Modelling ecotoxicity of polybrominated diphenyl ethers in aquatic ecosystems

Polybrominated diphenyl ethers (PBDEs) are commercially-produced substances that are used as flame retardants in a wide variety of consumer products. They are among chemicals of emerging environmental concern and are found to be ubiquitous in the environment--they were detected in sediments, water, fish, and wildlife and in human adipose tissues. Environmental concentrations are lower than those of other persistent organic pollutants (POPs). However, present data show that while levels of POPs such as PCBs and DDT are decreasing, PBDE levels are definitely on the rise. The two most prevalent PBDEs in the environment are BDE47 and BDE99. This research studied the toxicity of PBDEs using Pseudokirchneriella subcapitata (formerly known as Selenastrum capricornutum), Daphnia magna, and Hyalella azteca in laboratory bioassays, by exposing each species to 5 different concentrations (0, 12.5, 25, 50, 100, and 200 [micro]g/l) of BDE47 and BDE99 congeners. PBDEs showed toxicity to D. magna and P. subcapitata and growth was inhibited at the lowest concentration tested, (12.5 [micro]g/l). Neither of the two congeners had measurable effects (in particular, mortality) on H. azteca at the concentrations tested (up to 200 [micro]g/l). A model was developed in order to understand effects of PBDEs on grazing (or predator-prey) relationships using P. subcapitata as a prey species and D. magna as a grazer or predator species. In general, PBDEs have demonstrated the ability to have significant impact on population dynamics of species in a grazing relationship, even at concentrations that caused minimal effects in growth parameters of isolated species. While single species bioassays showed a decrease in biomass of both species with increasing concentrations of PBDEs, our model predicts an increase in algal population, and a disproportionate and significant decline in Daphnia. The research suggest that PBDEs in the natural environment therefore, will not only cause toxic effects on individual sensitive species but also on populations of other organisms with which they interact.

Modelling ecotoxicity of polybrominated diphenyl ethers in aquatic ecosystems

Polybrominated diphenyl ethers (PBDEs) are commercially-produced substances that are used as flame retardants in a wide variety of consumer products. They are among chemicals of emerging environmental concern and are found to be ubiquitous in the environment--they were detected in sediments, water, fish, and wildlife and in human adipose tissues. Environmental concentrations are lower than those of other persistent organic pollutants (POPs). However, present data show that while levels of POPs such as PCBs and DDT are decreasing, PBDE levels are definitely on the rise. The two most prevalent PBDEs in the environment are BDE47 and BDE99. This research studied the toxicity of PBDEs using Pseudokirchneriella subcapitata (formerly known as Selenastrum capricornutum), Daphnia magna, and Hyalella azteca in laboratory bioassays, by exposing each species to 5 different concentrations (0, 12.5, 25, 50, 100, and 200 [micro]g/l) of BDE47 and BDE99 congeners. PBDEs showed toxicity to D. magna and P. subcapitata and growth was inhibited at the lowest concentration tested, (12.5 [micro]g/l). Neither of the two congeners had measurable effects (in particular, mortality) on H. azteca at the concentrations tested (up to 200 [micro]g/l). A model was developed in order to understand effects of PBDEs on grazing (or predator-prey) relationships using P. subcapitata as a prey species and D. magna as a grazer or predator species. In general, PBDEs have demonstrated the ability to have significant impact on population dynamics of species in a grazing relationship, even at concentrations that caused minimal effects in growth parameters of isolated species. While single species bioassays showed a decrease in biomass of both species with increasing concentrations of PBDEs, our model predicts an increase in algal population, and a disproportionate and significant decline in Daphnia. The research suggest that PBDEs in the natural environment therefore, will not only cause toxic effects on individual sensitive species but also on populations of other organisms with which they interact.

The Community of Chlorophyta as Bioindicator of Water Pollution in Pandanduri Dam District of Terara East Lombok

The Pandanduri Dam has a function as a support for agricultural irrigation water and also supports community activities so that it will affect the quality of its waters. The quality of the water needs to be analyzed because it can affect the aquatic ecosystem. This study aims to determine the level of water pollution in the Pandanduri Dam based on the phytoplankton community from the Chlorophyta Division. This type of research is descriptive exploratory. Sampling was carried out at 5 stations that were haphazardly selected with ecological representativeness consideration. Phytoplankton data were analyzed using the abundance formula, Shannon-Wiener diversity index, PIELOU uniformity index, and Simpson dominance index. The phytoplankton from the Chlorophyta Division found in the Pandanduri Dam were 14 species that are Pediastrum duplex var. Gracillimum, Gonium sp. 1, Gonium sp. 2, Coelastrum reticulatum, Scenedesmus acuminatus, Cosmarium sp., Chlamydomonas nasuta, Chlamydomonas sp., Selenastrum capricornutum, Monoraphidium dybowskii, Monoraphidium contortum, Monoraphidium irregular, Westella botryoides, and Kirchneriella lunaris consisting of 4 orders (Sphaeropleales, Chlorococcales, Chlamydomonadales and Desmidiales) and 10 genera (Pediastrum, Coelastrum, Scenedesmus, Gonium, Cosmarium, Chlamydomonas, Selenastrum, Monoraphidium, Westella, and Kirchneriella). The species diversity index of 2.21 is classified as moderate diversity, the species uniformity index is 0.83 which indicates even species growth, and the species dominance index indicates that no species dominates with a value of 0.12. The level of water pollution in the Pandanduri Dam was found in the moderate pollution category (oligotrophic).

