The effect of chlorine and chlorine dioxide on pathogenic free‐living amoebae (PFLA) in simulated natural conditions: The presence of bacteria and organic matter

Bacteria and bovine faecal matter were introduced into cultures of pathogenic free‐living amoebae, with chlorine or chlorine dioxide. The bacteria and faeces were to simulate natural conditions for a more exacting test of disinfectant demand when compared to axenic conditions. Both chlorine and chlorine dioxide were effective disinfectants under all conditions tested. Axenically and monoxenically cultured amoebae were used, the latter exerted a greater disinfectant demand.     

Nitrate levels in subsurface waters of the Waimea Plain,Nelson

In 1969–72, nitrate determinations were made on waters from 122 wells on the Waimea Plain, Nelson, South Island, New Zealand. Four wells showed values above 30 mg NO3‐N/litre with a maximum of 50 mg/litre in one well, fifteen were in the 30–20 mg/litre range, forty‐six were between 20 mg and 10 mg/litre; fifty‐seven were below 10 mg/litre, and in only four wells was the nitrate concentration below 1.0 mg NO3‐N/litre. Where it entered the plain, the Wairoa River usually contained about 0.07 mg NO3‐N/litre, whereas the Waiiti River contained from 0.5 to 2.0 mg NO3‐N/litre.

Mapping of gradients of nitrate level indicated that these might contribute to aquifer definition and to sources of replenishing waters.     

Untersuchung von drei Grundwasserwerken auf Vorkommen von Acanthamoeben,Naeglerien und anderen freilebenden Amöben

Prevalence of Acanthamoebae, Naegleriae and Other Free-living Amoebae in the Course of Water Treatment in Three Well Waterworks Numerous species of free-living amoebae and other protozoa had been observed in the raw water of three representative waterworks with enriched well water. They were eliminated most effectively during the water treatment procedure. Acanthamoebae and Naegleriae including thermophilic strains of these genera could not be identified in any of the clear water samples. Acanthamoebae and Vannellae isolated from different samples exhibited repeatedly intracellular infections with bacteria of the genus Cytophaga. Their role as possible hosts of different pathogenic and non pathogenic bacteria like Legionella sp., Listeria sp., and Pseudomonas sp. is confirmed by this observation. As known from earlier findings in connection with the Acanthamoeba-Legionella model, it can be assumed, that bacteria multiplying in trophozoites or being enclosed in cysts are protected against high concentrations of chlorine and other biocides.     

Squid mandibles from the stomachs of sperm whales (physeter catodon l.) captured in the cook strait region of New Zealand

The lower mandibles of squid in the stomachs of two sperm whales examined at the Tory Channel whaling station in 1963–4 were separated into 11 types according to a system of grouping devised by the authors and based on a key drawn up by M. R. Clarke.