ARTEMIA POPULATIONS IN MODERN CONDITIONS OF SALT LAKES OF SOUTH-EASTERN KAZAKHSTAN

Assessment of the state of a valuable bioresource of salt lakes - artemia crustacean and its cysts - has never been done before for the southern regions of the Republic of Kazakhstan. The purpose of the study is to characterize the crustacean populations in the south east of Kazakhstan, in three Ray Lakes of the semi-desert Balkhash area and in the piedmont Tuzkol Lake (the Almaty Region). Water mineralization in the Ray Lakes No.1 and No.2 can be called brines (71.5-153.9 g/dm3); Lake No.3 has salty water (16.5-26.2 g/dm3). The amount of ions in waters of Tuzkol Lake did not exceed 46.7 and 52.8 g/dm3 in spring and summer 2017. Its mineralization can reach 160 g/dm3 in October and 278.8 g/dm3 during low-water summer season. The water in the lakes contains sodium chloride, type I or II. It is characterized by a low Na+ : K+ ion ratio in the water in different seasons (4.4-11.2). In the Ray Lakes No.1 and No.2 and Tuzkol Lake the crustacean is represented by parthenogenetic race. No artemia has been found in Ray Lake No.3 against massive development of other zooplankters. Artemia biomass in the Ray Lakes is registered from low to very high (1.9-64.5 g/m3), but the cyst concentration was low (0.1-18.0 thousand specimens/m3). Tuzkol Lake has a very high crustacean production in the beginning and in the end of the vegetation period (71.25-99.75 g/m3). Maximal cyst density was registered there in October (525.000 specimens/m3) and under extreme water salinity (110.000 specimens/m3). Tuzkol Lake is recommended for artemia cyst fishery. The Ray Lakes can be used as a crustacean biofund for inoculation into the water bodies of the southern region.

Incorporating method recovery uncertainties in stochastic estimates of raw water protozoan concentrations for QMRA

The impact of incorporating recovery data on protozoan concentration estimates was investigated for Cryptosporidium and Giardia using a large dataset (n=99) of [oo]cyst assay results with paired recovery estimates. Stochastic [oo]cyst concentration was estimated using three approaches: I – no availability/consideration of recovery, II – limited recovery data, where sample recovery was considered as an independent random variable, and III – every [oo]cyst assay result was adjusted for a concurrently derived recovery estimate. Critically, Approach I underestimated [oo]cyst concentrations by about 100% compared to Approaches II and III, which were similar. The impact of dataset size on statistical uncertainty about the concentration estimate for Approach II was investigated; little improvement in parameter uncertainty was achieved beyond n=20. It is suggested that recovery data be incorporated into source water concentration estimates, especially when used to infer health risks to consumers, so as not to underestimate the risk. Where none is available, conservatively low recoveries should be assumed. When designing monitoring programmes, recovery data should be collected as a pair with [oo]cyst count data for an initial period at least, so that site-specific relationships between those parameters may be ascertained and incorporated into source water concentration estimates.

Giardia sp. cysts and Cryptosporidium spp. oocysts dynamics in southeast Brazil: occurrence in surface water and removal in water treatment processes

Raw water and filtered effluent of three drinking water treatment plants (WTP) at a town in Minas Gerais State, southeast Brazil, were monitored over a one-year period for Giardia, Cryptosporidium, microbiological and physical-chemical water quality indicators. High densities of Giardia and Cryptosporidium were detected in two source waters, ranging from 2.0–140 cysts/L and 4.0–510 oocysts/L. Giardia and Cryptosporidium (oo)cyst concentration was not consistently associated with most of the parameters analysed, turbidity being the most promising indicator. It also seems that Giardia and Cryptosporidium concentration was influenced by rainfall. Giardia cysts and Cryptosporidium oocysts were significantly associated in both waters, suggesting a similar pattern of occurrence and common contamination sources. In two of the three water treatment plants analyzed, Giardia and Cryptosporidium were detected in filtered effluents, also in high densities, ranging from 0.066 to 5.5 cysts/L and 0.066 to 13.2 oocysts/L, respectively. Statistical trials to associate protozoa and indicator removal failed in nearly all cases. Nevertheless, the results are interpreted as neither reaffirming nor negating the use of turbidity as a protozoa removal indicator.

