WHITE, A. W., AND G . M. LEwns. 1982. Resting cysts of the toxic, red tide dinoflagellate Gonyaulav excavata in Bay of Fundy sediments. Can. J. Fish. Aquat. Sci. 39: 11$5 -1194.During the winter of 1980-198 1 sediment samples were coIlected from 1 15 stations throughout the southern Bay of Fundy to determine the distribution and abundance of Gsnynulax e.xcwvata resting cysts. An improved, semiquantitative method of cyst enumeration was developed for this purpose. Resting cysts of G . excavata were widely dispersed in the Bay, occurring both offshore and inshore, including the intertidal zone. The great majority of cysts occurred in a large, extremely rich deposit located offshore in the southwestern Bay of Fundy in a zone of fine brown mud at depths of 80-160 m. The location of this deposit was consistent with hydrographic and sedimentary processes in the Bay. Cyst concentrations ranged from 2000 to $000 cysts-cm--\wet sediment at many stations in the approximately 2000-km2 deposit. Mouse bioassay tests of cyst extracts (prepared by sonication or boiling) indicated that the cysts were toxic, containing 2-5 X kg saxitoxin (STX) equivalent per cyst -the same range as for 6. excavata motile cells in culture. Results support the view that the wintertime acquisition of G . excavata toxins by offshore and inshore molluscan shellfish is caused by ingestion of cysts. Results suggest that the offshore seed bed serves as the primary source of the motile cells which initiate the annual G . excavata bloom in the Bay of Fundy . WHITE, A. W., AND C. M. LEWIS. 1982. Resting cysts of the toxic, red tide dinoflagellate Gorzyalclax excavnm in Bay of Fundy sediments. Can. J. Fish. Aquat. Sci. 39: 1185 -1194.Au cours de l'hiver 1980-81, nous avons prClevC des Cchantillons de stdiment a 115 stations par tout le sud de la baie de Fundy dens le but de dkterminer la distribution et l'abondance de kystes de Gonyaukax excavata. A cette fin, une mithode semi-quantitative amCliorte de comptage des kystes a Ct6 mise au point. On a trouvk des kystes de G . excavata largement rtpartis dans la baie, tant au large que prts de la cdte, y compris la zone intertidale. La grande majorit6 des kystes se trouvent en un vaste dCpBt, tres riche, au large dans la partie sud-ouest de la baie, dans une zone de fine vase brune A des profondeurs de 80 ? I 168 m. E'ernplacement de ce d6gGt s'accorde avec les processus hydrographiques et skdimentaires de B a figion. La concentration des kystes se situe entre 2 000 et 8 000 kystes de sediment hurnide de nombreuxs stations dans le dCpdt,.qui mesure 2 000 km2. Des essais biologiques d'extraits de kystes (prkpaes par traitement B I'ultrason ou par Cbullition) indiquent que les kystes sont toxiques, contenant 2-5 X pg de saxitoxine (STX) par kyste -Ia m6me fourchette que pour les cellules mobiles en culture de 6. excavata. Ces rCsultats corroborent la thCorie que I'acquisition, en hiver, de toxines de G . excavata par des mollusques au large et prks de la c8te est due a I'ingestion de kystes. Ils donnent tgalement B...

A well-characterized exposure chamber is necessary to generate reproducible atmospheres for inhalation toxicology studies. The aim of the present study was to characterize a head-only exposure chamber for non-human primates. Aerosols containing bovine serum albumin (BSA) were used to characterize a 16-L dynamic airflow head-only exposure chamber. A 250-ml plastic bottle with a respirator attached located inside the chamber was used to simulate a breathing head. Chamber leak rate, mixing, and aerosol spatial distributions were quantified. The chamber concentration profile was measured at the chamber exhaust using an aerodynamic particle sizer. Aerosol spatial distribution was determined by collecting filter samples at several chamber locations. The particle size distribution was determined by collecting cascade impactor samples at several chamber locations. The estimated chamber leak rate was within standards suggested in the literature. The measured average aerosol residence time was similar to theoretical aerosol residence time, suggesting that the chamber was mixing well. Additionally, the average concentration measured at each of the sampling locations within the chamber was similar, and the within-run coefficients of variation (CV) across all sampling locations was similar to those reported in previously published studies, again suggesting that the aerosol concentration throughout the chamber was uniform. The particle size distribution was similar throughout the exposure chamber. Additionally, the BSA concentration and particle size distributions measured in the breathing zone of the simulated head were not significantly different from measurements made elsewhere in the chamber, suggesting that respiration does not affect the average aerosol concentration or particle size distribution at the mouth.

A pilot study in milwaukee, wis., assessed lead levels before and after water main replacement and led to a new sampling and communication protocol for addressing possible increased lead at the taps of customers with lead service lines.

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Instruments that simultaneously count and size individual particles can be used for analyzing raw‐water particulates, optimizing chemical dosages, measuring particulates in filter effluent, determining filter efficiency in terms of percent removal of particles, and many other applications. A single particle counter will not, however, be universally applicable to all of these circumstances. The type of particle counter required will be determined by the types of water samples to be analyzed and the ultimate use of the data. Commercially available particle counters differ in terms of operational principles as well as complexity, particle size range capabilities, concentration limits, resolution, data‐processing power, and physical installation requirements. Basic features of particle counters and a step‐by‐step approach for evaluating particle counter capabilities are discussed, along with installation considerations for water quality monitoring in discrete and on‐line sampling configurations.