Selenastrum capricornutum Prinz, Zea mays L. and Phaseolus vulgaris L. Biomonitors: Natural Monitors of Spent Phone Battery Toxicity

Aims: This study was undertaken to monitor the different effects of spent Toshiba and Dell laptop battery on the growth and germination indices of Selenastrum capricornutum Prinz, Zea mays L. and Phaseolus vulgaris L. Study Design: Five treatments and the controls designs designated as 6.25%, 12.5%, 25%, 50%, 100% and CTRL were set up in triplicates and incubated at 25 ± 2°C for 72 h and 5 days. Place and Duration of Study: Department of Microbiology, Chukwuemeka Odumegwu Ojukwu University (COOU), Uli Anambra State, Nigeria during May, 2019 - December, 2019. Methodology: The algal growth inhibition was analyzed using spectrophotometric method while growth and germination indices were adopted for the seed growth inhibition. Results: The result revealed that the positive control K2Cr2O7 had the lowest ErC10 (-86.65 mg/L) and the highest ErC90 (130.92 mg/L) while the spent Dell battery sample had the highest ErC10 (10.18 mg/L) and spent Toshiba battery sample had the lowest ErC90 (75.52 mg/L) on Selenastrum capricornutum growth rate, respectively. Boric acid standard toxicant had the highest EC50 (-12.62 mg/kg and -14.30 mg/kg) on Z. mays and P. vulgaris while Toshiba and Dell battery samples had the lowest EC50 (-73.03 mg/kg and -22.37 mg/kg) on Z. mays and P. vulgaris, respectively. Conclusion: The study revealed that both S. capricornutum, Z. mays L. and P. vulgaris L. were very good bio-monitoring models for spent Toshiba and Dell laptop battery contamination assessment; and are therefore recommended for E-wastes bioassays.

Toxic Effect of Refinery Industrial Effluent Using Three Toxicity Bioassays

Aims: To determine the toxic effect of refinery industrial effluents using three toxicity bioassays. Study Design: Five treatments and the controls designs were set up in triplicates containing 6.25%,12.5%, 25%, 50%, 100% and 0% of the industrial effluents and incubated at 24°C for 0 - 96 h. The five treatments and control set ups designated as PH, Warri and Control (Without effluent) were used to determine the toxic effect of industrial effluents. Place and Duration of Study: Department of Microbiology, Faculty of Natural Sciences, Chukwuemeka Odumegwu Ojukwu University, Uli Nigeria between September, 2019 and December, 2019. Methodology: A laboratory scale study was carried on two composite samples of the produced water samples from the two studied areas using physicochemical analyses, microalgal toxicity test, mollusk toxicity and Zea mays test. Results: The results revealed that Port Harcourt refinery effluent contains higher quantities of physicochemical parameters than the Warri effluent sample. Warri sample had the most harmful effects on Selenastrum capricornutum, Lymnaea stagnalis and Zea mays, with ErC50 values of 47.62%, LC50 of 51.86% and EC50 of-32.68%, respectively. Inhibition (%) and mortality (%) of all species used were found to be concentration dependent with a significant (P < 0.05) strong positive correlation at increasing concentrations of industrial effluents. Conclusion: Thus, these raw industrial effluents from Port Harcourt and Warri refineries are toxic and induced growth inhibition, mortality and phytotoxicity and adequate measures should be taken by these industries to minimize their negative environmental impacts.

Selenastrum Capricornutum a New Strain of Algae for Biodiesel Production

The increasing global demand for biofuels for energy security and to reduce the effects of climate change has created an opportunity to explore new sources of biomass, of which, microalgae is the most promising one. The Laboratory of the Biomass Research Centre (CRB, University of Perugia) is equipped with a photobioreactor that is used to cultivate microalgae under batch conditions. Tests were carried out a temperature of 22 °C and a Photosynthetic Photon Flux Density of 140 µE·m−2·s−1. Cultures were characterized in terms of biomass produced and lipid fraction distribution. The novelty of this paper is the measure of the fuel properties of Selenastrum capricornutum, a new strain for biodiesel production. In particular, after the microalgae have been collected and oil has been extracted, this has been transesterified using a methanol/NaOH solution. The resulting biodiesel has been analyzed with a high-resolution gas chromatograph to determine the concentration of the different methylesters.

The Toxic Effect of Conventional Treated Mine Water on Aquatic Organisms

The present paper aims to evaluate the toxic effects generated by conventional treated mine water as well as freshwater samples (Macris river) on primary producers (green algae, Selenastrum capricornutum) and primary consumers (planktonic crustaceans, Daphnia magna). Those organisms could be very realiable biological models to assess the toxic effect of mine waters on the environment. The green algae growth inhibition test (performed according to OECD201) and the acute immobilization test of freshwater crustaceans (Daphnia magna) (performed according to OECD 202) showed no growth inhibition or Daphnia magna immobilization / mortality during 72h and 48h incubation in presence of surface water samples from Macris river. The aqueous system with 1.89 g/L sulphate ion (SO42-) concentration, containing treated mine water mixed with freshwater sample (ratio 2.4:1), generated 100% toxic effect on crustaceans (Daphnia magna) after 48h incubation.