132 results on '"Kah, Melanie"'
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2. Environmentally relevant concentrations of microplastics from agricultural mulch and cadmium negatively impact earthworms by triggering neurotoxicity and disrupting homeostasis
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Jiang, Xiaofeng, Wang, Xinwei, Kah, Melanie, and Li, Mei
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- 2024
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3. Testing methods to estimate population size for wastewater treatment plants using census data: Implications for wastewater-based epidemiology
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Price, Mackay, Tscharke, Ben, Chappell, Andrew, Kah, Melanie, Sila-Nowicka, Katarzyna, Morris, Helen, Ward, Daniel, and Trowsdale, Sam
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- 2024
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4. Public perceptions of per- and polyfluoroalkyl substances (PFAS): Psycho-demographic characteristics differentiating PFAS knowledge and concern
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Kemper, Joya A., Sharp, Emma, Yi, Shan, Leitao, Erin M., Padhye, Lokesh P., Kah, Melanie, Chen, Jack L.-Y., and Gobindlal, Kapish
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- 2024
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5. Formation of disinfection by-products from microplastics, tire wear particles, and other polymer-based materials
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Ghanadi, Mahyar, Kah, Melanie, Kookana, Rai S., and Padhye, Lokesh P.
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- 2023
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6. Environmental risks and the potential benefits of nanopesticides: a review
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Xu, Zhenlan, Tang, Tao, Lin, Qin, Yu, Jianzhong, Zhang, Changpeng, Zhao, Xueping, Kah, Melanie, and Li, Lingxiangyu
- Published
- 2022
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7. Hopeful Approaches to Teaching and Learning Environmental 'Wicked Problems'
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Sharp, Emma L., Fagan, Joseph, Kah, Melanie, McEntee, Marie, and Salmond, Jennifer
- Abstract
"Wicked problems" are complex to understand and challenging to teach. Our experience of teaching about environmental concerns in Aotearoa New Zealand suggests how these concepts are taught is more important for student learning than the nature of wicked problems themselves. By offering opportunities for students to co-develop their own situated knowledges about wicked problems, they can conceptualise and tackle them more effectively at their own pace and in their own experiential contexts. Here we identify and discuss approaches to teaching and learning that can be effectively applied to any wicked problem. We demonstrate a hopeful way to teach and learn about unwieldy and overwhelming issues that many of today's undergraduates will inevitably be expected to confront in the future. This paper provides a framework to engage students in a course, and tools for engendering active participation in situated and tangible learning experiences when teaching wicked problems. As lecturers teaching in a School of Environment in the disciplinary areas of geography, environmental science, science communication, and sustainability, we discuss the value and applications of these ideas across three levels of undergraduate teaching. We identify challenges that we have experienced and show how it is possible to turn these challenges into opportunities.
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- 2021
- Full Text
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8. Occurrence and fate of poly- and perfluoroalkyl substances (PFAS) in urban waters of New Zealand
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Lenka, Swadhina Priyadarshini, Kah, Melanie, and Padhye, Lokesh P.
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- 2022
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9. A review of the occurrence, transformation, and removal of poly- and perfluoroalkyl substances (PFAS) in wastewater treatment plants
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Lenka, Swadhina Priyadarshini, Kah, Melanie, and Padhye, Lokesh P.
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- 2021
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10. Comprehensive framework for human health risk assessment of nanopesticides
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Kah, Melanie, Johnston, Linda J., Kookana, Rai S., Bruce, Wendy, Haase, Andrea, Ritz, Vera, Dinglasan, Jordan, Doak, Shareen, Garelick, Hemda, and Gubala, Vladimir
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- 2021
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11. Adsorption mechanisms of short-chain and ultrashort-chain PFAS on anion exchange resins and activated carbon.
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Lenka, Swadhina P., Kah, Melanie, Chen, Jack L.-Y., Tiban-Anrango, Bryan Andres, and Padhye, Lokesh P.
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- 2024
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12. Release and stability of two tebuconazole nanoformulations in different aquatic media.
