Decrease In Turbidity Research Articles

Влияние ферментативной обработки на качество технологических соков при производстве сахара из бактериально инфицированной сахарной свеклы

Объектом исследований служили корнеплоды инфицированной слизистым бактериозом сахарной свеклы, клеточный сок и полуфабрикаты свеклосахарного производства. Цель исследований заключалась в установлении закономерностей изменения качества технологических соков при введении ферментного препарата гликозидазного действия в процессе экстрагирования сахарозы из бактериально инфицированной сахарной свеклы. Теоретически обоснованы предпосылки применения гликозидазных ферментных препаратов при переработке бактериально инфицированной сахарной свеклы. На основе физического и математического моделирования процессов экстрагирования сахарозы и известково-углекислотной очистки диффузионного сока выявлены зависимости изменения технологических показателей от дозы введения гликозидазного ферментного препарата и степени инфицированности слизистым бактериозом клеточного сока сахарной свеклы. Показана роль ферментативной обработки в улучшении качества технологических соков, в том числе увеличении содержания сахарозы в очищенном соке в среднем на 2,2%, повышении эффекта очистки диффузионного сока в среднем на 3,5%, снижении мутности очищенного сока – на 20%, что может обеспечить повышение качества и выход белого сахара на 1,1%. Достигнуто требуемое состояние пищевой системы с оптимальными (максимальными) показателями величины коэффициента желательности от 0,63 до 0,99, что соответствует хорошему и очень хорошему уровню в зависимости от степени инфицированности корнеплодов. Дальнейшие исследования будут направлены на обоснование условий рационального применения ферментных препаратов гликозидазного действия в оптимальной комбинации совместно с другими технологическими вспомогательными средствами при экстрагировании сахарозы из бактериально инфицированной сахарной свеклы.

The effects of freshwater flow and salinity on turbidity and dissolved oxygen in a shallow Macrotidal estuary: A case study of Portsmouth Harbour

Portsmouth Harbour was used to investigate the effects of fresh water flow and water physio-chemical properties such as salinity on turbidity and dissolved oxygen within industrialised Macrotidal estuaries. Nine sites were selected within the harbour for field sampling and data collection based on their contrasting hydrodynamic environment and accessibility from land. Sediment, water samples and water physio-chemical data were collected from the harbour once every season over a period of two years. Fresh water flow directly affects turbidity as an increase in fresh water flow leads to a decrease in turbidity. Increasing fresh water flow also leads to seaward transport of Suspended particulate matter. There is no significant migration of the estuarine turbidity maxima zone within Portsmouth Harbour due to the general low fresh water flow (average yearly flow of 0.6 m3/s) for all seasons unlike other Macrotidal estuaries. The area of intertidal flats have low dissolved oxygen ranging from about 4.5 mg/L to 10.4 mg/L compared to other areas within the harbour which ranged from 6.5 mg/L to 12.5 mg/L. This is due to the substantial amount of sediment supplied by bed forms such as runnels on the intertidal flats into receiving waters. Based on these findings, there is need for a synchronised management system within these type of estuaries.

A hydroponic green roof system for rainwater collection and greywater treatment

A hydroponic green roof system (HGRS) was developed to reduce urban storm water runoff and to meet the demand of collecting, treating, and reusing grey- and rainwater onsite in green buildings. This system works by treating greywater separately during periods without precipitation and by simultaneous rainwater collection and greywater treatment during rainy periods. Therefore, we first studied the performance of this system when greywater was treated separately under the three hydraulic retention times (HRTs) of 4, 6, and 8 days. Thereafter, we studied this system as it simultaneously collected rainwater and treated greywater under an HRT of 8 days. The results show that, at this HRT, the removal efficiency of organic matter and anionic surfactants, as well as a decrease in turbidity, were quite significant in this system. The average reduction in chemical oxygen demand (COD), five-day biochemical oxygen demand (BOD5), anionic surfactants, and decrease in turbidity reached 81%, 97%, 88%, and 75%, respectively. Microbial sequencing showed the presence of organisms (i.e., Phenylobacterium) in the system that were capable of degrading anionic surfactants. The relative abundance of Phenylobacterium was closely related to the changes in the anionic surfactant concentration, while the microbial species richness gradually increased with extended treatment time. When this system collected rainwater and treated greywater simultaneously, the COD, BOD5, and anionic surfactant concentration in the effluent were lower than when greywater was treated alone, resulting in superior water quality.

