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>_soil‑air) 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>_soil‑air 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>_soil‑air values of 22 semivolatile current- and historic-use pesticides and their degradation products. <i>K</i>_soil‑air 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>_soil‑air measurements were made. Measured values were used to derive a predictive equation for pesticide <i>K</i>_soil‑air 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>_soil‑air predictive equation and a previously described pesticide volatilization model, were compared to previous results and showed that the choice of <i>K</i>_soil‑air 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