Predicting End-of-Summer Oxygen Profiles in Stratified Lakes

1992 ◽  
Vol 49 (11) ◽  
pp. 2363-2372 ◽  
Author(s):  
L. A. Molot ◽  
P. J. Dillon ◽  
B. J. Clark ◽  
B. P. Neary
Keyword(s):  
Dissolved Oxygen ◽  
Regression Model ◽  
Total Phosphorus ◽  
Multivariate Regression ◽  
Phosphorus Concentration ◽  
Lake Morphometry ◽  
Multivariate Regression Model ◽  
Total Phosphorus Concentration ◽  
Stratified Lakes ◽  
Oxygen Profiles

Mean end-of-summer dissolved oxygen profiles in the hypolimnion of oligotrophic and oligomesotrophic thermally stratified lakes were accurately predicted with a multivariate regression model. The model integrates the effects of lake morphometry, total phosphorus concentration (TP), and initial O2 concentrations at spring turnover to predict mean end-of-summer O2 concentration within individual hypolimnetic strata. Lake morphometry exerts a large influence on O2 profiles and this influence is particularly evident in shallow (< 20 m maximum depth) oligotrophic lakes. Predictions of O2 profiles are sensitive to changes in TP concentrations, with all study lakes predicted to have severely O2-depleted hypolimnions by the end of summer at an epilimnetic TP of only 15 μg∙L−1.

Forest harvest impacts on water quality and aquatic biota on the Boreal Plain: introduction to the TROLS lake program

2001 ◽  
Vol 58 (2) ◽  
pp. 421-436 ◽  
Author(s):  
E E Prepas ◽  
B Pinel-Alloul ◽  
D Planas ◽  
G Méthot ◽  
S Paquet ◽  
...  
Keyword(s):  
Total Phosphorus ◽  
Drainage Basin ◽  
Zooplankton Biomass ◽  
Phosphorus Concentration ◽  
Zooplankton Abundance ◽  
Total Phosphorus Concentration ◽  
Buffer Strip ◽  
Stratified Lakes ◽  
Lake Volume ◽  
Order Of Magnitude

Eleven headwater lakes in Alberta's Boreal Plain were monitored for nutrients and plankton 2 years before and 2 years after variable watershed harvesting (harvesting mean 15%, range 0-35%). After harvesting, variations in annual precipitation resulted in lake water residence times that differed by an order of magnitude from one year to the next. During the first posttreatment year, total phosphorus concentrations increased (overall 40%) in most lakes; however, response was most consistent in lakes that were shallow and the water column mixed or weakly thermally stratified. Chlorophyll a, cyanobacteria (Aphanizomenon-Anabaena), and cyanotoxins (microcystin-LR) increased after harvesting, primarily in shallow lakes. Zooplankton abundance and biomass decreased after harvesting, particularly in stratified lakes where edible phytoplankton biomass declined. In the weakly or nonstratified lakes, declines in zooplankton biomass were associated with higher cyanobacterial biomass and cyanotoxins. Posttreatment change in total phosphorus concentration was strongly related to weather (greatest response in a wet year) and relative drainage basin size (drainage basin area to lake volume, r2 = 0,78, P << 0,01). There was no evidence that buffer strip width (20, 100, and 200 m) influenced lake response. These results suggest that activities within the entire watershed should be the focus of catchment-lake interactions.

Comparison of the Phosphorus–Chlorophyll Relationships in Mixed and Stratified Lakes

1985 ◽  
Vol 42 (4) ◽  
pp. 831-835 ◽  
Author(s):  
E. T. Riley ◽  
E. E. Prepas
Keyword(s):  
Chlorophyll A ◽  
Total Phosphorus ◽  
Phosphorus Concentration ◽  
Total Phosphorus Concentration ◽  
Chlorophyll A Concentration ◽  
Chl A ◽  
Stratified Lakes ◽  
The Mean

Data from the literature were used to calculate separate regressions of summer chlorophyll a concentration ([Chl a]) on spring total phosphorus concentration ([TP]) for lakes that remain thermally stratified during the summer and lakes that mix intermittently during the summer. Significant differences were found in the spring [TP] – summer [Chl a] relationships for the two lake types (P < 0.05). The mean ratios of summer [TP] to spring [TP] were also significantly different in stratified and mixed lakes (P < 0.001); this difference is the explanation offered for why the spring [TP] – summer [Chl a] relationships were different in stratified and mixed lakes.

