Load In Water Research Articles

The Anti-Overturning Response of Tripod Bucket Foundation for Offshore Wind Turbines

The tripod bucket jacket foundation is proven to be a practicable solution for offshore wind turbines (OWTs) to withstand huge environmental loads in deep water. This paper presents model tests for a scaled tripod bucket jacket foundation with reference to a prototype applied in China to obtain its lateral load bearing behavior in medium-dense sands. Extended finite element analyses were conducted by ABAQUS to compare anti-overturning responses for the tripod bucket foundation in both sand and soft clay, and the influences of loading direction and aspect ratio were also taken into account. The results showed that the failure modes of the laterally loaded tripod bucket foundation are the pull-out of the windward bucket in sand and the settlement of the leeward bucket in soft clay, respectively. Thus, the unfavorable loading direction of the foundation changes with soil type. It is also shown that the bearing capacity for the foundation in soft clay will be enhanced more effectively as the bucket diameter increases. Instead of the rotational soil resistance resulting from the rotation of the bucket, the vertical soil resistance governs the anti-overturning bearing capacity of a tripod bucket foundation. As the tilt created by the overturning moment rises, the rotational stiffness of the foundation dramatically declines.

Effectiveness of denitrification bioreactors with woodchips, corn stover, and phosphate-sorbing media for simultaneous removal of drainage water N and P in a corn-soybean system.

Millions of acres of farmland in the midwestern United States (US) are artificially drained, and this contributes to the export of nitrogen (N) and phosphorus (P) from agricultural land to surface water. Using a 36-acre tile-drained farm field, effects of P-sorbing media in combination with a denitrifying bioreactor system constructed with woodchips (WC) and corn stover (CS) on reducing nutrient export in drainage water were tested for 3 cropping years (2018-2020). The field was divided into three subfields as replicates. In each subfield, the drainage water was divided and separately channeled into three bioreactors, each of which contains one of the three different substrates: WC, CS, and CS-WC (1:1 v/v mixture of CS and WC), randomly assigned. The outlet of each compartment contained a 2.25L flow-through chamber filled with activated iron (Fe) filings as P-sorbing material. Both WC and CS bioreactors were effective in removing drainage NO3 - with a 77% (WC), 86% (CS), and 89% (CS-WC) reduction in mean NO3 - -N concentration. For the three cropping years, the WC bioreactor reduced the total drainage inorganic N (NO3 - -N+NH4 + -N) load by 72%, but the CS bioreactor increased the total inorganic N load in the drainage water due to the substantial release of NH4 + with the decomposition of CS. The breakdown of CS also increased drainage P. The NH4 + and P release decreased with the decrease in the proportion of CS; thus, not more than 10% of CS is recommended for blending with WC to enhance the performance of a bioreactor. The P-sorbing Fe filing media reduced the P loads in drainage by an average of 19% during the 2-year study.

Escherichia coli POLLUTION IN COASTAL LAGOON AND DAM RESERVOIR: REPERCUSSIONS ON PUBLIC HEALTH AND AQUACULTURE

Escherichia coli are rod-shaped gram-negative bacteria naturally present in the lower intestinal tracts of warm-blooded organisms including humans and are often released into the environment through faecal material and wastewater effluent. The presence of E. coli in waters has long been regarded as an indicator for recent faecal contamination, and possible presence of other more harmful enteropathogens. This study examined the total coliform load and occurrence of E. coli to determine the microbial water quality of Merchang Lagoon on Terengganu coast facing the South China Sea, and Raban Lake, part of the Chenderoh Hydroelectric Dam reservoir in the Lenggong Valley, Perak. Water samples were collected from three sites in the lagoon, and two sites in the lake. Total coliform load in water was enumerated by most probable number (MPN) method, and E. coli isolation was carried out using eosin methylene blue (EMB) agar. The results showed greatly varied total coliform counts from site to site in both the lagoon (site 1: 7; site 2: 220; site 3: 920 CFU/100 mL) and lake (site 1: 220; site 2: 1600 CFU/100 mL). All sites showed presence of E. coli. The results suggest faecal pollution, and the impact of water stagnation and human activities on the coliform load. The impacts of faecal pollution on public health and aquaculture in the investigated areas are discussed. Long-term monitoring of faecal pollution constitutes the essential part of environmental conservation and preservation against the risk of waterborne faecal pathogens in recreational and commercial activities.

