Turbidity Maximum Research Articles

Treatment of debrominated wastewater by electrocoagulation using Mild Steel electrodes

Most process industries produce a large amount of effluent which includes bromine, which is valuable for further use. After the separation of valuable bromine from such industrial wastewater, a sizeable amount of debrominated wastewater (DWW) with a large amount of contaminates is left over. Considering the chemical oxygen demand (COD), total dissolved solid (TDS), turbidity, and color parameters, DWW cannot be discharged directly to water bodies. It mandatorily requires to be treated for the removal of various contaminants. Wastewater treatment includes traditional processes like chemical treatment, biological treatment, and physical treatment. Although they have been effective, each process has its limitations and can be energy-intensive and costly. Electrocoagulation (EC) is a highly effective treatment process that has been widely used to treat complex industrial wastewater. To treat DWW, The EC treatment was conducted in a 2-liter batch reactor using Mild Steel electrodes (MS) arranged as four parallel plates. After the treatment achieved maximum color, turbidity, COD, and TDS removal of 71.91%,100%, 36.36%, and 24.95%, respectively, at optimal current intensity 2 A, pH 9, and electrode spacing 1.5 cm. Energy consumption of 3 Wh/L was observed as a maximum at pH 11 and a maximum total metal consumption (TMC) of 2.11 g/L at pH 7. The highest foam and residue weight was 6.81 kg/m3 at pH 9 and the highest sedimentation rate was found at pH 11. Electrocoagulation treatment time was also examined for each parameter such as pH, electrode gap, and current intensity.

Changes over flood season in turbidity maximum zone in a mountainous macrotidal estuary from 1986 to 2020

Changes over flood season in turbidity maximum zone in a mountainous macrotidal estuary from 1986 to 2020

Source, composition, and reactivity of particulate organic matter along the Changjiang Estuary salinity gradient and adjacent sea

The sources, distribution, and fate of particulate organic matter (POM) in estuaries are dynamic and complex, influenced by highly intensive human activities and high productivity. In this study, water samples were collected along the Changjiang Estuary salinity gradient and adjacent sea (CEAS) in February and May 2017. Particulate organic carbon (POC), particulate nitrogen (PN), the δ13C isotope values and major biochemical constituent (total particulate amino acids, TPAA) were measured. The concentrations of POC, PN, and TPAA showed an overall decreasing trend from the river end-member to the open sea; however, their maximum always occurred around the turbidity maximum zone (TMZ). Concentrations of POC and TPAA showed a negative correlation with salinity and a positive correlation with chlorophyll a, indicating that the variation in POM concentrations and composition was mainly controlled by both terrigenous input and in situ phytoplankton production. The δ13C values gradually increased from the river mouth to the open sea in both winter and spring, in contrast to the molar C/N, reflecting the transition from terrestrial POC to phytoplankton-derived fresh POC with increasing salinity. Major biochemical indicators of TPAA/POC (%) and the degradation index (DI), showed a gradual shift towards more bioactive POM with increasing salinity in spring, although low TPAA/POC (%) values appeared within the TMZ. In spring, POC reactivity was higher than in winter. The proportions of glycine (Gly) and serine (Ser) were higher in winter, indicating that POM had suffered extensive degradation. Based on a two end-member mixing model, the contribution of marine POC in spring (53 ± 14%) was significantly greater than in winter (39 ± 19%), indicating that phytoplankton-derived POM was dominant in spring, associated with the increase in phytoplankton biomass from winter to spring. Based on mass balance, a box model showed evidence of a net POC sink over the Changjiang estuary and its adjacent East China Sea shelf in both winter and spring, with a net POC budget of 20.49 ± 7.01 and 15.87 ± 6.57 kmol s−1, respectively. Results illustrate that the spatio-temporal distribution of POM varies distinctively and will further affect the variability in its composition and reactivity in the CEAS.