Mycosan: сlinical experience and trends in the topical therapy of onychomicosis

Objective — to study the effectiveness and safety of the topical antifungal agent Mycosan in monotherapy of patients with onychomycosis and contraindications to the use of systemic antimycotics.Materials and methods. The questionnaires of 154 patients with a distal-lateral clinical form of onychomycosis and a lesion of not more than two nails on one limb treated with the Mycosan nail kit in 6 regional centers were analyzed. Mycosan nail kit was used according to the instructions. The duration of treatment on average was 3—6 months. All patients underwent clinical and laboratory studies before, during and after treatment. The clinical effect of the therapy was evaluated on the basis of the dynamics of clinical symptoms in scores from 0 (no sign) to 3 (significant sign) at the end of the 4th, 8th, 16th, 24th weeks. Mycological studies were also conducted at these times.Results and discussion. Studies have shown that the use of the Mycosan nail kit in patients with onychomycosis who had contraindications to systemic therapy helped to reduce brittleness, turbidity, and striation at the 4th week of treatment in 40 (25.9 %) patients. At the 8th week of treatment, a decrease in the listed symptoms was observed in 52 (33.8 %) persons, an improvement in the marginal zone — in 85 (55.2 %) persons. A decrease in brittleness, turbidity, striation and density at the 16th week was noted in 148 (96.8 %) patients. The marginal zone became normal in 152 (98.7 %) patients. Hyperkeratotic compactions were absent in 103 (66.9 %) patients. At the 24th week, the state of clinical remission was observed in 52 (33.8 %) patients, significant improvement — in 45 (29.2 %), improvement — in 35 (22.7 %) patients.Mycological negativity at the 4th week was achieved in 20 (13.0 %), at the 8th week — in 33 (21.4 %), at the 16th week — in 52 (33.8 %), at the 24th week — in 82 (53.2 %) patients.According to the analysis of questionnaires on the general assessment of consumer qualities of Mycosan nail kit, it was found that its organoleptic characteristics were rated as «very good» by 39 (25.3%) patients, and «good» — by 115 (74.7%) patients.Conclusions. Mycosan nail kit has a pronounced clinical and mycological effectiveness in eliminating fungal lesions of the nail plates. The drug is well tolerated, does not cause any undesirable manifestations, and contributes to the formation of adherence to therapy in the vast majority of patients. Mycosan is recommended for patients with onychomycosis with a mild degree of damage, in the complex treatment of patients with a more severe degree of damage, in the presence of absolute or relative contraindications to treatment with systemic antifungal drugs, as well as for improvement of the structure of the nail plates and prevention of further destruction of the nails.

High-intensity ultrasonication treatment improved physicochemical and functional properties of mussel sarcoplasmic proteins and enhanced the stability of oil-in-water emulsion

This study investigated the effects of high-intensity ultrasonication (HIUS) treatment (0, 5, 10, 20, 30 min) on the physicochemical and functional properties of mussel sarcoplasmic proteins (MSP). MSP dispersion was treated by HIUS (20 kHz) at 600 W for 5, 10, 20 and 30 min. The results showed that HIUS treatment changed the physicochemical properties of MSP, thereby increasing the stability of the emulsion stabilized by ultrasonicated MSP. HIUS treatment improved the functional properties of MSP, including solubility, foaming ability, foaming stability, emulsifying activity index, emulsifying stability index, percentage of adsorbed proteins. More uniform emulsions with smaller droplets and higher stability were observed. There was a decrease in particle size, zeta-potential and turbidity of ultrasonicated MSP. Proteins partially unfolded as a result of HIUS treatment. Associations between conformation structure, physicochemical properties and functional properties were also found. It can be speculated that improvements in functional properties were caused by the changes in conformation structure and physicochemical properties. The results suggested that HIUS treatment has great potential in modifying the foaming and emulsifying properties of shellfish proteins, and ultrasonication treatment at 20 kHz, 600 W for 20 min was the optimum condition for modification.

