scholarly journals Sediments nitrogen cycling influenced by submerged macrophytes growing in winter

2021 ◽  
Vol 83 (7) ◽  
pp. 1728-1738
Author(s):  
Zhang Dan ◽  
Wang Chuan ◽  
Zhou Qiaohong ◽  
Yuan Xingzhong
Keyword(s):  
Nitrogen Cycling ◽  
Submerged Macrophytes ◽  
Inorganic Nitrogen ◽  
Growth Period ◽  
Denitrification Rate ◽  
Nitrification Rate ◽  
Potamogeton Crispus ◽  
Eutrophic Lakes ◽  
Complementary Role ◽  
Chemical Conditions

Abstract Restoration of submerged macrophytes is one of the important measures for ecological treatment of eutrophic lakes. The changes in physical and chemical conditions caused by submerged macrophytes also affect the process of benthic nitrogen cycling. The growth period of Potamogeton crispus is mainly in winter. In order to understand the effect of submerged macrophytes growing in winter on nitrification rate and denitrification rate in the process of nitrogen cycling, experiments were carried out from winter to summer with vegetated and non-vegetated treatments. The results showed that the effect of submerged macrophytes on water temperature was not significant in winter. The nitrogen cycling was mainly affected by variables, which were inorganic nitrogen and dissolved oxygen. Submerged macrophytes had little effect on nitrification rate, but had a certain inhibition on denitrification rate by providing oxygen from photosynthesis. In total, submerged macrophytes growing in winter have little effect on nitrogen cycling in sediment. However, submerged macrophytes growing in winter can increase the attachment surface of microbes and inhibit resuspension of sediment, which play a complementary role to submerged macrophytes growing in summer for maintaining stability of eutrophic lakes.

scholarly journals Changes of Soil Microbes Related with Carbon and Nitrogen Cycling after Long-Term CO2 Enrichment in a Typical Chinese Maize Field

2020 ◽  
Vol 12 (3) ◽  
pp. 1250 ◽  
Author(s):  
Tiantian Diao ◽  
Zhengping Peng ◽  
Xiaoguang Niu ◽  
Rongquan Yang ◽  
Fen Ma ◽  
...  
Keyword(s):  
16S Rrna ◽  
Nitrogen Cycling ◽  
Relative Abundance ◽  
Soil Microbes ◽  
Inorganic Nitrogen ◽  
Ammonia Oxidizing Bacteria ◽  
Rhizospheric Soil ◽  
Carbon And Nitrogen ◽  
Carbon And Nitrogen Cycling ◽  
Maize Field

Elevated atmospheric CO2 concentration (eCO2) has been the most important driving factor and characteristic of climate change. To clarify the effects of eCO2 on the soil microbes and on the concurrent status of soil carbon and nitrogen, an experiment was conducted in a typical summer maize field based on a 10-year mini FACE (Free Air Carbon Dioxide Enrichment) system in North China. Both rhizospheric and bulk soils were collected for measurement. The soil microbial carbon (MBC), nitrogen (MBN), and soil mineral N were measured at two stages. Characteristics of microbes were assayed for both rhizospheric soil and bulk soils at the key stage. We examined the plasmid copy numbers, diversities, and community structures of bacteria (in terms of 16s rRNA), fungi (in terms of ITS-internal transcribed spacer), ammonia oxidizing bacteria (AOB) and denitrifiers including nirK, nirS, and nosZ using the Miseq sequencing technique. Results showed that under eCO2 conditions, both MBC and MBN in rhizospheric soil were increased significantly. The quantity of ITS was increased in the eCO2 treatment compared with that in the ambient CO2 (aCO2) treatment, while the quantity of 16s rRNA in rhizospheric soil showed decrease in the rhizospheric soil in the eCO2 treatment. ECO2 changed the relative abundance of microbes in terms of compositional proportion of some orders or genera particularly in the rhizospheric soil-n particular, Chaetomium increased for ITS, Subgroups 4 and 6 increased for 16s rRNA, Nitrosospira decreased for AOB, and some genera showed increase for nirS, nirK, and nosZ. Nitrate N was the main inorganic nitrogen form at the tasseling stage and both quantities of AOB and denitrifiers, as well as the nosZ/(nirS+nirK) showed an increase under eCO2 conditions particularly in the rhizospheric soil. The Nitrosospira decreased in abundance under eCO2 conditions in the rhizospheric soil and some genera of denitrifiers also showed differences in abundance. ECO2 did not change the diversities of microbes significantly. In general, results suggested that 10 years of eCO2 did affect the active component of C and N pools (such as MBC and MBN) and both the quantities and relative abundance of microbes which are involved in carbon and nitrogen cycling, possibly due to the differences in both the quantities and component of substrate for relevant microbes in the rhizospheric soils.

