns collected from nitrogenous loaded riparian wetland, Northeast China.

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