Factors influencing concentrations of polychlorinated biphenyls in organisms from an estuarine ecosystem

1982 ◽  
Vol 33 (6) ◽  
pp. 1057 ◽  
Author(s):  
GR Shaw ◽  
DW Connell
Keyword(s):  
Polychlorinated Biphenyls ◽  
Direct Relationship ◽  
Steric Effect ◽  
Laboratory Data ◽  
River Estuary ◽  
Sediment Concentration ◽  
Food Sources ◽  
Major Influence ◽  
Log P ◽  
Estuarine Ecosystem

Polychlorinated biphenyls (PCB's) were detected in both the abiotic and biotic components of the Brisbane River estuary. Maximum average concentrations were detected in the muscle tissue of pelican (8.2 mg kg-1), gull (2.6 mg kg-1) and catfish (2.1 mg kg-1). Biomagnification was shown not to be a significant factor controlling PCB concentrations in the organisms investigated except in pelicans and gulls. In these cases, estimates of uptake from food sources indicated that biomagnification could be the major process involved. Metabolism or excretion was also found to influence the observed PCB composition of these organisms. Field and laboratory data indicated that, with some benthic organisms, sediment concentrations were the major influence on body concentrations of PCB's and a direct relationship between body concentration and the log of sediment concentration was established. Further laboratory experiments indicated that the uptake of individual PCB's was influenced primarily by two factors: the partition coefficient of n-octanol to water (p) and stereochemical effects. A direct relationship between uptake and the product of log p and the steric effect coefficient was demonstrated. Thus, maximum uptake was found with penta- and hexachlorobiphenyls, predominant in Arochlor 1254. Comparatively less uptake was found with di-, tri- and tetrachlorobiphenyls (Arochlor 1242), which have lower values for log p, and hepta- and octachlorobiphenyls, predominant in Arochlor 1260, which have lower steric effect coefficients.

scholarly journals Spatial and Temporal Variability of Soil Salinity in the Yangtze River Estuary Using Electromagnetic Induction

2021 ◽  
Vol 13 (10) ◽  
pp. 1875
Author(s):  
Wenping Xie ◽  
Jingsong Yang ◽  
Rongjiang Yao ◽  
Xiangping Wang
Keyword(s):  
Electrical Conductivity ◽  
Spatial Distribution ◽  
Soil Salinity ◽  
Yangtze River ◽  
Laboratory Data ◽  
River Estuary ◽  
Yangtze River Estuary ◽  
Soil Electrical Conductivity ◽  
The Yangtze River ◽  
The Yangtze River Estuary

Soil salt-water dynamics in the Yangtze River Estuary (YRE) is complex and soil salinity is an obstacle to regional agricultural production and the ecological environment in the YRE. Runoff into the sea is reduced during the impoundment period as the result of the water-storing process of the Three Gorges Reservoir (TGR) in the upper reaches of the Yangtze River, which causes serious seawater intrusion. Soil salinity is a problem due to shallow and saline groundwater under serious seawater intrusion in the YRE. In this research, we focused on the temporal variation and spatial distribution characteristics of soil salinity in the YRE using geostatistics combined with proximally sensed information obtained by an electromagnetic induction (EM) survey method in typical years under the impoundment of the TGR. The EM survey with proximal sensing method was applied to perform soil salinity survey in field in the Yangtze River Estuary, allowing quick determination and quantitative assessment of spatial and temporal variation of soil salinity from 2006 to 2017. We developed regional soil salinity survey and mapping by coupling limited laboratory data with proximal sensed data obtained from EM. We interpreted the soil electrical conductivity by constructing a linear model between the apparent electrical conductivity data measured by an EM 38 device and the soil electrical conductivity (EC) of soil samples measured in laboratory. Then, soil electrical conductivity was converted to soil salt content (soil salinity g kg−1) through established linear regression model based on the laboratory data of soil salinity and soil EC. Semivariograms of regional soil salinity in the survey years were fitted and ordinary kriging interpolation was applied in interpolation and mapping of regional soil salinity. The cross-validation results showed that the prediction results were acceptable. The soil salinity distribution under different survey years was presented and the area of salt affected soil was calculated using geostatistics method. The results of spatial distribution of soil salinity showed that soil salinity near the riverbanks and coastlines was higher than that of inland. The spatial distribution of groundwater depth and salinity revealed that shallow groundwater and high groundwater salinity influenced the spatial distribution characteristics of soil salinity. Under long-term impoundment of the Three Gorges Reservoir, the variation of soil salinity in different hydrological years was analyzed. Results showed that the area affected by soil salinity gradually increased in different hydrological year types under the impoundment of the TGR.