A storm driven turbidity maximum in a microtidal estuary

Many macro- and mesotidal estuaries are characterized by Turbidity Maxima Zones (TMZs), regions with suspended solid concentrations that are much higher than those found throughout the rest of the estuary. Such regions are located near the upriver limit of salt intrusion and their position and extent are modulated and driven by tidal oscillations, especially in estuaries where tidal forcing is large. Hence, pronounced TMZs are not typically expected in micro-tidal estuaries. Field experiments were carried out in the microtidal estuary of the Misa River (northeast coast of Italy) with the aim to analyze riverine-coastal ocean interactions during different climatic conditions, freshwater discharge and tidal forcing. The goal was also that of identifying factors and episodic conditions that could lead to the evolution of ephemeral TMZs in this microtidal estuarine system. Observational results, combined to a flocculation model suite, describe the hydrodynamics, morphological bed evolution, water chemistry and floc dynamics within the estuary during wintertime quiescent and stormy periods. Pronounced TMZs with different location and extent were observed during two storms with different intensities, when enhanced freshwater discharge, wave action and tidal oscillation generated significant stratification of the lower estuarine water column. Higher turbidity values were observed throughout the TMZ during the smaller/weaker storm, while stronger surface mixing during the stronger storm led to greater dispersion of the (re-)suspended particulate load throughout the upper water column, providing a less pronounced TMZ along the bed of the lower estuary. Observations in the Misa River, potentially valid for other microtidal estuaries, show that: 1) episodic storm conditions that significantly increase freshwater discharge can lead to the evolution of an ephemeral TMZ that is modulated, but not controlled, by tidal oscillations and surface mixing conditions; 2) ephemeral TMZ localization, intensity, and extent during episodic storm events is a function of storm intensity; 3) moderately enhanced freshwater flow during an episodic storm event promotes a high degree of stratification, allowing for the formation of large flocs with great settling rates, leading to a pronounced TMZ forming downriver of the landward limit of seawater intrusion; whereas higher freshwater flows during stronger storm events lead to less stratification, greater bottom turbulence and potential TMZ suppression near the riverbed, with shear conditions promoting smaller flocs with lower settling and a greater potential for suspended particulate export from the lower estuary to coastal waters.

Regulation Mechanism of Nicotine Catabolism in Sphingomonas melonis TY by a Dual Role Transcriptional Regulator NdpR.

A gene cluster ndp, responsible for nicotine degradation via a variant of the pyridine and pyrrolidine pathways, was previously identified in Sphingomonas melonis TY, but the regulation mechanism remains unknown. The gene ndpR within the cluster was predicted to encode a TetR family transcriptional regulator. Deletion of ndpR resulted in a notably shorter lag phase, higher maximum turbidity, and faster substrate degradation when cultivated in the presence of nicotine. Real-time quantitative PCR and promoter activity analysis in wild-type TY and TYΔndpR strains revealed that genes in the ndp cluster were negatively regulated by NdpR. However, complementation of ndpR to TYΔndpR did not restore transcription repression, but, instead, the complemented strain showed better growth than TYΔndpR. Promoter activity analysis indicates that NdpR also functions as an activator in the transcription regulation of ndpHFEGD. Further analysis through electrophoretic mobility shift assay and DNase I footprinting assay revealed that NdpR binds five DNA sequences within ndp and that NdpR has no autoregulation. These binding motifs overlap with the -35 or -10 box or are located distal upstream of the corresponding transcriptional start site. Multiple sequence alignment of these five NdpR-binding DNA sequences found a conserved motif, with two of the binding sequences being partially palindromic. 2,5-Dihydroxypyridine acted as a ligand of NdpR, preventing NdpR from binding to the promoter region of ndpASAL, ndpTB, and ndpHFEGD. This study revealed that NdpR binds to three promoters in the ndp cluster and is a dual-role transcriptional regulator in nicotine metabolism. IMPORTANCE Gene regulation is critical for microorganisms in the environment in which they may encounter various kinds of organic pollutants. Our study revealed that transcription of ndpASAL, ndpTB, and ndpHFEGD is negatively regulated by NdpR, and NdpR also exhibits a positive regulatory effect on PndpHFEGD. Furthermore, 2,5-dihydroxypyridine was identified as the effector molecular for NdpR and can both prevent the binding of free NdpR to the promoter and release NdpR from the promoters, which is different from previously reported NicR2. Additionally, NdpR was found to have both negative and positive transcription regulatory effects on the same target, PndpHFEGD, while only one binding site was identified, which is notably different from the previously reported TetR family regulators. Moreover, NdpR was revealed to be a global transcriptional regulator. This study provides new insight into the complex gene expression regulation of the TetR family.

