From ceginfo@u.washington.edu Wed Jul 5 08:31:32 2000 Received: from jason03.u.washington.edu (root@jason03.u.washington.edu [140.142.77.10]) by lists.u.washington.edu (8.9.3+UW00.05/8.9.3+UW99.09) with ESMTP id IAA123790 for ; Wed, 5 Jul 2000 08:31:31 -0700 Received: from homer23.u.washington.edu (ceginfo@homer23.u.washington.edu [140.142.77.3]) by jason03.u.washington.edu (8.9.3+UW00.05/8.9.3+UW00.01) with ESMTP id IAA36416; Wed, 5 Jul 2000 08:31:28 -0700 Received: from localhost (ceginfo@localhost) by homer23.u.washington.edu (8.9.3+UW00.05/8.9.3+UW99.09) with ESMTP id IAA84214; Wed, 5 Jul 2000 08:31:27 -0700 Date: Wed, 5 Jul 2000 08:31:25 -0700 (PDT) From: Civil and Environmental Engineering To: cegrads@u.washington.edu, faculty@ce.washington.edu, jacoby@seattleu.edu, jonathan.frodge@u.washington.edu Subject: MSE Defense for Bernadette Kenworthy Message-ID: MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=X-UNKNOWN Content-Transfer-Encoding: QUOTED-PRINTABLE The final examination for the MSE degreee for Bernadette Kenworthy will be held on Tuesday, July 11, 2000 at 9:30 a.m. in More 230. Mass occurrences (=93blooms=94) of cyanobacteria occur in freshwater, estua= rine,=20 and marine ecosystems throughout the world. Cyanobacterial blooms are a=20 manifestation of the accelerating nutrient, particularly phosphorus,=20 enrichment of aquatic systems. These blooms often create unsightly surface= =20 scums, decreased water column transparency, unpalatable drinking water, and= =20 odors. Some species of cyanobacteria also produce toxic compounds that hav= e=20 been implicated in livestock, wildlife, and pet fatalities as well as=20 several human poisonings worldwide. Furthermore, some of these toxins are= =20 known tumor promoters and have been associated with the high rates of=20 primary liver cancer in China. A toxic cyanobacterial bloom in Lake=20 Sammamish occurred in September-October 1997 after 8.3 cm of rain fell over= =20 a five day period. Microcystin, the toxin produced by the cyanobacterium= =20 Microcystis aeruginosa may have responsible for the death of a pet dog and= =20 the reported illness of young children who swam in the lake. Because the=20 lake serves as both a popular location for family residences and aquatic=20 recreation, future blooms greatly concern the local community. This study= =20 aimed to develop a better understanding of environmental conditions and=20 cyanobacterial activity in the lake that may promote toxic cyanobacterial= =20 blooms. A second objective was to assess whether bloom proliferation was= =20 due to runoff of nutrients from the watershed (external loading) or from=20 migration of dormant cyanobacteria from the nutrient-rich sediments into th= e=20 water column (internal loading). To investigate the role of=20 sediment-to-water migration of Microcystis to the formation of toxic blooms= ,=20 migration traps were placed at two locations in the lake during June-Octobe= r=20 1999 and samples of migrating phytoplankton were collected over 7-day=20 intervals. In addition, environmental factors (e.g., nutrients,=20 chlorophyll, dissolved oxygen, and temperature) were measured concurrent=20 with the migration study. Analysis of microcystins using an enzyme-linked= =20 immunosorbent assay revealed a toxin-producing bloom during late August and= =20 early September of 1999 despite the absence of visible cyanobacterial=20 biomass. Microcystin concentrations ranged between 0.19=963.8 ug/L through= out=20 the lake and at all depths with the exception of the boat launch where=20 concentrations reached 43 ug/L. Comparison of the conditions associated=20 with both the 1997 and 1999 blooms indicate that blooms of toxin-producing= =20 cyanobacteria appear to be associated with a stable water column (RTRM =3D= =20 255), increased surface total phosphorus concentrations (> 10 ug/L), warm= =20 surface temperatures (> 22C), high total nitrogen to phosphorus ratios (>= =20 30), and increased water column transparency (up to ~5.5m). Migration=20 results indicated that migration of the cyanobacteria, Microcystis and=20 Anabaena, occurred in both the deep and shallow portions of the lake. =20 Microcystis dominated (89-99%) the migrating cyanobacteria with greater=20 migration from the shallow region. External loading of nutrients due to th= e=20 large rainfall preceding the 1997 toxin-producing bloom may have provided= =20 the nutrients needed to fuel that bloom. However, a toxin-producing bloom= =20 occurred in 1999 despite the lack of rain and subsequent external runoff. = =20 The migration of cyanobacteria from the nutrient-rich sediments instead of= =20 the external runoff of nutrients may have fueled the summer 1999 bloom. Room Reservation #22395 Dr. Jean Jacoby, Chair Dr. Eugene B. Welch Dr. Michael T. Brett Dr. Jonathan Frodge .