Double cross-linked transparent superhydrophilic coating capable of anti-fogging even after abrasion and boiling.

The commercial application of surfaces with superhydrophilic (SHPL) properties is well known as an efficient strategy to address problems such as anti-fogging, anti-frosting, and anti-biological contamination. However, current SHPL coatings are limited by their poor water and abrasion resistances. Thus, herein, to solve these problems active glass was employed as a substrate, and a stable and transparent SHPL solution was prepared via the spraying process. Aqueous polyacrylic resin (PAA), SiO2 nanoparticles (NPs), tetraethyl orthosilicate (TEOS), and sodium allyl sulfonate (SDS) were utilized as the four main components of the PAA-TEOS-SiO2 coating. The durability properties including anti-abrasion, resistance to water, and contact component loss were investigated via the Taber abrasion test, boiling water immersion test, and anti-fogging test, respectively. Furthermore, the structure, composition, and wettability of the coating before and after the friction and water immersion tests were compared via water contact angle (WCA) measurements. Furthermore, the effect of the type of resin on the properties of the coating was investigated. The surface morphology of the blended water-based polyacrylic acid (PAA) resin was uniform and flat and its adhesion to the substrate was the highest (4.21 MPa). Considering the durability and optical properties of the coating, the optimal blend was 3 wt% PAA resin, which exhibited a transmittance of 90%. When the content of TEOS, which enhanced the crosslinking in the coating, was increased to 2 wt%, the results showed that the SHPL coating maintained good anti-friction, boiling resistance, and anti-fogging properties under the conditions of 300 cycle Taber friction with 250 g load and soaking in hot water at 100 °C for 1 h. In particular, the excellent durability of strong acid and alkali resistance, heat resistance, and long-term aging resistance will facilitate the commercial viability and expand the application of SHPL coating in various research fields.

Peel behavior of polyurethane/Monel 400 interface under load in saline water

ABSTRACT This study investigates the coupling effects of saline water and cable weight on the adhesive energy of polyurethane/Monel 400 interface using a dead weight peel test. Cables play a crucial role in naval structures serving as a central nervous system. The cables and their connectors are generally molded, encapsulated, or potted with polyurethanes to ensure that they are insulated and waterproof. During service, exposure of some of these cables and their connectors to the marine environment results in the premature failure of the polyurethane/metal interfaces of connectors. Three sets of experiments were carried out to better understand this phenomenon: an initial 90° fixed arm peel test to determine the strength of the interface, a hanging weight peel test in saline water at an elevated temperature to determine the effects of weight variation and saline water degradation, and a dead weight peel test at varying saline water temperatures to determine the acceleration factor. According to the findings, no peel was recorded in the peel experiments conducted in air indicating that the strength of the interface is higher than that of the peel arm. In the dead weight peel tests, increasing the masses of the hanging weights increased the peel velocity. Additionally, for low peel velocities, a linear relationship was observed between adhesive energy and peel velocity. Furthermore, a more cohesive primer failure was observed at the end of the peel process, indicating that peel velocity increased with longer exposure to saline water.

Effects of soil small strain nonlinearity on dynamic impedance of horizontally loaded suction caisson for offshore wind turbines

Suction caisson foundation is receiving increasing attention for its strong capacity of resisting horizontal and overturning loads in shallow water (0–30 m). Though extensive studies have been carried out on its performance under static loading, limited understanding has been reached on the dynamic properties of suction caisson foundation, especially regarding the effect of soil small strain nonlinearity. In this study, finite element method (FEM) is used to capture the dynamic impedance degradation of a typical suction caisson foundation in South China Sea. A series of parametric studies were performed to analyze the effects of soil nonlinearity and soil profile on the dynamic impedance of the suction caisson. The results show that the dynamic impedance of the suction caisson is significantly affected by the load magnitude and the degree of soil nonlinearity. It also indicates that the horizontal stiffness of the suction caisson is closely related to the soil modulus in relatively shallow strata above the skirt tip, while the horizontal-rocking stiffness and rocking stiffness are closely related to the soil modulus below the bottom of the suction caisson. Finally, simple functions are proposed to capture the effects of soil nonlinearity and soil stiffness profile on the dynamic impedance of suction caisson.

