Department of Chemistry

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Population characteristics of Oreochromis esculentus in the Victoria and Kyoga lake basins. Implications for conservation and improvement of the stocks
(Blackwell Publishing Ltd, Afr. J. Ecol., 2006) Nagayi-Yawe, K. J.,; Ogutu-Ohwayo, R; Kizito, Y. S; Balirwa, J. S.
The tilapiine fish Oreochromis esculentus, is endemic to only lakes Victoria and Kyoga and a few satellite lakes in the two lake basins. It was the most important commercial fish species during the first half of the 20th century in the two lake basins but because of over-exploitation and competition with introduced tilapiines, its stocks declined and, by 1980s, O. esculentus was virtually absent from the two main lakes. Lakes Mburo, Kachera, Kayanja and Kayugi in the Lake Victoria basin, and Nabisojjo, Kawi and Lemwa, in the Lake Kyoga basin, where remnants of the species survived were investigated using experimental fleets of gillnets from 1997 to end of 2002 with the objective of determining the species length frequency distribution, condition factor, feeding and breeding to guide its management, conservation and enhancement. Fish caught in Lake Kayugi, where diatoms dominated in the stomach contents attained the largest size, were most fecund and had a high value of condition factor K.These findings suggest that diatoms were vital in the survival of O. esculentus. However, with the recent shift of algal communities from diatoms to blue-green algae in most aquatic systems, assimilation of blue-green algae by O. esculentus should be investigated.
Speciation of heavy metals in water from the Uganda side of Lake Victoria
(Tailor and Francis, 2010-02) MBABAZI, JOLOCAM; TWINOMUHWEZI, H.; WASSWA, J.; NTALE, M.; MULONGO, G.; KWETEGYEKA, J.; SCHR DER, K.H.
Different forms of copper Cu, zinc Zn, lead Pb and cadmium Cd in water from the Uganda side of Lake Victoria (25°C, pH 6.75–7.18), the second largest inland freshwater lake in the world, have been studied using ion-exchange, dialysis and atomic absorption spectrophotometry. The results indicate that heavy metals Cu, Zn, Pb and Cd are present mainly in the cationic form (80–83%). Small quantities of anionic (13–22%), non-ionic, dialyzable (4–8%), and non-ionic, non-dialyzable (< 1.3–4.4%) forms were also detected for all metals except Cd. The corresponding concentrations lay in the ranges: cationic, 0.06–0.99; anionic, < 0.001–0.25; non-ionic, dialyzable, < 0.001–0.08; non-ionic, non-dialyzable, < 0.001–0.06 µg ml−1 . The existence of the metals in non-ionic and nondialyzable forms is attributable to metal associations with high relative molecular mass (RMM) organic matters.
Water Bactericidal Properties of Nanosilver- Polyurethane Composites
(Nanoscience and Nanotechnology., 2011) Mulongo George; Mbabazi Jolocam; Proscovia Nnamuyomba,; Song Hak-Chol
A technique for coating polyurethane with silver nanoparticles freshly prepared using a hydroxyethyl cellulose organic polymer is presented. The ensuing silver nanoparticle – polyurethane foam composite is found to possess such antibacterial properties as might be useful in water disinfection. With the help of electron microscopy and FTIR spectrophotometry, it was revealed that the adsorption of metallic silver onto the organic polymeric substrate could be attributed to silver nanoparticulate interaction with the nitrogen in the ─NH─ bond in polyurethane. Contrary to earlier reports that similar preparations had total bactericidal effects on water-borne microorganisms, a number of microbial analyses performed on Basillus Subtulis 15 and E. coli 36 as test bacteria in infected waters exhibited only 9 and 5 live percentages, respectively, after eluation through the composite-packed column.
