Initial deposits and persistence of forest herbicide residues in sugar maple (Acersaccharum) foliage

1994 ◽  
Vol 24 (11) ◽  
pp. 2251-2262 ◽  
Author(s):  
Dean G. Thompson ◽  
D. G. Pitt ◽  
T. Buscarini ◽  
B. Staznik ◽  
D. R. Thomas ◽  
...  
Keyword(s):  
Sugar Maple ◽  
A Priori ◽  
Dry Mass ◽  
Application Rate ◽  
Parameter Estimates ◽  
Herbicide Residues ◽  
Similar Factor ◽  
Initial Deposition ◽  
Negative Exponential ◽  
Glyphosate Formulations

Initial deposition and subsequent fate of herbicide residues in sugar maple (Acersaccharum Marsh.) foliage were quantified following applications of three different formulations of glyphosate (VISION®, TOUCHDOWN®, MON14420) and one formulation of triclopyr ester (RELEASE®) in a comparative field study. Maximum initial residues were 529, 773, 777, and 1630 mg of acid equivalent per kilogram dry mass, respectively. Initial foliar residues were dependent upon application rate (r2 = 0.63 to 0.87) and increased by a similar factor (233 to 313 mg•kg−1) for each kilogram per hectare applied, irrespective of formulation type. Foliar residues dissipated following a negative exponential pattern with time, rates of which varied with initial concentration. Mean times to 50% dissipation were 2 days for all glyphosate formulations, 1.5 days for triclopyr ester, and 4 days for triclopyr acid. Mean times to 90% dissipation were <16 days for glyphosate formulations, 9 days for triclopyr ester, and 33 days for triclopyr acid. Multivariate analyses of intercept and rate parameter estimates indicated significant (p = 0.02) differences in dissipation patterns among treatments. Orthogonal contrasts confirmed a priori hypotheses that glyphosate residue dissipation was independent of the salt formulation applied, and that triclopyr ester dissipated faster than either glyphosate (p = 0.004) or triclopyr acid residues (p = 0.07). Results are considered in terms of the exposure and resultant potential toxicity to forest songbirds inhabiting or foraging in treated hardwood canopies.

Comparative fate of glyphosate and triclopyr herbicides in the forest floor and mineral soil of an Acadian forest regeneration site

2000 ◽  
Vol 30 (11) ◽  
pp. 1808-1816 ◽  
Author(s):  
Dean G Thompson ◽  
Douglas G Pitt ◽  
Teresa M Buscarini ◽  
Bozena Staznik ◽  
David R Thomas
Keyword(s):  
New Brunswick ◽  
Forest Floor ◽  
Forest Regeneration ◽  
Mineral Soil ◽  
Dry Mass ◽  
Litter Fall ◽  
Herbicide Residues ◽  
Residue Levels ◽  
Acadian Forest ◽  
Glyphosate Formulations

Following applications of three different salt formulations of glyphosate (Vision®, Touchdown®, and Mon14420) and an ester formulation of triclopyr (Release®) to an Acadian forest regeneration site in New Brunswick, Canada, the fate and persistence of herbicide residues in the forest floor and underlying mineral soil were investigated. Within 14 days of treatment, maximal residue levels (average 8.3 µg·g dry mass–1) were observed in the forest floor matrix following application of the glyphosate formulations, with higher values (45.7 µg·g dry mass–1) observed for triclopyr. Residue maxima in the underlying mineral soil were, on average, 5.7-fold lower than those in the forest floor. In both matrices, glyphosate residues declined exponentially with time, irrespective of the formulation applied. Among the glyphosate treatments no significant differences (p = 0.16, p = 0.97, for forest floor and mineral soil respectively) were observed in the estimated times to 50% dissipation (DT50). Overall, average DT50 values for glyphosate were estimated as 12 ± 2 and 10 ± 3 days for the forest floor matrix and mineral soil, respectively. Triclopyr residues, particularly in the forest floor, were characterized by a series of transient increases, possibly reflecting temporally varying inputs from dew, rainwash, or litter fall from surrounding treated vegetation. Triclopyr residues also dissipated with time, with approximate DT50 values ranging from 39 to 69 days in the forest floor and mineral soil, respectively.

