rss_2.0Chemistry FeedSciendo RSS Feed for Chemistryhttps://www.sciendo.com/subject/CHhttps://www.sciendo.comChemistry Feedhttps://www.sciendo.com/subjectImages/Chemistery.jpg700700Colloidal matter separation of industrial wastewaters from Galați City area by semipermeable membraneshttps://sciendo.com/article/10.2478/auoc-2022-0008<abstract> <title style='display:none'>Abstract</title> <p>Various studies have shown that ultrafiltration membranes are successfully involved in the removal process of most organic pollutants from wastewater. In this context, the hydrodynamic characteristics of a modified cellulose ultrafiltration membrane were evaluated. This composite membrane type has been proposed for the separation of colloidal matter from industrial wastewater in Galati City area (Romania). Another purpose of this paper was also to determine the volume flows, along with the permeate and concentrate fluxes through the technical membrane taken under study. Furthermore, a comparative analysis of three samples of industrial water from Galați City area in terms of the degree of contamination was performed. Surface modification was evaluated using scanning electron microscopy. Results indicated that the industrial wastewater from the steel factory Liberty Galati was significantly more impure than the water from Cătuşa Lake, which in turn was more impure than the water from Siret River, as indicated by comparative analysis of the water samples subjected to the ultrafiltration operation through semipermeable technical membranes. It was shown that the decrease of the permeate flux at the modified cellulosic membrane was accentuated in the first moments, probably due to the clogging of the surface pores that present an uneven distribution. The results of the present study show that the cellulosic membrane used has pore diameters which correspond to the values recommended for the retention of colloidal matter.</p> </abstract>ARTICLE2022-05-17T00:00:00.000+00:00Catalytic pyrolysis of low density polyethylene and polypropylene wastes to fuel oils by N-clayhttps://sciendo.com/article/10.2478/auoc-2022-0007<abstract> <title style='display:none'>Abstract</title> <p>Dealing effectively with plastic wastes has been a major global challenge. Different methods have been previously employed to proffer solution to plastic wastes problem however, all showed their energetic, economic and environmental implications. In this research, catalytic pyrolysis of low density polyethylene and polypropylene wastes was carried out to proffer solution to the problem. The plastic materials were collected and appropriately prepared after which ultimate and proximate analysis was carried out on them. The clay was collected from Naka, Gwer West Local Government Area of Benue State, Nigeria, thereafter, referred to as N-clay and was appropriately prepared, then analyzed by a BET analyzer for the following properties: the surface area, which was found to be 85.418 m<sup>2</sup>/g, pore size 2.100 nm and pore volume of 0.042 cc/g. Also, the XRF determination of the chemical composition of the N-clay was done and the SiO<sub>2</sub>/Al<sub>2</sub>O<sub>3</sub> ratio was found to be 70.81/29.19. The N-clay and the plastics were then pyrolyzed in a chemical vapor deposition (CVD) reactor in the ratio 1:3 respectively, at 500 <sup>o</sup>C with residence time of 30 min using nitrogen as purge gas. The polypropylene yielded 70.34 % liquid oil, 6.43 % char and 23.23 % gas. The liquid was analyzed for functional groups, using Raman spectrometer. Physicochemical analysis was also done on the oil and it was determined that the oil had properties consistent with commercial-grade gasoline. The low density polyethylene yielded wax, instead of liquid, char and gas. Finally, it was concluded that the N-clay was suitable as catalyst for the pyrolysis of plastics and the fuel oil obtained from polypropylene pyrolysis is comparable to gasoline fuel.