Stannate (IV) and Antimonate (V) Hexahydroxy-anion complexes with Di- and Polyhydric Phenols
(Research Journal of Chemical Sciences, 2011-05-02) Mbabazi, Jolocam; Ntale, M.; Kwetegyeka, J.; Mulongo, G.; Twinomuhwezi, H.; Nnamuyomba, P
An identification has been achieved of only 1:1 and 1:2 chelates of hexahydroxystannate (IV) anions with ortho (i.e., 1,2)-diphenols, using potentiometric and conductimetric techniques. Lack of evidence for organo-richer complexes in aqueous media is in contrast to antimonite (V) hexahydroxy anions and tellurate (VI), which are each able to form a tris (catecholate).
Dichloro-diphenyl-trichloroethane (DDT) residue levels in marketed Silver Fish (Rastreneobola argentea) caught from major water bodies in Uganda
(Academic Journal, 2014-06-25) Nnamuyomba, Proscovia; Mbabazi, Jolocam; Ntale Muhammad
Silver fish (Rastreneobola argentea) samples from Lake Victoria and Lake Kyoga were analyzed for dichloro-diphenyl-trichloroethane (DDT) and metabolites using a Gas Chromatograph equipped with an Electron Capture Detector. Confirmation of results was by Gas Chromatography equipped with Mass Spectrophotometer (GC-MS). DDT and metabolites were detected in 90% of the total samples (63 out of 70). pp’ DDT was the most frequently detected residues in the samples whereas op’ DDE was detected in none of the samples. The mean ΣDDT concentrations in fish from Lake Victoria varied from 0.147 to 0.396 µg/kg while that in Lake Kyoga varied from 0.207 to 0.506 µg/kg dry wt of fish sample. The concentration of total DDT in the fish samples ranged from 0.147 to 0.506 µg/kg dry wt. This was far below the recommended FAO limit of 5000 µg/kg for fish (edible portion), implying that the fish are safe for human consumption.
1,1,1-Trichloro-2,2-bis(p-chlorophenyl)ethane (DDT) and its derivatives in marketed Clarius werneri caught from Uganda’s major urban wetlands
(Journal of Toxicology and Environmental Health Sciences, 2014-07-29) Nnamuyomba, Proscovia; Jolocam Mbabazi; Muhammad Ntale
The presence of 1,1,1-trichloro-2,2-bis(p-chlorophenyl)ethane (DDT) and derivatives in the Clarius werneri of Uganda’s major urban wetland ecosystems was investigated. Solid dispersion extraction method for extraction, florisil column method for clean-up, gas chromatograph equipped with an electron capture detector (GC-ECD) for analysis and gas chromatograph equipped with mass spectrophotometer (GC-MS) for confirmation of results were used in this study. The major DDT contaminants detected in the samples were p,p’-DDD, p,p’-DDE and p,p’-DDT which were found in 25, 22 and 21% of the samples, respectively. o,p’-DDD was detected in 19% and o,p’-DDT in 13% of the samples. For o,p’-DDE there were no measurable values since the levels were below limit of quantitation (LOQ). The concentrations of DDT derivatives ranged between ND-0.478 µg/kg for p,p’-DDE, ND-0.387 µg/kg for o,p’-DDD, ND-0.476 µg/kg for p,p’-DDD, ND-0.345 µg/kg o,p’-DDT and ND-0.556 µg/kg for p,p’- DDT. The concentration of total DDT in C. werneri was in the range of 1.111 to 1.328 µg/kg dry wt. Generally, all the samples had DDT derivative levels below the maximum residue limit recommended by Food and Agriculture Organisation/World Health Organization (FAO/WHO) Codex Alimentarius Commission.
