scholarly journals Long-Term Water Quality Changes as a Result of a Sustainable Restoration—A Case Study of Dimictic Lake Durowskie

Water ◽  
2019 ◽  
Vol 11 (3) ◽  
pp. 616 ◽  
Author(s):  
Renata Dondajewska ◽  
Katarzyna Kowalczewska-Madura ◽  
Ryszard Gołdyn ◽  
Anna Kozak ◽  
Beata Messyasz ◽  
...  
Keyword(s):  
Lake Restoration ◽  
External Loading ◽  
Nitrogen Transformations ◽  
External Interference ◽  
Fresh Organic Matter ◽  
Ammonium N ◽  
Ecosystem Reconstruction ◽  
Oxygen Conditions ◽  
Urban Flow

Nature-based solutions in lake restoration enable gradual ecosystem reconstruction without drastic and expensive intervention. Sustainable lake restoration involves limited external interference strong enough to initiate and maintain positive changes in the ecosystem. It was introduced in Lake Durowskie, an urban, flow-through lake situated in Western Poland, using hypolimnetic aeration, phosphorus precipitation with small doses of chemicals and biomanipulation in 2009, and is continued until today. Oxygen conditions in the lake hypolimnion after initial deterioration were gradually improved, and finally a shortening of the duration and range of oxygen deficits was observed. Nitrogen transformations were induced in the hypolimnion by water aeration as well, reducing ammonium N (30% during 2013–2017 in comparison to 2008) and increasing nitrates (90% in 2013–2017 in comparison to 2008). Phosphorus content was diminished (19% during 2015–2017 in relation to 2008 for SRP) due to effective iron-binding and a smaller amount of fresh organic matter being decomposed. Its reduction was related to lower phytoplankton biomass, expressed in a decrease of chlorophyll-a concentrations (55% reduction during 2013–2017 in comparison to 2008) and an increase in water transparency (two-fold during 2013–2017 in relation to 2008) throughout the nine years of treatment. A long-term restoration program, based on non-aggressive, multiple in-lake techniques was applied and, despite the lack of a reduction in total external loading, was able to suppress progressive eutrophication.

scholarly journals Prolonged exposure to low oxygen improves hypoxia tolerance in a freshwater fish

2019 ◽  
Vol 7 (1) ◽  
Author(s):  
Kayla L Gilmore ◽  
Zoe A Doubleday ◽  
Bronwyn M Gillanders
Keyword(s):  
Freshwater Fish ◽  
Prolonged Exposure ◽  
Hypoxia Tolerance ◽  
Low Oxygen ◽  
Oxygen Conditions

Lay summary It is poorly understood whether fish can acclimate to prolonged low-oxygen conditions (or hypoxia). Our study shows that prior long-term exposure to low-oxygen conditions improves tolerance to low-oxygen in a freshwater fish. The results of our study aid our understanding of long-term responses of freshwater fish to low-oxygen to hypoxic events.

Interactions between liming and availability of C and P regulate nitrogen transformations and denitrifying potential in an acidic arable soil

2020 ◽  
Author(s):  
Zhi Liang ◽  
Diego Abalos ◽  
Lars Elsgaard
Keyword(s):  
Soil Ph ◽  
Crop Yields ◽  
Arable Soil ◽  
P Availability ◽  
Agricultural Practice ◽  
Management Option ◽  
Nitrogen Transformations ◽  
P Addition ◽  
Limed Soil

<p>Liming to increase pH of acidic soils is a common agricultural practice to optimize crop yields, which also modulates greenhouse gas emissions from soils. In particular, soil pH has been identified as a primary regulator of denitrification pathways with enhanced ratio of nitrous oxide (N<sub>2</sub>O) to dinitrogen (N<sub>2</sub>) emissions (i.e., enhanced N<sub>2</sub>O/N<sub>2</sub> ratio) at lower soil pH. Therefore liming could represent a potential management option to mitigate soil N<sub>2</sub>O emissions. However, changes in soil pH have pervasive effects on general microbial activity and on soil properties, including transformations of carbon (C) and bioavailability of phosphorus (P), with a feedback on microbial processes. Thus, the eventual net effects of liming on microbially derived N<sub>2</sub>O emissions may be complex. The aim of this study was to discern the interaction between liming (soil pH), and availability of C and P in regulating N<sub>2</sub>O emissions from acidic fertilized agroecosystems. Using coarse sandy soils from a long-term liming field experiment, N<sub>2</sub>O/N<sub>2</sub> ratios from denitrifying enzyme activity was shown to be strongly affected by liming, i.e., with gradually decreasing ratios at increasing soil pH. Although liming acidic soil (pH, 3.6) to almost neutral (pH, 6.4) favored the reduction of N<sub>2</sub>O to N<sub>2</sub>, it also enhanced the overall denitrification rate, which eventually resulted in the highest N<sub>2</sub>O emission from moderately limed treatments (pH, 4.7). Interactions between P availability and denitrification (and N<sub>2</sub>O emission) occurred, where P addition generally increased cumulative N<sub>2</sub>O emissions with strongest effect at the moderately limed soil. Mechanistic hypotheses for this effect are discussed. Overall, our results suggest that a critical liming rate should be pursued which may lead to substantial mitigation of N<sub>2</sub>O emissions from acidic arable soil.</p>

scholarly journals Retention and Internal Loading of Phosphorus in Shallow, Eutrophic Lakes