Analysis and pretreatment of beauty hair salon wastewater using a rapid granular multimedia filtration system

Discharge of personal care products from salons through the sanitary sewer system has recently become a new generation environmental concern. This study presents a detailed assay of the salon wastewater with emphasis on physicochemical properties such as pH, total organic carbon (TOC), turbidity, electrical conductivity (EC), total dissolved solids (TDS), and chemical composition. Salon wastewater samples were collected directly from two salons in central Johannesburg, South Africa, using the composite sampling method. Determination of physicochemical properties of the wastewater samples was performed before and after pretreatment using the rapid granular multimedia filter. The pH of the wastewater ranged between 7.47 and 9.77, the electrical conductivity was reduced from 344.1 to 312.8 μS cm-1 and from 453 to 412 μS cm-1 for both site 1 and 2 respectively. Pretreatment of the wastewater with the multimedia granular filter resulted in a decline in TDS from 309.5 to 211.4 mg L-1 for site 1 and 315 to 226 mg L-1 for site 2. This was accompanied by a decrease in turbidity of the wastewater. The TOC content declined from a high of 61.5 to about 0.8 mgC L-1. LC-MS analysis of the pretreated wastewater confirmed the presence of several organic compounds with masses ranging from 164.16 to 516.315 g mol-1. This mass range correlate with compounds commonly used in personal care products.

Effect of container geometry on colloids removal from water in oscillation-based flocculation

Abstract Colloid removal in water treatment plants is commonly done by a sequence of processes that includes coagulation, flocculation, sedimentation, and filtration. The current study presents an innovative technique, termed grouping, for the removal of these suspended particles based on physical flow manipulation, which causes the particles to aggregate. Previous results showed that gentle oscillation in a cylindrical container facilitates simultaneous flocculation and sedimentation in the same reactor over shorter periods of time than are possible using the conventional treatment approach. This finding may confer marked improvements on the processes used today by enabling the use of both smaller reactors and less energy. Based on the findings with the cylindrical vessel, here the grouping technique is further examined in a rectangular container and over a range of different initial turbidities. The results indicate that the removal efficiency is higher in the rectangular container under the different initial turbidities tested. In addition, the removal efficiency was shown to remain robust with the decreases in initial turbidity and alum concentrations that occur during treatment. The positive results of our previous study taken together with this finding hint at the strong potential of the grouping technique to improve common flocculation processes.