Effect of Commercial Probiotics on Growth Performance of Sabaki tilapia, Oreochromis spilurus

The use of beneficial bacteria to improve fish health and growth is an innovative method in aquaculture practice. A study was conducted to test the efficiency of two commercial probiotics, such as Sanolife Pro-W and Protexin Balance on the microbial load in culture water and growth performance of Sabaki tilapia, Oreochromis spilurus in fiber glass tanks (400 liters) for a period of 75 days. Sanolife was supplied at 3ppm in the rearing water daily, and designated as Treatment 1. Protexin was incorporated at the rate of 1ppm in a supplementary feed, containing 35% protein in diet and considered as treatment 2. A control was also maintained without treating with probiotics in culture water or feed. Healthy and uniform size fish (3.1 ± 0.5g) were stocked at the rate of 25peaces/tank and both treatments and control tanks were set on a randomized design and triplicated. Water quality parameters (physical and chemical), microbial load in water, growth performance and body composition (nutrients) of fish were assessed during the culture period. Significant difference (p<0.01) on growth was observed between control and treatments, the highest growth was recorded in Protexin treated fish. Water quality parameters did not show significant variations. Carcass protein and lipid content showed significant difference between control and treatments. Considerable reduction in bacterial population and improved growth were observed in Sanolife Pro W treated water, when compared to Control. The result shows that Sanolife significantly reduce the bacterial population in culture water and Protexin improves the growth of fish. The outcome of the study has great application in the field of tilapia aquaculture sector in the Kingdom.

Development of TaqMan quantitative PCR assay for detection of Nocardia seriolae in fish and the environment

Nocardia seriolae is a gram-positive bacterium that causes nocardiosis, threatening fish farming. Advanced nocardiosis is challenging to control; thus, accurate detection methods of the causal agent in the early disease stage are required. In this study, we developed a TaqMan fluorescence quantitative PCR (qPCR) assay for quantitative detection of N. seriolae in fish tissues and water samples. A pair of highly specific primers and a TaqMan probe were designed based on the N. seriolae 16S23S rRNA internal transcribed spacer (ITS) region. A high correlation coefficient (R2 = 0.998) of the standard curve with a 99.5% efficiency was obtained. The qPCR detection limit of the method was as low as 19.8 copies/μL, 1000 times more sensitive than conventional PCR, and has a good performance in the detection of cultured bacteria (y = −3.750× + 48.075, R2 = 0.974). Even 1.42 CFU/mL N. seriolae collected from 500 mL of natural pond water can be detected. Furthermore, a linear model for the relationship between the log of bacteria load and Cq values in water was established (y = −3.239× + 40.978), and the R2 value was 0.979. This assay was used for accurate N. seriolae detection in fish tissues, water samples, feeds and soils. This study provides a valuable tool for the early detection and control of nocardiosis in aquaculture.

Effect of Solar Water Disinfection on Microbial Load and Concentration of Bisphenol-A in Rivers State, Nigeria

This research was aimed at determining the efficacy of solar radiation as a good source of reducing microbial load in water and the determination of Bisphenol- A concentration in bottled water and sachet water. The parameters evaluated are: Total bacterial count, Total fungi count, Salmonella Shigella, Coliform, Bisphenol A, pH, Dissolve oxygen, Total dissolve solid, Turbidity, total hardness. The bacteria genera isolated are; Staphylococcus, Pseudomonas sp, Echerichia coli, Klebsiella sp, Salmonella sp, Bacillus sp. Micrococcus sp. Proteus sp. Corynebacterium sp. The fungi genera isolated are Penicillium sp, Aspergillus niger, Mucor sp. Cadida sp. Fusarium sp. These organisms reduce as the number of hours of exposure increases. The Bisphenol A concentration increases as the exposure time increases. The study revealed that solar radiation (sunlight) is a good source of water disinfection. The study however recommends the use of PET Polyethylene Terephthalate bottle in water purification using sunlight since PET bottles contains much less additives than bottles made from Poly Vinyl Chloride (PVC)

Fungal diversity in lake and sea beaches of Italy: Relevance to human health

Fungal diseases correlated to beach sand or water have not yet been demonstrated due to the lack of epidemiological studies. This study aims to illustrate the fungal population in beach sands of the two largest Italian lakes and in sands and waters of Mediterranean coasts of Southern Italy to contribute to the identification and assessment of causes of microbiological pollution that might impair bathers health. A great difference was observed between the two lakes, where the total of colony-forming units (CFU) ranged from 33.3 to 1049.9 CFU/g. For coastal sands, the total CFU ranged from 216.7 to 538.8 CFU/g, and for coastal waters the total ranged from 185 to 368.7 CFU/ml.The survey revealed the prevalence of opportunistic pathogenic moulds, mainly Aspergillus spp. (A. niger and A. fumigatus) and Penicillium spp., both in freshwater and costal bathing sites.Dermatophytes and yeasts were not detected in the freshwater sands while they were found at low load in coastal waters (3.3 CFU/ml) and sands (1.7 CFU/g). Differences were observed between urban and non-urban coastal beaches with regard to isolation of dermatophytes only from one urban beach.The present study reports a great diversity of fungi in sand and water of bathing beaches confirming that the Mediterranean region has a greater variety of fungal species.