Change of turbidity maximum in Yangtze Estuary after construction of the Three Gorges Dam

Estuarine turbidity maxima (ETMs) are of sedimentological, geomorphological and ecological significance. In this study, a well-validated and process-based sediment transport model was used to investigate the response of ETM dynamics in the Yangtze Estuary (YE) to construction of the Three Gorges Dam (TGD) and morphological evolution of the YE. The model results demonstrated that the ETM dynamics change in the upper estuary was controlled by the TGD construction. After the TGD construction, the ETM area decreased by 22% (from 1116 to 874 km2) and the ETM center location moved landward 7 km during the flood season. The estuarine morphological evolution played a key role in the ETM dynamics change of the mid-lower estuary. The ETM area decreased by 55% (from 1478 to 658 km2) and 15% (from 658 to 562 km2) due to the estuarine morphological evolution from 1998 to 2010 and from 2010 to 2018, respectively. Meanwhile, the ETM center location moved landward 38 km and 7 km during the periods 1998–2010 and 2010–2018, respectively. Overall, both the TGD construction and estuarine morphological evolution induced decreased suspended sediment concentrations in the estuary. Furthermore, the effect of TGD construction was dominant in the upper estuary, whereas the effect of estuarine morphological evolution became dominant in the mid-lower estuary. These findings provide implications for management of the YE and other similar estuaries.

Modeling and optimization of the coagulation/flocculation process in turbidity removal from water using poly aluminum chloride and rice starch as a natural coagulant aid.

The application of the coagulation/flocculation process is very important due to its simplicity in removing turbidity. Due to the disadvantages of using chemical coagulants in water and the lack of sufficient effect of natural materials alone in removing turbidity for proper performance, the simultaneous use of chemical and natural coagulants is the best way to reduce the harmful effects of chemical coagulants in water. In this study, the application of poly aluminum chloride (PAC) as a chemical coagulant and rice starch as a natural coagulant aid to remove turbidity from aqueous solutions was investigated. Effects of the above coagulants on the four main factors, coagulant dose (0-10mg/L), coagulant adjuvant dose (0-0.1mg/L), pH (5-9), turbidity (NTU 0-50), and each five levels were assessed using a central composite design (CCD). Under the optimized conditions, the maximum turbidity elimination efficiency was found to be 96.6%. The validity and adequacy of the proposed model (quadratic model) were confirmed by the corresponding statistics (i.e., F-value of 23.3, p-values of 0.0001, and lack of fit of 0.877 for the model, respectively, R2 = 0.88, R2adj. = 0.84, R2 pred = 0.79, AP = 22.04).

Three gorges dam shifts estuarine heavy metal risk through suspended sediment gradation

Damming alters downstream sediment supply relationships and erosion in the estuarine delta. Given that sediment grainsize serves as a key parameter for the ability to adsorb heavy metals from water, the assessment of estuarine heavy metal risk needs to get connected initially. Hence, fine suspended sediment (<63 μm) in the Yangtze River estuary (YRE) was divided into four grainsize fractions to simulate the surface suspended sediment concentration (SSC) and grainsize composition before and after the completion of the Three Gorges Dam (TGD). Representative months were selected for flood peak reduction (October) and runoff compensation in the dry season (March) to maximize the scheduling impact of the TGD on runoff and riverine sediment input to the YRE. An improved Water Quality Index (WQI) approach was proposed to assess the combined risk alteration of five heavy metals in six estuarine sensitive targets due to TGD-induced sediment characteristics. The results demonstrated that TGD significantly but tardily reduced the SSC and the proportion of fine sediment in the YRE, decreasing the risk of heavy metals resuspension. Seasonally, the total SSC became higher in the flood season than in the dry season during post-TGD period. However, the fine SSC in the flood season was averaged only 59.7% of that in the dry season due to the pronounced grainsize coarsening effect. As the significant reduction in fine SSC overcomes the increase in heavy metal content per unit of SS, the integrated resuspension risk declined significantly, particularly for Pb and Cr. Spatially, the risk reduction for sensitive targets near the turbidity maximum zone (TMZ) is 8.4 times greater than for inner river channel. However, undiminished anthropogenic metal inputs to the YRE signified greater pressures on the depositional environment.