scholarly journals The Response of Turbidity Maximum to Peak River Discharge in a Macrotidal Estuary

Water ◽  
2021 ◽  
Vol 13 (1) ◽  
pp. 106
Author(s):  
Yuhan Yan ◽  
Dehai Song ◽  
Xianwen Bao ◽  
Nan Wang
Keyword(s):  
River Discharge ◽  
Recovery Time ◽  
Morphological Evolution ◽  
Spring Tide ◽  
River Estuary ◽  
Sediment Concentration ◽  
Ocean Model ◽  
Turbidity Maximum ◽  
Sediment Supply ◽  
Three Dimensional Model

The Ou River, a medium-sized river in the southeastern China, is examined to study the estuarine turbidity maximum (ETM) response to rapidly varied river discharge, i.e., peak river discharge (PRD). This study analyzes the difference in ETM and sediment transport mechanisms between low-discharge and PRD during neap and spring tides by using the Finite-Volume Community Ocean Model. The three-dimensional model is validated by in-situ measurements from 23 April to 22 May 2007. In the Ou River Estuary (ORE), ETM is generally induced by the convergence between river runoff and density-driven flow. The position of ETM for neap and spring tides is similar, but the suspended sediment concentration during spring tide is stronger than that during neap tide. The sediment source of ETM is mainly derived from the resuspension of the seabed. PRD, compared with low-discharge, can dilute the ETM, but cause more sediment to be resuspended from the seabed. The ETM is more seaward during PRD. After PRD, the larger the peak discharge, the longer the recovery time will be. Moreover, the river sediment supply helps shorten ETM recovery time. Mechanisms for this ETM during a PRD can contribute to studies of morphological evolution and pollutant flushing.

scholarly journals ANALISIS KECEPATAN JATUH SEDIMEN PADA SUNGAI CIBEET, JAWA BARAT

2021 ◽  
Vol 5 (1) ◽  
pp. 45
Author(s):  
Kevin Wijaya Warsito ◽  
Wati Astriningsih Pranoto
Keyword(s):  
Conceptual Understanding ◽  
Settling Velocity ◽  
Soil Mechanics ◽  
River Estuary ◽  
Sediment Concentration ◽  
Water And Sediment ◽  
Sediment Research ◽  
Hydraulics Laboratory ◽  
The Relationship ◽  
Optimum Salinity

