4 research outputs found
Correction to An Improved Screening Tool for Predicting Volatilization of Pesticides Applied to Soils
Correction
to An Improved Screening Tool for Predicting
Volatilization of Pesticides Applied to Soil
Influence of Temperature, Relative Humidity, and Soil Properties on the Soil–Air Partitioning of Semivolatile Pesticides: Laboratory Measurements and Predictive Models
Soil–air partition
coefficient (<i>K</i><sub>soil‑air</sub>) values
are often employed to investigate the fate of organic contaminants
in soils; however, these values have not been measured for many compounds
of interest, including semivolatile current-use pesticides. Moreover,
predictive equations for estimating <i>K</i><sub>soil‑air</sub> values for pesticides (other than the organochlorine pesticides)
have not been robustly developed, due to a lack of measured data.
In this work, a solid-phase fugacity meter was used to measure the <i>K</i><sub>soil‑air</sub> values of 22 semivolatile current-
and historic-use pesticides and their degradation products. <i>K</i><sub>soil‑air</sub> values were determined for two
soils (semiarid and volcanic) under a range of environmentally relevant
temperature (10–30 °C) and relative humidity (30–100%)
conditions, such that 943 <i>K</i><sub>soil‑air</sub> measurements were made. Measured values were used to derive a predictive
equation for pesticide <i>K</i><sub>soil‑air</sub> values based on temperature, relative humidity, soil organic carbon
content, and pesticide-specific octanol–air partition coefficients.
Pesticide volatilization losses from soil, calculated with the newly
derived <i>K</i><sub>soil‑air</sub> predictive equation
and a previously described pesticide volatilization model, were compared
to previous results and showed that the choice of <i>K</i><sub>soil‑air</sub> predictive equation mainly affected the
more-volatile pesticides and that the way in which relative humidity
was accounted for was the most critical difference
Understanding and Predicting the Fate of Semivolatile Organic Pesticides in a Glacier-Fed Lake Using a Multimedia Chemical Fate Model
Melting
glaciers release previously ice-entrapped chemicals to
the surrounding environment. As glacier melting accelerates under
future climate warming, chemical release may also increase. This study
investigated the behavior of semivolatile pesticides over the course
of one year and predicted their behavior under two future climate
change scenarios. Pesticides were quantified in air, lake water, glacial
meltwater, and streamwater in the catchment of Lake Brewster, an alpine
glacier-fed lake located in the Southern Alps of New Zealand. Two
historic-use pesticides (endosulfan I and hexachlorobenzene) and three
current-use pesticides (dacthal, triallate, and chlorpyrifos) were
frequently found in both air and water samples from the catchment.
Regression analysis indicated that the pesticide concentrations in
glacial meltwater and lake water were strongly correlated. A multimedia
environmental fate model was developed for these five chemicals in
Brewster Lake. Modeling results indicated that seasonal lake ice cover
melt, and varying contributions of input from glacial melt and streamwater,
created pulses in pesticide concentrations in lake water. Under future
climate scenarios, the concentration pulse was altered and glacial
melt made a greater contribution (as mass flux) to pesticide input
in the lake water
Increased Concentrations of Polycyclic Aromatic Hydrocarbons in Alpine Streams during Annual Snowmelt: Investigating Effects of Sampling Method, Site Characteristics, and Meteorology
Silicone
passive samplers and macroinvertebrates were used to measure
time-integrated concentrations of polycyclic aromatic hydrocarbons
(PAHs) in alpine streams during annual snowmelt. The three sampling
sites were located near a main highway in Arthur’s Pass National
Park in the Southern Alps of New Zealand. A similar set of PAH congeners,
composed of 2–4 rings, were found in silicone passive samplers
and macroinvertebrates. The background PAH concentrations were similar
at all sites, implying that proximity to the highway did not affect
concentrations. In passive samplers, an increase of PAH concentrations
by up to seven times was observed during snowmelt. In macroinvertebrates,
the concentration changes were moderate; however, macroinvertebrate
sampling did not occur during the main pulse observed in the passive
samplers. The extent of vegetation in the catchment appeared to affect
the concentration patterns seen at the different stream sites. A strong
correlation was found between PAH concentrations in passive samplers
and the amount of rainfall in the study area, indicating that the
washout of contaminants from snowpack by rainfall was an important
process