Controls on redox-sensitive trace metals in the Mauritanian oxygen minimum zone

Abstract. The availability of the micronutrient iron (Fe) in surface waters determines primary production, N2 fixation, and microbial community structure in large parts of the world's ocean, and thus it plays an important role in ocean carbon and nitrogen cycles. Eastern boundary upwelling systems and the connected oxygen minimum zones (OMZs) are typically associated with elevated concentrations of redox-sensitive trace metals (e.g., Fe, manganese (Mn), and cobalt (Co)), with shelf sediments typically forming a key source. Over the last 5 decades, an expansion and intensification of OMZs has been observed and this trend is likely to proceed. However, it is unclear how trace-metal (TM) distributions and transport are influenced by decreasing oxygen (O2) concentrations. Here we present dissolved (d; <0.2 µm) and leachable particulate (Lp; >0.2 µm) TM data collected at seven stations along a 50 km transect in the Mauritanian shelf region. We observed enhanced concentrations of Fe, Co, and Mn corresponding with low O2 concentrations (<50 µmol kg−1), which were decoupled from major nutrients and nutrient-like and scavenged TMs (cadmium (Cd), lead (Pb), nickel (Ni), and copper (Cu)). Additionally, data from repeated station occupations indicated a direct link between dissolved and leachable particulate Fe, Co, Mn, and O2. An observed dFe (dissolved iron) decrease from 10 to 5 nmol L−1 coincided with an O2 increase from 30 to 50 µmol kg−1 and with a concomitant decrease in turbidity. The changes in Fe (Co and Mn) were likely driven by variations in their release from sediment pore water, facilitated by lower O2 concentrations and longer residence time of the water mass on the shelf. Variations in organic matter remineralization and lithogenic inputs (atmospheric deposition or sediment resuspension; assessed using Al as indicator for lithogenic inputs) only played a minor role in redox-sensitive TM variability. Vertical dFe fluxes from O2-depleted subsurface-to-surface waters (0.08–13.5 µmol m−2 d−1) driven by turbulent mixing and vertical advection were an order of magnitude larger than atmospheric deposition fluxes (0.63–1.43 µmol m−2 d−1; estimated using dAl inventories in the surface mixed layer) in the continental slope and shelf region. Benthic fluxes are therefore the dominant dFe supply to surface waters on the continental margins of the Mauritanian upwelling region. Overall, our results indicated that the projected future decrease in O2 concentrations in OMZs may result in increases in Fe, Mn, and Co concentrations.

Parametric Study of COD Reduction from Textile Processing Wastewater Using Adsorption on Cypress Cone-Based Activated Carbon: An Analysis of a Doehlert Response Surface Design

In this study, the performance of a cypress cone-based activated carbon was tested for the COD reduction from industrial textile wastewater. These cypress cones were locally collected after maturation. The Doehlert response surface design was used to simulate and optimize the decrease in COD in treated wastewater. The dominant parameters for COD removal in the effluent were the temperature, the amount of adsorbent and the pH of the initial solution. The obtained model fit the experimental results with high precision (R2 > 0.93) and low Fisher probability ( temperature > initial pH. Under the optimal conditions predicted by the regression, a maximum COD reduction could be obtained with a temperature of 319 K at pH 12 and an activated carbon concentration of 1.144 g L−1 after 1 h treatment. Meanwhile, the designed adsorbent realized the decrease in colour (80.4%), COD (19%) and turbidity (67.1%) of wastewater. It could be concluded that cypress cone-based activated carbon is promising in the treatment of textile wastewater. The increase in COD removal rate through hybridization of processes is being considered for future research.

Transfer of coliform bacteria to duckweed harvested from anaerobic baffled reactor effluent

Efforts to recover nutrients from wastewater have drawn interest in effluent polishing with duckweed, a small angiosperm known to grow in high nutrient environments. One important consideration is that pathogens may be transferred to suspended duckweed biomass and ultimately spread into agricultural or other environmental settings. Our objective was to evaluate transfer of fecal indicator bacteria to duckweed (Lemna minor and Wolffia arrhiza) from anaerobic baffled reactor effluent. The presence of duckweed resulted in significant removal (~1.5-log) of Escherichia coli and >65% decrease in turbidity in reactors. There was E. coli transfer of ~7-log CFU/g from effluent to harvested duckweed, and viable E. coli persisted (at 3.6-log CFU/g) even after several days of biomass drying, representing a health risk for agricultural applications.

Fast and slow biomembrane solubilizing detergents: Insights into their mechanism of action