2001 ◽  
Vol 1 ◽  
pp. 427-442 ◽  
Author(s):  
Martin Sondergaard ◽  
Peder Jens Jensen ◽  
Erik Jeppesen
Keyword(s):  
Water Quality ◽  
Lake Water ◽  
Recovery Period ◽  
Internal Loading ◽  
External Loading ◽  
Lake Water Quality ◽  
Eutrophic Lakes ◽  
P Release ◽  
P Accumulation

This paper gives a general overview of the nature and important mechanisms behind internal loading of phosphorus (P), which is a phenomenon appearing frequently in shallow, eutrophic lakes upon a reduction of the external loading. Lake water quality is therefore not improved as expected. In particular summer concentrations rise and P retention may be negative during most of the summer. The P release originates from a pool accumulated in the sediment when the external loading was high. In most lake sediments, P bound to redox-sensitive iron compounds or P fixed in more or less labile organic forms constitute major fractions forms that are potentially mobile and eventually may be released to the lake water. The duration of the recovery period following P loading reduction depends on the loading history, but it may last for decades in lakes with a high sediment P accumulation. During the phase of recovery, both the duration and net P release rates from the sediment seem to decline progressively. Internal P loading is highly influenced by the biological structure as illustrated by lakes shifting from the turbid to the clearwater state as a result of, for example, biomanipulation. In these lakes P concentrations may be reduced to 50% of the pre-biomanipulation level and the period with negative retention during summer can thus be reduced considerably. The duration of internal loading can be reduced significantly by different restoration methods such as dredging to remove accumulated P or addition of iron or alum to elevate the sorption capacity of sediments. However, an important prerequisite for achieving long-term benefits to water quality is a sufficient reduction of the external P loading.

CHANGES IN NATURAL 15N ABUNDANCE ASSOCIATED WITH PEDOGENIC PROCESSES IN SOIL. II. CHANGES ON DIFFERENT SLOPE POSITIONS

1980 ◽  
Vol 60 (2) ◽  
pp. 365-372 ◽  
Author(s):  
R. E. KARAMANOS ◽  
D. A. RENNIE
Keyword(s):  
Total Nitrogen ◽  
Organic N ◽  
Total N ◽  
Nitrate N ◽  
Ammonium N ◽  
Soil Forming Processes ◽  
Pedogenic Processes ◽  
15N Abundance ◽  
Upper Slope

Rather marked variations in δa15N values were obtained in a study carried out on samples taken from four soils belonging to the Weyburn soil association. The δa15N of the total N of well-drained depressional profiles dropped sharply with depth and, in contrast, for upper slope positions was relatively constant to a depth of approximately 5 m. This characteristic enrichment in the heavier isotope of total nitrogen of surface horizons may represent long-term immobilization of partially oxidized ammonium N into the organic N fraction; δa15N of the total N more closely represents past soil-forming processes while that of the nitrate N appears to reflect, in addition, recent N cycle stresses.

Lake Restoration by Fish Removal: Short- and Long-Term Effects in 36 Danish Lakes

Ecosystems ◽  
2008 ◽  
Vol 11 (8) ◽  
pp. 1291-1305 ◽  
Author(s):  
Martin Søndergaard ◽  
Lone Liboriussen ◽  
Asger R. Pedersen ◽  
Erik Jeppesen
Keyword(s):  
Lake Restoration ◽  
Long Term Effects ◽  
Fish Removal ◽  
Short And Long Term

Viscoelastic Properties of Semi-Crystalline Thermoplastic Polymers: Dynamic Analysis and Creep

2012 ◽  
Vol 188 ◽  
pp. 211-218 ◽  
Author(s):  
Dan Andrei Serban ◽  
Henry Hanson ◽  
Liviu Marşavina ◽  
Vadim V. Silberschmidt
Keyword(s):  
Viscoelastic Properties ◽  
Polymeric Materials ◽  
Mechanical Analysis ◽  
External Loading ◽  
Thermoplastic Polymer ◽  
Elastic Solids ◽  
Short Term ◽  
Creep Tests ◽  
And Storage

When subjected to external loading, polymeric materials behave in a manner intermediate between elastic solids and viscous fluids. Their mechanical properties depend on a material’s viscous flow, which, in turn, is influenced by (i) temperature, with its different magnitudes determining a ductile or brittle behaviour and (ii) time, through the effect of a deformation rate and long-term relaxation. Short-term viscoelastic properties (loss and storage moduli) of a studied semi-crystalline thermoplastic polymer were obtained using Dynamic Mechanical Analysis, while its long-term viscoelastic properties (compliances) were determined using creep tests.

