Basic Productivity of Trevor Channel and Alberni Inlet from Chemical Measurements

1956 ◽  
Vol 13 (1) ◽  
pp. 7-20 ◽  
Author(s):  
Michael Waldichuk
Keyword(s):  
Deep Water ◽  
Chemical Properties ◽  
Late Summer ◽  
Oxygen Depletion ◽  
Oxygen Deficit ◽  
Barkley Sound ◽  
Annual Productivity ◽  
Chemical Measurements ◽  
Phosphate Surplus ◽  
Plankton Feeders

Chemical properties of the waters in Trevor Channel and Alberni Inlet during late summer have been applied for an estimate of basic productivity. Based on the assumptions that the deep water in the system is renewed once per year and that the observed conditions in September represent the state of the water just before renewal, the oxygen deficit and the phosphate surplus in the deep water have been used as a measure of the organisms decomposed during the year. Oxygen depletion gives 28 g/m2 of plankton per year as carbon; phosphate liberation gives 31 g/m2. From fishery statistics it was estimated that the herring in Barkley Sound consume about one-quarter of the available plankton and all plankton feeders consume about one-half of the total. This would increase the above figures of productivity to 56 g/m2 and 62 g/m2, respectively. These values are probably a minimum annual productivity inasmuch as basic assumptions may not be completely fulfilled. Regeneration of nutrients in the surface layer, and some renewal of deep water by mixing and circulation, probably occur throughout the year.

The life history, growth, and age structure of Nephelopsis obscura Verrill, 1872 (Hirudinoidea) in Alberta

1977 ◽  
Vol 55 (3) ◽  
pp. 620-627 ◽  
Author(s):  
Ronald W. Davies ◽  
Roger P. Everett
Keyword(s):  
Deep Water ◽  
Late Summer ◽  
Shore Zone ◽  
Cocoon Production ◽  
Summer Generation ◽  
Water Zone ◽  
Nephelopsis Obscura ◽  
Spring Generation ◽  
Two Generations ◽  
First Time

Two generations of Nephelopsis obscura were produced annually in the spring and in the late summer. The spring generation was the progeny of the heavier elements of the previous year's spring generation and of the late-summer generation produced 2 years previously. The late-summer generation was produced by parts of the previous year's spring and late-summer generations. Each generation produced young after either 12 and 15 months or 12 and 19 months although each individual bred once only. Unlike other species of leeches studied N. obscura showed no direct correlation between cocoon production and water temperature, the primary prerequisite being a weight of more than 150 mg. Seasonal movements from the deep-water zone to the shore zone in spring and vice versa in the fall were recorded for the first time. The movements to the deep-water zone were not synchronous throughout the population, the spring generation completing its movements before the other components of the population.

Vertical Transport of Oxygen into the Hypolimnion of Lakes

1987 ◽  
Vol 44 (4) ◽  
pp. 852-858 ◽  
Author(s):  
R. J. Cornett ◽  
F. H. Rigler
Keyword(s):  
Heat Budget ◽  
Eddy Diffusivity ◽  
Oxygen Depletion ◽  
Vertical Transport ◽  
Oxygen Deficit ◽  
Eddy Diffusivities ◽  
Oxygen Gradients ◽  
Hypolimnetic Oxygen ◽  
Depletion Rate ◽  
Flux Parameter

Rates of vertical transport of oxygen into the hypolimnion were calculated by multiplying the vertical eddy diffusivity coefficients, determined from the heat budget, by the measured gradients in oxygen concentration. In 12 lakes, transport ranged from 0 to 70 mg O2∙m−2∙d−1 and was insensitive to the depth defining the upper boundary of the hypolimnion. Oxygen was transported into the hypolimnion of lakes with a thinner hypolimnion and out of the hypolimnion of lakes with a thick hypolimnion. Transport averaged 4% of the measured total rate of hypolimnetic oxygen depletion and < 10% of the depletion rate in individual strata. Pooling these results with published estimates of oxygen gradients and eddy diffusivities suggests that in lakes with different trophic status (phosphorus levels 4–100 μg∙L−1) and size (areas from 0.4 to 70 km2), vertical oxygen transport accounts for less than 15% of the hypolimnetic oxygen deficit. Oxygen depletion models will gain relatively little precision by including a vertical transport flux parameter.

scholarly journals Deep-water inflow event increases sedimentary phosphorus release on a multi-year scale