Generalised DOPs with Consideration of the Influence Function of Signal-in-Space Errors

2011 ◽  
Vol 64 (S1) ◽  
pp. S3-S18 ◽  
Author(s):  
Yuanxi Yang ◽  
Jinlong Li ◽  
Junyi Xu ◽  
Jing Tang
Keyword(s):  
Least Squares ◽  
Stochastic Models ◽  
Influence Function ◽  
A Priori ◽  
Functional Model ◽  
Global Navigation Satellite Systems ◽  
Parameter Estimates ◽  
Model Parameters ◽  
Integrated Navigation ◽  
Satellite Systems

Integrated navigation using multiple Global Navigation Satellite Systems (GNSS) is beneficial to increase the number of observable satellites, alleviate the effects of systematic errors and improve the accuracy of positioning, navigation and timing (PNT). When multiple constellations and multiple frequency measurements are employed, the functional and stochastic models as well as the estimation principle for PNT may be different. Therefore, the commonly used definition of “dilution of precision (DOP)” based on the least squares (LS) estimation and unified functional and stochastic models will be not applicable anymore. In this paper, three types of generalised DOPs are defined. The first type of generalised DOP is based on the error influence function (IF) of pseudo-ranges that reflects the geometry strength of the measurements, error magnitude and the estimation risk criteria. When the least squares estimation is used, the first type of generalised DOP is identical to the one commonly used. In order to define the first type of generalised DOP, an IF of signal–in-space (SIS) errors on the parameter estimates of PNT is derived. The second type of generalised DOP is defined based on the functional model with additional systematic parameters induced by the compatibility and interoperability problems among different GNSS systems. The third type of generalised DOP is defined based on Bayesian estimation in which the a priori information of the model parameters is taken into account. This is suitable for evaluating the precision of kinematic positioning or navigation. Different types of generalised DOPs are suitable for different PNT scenarios and an example for the calculation of these DOPs for multi-GNSS systems including GPS, GLONASS, Compass and Galileo is given. New observation equations of Compass and GLONASS that may contain additional parameters for interoperability are specifically investigated. It shows that if the interoperability of multi-GNSS is not fulfilled, the increased number of satellites will not significantly reduce the generalised DOP value. Furthermore, the outlying measurements will not change the original DOP, but will change the first type of generalised DOP which includes a robust error IF. A priori information of the model parameters will also reduce the DOP.

scholarly journals Impacts of three glyphosate formulations on gonadal development of Xenopus laevis

2021 ◽  
Vol 5 ◽  
pp. 239784732110314
Author(s):  
Oluwaseun O Babalola ◽  
J Christoff Truter ◽  
Johannes H van Wyk
Keyword(s):  
Xenopus Laevis ◽  
Body Mass ◽  
Reproductive System ◽  
Sex Ratios ◽  
Gonadal Development ◽  
Application Rate ◽  
Amphibian Declines ◽  
The Body ◽  
Pesticide Pollution ◽  
Glyphosate Formulations

The emergence of widespread morphological malformations in the reproductive system of wildlife is generating increasing concerns. This concern is because the observed malformities may be linked to pollution by pesticides and other chemicals. The amphibian declines, for example, have been linked to pesticide pollution among other factors. Using an extended Xenopus Metamorphosis Assay protocol, until the tadpoles metamorphosized, the exposure impacts of three glyphosate formulations, namely, Roundup, Kilo Max and Enviro Glyphosate, were assessed on the reproductive system of Xenopus laevis, vis-a-vis the body mass, sex ratios and morphological malformations as endpoints. The exposure concentrations ranged between 0.2–0.6 mg/L, 0.9–28 mg/L and 90–280 mg/L for Roundup, Enviro Glyphosate, and Kilo Max, respectively. Both Kilo Max and Enviro Glyphosate formulations significantly reduced the body mass of the metamorphs compared to the control. In sex ratios, only Kilo Max altered the percentage sex ratio of the treated frogs at a ratio of 68:32 (F:M) compared to 50:50 ratio in the control. In reproductive malformations, the three formulations showed abnormality index range of 22.3–49%, 17.5–37.5% and 20–30% for the Kilo Max, Enviro Glyphosate and Roundup formulations, respectively, compared to 7.5% in the control. Observed reproductive malformations include mixed sex, translucence, aplasia, segmented hypertrophy and segmented aplasia and translucence. This result indicates that some of the glyphosate formulations have the capacity to cause widespread reproductive malformations in a way that could reduce the reproductive fitness of the amphibian. Care must therefore be taken to reduce the application rate of these formulations, particularly in aquatic environments.

scholarly journals Areal parameter estimates from multiple datasets

2019 ◽  
Vol 475 (2231) ◽  
pp. 20190352 ◽  
Author(s):  
B. L. N. Kennett
Keyword(s):  
Significant Contribution ◽  
A Priori ◽  
Relative Weight ◽  
Parameter Estimates ◽  
Multiple Datasets ◽  
Wide Range ◽  
Spatially Distributed ◽  
Data Points ◽  
Spatial Terms ◽  
Weighted Combination

A wide range of methods exist for interpolation between spatially distributed points drawn from a single population. Yet often multiple datasets are available with differing distribution, character and reliability. A simple scheme is introduced to allow the fusion of multiple datasets. Each dataset is assigned an a priori spatial influence zone around each point and a relative weight based on its physical character. The composite result at a specific location is a weighted combination of the spatial terms for all the available data points that make a significant contribution. The combination of multiple datasets is illustrated with the construction of a unified Moho surface in part of southern Australia from results exploiting a variety of different styles of analysis.

