Use of nonlinear regression techniques for describing concentration‐response relationships of plant species exposed to contaminated site soils

Stephenson, Gerald R.; Koper, Nicola; Atkinson, G.; Solomon, Keith R.; Scroggins, Richard P.

doi:10.1002/etc.5620191218

Cited by 98 publications

(39 citation statements)

References 16 publications

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“…Regression analysis also allows for the calculation of effective concentration (EC x ) values and confidence intervals about those estimates. Nonlinear regression protocols have been developed for plants [48] and have been used successfully on microcosm‐derived plant data in conjunction with ANOVA [32,33], a recommended procedure for microcosm data [49]. However, calculation of power of an unreplicated regression design is not possible; hence, the risk of a Type II error is unknown [49].…”

Section: Discussionmentioning

confidence: 99%

Variation, replication, and power analysis ofMyriophyllumspp. microcosm toxicity data

Hanson¹,

Sanderson

Solomon

2003

Enviro Toxic and Chemistry

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Myriophyllum spp. have been proposed as a new standard laboratory aquatic macrophyte test species for the registration of pesticides. The main objectives of this investigation were to determine the power of Myriophyllum sibiricum and Myriophyllum spicatum toxicity data derived from an outdoor microcosm bioassay, to evaluate the variation of 10 different aquatic plant endpoints and to calculate the minimum detectable difference for these endpoints, to determine the replication required to detect ecologically significant changes from control for these endpoints, and to make recommendations for future field studies with Myriophyllum spp. Control data from four different studies that characterized haloacetic acid toxicity with Myriophyllum spp. for durations of three to six weeks during the summer of 1999 with five treatment levels (n = 3), including control, were examined. Endpoint coefficient of variation ranged, on average, from 6 to 28%. Node number and plant length endpoints were consistently the most statistically powerful for both plant species. It was possible to detect approximately 30% change from control in both endpoints with high statistical power (beta = 0.2, alpha = 0.05, n = 3). The range of minimum detectable differences was 40 to 60% for the other endpoints. Replication to detect a > or = 25% change from control would require an n of 2 to 21, depending on the endpoint. Myriophyllum sibiricum had slightly lower coefficients of variation and thus required fewer replicates than M. spicatum to be statistically significantly different from control values. Variation within microcosm studies was not significantly different from that of controlled laboratory studies, implying that most of the variation observed in the field is inherent in the plants. Based on statistical sensitivity, ecological relevance, and toxicological sensitivity, we recommend using plant length and root endpoints as indicators of toxicity under field conditions.

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Section: Discussionmentioning

confidence: 99%

Variation, replication, and power analysis ofMyriophyllumspp. microcosm toxicity data

Hanson¹,

Sanderson

Solomon

2003

Enviro Toxic and Chemistry

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“…Based on LC 50 values, ecotypes were considered different if their 95% confidence intervals (CI) did not overlap. Nonlinear regression can be legitimately used for estimating LC 50 values if the experimental design includes adequate coverage of the response range for treatments (i.e., different salinity levels) and having more than five treatments that include lethal and sublethal concentrations increases the likelihood of having an accurate regression [20,22]. In this study, we had six salinity levels which would provide a good response range for the regression; however, at 2.0 ppt, ecotypes had better visual quality and produced larger biomass than 0.2 ppt.…”

Section: Methodsmentioning

confidence: 99%

Ecotypes of Aquatic Plant Vallisneria americana Tolerate Different Salinity Concentrations

et al. 2020

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Increased salinity caused by saltwater intrusion or runoff from de-icing salts can severely affect freshwater vegetation and deteriorate aquatic ecosystems. These habitats can be restored with freshwater ecotypes (locally adapted populations) that tolerate above-normal salinity. Vallisneria americana is a prominent species in many freshwater ecosystems that responds differently to abiotic conditions such as substrate composition and fertility, so, in this study, we evaluated the effects of salt stress on 24 ecotypes of V. americana. Instant Ocean aquarium salt was used to create saline solutions (0.2 to 20.0 parts per thousand (ppt)), then plants were abruptly exposed to these solutions and maintained in these concentrations for five weeks before being visually assessed for quality and destructively harvested. Analysis of variance and nonlinear regression were used to calculate LC50 values—the lethal concentration of salt that reduced plant biomass and quality by 50% compared to control treatment. Growth rate and visual quality varied significantly among ecotypes, and ecotypes that were most and least sensitive to salt had 50% biomass reductions at 0.47 and 9.10 ppt, respectively. All ecotypes survived 10.0 ppt salinity concentration but none survived at 20.0 ppt, which suggests that the maximum salinity concentration tolerated by these ecotypes is between 15.0 and 20.0 ppt.

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“…After hormesis was evaluated, data were checked for normality, and the homoscedasticity of residuals from the dose‐response curves evaluated. The concentration of ammonium nitrate required to inhibit plant growth endpoints by 20% (IC20) was estimated for each soil by using reparameterized logarithmic dose‐response relationships [17,18].…”

Section: Methodsmentioning

confidence: 99%

Biogeochemical toxicity and phytotoxicity of nitrogenous compounds in a variety of arctic soils

Anaka

Wickstrom

Siciliano

2008

Enviro Toxic and Chemistry

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Ammonium nitrate (NH(4)NO(3)) is a common water pollutant associated with many industrial and municipal activities. One solution to reduce exposure of sensitive aquatic systems to nitrogenous compounds is to atomize (atmospherically disperse in fine particles) contaminated water over the Arctic tundra, which will reduce nitrogen loading to surface water. The toxicity of ammonium nitrate to Arctic soils, however, is poorly understood. In the present study, we characterized the biogeochemical toxicity and phytotoxicity of ammonium nitrate solutions in four different Arctic soils and in a temperate soil. Soil was exposed to a range of ammonium nitrate concentrations over a 90-d period. Dose responses of carbon mineralization, nitrification, and phytotoxicity endpoints were estimated. In addition to direct toxicity, the effect of ammonium nitrate on ecosystem resilience was investigated by dosing nitrogen-impacted soils with boric acid. Ammonium nitrate had no effect on carbon mineralization activity and only affected nitrification in one soil, a polar desert soil from Cornwallis Island, Northwest Territories, Canada. In contrast, ammonium nitrate applications (43 mmol N/L soil water) significantly impaired seedling emergence, root length, and shoot length of northern wheatgrass (Elymus lanceolatus). Concentrations of ammonium nitrate in soil water that inhibited plant parameters by 20% varied between 43 and 280 mmol N/L soil water, which corresponds to 2,100 to 15,801 mg/L of ammonium nitrate in the application water. Arctic soils were more resistant to ammonium nitrate toxicity compared with the temperate soil under these study conditions. It is not clear, however, if this represents a general trend for all polar soils, and because nitrogen is an essential macronutrient, nitrogenous toxicity likely should be considered as a special case for soil toxicity.

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Use of nonlinear regression techniques for describing concentration‐response relationships of plant species exposed to contaminated site soils

Cited by 98 publications

References 16 publications

Variation, replication, and power analysis ofMyriophyllumspp. microcosm toxicity data

Variation, replication, and power analysis ofMyriophyllumspp. microcosm toxicity data

Ecotypes of Aquatic Plant Vallisneria americana Tolerate Different Salinity Concentrations

Biogeochemical toxicity and phytotoxicity of nitrogenous compounds in a variety of arctic soils

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