Trace Elements in Marketed Rastreneobola Argentea and Clarias Werneri Caught from Selected Aquatic Ecosystems in Uganda
(International Journal of Current Trends in Engineering & Technology, 2015-08) Nnamuyomba, Proscovia; Mbabazi, Jolocam; Ntale, Muhammad
Samples of two fish species Rastreneobola argentea and Clarias werneri from Lake Victoria, Lake Kyoga and Nakivubo and Lubigi wetlands were analysed for Cu, Zn, Pb and Cd using an Atomic Absorption Spectrophotometer - Perkin-Elmer Model 2380. The results revealed that Zn concentrations were the highest in both species, followed by Cu; Pb and Cd being the lowest. The concentrations of Cu, Zn, Pb and Cd in R. argentea from Lake Victoria ranged between 20.5- 115 µg/Kg, 175 - 495 µg/kg, 15 - 77.5 µg/Kg and 2.5 - 4.45 µg/kg respectively, mean while their concentrations in the same fish species from Lake Kyoga ranged between 12.5 - 37.5 µg/kg (Cu), 35-100 µg/kg (Zn), 5-12.5 µg/kg (Pb), 0.5-1.5 µg/kg (Cd) dry weight. In C.werneri, heavy metals varied between 197-337.5 µg/kg (Cu), 235-670 µg/kg (Zn), 60-77.5 µg/kg (Pb) and 2.5-6.98 µg/kg (Cd) in Lubigi wetland and in Nakivubo wetland, concentrations of heavy metals ranged between 7521320 µg/kg for Cu, 1230-1437 µg/kg for Zn, 85-97.5 µg/kg for Pb and 2.2-7.75 µg/kg for Cd. Heavy metal concentrations obtained in this study were below permissible limits issued by WHO/FAO. Therefore, the consumption of these fish species may not pose any threat to human health. However periodic monitoring of these metals in the fish caught from water bodies located in urban areas is highly essential to public health
The impact of septic systems density and nearness to spring water points, on water quality
(African Journal of Environmental Science and Technology, 2017-01-18) Arwenyo, B.; Wasswa, J.; Nyeko, M.; Kasozi, G. N.
Worldwide, 1.1 billion people do not have access to clean water and as a result, 2 million children die annually due to preventable waterborne diseases. In Uganda, 440 Children die every week of waterborne diseases. High prevalence of this death is reported in the peri urban areas. It is still unclear however the causes of water pollution in the peri-urban areas. The improper use of onsite sanitation facilities such as latrines and septic systems may lead to groundwater contamination. It is true that drain field of septic system located too close to water point, and or over population of the septic systems in a small area can lead to pollution of groundwater. Our study investigated the impact of septic systems density and nearness to water points on spring water quality. Samples from 15 spring wells were analysed for pH, nitrate and faecal coliform contamination. Locations and distances of spring from septic systems were determined using global positioning system (GPS) device and ArcGIS software, respectively. Water samples from all the spring wells had pH value less than 6.5, 66.7% had faecal coliform and 53% had nitrate above 2 mg L-1. While sample from one of the springs had nitrate concentration above the United States Environmental Protection Agency (US EPA) standard of 10 mg L- 1. It was also noted that coliform counts and nitrate concentrations increases with increase in number of septic systems surrounding the spring well. In addition, increase in distance between spring wells and septic systems indicated decrease in both coliform counts and nitrate concentration. It is therefore concluded that improper use of septic systems is one of the causes of groundwater pollution in the peri urban areas. The study recommends treatments of water from groundwater sources, regular monitoring of groundwater sources and proper design and siting of septic systems using more robust methodologies.
Phosphorus availability from magnesium-modified P-enriched Douglas fir biochar as a controlled release fertilizer
(Soil Use and Management, 2021-08-04) Arwenyo, Beatrice ; Varco, Jac J.; Dygert, Andrew ; Mlsna, Todd
Phosphorus (P) is one of the essential elements required for plant growth and de velopment. However, worldwide, many agricultural soils can be deficient in P. The use of fertilizers and manures as a source of P can be costly, limited in sup ply in some regions of the world and ecologically unfavourable. Nutrient-enriched biochar has been suggested as a relatively cost-effective and eco-friendly P source. This study investigated P availability from Douglas fir biochar modified with mag nesium chloride and potassium hydroxide solutions only (B), and modified P enriched Douglas fir biochar B50, B100 and B150 corresponding to B treated with 50, 100 and 150 mg P L−1 solutions of potassium phosphate monobasic. Triple super phosphate fertilizer (FC) and a control treatment without phosphate added (C) used as a reference treatment. Treatments were added to soil in varied amounts to obtain the same P rate of 30 kg P ha−1. Aboveground biomass dry weight yield (R2 = .7) and plant height (R2 = .86) improved with P contents. After harvest, re sidual soil P for the FC treatment was significantly greater than all other treatments (p-value = 1.7848 E-6, R2 = .8). Plant height and aboveground dry weight biomass were greater with B150 compared to B50 at the same total P loading, suggesting that the greater P concentration of the biochar (B150) resulted in less tightly bound P and was therefore more available for plant uptake. This study showed promise of utilizing P-enriched Douglas fir biochar as a slow-release P fertilizer.
