A simple, inexpensive in situ method for assessing acute toxicity of effluents to fish

Test chambers for conducting in situ fish bioassays were constructed from 81. polyethylene bottles. Yearling fathead minnows (Pimephales promelas) and young-of-the-year bluegill (Lepomis macrochirus) demonstrated greater than 50% survival in the chambers after 65 days of exposure in a reservoir, river and creek. Fathead minnow survival was substantially greater than that of bluegils. The chambers provide a simple, inexpensive, sensitive technique to screen effluents for toxicity.     

Application of in situ dialysis cultures in studies of phytotoxicity of north sea crude oils

The three marine planktonic diatoms Skeletonema costatum (clone Skel-5), Thalassiosira pseudonana (clone 3H) and Phaeodactylum tricornutum (clone Pheo) were grown in dialysis cultures in outdoor tanks exposed to seawater extracts of Ekofisk and Statfjord crude oils and to sea water collected below an artificial oil spill with Statfjord crude oil at Haltenbanken.The effects on growth rate and photosynthetic capacity were similar to those observed in laboratory batch cultures, and so was the difference in sensitivity among the algae, with Skeletonema being the most sensitive species.The in situ dialysis culture technique served well as a link between the laboratory and the field situations, and may be used as a monitor of phytotoxic effects in an oil spill situation.     

The unreliability of the kinetic approach to measuring bacterial mineralization activities at low in situ temperatures in an acidic aquatic environment

This paper concerns the kinetic approach to measuring glucose mineralization by planktonic bacteria in Whitson Lake, a moderately acidic lake. For all three samplings, plots of the amount of glucose mineralized vs time of incubation were linear at both high and low concentrations of added glucose. When sample water buffered around the in situ pH was used in these time studies, linear relationships were again evident, but there was a reduction in the rates of glucose mineralization activity. Nevertheless, the kinetic approach usually failed to generate the Michaelis—Menten response at the necessary level of statistical significance to justify calculations of turnover times and V_max values. And, buffering the pH around the in situ pH did not insure that the Michaelis—Menten response would be obtained.These observations are discussed in the light of our earlier observations involving an extremely acid-stressed lake.     

Orientation and magnitude of in situ stress to 6.5 km depth in the Baltic Shield

Understanding the state of stress in the earth is important for a broad range of engineering and geological problems. To obtain the state of stress in boreholes where conditions are such that conventional stress measurement techniques are impossible, we have used recent developments in the analysis of compressive and tensile wellbore failure in an integrated stress measurement strategy, involving also direct measurement of the least principal stress. The analysis is carried out in the two deep boreholes in the Siljan Ring area of the Baltic Shield. The Gravberg-1 borehole reached 6779 m true vertical depth (TVD) in the Siljan region, central Sweden, and the Stenberg-1 borehole, drilled 10 km to the south of Gravberg-1, was completed at 6529 m TVD. Analysis of vertical, drilling-induced tensile fractures in the nondeviating part of the Gravberg-1 well indicated that one principal stress is vertical and thus could be calculated from density estimates. Borehole breakouts and tensile fractures indicated that the average direction of the maximum horizontal stress, S_H, is N72°W±7° in Gravberg-1 and N53°W±9° in the Stenberg-1 well. The direction of S_H is on average very stable in both wells. Lower bound limits on the magnitude of the minimum horizontal stress, S_h, in the Gravberg-1 well were obtained from controlled and uncontrolled hydraulic fracturing and formation integrity tests. At 5 km depth in the Gravberg-1 borehole the minimum horizontal stress is approximately two-thirds of the vertical stress. We estimated the magnitude of the maximum horizontal stress in Gravberg-1 on the basis of drilling-induced tensile fractures identified in the borehole. S_H was estimated by calculating the stress at the borehole wall necessary to cause tensile failure of the formation, incorporating our lower bound S_h estimates, corrections for the cooling of the wellbore by drilling fluids and differential fluid pressures. Our results indicate a strike-slip faulting regime in the Siljan area and that the state of stress is in frictional equilibrium with a coefficient of friction in the range 0.5 to 0.6.     