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López-Cabeza, Rocío, Eghbalinejad, Mahleh, Kah, Melanie, Grillo, Renato, Bílková, Zuzana, Kotouček, Jan, and Hofman, Jakub
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- 2024
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13. Nano-enabled strategies to enhance crop nutrition and protection
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Kah, Melanie, Tufenkji, Nathalie, and White, Jason C.
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- 2019
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14. Sorption of ionizable and ionic organic compounds to biochar, activated carbon and other carbonaceous materials
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Kah, Melanie, Sigmund, Gabriel, Xiao, Feng, and Hofmann, Thilo
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- 2017
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15. A critical evaluation of nanopesticides and nanofertilizers against their conventional analogues
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Kah, Melanie, Kookana, Rai Singh, Gogos, Alexander, and Bucheli, Thomas Daniel
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- 2018
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16. Pyrolysis of waste materials: Characterization and prediction of sorption potential across a wide range of mineral contents and pyrolysis temperatures
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Kah, Melanie, Sun, Huichao, Sigmund, Gabriel, Hüffer, Thorsten, and Hofmann, Thilo
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- 2016
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17. 4 - Nanopesticides—modes of action and impacts
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da Silva Pontes, Montcharles, de Lima Forini, Mariana Monteiro, Caires, Anderson Rodrigues Lima, Santiago, Etenaldo Felipe, Tripathi, Durgesh Kumar, Kah, Melanie, and Grillo, Renato
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- 2023
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18. Analysing the fate of nanopesticides in soil and the applicability of regulatory protocols using a polymer-based nanoformulation of atrazine
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Kah, Melanie, Machinski, Patrick, Koerner, Petra, Tiede, Karen, Grillo, Renato, Fraceto, Leonardo Fernandes, and Hofmann, Thilo
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- 2014
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19. Nanotechnology as a foundational tool to combat global food insecurity
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Kah, Melanie, Sabliov, Cristina, Wang, Yi, and White, Jason C.
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- 2023
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20. Tebuconazole and terbuthylazine encapsulated in nanocarriers: preparation, characterization and release kinetics.
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López-Cabeza, Rocío, Kah, Melanie, Grillo, Renato, Koutný, Marek, Salač, Jan, Bílková, Zuzana, Eghbalinejad, Mahleh, and Hofman, Jakub
- Published
- 2022
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21. Environmental fate of nanopesticides: durability, sorption and photodegradation of nanoformulated clothianidin† †Electronic supplementary information (ESI) available. See DOI: 10.1039/c8en00038g
- Author
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Kah, Melanie, Walch, Helene, and Hofmann, Thilo
- Subjects
Chemistry - Abstract
A lot of research efforts are currently dedicated to the development of nano-enabled agrochemicals. It is thus urgent to develop suitable strategies for their ecological assessment., A lot of research efforts are currently dedicated to the development of nano-enabled agrochemicals. Knowledge about their environmental behaviour is however scarce, which impedes the assessment of the new risk and benefits relative to currently used agrochemicals. With the aim to advance our understanding of the fate of nanopesticides in the environment and support the development of robust exposure assessment procedures, the main objectives of the study were to (i) investigate the extent to which three nanoformulations can affect the photodegradation and sorption of the insecticide clothianidin, and (ii) evaluate various approaches to estimate durability, a key parameter for the exposure assessment of nanopesticides. The nanoformulations increased the photodegradation half-life in water by a maximum of 21% relative to the conventional formulation. Sorption to soil was investigated by two methods and over time, and results show that sorption was increased by up to 51% and 10%, relative to unformulated clothianidin and the commercial formulation, respectively. Our results generally indicate that nanoformulations may have a greater impact on the fate of pesticide active ingredients than commercial formulations. It is important to note however that differences in fate parameters were generally very moderate, including in realistic worst-case conditions (high pesticide concentration and ionic strength). Our results collectively suggest that clothianidin was rapidly released from the nanocarrier systems and that the durability of the three nanoformulations would be short in water as well as in soil environments (including under realistic soil to solution ratio). The durability of nanoformulations after their application in the environment is an essential parameter that needs to be characterised for the development as well as for the evaluation of nano-enabled agrochemicals. This study illustrates how performances of nano-enabled products can be critically benchmarked against existing products to support an objective assessment of new environmental risks and benefits. In this context, the fate of the nanocarrier system is of great interest and should be the topic of further research.