Cibeet River is one of the branch of the Citarum river in West Java province with a length of 101 km. Cibeet River is one of the rivers supplying water and sediment to the West Tarum irrigation channel or known as the Kalimalang. In this research, the sample used was in the form of mud taken at the Cibeet River Estuary. This research is focused on settling velocity which is a parameter for sedimentation in order to improve numerical modeling and conceptual understanding of sediment dynamics, especially mud. Sediment research is carried out in the Soil Mechanics laboratory and Hydraulics laboratory. Bottom withdrawal tube experiments were carried out using 5 types of salinity and 6 kinds of sediment concentrations. The purpose of the study was to obtain settling velocity and compare laboratory results with the Stokes law approach and compare the relationship between settling velocity with sediment concentration and salinity. The optimum salinity is obtained at 15 ‰, and the optimum sediment concentration at 4700 ppm with an average fall speed of 37,28 mm / s. The results from the laboratory are not in accordance with the Stokes law due to the influence of flocculation from the cohesive nature of the mud sediment, so that using the Stokes law approach cannot calculate the velocity of falling sediment on the mud. Keywords: concentration; salinity; sediment; settling velocity AbstrakSungai Cibeet merupakan salah satu anak sungai dari sungai Citarum di provinsi Jawa Barat dengan panjang 101 km. Sungai Cibeet merupakan salah satu sungai pemasok air dan sedimen ke saluran irigasi Tarum Barat atau dikenal sebagai Kalimalang. Pada penelitian ini, sampel yang digunakan berupa lumpur yang diambil di Muara Sungai Cibeet. Penelitian ini difokuskan pada kecepatan jatuh sedimen yang merupakan parameter untuk sedimentasi demi meningkatkan permodelan numerik dan pemahaman konsep dari dinamika sedimen terutama lumpur.  Penelitian ini dilakukan di laboratorium Mekanika Tanah dan laboratorium Hidrolika, memakai bottom withdrawal tube, dilakukan dengan menggunakan 5 macam jenis salinitas dan 6 macam konsentrasi sedimen.  Penelitian ini membandingkan antara hasil laboratorium dengan pendekatan yaitu hukum Stokes serta membandingkan hubungan antara konsentrasi sedimen dengan salinitas. Untuk salinitas didapat optimum pada saat 15‰, dan konsentrasi sedimen yang optimum pada saat 4700 ppm dengan kecepatan jatuh rata-rata 37,28 mm/s. Hasil dari laboratorium tidak sesuai dengan pendekatan hukum stokes dikarenakan adanya pengaruh flokulasi dari sifat sedimen lumpur yang kohesif, sehingga menggunakan pendekatan hukum stokes tidak bisa untuk menghitung kecepatan jatuh sedimen pada lumpur.

scholarly journals P1479HIGHER FREQUENCY OF FRUIT INTAKE IS ASSOCIATED WITH LOWER RISK OF CONSTIPATION IN HEMODIALYSIS PATIENTS - A MULTI-CENTRE STUDY

2020 ◽  
Vol 35 (Supplement_3) ◽  
Author(s):  
Rafaela G Dos Santos ◽  
Juliana Malinovski ◽  
Natália Scatone ◽  
Jorgiane De Oliveira ◽  
Andrea Sczip ◽  
...  
Keyword(s):  
Regression Analysis ◽  
Dietary Fiber ◽  
Univariate Analysis ◽  
Laboratory Data ◽  
Gastrointestinal Disorder ◽  
Food Sources ◽  
Fruit Intake ◽  
Analysis Model ◽  
Cross Sectional ◽  
Multi Centre Study

Abstract Background and Aims Constipation is a multifactorial gastrointestinal disorder commonly found in hemodialysis (HD) patients. In this multi-centre cross-sectional study, we aimed to evaluate the prevalence and factors associated with constipation, including the frequency of dietary fiber sources intake. Method Prevalent HD patients from four dialysis clinics in Southern Brazil were invited to participate (at least 80% of eligible patients from each clinic). Patients were interviewed by the researchers and answered a questionnaire that comprised ROMA III criteria questions to assess constipation status, use of medications and life habits. A food frequency questionnaire (FFQ) with the main dietary fiber sources (fruits, vegetables, legumes, whole grains cereals and seeds) was applied with seven frequency possibilities (from never to more than twice a day). To estimate the weekly frequency of intake, answers were transformed into a score. Every score point corresponded to one time per week (ex.: score 7 = seven times per week). Demographical and laboratory data were obtained from medical records. Univariate analysis was used to compare participants according to constipation status and variables with P<0.20 were included in the regression analysis model. Results 305 HD patients were included (male: 51%; age: 52.2 ± 14.7 years old; HD vintage: 46 (19 – 82) months). Ninety-three participants had constipation (30.5%). Median (interquartile) FFQ scores were: fruits: 6 (2-14); vegetables: 6 (3-10); legumes: 3 (1-7); whole-grain: 0 (0-1) and seeds: 0 (0-0). In univariate analysis, participants with constipation were significantly older (55.1 ± 14.8 versus 51.0 ± 14.5 years old; P=0.02), had lower literacy (5 (5-11) versus 8 (4-13) years at school; P=0.007), higher prevalence of diabetes (41 versus 23%; P=0.002) and lower total beverage intake (15 (12-20) versus 17 (12-24) ml/kg/day; P=0.04). The logistic regression analysis model also included body mass index; wheelchair need; sedentarism; fruits score and seeds score (all with P<0.20 in the univariate analysis).The independent predictors of constipation were diabetes (OR=1.96 (95%IC 1.07-3.6);P=0.03) and fruits intake score (OR=0.95 (95%IC 0.91-0.99);P=0.04) Conclusion Almost one-third of participants had constipation, and usual intake of fiber food sources was low. The independent determinants of constipation were diabetes and a lower frequency of fruit intake. Nutritional counselling to increase fiber intake sources can potentially decrease the prevalence of constipation of this population.

