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1.
Environ Sci Technol ; 2021 Mar 29.
Artigo em Inglês | MEDLINE | ID: mdl-33779156

RESUMO

Pesticide dissipation from plant surfaces depends on a variety of factors including meteorological conditions, the pesticide's physicochemical properties, and plant characteristics. Models already exist for describing pesticide behavior in agriculture fields; however, they do not account for pesticide-specific, condition-specific foliar photodegradation and the importance of this component in such models has not yet been investigated. We describe here the Pesticide Dissipation from Agricultural Land (PeDAL) model, which combines (a) multiphase partitioning to predict volatilization, (b) a new kinetics module for predicting photodegradation on leaf surfaces under varying light conditions based on location and timing, and (c) a generic foliar penetration component. The PeDAL model was evaluated by comparing measured pesticide dissipation rates from field experiments, described as the time for the pesticide concentration on leaves to decrease by half (DT50), to ones generated by the model when using the reported field conditions. A sensitivity analysis of the newly developed foliar photodegradation component was conducted. We also showed how the PeDAL could be used by applicators and regulatory agencies. First, we used the model to examine how pesticide application timing affects dissipation rates. Second, we demonstrated how the model can be used to produce emission flux values for use in atmospheric dispersion and transport models.

2.
Sci Total Environ ; 773: 145146, 2021 Jun 15.
Artigo em Inglês | MEDLINE | ID: mdl-33582324

RESUMO

Local differences in trophic structure and composition of organic matter subsidies can influence the capacity of soft sediment communities to assimilate recycled organic matter from processes such as salmon farm enrichment. The present study combines biochemical analysis with biomass density information on soft sediment taxa collected within the depositional footprint of salmon farms and at reference sites in the Marlborough Sounds, New Zealand. Distinct biochemical signatures confirmed that the flux of organic matter from salmon farms was an important subsidy for soft sediment communities. Isotopic modelling demonstrated that the proportion of biomass supported by farm-derived organic matter did not change in a consistent pattern along the 300 m gradient from each farm site, whereas the average trophic level of communities decreased with increasing proximity to farms. High variability in both the total biomass and the distribution of biomass across trophic levels occurred among sites downstream of farms and among individual farms. Consequently, estimates of basal organic matter assimilation per unit area by communities differed by several orders of magnitude among sites. Total organic matter assimilation tended to decrease with increasing proximity to farms due to a shift towards a more detrital based community. Differences in basal organic matter assimilation among farms did not appear to be directly related to local flow regime, but instead was closely linked to differences in the soft sediment community composition likely influenced by an array of anthropogenic and environmental factors. The results presented here highlight the importance of considering local variability in basal organic matter source pools, and the potential for synergistic and cumulative effects to drive changes in food web trophodynamics when assessing the impacts of aquaculture on soft sediment communities.


Assuntos
Sedimentos Geológicos , Salmão , Animais , Aquicultura , Nova Zelândia , Alimentos Marinhos
3.
Sci Total Environ ; 754: 141941, 2021 Feb 01.
Artigo em Inglês | MEDLINE | ID: mdl-33254881

RESUMO

The global intensification of agriculture has resulted in pesticides playing an increasingly important role as anthropogenic stressors and drivers of environmental change. There is also a growing need to determine if other environmental stressors, especially those predicted to worsen with climate change, interact with pesticides to alter their effects on non-target biota. Two such stressors are increased extreme temperature events and periods of food limitation. This study is the first to investigate the combined effects of the world's most widely used insecticide, imidacloprid, with heatwaves and food limitation on a freshwater animal. A 6-week, full-factorial laboratory experiment with Deleatidium spp. mayfly nymphs was performed to investigate the potential for direct and delayed interactive effects of simulated heatwaves and starvation with chronic exposure to a field-realistic concentration of imidacloprid (0.4 µg/L). The experiment included two 6-day simulated heatwaves, one during a starvation period prior to imidacloprid addition, and one during the first 6 days of imidacloprid exposure. The simulated heatwaves alone caused such drastic negative effects on Deleatidium survival and mobility that mainly antagonistic interactions were observed with the other stressors, though delayed synergisms between imidacloprid and the second heatwave also affected mayfly mobility. Time-cumulative toxicity of imidacloprid was evident, with imidacloprid first affecting mayfly mobility after 12 days but eventually causing the strongest effects of all manipulated stressors. However, lethal effects of imidacloprid could only be detected in the absence of heatwaves and starvation, possibly as a result of selection for stronger individuals due to prior exposure to these stressors. Our findings demonstrate that heatwaves of increasing severity will critically affect sensitive freshwater organisms such as mayflies, and that the impacts of widespread pesticide use on freshwater ecosystems under global climate change cannot be ignored.