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- 2018
22. List of contributors
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Adeel, Muhammad, Afantitis, Antreas, Ahmad, Muhammad Arslan, Anderson, Anne J., Avellan, Astrid, Azeem, Imran, Borgatta, Jaya, Britt, David W., Caires, Anderson Rodrigues Lima, Cerbu, Constantin, Chadwick, J.J., Clark, Nathaniel J., Cota-Ruiz, Keni, da Silva Pontes, Montcharles, Danai-Varsou, Dimitra, de Lima Forini, Mariana Monteiro, Dimkpa, Christian O., Dong, Chaonan, Dunn, Patrick J., Elmer, Wade, Fu, Chengcheng, Gilbertson, Leanne M., Grillo, Renato, Guo, Zhiling, Handy, Richard D., Hou, Jie, Jiao, Chunlei, Kah, Melanie, Karmous, Inès, Khan, Mohammad Nauman, Khan, Zaid, L. Gardea-Torresdey, Jorge, Li, Jiaqi, Li, Yanhui, Lin, Daohui, Lowry, Gregory V., Lynch, Iseult, Ma, Xingmao, Ma, Yuhui, Mano, João, Melagraki, Georgia, Miranda, Matheus, Morais, Bruno, Oliveira, Mariana, Pourzahedi, Leila, Rodrigues, Sandra, Rodrigues, Sónia M., Rui, Yukui, Sabliov, Cristina M., Salvador, Diana, Santiago, Etenaldo Felipe, Santra, Swadeshmukul, Shakoor, Noman, Shi, Honglan, Smith, Stephen L., Theis, Thomas L., Tripathi, Durgesh Kumar, Ullah, S., Vassallo, Joanne, Wang, Xiaoxuan, White, Jason C., Witteveen, A., Wu, Honghong, Wu, Ting, Xu, Ming, Yang, Fang, Yang, John, Ye, Yuqing, Youssef, Naglaa, Zain, Muhammad, Zhang, Peng, Zhang, Zhiyong, Zhao, Xuepeng, and Zhu, Lan
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- 2023
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23. Fate of copper in soil: effect of agrochemical (nano)formulations and soil properties.
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Kah, Melanie, Navarro, Divina, Schenkeveld, Walter, Kookana, Rai S., Kirby, Jason K., Santra, Swadeshmukul, and Ozcan, Ali
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- 2022
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24. International Analysis of Sources and Human Health Risk Associated with Trace Metal Contaminants in Residential Indoor Dust.
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Faye Isley, Cynthia, Fry, Kara L., Xiaochi Liu, Michael Filippelli, Gabriel, Entwistle, Jane A., Martin, Adam P., Kah, Melanie, Meza-Figueroa, Diana, Shukle, John T., Jabeen, Khadija, Famuyiwa, Abimbola O., Liqin Wu, Sharifi-Soltani, Neda, Doyi, Israel N. Y., Argyraki, Ariadne, Kin Fai Ho, Chenyin Dong, Gunkel-Grillon, Peggy, Marjorie Aelion, C., and Patrick Taylor, Mark
- Published
- 2022
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25. Hopeful approaches to teaching and learning environmental "wicked problems".
- Author
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Sharp, Emma L., Fagan, Joseph, Kah, Melanie, McEntee, Marie, and Salmond, Jennifer
- Subjects
ENVIRONMENTAL education ,TEACHING ,LEARNING ,SAFE spaces in education ,EXPERIENTIAL learning ,YOUNG adults ,HIGHER education - Abstract
"Wicked problems" are complex to understand and challenging to teach. Our experience of teaching about environmental concerns in Aotearoa New Zealand suggests how these concepts are taught is more important for student learning than the nature of wicked problems themselves. By offering opportunities for students to co-develop their own situated knowledges about wicked problems, they can conceptualise and tackle them more effectively at their own pace and in their own experiential contexts. Here we identify and discuss approaches to teaching and learning that can be effectively applied to any wicked problem. We demonstrate a hopeful way to teach and learn about unwieldy and overwhelming issues that many of today's undergraduates will inevitably be expected to confront in the future. This paper provides aframework to engage students in acourse, and tools for engendering active participation insituated and tangible learning experiences when teaching wicked problems. As lecturers teaching in aSchool of Environment in the disciplinary areas of geography, environmental science, science communication, and sustainability, we discuss the value and applications of these ideas across three levels of undergraduate teaching. We identify challenges that we have experienced and show how it is possible to turn these challenges into opportunities. [ABSTRACT FROM AUTHOR]
- Published
- 2021
- Full Text
- View/download PDF
26. Is centrifugal ultrafiltration a robust method for determining encapsulation efficiency of pesticide nanoformulations?