</p> </abstract>ARTICLE2022-05-17T00:00:00.000+00:00Entropy generation analysis in a gasket plate heat exchanger using non-spherical shape of alumina boehmite nanoparticleshttps://sciendo.com/article/10.2478/auoc-2022-0006<abstract> <title style='display:none'>Abstract</title> <p>The analysis deals with the thermo-hydraulic performance of a Gasket Plate Heat Exchanger used for cooling vegetable oils with a water-ethylene glycol 50% and volume fractions of non-spherical nanoparticles mixture as a refrigerant. The heat exchanger has 75 plates with a chevron angle equal to 30º. The Reynolds number of the refrigerant varies from 80 to 1530. The Reynolds number of the sunflower vegetable oil is fixed and equal to 30. The non-spherical nanoparticles used for analysis are platelet, cylindrical and brick types. Graphical results are presented for global heat transfer coefficient, heat capacity ratio, heat transfer rate, outlet temperatures, thermal and viscous entropy generation rate, and Bejan thermodynamic number. The results obtained allow us to conclude that it is possible to work with low relative flow rates using non-spherical nanoparticles, emphasizing platelet nanoparticles. The entropy generations analysis shows that very high flow rates of the refrigerant dissipate much of the energy in viscous form and do not contribute to oil cooling, with a consequent increase in the heat exchanger operating costs.</p> </abstract>ARTICLE2022-05-17T00:00:00.000+00:00Mechanical characteristics of Biomaterial Particles Reinforced Epoxy Resin Composites for Automobile Accessorieshttps://sciendo.com/article/10.2478/ast-2022-0002<abstract> <title style='display:none'>Abstract</title> <p>In this study, rattan corncob composite materials were developed and their mechanical properties were determined. This was with a view to producing alternative composite materials for automobile applications. Dried corncobs and rattan cane were crushed, treated with caustic alkali NaOH <sub>(aq)</sub> and transferred into a water bath machine to reduce the hydrophilic nature of the fibres in the polymer. The shredded corncobs and rattans cane were sun-dried after the treatment to remove the moisture content and were further pulverized and sieved to obtain 400μm particle size. Compositions of the particles were varied for seven samples with the binder kept constant at 80wt% of the whole mixture and forming them into particle panels using a metal mould. The process was repeated in order to obtain three replicates to get the exact mean value. The produced panels were tested for density, water absorption, tensile strength and modulus, flexural strength and modulus, and optical microstructure. The results revealed that the densities ranged between 1.06g/cm<sup>3</sup> to 1.30g/cm<sup>3</sup>, the water absorption properties ranged between 0.87% to 4.55%, tensile strength ranged between 42MPa to 90MPa, tensile modulus ranged between 2.2GPa to 5.9GPa, flexural strength ranged between 50MPa to 70MPa and flexural modulus ranged between 1.5GPa to 2.7GPa. It was concluded that the developed composite materials have good mechanical properties and could serve as alternative materials for making automobile accessories like bumpers and spoilers. It could also help in solving the problem of environmental pollution caused by open burning.</p> </abstract>ARTICLE2022-05-16T00:00:00.000+00:00Nanotextiles — materials suitable for respiratory tract protection but a source of nano- and microplastic particles in the environmenthttps://sciendo.com/article/10.2478/acs-2022-0006<abstract> <title style='display:none'>Abstract</title> <p>The paper deals with the formation of nanomaterials (nanoparticles and nanofibers) in the manufacture and use of respiratory protective equipment. It focuses mainly on processes leading to the release of nanoplastics into the workplace and the environment. Based on selected properties of materials used for the manufacture of protective equipment, their stability in the environment is revealed. The paper demonstrates the impact on the environment considering semichronic phytotoxicity of nanoplastics.</p> </abstract>ARTICLE2022-05-16T00:00:00.000+00:00Thermochemistry of antioxidant action of isoflavones and their deprotonated forms in aqueous solution: hydrogen or electron transfer?https://sciendo.com/article/10.2478/acs-2022-0004<abstract> <title style='display:none'>Abstract</title> <p>Isoflavones possessing several weak acidic hydroxyl groups can undergo successive deprotonations in aqueous solutions. Therefore, their antioxidant properties cannot be ascribed only to the neutral forms but also to corresponding phenoxide anions. It was already confirmed that isoflavones prefer the formation of dianions in aqueous solution. For eight isoflavones and their preferred (poly)deprotonated forms, thermochemistry of hydrogen atom transfer and electron abstraction was studied in terms of corresponding reaction enthalpies, i.e., O—H bond dissociation enthalpies and ionization potentials. Our results clearly indicate that the increase in negative charge causes significant drop in ionization potential and bond dissociation enthalpy. On the other hand, proton affinities show the opposite trend. Thus, it is unfeasible to find a generally valid trend for dianions — corresponding reaction enthalpies strongly depend on the structure of isoflavone, especially on the number/positions of OH groups.