Bioassays leachates

Nine bioassays Leachates of immersed whole tires... 

Four bioassays Leachates from the drainage system of... 

Four bioassays Leachates from MSWI bottom ashes... 

Leaves from the five plants were combined and divided into two equal weight samples. One sample was leached in distilled water for 2 hours at a ratio of 15 gms leaf fresh weight to 100 ml water. The leaf leachate was decanted and used directly in the bioassay. The second sample was ground in a blendor with distilled water at a ratio of 1 gm leaf fresh weight to 100 ml water. After standing for 15 min, the mixture was filtered and the filtrate was used directly in the bioassay. 

The radish bioassay, shown in Figure 8, does not show the strong activity at weeks 3 through 5, and the leachate activity is significantly different from the extract only at week-1. 

Figure 7. Tomato root growth bioassay of water leachates and...

Figure 8. Radish root growth bioassay of water leachate and extract of D. illinoensis. (-) leachate (-----) leaf extract.

Ultimately, it is important to develop explant bioassays which can help quantify allelochemicals. This will require greater availability of purified active products. However, at this time, the explant systems can be used to show qualitative effects whether in crude extracts, leachates or from HPLC fractionation (17). Once target species effects are characterized, other bioassays which may be more sensitive could be used as well. 

Axenic cultures of dwarf spikerush (Eleocharis colorado-ensis) were established in 4 L aspirator bottles containing quartz sand and a synthetic culture medium. These were periodically drained and the effluent subjected to fractionation and bioassays. This crude leachate was passed through a C. cartridge to separate polar from nonpolar compounds. The nonpolar fraction was eluted from the cartridge with acetone and the solvent evaporated with gas. The polar fraction was lyophilized. Both... 

Bioassays. Four bioassays were developed to test the phytotoxic affect of spikerush leachate. Two assays involving target plants (hydrilla and sago pondweed) were tested at the explant level. Two additional assays were developed, one involving whole plants... 

Bioassays and in vitro human models can be used to characterize the toxicity of leachate integrating the biological effects of all its constituents, in contrast to chemical analyses ... 

Experiment 1. Bioassays with allelochemical aqueous leachate. 

Principle Phytotoxic effects of the aqueous leachate of an allelopathic plant can be tested in vitro bioassays. Test or target plants are placed in contact with 0.5 % aqueous leachate from the allelopathic plant. Germination and radicle growth can be monitored during time-course experiments (i.e. after 24,48 and 72 h of treatment), but in this chapter we will include only the results obtained after 72 h of treatment. 

Bioassays are performed under sterile conditions in a laminar flow hood. Tomato seeds are previously washed and disinfected with 1% sodium hypochlorite. Seeds are germinated in the Petri dishes containing the S. deppei aqueous leachate. For control, seeds are germinated in 1% agar. Twelve seeds are placed on each Petri dish and kept in the dark at 27°C in a growth chamber. For enzyme activities, 40-50 Petri dishes are used per treatment. Primary roots (radicles) are excised after 72 h, frozen in liquid nitrogen and kept at -70 °C until use. For root growth response, experiments... 

Two bioassays are employed to evaluate the effect of samples on terrestrial life forms. For gas samples, the plant stress ethylene test is presently recommended. This test is based on the well-known plant response to environmental stress release of elevated levels of ethylene (under normal conditions plants produce low levels of ethylene). The test is designed to expose plants to various levels of gaseous effluents under controlled conditions. The ethylene released during a set time period is then measured by gas chromatography to determine toxicity of the effluent. For liquid and solid samples, a soil microcosm test is employed. The sample is introduced on the surface of a 5 cm diameter by 5 cm deep plug of soil obtained from a representative ecosystem. Evolution of carbon dioxide, transport of calcium, and dissolved oxygen content of the leachate are the primary quantifying parameters. 

The aqueous extracts of roots and leaves, the leachates of aerial parts, aqueous extracts of soils and in some cases organics extracts of leaves, the essential oils, and Isolated pure compounds were tested for their effects upon germination and growth of several test species from the same area. Likewise, bioassays of simultaneous germination were carried out with some of the available seeds. 

Jenner, H.A. and Janssen-Mommen, J.P.M. (1989) Phytomonitoring of pulverized fuel ash leachates by the duckweed Lemna minor, in M. Munawar, G. Dixon, C.I. Mayfield, T. Reynoldson and M.H. Sadar (eds.), Environmental Bioassay Techniques and their Application Proceedings of the 1st International Conference held in Lancaster, England, 11-14 July 1988, Kluwer Academic Publishers, Dordrecht, Netherlands, pp. 361-366. 