Effects of thermal acclimation and ecological background on the physiological responses of juvenile Oreochromis esculentus (Graham, 1928). Implications for the species adaptive capacity to global warming
(Aquaculture Research, 2021-10-12) Nagayi, Jane Kalule Yawe; KisakyeJohn , Joseph; Tenywa Mwanja, Matthew; Nattabi; Opio Alfonse
Climate change is a recognized global concern in the 21st century. Water temperature elevation is likely to affect fish physiological and ethological function, causing great economic losses for fisheries resources and aquaculture production. Fish are particularly vulnerable to climate change as they are unable to control their body temperatures with changes in environmental temperature. This study assessed the effects of thermal acclimation in three juvenile populations of Oreochromis esculentus on the critical thermal maximum CTmax, cortisol, biochemical and haematological responses to acute temperature increase (0.3°Cmin−1). Fish from Senya farm, Lake Kacheera and Lake Nabisojjo were acclimated at 25°C, 28°C, 31°C and 34°C for 21 days at Kajjansi aquaculture research and development centre KARDC. The CTmax and blood cell counts increased, while plasma cortisol, glucose and proteins decreased at higher acclimation temperatures. Two-way ANOVA showed significant differences among treatments in CTmax, cortisol, proteins and erythrocytes indices, but not in glucose and leucocytes. However, significant variations among populations were only showed in CTmax. Overall, these results suggest that O. esculentus can respond to higher climate change induced temperatures, when allowed time for acclimation. Since temperature adaptation not only depends on the parameters assessed in this study, we recommend further investigations into metabolic rate and digestive enzymatic activity.
Kinetics and Thermodynamic Studies: Adsorption of Pb, Cr and Ni Ions from Spent Lubrication Oil (SLO) Using Acid Modified Clay
(American Journal of Analytical Chemistry, 2021-12) Sughnen Atsar, Felix; Kukwa, Donald; Ahule Wuana, Raymond; Arwenyo, Beatrice
Adsorption of Pb, Cr, and Ni ions from spent lubrication oil (SLO) by sulphuric acid modified clay (SAMC) was investigated considering the effect of contact time and temperature of the adsorption system. The removal percentage of the heavy metals was found to be temperature and contact time-dependent. Adsorption of the heavy metals increases with an increase in temperature and contact time with 95.0% - 100% adsorption recorded at the temperature of 331 K with the equilibration time of 12 hours. The thermodynamic and kinetics investigation of the adsorption process showed that the adsorption of these metals by the modified adsorbent is a spontaneous and endothermic physical adsorption process that followed the pseudo-second-order kinetic model.