Detergents are water-soluble amphiphiles. Above a critical concentration they self-organize in micelles and in the presence of phospholipids mixed micelles are formed. Much information is available on the structure of these self-assemblies and on the thermodynamics of their formation. The aim of this study was to deepen our understanding of the mechanisms of solubilization. Solubilization of lipid vesicles made of egg phosphatidylcholine (PC) by twenty one commercially available, structurally heterogeneous detergents, has been assessed by a decrease in turbidity of the vesicle suspension. Both steady-state and time-resolved measurements have been performed. The results show that the detergents under study fall into one of two categories, namely fast-solubilizing and slow-solubilizing detergents. This categorization is independent of detergent concentration, i.e. a “slow” cannot be converted into a “fast” surfactant by increasing its bulk concentration. 31P-NMR spectra indicate that slow-acting detergents cause either a gradual, monotonic micellization of bilayers (sodium dodecyl sulphate), or formation of more complex, perhaps non-lamellar, non-micellar intermediates (dodecylmaltoside). In contrast, fast detergents (e.g. Triton X-100) cause lysis and reassembly of vesicles before bulk solubilization takes place. These results support the idea that membrane solubilization by detergents is rapid only when surfactant transbilayer (flipping) motion is easy.

Variants of the bile: solubility test to differentiate Streptococcus pneumoniae from other viridans group streptococci.

Aim: Bile salts promote the specific autolysis of pneumococcal cells, allowing the differentiation between Streptococcus pneumoniae and other viridans group streptococci (VGS). Material & methods: One hundred clinical VGS isolates identified by amplification and sequencing of 16S rRNA, groEL and sodA genes were analyzed with different variants of bile-solubility tests: tube testing read by naked eye; tube testing where the lysis was measured as the decrease of turbidity with a densitometer; and direct testing on blood agar plate. Results: As expected, all S. pneumoniae isolates were fully lysed in the presence of bile salts except for one isolate that partially lysate in tube testing as well as on the blood agar plate. None of the VGS were lysed by bile salts. Conclusion: Bile-solubility testing is an accurate and technically nondemanding method to discriminate between S. pneumoniae and other VGS species.

Application of the Composite Hydrotalcite (Mg/Al)/Chitosan as Adsorbent for the Treatment of Raw Water of Municipal Waterworks PDAM Bandarmasih

Research has been carried out about raw water treatment of PDAM Bandarmasih by hydrotalcite (Mg/Al) + chitosan (shell of haruan and papuyu fish) adsorbent reviews of decreasing dye value (PtCo), iron (Fe), and turbidity. This research intended to produce drinking water from utilization of fish shell that were still underutilized into chitosan to be matched with hydrotalcite (Mg/Al) with variations of 1, 2 and 3 grams with a duration of 24 hours. The results showed that the decrease in dyestuff value were 96.78%, 95.03% and 92.98%. Persentage decrease in iron (Fe) were 94.38%, 93.78 and 91.87% and percent of turbidity reduction were 97.98%, 79.76% and 76.56%. Best decrease in variations of hydrotalcite (Mg/Al) + chitosan was 1 gram for a duration of 24 hours which resulted in a decrease in dyestuff, iron and turbidity of 11 PtCo, 0.047 mg/L, 0.76 NTU where the results were appropriate in the drinking water requirements in accordance with the Regulation of the Minister of Health of the Republic of Indonesia no:492/MENKES/PES/IV/2010.

PENJERNIHAN AIR SUMUR MENUJU AIR LAYAK MINUM DENGAN METODA LAPISAN MULTI MEDIA ( LMM )

The Multi Soil layering (MSL) system is a liquid waste treatment method with the use of soil as the main medium and the organic material formed in brick and arranged in layers with a homogeneous zeolite layer. The MSL system is made of acrylic (50 x 15 x 50) cm containing a brick (4 x 9 x 15) cm and (4 x 5 x 15) cm of volcanic soil mixture as the main medium mixed with charcoal, rice husk, and iron powder (70 : 10 : 10 : 5)%, permiable layer is used zeolite (2-3) mm. The sample came from the well water of one of villager at Jati, Padang. Efficiency of SML system for aeration process on turbidity parameter with flow rate variation of 2, 4, 6, 8 mL/min reach 99,8 %, for non aeration process efficiency of turbidity decrease 88,14 %. While for the flow rate of 10, 20, 40, 80 mL/min, the efficiency of decrease for aeration at parameters Mn 66,44 %, nitrite 59,74 %, nitrate 58,34 %, turbidity 54,63 %, while in non aeration efficiency decrease turbidity reach 44,04 %, Mn 47,26 %, nitrite 49,74 %, nitrate 45,57 %. Of all efficiency values decreasing all parameters already complied drinking water quality standard according to Permenkes RI No. 492/Menkes/Per/IV/2010.