</p> </abstract>ARTICLE2022-05-16T00:00:00.000+00:00Pre-treatment of lignocellulosic materials by enzymatic mixture to enhance biogas productionhttps://sciendo.com/article/10.2478/acs-2022-0005<abstract> <title style='display:none'>Abstract</title> <p>The aim of this study was to evaluate the effect of an enzymatic mixture on the increase of biogas production from lignocellulosic materials as rapeseed straw, maize waste, and wheat straw. For efficient application of the enzymatic mixture, conditions of its use were optimized regarding 50 °C, pH 7 and an enzyme dose of 0.25 % w/v. Biogas potential test confirmed positive effect of the enzymatic mixture on anaerobic digestion of already thermally and alkali pre-treated lignocellulosic materials, as significantly higher biogas production was observed after the enzymatic mixture addition for all monitored substrates. Addition of the enzymatic mixture to the most used substrate at biogas plants — maize silage, had also positive effect on biogas production during the biogas potential test. This fact was not proven during long-term operations of the reactors as the values of total cumulative biogas productions for the whole monitored period from reactors for anaerobic digestion of maize silage with and without addition of enzymatic mixture did not differ significantly.</p> </abstract>ARTICLE2022-05-16T00:00:00.000+00:00An Evaluation of a Language Processor for an African Native Languagebased Programming Languagehttps://sciendo.com/article/10.2478/ast-2022-0001<abstract> <title style='display:none'>Abstract</title> <p>The design and prototype implementation of a subset of an African indigenous language-based programming language has been carried out and reported. In this study, an evaluation of the processor developed for the native language-based programming language was carried out in order to assess its level of conformance to the characteristics required of a good software product as set by the international organization for standardization (ISO). The developed language processor was evaluated using some metrics for evaluating the quality of software systems including structural and time complexity. A usability test was also conducted to assess users’ perception of the system concerning its relevance and ease of use. The result of system evaluation indicated that the system contains 1558 lines of code, its cyclomatic complexity is 14 and its asymptotic time complexity is of order big oh O (n<sup>3</sup>), where n is the size of the input to the system. Over 86% of the participants in the usability test attested to the system’s relevance while the usability rating was 86%. The developed system can be inferred to be of good quality as the results of its evaluation are positively on the high side for satisfying most of the ISO criteria for adjudging a software product as being of good quality. Furthermore, the high usability rating for the system indicates that the programming language whose compiler was evaluated satisfies most of the criteria set by the Department of Defense (DOD) for assessing the ‘goodness’ or otherwise of a programming language.</p> </abstract>ARTICLE2022-05-06T00:00:00.000+00:00Effects of morphometric and biochemical parameters on collagen and pepsin-solubilized collagen yields of (Gmelin, 1790) and () (Delle Chiaje, 1823)https://sciendo.com/article/10.26881/oahs.2022.1.09<abstract><title style='display:none'>Abstract</title><p>Due to their unique biochemical composition, sea cucumbers are highly prized marine echinoderm species. One of their most important properties is that they contain a high amount of collagen in their body wall. In this study, the relationship between collagen and pepsin-solubilized collagen yields from <italic>Holothuria tubulosa</italic> and <italic>Holothuria poli</italic> and morphometric and biochemical parameters were investigated.</p><p>Collagen yields were in the range of 10.63–16.04% for <italic>H. tubulosa</italic> and 7.12–13.10% for <italic>H. poli</italic>. It was determined that they may be related to length, body wall weight, and biochemical composition at different length frequencies. Moreover, maturity may have a direct effect on the yield, as mature specimens were found to have lower content of collagen, whereas immature small specimens contained a higher percentage of collagen. It was found that with increasing pepsin concentration, the PSC yield increased to 1.83–1.89% in <italic>H. tubulosa</italic> and <italic>H. poli</italic>, respectively. It was determined that collagen from smaller individuals, which contained more moisture and ash, was likely more susceptible to pepsin hydrolyzation.