Study on the management efficiency of lanthanum/iron co-modified attapulgite on sediment phosphorus load

Attapulgite co-modified by lanthanum-iron (MT-LHMT) was used to study its effectiveness and mechanism in controlling phosphorus release from sediments. MT-LHMT has high adsorption capacity for phosphate and the maximum adsorption capacity of MT-LHMT to phosphate can reach 75.79 mg/g. The mechanism mainly involved electrostatic action, surface precipitation and ligand exchange between MT-LHMT bonded hydroxyl and phosphate to form La–O–P and Fe–O–P inner-sphere complexes. MT-LHMT has excellent adsorption performance in the pH range of 3–8. In addition to HCO3−, CO32− and HA− had a negative effect on the phosphorus removal of MT-LHMT, while NO3−, Cl−, SO42−, K+, Ca2+ and Mg2+ had a positive or no effect on phosphorus removal. MT-LHMT significantly reduced the risk of phosphorus release from overlying water in different dose effects and covering methods, as well as the unstable inactivation of flowing phosphorus, sediment dissolved reactive phosphorus (DRP) and available phosphorus with medium diffusion gradient in thin film in the sediment-water interface (Labile-PDGT). The MT-LHMT capping wrapped with fabric can reduce the risk of nitrogen release from sediment to overlying water more than only MT-LHMT capping. The results of this study showed that the MT-LHMT capping wrapped with fabric has high potential and can be used as an active capping material to manage the nitrogen and phosphorus load in surface water.

Spatial effects of urban green infrastructure on instream water quality assessed by chemical and sensory indicators

Urban green infrastructure has been simulated effectively and economically to reduce volume and pollutants of stormwater runoffs but its spatial effects remain unclear. A snap sampling campaign was carried out for surface water quality in the downtown waterway network of a pilot sponge city (Suzhou) in China, dividing into 7 subwatersheds according to the digital elevation map. In total, 144 sampling points were investigated and measured for chemical quality of surface water while 68 out of the sampling points had a sensory evaluation questionnaire interview for water quality with 321 respondents, in whom the native residents scored a significant spatiality of water quality. The downtown waterway network had phosphorus-limited eutrophic surface water with total nitrogen worse than Class V of the national guidelines. Chemical and sensory evaluation indexes of surface water quality had significant spatial consistency (p < 0.001). All types of green spaces (%) in subwatershed, especially along the urban waterway network (waterfront) and roadside, and in the 100 m riparian buffer zone, significantly influenced nutrient loads in surface water. Findings of the present study suggest that the 100 m riparian buffer zone would be priority areas and the waterfront and roadside should be the highly efficient spots for planning strategy on urban green infrastructure implementation to reduce nutrient loads in surface water and to improve urban landscape aesthetics.

Tracing the oomycete pathogen Saprolegnia parasitica in aquaculture and the environment

Saprolegnia parasitica causes saprolegniosis, a disease responsible for significant economic losses in aquaculture and declines of fish populations in the wild, but the knowledge of its distribution and prevalence in the environment is limited. We developed a fast, sensitive and specific S. parasitica droplet digital PCR (ddPCR) assay and demonstrated its applicability for the detection and quantification of the pathogen in environmental samples: swab DNA collected from the host (trout skin, surface of eggs) and environmental DNA extracted from water. The developed assay was used to assess how abiotic (i.e. physico-chemical parameters of the water) and biotic (health status of the host) factors influence the S. parasitica load in the environment. The pathogen load in water samples was positively correlated with some site-specific abiotic parameters such as electrical conductivity (EC) and calcium, while fluorides were negatively correlated, suggesting that physico-chemical parameters are important for determining S. parasitica load in natural waters. Furthermore, skin swabs of injured trout had significantly higher pathogen load than swabs collected from healthy fish, confirming that S. parasitica is a widespread opportunistic pathogen. Our results provide new insights into various environmental factors that influence the distribution and abundance of S. parasitica.