Applicability of electrocoagulation process for removal of contaminants from debrominated wastewater

Debrominated wastewater (DWW) leftover, after the separation of bromine, from the effluent of various industries like fertilizer, pesticide, pharmaceutical, organic chemicals, etc. contains a large amount of COD, TDS, turbidity and color and cannot be discharged directly to water bodies. The investigation for DWW treatment by electrocoagulation (EC) was performed in a two-liter batch-type reactor using SS electrodes (Fe). With the four-plate configuration, a maximum COD, TDS, color, and turbidity removal of 45.5%, 26%, 86.5%, and 100% were obtained respectively, at their optimum pH 9, current intensity 2 amp, and electrode gap 1.5 cm. The maximum energy consumption of 4.2 Wh/L was observed at pH 5 while the maximum electrode loss (EL) was 1.995 g/L at pH 9. The best settling rate was found at pH 3, and the maximum weight of foam and residue of 7.31 kg/m3 was found at pH 9. Electrolysis time was also observed for all parameters.

Reduction of Turbidity, Color Intensity and COD of Jumputan Wastewater with Electrocogulation Method

The purpose of this study was to determine the effectiveness of the electrocoagulation method in reducing turbidity, color concentration and COD levels on Jumputan wastewater treatment. The electrodes used are aluminum plates as anode and cathode. The variations of the research used were the speed of agitation and the system used (batch and intermittent system). The fixed variable used is a voltage of 3.5 volts, the 2 aluminium electrodes, and 250 ml volume of Jumputan wastewater. The results showed that the maximum turbidity degraded to 99.89% for the batch system at a contact time of 150 minutes with agitation speed of 150 rpm, and 99.97% for intermittent system at a contact time of 60 minutes with agitation speed of 150 rpm. The maximum percentage of color removal reached 58.90% for the batch system at a contact time of 90 minutes with a stirring speed of 50 rpm, and 54.74% for intermittent system at a contact time of 150 minutes with a stirring speed of 150 rpm. The electrocoagulation method could reduce 78.75% of the COD level for the batch system is and 80% for the intermittent system. The intermittent system slightly had more effect on the turbidity, color and COD reduction compared to batch system. Both batch and intermittent system got optimum turbidity and color removal on first 30 minutes of electrocoagulation process. The results prove that electrocoagulation method has been effective as an alternative to reduce COD and turbidity on Jumputan wastewater.

Performance evaluation of hydrodynamic cavitation in combination with AOPs for degradation of tannery wastewater

Tannery wastewater effluent (TWE) consists of a variety of complex structured compounds having very low biodegradability. Few attempts have been made to treat real-time TWE consisting of complex compounds and find the intermediate compounds formed during the HC+PAA+ FeSO4.7 H2O treatment system. Therefore, a pilot scale study has been conducted on an orifice-embedded hydrodynamic cavitation reactor for treating real-time TWE. Liquid chromatography-high resolution mass spectrometry (LC-HRMS) has been carried out to identify the specific compounds present in TWE before and after treatment. Response surface methodology (RSM) – Box-Behnken design (BBD) obtained maximum COD, TDS and turbidity removal efficiency of 72.36%, 94.54% and 98.89%, respectively, at cavitation time-97.5 min, inlet pressure-7.5 bar, pH-2, orifice diameter-0.5 mm, PAA dosage-17.5 g/L, and PAA /FeSO4.7 H2O-2:1 ratio. The reaction rate constant was increased from 2.455 × 10−3 to 12.75 × 10−3 min−1 when AOPs were combined with HC. The study concluded that the degradation using HC+PAA+ FeSO4.7 H2O successfully increased the biodegradability of the TWE without forming any toxic by-products.