2021 ◽  
Vol 18 (9) ◽  
pp. 2981-3004
Author(s):  
Astrid Hylén ◽  
Sebastiaan J. van de Velde ◽  
Mikhail Kononets ◽  
Mingyue Luo ◽  
Elin Almroth-Rosell ◽  
...  
Keyword(s):  
Organic Matter ◽  
Deep Water ◽  
Oxygen Depletion ◽  
Inorganic Phosphorus ◽  
Phosphorus Release ◽  
Water Inflow ◽  
Low Oxygen ◽  
In Situ Experiment ◽  
Inflow Event ◽  
The Baltic

Abstract. Phosphorus fertilisation (eutrophication) is expanding oxygen depletion in coastal systems worldwide. Under low-oxygen bottom water conditions, phosphorus release from the sediment is elevated, which further stimulates primary production. It is commonly assumed that re-oxygenation could break this “vicious cycle” by increasing the sedimentary phosphorus retention. Recently, a deep-water inflow into the Baltic Sea created a natural in situ experiment that allowed us to investigate if temporary re-oxygenation stimulates sedimentary retention of dissolved inorganic phosphorus (DIP). Surprisingly, during this 3-year study, we observed a transient but considerable increase, rather than a decrease, in the sediment efflux of DIP and other dissolved biogenic compounds. This suggested that the oxygenated inflow elevated the organic matter degradation in the sediment, likely due to an increase in organic matter supply to the deeper basins, potentially combined with a transient stimulation of the mineralisation efficiency. As a result, the net sedimentary DIP release per m2 was 56 %–112 % higher over the years following the re-oxygenation than before. In contrast to previous assumptions, our results show that inflows of oxygenated water to anoxic bottom waters can increase the sedimentary phosphorus release.

scholarly journals Distributions of surface water CO<sub>2</sub> and air-sea flux of CO<sub>2</sub> in coastal regions of the Canadian Beaufort Sea in late summer

2008 ◽  
Vol 5 (6) ◽  
pp. 5093-5132 ◽  
Author(s):  
A. Murata ◽  
K. Shimada ◽  
S. Nishino ◽  
M. Itoh
Keyword(s):  
Surface Water ◽  
Dissolved Inorganic Carbon ◽  
High Capacity ◽  
Coastal Region ◽  
Chemical Properties ◽  
Late Summer ◽  
Co2 Flux ◽  
Beaufort Sea ◽  
Atmospheric Co2 ◽  
Co2 Sink

Abstract. To quantify the air-sea flux of CO2 in a high-latitude coastal region, we conducted shipboard observations of atmospheric and surface water partial pressures of CO2 (pCO2) and total dissolved inorganic carbon (TCO2) in the Canadian Beaufort Sea (150° W–127° W; 69° N–73° N) in late summer 2000 and 2002. Surface water pCO2 was lower than atmospheric pCO2 (2000, 361.0 μatm; 2002, 364.7 μatm), and ranged from 250 to 344 μatm. Accordingly, ΔpCO2, which is the driving force of the air-sea exchange of CO2 and is calculated from differences in pCO2 between the sea surface and the overlying air, was generally negative (potential sink for atmospheric CO2), although positive ΔpCO2 values (source) were also found locally. Distributions of surface water pCO2, as well as those of ΔpCO2 and CO2 flux, were controlled mainly by water mixing related to river discharge. The air-sea fluxes of CO2 were −15.0 and −16.8 mmol m−2 d−1 on average in 2000 and 2002, respectively, implying that the area acted as a moderate sink for atmospheric CO2. The air-to-sea net CO2 flux in an extended area of the western Arctic Ocean (411 000 km2) during the ice-free season (=100 days) was calculated as 10.2±7.7 mmol m−2 d−1, equivalent to a regional CO2 sink of 5.0±3.8 Tg C. The estimated buffer factor was 1.5, indicating that the area is a high-capacity CO2 sink. These CO2 flux estimates will need to be revised because they probably include a bias due to the vertical gradients of physical and chemical properties characteristic in the region, which have not yet been adequately considered.