Lead immobilization in simulated polluted soil by Douglas fir biochar-supported phosphate
(Elsevier Chemosphere, 2021-12-16) Varco, Jac J.; Dygert, Andrew; Atsar, Felix S.; Solomon, Sabrina; Venkatesh, Rooban; Thirumalai, K.G.; Pittman Jr., Charles U.; Mlsna, Todd
This study compared the lead (Pb2+) immobilization efficacy of biochar-supported phosphate to conventional in situ heavy metal immobilization methods (with lime, neat biochar and phosphate). The biochar-supported phosphate was obtained by treating Douglas fir biochar (BC) with anhydrous calcium chloride and potassium dihydrogen phosphate. The amount of Pb2+ immobilized was determined by comparing the concentration of ammonium nitrate extractable Pb2+ lead from lead-spiked soil (without amendment) to that of a 30 d incubation with (a) lead-spiked soil plus 5% (wt./wt.) biochar supported-phosphate, (b) lead-spiked soil plus 5% (wt./wt.) untreated Douglas fir biochar, (c) lead-spiked soil plus 5% (w/w) lime and (d) lead-spiked soil plus 5% (wt./wt.) potassium dihydrogen phosphate. The control (lead-spiked soil without amendment) produced the largest quantity (96.08 ± 9.22 mg L− 1 ) of NH4NO3-extractable Pb2+, while lead-spiked soil treated with 5% (wt./wt.) biochar-supported phosphate resulted in the lowest quantity of NH4NO3 extractable Pb2+ (0.3 ± 0.2 mg L− 1 ). The mechanism for immobilization of Pb2+ by BP occurs at pH < 7 through dissolution of hydroxyapatite embedded in BP during modification, followed by precipitation of insoluble Pb10(PO4)6(OH)2. The residual lead fraction in the lead-spiked soil increased by 20.9% following amendment with BP. These results indicate that biocharsupported phosphate is a candidate to reduce lead mobility (bioavailability) in polluted soil. This amendment may lower Pb2+ uptake into plants while minimizing the potential for water contamination due to Pb2+mobility.
Application of biochar for the removal of actinides and lanthanides from aqueous solutions.
(Elsevier Inc., 2022) Bursztyn, Amalia L. Fuentesa; Arwenyo, Beatrice; Nanney, Andie L.M.; Ramirez, Arissa; Jamison, Hailey; Venson, Beverly; Mohan, Dinesh; Mlsna, Todd E.; Navarathna, Chanaka
Actinides and lanthanides are elements with unfilled f orbitals and are collectively labeled as the inner transition elements (ITEs). The actinide series includes 15 radioactive metallic ele ments with atomic numbers 89–103 (Cooper, 2000). The actinide elements are classified as light (Ac, Th, Pa, U, Np, Pu, Am) or heavy (Cm, Bk, Cf, Es, Fm, Md, No, Lr) based on their atomic numbers. The actinides fill their 5f sublevels progressively and exhibit char acteristics of both the d-block and the f-block elements. Elements of the actinide series can have oxidation states from +2 to plus +7. In addition to being radioactive, all actinides are paramagnetic and pyrophoric. Except for actinium with one oxidation state of +3, the other actinides are known to show variable oxidation states and more than one crystalline phase. To date, only the first four elements in the actinide series have been found to occur naturally.
Sustainable Biochar for Water and Wastewater Treatment
(Elsevier Inc. All rights reserved, 2022) Mohan, Dinesh (editor); Pittman Jr., Charles U.(editor); Mlsna, Todd E. (editor)
This First Edition was motivated by the recent enormous growth in biochar research. From 2010 to the date this Preface was written, the Web of Science database shows 18,224 publica tions on biochar have appeared. This activity is accelerating. In 2010, 119 publications appeared. This grew to 3975 in 2020. By September 2021, 3588 biochar papers had already been counted for that year. The first use of biochar, as distinct from charcoal or activated carbon, for water remediation appeared in the Jour nal of Colloid and Interface Science in 2007 [JCIS, 310(1)2007, 57–73]. Fast pyrolysis by-product biochar obtained from biooil production in an auger-fed reactor was used to remove heavy metals from water. Following this publication, many reports on slow and fast pyrolysis biochar as a substitute for activated carbon in water purification have appeared. Previously, biochar had been used for soil enrichment and carbon sequestration.