Assuntos
Ephemeroptera , Inseticidas , Poluentes Químicos da Água , Animais , Ecossistema , Humanos , Inseticidas/toxicidade , Neonicotinoides/toxicidade , Nitrocompostos/toxicidade , Rios , Poluentes Químicos da Água/toxicidade
4.
Sci Total Environ ; : 143263, 2020 Nov 12.
Artigo em Inglês | MEDLINE | ID: mdl-33246716

RESUMO

Contamination of the environment with toxic chemicals such as pesticides has become a global problem. Understanding the role of chemical contaminants as stressors in ecological systems is therefore an important research need in the 21st century. In surface freshwaters, mixtures of neonicotinoid insecticides are being detected around the world as more monitoring data become available. Combinations of imidacloprid, clothianidin and thiamethoxam are commonly found, but studies testing their combined toxicities to freshwater invertebrates are rare. Taking a multiple-stressor approach, we employed a full-factorial design to investigate the individual and combined chronic toxicities of these three neonicotinoids in a 28-day laboratory experiment using Deleatidium spp. mayfly nymphs. Imidacloprid (1.2 µg/L achieved concentration) reduced mayfly survival (by 50% on Day 28) and mobility (~100%) more than clothianidin (1.1 µg/L, affecting about 25% of individuals across the responses measured) and thiamethoxam (2.9 µg/L, affecting 12%). Imidacloprid interacted with the other two neonicotinoids to cause a greater-than-additive negative effect when combined until 25 days of exposure, after which the strong negative overall effects of imidacloprid prevented these interactions from being observed. Our findings represent a novel contribution to multiple-stressor research by demonstrating the combined effects of chronic exposure to environmentally relevant neonicotinoid concentrations on an ecologically important stream insect taxon. These results emphasise the higher toxicity of imidacloprid to non-target freshwater insects compared to clothianidin and thiamethoxam, implying that stricter regulation to control the use of imidacloprid may need to be prioritised to protect vulnerable aquatic insect populations that provide key links to terrestrial food webs. Finally, our study provides an ecological, multiple-stressor comparison for related ecotoxicological investigations indicating neonicotinoid mixtures can deviate from additive toxicity.

5.
J Hazard Mater ; : 124117, 2020 Sep 30.
Artigo em Inglês | MEDLINE | ID: mdl-33129601

RESUMO

Short-chain chlorinated paraffins (SCCPs) and medium-chain chlorinated paraffins (MCCPs) were measured in tree bark samples. These samples were collected around a chemical industrial park containing several chlorinated paraffin (CP) production plants, in a nearby city (Zhengzhou), and along a transect between the industrial park and city. Theoretical air concentrations were back-calculated from concentrations in bark using a predictive equation for estimating equilibrium bark-air partition coefficients. We developed this equation from a series of previously published Kbark-air measurements. Comparison of the normalized concentration profiles along south to north transects showed that wind played only a minor role in CP concentrations and profiles in the region. Three distinct source profiles were found in the complex source region. A fingerprint analysis technique was used to quantify the contribution of each source to the CP burden at various locations along the transect. We found that CP profiles at sites up to 6 km from the industrial park were strongly influenced by CP plant emissions, whereas the sites located in the rural zone and rural-urban interface were influenced by a mixture of CP plant emissions and the neighboring city.

