USING A CHOICE MODELLING APPROACH FOR CUSTOMER SERVICE STANDARDS IN URBAN WATER1

ABSTRACT: A series of reforms in the water industry in Australia has created a demand from the industry and regulators for objective methodologies to evaluate incremental changes in the customer service standards. In this paper, the use of choice modeling for estimating implicit prices associated with urban water supply attributes is explored. Results from multinomial logit (MNL) and random parameters logit (RPL) models show that increases in annual water bills and the frequency of future interruptions were the most important attributes. Implicit price confidence intervals based on the best models suggest that people are willing to pay positive amounts to achieve a water supply that is less frequently interrupted. The provision of alternative water supplies during an interruption and notification of the interruption were found to be unimportant to respondents. Choice modeling proved to be a useful technique and provided the industry and regulators with additional information for standard setting.     

Modelling trace metal partitioning in forest floors of northern soils near metal smelters

Trace metal (TM) mobility and toxicity varies with changing soil conditions. Geochemical models can account for the influence of soil characteristics on TM behaviour. We tested the effectiveness of the Stockholm humic model (SHM), and the NICA-Donnan model (NDM) to estimate partitioning coefficients (logKd) in 26 forest floor horizons of podzolic soils enriched in trace metals from deposition by metal smelters. We wanted to know if a consistent approach could be applied to model metal partitioning in forest floors without optimizing each individual soil. When optimized, the SHM reproduced the partitioning of Cd, Cu and Zn but not Pb. It was necessary to revise the affinity constants for the NDM to simultaneously simulate the partitioning of the four metals. Revised affinity constants for the NDM model based on a fixed definition of soil organic carbon, i.e., a fixed ratio of fulvic and humic acids per unit carbon, reproduced metal partitioning more effectively in an independent data set of 16 soils than the use of generic affinity constants available for these models. From the perspective of the applicability of these models to risk assessment, this result suggests geochemical models using affinity constants that have been verified and/or modified against multiple soils from a region can provide good estimates of metal partitioning on a regional scale.     

Feeding behaviour of the sea cucumber <Emphasis Type="Italic">Cucumaria frondosa</Emphasis> (Echinodermata: Holothuroidea) in the laboratory and the field: relationships between tentacle insertion rate,flow speed,and ingestion

The sea cucumber, Cucumaria frondosa, is a benthic suspension feeder that captures food particles on its tentacles and then inserts them into its mouth one at a time. Previous studies have suggested that tentacle insertion rate (TIR) could be a useful indicator of food intake. The present study determined whether flow velocity affects TIR and whether TIR is a good indicator of ingestion. Video observations of sea cucumbers in Passamaquoddy Bay (45°01.70N, 66°55.74W) in August 1995 showed that TIRs increased with velocities up to 55 cm s⁻¹ and decreased steadily at flows above that up to 130 cm s⁻¹. In October 2006, laboratory flume studies were carried out on specimens collected from the same site in the previous August. Temperature and salinity (12°C and 32) in the flume were the same as in the field at the time of collection. There was high individual variation in feeding behavior at free-stream velocities of 4–40 cm s⁻¹ and TIR was independent of flow. As the number of tentacle insertions increased in the flume experiments, the amount of chloropigments in the digestive tracts of the sea cucumbers also increased. This suggests that TIR, which can be measured non-intrusively using remote video techniques, could be a good indicator of feeding behavior and ingestion in C. frondosa.     

Influence of temperature and food availability on the ecological energetics of the giant scallop Placopecten magellanicus

Scallops (Placopecten magellanicus) were collected in 1981–1983 from two water depths at a location in Newfoundland, Canada, where temperature and food conditions associated with shallower water have been shown to be more favourable for somatic growth and gamete production. To gain insight into the seasonal energy balance for this species, metabolic and clearance rates were measured monthly under ambient temperature conditions and natural seston levels. Stereological techniques were used to determine the gamete volume fraction in the gonad in order to establish the annual reporductive cycle. The less favourable conditions associated with deeper water were relfected in reduced rates of gamete development, but the diameter of spawned eggs and the timing of spawning appeared unaffected by poorer conditions in the natural environment. Estimates of scope for growth were low or negative during the winter, but consistently high during the spring bloom, corresponding to a period of rapid gamete maturation. Somatic weight declined in both populations as gamete development proceeded but increased again during periods of low gametogenic activity, suggesting a close relationship between energy available for growth and the reproductive cycle. Oxygen uptake and clearance rate varied seasonally in relation to ambient temperature and food conditions, all of which appeared to be interrelated in a complex fashion with the energy demands of gametogenesis.     