Phosphorus enriched modified-Douglas fir biochar as a soil Phosphorus enriched modified-Douglas fir biochar as a soil amendment
(Mississippi State University Mississippi State University Scholars Junction, 2022-05-13) Arwenyo, Beatrice
Biochar application as a soil additive is gaining global acceptance. In this era of climate change, biochar use for improved soil productivity is not just a sustainable eco-friendly substitute to synthetic fertilizer, but a noble contributor to the fight against climate change. Although biochar has been accredited with some environmental and agricultural benefits, most studies concentrated on agricultural and biowaste products as feedstocks. This research was designed to explore Penriched modified-Douglas fir biochar potential as a soil additive. Using corn as a test crop, greenhouse studies were performed on acidic sandy soil, comparing phosphorus enriched modified-Douglas fir biochar efficacy to a commercial synthetic triple superphosphate fertilizer and a control treatment. Incubation studies were also performed to evaluate the liming and heavy metal immobilization efficacies. Firstly, P-enriched modified-Douglas fir biochar’s ability to release plant soluble P was investigated. At various P enrichment concentration, soil plant availability P from P enriched modified-Douglas fir biochar treatments differed insignificantly from superphosphate fertilizer treatment. The direct correlations between both K and Mg recoveries with available soil P, suggested P enriched modified-Douglas fir biochar potential to supply multiple plant nutrients. Secondly, the influence of P uptake on plant growth and P use efficiency was examined. The greater agronomic P use efficiency obtained in P enriched modified Douglas fir biochar (~32 kg kg-1) than the triple supper phosphate fertilizer (~17 kg kg-1) treatment confirmed P enriched modified-Douglas fir biochar potential as a multiple nutrient released soil additive. Thirdly, biochar-supported phosphate (BP) effectively reduced Pb2+ mobility in simulated contaminated soil. Pb2+reacted with phosphate from Ca10(PO4)6(OH)2 embedded in the biochar supported phosphate at pH<7 forming a less bioavailable Pb10(PO4)6(OH)2. Finally, the amendment of acidic soils with modified P-enriched modified-biochar improved soil buffering capacity because of its enhanced ash contents, alkalinity, and surface functional groups. Spectroscopic methods were used to analyze biochar, soil, and plant materials extracts. Several other analytical methods including BET and thermogravimetric analyses were used to characterized biochar. These findings suggest that the use of phosphorus enriched modified Douglas fir biochar in agricultural soil is a feasible relatively low-cost, effective, and environmentally sustainable soil management and P recycling strategy
Dichlorodiphenyltrichloroethane (DDT) and its metabolites in house dust, soil and selected food crops from indoor residual sprayed areas of Apac and Oyam Districts, Uganda
(African Journal of Pure and Applied Chemistry, 2022-06-12) Mukasa paul; Wasswa John; Namuyomba Proscovia; Ntambi Emmanuel
Dichlorodiphenyltrichloroethane (DDT) levels and its metabolites are reported in 75 soil and 75 vegetable samples from the vicinity of homesteads sprayed with DDT during indoor residual spraying (IRS) pilot exercise, carried out in 2008 in Apac and Oyam districts, Uganda as a measure to control malaria. The samples were randomly and conveniently collected in 2020 from selected villages of the districts, extracted using solid dispersion and multi-residue methods for soil and vegetable samples, respectively and analyzed using GC-ECD and GC-MS. DDT residues were detected in all samples collected. The ΣDDT (µg kg-1) in all indoor house dust, outdoor soil samples from villages of Apac and Oyam districts and control areas were 69.9±20.9 and 8.9±4.7, 113.4±22.6 and 15.4±4.3, and 1.13±0.27 and 1.8±0.9, respectively. ΣDDT were significantly higher (p < 0.05) in the study areas than the control areas. In vegetables, ∑DDT (µg kg-1) ranged between 1.7±0.3 and 8.3±4.0 and 2.3±0.4 and 11.4±7.5 in the study and control areas, respectively. Abelmoschus esculentus and Gynandropsis gynandra had the highest levels. The results suggest that IRS had an effect on DDT levels in the environment. However, ∑DDT in vegetables were significantly below (P < 0.05) the EU EMRL, thus, the results raise no concern regarding the potential health effects of DDT to the residents. Nevertheless, due to bioaccumulation effects of DDT, to control malaria, measures like Ecohealth rather than IRS of DDT should be embraced.