6.
J Chromatogr A ; 1627: 461414, 2020 Sep 13.
Artigo em Inglês | MEDLINE | ID: mdl-32823112

RESUMO

Various techniques have been evaluated for the extraction and cleanup of pesticides from environmental samples. In this work, a Selective Pressurized Liquid Extraction (SPLE) method for pesticides was developed using a Thermo Fisher Scientific Accelerated Solvent Extraction (ASE) system. This instrument was compared to the newly introduced (2017) extraction instrument, the Energized Dispersive Guided Extraction (EDGE) system, which combines Pressurized Liquid Extraction (PLE) and dispersive Solid Phase Extraction (dSPE). We first optimized the SPLE method using the ASE instrument for pesticide extraction from alfalfa leaves using layers of Florisil and graphitized carbon black (GCB) downstream of the leaf homogenate in the extraction cell (Layered ASE method). We then compared results obtained for alfalfa and citrus leaves with the Layered ASE method to those from a method in which the leaf homogenate and sorbents were mixed (Mixed ASE method) and to similar methods modified for use with EDGE (Layered EDGE and Mixed EDGE methods). The ASE and EDGE methods led to clear, colorless extracts with low residual lipid weight. No significant differences in residual lipid masses were observed between the methods. The UV-Vis spectra showed that Florisil removed a significant quantity of the light-absorbing chemicals, but that GCB was required to produce colorless extracts. Recoveries of spiked analytes into leaf homogenates were generally similar among methods, but in several cases, significantly higher recoveries were observed in ASE extracts. Nonetheless, no significant differences were observed among pesticide concentrations in field samples when calculated with the isotope dilution method in which labelled surrogates were added to samples before extraction. The extraction time with the ASE methods was ~45 minutes, which was ~4.5 times longer than with the EDGE methods. The EDGE methods used ~10 mL more solvent than the ASE methods. Based on these results, the EDGE is an acceptable extraction instrument and, for most compounds, the EDGE had a similar extraction efficiency to the ASE methods.


Assuntos
Técnicas de Química Analítica/métodos , Praguicidas/análise , Folhas de Planta/química , Solventes/química , Lipídeos/química , Medicago sativa/química , Resíduos de Praguicidas/análise , Extratos Vegetais/química , Espectrofotometria Ultravioleta
7.
Environ Sci Technol ; 54(12): 7302-7308, 2020 06 16.
Artigo em Inglês | MEDLINE | ID: mdl-32436696

RESUMO

A solid-phase fugacity meter was used to measure the soil-air partition coefficients of three semivolatile pesticides (chlorpyrifos, pyrimethanil, and trifluralin) in the absence of additional adjuvants (Ksoil-air,AI), as part of commercial formulations (Ksoil-air,formulation), and as formulation mixtures with an additional spray adjuvant added (Ksoil-air,formulation+spray adjuvant). Chlorpyrifos Ksoil-air,formulation values were also measured over 15-30 °C, allowing for the change in internal energy of the phase transfer reaction (Δsoil-airU) to be calculated and compared to the Δsoil-airU for Ksoil-air,AI from the literature. Measured Ksoil-air values were then used as input parameters in a pesticide volatilization model to understand how their variability affects pesticide volatilization rates under different conditions. Initial experiments conducted at ∼24 °C indicated that all pesticides volatilized more readily in the presence of adjuvants than in their absence and that the additional spray adjuvant had minimal impact. The Δsoil-airU values were 328 and 90 kJ/mol for chlorpyrifos in the absence and presence of formulation adjuvants, respectively, suggesting that adjuvants may weaken or disrupt intermolecular attractions between pesticide molecules and soil. At temperatures below 24.5 °C, modeled chlorpyrifos volatilization rates were higher in the presence of adjuvants than in their absence; however, the opposite occurred at temperatures above 24.5 °C.