</p><p>This is the first published study demonstrating that collagen yield of sea cucumbers can vary with length, weight, maturity, and biochemical composition, in addition to species-specific differences.</p></abstract>ARTICLE2022-03-31T00:00:00.000+00:00Parasites of the invasive Chinese sleeper (Actinopterygii: Odontobutidae) in the region of the first introduction of the Carpathian populationhttps://sciendo.com/article/10.26881/oahs.2022.1.01<abstract><title style='display:none'>Abstract</title><p>Parasites of the invasive Chinese sleeper (<italic>Perccottus glenii</italic>) were studied in five different localities at the site of the first introduction of the Carpathian population of this fish. We recorded eight taxa of parasites in Lviv water bodies. The monogenean <italic>Gyrodactylus perccotti</italic> and the cestode <italic>Nippoteania perccotti</italic> were recorded in all five lakes studied. These parasites represent Far East species introduced together with their host. Also the copepod <italic>Neoergasilus japonicus</italic> is a Far East parasite introduced to Europe with its aquaculture vector. Differences between the surveyed bodies of water were mainly related to their local seasonal conditions and watershed characteristics. The current data confirm the presence of co-introduced populations of <italic>G. perccotti</italic> and <italic>N. perccotti</italic>, which probably affects the future invasiveness of their host. Due to low acquisition of local parasites, we cannot confirm any significant effect of invasive fish on local parasite assemblages in this region. However, the presence of the non-indigenous copepod, <italic>N. japonicus</italic>, requires additional attention in the future.</p></abstract>ARTICLE2022-03-31T00:00:00.000+00:00Assessment of inorganic nitrogen and phosphorus compounds removal efficiency from different types of wastewater using microalgae cultureshttps://sciendo.com/article/10.26881/oahs.2022.1.05<abstract><title style='display:none'>Abstract</title><p>The efficiency of ammonium nitrogen (N-NH<sub>4</sub><sup>+</sup>) and phosphate (P-PO<sub>4</sub><sup>3−</sup>) removal from wastewater with different loads of these nutrients was evaluated using <italic>Chlamydomonas reinhardtii</italic> (Chlorophyta) and <italic>Oscillatoria neglecta</italic> (Cyanophyta/Cyanoprokaryota). In addition, functional characteristics of the microalgae under the studied conditions were determined. It was demonstrated that <italic>Ch. reinhardtii</italic> is resistant to a wide range of concentrations of inorganic nitrogen and phosphorus compounds. Microalgae actively participate in the removal of N-NH<sub>4</sub><sup>+</sup> from wastewater (removal efficiency of 49–63%, depending on the initial concentration). At the same time, <italic>Ch. reinhardtii</italic> showed low levels of P-PO<sub>4</sub><sup>3−</sup> removal (7–18%) from the aquatic environment. <italic>O. neglecta</italic>, unlike <italic>Ch. reinhardtii</italic>, is sensitive to excessively high concentrations of N-NH<sub>4</sub><sup>+</sup> (90–140 mg l<sup>−1</sup>) and P-PO<sub>4</sub><sup>3−</sup> (26–90 mg l<sup>−1</sup>). However, it is characterized by high removal efficiency for both forms of nitrogen (60–61%) and phosphorus (43–55%) at their initial concentrations of 30–50 mg l<sup>−1</sup> and 7–14 mg l<sup>−1</sup>, respectively. Therefore, <italic>O. neglecta</italic> is best suited for use in wastewater post-treatment.</p></abstract>ARTICLE2022-03-31T00:00:00.000+00:00Molecular identification and distribution of insect larvae in the Lower Danube Riverhttps://sciendo.com/article/10.26881/oahs.2022.1.07<abstract><title style='display:none'>Abstract</title><p>As a major component of freshwater ecosystems, insect species play an important role in nutrient cycling and are often used as bioindicators of water pollution. Although extensive studies have characterized insects from freshwater habitats, little is known about the distribution of these species along the Lower Sector of the Danube River. Therefore, this survey conducted in the Danube section within the Romanian territory aimed to identify insect larvae belonging to seven different species of Odonata, Trichoptera, Ephemeroptera, Lepidoptera and Megaloptera by DNA barcoding and to investigate their distribution, density and frequency. A total of 41 quantitative macrozoobenthic