- Author
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López-Cabeza, Rocío, Kah, Melanie, Grillo, Renato, Bílková, Zuzana, and Hofman, Jakub
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- 2021
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27. Emerging investigator series: nanotechnology to develop novel agrochemicals: critical issues to consider in the global agricultural context.
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Kah, Melanie and Kookana, Rai
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- 2020
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28. Nanopesticides and nanofertilizers: emerging contaminants or opportunities for risk mitigation?
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Kah, Melanie
- Subjects
lcsh:Chemistry ,Chemistry ,plant protection product ,lcsh:QD1-999 ,Nanoformulation ,Perspective ,Agrochemical ,Nanotechnology ,Agriculture ,environment ,risk - Abstract
Research into nanotechnology applications for use in agriculture has become increasingly popular over the past decade, with a particular interest in developing novel nanoagrochemicals in the form of so-called "nanopesticides" and "nanofertilizers." In view of the extensive body of scientific literature available on the topic, many authors have foreseen a revolution in current agricultural practices. This perspective integrates scientific, regulatory, public and commercial viewpoints, and aims at critically evaluating progress made over the last decade. A number of key (and sometimes controversial) questions are addressed with the aim of identifying the products that will soon emerge on the market and analyzing how they can fit into current regulatory and commercial frameworks. Issues related to the differences in definitions and perceptions within different sectors are discussed, as well as our current ability to assess new risks and benefits relative to conventional products. Many nanoagrochemicals resemble products used currently, which raises the question whether the effect of formulation has been sufficiently taken into account when evaluating agrochemicals. This analysis identifies directions for future research and regulatory needs in order to encourage intelligent design and promote the development of more sustainable agrochemicals.
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- 2015
29. Copper toxicity to Folsomia candida in different soils: a comparison between nano and conventional formulations.
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Neves, Joana, Cardoso, Diogo N., Malheiro, Catarina, Kah, Melanie, Soares, Amadeu M. V. M., Wrona, Frederick J., and Loureiro, Susana
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ENVIRONMENTAL risk assessment ,CANDIDA ,PLANT diseases ,COPPER compounds ,SOILS ,SOIL salinity - Abstract
Environmental context: Nanotechnology has great potential for managing agricultural plant disease. This study compares effects of various nano and conventional copper formulations on Collembola Folsomia candida , a model arthropod often used to test soil pollutants. Although toxicity varied between formulations, with a nanopesticide showing one of the highest toxicities, the differences were mainly due to the active copper compound rather than its nano formulation. Nanotechnology has recently become a major asset in agricultural practices owing to the improvement and provision of solutions for plant disease management, especially in the form of nanopesticides. These products are considered as one of the main direct sources of nanomaterials in terrestrial ecosystems, and for that reason, it is essential to understand and evaluate their behaviour and toxicity in the environment. In addition, the panoply of similar compounds makes it difficult to accurately evaluate if different formulations may induce different effects on non-target organisms. We aim to compare the toxicity and bioavailability of different copper formulations (nano and non-nano) applied to the soil using the model organism Folsomia candida. Reproduction tests were performed in two different soils (Lufa 2.1 and 2.2) with two equilibrium times after spiking (0 and 48 h). Depending on the copper form present in the formulation, the half maximal effective concentration (EC
50 ) values of the non-nano pesticides varied from 274 mg Cu kg−1 in Champion® to 3030 mg Cu kg−1 in Cupravit® in Lufa 2.2 and 48 h equilibrium. The nano formulation displayed one of the highest toxicities to collembolans, with an EC50 of 156 mg Cu kg−1 . Regarding the soil type, a higher toxicity in Lufa 2.1 was observed probably related to the soil characteristics, namely lower pH and lower organic content, which increase the metal solubility and consequently the bioavailability. The only exception was the nanopesticide Kocide 3000®, whose toxicity was higher in Lufa 2.2. This study emphasises the importance of understanding the links between metal bioavailability and toxicity to support the more robust environmental risk assessment of different Cu fungicide formulations. Environmental context. Nanotechnology has great potential for managing agricultural plant disease. This study compares effects of various nano and conventional copper formulations on Collembola Folsomia candida , a model arthropod often used to test soil pollutants. Although toxicity varied between formulations, with a nanopesticide showing one of the highest toxicities, the differences were mainly due to the active copper compound rather than its nano formulation. [ABSTRACT FROM AUTHOR]- Published