Assuntos
Clorpirifos , Praguicidas , Poluentes do Solo , Praguicidas/análise , Solo , Poluentes do Solo/análise , Volatilização
8.
Chemosphere ; 243: 125194, 2020 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-31739250

RESUMO

A field study was conducted to further our understanding about the fate and transport of the organophosphate insecticide, chlorpyrifos, and its degradation product, chlorpyrifos oxon. Leaf, soil and air sampling was conducted for 21 days after chlorpyrifos application to a field of purple tansy (Phacelia tanacetifolia). Air samples were collected using a high-volume air sampler (HVAS) and seven battery-operated medium-volume active air samplers placed around the field and on a 500-m transect extending away from the field. Chlorpyrifos was detected every day of the sampling period in all matrices, with concentrations decreasing rapidly after application. Chlorpyrifos oxon was only detected in air samples collected with the HVAS during the first three days after application. Wind direction played a significant role in controlling the measured air concentrations in near-field samples. The SCREEN3 model and chlorpyrifos' Characteristic Travel Distance (CTD) were used to predict modelled chlorpyrifos concentrations in air along the transect. The concentration trend predicted by the SCREEN3 model was similar to that of measured concentrations whereas CTD-modelled concentrations decreased at a significantly slower rate, indicating that downwind chlorpyrifos concentrations in air were primarily controlled by air dispersion. The SCREEN3-predicted chlorpyrifos concentrations were >5 times higher than measured concentrations, indicating that simple approaches for calculating accurate pesticide volatilization fluxes from agricultural fields are still needed. Finally, we found that measured concentrations in air on Days 0-2 at locations up to 500 m from the field were at levels considered concerning for human health.


Assuntos
Clorpirifos/análise , Inseticidas/análise , Clorpirifos/análogos & derivados , Monitoramento Ambiental , Humanos , Modelos Químicos , Praguicidas/análise , Folhas de Planta/química , Solo , Volatilização , Vento
9.
Environ Sci Technol ; 54(4): 2202-2209, 2020 02 18.
Artigo em Inglês | MEDLINE | ID: mdl-31858785

RESUMO

The Pesticide Loss via Volatilization model was developed to predict and understand pesticide volatilization rates from a planted agricultural field. The model allows the user to adjust the properties of the pesticide, various soil and plant descriptors, and climatic conditions. A useful output from the model is the 24 h cumulative percentage volatilization (CPV24h) loss. The model was validated by comparing modeled CPV24h values to measured ones compiled from the literature. Sensitivity analysis showed that the plant intercept fraction (%I), leaf area index (LAI), and leaf height (hleaf) strongly affect volatilization rates of plant- and soil-sorbed pesticides whereas LAI, hleaf, and the percent of water on the plant surface strongly affect more water-soluble pesticides. The model showed that most pesticides volatilize more readily from plants than from soil and that volatilization rates vary significantly for certain pesticides (but not all) when applied to plants at different growth stages and for different species of plants. Results are displayed on chemical space diagrams to paint a clear picture of how CPV24h varies for chemicals with different properties under different conditions.


Assuntos
Praguicidas , Poluentes do Solo , Plantas , Solo , Volatilização
10.
Sci Total Environ ; 698: 134264, 2020 Jan 01.
Artigo em Inglês | MEDLINE | ID: mdl-31494416