McKnight, D.M., Feder, G.L. and Stiles, E A. (1981) Toxicity of volcanic-ash leachate to a blue-green alga. Results of a preliminary bioassay experiment, Environmental Science and Technology 15 (3),... 

As stated by Johnson (1993), "hazardous waste becomes a problem when it moves", Because water is the main vector for transporting pollutants from wastes towards receiving ecosystems, WASTOXHAS, presented hereinafter, is only focused on ecotoxicological assessment of different leachates with aquatic bioassays. 

Simulation leaching tests are upward-flow (NEN, 7343, 1995) and downward-flow column leaching tests (Huang et al., 2003). Laboratory leachates are collected on a regular basis, chemically monitored and tested with (at least) two aquatic bioassays (see below). 

The ecotoxicity of wastes has to be evaluated after application of bioassays to raw wastes and to their leachates (French Ministry of Environment, 1998). As emphasized several times in this book, bioassays give a direct and comprehensive estimate of environmental toxicity. When confronted with complex mixtures of chemicals, responses of biological tests integrate different factors such as antagonism, synergism, and bioavailability of pollutants. 

In undertaking our search of the literature linked to bioanalytical assessment of solid waste leachates (Tab. 2), we circumscribed it to small-scale toxicity testing performed on leachates. Furthermore, we did not exclude marine bioassays, but we exclusively selected literature references involving test battery approaches (TBAs) on solid wastes (or their elutriates). As defined previously in the first chapter of this book, a TBA represents a study conducted with two or more tests representing at least two biotic levels. As also pointed out in Section 2 of this chapter, TBAs are suitable to assess hazard at different levels so as not to underestimate ecotoxicity. Nevertheless, we have not excluded from this review publications describing other types of bioassays (e.g., terrestrial bioassays, sub-cellular bioassays or those carried out with recombinant DNA (micro)organisms and biosensors), when those were part of the TBA. 

Table 2. Application of bioassays to assess ecotoxicity of (solid) waste leachates test batteries are listed in chronological order.

Three bioassays a) 48h and 96h acute crustacean test (Daphnia pulex) b) 96h acute fish test (Oncorhynchus mykiss and Oncorhynchus nerka) c) residual oxygen fish test (Oncorhynchus mykiss and Oncorhynchus nerka) Municipal solid waste (MSW) leachates originating from a) Landfills b) Laboratory lysimeters (downward) c) Field lysimeters (downward) Unspecified pretreatment... 

Four bioassays a) 5 min acute bacterial test (Vibrio fischeri) b) 11 to 21 d algal test (Pseudokirchneriella subcapitata) c) 48h acute crustacean test (Daphnia magna) d) 96h acute fish test (Pimephales promelas) Municipal and industrial solid waste leachates originating from a sanitary landfill Filtered (glass fiber and 0.45 pm membrane filters for algal test) and unfiltered... 

Two bioassays a) 48h plate incorporation AMES test with Salmonella typhimurium his- (TA 98, 100, 1535, 1537 et 1538) b) 24h acute crustacean test (Daphnia magna) MSW landfill leachates Ashes and slags from MSW incinerator leachates Centrifuged and 0.45 pm filtered only for AMES test... 

Two bioassays a) 7d chronic shrimp test (Mysidopsis bahia) b) 7d chronic fish test (Menidia beryllina) Waste-to-energy (WTE) ash concrete leachates Sea-water leaching with stabilized wastes sea-water elutriation with crushed wastes decantation and/or filtration... 

Four bioassays a) 5, 15 and 30 min acute bacterial test (Vibrio MSW landfill leachates... 

Three bioassays a) 8d growth rate aquatic plant test (Lemna minor) b) 72h germination plant test (Lepidium sativum) and 8d root elongation plant test (Lepidium sativum) c) 72h germination plant test (Brassica rapa) and 8d root elongation plant test (Brassica rapa) Different industrial solid waste leachates Saline extraction... 

Three bioassays a) 48h acute rotifer test (Brachionus plicatilis) b) 120d chronic sea anemone test (Aiptasia pallida) c) Acute (48h) and chronic (19d) marine copepod test (Acartia tonsa) MSWI bottom and fly ash leachates Column and batch leaching tests with ocean water and acidic artificial rain... 

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