Comparison of static and dynamic closed chambers for measurement of soil respiration under field conditions

1992 ◽  
Vol 72 (4) ◽  
pp. 605-609 ◽  
Author(s):  
P. Rochette ◽  
E. G. Gregorich ◽  
R. L. Desjardins
Keyword(s):  
Soil Respiration ◽  
Sandy Loam ◽  
Flux Measurement ◽  
Organic Soil ◽  
Exponential Model ◽  
Field Conditions ◽  
Parameter Estimates ◽  
Static Chamber ◽  
The Difference ◽  
Negative Exponential

The objective of this study was to compare the dynamic closed and static chamber techniques for the measurement of soil respiration under field conditions. The static chamber method consistently produced lower soil respiration values than did the dynamic closed system and the difference was larger at higher CO2 fluxes. A negative exponential model describes the relation between CO2 fluxes measured by both techniques. A good fit was obtained for measurements on a sandy loam soil (R2 = 0.61) and an organic soil (R2 = 0.74) but parameter estimates were different for each soil. Key words: Carbon dioxide, enclosure, gas flux measurement

Spatial Flows and Spatial Patterns

1984 ◽  
Vol 16 (4) ◽  
pp. 529-543 ◽  
Author(s):  
A S Fotheringham
Keyword(s):  
Spatial Structure ◽  
Spatial Patterns ◽  
Spatial Interaction ◽  
A Priori ◽  
Parameter Estimates ◽  
Spatial Interaction Models ◽  
Significant Bias ◽  
Spatial System ◽  
Decay Parameters ◽  
Spatial Flows

The misspecification of gravity spatial interaction models has recently been described by the author. The bias in parameter estimates that results from such misspecification appears to produce the ‘map pattern effect’ or ‘spatial structure bias’ in estimated distance-decay parameters. A further aspect of the misspecification bias in gravity parameter estimates is explored here. The severity of the bias is shown to vary in a predictable manner with variations in spatial structure. In particular, the bias is shown to be dependent upon the pattern of accessibility that exists within a spatial system. The relevant aspects of this pattern are discussed for intraurban and interurban (or interregional) flow matrices. It is shown that from an examination of the spatial structure of centres in a spatial system it is possible, a priori, to identify whether significant bias will arise in the calibration of a gravity model. Certain configurations of centres are shown theoretically to produce maximal bias. The author thus answers the question, “why do gravity parameter estimates appear to be biased in some systems but not in others?”

scholarly journals Fertilizing Containerized Atlantic White Cedar Seedlings

2005 ◽  
Vol 23 (2) ◽  
pp. 97-100
Author(s):  
Scott A. Derby ◽  
L. Eric Hinesley
Keyword(s):  
Dry Mass ◽  
Application Rate ◽  
Nutrient Concentrations ◽  
First Year ◽  
White Cedar ◽  
Chamaecyparis Thyoides ◽  
Atlantic White Cedar ◽  
P Content ◽  
Foliar Nutrient ◽  
Foliar Nutrient Concentrations

Abstract Containerized Atlantic white cedar [Chamaecyparis thyoides (L.) B.S.P.] seedlings were fertilized with five rates (0.0, 2.4, 4.8, 7.2, and 9.6 kg/m3) (0, 4, 8, 12, and 16 lb/yd3) of controlled-release fertilizers (CRF) [Osmocote 15N–4.0P–10.0K (15N–9P2O5–12K2O), 12–14 month southern formulation, with micros; and Polyon 18N–2.6P–10.0K (18N–6P2O5–12K2O), 9-month formulation, with micros]. Height, stem diameter, dry mass, and foliar nutrient concentrations were evaluated after 16 weeks. Growth was affected by fertilizer source and application rate, with no interaction. In general, the response to increasing fertilization was quadratic. Osmocote yielded larger plants than Polyon, probably owing to its higher P content. Osmocote (4.8 to 7.2 kg/m3) (8 to 12 lb/yd3) or Polyon (7.2 kg/m3) (12 lb/yd3) is suggested for container-grown seedlings the first year.

scholarly journals Nutrient Uptake in Poinsettia during Different Stages of Physiological Development