scholarly journals Identifying the Driving Factors of Black Bloom in Lake Bay through Bayesian LASSO

2019 ◽  
Vol 16 (14) ◽  
pp. 2492 ◽  
Author(s):  
Wang ◽  
Wang ◽  
Cheng ◽  
Cheng
Keyword(s):  
Policy Development ◽  
Sediment Concentration ◽  
Ordinary Least Squares ◽  
Complex Problem ◽  
Regression Equation ◽  
Management Policy ◽  
Major Influence ◽  
Chaohu Lake ◽  
Regression Equations ◽  
Lasso Regression

Black blooms are a serious and complex problem for lake bays, with far-reaching implications for water quality and drinking safety. While Fe(II) and S(−II) have been reported as the most important triggers of this phenomenon, little effort has been devoted in investigating the relationships between Fe(II) and S(−II) and the host of potentially important aquatic factors. However, a model involving many putative predictors and their interactions will be oversaturated and ill-defined, making ordinary least squares (OLS) estimation unfeasible. In such a case, sparsity assumption is typically required to exclude the redundant predictors from the model, either through variable selection or regularization. In this study, Bayesian least absolute shrinkage and selection operator (LASSO) regression was employed to identify the major influence variables from 11 aquatic factors for Fe(II), S(−II), and suspended sediment concentration (SSC) in the Chaohu Lake (Eastern of China) bay during black bloom maintenance. Both the main effects and the interactions between these factors were studied. The method successfully screened the most important variables from many items. The determination coefficients (R2) and adjusted determination coefficients (Adjust R2) showed that all regression equations for Fe(II), S(-II), and SSC were in good agreement with the situation observed in the Chaohu Lake. The outcome of correlation and LASSO regression indicated that total phosphorus (TP) was the single most important factor for Fe(II), S(-II), and SSC in black bloom with explanation ratios (ERs) of 76.1% , 37.0%, and 12.9%, respectively. The regression results showed that the interaction items previously deemed negligible have significant effects on Fe(II), S(−II), and SSC. For the Fe(II) equation, total nitrogen (TN) × dissolved oxygen (DO) and chlorophyll a (CHLA) × oxidation reduction potential (ORP), which contributed 10.6% and 13.3% ERs, respectively, were important interaction variables. TP emerged in each key interaction item of the regression equation for S(−II). Water depth (DEP) × Fe(II) (30.7% ER) was not only the main interaction item, but DEP (5.6% ER) was also an important single factor for the SSC regression equation. It also indicated that the sediment in shallow bay is an important source for SSC in water. The uncertainty of these relationships was also estimated by the posterior distribution and coefficient of variation (CV) of these items. Overall, our results suggest that TP concentration is the most important driver of black blooms in a lake bay, whereas the other factors, such as DO, DEP, and CHLA act in concert with other aquatic factors. There results provide a basis for the further control and management policy development of black blooms.