samples were collected during two consecutive years (2019 and 2020). Species showed large differences in the distribution and density along different sections, and an overall tendency to populate downstream areas, except for <italic>Sialis morio</italic>. On the other hand, only <italic>Hydropsyche bulgaromanorum</italic>, <italic>Triaenodes bicolor</italic> and <italic>S. morio</italic> larvae were identified in the upstream section (Sulina branch). These data provide baseline information on the larger range of some of the most common aquatic insects in the Romanian Danube section in relation to several environmental parameters based on the first molecular identification of these species using COI gene sequencing.</p></abstract>ARTICLE2022-03-31T00:00:00.000+00:00Life history of wahoo, , in the Tropical Eastern Atlantic Ocean – the importance of applying a suite of methods for fisheries assessment in data-limited situationshttps://sciendo.com/article/10.26881/oahs.2022.1.10<abstract><title style='display:none'>Abstract</title><p>Unassessed fisheries, mostly non-targeted fisheries, are now particularly predominant in many commercial fisheries and are critical to food security in developing countries. These fisheries typically lack reliable data essential for assessing their stocks, leaving them susceptible to overfishing and declining yield over time. This study proposes a framework for determining the life history and management of such fisheries. Data on the length composition and reproduction of wahoo <italic>Acanthocybium solandri</italic>, a common bycatch species in commercial fisheries, were obtained from observers aboard Chinese longline vessels in the Eastern Atlantic between 2010 and 2020 and were used as a case study. A comprehensive methodological approach was applied using data on this species to estimate its life history parameters, to evaluate biological reference points, and to provide proxies for the stock status. The final main growth parameters obtained were: L<sub>inf</sub> = 161.21 cm FL (157.34–194.68), <italic>K</italic> = 0.47/year (0.14–0.65); estimated size at first maturity was 89.6 cm FL. As assessed by the set of methods applied, the wahoo stock state was healthy in the Tropical Eastern Atlantic Ocean. This study advises against using a single approach to determining life history parameters in data-limited fisheries, as this may affect reference points and thus management recommendations. This study provides a route whereby many easy-to-apply methods can be used to understand the status of multiple stocks in poorly managed fisheries, and thus provide management plans.</p></abstract>ARTICLE2022-03-31T00:00:00.000+00:00Sustainability or fun? Recreational angling in Marine Protected Areashttps://sciendo.com/article/10.26881/oahs.2022.1.04<abstract><title style='display:none'>Abstract</title><p>Gökova Bay MPAs (southern Aegean Sea, Turkey) include six different no-take zones (NTZs: Akyaka, Çamlı, Akbük, Boncuk-Karaca, İngiliz Limanı, Bördübet), in four of which shore angling is permitted (Akyaka, Çamlı, Akbük, Boncuk-Karaca). This study determined the total catch and size of fish caught in the Akyaka MPA during recreational fishing. In total, fish representing 22 species belonging to 10 families were caught and most of them were smaller than their length at first maturity. The projection showed that the total catch weight reached significant values for recreational angling in the Akyaka MPA. The results of this study indicate that recreational angling may pose a threat to both MPAs and no-take zones, causing them to deviate from their primary conservation goal due to the harvesting of juveniles by recreational anglers.</p></abstract>ARTICLE2022-03-31T00:00:00.000+00:00Prospects and opportunities for mussel farming in the southern Baltic Sea (the Gulf of Gdańsk)https://sciendo.com/article/10.26881/oahs.2022.1.06<abstract><title style='display:none'>Abstract</title><p>In the Baltic Sea, where osmotic stress limits the growth of marine organisms, mariculture is driven primarily by the need to improve the status of the environment. To this end, several mussel farms have been attempted in selected areas, except the southern Baltic. The pilot culture of <italic>Mytilus trossulus</italic> was carried out with the use of a modified long-line system in the Gulf of Gdańsk in 2009–2012, providing the first evaluation of the mussel farming potential in this area. The growth rate of mussels (3.0–6.7 mm year<sup>−1</sup>) in the gulf was in the low range, but the mean wet biomass gain (1.50 kg m<sup>−1</sup> normalized culture rope) was among the highest in the Baltic. After a two-year growth period, one tonne of mussels fixed in their soft tissues from 93 to 98 kg N t<sup>−1</sup> and 11 kg P t<sup>−1</sup>. The cost-benefit analysis revealed a negative budget balance of production for human consumption, with a total income covering only 12.0% of the cumulative costs. Mussel farming in the gulf can therefore only be justified to improve the environmental quality if additional funding mechanisms are put in place to support farming activity.