The use of Bacillus thuringiensis var. israelensis to control the nuisance fly Sylvicola fenestralis (Anisopodidae) in sewage filter beds

The effectiveness of using the microbial insecticide Bacillus thuringiensis var. israelensis (Bti) to control the nuisance fly Sylvicola fenestralis at Rossendale Sewage Works, Lancashire, was investigated. Following a provisional trial in 1987, the whole Works (28 filter beds) was treated with a two-stage application of Bti in 1988; the first application in late April was separated from the second in late May by about half the length of the Sylvicola life-cycle. The Bti treatment was timed to reduce fly nuisance in June, the month when most complaints (71%) had been received. For each application, 0.161. of the Bti preparation, containing nearly 10¹⁰ spores·cm⁻³, was applied per square metre of bed surface. An 80 and 98% kill of Sylvicola larvae was recorded following the first and second applications respectively. The lower kill achieved by the first application was believed to be due to insufficient mixing of the Bti with the settled sewage prior to dosing. Nuisance caused by the flies was considerably reduced; there were no complaints from the public during June, although a few were received in late July, early August. Sewage purification efficiency was not affected by Bti treatment. The maximum concentration of Bti spores in the Works' effluent was 7 × 10⁴ spores·cm⁻³. This concentration did not appear to affect the already impoverished macro-invertebrate fauna of the receiving river.     

Cryptosporidium and Giardia detection in water bodies of Galicia, Spain

The objective of this study was to determine the mean concentration (per litre) of Cryptosporidium oocysts and Giardia cysts in recreational river areas (n = 28), drinking water treatments plants (DWTPs; n = 52) and wastewater treatment plants (WWTPs; n = 50) in Galicia (NW Spain). Water samples from rivers and from the influent (50–100 l) and the treated effluent (100 l) of the water plants were filtered using Filta-Max filters (IDEXX Laboratories, Inc., Westbrook, ME, USA). A total of 232 samples were processed and the (oo)cysts were concentrated, clarified by IMS and then detected by IFAT. The viability was determined by applying fluorogenic vital dye (PI).In the recreational areas, infective forms of Cryptosporidium and Giardia were detected in 16 (57.1%; 1–60 oocysts per litre) and 17 (60.7%; 1–160 cysts per litre) samples, respectively. In the water flowing into the water treatment plants, oocysts were detected in 21 DWTPs (40.4%; 1–13 oocysts per litre) and cysts were observed in 22 DWTPs (42.3%; 1–7 cysts per litre). In the effluents from the treatment plants, Cryptosporidium oocysts and Giardia cysts were identified in 17 DWTPs (32.7%; 1–4 oocysts per litre) and in 19 DWTPs (36.5%; 1–5 cysts per litre), respectively. The highest concentrations of (oo)cysts were found in the WWTPs; specifically, oocysts were detected in 29 (58.0%; 1–80 oocysts per litre) and cysts in 49 (98.0%; 2–14.400 cysts per litre) WWTP effluents. Cryptosporidium and Giardia were detected in 32 (64.0%; 1–120 oocysts per litre) and 48 (96.0%; 2–6.000 cysts per litre) WWTP effluents, respectively. The percentage viability of the (oo)cysts ranged between 90.0% and 95.0%. In all samples analysed. Moreover, it was found that the effluents from coastal WWTPs were discharged directly into the sea, while inland WWTPs were discharged directly into rivers. The concentrations of both enteropathogens detected in effluents from WWTPs therefore represent a significant risk to human and animal health.These results demonstrate the wide distribution of Cryptosporidium and Giardia in the environment, the ineffectiveness of treatments in DWTPs and WWTPs in reducing/inactivating both protozoa and the need to monitor the presence, viability and infectivity of Cryptosporidium and Giardia in water bodies. In conclusion, the findings suggest the need for better monitoring of water quality and identification of sources of contamination.     

In situ persistence of indicator bacteria in streams polluted with acid mine drainage

Persistence of indicator organisms (total coliforms, fecal coliforms, and fecal streptococci) associated with natural samples of raw sewage was studied following in situ exposure to five aquatic environments. Three of these streams contained significant amounts of acid mine water (AMW) while the other two were relatively uncontaminated. Indicator organisms were rapidly killed upon exposure to the acid mine systems, whereas little reduction in numbers was observed in the uncontaminated streams. Seasonal changes affected survival of indicators as reflected by prolonged persistence at colder in situ water temperatures. The fecal coliform group was most susceptible to the AMW stress, while the fecal streptococci were most persistent. An enrichment technique resulted in substantially enhanced recovery of certain species of sublethally injured survivors of acid stress. Enrichment was particularly beneficial for recovery of AMW-injured fecal coliforms. Relatively little improvement in recovery of fecal streptococci was afforded by the enrichment technique.     