Swan grazing on seagrass: abundance but not grazing pressure varies over an annual cycle in a temperate estuary

2014 ◽  
Vol 65 (8) ◽  
pp. 738 ◽  
Author(s):  
Gary E. Choney ◽  
Kathryn McMahon ◽  
Paul S. Lavery ◽  
Neil Collier
Keyword(s):  
Annual Cycle ◽  
River Estuary ◽  
Grazing Pressure ◽  
Food Sources ◽  
Spatial And Temporal Variation ◽  
Human Disturbances ◽  
Black Swans ◽  
New Findings ◽  
Cycle Maximum ◽  
Negative Effect

Herbivorous waterfowl such as black swans are significant grazers in temperate waterbodies; their abundance, distribution and grazing rates vary over seasonal cycles. The present study examined spatial and temporal variation in the abundance and grazing rates of black swans in the Lower Swan River estuary, Western Australia, using visual surveys over 1 year (2009), and potential drivers of this variation, food sources and disturbance factors were assessed. We predicted that swan abundance and grazing pressure would be greater in summer and autumn when seasonal wetlands dry and the abundance of food sources would positively influence their distribution, whereas the level of disturbance would have a negative effect. Plant–grazer interactions are dynamic and complex; the present study revealed new findings on the seasonality of this relationship, where swan abundance but not grazing pressure varied over an annual cycle. Maximum swan abundance occurred in autumn (185) with minima in spring (53) but the swan grazing pressure did not vary between seasons, ranging from 6% to 25% of seagrass production consumed. Swan abundance was a function of season and the cover of seagrass. Key hot spots for swan abundance were identified where management efforts could be targeted by minimising human disturbances and protecting seagrass.

Polychlorinated Biphenyls in Sediment and Biota from the Delaware River Estuary

2009 ◽  
Vol 158 (1) ◽  
pp. 89-105 ◽  
Author(s):  
Jeffrey T.F. Ashley ◽  
Megan L. Webster ◽  
Richard J. Horwitz ◽  
David J. Velinsky ◽  
Joel E. Baker
Keyword(s):  
Polychlorinated Biphenyls ◽  
River Estuary ◽  
Delaware River ◽  
Delaware River Estuary

Laboratory testing and in situ behaviour of peat as embankment foundation

1984 ◽  
Vol 21 (2) ◽  
pp. 322-337 ◽  
Author(s):  
G. Lefebvre ◽  
P. Langlois ◽  
C. Lupien ◽  
J.-G. Lavallée
Keyword(s):  
Pore Pressure ◽  
Laboratory Testing ◽  
Lateral Displacement ◽  
Laboratory Data ◽  
Constant Load ◽  
Log P ◽  
Creep Tests ◽  
Special Equipment ◽  
Fibrous Peat ◽  
Pore Pressure Response

Intact block samples of fibrous peat have been obtained using special equipment from two different sites in the James Bay territory in Quebec. Instrumented test fills were subsequently built at those two sites and the observed behaviour was used to check the laboratory data. The laboratory testing program has included standard 24 h incremental tests and stage creep tests where constant loads were applied for periods of about 30 d. Pore pressure and direct permeability measurements were conducted in most of the tests.The tests have been interpreted using the classical e − log p curves or the tangent modulus approach. The evaluation of compression with time under a constant load has allowed the distinction between primary and secondary consolidation. A certain lag in pore pressure response has been observed and related to incomplete saturation. The coefficient of permeability decreases rapidly with compression as indicated by direct measurements and pore pressure dissipation.The comparison with field observation shows that the 24 h incremental oedometric compression test permits a reasonable prediction of the average settlements at the end of primary consolidation provided the lateral displacement during construction is small. It also shows that the secondary compression observed in the field is about twice what was observed in the laboratory but both show a linear relation with the logarithm of time.Keywords: peat, sampling, compressibility, consolidation, secondary consolidation, permeability, laboratory tests, field behaviour.

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