1997 ◽  
Vol 122 (4) ◽  
pp. 565-573 ◽  
Author(s):  
Brian E. Whipker ◽  
P. Allen Hammer
Keyword(s):  
Nutrient Uptake ◽  
Nutrient Concentration ◽  
Nutrient Content ◽  
Dry Mass ◽  
Application Rate ◽  
Plant Nutrient ◽  
Fertilizer Rate ◽  
Fertilization Rates ◽  
Total Plant ◽  
Plant Nutrient Content

`Supjibi' poinsettias (Euphorbia pulcherrima Willd.) were grown hydroponically for 15 weeks in nutrient solutions with 100-15-100, 200-30-200, or 300-46-300 (in mg·L-1 of N-P-K) to determine nutrient uptake patterns and accumulation rates. Results indicate that increasing fertilization rates from 100 to 300 mg·L-1 of N and K did not significantly influence the plant dry mass or the nutrient concentration of P, K, Ca, Mg, Na, B, Cu, Fe, Mn, Mo, and Zn in poinsettias. NH4-N concentration in the leaves, stems, and roots were lowest with the 100-mg·L-1 N fertilization rate and increased as the N application rate increased to 200 and 300 mg·L-1. Leaf P concentration levels from 1 week after potting through anthesis were above 1.3%, which exceeds the recommended level of 0.9%. When the plant tissue dry mass for each fertilizer rate was transformed by the natural log and multiplied by the mean tissue nutrient concentration of each fertilizer rate, there were no significant differences among the three fertilization rates when the total plant nutrient content was modeled for N, P, or K. Increasing the fertilizer application rate above 100 mg·L-1 N and K and 15 mg·L-1 P decreased total plant content of Ca, Mg, Mn, and Zn and increased the total plant Fe content. The results of the weekly nutrient uptake based on the total plant nutrient content in this study suggests that weekly fertilization rates should increase over time from potting until anthesis. Rates (in mg) that increase from 23 to 57 for N (with 33% of the total N supplied in the NH4-N form), 9 to 18.5 for P, 19 to 57 for K, 6 to 15 for Ca, and 3 to 8 for Mg can be applied without leaching to poinsettias and produce adequate growth in the northern United States.

scholarly journals Mulched Maple and Oak Leaves Associated with a Reduction in Common Dandelion Populations in Established Kentucky Bluegrass

2009 ◽  
Vol 19 (2) ◽  
pp. 297-304 ◽  
Author(s):  
Alexander R. Kowalewski ◽  
Douglas D. Buhler ◽  
N. Suzanne Lang ◽  
Muraleedharan G. Nair ◽  
John N. Rogers
Keyword(s):  
Particle Size ◽  
Leaf Litter ◽  
Sugar Maple ◽  
Poa Pratensis ◽  
Acer Rubrum ◽  
Kentucky Bluegrass ◽  
Application Rate ◽  
Effective Control ◽  
Common Dandelion ◽  
Leaf Species

Previous research has shown that maple (Acer spp.) leaf litter resulted in fewer common dandelions (Taraxacum officinale) when mulched into established turfgrass. However, the leaves used in that research may have contained herbicide residues and were separated by genus, not species. Our research compared the effects of pesticide-free mulched maple and oak (Quercus spp.) leaves on dandelion populations in an established kentucky bluegrass (Poa pratensis) stand maintained as a residential lawn on sandy loam soil. The objectives of this study were to quantify the effectiveness of maple or oak leaf mulches as an organic common dandelion control method and to identify which maple species and rates (particle size and rate per unit area) provided the most effective control. The experimental design was a randomized complete block with treatments arranged as a 5 × 2 × 2 + 1 factorial, with tree leaf species, leaf particle size, leaf application rate, and control as main factors. Leaf species were red maple (Acer rubrum), silver maple (A. saccharinum), sugar maple (A. saccharum), high sugar content sugar maple, and red oak (Quercus rubra). Particle sizes were coarse (0.4–1.0 inch2) and fine (≤0.2 inch2), and application rates were low (0.5 kg·m−2) and high (1.5 kg·m−2). Mulch applications were made in Fall 2003 and 2004 and data were collected beginning in Spring 2004 on kentucky bluegrass spring green-up, and common dandelion plant counts. The high application rate, regardless of tree genus or species, resulted in the highest green-up ratings. Common dandelion plant counts after one (2003) and two (2003 and 2004) mulch applications at the high rate showed that up to 80% and 53% reduction was achieved, respectively. Results indicate that mulching leaves regardless of genus (oak or maple) or maple species into established turfgrass as a leaf litter disposal method will increase spring green-up and contribute to a reduction in common dandelion population.

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