Effects of aquatic macrophytes on physico-chemical conditions of three contrasting lowland streams: a consequence of diffuse pollution from agriculture?

2001 ◽  
Vol 43 (5) ◽  
pp. 163-168 ◽  
Author(s):  
R. J. Wilcock ◽  
J. W. Nagels
Keyword(s):  
Aquatic Macrophytes ◽  
Aquatic Vegetation ◽  
Submerged Macrophytes ◽  
Third Stream ◽  
Lowland Streams ◽  
Riparian Plants ◽  
Agricultural Catchments ◽  
Physico Chemical ◽  
Photosynthetic Production ◽  
Chemical Conditions

Three lowland streams in developed pasture catchments with different farming intensities exhibited contrasting summer diurnal variations in pH, DO and temperature. These are ascribed to differences in dominant aquatic vegetation and their respective effects on shade, and on photosynthetic production and respiration within each stream. The stream dominated by submerged macrophytes had the greatest amplitude swings in DO and pH, and DO levels of 86–128% saturation. Floating marginal macrophytes reduced photosynthetic inputs while providing additional organic loading for respiration, with consequent flat DO and pH curves and conditions not conducive to healthy stream ecosystems. The third stream was shaded by riparian plants, which inhibited photosynthetic effects on DO and pH so that diurnal variation was intermediate between the other two streams. The interaction between nutrients and increased insolation in agricultural catchments, in stimulating aquatic plants, needs to be better understood for managing the sustainability of stream habitats and ecosystems.

Intercropping affects genetic potential for inorganic nitrogen cycling by root-associated microorganisms in Medicago sativa and Dactylis glomerata

2017 ◽  
Vol 119 ◽  
pp. 260-266 ◽  
Author(s):  
Ming Zhao ◽  
Christopher M. Jones ◽  
Johan Meijer ◽  
Per-Olof Lundquist ◽  
Petra Fransson ◽  
...  
Keyword(s):  
Medicago Sativa ◽  
Nitrogen Cycling ◽  
Inorganic Nitrogen ◽  
Dactylis Glomerata ◽  
Genetic Potential

PRELIMINARY STUDIES ON THE UTILIZATION AND RELEASE OF AMINO ACIDS BY CYLINDROCARPON RADICICOLA WOLL.

1961 ◽  
Vol 39 (6) ◽  
pp. 1531-1536 ◽  
Author(s):  
R. G. Atkinson
Keyword(s):  
Amino Acids ◽  
Inorganic Nitrogen ◽  
Growth Period ◽  
Amino Acid Uptake ◽  
Sole Source ◽  
Acid Uptake ◽  
Shake Culture ◽  
One Dimensional ◽  
High Level ◽  
Basal Salts

One-dimensional paper chromatographic studies demonstrated that, in the absence of inorganic nitrogen, shake cultures of Cylindrocarpon radicicola Woll. preferentially utilized glutamic acid, proline, phenylalanine, and leucine from a basal salts – dextrose medium containing also histidine, aspartic acid, threonine, and valine. A similar analysis of slower-growing stationary cultures in the same medium failed to reveal this pattern of amino acid uptake. The growth of C. radicicola in a basal salts – dextrose medium containing KNO3 as the sole source of nitrogen resulted in the appearance of numerous amino acids in both stationary and shake culture fluids. The release of amino acids in stationary culture increased from a low to a high level after a growth period of 7 and 14 days, respectively. In shake culture, however, the opposite trend occurred.