Study on Nitrogen Loss Rules of Paddy Fields under Different Irrigation and Drainage Modes in Southern China

With the growing problem of agricultural nonpoint source pollution, it is an urgent issue to explore irrigation and drainage modes suitable for rice-growing areas in southern China. Barrel experiments were conducted to study the variation of NH4+-N, NO3−-N and TN concentrations in surface drainage and deep percolation water, as well as the rules of nitrogen runoff losses and leaching losses. Treatments included frequent and shallow irrigation (FSI), drought planting with straw mulching (DPS) and water catching and controlled irrigation (WC-CI). The results showed that the trends of NH4+-N, NO3−-N and TN concentrations in surface drainage were similar, and the N concentration gradually decreased with increasing drainage frequency. The trends of NH4+-N, NO3−-N and TN concentrations in deep percolation water were similar, rising to a peak within 5~7 days after fertilization and then gradually decreasing. NH4+-N loss load was the main form of N loss load in surface drainage and deep percolation water, which accounted for 42.06~89.16%. Compared with FSI, DPS significantly increased surface drainage and N runoff loss loads by 98.67% and 125.86%, respectively, while WC-CI significantly reduced them by 59.21% and 66.38%, respectively. Deep percolation water was reduced by 68.59% and 37.99% for DPS and WC-CI, respectively, and N leaching loss loads were reduced by 74.69% and 43.23%, respectively. Compared with FSI, the total TN loss load was significantly reduced by 76.69% and 43.34% for DPS and WC-CI, respectively, and the pollution control was better for DPS. WC-CI significantly increased rice yield by 7.31%, while DPS decreased by 0.95 % due to long-term water stress. Comprehensively considered, WC-CI has obvious advantages, which can reduce nitrogen loss and maintaining a high yield.

S3.5a Contamination in sand and water of sea, lakes, and river beaches: Risk factor for fungal human disease

S3.5 Environmental exposure - risk for human fungal disease, September 21, 2022, 4:45 PM - 6:15 PMMarine and freshwater bodies, such as rivers and lakes are known as possible niches harboring microbes that may affect human health.These ecosystems have been extensively researched, and even regulated, for the presence of bacterial contamination.Fungal contamination has been less researched and lacks regulation, notwithstanding the recent finding that the antifungal resistant yeast species Candida auris has been isolated from a marine ecosystem.The present lecture will focus on a recent collaborative study, involving 13 countries, spanning from the Atlantic to the Eastern Mediterranean coasts, and including the Italian lakes and the Adriatic, Baltic, and Black Seas. The study explored fungal contamination of sand and water of the sea, lakes, and river beaches in 91 bathing sites, and water of 67 of these.This study considered several fungal parameters: all fungi, several species of the genus Aspergillus and Candida, plus other yeasts, allergenic fungi, Dematiaceous fungi, and dermatophytes. The study took in account four variables that might influence the results of the analytical parameters, such as: (1) coast or inland location, (2) urban and non-urban sites, (3) period of the year, and (4) geographical proximity and type of sediment.A site-blind median was found to be 89 Colony-Forming Units (CFU) of fungi per gram of sand in coastal and inland freshwaters, with variability between 0 and 6400 CFU/g. For freshwater sites, that number was 201.7 CFU/g [0, 6400 CFU/g (P = .01) and for coastal sites was 76.7 CFU/g (0, 3497.5 CFU/g)]. For coastal waters and all waters, the median was 0 CFU/ml (0, 1592 CFU/ml), and for freshwaters 6.7 (0, 310.0) CFU/ml (P <.001). The fungal load in water has to be further corroborated in additional ongoing studies.Some of these will be presented herewith.The lecture will also include, as an example, the data collected at the Israeli Mediterranean coast. This study included a screen of sand and water of six urban beaches, from north to south of the Israeli Mediterranean Coast. Sand samples were extracted by water, and the water wash was cultured and quantitated. Water samples were quantitated as well. The fungi were identified phenotypically, by MALDI-TOF MS system and ITS sequencing. The screen revealed that about 80% of the isolates were molds and about 20% yeasts. The mold species included opportunistic pathogens and potential allergens: Aspergillus fumigatus, Fusarium, Penicillium, and Mucorales species. Yeast isolates included Candida, Cryptococcus and Rhodotorula species. The collaborative study and the example study confirmed the relevance of all variables for some of the fungal parameters. The results suggest that beaches should be monitored for fungi for safer use and better management, and for the benefit of public health.