Geochemical controls on the distribution and bioavailability of heavy metals in sediments from Yangtze River to the East China Sea: Assessed by sequential extraction versus diffusive gradients in thin-films (DGT) technique

This study conducted a comprehensive investigation on the distribution and bioavailability of heavy metals (Cr, Co, Ni, Cu, Zn, Cd and Pb) in sediments along two typical transects from Yangtze River to the East China Sea continental shelf that spanning large physicochemical gradients. Heavy metals were mainly associated with the fine-grained sediments (enriched with organic matter), exhibiting decreasing trends from nearshore to offshore sites. The turbidity maximum zone showed the highest metal concentrations, which evaluated as polluted for some tested metals (especially Cd) using the geo-accumulation index. Based on the modified BCR procedure, the non-residual fractions of Cu, Zn and Pb were higher within the turbidity maximum zone, and significantly negatively correlated with bottom water salinity. The DGT-labile metals all positively correlated with the acid-soluble metal fraction (especially for Cd, Zn and Cr), and negatively correlated with salinity (except Co). Therefore, our results suggest salinity as the key factor controlling metal bioavailability, which could further modulate metal diffusive fluxes at the sediment-water interface. Considering that DGT probes could readily capture the bioavailable metal fractions, and reflect the impacts of salinity, we suggest DGT technique can be used as a robust predictor for metal bioavailability and mobility in estuary sediments.

Magnetic susceptibilites of suspended sediment and microplastic abundance in a tropical volcanic estuary

Coastal and estuarine ecosystems are seriously threatened by pollutants, according to the literature. In the estuary, the zone that traps suspended particulate matter, namely, estuarine turbidity maxima (ETM), needs to be identified to prevent ecological threats, namely migration and species death. Magnetic measurements of sediments in volcanic rivers have also attracted attention because the sediment contains a high abundance of magnetic minerals. The method in this paper provides a low-cost, rapid, and nondestructive approach to environmental monitorings and assessments. However, the validity of magnetic measurements has not been investigated for their use in identifying the ETM zone in estuaries in volcanic regions. Therefore, this research aims to identify ETM zones in the estuaries of volcanic regions using magnetic properties to correlate the characteristics to microplastic abundance within suspended and surface sediments. The measurements consist of magnetic susceptibility at low frequency, magnetic susceptibility at high frequency, frequency-dependent magnetic susceptibility analyses, and acquisition of a hysteresis curve. Magnetic minerals were also identified using X-ray diffraction and scanning electron microscopy-energy dispersive spectroscopy. The results showed that the values of magnetic susceptibility at low frequency significantly correlate with total dissolved solids and microplastics abundance in sediments. The frequency-dependent magnetic susceptibility values were significantly correlated with total dissolved solids, microplastics abundance, turbidity, and microorganism cells. This phenomenon indicates that the magnetic properties of suspended sediments can be used to identify an ETM zone in estuaries in tropical volcanic regions.

Assessment of Physico-Chemical Parameters of ground water Quality in Agra City

The minimum to maximum temperature value was observed 22ºC to 25.2ºC while pH value ranged between 7.2 (P-9) to 7.9 (P-1) . The minimum to maximum Turbidity value was observed 5 (P-7) to 17.9 (P-11) NTU. The minimum to maximum TDS value was observed 1540 (P-10) to 4950 (mg/l (P-4). The minimum and maximum Total Hardness value was observed 240 (P-3) to 1250 mg/l (P-7) . The minimum to maximum Calcium Hardness value was observed 75(P-3) to 436 mg/l (P-9). The minimum to maximum Magnesium Hardness value was observed 25.6 (P-6) to 139 mg/l (P-9). The highly positive correlated value were found between total hardness and Magnesium (0.944) , TDS and Chloride (0.913). Highly negatively correlated value were, pH and (-0.640).The result comes out of study shows that the ground water in some area are unfit for drinking purposes .

Aplikasi Pengolahan Limbah Batik Menggunakan Membran Keramik Berbiaya Rendah pada Kolom Batch

Batik is a characteristic of Indonesian culture which in the manufacturing process will produce waste as a residue from the colouring process. The waste still has a high colour content so if it is not processed further it will pollute the environment. This study aims to synthesize ceramic membranes from low-cost materials and apply the use of these membranes to treat batik waste in a batch column. The variable used in this study is the processing cycle, the results of the first processing are put back into the batch column for up to 3 iterations. The parameters tested were pH, turbidity and colour testing. The results showed that the ceramic membrane was able to treat batik wastewater with a maximum turbidity rejection % of 86.67 % and a maximum % rejection of 67.51 %. Low-cost ceramic membranes are effective for use as an alternative for batik waste treatment.