Lake Paranoá, Brasília, Brazil: Integrated Management Plan for its Restoration

1992 ◽  
Vol 27 (2) ◽  
pp. 271-286 ◽  
Author(s):  
Sonia Paulino Mattos ◽  
Irene Guimarães Altafin ◽  
Hélio José de Freitas ◽  
Cristine Gobbato Brandão Cavalcanti ◽  
Vera Regina Estuqui Alves
Keyword(s):  
Total Phosphorus ◽  
Drainage Basin ◽  
Integrated Management ◽  
Algal Growth ◽  
Nutrient Content ◽  
Management Plan ◽  
Cylindrospermopsis Raciborskii ◽  
Phosphorus Concentration ◽  
Limiting Factor ◽  
Total Phosphorus Concentration

Abstract Built in 1959, Lake Paranoá, in Brasilia, Brazil, has been undergoing an accelerated process of nutrient enrichment, due to inputs of inadequately treated raw sewage, generated by a population of 600,000 inhabitants. Consequently, it shows high nutrient content (40 µg/L of total phosphorus and 1800 µg/L of total nitrogen), low transparency (0.65 m) and high levels of chlorophyll a (65 µg/L), represented mainly by Cylindrospermopsis raciborskii and sporadic bloom of Microcystis aeruginosa, which is being combatted with copper sulphate. With the absence of seasonality and a vertical distribution which is not very evident, the horizontal pattern assumes great importance in this reservoir, in which five compartments stand out. Based on this segmentation and on the identification of the total phosphorus parameter as the limiting factor for algal growth, mathematical models were developed which demonstrate the need for advanced treatment of all the sewage produced in its drainage basin. With this, it is expected that a process of restoration will be initiated, with a decline in total phosphorus concentration to readings below 25 µg/L. Additional measures are proposed to accelerate this process.

scholarly journals L2,1-norm regularized multivariate regression model with applications to genomic prediction

2021 ◽  
Author(s):  
Alain J Mbebi ◽  
Hao Tong ◽  
Zoran Nikoloski
Keyword(s):  
Variable Selection ◽  
Regression Model ◽  
Multivariate Regression ◽  
Statistical Testing ◽  
Supplementary Information ◽  
Nucleotide Polymorphisms ◽  
Multiple Traits ◽  
Multivariate Regression Model ◽  
Proposed Model ◽  
Iterative Optimization Algorithm

AbstractMotivationGenomic selection (GS) is currently deemed the most effective approach to speed up breeding of agricultural varieties. It has been recognized that consideration of multiple traits in GS can improve accuracy of prediction for traits of low heritability. However, since GS forgoes statistical testing with the idea of improving predictions, it does not facilitate mechanistic understanding of the contribution of particular single nucleotide polymorphisms (SNP).ResultsHere, we propose a L2,1-norm regularized multivariate regression model and devise a fast and efficient iterative optimization algorithm, called L2,1-joint, applicable in multi-trait GS. The usage of the L2,1-norm facilitates variable selection in a penalized multivariate regression that considers the relation between individuals, when the number of SNPs is much larger than the number of individuals. The capacity for variable selection allows us to define master regulators that can be used in a multi-trait GS setting to dissect the genetic architecture of the analyzed traits. Our comparative analyses demonstrate that the proposed model is a favorable candidate compared to existing state-of-the-art approaches. Prediction and variable selection with datasets from Brassica napus, wheat and Arabidopsis thaliana diversity panels are conducted to further showcase the performance of the proposed model.Availability and implementation: The model is implemented using R programming language and the code is freely available from https://github.com/alainmbebi/L21-norm-GS.Supplementary informationSupplementary data are available at Bioinformatics online.

scholarly journals Rectal Staphylococcus aureus Carriage and Recurrence After Endoscopic Sinus Surgery for Chronic Rhinosinusitis With Nasal Polyps: A Prospective Cohort Study

2021 ◽  
pp. 014556132110197
Author(s):  
Yue Peng ◽  
Zhao Liu ◽  
Zhijian Yu ◽  
Aiwu Lu ◽  
Tao Zhang
Keyword(s):  
Staphylococcus Aureus ◽  
Cohort Study ◽  
Regression Model ◽  
Chronic Rhinosinusitis ◽  
Endoscopic Sinus Surgery ◽  
Prospective Cohort ◽  
Multivariate Regression ◽  
Nasal Polyps ◽  
Sinus Surgery ◽  
Multivariate Regression Model

Objective: Chronic rhinosinusitis with nasal polyps (CRSwNPs) remains a major challenge due to its high recurrence rate after endoscopic sinus surgery (ESS). We aimed to investigate the risk factors of recurrence among patients who underwent ESS for Chronic rhinosinusitis (CRS). Methods: Prospective cohort study including 391 cases in a single institution receiving ESS were included for analysis from 2014 and 2017. Baseline characteristics including rectal Staphylococcus aureus ( S aureus) carriage in patients receiving ESS for CRSwNPs. The primary outcome was the recurrence of CRSwNPs. Multivariate regression model was established to identify independently predictive factors for recurrence. Results: Overall, 142 (36.3%) cases with recurrence within 2 years after ESS were observed in this study. After variable selection, multivariate regression model consisted of 4 variables including asthma (odds ratio [OR] = 3.41; P < .001), nonsteroidal anti-inflammatory drug allergy (OR = 2.27; P = .005), previous ESS (OR = 3.64; P < .001), and preoperative carriage of S aureus in rectum (OR = 2.34; P = .001). Conclusions: Based on our results, surgeons could predict certain groups of patients who are at high risk for recurrence after ESS. Rectal carriage of S aureus is more statistically related to the recurrence of CRSwNP after ESS compared with skin and nasal carriage.

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