On the oxygen deficit in the Baltic deep water

Tellus ◽  
1970 ◽  
Vol 22 (3) ◽  
pp. 357-357 ◽  
Author(s):  
Gunnar Kullenberg
Keyword(s):  
Deep Water ◽  
Oxygen Deficit ◽  
The Baltic

Forty years record of the metalimnetic oxygen minimum in Germany’s largest drinking water reservoir

2021 ◽  
Author(s):  
Michael Seewald ◽  
Chenxi Mi ◽  
Jan Donner ◽  
Karsten Rinke
Keyword(s):  
Drinking Water ◽  
Water Quality Management ◽  
Water Reservoir ◽  
Oxygen Depletion ◽  
Oxygen Deficit ◽  
Drinking Water Reservoir ◽  
Lakes And Reservoirs ◽  
Low Levels ◽  
Oxygen Minimum

&lt;p&gt;Dissolved oxygen is a central player in water quality management of lakes and reservoirs. Low levels or absence of oxygen poses a major problem, especially in drinking water reservoirs. Usually, the focus lies on the oxygen depletion in deep water. However, in many stably stratified water bodies, significant oxygen deficits have been documented in the metalimnion, even in lakes of low trophic state. This phenomenon is known as metalimnetic oxygen minimum (MOM) and the causes of MOM have been discussed controversially. The Rappbode Dam, Germany's largest drinking water reservoir, forms a MOM every year and long-term observations indicate that the oxygen deficit may have increased in recent years. Although the data cover a long period (40 years), they are very heterogeneous in terms of temporal and spatial resolution. Our study aims at systematically analysing the available data to characterize the interannual development of the MOM with respect to existing trends and to identify relevant environmental and management factors. The results confirm increasing surfacewater temperatures and unchanged deepwater temperatures in summer (Mai to October) as well as an increasingly prolonged summer stratification in the course of global warming. In contrast to the previous working hypothesis, increasing stratification duration is not correlated with the significantly increasing (p 0.009; &amp;#964; -0.26) annual maximum intensity of the MOM.&lt;/p&gt;

scholarly journals Prediction of scaled feed intake in weaner pigs using physico-chemical properties of fibrous feeds

2013 ◽  
Vol 110 (4) ◽  
pp. 774-780 ◽  
Author(s):  
S. P. Ndou ◽  
R. M. Gous ◽  
M. Chimonyo
Keyword(s):  
Feed Intake ◽  
Crude Protein ◽  
Chemical Properties ◽  
Quadratic Functions ◽  
Threshold Values ◽  
Chemical Measurements ◽  
Physico Chemical ◽  
Acid Detergent Fibre ◽  
Water Holding ◽  
Weaner Pigs

The objective of the present study was to predict scaled feed intake (SFI) using the physico-chemical measurements of feed bulk, such that gut capacity can be estimated in weaner pigs. A basal feed with 13·7 MJ digestible energy and 180 g crude protein per kg DM was diluted to six inclusion levels (0, 80, 160, 240, 320 and 400 g/kg DM) using lucerne hay, maize cob, maize stover, sawdust, sunflower husks or grass hay (veld grass). A total of 124 pigs weighing 18·1 (sd1·37) kg body weight were used. Water-holding capacity (WHC; g water/g DM), bulk density (g DM/ml), neutral-detergent fibre (NDF) and acid-detergent fibre (ADF) influenced the SFI. The quadratic relationship between SFI and WHC was SFI = 19·1 (sem3·49)+10·04 (sem1·61) WHC–1·11 (sem0·17) WHC2(P< 0·01). SFI was also related (P< 0·01) to NDF and ADF by quadratic functions SFI = 24·3 (sem3·55)+0·12 (sem0·229) NDF − 0·00 012 (sem0·000036) NDF2and SFI = 30·2 (sem1·95)+0·112 (sem0·0232) ADF–0·000343 (sem0·0000612) ADF2, respectively. Using broken-stick analyses, the gut capacity was attained when WHC = 4·53 (sem1·25) g water/g DM, NDF = 367 (sem29) g/kg DM and ADF = 138 (sem77) g/kg DM. In conclusion, although threshold values for each were different, WHC, NDF and ADF contents of bulk feeds provide relationships with SFI that can be used to predict gut capacity in weaner pigs.

scholarly journals Use of Sentinel 2 – MSI for water quality monitoring at Alqueva reservoir, Portugal