Comparing in situ turbidity sensor measurements as a proxy for suspended sediments in North-Western European streams

Climate change in combination with land use alterations may lead to significant changes in soil erosion and sediment fluxes in streams. Optical turbidity sensors can monitor with high frequency and can be used as a proxy for suspended sediment concentration (SSC) provided there is an acceptable calibration curve for turbidity measured by sensors and SSC from water samples. This study used such calibration data from 31 streams in 11 different research projects or monitoring programmes in six Northern European countries. The aim was to find patterns in the turbidity-SSC correlations based on stream characteristics such as mean and maximum turbidity and SSC, catchment area, land use, hydrology, soil type, topography, and the number and representativeness of the data that are used for the calibration. There were large variations, but the best correlations between turbidity and SSC were found in streams with a mean and maximum SSC of >30–200 mg/l, and a mean and maximum turbidity above 60–200 NTU/FNU, respectively. Streams draining agricultural areas with fine-grained soils had better correlations than forested streams draining more coarse-grained soils. However, the study also revealed considerable differences in methodological approaches, including analytical methods to determine SSC, water sampling strategies, quality control procedures, and the use of sensors based on different measuring principles. Relatively few national monitoring programmes in the six countries involved in the study included optical turbidity sensors, which may partly explain this lack of methodological harmonisation. Given the risk of future changes in soil erosion and sediment fluxes, increased harmonisation is highly recommended, so that turbidity data from optical sensors can be better evaluated and intercalibrated across streams in comparable geographical regions.

Implications of a Large River Discharge on the Dynamics of a Tide-Dominated Amazonian Estuary

Estuaries along the Amazonian coast are subjected to both a macrotidal regime and seasonally high fluvial discharge, both of which generate complex circulation. Furthermore, the Amazon River Plume (ARP) influences coastal circulation and suspended sediment concentrations (SSCs). The Gurupi estuary, located south of the mouth of the Amazon River, is relatively unstudied. This study evaluates how the Gurupi estuary dynamics respond to seasonal discharge and the varying influence of the ARP using cross-sectional and longitudinal surveys of morphology, hydrodynamics, and sediment transport. The Gurupi was classified as a tide-dominated estuary based on morphology and mean hydrodynamic conditions. However, the estuary was only partially mixed during both the wet and dry seasons. The tides propagated asymmetrically and hypersynchronously, with flood dominance during the dry season and ebb dominance during the rainy season. Seasonal variations of the ARP did not significantly affect the hydrodynamic structure of the lower Gurupi estuary. Estuarine turbidity maxima (ETM) were observed in both seasons, although the increase in fluvial discharge during the wet season attenuated and shifted the ETM seaward. Little sediment was delivered to the estuary by the river, and the SSCs were higher at the mouth in both seasons. Sediment was strongly imported during the dry season by tidal asymmetry. The morphology, hydrodynamics, and sediment dynamics all highlight the importance of considering both fluvial discharge and coastal influences on estuaries along the Amazon coast.

High sedimentation rates lead to rapid vegetation recovery in tidal brackish wetland restoration

IntroductionTidal wetland restoration in the Bay of Fundy involves restoring tidal hydrology to sites with tidal restrictions. Most have focused on salt marsh sites close to the mouth of estuaries, but there are also many tidally restricted wetlands closer to the freshwater end of tidal rivers. Recovery of salt marsh vegetation has been rapid in past projects, but little is known about sediment and vegetation dynamics post restoration in tidal brackish or freshwater environments.MethodsWe implemented tidal wetland restoration projects on two tidal rivers near the inland limit of saltwater. Hydrological restoration involved breaching (St. Croix) or realigning agricultural dykes (Belcher Street). We monitored hydrology, sediment accretion and vegetation at replicated plots on restoration sites and nearby reference tidal marshes; and conducted habitat mapping and elevation surveys using drones.ResultsAfter re-establishing tidal flow, sediment accretion was very rapid, leading to a deep layer of new sediments. Plant colonization at both sites resulted in a high diversity of halophytes in the first 2 years post restoration, but the St. Croix site transitioned to freshwater wetland species dominating by the fifth year post- restoration. The Belcher St. site has a mix of freshwater and brackish wetland species after the fourth-year post-restoration.DiscussionHigh suspended sediment concentrations at both sites suggest that each site was positioned closed to the estuarine turbidity maximum within its river. Tidal wetland restoration at the head of estuaries may benefit from the large ecological disturbance associated with rapid sediment accretion, providing a productive substrate with little competition from prior vegetation. However ultimate vegetation patterns may take longer to develop as elevation gains alter tidal flooding frequency. Low salinities suggest that the physical disturbance of sediment burying prior vegetation is the main mechanism creating a clean slate for plant recolonization, rather than mortality of terrestrial vegetation due to salt water. The majority of elevation change was due to allochthonous sediment deposition, with belowground processes playing a minor role. The wetlands restored showed substantial net elevation gains in the first years following tidal hydrological restoration, but long-term monitoring is required to track their overall resilience in the face of sea level rise.