Effects of environmental temperature on the growth performance of a tropical Oreochromis esculentus (Graham, 1928). Implications for the species conservation
(Willey., 2022-09-14) Nagayi, Kalule Yawe jane; Kisakye Joseph; Tenywa Mwanja Matthew ,; Nattabi. Juliet; Opio Alfonse
Climate variability and change are currently recognised global challenges. However, the impacts of rising temperatures may be greatest on tropical freshwater fish, which already exist in warm environments and may be living close to their critical thermal maximum. However, there is limited species- specific information on tropical species’ adaptive capacity to increased temperature. This study examined various growth attributes in juvenile populations (farmed, L. Kacheera and L. Nabisojjo) of a critically endangered tropical Oreochromis esculentus to determine its adaptive potential. Fish were acclimated at 25, 28, 31 and 34°C for 28 days. Overall, survival rates were high. Growth coefficient b was not significantly different from three (b = 3) in all treatments, implying isometric growth. The specific growth rates (SGRs), body condition K, and hepato- somatic indices (his) declined as the acclimation temperatures increased. Although SGR showed significant variations only among populations, the highest in L. Nabisojjo, K and HSI showed significant variations among treatments. Overall, the growth attributes declined at higher acclimation temperatures, but remained within acceptable ranges, implying that the species may attain normal growth at elevated temperatures experienced in outdoor aquaculture systems, despite its warm environmental background. Hence, we recommend selective breeding for temperature resilience and species introduction into aquaculture using broodstock from L. Nabisojjo.
Uptake of Phosphorus from Modified P-Enriched Douglas Fir Biochar and Its Effects on Crop Growth and P Use Efficiency
(Journal of Geoscience and Environment Protection, 2022-09-29) Arwenyo, Beatrice; Varco, Jac J.; Dygert, Andrew; Berry, Jaime; Mills, Julianna; Mohan, Dinesh; Pittman, Charles U.; Mlsna, Todd
The potential use of biochar as a sustainable soil amendment has recently gained global recognition. The use of biochar as a soil additive is attributed to its ability to improve soil chemical, physical and biological properties. Studies have shown that biochar amendments can enhance soil nutrient retention and availability, pH, water holding capacity, microbial activity and sequester car bon. In this study using corn (Zea mays L.) as an experimental crop, the in fluence of P availability from modified P enriched Douglas fir biochar (PEB), triple super phosphate fertilizer (SPF), and modified Douglas fir biochar (MB) on plant growth and P Use Efficiency (PUE) were compared. The rate of P applied (0, 30, 60, 90 and 120 kg·ha−1 ) was calculated based on % P content of each soil additive. Except for MB treatments, P recovery, crop growth and P Use Efficiency increased with application rates. The maximum above ground dry matter yields corresponding to PEB, SPF and MB treatments were esti mated at 3488 kg·ha−1 , 2449 kg·ha−1 and 639 kg·ha−1 , while their respective agronomic P use efficiency (AGE) rates were 32 kg·kg−1 , 17 kg·kg−1 , 0.5 kg·kg−1 . Also, recovery of K, Mg, Ca, Zn, Fe, Cu, B and Mn improved in both PEB (p value < 0.0003, r2 > 0.9) and SPF (p value < 0.0058, r2 > 0.9) treatments. More studies at field scale are needed to demonstrate the practicability of using modified P enriched Douglas fir biochar for soil amendments.