Elucidating the potential of cellulases isolated from a locally isolated strain (NSF-2) in paper and pulp industry

The potential of enzyme cellulases which are known to all has made it pave its way in the field of present-day biotechnology and bio-based emerging industries. For the purpose of human consumption of enzymes, it makes it even more demanding to perform highly precised purification method. Our study deals with the characterization and applicability of cellulases fabricated by a locally isolated strain (NSF-2). The enzyme was purified using standard purification techniques. The isolated enzyme was observed to be of molecular weight 75KDa Purified enzyme showed the best activity at pH5, 50 °C and 3 % substrate concentration. The gene isolated from cellulase enzyme of about 1.2 Kb was amplified from selected isolate. Salts like SDS, urea, EDTA were perceived to have a regressive effect on enzyme activity while tween 20 and tween 100 were neutral towards enzyme. Hg2+ was found to be the most potent inhibitor and Ca2+ was found to be the most potent inhibitor and most significant activator of the enzyme respectively. The waste paper was deinked with isolated enzyme, sodium silicate (5 %) and NaOH (2 %). Various techniques like FTIR, SEM, fluorescence micrographs and fluorescence spectroscopy were performed to study the quality of the deinked paper. The results obtained for cellulase deinking were comparable to sodium silicate treatment but better as compared to NaOH treated paper. Although, the results of enzymatic deinking were similar to the results obtained in sodium silicate treatment but the enzymatic technology proved to be an advantageous technology as compared to chemical deinking as a reduction in dewatering step, declined chemical load in waste water, save capital cost and less energy consumption. The enzyme was found to be highly suitable for application in deinking industries which are in accordance with the observations.

A case study on small-size microplastics in water and snails in an urban river

Microplastic pollution has become pervasive in aquatic ecosystems. They readily interact with aquatic biota, potentially subjecting them to ecological and health risks. Urban rivers are also affected by microplastics due to intense anthropogenic activity. Nevertheless, relatively little is known about the physiocochemistry or ecotoxicology of microplastics in urban rivers. The present study used laser direct infrared chemical imaging to investigate microplastic pollution in a highly urbanized river in Beijing, China. Surface water was sampled at five sites along the river in March and July, and the benthic snail Bellamya aeruginosa was also collected at each location in July. Thirteen and fifteen different polymers were detected and identified in the surface water sampled in March and July, respectively. Thirteen different polymers were found and isolated in the snails. Of these, polypropylene, polyamide and polyethylene predominated in the microplastic particles. Moreover, the average abundance of the microplastic was significantly higher in the surface water sampled in July (39.55 ± 4.78 particles L−1) than in March (22.00 ± 4.87 particles L−1) (p < 0.05). The average microplastic abundance of snails across all sites was 28.13 ± 4.18 particles, among which the Q2 site has significantly higher microplastic abundance than station Q3-Q5 (p < 0.05). Microplastic particles 10–100 μm in size predominated in both the surface water and the snails. By contrast, the proportions of microplastic particles 200–500 μm in size were substantially smaller. The measured microplastic pollution load and microplastic pollution risk indices in the surface water indicated that the current microplastic pollution level in the Qing River was moderate from upstream to downstream. Moreover, the potential adverse effects of microplastic particles on snails remain unclear. Further research is required to elucidate small-size microplastics' environmental fate and potential ecological risks in urban rivers.

Microplastic load in the surface water and Tilapia sparrmanii (Smith, 1840) of the river systems of Okavango Delta, Botswana.

Microplastics are 'emerging' contaminants that threatens freshwaters and may have negative impact on the aquatic organisms. However, Botswana has no information on the status of microplastics, including freshwater like the Okavango Delta- the largest, inland wetland hosting wildlife, tourism, and supporting the socio-economic lifestyle of inhabitants. This study assessed the spatial distribution and characterization of microplastics in surface water and in the digestive organs of fish (Tilapia sparrmanii) from the Okavango delta. Surface water samples (156) and whole intact fish (15) were collected and analysed for microplastic contents by wet peroxide oxidation, potassium hydroxide (fish only), density separation, extraction, and stereomicroscope identification. The weight of microplastics for surface water samples varied from 138.18 to 381.67µgm-3 and abundance ranged from 10.18 to 22.67 items L-1 with significant difference observed between sites in both variables. In tilapia, the highest microplastic abundance were found in the intestines then the stomach and the gills from the fish samples. Most prevailing size ranges of microplastics in fish and water samples were 1-2mm and 2-3mm while the most abundant shapes were fragments and fibres, respectively. Translucent microplastics were dominant in all samples. The results indicate the presence of microplastics in the Okavango delta even though they are very low (µg m-3). This baseline information will provide insights on the loads of microplastics in surface water and the quantities ingested by fish in the Okavango delta hence the need for monitoring. It would also guide on the need for effective policies addressing plastic and microplastic pollution.

