9441 research outputs found
Sort by
Assessing Stormwater Management Pond Water Quality, Function, and the Potential Biotic Effects to Receiving Waters
Get PDFThe use of stormwater management ponds (SWMPs) has been increasing over the past five decades. However, an in-depth understanding of the daily performance of SWMPs and functionality during cold periods is limited. This is in part because mandated monitoring is relatively infrequent, and the assumption that SWMPs are inactive between storm events and during the winter. The goals of this research were to better understand daily stormwater (SW) characteristics, the performance of SWMPs based on current forms of evaluation and assess the potential for SWMP effluent to impact downstream biota. Influent and effluent samples from two SWMPs were collected daily for 1-year and analyzed for total phosphorus (TP), chloride (Cl-), total suspended solids (TSS), turbidity (Tb), dissolved oxygen (DO), pH and water temperature (WT). The characteristics of SW influent varied between locations and seasons for all parameters except water temperature, which varied across seasons but not locations influent. SW effluent varied between locations and seasons for all parameters except Tb which differed between locations and TSS which was consistent among seasons and location. The number of days with positive removal efficiencies or (influent\u3eeffluent concentrations) differed among water quality parameters and location and ranged from a high of 82% of the time for chloride at the Dorwood SWMP and a low of 34.2% for Tb at the Yarmouth SWMP. Effluent concentrations of TP were above eutrophic concentrations 10.7 – 40.2% of the time. Cl- concentrations were above chronic exposure values between 88- 99.46% and acute 21.59 – 55.1% of the time. Chronic elevations (5 mg/L) of TSS from background levels occurred between 65-70% of the time and acute elevations (25 mg/L) between 15-25%. Tb remained below elevated exposure values between 81.4 – 98.6% of the time. DO was below recommended concentrations (5.5 mg/L) between 9-29% of the year. WT was higher in effluent compared to the influent approximately 50% of the time. Results indicate the potential for lethal and behavioural effects on taxa including plants, invertebrates, amphibians, and fish in downstream receiving waters. More extensive monitoring of conditions in SWMP are needed to fully ascertain performance and assess the potential for biotic effects in downstream taxa
On National Defence: A Contemporary Evaluation of the Canadian Armed Forces
Get PDFThis article examines the contemporary history of the Department of National Defence (DND) and the Canadian Armed Forces (CAF) from peacekeeping to the most recent update to Canadian defence policy, highlighting their historical roles and contemporary challenges. It discusses the evolving purpose of the CAF, which has shifted from conventional defence to supporting and reinforcing a western-led international order. It explores issues such as defence spending, procurement challenges, peacekeeping endeavors, veterans’ support, diversity and inclusion within the CAF. Moreover, it explores emerging threats in cyber, space and Arctic domains, including the rise of artificial intelligence threats, and emphasises the need for Canada to adapt its defence strategies accordingly. Specific focus is given to changes in Canadian defence policy in Strong, Secure, Engaged (SSE) released in 2017, and Our North, Strong and Free released in 2024. Ultimately, the article offers a critical assessment of Canada’s military role in the context of evolving global challenges and societal values, highlighting the recent policy shift towards expanding national and international defence
The Atiyah-Hitchin-Singer Theorem and an 8-dimensional generalization
Get PDFThe Atiyah-Hitchin-Singer theorem states that the twistor almost complex structure on a certain S2 bundle over an oriented Riemannian 4-manifold (M, g) is integrable if and only if the Weyl curvature tensor of g is self-dual. These ideas were developed by Roger Penrose connecting 4-dimensional Riemannian geometry with complex geometry. We present a new approach to the Atiyah-Hitchin-Singer theorem using horizontal lifts and their respective flows, cross products and the quaternions to show that the Nijenhuis tensor vanishes if and only if the Weyl curvature tensor of g is anti-self-dual. An eight dimensional generalization is presented when the manifold is R8