</p></abstract>ARTICLE2022-03-31T00:00:00.000+00:00Diversity and succession of microbial communities on typical microplastics in Xincun Bay, a long-term mariculture tropical lagoonhttps://sciendo.com/article/10.26881/oahs.2022.1.02<abstract><title style='display:none'>Abstract</title><p>In this study, three polymer types of microplastics (MPs), polyethylene (PE), polystyrene (PS) and polypropylene (PP), were exposed for 60 days in Xincun Bay (Hainan, China), a long-term mariculture tropical lagoon. High-throughput sequencing and scanning electron microscopy (SEM) were used to investigate the succession of microbial community structure and function on MPs after 10, 30, and 60 days of exposure, respectively. The results showed that diversity indices for bacteria from MPs were higher than those for bacteria from seawater. Significant differences were observed in community structure and metabolic function between MPs and seawater. The microbial network structure on MPs was more complex and dispersed than that in seawater. No significant differences in bacterial community structure and metabolic function were observed among different types of MPs. The biofilm on PS was the thickest, and the network structure on PP was the most complex one. With increasing exposure time, the biofilm attached to the surface of MPs became thicker and microbial composition showed some differences. The analysis of potential degradation bacteria and pathogens with abundance above 0.01% showed that the abundance of several potential plastic biodegraders on MPs was higher than that in seawater, while no potential pathogen was found enriched on MPs.</p></abstract>ARTICLE2022-03-31T00:00:00.000+00:00Effects of fishing and environmental parameters on the commercial bony fish assemblage in the southern Caspian Seahttps://sciendo.com/article/10.26881/oahs.2022.1.08<abstract><title style='display:none'>Abstract</title><p>Since the 1990s, anthropogenic activities have been the major direct or indirect threats to the structural and functional organization of the unique ecosystem of the Caspian Sea (CS). This study attempts to investigate the relationships between fish community structure and environmental parameters and to analyze the Abundance Biomass Comparison (ABC) in the CS. The input data, including catch data by species and environmental parameters, were collected from 1996 to 2017. Of the 13 bony fish species identified, only two species <italic>Rutilus kutum</italic> and <italic>Chelon aurata</italic> accounted for 47.14% and 62.65%, and 40.80% and 29.34% of CPUE and NPUE, respectively. DisTLM revealed that five environmental variables showed a significant linear relationship with the NPUE resemblance matrix. Based on the AIC criteria, the combination of year, precipitation, SST_Apr, SSL, SST, GTA, Iranian rivers, and Volga discharges explain 80.3% of the total variability. Based on the ABC curves and W statistics, it was concluded that the fish assemblage was environmentally stressed from 1996 to 2003. The Shannon diversity index (H′) showed a decreasing trend, suggesting that fish species have been exposed to increasing stress over the past 22 years. Considering the current environmental conditions (downward trend in SSL river discharge and increase in SST) and anthropogenic activities, it appears that the downward trend will continue in the future.</p></abstract>ARTICLE2022-03-31T00:00:00.000+00:00 gen. nov. & comb. nov. (Bacillariophyta) – a pantropical marine member of Cocconeidaceaehttps://sciendo.com/article/10.26881/oahs.2022.1.03<abstract><title style='display:none'>Abstract</title><p><italic>Cocconeis dapalistriata</italic>, first described as a member of the genus <italic>Cocconeis</italic>, is re-examined due to its unique ultrastructure. Both valvocopulae of this taxon show significant differences compared to those found in the genus <italic>Cocconeis</italic>. They are expanded and show some similarities with those found in <italic>Amphicocconeis</italic>. On the other hand, terminal parts of the raphe valve (RV) in <italic>C. dapalistriata</italic> are