Modification of rice protein with glutaminase for improved structural and sensory properties

SummaryRice protein is highly nutritive and hypoallergenic but certain physicochemical properties restrict its applications in beverages. This study aimed to tackle this issue by modifying rice endosperm protein with glutaminase via deamidation. Glutaminase treatment facilitated an increase in deamidation degree and mean particle size of rice protein and a continuing decrease in turbidity with time. Favourable changes induced in sensory properties included: improved suspendability (increased by 81.25%), lumpiness (decreased by 84.78%), grittiness (decreased by 72.34%) and overall taste liking (improved by 12.24%). Visual observations of rice protein dispersions and turbidity measurements further confirmed the improved suspendability in water. Fourier transform infrared spectroscopy analysis revealed that the action of glutaminase did not remarkably change the protein structure, but slightly reduced α‐helical conformation whilst increased β‐sheet and β‐turn structures. Glutaminase could be useful for deamidation modification of products with high content of glutamine residues (like rice protein), through inducing the breakdown of some intermolecular and intramolecular bonds including hydrophobic interactions and hydrogen bonding without serious cleavage of the peptide bonds, allowing protein rearrangements to more flexible or extended forms. As a result of protein unfolding with more hydrophobic clusters exposed, certain physicochemical properties of rice protein were improved.

Indirect Assessment of Sedimentation in Hydropower Dams Using MODIS Remote Sensing Images

In this study, we used moderate resolution imaging spectroradiometer (MODIS) satellite images to quantify the sedimentation processes in a cascade of six hydropower dams along a 700-km transect in the Paranapanema River in Brazil. Turbidity field measurement acquired over 10 years were used to calibrate a turbidity retrieval algorithm based on MODIS surface reflectance products. An independent field dataset was used to validate the remote sensing estimates showing fine accuracy (RMSE of 9.5 NTU, r = 0.75, N = 138). By processing 13 years of MODIS images since 2000, we showed that satellite data can provide robust turbidity monitoring over the entire transect and can identify extreme sediment discharge events occurring on daily to annual scales. We retrieved the decrease in the water turbidity as a function of distance within each reservoir that is related to sedimentation processes. The remote sensing-retrieved turbidity decrease within the reservoirs ranged from 2 to 62% making possible to infer the reservoir type and operation (storage versus run-of-river reservoirs). The reduction in turbidity assessed from space presented a good relationship with conventional sediment trapping efficiency calculations, demonstrating the potential use of this technology for monitoring the intensity of sedimentation processes within reservoirs and at large scale.

Numerical simulation and experimental study on a cone-plate clarifier

The large amount of fine and light particles in the mine water are difficult to be removed using the traditional separator. In order to improve the separation efficiency, this article presents a new type of compact cone-plate clarifier with which a hybrid process combining magnetic flocculation separation with hydrocycloning can be achieved for sewage treatment. Addition of cone-plates to the elongated vortex finder provides more possibility for small magnetic flocs to aggregate and form into large flocs as well as increase the sedimentation area. The numerical simulation indicates that the cone-plate is conducive to the agglomeration of small particles in the cylindrical body and favorable for flocs to precipitate steadily in the conical part of the clarifier. Further comparative experiment verifies the effectiveness of the cone-plates. Then, the influence of cylinder height, insertion depth, and spacing of cone-plates on the water quality of the clarifier have been researched, and the optimum structural parameters have been determined. With the optimum parameters—a cylinder height of 600 mm, a cone-plate insertion depth of 400 mm, and plate spacing of 20 mm, a property index of 93.71% for suspended solids removal and 70.17% for turbidity decrease has been obtained for the mine water treatment.