Prevention of well clogging during aquifer storage of turbid tile drainage water rich in dissolved organic carbon and nutrients

Well clogging was studied at an aquifer storage transfer and recovery (ASTR) site used to secure freshwater supply for a flower bulb farm. Tile drainage water (TDW) was collected from a 10-ha parcel, stored in a sandy brackish coastal aquifer via well injection in wet periods, and reused during dry periods. This ASTR application has been susceptible to clogging, as the TDW composition largely exceeded most clogging mitigation guidelines. TDW pretreatment by sand filtration did not cause substantial clogging at a smaller ASR site (2 ha) at the same farm. In the current (10 ha) system, sand filtration was substituted by 40-μm disc filters to lower costs (by 10,000–30,000 Euro) and reduce space (by 50–100 m2). This measure treated TDW insufficiently and injection wells rapidly clogged. Chemical, biological, and physical clogging occurred, as observed from elemental, organic carbon, 16S rRNA, and grain-size distribution analyses of the clogging material. Physical clogging by particles was the main cause, based on the strong relation between injected turbidity load and normalized well injectivity. Periodical backflushing of injection wells improved operation, although the disc filters clogged when the turbidity increased (up to 165 NTU) during a severe rainfall event (44 mm in 3 days). Automated periodical backflushing, together with regulating the maximum turbidity (<20 NTU) of the TDW, protected ASTR operation, but reduced the injected TDW volume by ~20–25%. The studied clogging-prevention measures collectively are only viable as an alternative for sand filtration when the injected volume remains sufficient to secure the farmer’s needs for irrigation.

Microplastic Effects on Thrombin-Fibrinogen Clotting Dynamics Measured via Turbidity

Background/Hypothesis:Widespread use of plastic has created a world where exposure to microplastics is inevitable leading to their presence in our circulatory system. This raises questions about microplastics impact on thrombosis. Aminated polystyrene (aPS) plastics have been shown to increase platelet aggregation and thrombus formation in animal models. Given this, we hypothesized that aPS administration will increase the rate of fibrin clot formation in a simple thrombin-fibrinogen clot model.&#x0D; Project Methods:We evaluated how concentrations of 25-200 μg/mL of 100 nm aPS particles affect fibrin clot formation using turbidity assays. To determine the effect of surface charge, experiments were also performed with non-modified polystyrene (nPS) particles. Microplastics were pre-incubated either with physiological concentrations of fibrinogen or thrombin and the clot formation was measured using turbidity at 405 nm every 10 seconds over 45-minutes. Clotting parameters such as maximum turbidity (TurbMax), time to 90% maximum turbidity (TurbTime), and clot formation rate (Vmax) were determined and compared to controls without microplastics.&#x0D; Results:When increasing concentrations of aPS were preincubated with thrombin or fibrinogen, there was less than a 2-fold change in Vmax, TurbMax, and TurbTime. When increasing concentrations of nPS were preincubated with thrombin, there was up to a 27-fold decrease in Vmax, 2.4-fold decrease in TurbMax, and 4.36-fold increase in TurbTime compared to the control. Whereas preincubation of nPS with fibrinogen resulted in 1.86-fold decrease in Vmax, 1.63-fold decrease in TurbMax, and 2.30-fold increase in TurbTime.&#x0D; Potential Impact:In this simplified clotting model, it was surprising to find inhibitory effects on clot formation and that they were more pronounced with nPS than with aPS. However, these results align with increase prothrombin time observed in literature in presence of aPS. Therefore, future studies with more complex clotting models need to be performed before claims can be made on the impact of microplastics on thrombosis.