Role of chemical and physical variables in regulating microcystin-LR concentration in phytoplankton of eutrophic lakes

2000 ◽  
Vol 57 (8) ◽  
pp. 1584-1593 ◽  
Author(s):  
Brian G Kotak ◽  
Angeline K-Y Lam ◽  
Ellie E Prepas ◽  
Steve E Hrudey
Keyword(s):  
Environmental Factors ◽  
Microcystis Aeruginosa ◽  
Total Phosphorus ◽  
Inorganic Nitrogen ◽  
Eutrophic Lakes ◽  
Cyanobacterial Toxin ◽  
Phytoplankton Communities ◽  
Physical Variables ◽  
Main Producer

A survey of eutrophic to hypereutrophic hardwater lakes in central Alberta was conducted to test the hypotheses that the concentration of the cyanobacterial toxin microcystin-LR (MC-LR) in phytoplankton is regulated by environmental factors that affect both the biomass of the main producer of the toxin, Microcystis aeruginosa, and the concentration of the toxin in the cells. Of all environmental factors examined, total phosphorus was the strongest correlate of both M. aeruginosa biomass and cellular MC-LR (expressed as micrograms per gram of M. aeruginosa). Microcystis aeruginosa biomass was also strongly negatively related to the total nitrogen to total phosphorus ratio (TN:TP) and inorganic nitrogen (NO2- + NO3-, NH4+). A univariate regression model of TN:TP explained the most variation in MC-LR concentration (expressed as nanograms of cellular toxin per litre) in mixed phytoplankton communities. This study indicated that MC-LR dynamics in phytoplankton of lakes was related to changes in the concentration and ratio of phosphorus and nitrogen.

scholarly journals Photoproduction of ammonium in the Southeastern Beaufort Sea and its biogeochemical implications

2012 ◽  
Vol 9 (4) ◽  
pp. 4441-4482 ◽  
Author(s):  
H. Xie ◽  
S. Bélanger ◽  
G. Song ◽  
R. Benner ◽  
A. Taalba ◽  
...  
Keyword(s):  
Nitrogen Cycling ◽  
Dissolved Organic Nitrogen ◽  
Organic Nitrogen ◽  
Inorganic Nitrogen ◽  
River Estuary ◽  
Beaufort Sea ◽  
Canada Basin ◽  
Molar Ratio ◽  
Entire Study ◽  
Mackenzie River

Abstract. Photochemistry of dissolved organic matter (DOM) plays an important role in marine biogeochemical cycles, including the regeneration of inorganic nutrients. DOM photochemistry affects nitrogen cycling by converting bio-refractory dissolved organic nitrogen to labile inorganic nitrogen, mainly ammonium (NH4+). During the August 2009 Mackenzie Light and Carbon (MALINA) Program, the absorbed photon-based efficiency spectra of NH4+ photoproduction (i.e. photoammonification) were determined using water samples from the SE Beaufort Sea, including the Mackenzie River estuary, shelf, and Canada Basin. The photoammonification efficiency decreased with increasing wavelength across the ultraviolet and visible regimes and was higher in offshore waters than in shelf and estuarine waters. The efficiency was positively correlated with the molar nitrogen : carbon ratio of DOM and negatively correlated with the absorption coefficient of chromophoric DOM (CDOM). Combined with collateral measurements of CO2 and CO photoproduction, this study revealed a stoichiometry of DOM photochemistry with a CO2:CO:NH4+ molar ratio of 165:11:1 in the estuary, 60:3:1 on the shelf, and 18:2:1 in the Canada Basin. The NH4+ efficiency spectra, along with solar photon fluxes, CDOM absorption coefficients and sea ice concentrations, were used to model the monthly surface and depth-integrated photoammonification rates in 2009. The summertime (June–August) rates at the surface reached 6.6 nmol l−1 d−1 on the Mackenzie Shelf and 3.7 nmol l−1 d−1 further offshore; the depth-integrated rates were correspondingly 8.8 μmol m−2 d−1 and 11.3 μmol m−2 d−1. The offshore depth-integrated rate in August (8.0 μmol m−2 d−1) was comparable to the missing dissolved inorganic nitrogen (DIN) source required to support the observed primary production in the upper 10-m layer of that area. The yearly NH4+ photoproduction in the entire study area was estimated to be 1.4 × 108 moles, with 85 % of it being generated in summer when riverine DIN input is low. Photoammonification could mineralize 4 % of the annual dissolved organic nitrogen (DON) exported from the Mackenzie River and provide a~DIN source corresponding to 7 % of the riverine DIN discharge and 1400 times the riverine NH4+ flux. Under a climate warming-induced ice-free scenario, these quantities would increase correspondingly to 6 %, 11 %, and 2100 times. Photoammonification is thus a significant nitrogen cycling term and may fuel previously unrecognized autotrophic and heterotrophic production pathways in the surface SE Beaufort Sea.