RESUMO

Phthalate esters (PAEs) have been shown to be ubiquitous in abiotic and biotic environmental compartments; however, information about bioaccumulation behavior and human exposure, both via environmental exposure and the diet, are limited. Herein, we report the concentrations and composition profiles of phthalate esters (PAEs) in biological samples, river water, indoor air, and outdoor air samples collected from an agricultural site in western China. Dibutyl phthalate (DNBP) occupied a relatively high abundance in biological samples, discrepant with the environmental samples in which di-(2-ethylhexyl) phthalate (DEHP) was the dominant congener. Significant correlations (P < 0.05) were observed between the biota and river water samples, indicating that river water heavily influenced PAE accumulation in biological samples. The mean log Bioaccumulation Factors (BAFs) varied from 0.91 to 2.96, which implies that most PAE congeners are not likely to accumulate in organisms. No obvious trends were observed between log octanol-water partition coefficient (KOW) and log BAF values, nor between log octanol-air partition coefficient (KOW) and biota-air accumulation factors (BAAFs). Nevertheless, the calculated log air-water partitioning factors (AWPFs) of diethyl phthalate (DEP), dimethyl phthalate (DMP), and butyl benzyl phthalate (BBP) were similar to predicted values whereas those for diisobutyl phthalate (DIBP), DNBP and DEHP were significantly higher. The estimated daily intakes of PAEs via food ingestion and environmental exposure were 15, 9.4 and 1.2 ng/kg-bw/day in toddlers, children and adults, respectively, laying at the low end of the reported data and well below the reference dose.


Assuntos
Exposição Ambiental/estatística & dados numéricos , Poluentes Ambientais/análise , Ésteres/análise , Ácidos Ftálicos/análise , China , Dibutilftalato/análogos & derivados , Dibutilftalato/análise , Humanos
11.
Environ Pollut ; 254(Pt A): 112973, 2019 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-31401523

RESUMO

New Zealand uses more than a ton of pesticides each year; many of these are mobile, relatively persistent, and can make their way into waterways. While considerable effort goes into monitoring nutrients in agricultural streams and programs exist to monitor pesticides in groundwater, very little is known about pesticide detection frequencies, concentrations, or their potential impacts in New Zealand streams. We used the 'Polar Organic Chemical Integrative Sampler' (POCIS) approach and grab water sampling to survey pesticide concentrations in 36 agricultural streams in Waikato, Canterbury, Otago and Southland during a period of stable stream flows in Austral summer 2017/18. We employed a new approach for calculating site-specific POCIS sampling rates. We also tested two novel passive samplers designed to reduce the effects of hydrodynamic conditions on sampling rates: the 'Organic-Diffusive Gradients in Thin Films' (o-DGT) aquatic passive sampler and microporous polyethylene tubes (MPTs) filled with Strata-X sorbent. Multiple pesticides were found at most sites; two or more were detected at 78% of sites, three or more at 69% of sites, and four or more at 39% of sites. Chlorpyrifos concentrations were the highest, with a maximum concentration of 180 ng/L. Concentrations of the other pesticides were generally below 20 ng/L. Mean concentrations of individual pesticides were not correlated with in-stream nutrient concentrations. The majority of pesticides were detected most frequently in POCIS, presumably due to its higher sampling rate and the relatively low concentrations of these pesticides. In contrast, chlorpyrifos was most frequently detected in grab samples. Chlorpyrifos concentrations at two sites were above the 21-day chronic 'No Observable Effect Concentration' (NOEC) values for fish and another two sites had concentrations greater than 50% of the NOEC. Otherwise, concentrations were well-below NOEC values, but close to the New Zealand Environmental Exposure Limits in several cases.


Assuntos
Clorpirifos/análise , Monitoramento Ambiental/métodos , Água Subterrânea/química , Praguicidas/análise , Rios/química , Poluentes Químicos da Água/análise , Agricultura , Nova Zelândia , Estações do Ano
12.
Environ Toxicol Chem ; 38(11): 2459-2471, 2019 11.
Artigo em Inglês | MEDLINE | ID: mdl-31373707