scholarly journals Colimitation of decomposition by substrate and decomposers – a comparison of model formulations

2008 ◽  
Vol 5 (1) ◽  
pp. 163-190 ◽  
Author(s):  
T. Wutzler ◽  
M. Reichstein
Keyword(s):  
Organic Matter ◽  
Steady State ◽  
Soil Organic Matter ◽  
Priming Effect ◽  
Deep Soil ◽  
Fresh Organic Matter ◽  
Decomposition Models ◽  
Decomposer Community ◽  
Som Decomposition

Abstract. Decomposition of soil organic matter (SOM) is limited by both the available substrate and the active decomposer community. The understanding of this colimitation strongly affects the understanding of feedbacks of soil carbon to global warming and its consequences. This study compares different formulations of soil organic matter (SOM) decomposition. We compiled formulations from literature into groups according to the representation of decomposer biomass on the SOM decomposition rate a) non-explicit (substrate only), b) linear, and c) non-linear. By varying the SOM decomposition equation in a basic simplified decomposition model, we analyzed the following questions. Is the priming effect represented? Under which conditions is SOM accumulation limited? And, how does steady state SOM stocks scale with amount of fresh organic matter (FOM) litter inputs? While formulations (a) did not represent the priming effect, with formulations (b) steady state SOM stocks were independent of amount of litter input. Further, with several formulations (c) there was an offset of SOM that was not decomposed when no fresh OM was supplied. The finding that a part of the SOM is not decomposed on exhaust of FOM supply supports the hypothesis of carbon stabilization in deep soil by the absence of energy-rich fresh organic matter. Different representations of colimitation of decomposition by substrate and decomposers in SOM decomposition models resulted in qualitatively different long-term behaviour. A collaborative effort by modellers and experimentalists is required to identify appropriate and inappropriate formulations.

scholarly journals Changes in forms of available nitrogen and respiration in soil of beech forest as a reaction to a deforestation resulting from wind storm

2013 ◽  
Vol 61 (1) ◽  
pp. 107-113 ◽  
Author(s):  
Aleš Kučera ◽  
Ladislav Holík ◽  
Karel Marosz ◽  
Antonín Martiník ◽  
Dušan Vavříček
Keyword(s):  
Beech Forest ◽  
Nitrate Content ◽  
Available Nitrogen ◽  
Respiration Activity ◽  
Ammonium N ◽  
Significant Difference ◽  
The One ◽  
Long Term Observation ◽  
A Site

The article deals with the reaction of soil environment to a violent deforestation resulting from a wind storm. As a material, permanent inventory plot located in Training Forest Enterprise Masaryk Forest Křtiny was selected. The plot represents beech high forest, where soil was sampled from four types of sample plots: (1) maternal forest representing situation before the storm; (2) zone of transition from the maternal forest to the open area; (3) reafforested clearing; (4) natural evolution. From each sample plot type, 6 mixed samples of Ah horizon were analysed to assess N-ammonium (N-NH4+) and N-nitrates (NO3−) content and respiration activity. The results show a significant difference between the respiration activities of the particular sample plots, as well as a significant difference in the content of N-ammonium and N-nitrate forms, the maternal forest representing a site of the lowest biological (and respiration) activity on the one hand, and, on the other hand, site of high N-ammonium and low N-nitrate content, respectively. From the results, intensive nitrification caused by the deforestation is evident. The results are to be used as a starting level for a long-term observation of reaction of the forest beech ecosystem to deforestation and selected types of forest management.

scholarly journals Ion Selective Amperometric Biosensors for Environmental Analysis of Nitrate, Nitrite and Sulfate

Sensors ◽  
2020 ◽  
Vol 20 (15) ◽  
pp. 4326
Author(s):  
Niels Peter Revsbech ◽  
Michael Nielsen ◽  
Deby Fapyane
Keyword(s):  
Inorganic Ions ◽  
Natural Environments ◽  
Nitrogen Transformations ◽  
Redox Transformation ◽  
Whole Cells ◽  
Long Term Stability ◽  
High Degree ◽  
Insight Into ◽  
A Current

Inorganic ions that can be redox-transformed by living cells can be sensed by biosensors, where the redox transformation gives rise to a current in a measuring circuit. Such biosensors may be based on enzymes, or they may be based on application of whole cells. In this review focus will be on biosensors for the environmentally important ions NO3−, NO2−, and SO42−, and for comparison alternative sensor-based detection will also be mentioned. The developed biosensors are generally characterized by a high degree of specificity, but unfortunately also by relatively short lifetimes. There are several investigations where biosensor measurement of NO3− and NO2− have given new insight into the functioning of nitrogen transformations in man-made and natural environments such as sediments and biofilms, but the biosensors have not become routine tools. Future modifications resulting in better long-term stability may enable such general use.

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