2018 ◽  
Vol 380 ◽  
pp. 73-79 ◽  
Author(s):  
Miguel Potes ◽  
Gonçalo Rodrigues ◽  
Alexandra Marchã Penha ◽  
Maria Helena Novais ◽  
Maria João Costa ◽  
...  
Keyword(s):  
Water Quality ◽  
Chlorophyll A ◽  
Chemical Properties ◽  
Late Summer ◽  
Water Quality Monitoring ◽  
Alqueva Reservoir ◽  
Total Capacity ◽  
Prediction Systems ◽  
Remote Sensing Techniques ◽  
Sentinel 2

Abstract. Alqueva reservoir located in southeast of Portugal has a surface area of 250 km2 and total capacity of 4150 hm3. Since 2006 the water quality of this reservoir is explored by the authors using remote sensing techniques. First using MERIS multi-spectral radiometer on-board of ENVISAT-1 and presently with MSI multi-spectral radiometer on-board SENTINEL-2. The existence of two satellites (A and B) equipped with MSI enable the area to be revisited, under the same viewing conditions, every 2–3 days. Since 2017 the multidisciplinary project ALOP (ALentejo Observation and Prediction systems) expands the team knowledge about the physical and bio-chemical properties of the reservoir. This project includes an integrated field campaign at different experimental sites in the reservoir and its shores, at least until September 2018. Previous algorithms developed by the team for MERIS are tested with the new MSI instrument for water turbidity, chlorophyll a concentration and density of cyanobacteria. Results from micro-algae bloom occurred in late summer/early autumn 2017 on the reservoir are presented, showing the capabilities of MSI sensor for detection and high resolution mapping over the reservoir. The results are compared with in situ sampling and laboratorial analysis of chlorophyll a associated with the bloom.

scholarly journals A review on biochar as a potential soil fertility enhancer to agriculture

2021 ◽  
Vol 6 (1) ◽  
pp. 108-113
Author(s):  
A. Kandel ◽  
S. Dahal ◽  
S. Mahatara
Keyword(s):  
Chemical Properties ◽  
Soil Bulk Density ◽  
Crop Productivity ◽  
Environmental Benefits ◽  
Oxygen Deficit ◽  
Soil Parameters ◽  
Degraded Land ◽  
Wide Range ◽  
Rich Material ◽  
Physical And Chemical

Biochar is a carbon rich material produced from the pyrolysis of biomass at high temperature under oxygen deficit condition. It is recently introduced as one of the effective soil amendments with wide range of environmental benefits. This paper summarizes and discusses the effects of biochar on different soil parameters and crop productivity by reviewing scientific studies conducted around the globe. The benefit is derived especially from the improved soil physical and chemical properties through improvement in soil moisture content, soil bulk density, nitrogen uptake and availability and retention of other soil nutrients, but its effect is highly dependent on feedstocks used, pyrolysis temperature and soil types. It has been found to be more effective on infertile and degraded land. Further research is required to completely reveal the capacity of biochar in enhancing the soil characteristics.

scholarly journals Deep-water inflow event increases sedimentary phosphorus release on a multi-year scale

2021 ◽  
Author(s):  
Astrid Hylén ◽  
Sebastiaan J. van de Velde ◽  
Mikhail Kononets ◽  
Mingyue Luo ◽  
Elin Almroth-Rosell ◽  
...  
Keyword(s):  
Deep Water ◽  
Oxygen Depletion ◽  
Inorganic Phosphorus ◽  
Phosphorus Release ◽  
Water Inflow ◽  
Low Oxygen ◽  
In Situ Experiment ◽  
Inflow Event ◽  
Bottom Waters ◽  
The Baltic

Abstract. Phosphorus fertilisation (eutrophication) is expanding oxygen depletion in coastal systems worldwide. Under low-oxygen bottom-water conditions, phosphorus release from the sediment is elevated which further stimulates primary production. It is commonly assumed that re-oxygenation could break this ‘vicious cycle’ by increasing sedimentary phosphorus retention. Recently, a deep-water inflow into the Baltic Sea created a natural in-situ experiment that allowed us to investigate if temporary re-oxygenation stimulates sedimentary retention of dissolved inorganic phosphorus (DIP). Surprisingly, during this three-year-long study, we observed a transient but considerable increase, rather than a decrease, in the sediment efflux of DIP and other dissolved biogenic compounds. This suggested that the oxygenated inflow elevated the organic matter degradation in the sediment. As a result, the net sedimentary DIP release per m2 was 35–70 % higher over the years following the re-oxygenation than before. In contrast to previous assumptions, our results show that inflows of oxygenated water to anoxic bottom waters can increase the sedimentary phosphorus release.

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