RESUMO

Neonicotinoid insecticides have been shown to have high chronic toxicity relative to acute toxicity, and therefore short-term toxicity tests ≤96 h in duration may underestimate their environmental risks. Among nontarget aquatic invertebrates, insects of the orders Diptera and Ephemeroptera have been found to be the most sensitive to neonicotinoids. To undertake a more accurate assessment of the risks posed by neonicotinoids to freshwater ecosystems, more data are needed from long-term tests employing the most sensitive taxa. Using nymphs of the common New Zealand mayfly genus Deleatidium spp., we performed 28-d static-renewal exposures with the widely used neonicotinoids imidacloprid, clothianidin, and thiamethoxam. We monitored survival, immobility, impairment, and mayfly moulting propensity at varying time points throughout the experiment. Imidacloprid and clothianidin exerted strong chronic toxicity effects on Deleatidium nymphs, with 28-d median lethal concentrations (LC50s) of 0.28 and 1.36 µg/L, respectively, whereas thiamethoxam was the least toxic, with a 28-d LC50 > 4 µg/L (highest concentration tested). Mayfly moulting propensity was also negatively affected by clothianidin (during 3 of 4 wk), imidacloprid (2 of 4 wk), and thiamethoxam (1 of 4 wk). Comparisons with published neonicotinoid chronic toxicity data for other mayfly taxa and larvae of the midge genus Chironomus showed similar sensitivities for mayflies and midges, suggesting that experiments using these taxa provide reliable assessments of the threats of neonicotinoids to the most vulnerable freshwater species. Environ Toxicol Chem 2019;38:2459-2471. © 2019 SETAC.


Assuntos
Ephemeroptera/efeitos dos fármacos , Neonicotinoides/toxicidade , Testes de Toxicidade Crônica , Animais , Exposição Ambiental/análise , Guanidinas/toxicidade , Inseticidas/toxicidade , Modelos Lineares , Muda/efeitos dos fármacos , Nova Zelândia , Nitrocompostos/toxicidade , Ninfa/efeitos dos fármacos , Análise de Sobrevida , Tiametoxam/toxicidade , Tiazóis/toxicidade , Poluentes Químicos da Água/toxicidade
13.
Environ Sci Technol ; 51(20): 11752-11760, 2017 Oct 17.
Artigo em Inglês | MEDLINE | ID: mdl-28925251

RESUMO

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.


Assuntos
Camada de Gelo , Modelos Teóricos , Praguicidas , Lagos , Multimídia , Nova Zelândia
14.
Environ Pollut ; 219: 253-261, 2016 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-27814542

RESUMO

Concentrations of halogenated pesticides in freshwater fish can be affected by age, size, trophic position, and exposure history. Exposure history may vary for individual fish caught at a single location due to different life histories, e.g. they may have hatched in different tributaries before migrating to a specific lake. We evaluated correlations of pesticide concentrations in freshwater brown trout (Salmo trutta) from the Clutha River, New Zealand, with potential predictors including capture site, age, length, trophic level, and life history. Life history was determined from otolith (fish ear bone) strontium isotope signatures, which vary among tributaries in the region of our study. Variability in pesticide concentrations between individual fish was not well explained by capture site, age, length, or trophic level. However, hexachlorobenzene (HCB) and chlorpyrifos concentrations were distinct in lake-based trout with different life histories. Additionally, one of the riverine life histories was associated with relatively high concentrations of total endosulfans. Linear models that included all potential predictor variables were evaluated and the resulting best models for HCB, chlorpyrifos, and total endosulfans included life history. These findings show that in cases where otolith isotope signatures vary geographically, they can be used to help explain contaminant concentration variations in fish caught from a single location.


Assuntos
Água Doce , Praguicidas/análise , Truta/crescimento & desenvolvimento , Truta/metabolismo , Poluentes Químicos da Água/análise , Animais , Endossulfano/análise , Monitoramento Ambiental , Água Doce/química , Hexaclorobenzeno/análise , Estágios do Ciclo de Vida , Nova Zelândia , Membrana dos Otólitos/química , Praguicidas/metabolismo , Rios/química , Isótopos de Estrôncio/análise , Truta/anatomia & histologia , Poluentes Químicos da Água/metabolismo
15.
Environ Sci Process Impacts ; 18(10): 1274-1284, 2016 Oct 12.
Artigo em Inglês | MEDLINE | ID: mdl-27602544