Life history responses of Daphnia magna feeding on toxic Microcystis aeruginosa alone and mixed with a mixotrophic Poterioochromonas species

The toxic effects of a mixotrophic golden alga (Poterioochromonas sp. strain ZX1) and a cyanobacterium Microcystis aeruginosa grazed by Poterioochromonas to a cladoceran were investigated through life history experiments using Daphnia magna. Poterioochromonas cultured in two ways (fed M. aeruginosa in an inorganic medium or grown in an organic medium) both induced starvation-like effects on D. magna, indicating that Poterioochromonas is neither acutely toxic nor a good food for D. magna. Despite a microcystin-LR content of 10⁻⁸ μg cell⁻¹ in M. aeruginosa, no toxins were accumulated in Poterioochromonas fed the cyanobacterium. The toxic effect of M. aeruginosa to D. magna was significantly reduced in the presence of Poterioochromonas, which may be performed in two ways: decrease M. aeruginosa cells ingestion of D. magna by grazing on M. aeruginosa; and decrease the toxicity of the medium by degrading the toxins released by M. aeruginosa. This study provides new information on the interactions between a cyanobacterium and its grazer under laboratory conditions and may increase our understanding of the ecological significance of such interactions in the aquatic food webs.     

TheGammarus: Asellus ratio as an index of organic pollution

Macroinvertebrate populations includingGammarus pulex andAsellus aquaticus were surveyed at riffle sites on four lowland rivers, i.e. the Rivers Adur and Ouse and the Chess Stream, Sussex, and the Eridge Stream, Kent. Sites were situated both upstream and downstream of sewage treatment works. Macroinvertebrates were collected using a Surber sampler and at some sites the water analysed for the main chemical constituents.Poor water quality is characteristically associated with low biotic scores and in this respect theGammarus : Asellus ratio applied to riffle data corresponded with the Chandler Biotic Score Index and the Extended Trent Biotic Index. TheGammarus : Asellus ratio showed the closest correlations with concentrations of BOD, ammonia-nitrogen (NH₃-N), nitrite-nitrogen (NO₂-N) and phosphate-phosphorus (PO₄-P) being sensitive to changes in water quality brought about by organic enrichment in the four rivers investigated.It is proposed that theGammarus : Asellus ratio may provide a simple biological tool which could be used by anglers and other non-professional river users to routinely monitor water quality.     

Flow-through in situ metabolimeter for monitoring oxygen consumption, production and diffusion in natural waters

A flow-through in situ metabolimeter was developed for the direct measurement and monitoring of oxygen production (primary production), consumption and diffusion in highly eutrophic natural waters. This in situ open measuring system permit to reduce the disadvantages of the closed dark-light bottle procedure and of the Winberg-Odum's diel oxygen curve methods.     

An in situ method to compare the potential for periphyton productivity of lotic habitats

A simple field method for measuring relative net productivity in flowing waters is described. To assess its sensitivity and practicality, the eutrophication potential of a tertiary sewage treatment plant effluent was assayed on the Fort River of Amherst, Massachusetts. Two sets of three 10 m lexan tubes (1.25 cm i.d.) were anchored to the river bed 100 m upstream and downstream from the sewage plant outfall. Data collection began following a 2 week colonization period for the periphyton community. Substrate primary productivity (mg O₂ min⁻¹) was determined by subtracting inflow dissolved oxygen concentrations from these levels at the discharge ends of each tube and multiplying the difference by the flow rate. The downstream tubes demonstrated an enhanced response at a 0.01 level of significance to an increment of 0.005 and 0.1 ppm of phosphorous and nitrogen respectively. Data analysis revealed a highly significant regression of the net productivity on stream flow which was adjusted for by an analysis of covariance. The productivity of the downstream station was distinctly higher (0.4522 mg O₂ min⁻¹) then the value of the upstream station (0.2584 mg O₂ min⁻¹). The protocol thus affords a biological summation of the sewage effluent through comparison with the control station replicates.     

Use of an in situ artificial substrate for biological accumulation and monitoring of aqueous trace metals a preliminary field investigation

A preliminary field study was undertaken to investigate the use of attached periphyton on an artificial substrate as a water column composite sampler for trace metals. Spatial and temporal trends are presented of trace metal biological accumulation terms of the substrate placement in the vicinity of a synthetic fiber chemical manufacturing plant. Seasonal distribution and biological accumulation of antimony, chromium, copper, mercury and zinc is discussed. Statistical analysis of metal accumulated as a function of substrate placement, showed significantly higher levels of chromium for the discharge station compared to the reference stations. In contrast sediment analysis of the discharge station showed only slightly higher levels of zinc and no significant chromium accumulation when compared to a upriver reference station.     