scholarly journals Seasonality and Species Specificity of Submerged Macrophyte Biomass in Shallow Lakes Under the Influence of Climate Warming and Eutrophication

2021 ◽  
Vol 12 ◽  
Author(s):  
Haoping Wu ◽  
Beibei Hao ◽  
Hyunbin Jo ◽  
Yanpeng Cai
Keyword(s):  
Climate Warming ◽  
Shallow Lakes ◽  
Nutrient Enrichment ◽  
Plant Biomass ◽  
Submerged Macrophytes ◽  
Anthropogenic Activities ◽  
Species Specificity ◽  
Growth Responses ◽  
Potamogeton Crispus ◽  
Explanatory Factors

Climate warming and eutrophication caused by anthropogenic activities strongly affect aquatic ecosystems. Submerged macrophytes usually play a key role in shallow lakes and can maintain a stable clear state. It is extremely important to study the effects of climate warming and eutrophication on the growth of submerged macrophytes in shallow lakes. However, the responses of submerged macrophytes to climate warming and eutrophication are still controversial. Additionally, the understanding of the main pathways impacting submerged macrophytes remains to be clarified. In addition, the influence of seasonality on the growth responses of submerged macrophytes to climate warming and eutrophication requires further elucidation. In this study, we conducted a series of mesocosm experiments with four replicates across four seasons to study the effects of rising temperature and nutrient enrichment on the biomass of two submerged macrophytes, Potamogeton crispus and Elodea canadensis. Our results demonstrated the seasonality and species specificity of plant biomass under the influence of climate warming and eutrophication, as well as the main explanatory factors in each season. Consistent with the seasonal results, the overall results showed that E. canadensis biomass was directly increased by rising temperature rather than by nutrient enrichment. Conversely, the overall results showed that P. crispus biomass was indirectly reduced by phosphorus enrichment via the strengthening of competition among primary producers. Distinct physiological and morphological traits may induce species-specific responses of submerged macrophytes to climate warming and eutrophication, indicating that further research should take interspecies differences into account.

scholarly journals Microbial nitrogen cycling on the Greenland Ice Sheet

2011 ◽  
Vol 8 (5) ◽  
pp. 10423-10457 ◽  
Author(s):  
J. Telling ◽  
M. Stibal ◽  
A. M. Anesio ◽  
M. Tranter ◽  
I. Nias ◽  
...  
Keyword(s):  
Nitrogen Fixation ◽  
Nitrogen Cycling ◽  
Microbial Growth ◽  
Inorganic Nitrogen ◽  
Ice Sheet ◽  
Greenland Ice Sheet ◽  
Available Nitrogen ◽  
Microbial Nitrogen ◽  
Nitrogen Demand

Abstract. Microbial nitrogen cycling was investigated along a 79 km transect into the Greenland Ice Sheet (GrIS) in early August 2010. The depletion of dissolved nitrate and production of ammonium (relative to icemelt) in cryoconite holes within 7.5 km of the ice sheet margin suggested microbial uptake and ammonification respectively. Nitrogen fixation (<4.2 μmoles C2H4 m−2 day−1 to 16.3 μmoles C2H4 m−2 day−1) was active in some cryoconite holes at sites up to 5.7 km from the ice sheet margin, with nitrogen fixation inversely correlated to concentrations of inorganic nitrogen. There may be the potential for the zone of nitrogen fixation to progressively extend further into the interior of the GrIS as the melt season progresses as reserves of available nitrogen are depleted. Estimated annual inputs of nitrogen from nitrogen fixation along the transect were at least two orders of magnitude lower than inputs from precipitation, with the exception of a 100 m long marginal debris-rich zone where nitrogen fixation could potentially equal or exceed that of precipitation. The average estimated contribution of nitrogen fixation to the nitrogen demand of net microbial growth at sites along the transect ranged from 0% to 17.5%.

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