RESUMO

Brominated flame-retardants (BFRs) can be released from consumer products, resulting in accumulation in the surrounding environment and/or long-range transport to remote environments. We evaluated concentration changes in a suite of BFRs, including 13 polybrominated diphenyl ethers (PBDEs) and 1,2-bis(2,4,6-tribromophenoxy)ethane (BTBPE), in air at Toolik Lake, Arctic Alaska during the Northern Hemisphere summer of 2013. A high-volume active air sampler was used to collect 2 day integrated samples at the field station and three flow-through air samplers were used to collect 18 day integrated samples along a transect extending away from the field station. The BDE congeners associated with the penta-BDE commercial mixture (BDE-47, -99, and -100) were the most frequently detected BFRs and were found at concentrations consistent with those reported at other Arctic sites. Gas-particle distributions were influenced by temperature and correlations between gas-phase concentrations and temperature suggested that either volatilization from local sources or re-emission from secondary sources (that is, re-volatilization of BFRs that had migrated northwards from distant sources) was important for the lower-brominated BFRs during the warmer months. Source indicator analysis suggested no single dominant geographic source of BFRs while results from the flow-through samplers indicated that the field station itself was not a significant source of BFRs.


Assuntos
Poluentes Atmosféricos/análise , Bromobenzenos/análise , Retardadores de Chama/análise , Éteres Difenil Halogenados/análise , Alaska , Regiões Árticas , Monitoramento Ambiental , Lagos
16.
J Chem Ecol ; 42(2): 127-38, 2016 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-26872472

RESUMO

Chlorpyrifos is an organophosphate pesticide used around the world to protect food crops against insects and mites. Despite guidelines for chlorpyrifos usage, including precautions to protect beneficial insects, such as honeybees from spray drift, this pesticide has been detected in bees in various countries, indicating that exposure still occurs. Here, we examined chlorpyrifos levels in bees collected from 17 locations in Otago, New Zealand, and compared doses of this pesticide that cause sub-lethal effects on learning performance under laboratory conditions with amounts of chlorpyrifos detected in the bees in the field. The pesticide was detected at 17 % of the sites sampled and in 12 % of the colonies examined. Amounts detected ranged from 35 to 286 pg.bee(-1), far below the LD50 of ~100 ng.bee(-1). We detected no adverse effect of chlorpyrifos on aversive learning, but the formation and retrieval of appetitive olfactory memories was severely affected. Chlorpyrifos fed to bees in amounts several orders of magnitude lower than the LD50, and also lower than levels detected in bees, was found to slow appetitive learning and reduce the specificity of memory recall. As learning and memory play a central role in the behavioral ecology and communication of foraging bees, chlorpyrifos, even in sublethal doses, may threaten the success and survival of this important insect pollinator.


Assuntos
Abelhas/metabolismo , Comportamento Animal , Clorpirifos/metabolismo , Inseticidas/farmacologia , Aprendizagem/efeitos dos fármacos , Odorantes , Animais , Abelhas/fisiologia , Clorpirifos/farmacologia
17.
Environ Sci Technol ; 49(17): 10431-9, 2015 Sep 01.
Artigo em Inglês | MEDLINE | ID: mdl-26258946

RESUMO

Soil-air partition coefficient (Ksoil-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 Ksoil-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 Ksoil-air values of 22 semivolatile current- and historic-use pesticides and their degradation products. Ksoil-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 Ksoil-air measurements were made. Measured values were used to derive a predictive equation for pesticide Ksoil-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 Ksoil-air predictive equation and a previously described pesticide volatilization model, were compared to previous results and showed that the choice of Ksoil-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.


Assuntos
Ar , Umidade , Laboratórios , Modelos Teóricos , Praguicidas/análise , Solo/química , Temperatura , Modelos Lineares , Poluentes do Solo/análise , Volatilização
18.
Environ Sci Technol ; 48(19): 11294-301, 2014 Oct 07.
Artigo em Inglês | MEDLINE | ID: mdl-25153782

RESUMO

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.