A modified fluorometric method for measurement of lignin sulfonates and its in situ application in natural waters

A modified fluorometric method for the determination of lignin sulfonate in natural water is described. The optimum wavelengths for excitation and emission were found at 285 and 405 nm respectively. A low interference from natural compounds, especially humic substances, has been attained. The application of the method to a filter fluorometer for in situ measurements is described together with some test results.     

Concentration-dependent response of estrone-degrading bacterial community in activated sludge analyzed by microautoradiography-fluorescence in situ hybridization

Inefficient removal of estrone (E1) in wastewater treatment plants (WWTPs) causes feminizing effects in male aquatic creatures. As E1 is mainly removed by biodegradation, investigation of E1 degradation is important to determine better removal strategies. Using microautoradiography-fluorescence in situ hybridization (MAR-FISH), we demonstrated that the structures of [³H]E1-incorporating bacterial communities were different at different E1 concentrations applied to activated sludge. At 200 μg/L E1, almost all [³H]E1-incorporating cells were associated with either Betaproteobacteria or Gammaproteobacteria (60% and 40% of MAR (+) cells, respectively). The proportion of Betaproteobacteria and Gammaproteobacteria in the total number of [³H]E1-incorporating cells decreased as the concentration of E1 decreased. In contrast, the proportion of Alphaproteobacteria in the total number of [³H]E1-incorporating cells increased as the concentrations of E1 decreased. At the lowest applied concentration (540 ng/L), almost all the [³H]E1-incorporating cells were Alphaproteobacteria (96%). The results of MAR-FISH applied to sludge samples collected from various plant locations and activated sludge processes, and during different seasons also demonstrated the high contribution of Alphaproteobacteria to the entire E1-degrading bacterial community (50.4 ± 11% of the total number of [³H]E1-incorporating cells) at 1 μg/L E1. Since the E1 concentration in domestic wastewater is at sub-μg/L levels, the key E1 degraders in activated sludge of domestic WWTPs are probably be Alphaproteobacteria. All [³H]E1-incorporating Alphaproteobacteria were hybridized with probe ALF968. Few MAR (+) cells were Sphingomonadales. An E1-degrading bacterial community at low E1 concentration appeared to consist of diverse bacterial groups of Alphaproteobacteria. This study suggested that substrate concentration is an essential factor for revealing E1-degrading bacteria in complex communities.     

Light induced Nitrosomonas inhibition

The purpose of this study was to evaluate and verify the impact of light exposure on an enriched Nitrosomonas culture. Resting cells maintained under aerobic conditions without an exogenous ammonium-nitrogen source were fully inhibited within a 10 min period of ambient light contact (i.e. fluorescent and indirect natural room light). These cells were, however, protected against this inhibitive phenomenon during active respiration periods and during anoxic exposure conditions. Recovery, albiet partial, from such light induced inhibition was initiated after a “dark” contact period of approx. 2.5–3 h without exogenous ammonium presence. Research involving enriched or pure Nitrosomonas cultures (e.g. batch bioassay testing) should consequently be completed under environmental conditions designed to obviate this problem.     

Estimation of thermal conductivity and its spatial variability in igneous rocks from in situ density logging

Characterisation of thermal conductivity of rock and its spatial variability by laboratory measurements is costly and time-consuming. There is an incentive to find more cost-effective and rapid methods. A new empirical relationship between density and thermal conductivity for igneous rocks has been found. This paper explains that the relationship is based on the rock forming processes which in turn generate typical mineral compositions. Based on this relationship, thermal conductivity can be estimated from geophysical density loggings. Experience has shown that this indirect method of determining the thermal conductivity can be used to characterise the spatial variability of thermal conductivity for certain rock types. The spatial data can be used in the modelling of thermal rock domains. Applications of the statistical relationship are presented and illustrative examples are given of how spatial variability of thermal conductivity can be estimated, based on the site investigations in a crystalline bedrock environment in Sweden. Possible deficiencies of the method are identified, such as uncertainties associated with different rock forming minerals. Methods of improvement are also discussed.