Water Quality and Heavy Metal Load in Water and Sediments of Behlol Nullah, a Tributary of River Tawi, Jammu (J &amp; K), India

Behlol nullah is an important tributary of river Tawi and its water quality is the major cause of concern because it receives untreated sewage as well as industrial waste from Gangyal and Bari Brahamana industrial complexes. A current effort is underway to examine the water quality and heavy metal load in the water and sediments. With various anthropogenic activities in mind, this water body has been divided into three stations namely Station-I, Station II and Station III, where Station I receives industrial effluents directly from Gangyal industrial area through Gadigarh nullah, Station II is situated downstream about 400 metres away from the site where industrial waste is directly drained into the nullah and station III is located at chatha around 6.6 kilometres away from station II and this station is devoid of any anthropogenic impacts. Standard procedures were used to analyse physicochemical parameters such as air temperature, water temperature, pH, DO, FCO2, Carbonates, Bicarbonates, Chlorides, Calcium, Magnesium, BOD, Nitrates, Phosphates and Sulphates in both water and sediments. Based on WQI score, the results of this investigation revealed variances in water quality. AAS was used to assess the level of pollution in the water and sediments of Behlol nullah for the heavy metals Fe, Cu, Zn and Pb. Heavy metal concentrations in sediments were found to be greater than in water, with the sequence of Fe&gt;Zn&gt;Cu&gt;Pb in water and Fe&gt;Cu&gt;Zn&gt;Pb in sediments. However, Fe was found to be highest in both water and sediments at all the study sites, and some heavy metal concentrations was found to be beyond the WHO- recommended tolerable level, indicating that this water body needs immediate attention.

Water quality and potamoplankton periodicity of Sitalakhsya river, Narayanganj, Bangladesh

The section of Sitalakhsya River near heavily industrial zone of the District of Narayanganj has been studied for its water quality and potamoplankton dynamics. One year bimonthly sampling from DakhshinRupshi Station of the river was carried out. The air and water temperature of the river ranged from 25.6 - 34.0°C and 26.5 - 32.8°C, respectively. The temperature of water was lower than air by ca. 2.0°C. Water depth at the study station did not vary much but fluctuated only between 6.09 and 7.92 m. The Secchi disc transparency (Zs) varied from 0.2 - 0.6 m showing the lowest in March. Total dissolved Solids (TDS) load in water was 85 - 663 mg/l but the electrical conductivity varied from 110 - 910 μS/cm being the month of March as highest record. pH was alkaline and the fluctuations were negligible (7.2 - 7.4). Alkalinity peaked in March (6.65 meq/l) which dropped to 1.00 meq/l in August and October. Both dissolved oxygen (DO) and free carbon dioxide levels were low which varied from 0.37 - 2.43 and 0.04 - 1.93 mg/l, respectively. Among dissolved nutrients, soluble reactive phosphorus (SRP) showed a low value from May to December (89.48 - 127.70 μg/l). It, however, peaked during March (1265.94 μg/l). Soluble reactive silicate (SRS) concentration ranged from 7.01 - 82.11 mg/l, while the concentration of NO3-N ranged from 0.19 - 1.29 mg/l. The potamoplankton biomass as chl-a ranged from 3.38 - 24.52 μg/l, while its degraded product phaeopigment varied from 1.97 - 11.13 μg/l. The total density of potamoplankton showed their highest growth during December to March (2223 - 4293 ×103) and the lowest from May to October (181 - 785 ×103). The ranges of water quality and planktonic parameters recorded from the Sitalakhsya River are quite comparable with three other peripheral rivers of Dhaka Metropolitan City (DMC) namely, Balu, Turag, and Buriganga. But, low DO and poor transparency along with higher load of TDS made this river water quality relatively lower grading compared to others. Dhaka Univ. J. Biol. Sci. 30(3 CSI): 487-497, 2022 (June)