Age determination of the soft-shell clam Mya arenaria using shell internal growth lines

Shells of known-age Mya arenaria have revealed an internal annual growth pattern in this bivalve. The number of external growth rings on the shell exterior does not correspond to the age of the clams. This study provides an alternative method to using external annual rings for age determination. The internal growth lines are visible in thin sections when the shells are cut from the umbo to the ventral margin. The lines are formed by late spring of each year prior to spawning and are probably in response to decreased winter growth. When the 7 year olds were examined it was difficult to distinguish the most recent growth line and the inner shell layer. This could result in ages being underestimated. This annual pattern of internal growth lines could be useful to biologists and paleoecologists engaged in population studies.     

Lipid composition of eggs and adductor muscle in giant scallops (Placopecten magellanicus) from different habitats

Scallops (Placopecten magellanicus Gmelin) were collected during August 1989 from shallow water (10 m) and deep water (31 m) habitats at Sunnyside, Trinity Bay, Newfoundland, to compare the lipid composition of eggs and adductor muscle tissue. Less favorable food levels and lower temperature conditions associated with deeper water have previously been shown to produce slower growth and reduced fecundity in individuals from this habitat. Triacylglycerol reserves consistently accounted for 60% of the total lipids present in both groups. The total lipid content of the eggs and the composition of their triacylglycerol fatty acid pools were similar in shallow water and deep water scallops, indicating very little if any nutritional difference between the two groups. Relative to their counterparts from shallow water, individuals from deeper water contained higher proportions of docosahexaenoic acid [22:6(n-3)] in the egg phospholipids and higher levels of 24-methylenecholesterol (a phytosterol commonly found in diatoms) in the adductor muscle. Differences in fatty acid composition are interpreted as biochemical adjustments of cell membranes to increase membrane fluidity, thereby compensating for the lower temperatures prevailing at the greater depth.     

Long-term atmospheric deposition of current-use and banned pesticides in Atlantic Canada; 1980-2000

The occurrence of current-use and banned pesticides is reported in wet-precipitation collected from four sites across Atlantic Canada during the period 1980-2000. The most frequently detected compounds were alpha-HCH, gamma-HCH (lindane), chlorothalonil, pentachlorophenol, atrazine, and endosulfan. Median site concentrations varied between not-detected and 10.2 ng l(-1). Deposition of HCHs (hexachlorocyclohexane), chlorothalonil, and endosulfan at Kejimkujik (Keji) and Jackson, Nova Scotia, were generally similar. Significant spatial differences (p<0.05), however, were found for the HCH isomers and endosulfan at Keji and Gros Morne (Newfoundland and Labrador), areas geographically separated by the northern Gulf of St. Lawrence. Long-term deposition of alpha-HCH decreased (p<0.05) at both Keji (1980-2000) and Gros Morne (1994-2000), with half-lives of 5.9 and 4.5 y, respectively. A decreasing trend was also found for pentachlorophenol with a half-life of 4.9 y at Jackson. Significant negative trends (p<0.05) were observed for alpha-/gamma-HCH ratios during the study at Keji and Jackson, possibly reflecting changes in production and use patterns of technical HCH and lindane on a continental and perhaps hemispheric scale. Seasonal trends for alpha-HCH and gamma-HCH were found to vary over the 20-y study period at Keji, however, spatial trends were generally similar between sites. Seasonal trends were observed with peak deposition generally occurring during the growing period (spring-summer) for the HCHs, chlorothalonil, endosulfan, and atrazine. Bimodal seasonal trends were also observed for these compounds with the exception of endosulfan.     

Aluminum output fluxes from forest ecosystems in Europe: a regional assessment

Data from 89 forested catchments and plots across Europe were used to define empirical relationships between aluminum leaching and input fluxes of major ions, output fluxes of major ions, ecosystem parameters such as soil pH, and combinations of these. Forests that release dissolved Al to seepage or surface waters are located primarily in areas receiving the highest loading of acid rain, and the output flux of Al shows the highest correlations to the throughfall flux of inorganic nitrogen, the output fluxes of NO3-, H+, and SO4(2-), and the mineral soil pH. If the speciation of Al is taken to be Al3+ (an overestimate), Al is released in a nearly 1:1 molar charge ratio with the sum of NO3- and SO4(2-) in runoff or seepage water over a wide range of basepoor bedrock types and acid deposition across Europe. The empirical data point to a threshold range of N deposition of 80 to 150 mmolc N m(-2) yr(-1) and a (less clearly defined) range of S deposition of 100 to 200 mmolc SO4(-2) m(-2) yr(-1) above which Al released from forests exceeds 100 mmolc Al m(-2) yr(-1). Within this threshold range, the sites that release little or no dissolved Al are those that continue to assimilate input N and/or have high soil pH (>4.5).