Giardia muris Cyst Inactivation in Anaerobic Digester Sludge

Anaerobic sludge exposures conducted at 21.5°, 37°, and 50°C produced 99.9 % G. muris cyst inactivations in 15.1 days, 20.5 hrs, and 10.7 minutes, respectively. A comparison of 99.9 % G. muris cyst inactivation times with USEPA anaerobic digestion treatment standards for land applied sludges (in 40 CFR 257) indicated that compliance with the latter would readily achieve 99.9 % G. muris cyst inactivations. Percent cyst inactivation (% I) was defined in terms of cyst concentration and cyst excystation by the following equation: %I = (1- (C)EX)100, where ‘C' was the fraction of the original cyst concentration remaining after exposure and ‘EX' was the fraction of the remaining cysts that were able to excyst. The 99.9 % Giardia cyst inactivation treatment standard of the USEPA's Surface Water Treatment Rule was adopted as a Giardia-based treatment standard for land applied sludges.

Determining Giardiasis Prevalence by Examination of Sewage

Raw sewage samples were collected monthly for one year from 11 wastewater treatment plants located across the United States. Giardia cyst concentrations in the raw sewage were determined by direct count using criteria of size, shape and the presence of two or more internal morphological characteristics for identification. The data were adjusted based on percentage of industrial wastewater reported processed by each plant. Although differences in the adjusted annual geometric mean cyst concentrations were noted among the sites (the highest was 3750 cysts/L and the lowest was 683 cysts/L), there was no correlation of cyst concentration with geographical location as determined by either latitude or longitude. However, when the three southernmost sites were grouped and compared against the group of all remaining sites, there was a significant difference in the annual geometric mean cyst concentration with the southernmost sites being higher. There was no significant association of geometric mean cyst concentration with size of the wastewater treatment plant as represented by mean daily flow. Attempts were made to obtain and correlate giardiasis cases with the monthly cyst levels at each of the sites. Due to reporting problems, low number of cases or unavailability of data, case information was deemed usable for only four of the 11 sites. A significant positive correlation with cases in the community was found at one site. Lack of correlation at other sites was believed to be due to deficiencies in case reporting. The results suggest that sewage examination may be useful for surveillance of Giardia infections in the community.

Spatial and Temporal Variability of Dinoflagellate Cyst Abundance in a Tidal Estuary

A study of dinoflagellate cysts was made in an estuary near Plymouth, England for 1 yr. The data show that the cysts were most concentrated in sediments near the entrance of the estuary (3000 cysts (mL∙flocculant−1)) and less concentrated upstream (< 500 cysts (mL∙flocculant−1)). Dinoflagellate cysts were observed in 99% of the plankton samples with an average concentration of 9.2 cysts∙L−1. Thirty percent of the variance in planktonic cyst concentration was associated with tidal range, wind stress, and river flow. The potential for inoculation of nearshore dinoflagellate populations by estuarine populations is discussed.Key words: benthic resting cyst, dinoflagellate, estuary, frontal convergence, sediment trap, spring tides, turbulence

Heterodera schachtii (Schmidt) and Soil Acidity

1. The possibility of correlating the acidity of the soil with the distribution of cysts of Heterodera schachtii is investigated by a colorimetric method of hydrogen ion determination. The variety of this eelworm which infests potatoes is alone considered, the material being derived from South Lincolnshire—in particular from Kirton and the district around Boston. The samples, general notes and cyst-concentration data are due to Morgan, to whom the writer is greatly indebted.2. A brief account of the life-history of H. schachtii is given, and also:3. A note on the theoretical aspect of hydrogen ions and of the colorimetric methods for determining their concentrations.4. The technique involved is fully discussed, and after various tests is standardized as follows : 2 grams of dry, finely-sieved soil are shaken up with 10 c.c. of twice-distilled water for ¼ hour. The mixture is centrifuged for 5 minutes and diluted with water in the ratio 1:9. A suitable indicator is added, aeration of the solution follows, and the pH-value is read by comparison with indicator-standards in a Walpole Comparator.It is pointed out that at most the results give the pH-value of the solutions. The pH-value of the soil itself, in situ, is not determined, so that the results are only of relational value.