simple and the raphe valve (RV) striae are composed of small round areolae with a hymenate occlusion with radial slits, similar to those observed in <italic>Cocconeis</italic>. <italic>Campyloneis</italic> and <italic>Xenococconeis</italic> also have expanded valvocopulae but with numerous morphological differences compared to those found in <italic>C. dapalistriata</italic>. Furthermore, the areolae of the sternum valve (SV) in <italic>C. dapalistriata</italic> are occluded by a concave velum with no apparent internal slits, and externally ornamented with irregular silica crystals. <italic>Upsilococconeis</italic> Riaux-Gobin, Witkowski &amp; Risjani gen. nov. is proposed to accommodate the latter taxon. First described from the Western Indian Ocean (Mascarenes), it was subsequently listed from the Western Pacific Ocean (Guam), the South Pacific Ocean (French Polynesia and New Caledonia) and from the Eastern Indian Ocean (Indonesia), and thus may qualify as pantropical.</p></abstract>ARTICLE2022-03-31T00:00:00.000+00:00Water Quality and Zooplankton Assessment of Iyiakwu River, Southeast Nigeriahttps://sciendo.com/article/10.2478/eko-2022-0002<abstract> <title style='display:none'>Abstract</title> <p>Water quality and zooplankton assessment of a rural river in Southeast Nigeria was carried out between May 2019 and October 2019 in three stations in relation to anthropogenic activities. The major anthropogenic activity in the river was indiscriminate sand mining. The water samples were collected and analyzed using standard sampling and analytical procedures while zooplankton samples were collected using filtration method. pH and dissolved oxygen values were lower than acceptable limits while some of the biochemical oxygen demand values exceeded the acceptable limit. A total of 447 individuals from 25 zooplankton taxa and three major taxonomic groups were recorded. Copepoda was the dominant group (158 individuals/L), followed by Rotifera (147 individuals/L) and Cladocera (142 individuals/L). Spatially, station 1 had the highest abundance (159 individuals/L), followed by station 3 (152 individuals/L) and station 2 (136 individuals/L). The biodiversity indices (Shannon–Weiner and Margalef) were low while Evenness was high when compared with their respective ranges. This study has shown that the combined effects of season, sand mining and other activities have not adversely affected the water quality and zooplankton community. However, the community structure of the zooplankton groups gave an indication of a moderately polluted environment; attributable to the effects of season and human activities in the watershed. Sand mining is a major activity in the river and needs to be regulated to forestall any adverse effect on the water quality and biota in future as observed elsewhere.</p> </abstract>ARTICLE2022-04-22T00:00:00.000+00:00Soil Fauna of Ranibari Community Forest, Kathmandu, Nepalhttps://sciendo.com/article/10.2478/eko-2022-0003<abstract> <title style='display:none'>Abstract</title> <p>Ranibari Community Forest (RCF) is the important forest patch present within the highly urbanized Kathmandu Valley with information gaps on soil fauna. This study aimed to explore the soil meso and macrofauna of the forest. Fourteen random quadrats (1 × 1 m<sup>2</sup>) were laid within seven blocks. Leaf litter samples and soil cores were collected, screened, sieved, and searched under a white sheet, once a fortnight from May to November 2019. The results showed that the diversity, abundance, and richness of soil fauna were the highest in the summer season (H<italic>´</italic> = 2.897, abundance = 1,973, S = 84) dominated by Collembola. The Soil Biological Quality Index (QBS-ar) value was also found to be the highest in summer (QBS-ar = 417) and successively decreased in succeeding seasons. Soil fauna was diverse and evenly distributed in soil layers throughout the seasons, but the abundance was greater in leaf litters, particularly in summer. Fauna like Chilopoda, Diplopoda, Haplotaxida, and Isopoda were seen to be affected negatively by soil temperature in summer and autumn seasons. Soil moisture content was found to be positively correlated with immature insects, earthworms, and millipedes in the rainy and autumn seasons. Besides, the pH of the soil was seen to affect Diplura only in the autumn season. The relation of fauna with the physicochemical parameters (temperature, moisture, and pH) and also with other taxa showed their ecological roles and adaptation to a specific microclimate.</p> </abstract>ARTICLE2022-04-22T00:00:00.000+00:00en-us-1