Assuntos
Monitoramento Ambiental/métodos , Hidrocarbonetos Policíclicos Aromáticos/análise , Poluentes Químicos da Água/análise , Meteorologia , Nova Zelândia , Chuva , Neve
19.
Environ Sci Technol ; 48(9): 4852-9, 2014 May 06.
Artigo em Inglês | MEDLINE | ID: mdl-24679342

RESUMO

Polybrominated diphenyl ethers (PBDEs) are a class of brominated flame retardant that is distally transported to the Arctic. Little is known about the fate of PBDEs in Arctic surface waters, especially in the presence of dissolved organic matter (DOM). DOM has been shown to interact with hydrophobic organic contaminants and can alter their mobility, bioavailability, and degradation in the environment. In this study, the partitioning of six PBDE congeners between Arctic DOM (isolated via solid phase extraction) and water was measured using the aqueous solubility enhancement method. Measured dissolved organic carbon (DOC)-water partition coefficient (KDOC) values were nearly an order of magnitude lower than previously reported values for the same PBDE congeners in soil or commercial organic matter, ranging from 10(3.97) to 10(5.16) L kg(-1) of organic carbon. Measured results compared favorably with values calculated using polyparameter linear free energy models for Suwannee River fulvic acid. Log KDOC values increased with increasing PBDE hydrophobicity. Slightly lower than expected values were observed for the highest brominated congeners, which we attribute to steric hindrance. This study is the first to comprehensively measure KDOC values for a range of PBDE congeners with DOM isolated from Arctic surface waters.


Assuntos
Retardadores de Chama/isolamento & purificação , Éteres Difenil Halogenados/isolamento & purificação , Poluentes Químicos da Água/isolamento & purificação , Regiões Árticas , Cromatografia Gasosa , Monitoramento Ambiental/métodos , Retardadores de Chama/análise , Éteres Difenil Halogenados/análise , Solubilidade , Poluentes Químicos da Água/análise
20.
Environ Sci Process Impacts ; 16(3): 422-32, 2014 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-24365971

RESUMO

Pesticide volatilisation and subsequent vapour drift reduce a pesticide's efficiency and contribute to environmental contamination. High-volume air samplers (HVSs) are often used to measure pesticide concentrations in air but these samplers are expensive to purchase and require network electricity, limiting the number and type of sites where they can be deployed. The flow-through sampler (FTS) presents an opportunity to overcome these limitations. The FTS is a wind-driven passive sampler that has been developed to quantify organic contaminants in remote ecosystems. FTSs differ from other passive samplers in that they turn into the wind and use the wind to draw air through the sampling media. The main objective of this work was to evaluate the FTS in a near-field pesticide vapour drift study by comparing the concentrations of pyrimethanil in air measured using one HVS and three FTSs placed in the same location. Pyrimethanil was sprayed onto a vineyard as part of normal pest management procedures. Air samples were collected every eight hours for 48 h. The volume of air sampled by the FTSs was calculated using the measured relationship between ambient wind speed and the wind speed inside the sampler as determined with a separate wind tunnel study. The FTSs sampled 1.7 to 40.6 m(3) of air during each 8 h sampling period, depending on wind speed, whereas the mean volume sampled by the HVS was 128.7 m(3). Mean pyrimethanil concentrations ranged from 0.4 to 3.2 µg m(-3) of air. Inter-sampler reproducibility, as represented by percent relative standard deviation, for the three FTSs was ∼20%. The largest difference in FTS-derived versus HVS-derived pyrimethanil concentrations occurred during the lowest wind-speed period. During this period, it is likely that the FTS predominately acted like a traditional diffusion-based passive sampler. As indicated by both types of sampler, pyrimethanil concentrations in air changed by a factor of ∼2 during the two days after spaying. This work shows that the FTS has good potential for use in near-field vapour drift studies and that FTS technology could make multi-sampler experimental designs more feasible.


Assuntos
Poluentes Atmosféricos/análise , Monitoramento Ambiental/instrumentação , Modelos Químicos , Praguicidas/análise , Pirimidinas/análise , Monitoramento Ambiental/métodos , Tamanho da Partícula , Reprodutibilidade dos Testes , Vento
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