Contribution of modified P-enriched biochar on pH buffering capacity of acidic soil
(Elsevier Journal of Environmental Management, 2022-11-06) Arwenyo, Beatrice; Varco, Jac J.; Dygert, Andrew; Brown, Sydney; Pittman, Charles U.; Mlsna, Todd
Biochar can directly hold cations in soil because of the negative charge that exists on its surfaces. Besides, improving soil cation exchange capacity, the negative charges on biochar surfaces can buffer acid soil by pro tonation and deprotonation mechanisms. Moreover, biochar ameliorates soil acidity due to the presence of ox ides, carbonates, and hydroxides of its basic cations (Ca, Na, K, and Mg). Both biochar surface functional group and basic cation concentrations can be altered by modification with chemical agents which can affect its soil pH buffering capacity. However, the impact of modified biochar application on soil pH buffering capacity is still scanty. This study investigated the pH buffering capacity of acidic soil amended with three P-enriched modified Douglas fir biochars and compared this buffering capacity to amendment with untreated Douglas fir biochar. These three P-enriched biochars, were prepared by treating Douglas fir biochar (DFB), respectively, with: 1) anhydrous calcium chloride (CaCl2) and potassium phosphate monobasic (KH2PO4), 2) calcium carbonate (CaCO3) and diammonium phosphate {(NH4)2HPO4} and 3) an aqueous solution of magnesium sulfate (MgSO4), potassium hydroxide (KOH) and potassium phosphate monobasic (KH2PO4). The three P-enriched biochars were designated as CCPP, CAPP and MSPP, respectively. The soil pH buffering abilities were largely dependent on the added biochar’s alkalinity and ash contents. The residual soil CEC was highly correlated (r ≥ 0.9), with the soil buffering capacity. Both alkalinity and pH buffering capacity improved following the order CCAP > CCPP > MSPP > DFB, while residual soil CEC followed the order CAPP > MSPP > CCPP > DFB. The pH buffering ca pacity of the soil after amendments with 10% CAPP, CCPP MSPP and BFB rose by 84.8, 58.3, 3.0 and 2.5%, respectively. Whereas MSPP had higher concentrations of K+ and Mg2+, greater concentrations of Ca2+ were present in CCAP and CCPP than MSPP. So, Ca2+ concentrations in biochar exerts a greater influence on alkalinity and buffering capacity than Mg2+ and K+ because of 1) its smaller effective hydration radius and larger charge density. 2) calcium hydroxide has a greater water solubility than magnesium hydroxide providing more available base. Since pH buffering capacity depends on cation exchange sites, soil additives containing Ca2+ are prone to create greater impacts than Mg2+ and K+ additives.
Microplastics and Per- and Polyfluoroalkyl Substances (PFAS) Analysis in Sea Turtles and Bottlenose Dolphins along Mississippi’s Coast
(MDPI, Basel, Switzerland., 2023-01-18) Navarathna Chanaka M.; Pray Hannah; M Prashan. Rodrigo; Arwenyo Beatrice; McNeely Cassidy; Reynolds Henry; Hampton Natalie; Lape Katherine; Katie Roman; Heath Maddie; Stokes Sean; R Sameera. Gunatilake; Ariunbold Gombojav; Perez Felio; V. K. G Rooban . Thirumalai; Hassan EI Barbary; Elsayed Islam; Mohan Dinesh; Brown Ashli ,; Moore Debra; Reichley Stephen; Lawrence Mark; MlsnaTodd E.
Global plastic production and usage has increased annually for decades and microplastic pollutants ( 5 mm) are a growing concern. Microplastics in surface waters can adsorb and desorb harmful chemicals such as per- and polyfluoroalkyl substances (PFAS). Microplastics can accumulate across all tropic levels in the marine food web. The purpose of this research was to analyze the stomach and intestinal contents of stranded (Mississippi coast) bottlenose dolphins and sea turtles for the presence of microplastics and commonly found PFAS, PFOS, PFOA, and GenX. Gut contents were digested (10% KOH in 50% MeOH) and then analyzed for microplastics using pyrolysis gas chromatography-mass spectrometry (Pyro-GC-MS), Nile red microscopy, X-ray photo electron spectroscopy (XPS), and Raman spectroscopy. Digested sample filtrate was pre-concentrated using solid-phase extraction (SPE) before PFAS liquid chromatography-tandem mass spectrometry (LC-MS/MS) analysis. The PFOS extraction and analysis had 98.6% recovery when validated with certified pike-perch fish reference material. The Nile red testing on most samples revealed the presence of microplastics (Table S1). The Pyro-GC-MS results from two samples confirmed the presence of the plasticizer acetamide. The Raman spectroscopy analysis indicated characteristic plastic peaks corresponding to polystyrene in one sample. PFOS (95.5 to 1,934.5 g/kg) was detected in three dolphin stomach samples. This project is part of a long-term study with the goal of a better understanding of microplastics and PFAS environmental contamination and their impact on bottlenose dolphins and sea turtles.

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