Utilization of plant extract as antimicrobial finish for healthcare textiles

Textile materials are good media for the growth of the microorganisms. The consumers these days are increasingly being aware of the hygienic lifestyle and there is a necessity of development of a wide range of textile products finished with antimicrobial properties. Thus an innovative approach was made to utilize the plant sources as ecofriendly and renewable source for production of microbial resistant fabric. The developed environment-friendly finish prevents the growth of bacteria. It also prevents garments from unpleasant odour. For this the chemical nature of Mousambi and Harshingar leaf extracts was determined and extraction of active substances from the leaves was done using ethanol, methanol and aqueous medium. The herbal extracts were applied on 100 per cent cotton fabric with and without the use of cross linking agent. Eleven concentrations of both the plant extracts were used to study the reduction in bacterial colonies on the fabric. The antimicrobial activity of the finished fabric was assessed using quantitative and qualitative methods against bacteria and fungi that normally exist in the textile environment. The finished cotton fabrics showed the maximum bacterial reduction percentage of 74.7 for Harshingar against Gram positive and 71.2 for Mousambi against Gram negative bacteria. With the increase in concentration of the plant extract a decrease in turbidity was noticed.

Temporal variations in turbidity in an oil sands pit lake

We investigated temporal variations in turbidity in Base Mine Lake, an oil sands pit lake, located in northeast Alberta, Canada. The lake has a surface area of 7.8 km2, is 9 m deep, and exhibits seasonal thermal stratification similar to that of natural dimictic lakes. Water turbidity was measured continuously throughout the year with moored sensors, supplemented with turbidity profiles and bottle samples, from sites on the lake. During summer there was a gradual exponential (e-folding time of 25 days) decrease in epilimnetic turbidity due to relatively steady settling of solids from the epilimnion through the thermocline to the hypolimnion. Rapid oscillations (periods of approximately 1 day) in turbidity during summer were due to wind driven internal waves. Convective cooling and wind-shear driven stirring during fall storm events increased the turbidity to an annual high just before ice-on. During these storm events, similarity scaling indicated wind shear imparted greater energy than convective cooling to the turbulence at the base of the water column. Ice suppressed wind forcing and resulted in a rapid decrease in turbidity. The rate of decrease in turbidity following ice-on was initially greater than the rate of decrease in the epilimnion during summer, and then slowed until the under-ice turbidity was a relatively constant value which was sustained during the latter half of the ice-on period. The minimum turbidity during winter was greater than the minimum during summer. Following ice-melt in spring, wind driven stirring increased turbidity until summer stratification began.

A Diel Method of Estimating Gross Primary Production: 2. Application to 7 Years of Near‐Surface Dissolved Oxygen Data in Chesapeake Bay

AbstractA diel method for estimating gross primary production (GPP) is applied to nearly continuous measurements of near‐surface dissolved oxygen collected at seven locations throughout the main stem of Chesapeake Bay. The data were collected through the Chesapeake Bay Interpretive Buoy System and span the period 2010–2016. At all locations, GPP exhibits pronounced seasonal variability consistent temperature‐dependent phytoplankton growth. At the Susquehanna Buoy, which is located within the estuarine turbidity maximum, rates of GPP are negatively correlated with uncalibrated turbidity data consistent with light limitation at this location. The highest rates of GPP are located immediately down Bay from the estuarine turbidity maximum and decrease moving seaward consistent with nutrient limitation. Rates of GPP at the mouth (First Landing Buoy) are roughly a factor of 3 lower than the rates in the upper Bay (Patapsco). At interannual time scales, the summer (June–July) rate of GPP averaged over all stations is positively correlated (r2 = 0.62) with the March Susquehanna River discharge and a multiple regression model that includes spring river discharge, and summer water temperature can explain most (r2 = 0.88) of the interannual variance in the observed rate of GPP. The correlation with river discharge is consistent with an increase in productivity fueled by increased nutrient loading. More generally, the spatial and temporal patterns inferred using this method are consistent with our current understanding of primary production in the Bay, demonstrating the potential this method has for making highly resolved measurements in less well studied estuarine systems.