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Developing Cultural and Environmental Awareness through Active Learning and Collaboration in the Library
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A messy situation: effects of treated human wastewater on aquatic biota
Get PDFRemoval of personal care products (PCPs), pharmaceuticals and other substances
from human wastewater is often unsuccessful and released back in to receiving water.
This includes anti-psychotics and cosmetic additives, and inorganic nitrogen. These
substances are capable of producing unintended biological changes in aquatic biota
located downstream from wastewater treatment plants. The present study examined
whether wastewater would cause adverse effects in aquatic biota. Medaka (Oryzias
latipes) and the zooplankton (Daphnia magna) were used in a controlled laboratory
study. Medaka and Daphnia were exposed to 0 %, 50 % and 90 % wastewater. Mortality,
development, and reproduction (only in Daphnia) were observed. Daphnia were exposed
as neonates and the medaka were exposed as eggs and hatched larvae. There was a
significant beneficial effect of wastewater on Daphnia mortality, growth and reproduction
(p < 0.001). While in contrast, wastewater had a significant negative effect on the medaka
rate of hatching and embryo mortality (p < 0.05). These outcomes suggest that there are
ecologically important changes occurring as a result of the release of wastewater into
natural water bodies. In addition, this study also iterates the significance of using multiple
organisms in environmental toxicological studies.Honours Thesis Course, Department of Biolog
Gypsum Amendment Reduces Redox-Induced Phosphorous Release from Freshly Manured, Flooded Soils to Floodwater
Get PDFThe effectiveness of gypsum in reducing runoff P losses from soils and the mechanisms responsible are well documented; however, gypsum amendment effects in reducing redox-induced P losses from flooded soils are less researched and documented. We examined the effect of gypsum amendment on P release from freshly manured soils to pore water and floodwater with continuous flooding for 56 d in the laboratory. Three soils (Pembina, Denham, and Dencross series) collected from Manitoba, Canada, were preincubated with liquid swine manure. Each preincubated manured soil was packed into vessels with or without recycled wallboard gypsum in triplicates and flooded for 56 d, during which pore water and floodwater were sampled weekly and analyzed for pH and dissolved reactive P (DRP), Ca, Mg, Fe, and Mn concentrations. Change in soil redox potential (Eh) with flooding was also monitored. Wallboard gypsum amendment significantly decreased the pore water and surface floodwater DRP concentrations in all three soils for most days after flooding (DAF). The Dencross soil, which had Olsen P about fivefold greater than the other soils, showed the greatest magnitude decrease in DRP concentration with gypsum amendment, by 1.27 mg L−1 on 49 DAF and 0.99 mg L−1 on 21 DAF for pore water and floodwater, respectively. Gypsum amendment (i) delayed the Eh reduction with flooding beyond +200 mV, (ii) decreased pore water pH, and (iii) increased concentrations of Ca, Mg, and Mn in pore water favoring precipitation of P, all of which may have directly or indirectly reduced the P release from flooded soils to overlying floodwater.Funding for this research was provided by the University of Winnipeg Major Grant and a Natural Sciences and Engineering Research Council Discovery Grant to Darshani Kumaragamage, and a fellowship awarded by the Queen Elizabeth Advanced Scholar Program to R.S. Dharmakeerthi.https://acsess.onlinelibrary.wiley.com/doi/10.2134/jeq2018.08.030
The role of wetland coverage within the near-stream zone in predicting of seasonal stream export chemistry from forested headwater catchments
Get PDFPostprint version. "This article has been accepted for publication and undergone full peer review but has not been through the copyediting, typesetting, pagination and proofreading process which may lead to differences between this version and the Version of Record."Stream chemistry is often used to infer catchment‐scale biogeochemical processes. However, biogeochemical cycling in the near‐stream zone or hydrologically‐connected areas may exert a stronger influence on stream chemistry compared with cycling processes occurring in more distal parts of the catchment, particularly in dry seasons and in dry years. In this study, we tested the hypotheses that near‐stream wetland proportion is a better predictor of seasonal (winter, spring, summer and fall) stream chemistry compared with whole‐catchment averages and that these relationships are stronger in dryer periods with lower hydrologic connectivity. We evaluated relationships between catchment wetland proportion and 16‐year average seasonal flow‐weighted concentrations of both biogeochemically‐active nutrients, dissolved organic carbon (DOC), nitrate (NO3‐N), total phosphorus (TP), as well as weathering products, calcium (Ca), magnesium (Mg), at ten headwater (< 200 ha) forested catchments in south‐central Ontario, Canada. Wetland proportion across the entire catchment was the best predictor of DOC and TP in all seasons and years, whereas predictions of NO3‐N concentrations improved when only the proportion of wetland within the near‐stream zone was considered. This was particularly the case during dry years and dry seasons such as summer. In contrast, Ca and Mg showed no relationship with catchment wetland proportion at any scale or in any season. In forested headwater catchments, variable hydrologic connectivity of source areas to streams alters the role of the near‐stream zone environment, particularly during dry periods. The results also suggest that extent of riparian zone control may vary under changing patterns of hydrological connectivity. Predictions of biogeochemically‐active nutrients, particularly NO3‐N, can be improved by including near‐stream zone catchment morphology in landscape models.Funding for this project was provided by a Natural Sciences and Engineering Research Council of Canada Discovery Grant to MCE.https://onlinelibrary.wiley.com/doi/abs/10.1002/hyp.1341