- 2019
- Full Text
- View/download PDF
30. Nanoformulations can significantly affect pesticide degradation and uptake by earthworms and plants.
- Author
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Fojtová, Dana, Vašíčková, Jana, Grillo, Renato, Bílková, Zuzana, Šimek, Zdeněk, Neuwirthová, Natália, Kah, Melanie, and Hofman, Jakub
- Subjects
PESTICIDES ,BIOACCUMULATION in plants ,ORGANOPHOSPHORUS pesticides ,EARTHWORMS ,TEBUCONAZOLE ,ENVIRONMENTAL literacy ,LETTUCE - Abstract
Environmental context: Nanopesticides are increasingly being developed for agricultural use, but knowledge concerning their environmental fate and effects is limited. This microcosm study brings new results about soil fate and bioaccumulation of polymeric or lipid nanoparticles carrying chlorpyrifos or tebuconazole. The nanoformulations significantly altered the fate and bioavailability of the pesticides in soil even under the real-world and complex conditions of microcosms. An increasing number of nanoformulated pesticides (nanopesticides) have been developed in recent years with the aim to improve pesticide efficiencies and reduce their impact on the environment and human health. However, knowledge about their environmental fate and effects is still very limited. This study compares the soil fate and bioaccumulation of four model nanopesticides (chlorpyrifos and tebuconazole loaded on polymeric and lipid nanocarriers) relative to the conventional formulations and pure active ingredients (all added at 0.5 mg kg
−1 ) in microcosms containing earthworms Eisenia fetida and lettuce Lactuca sativa in two soils (LUFA 2.1 and 2.4) over a period of four months. The nanoformulations increased the soil half-life of the pesticides by up to 2 times (e.g. chlorpyrifos with lipid nanocarrier and tebuconazole with polymeric nanocarrier in LUFA 2.1), probably as a direct consequence of the slow release of the pesticide from the nanocarriers. Pesticide bioaccumulation in earthworms was often increased for the nanopesticides probably as a result of their enhanced bioavailability. The nanoformulations were also shown to affect the pesticide bioaccumulation in plants, but trends were inconsistent. Overall, the microcosm results demonstrated that nanoformulations can significantly alter the fate and bioavailability of pesticides. However, generalisations were difficult to make as the impacts depended on the type of nanocarrier, pesticide, soil used and time scale. We believe that our study contributes towards the critical mass of case studies needed to enable a judging of the benefits versus risks of nanopesticides. Environmental context. Nanopesticides are increasingly being developed for agricultural use, but knowledge concerning their environmental fate and effects is limited. This microcosm study brings new results about soil fate and bioaccumulation of polymeric or lipid nanoparticles carrying chlorpyrifos or tebuconazole. The nanoformulations significantly altered the fate and bioavailability of the pesticides in soil even under the real-world and complex conditions of microcosms. [ABSTRACT FROM AUTHOR]- Published
- 2019
- Full Text
- View/download PDF
31. Impact of (nano)formulations on the distribution and wash-off of copper pesticides and fertilisers applied on citrus leaves.
- Author
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Kah, Melanie, Navarro, Divina, Kookana, Rai S., Kirby, Jason K., Santra, Swadeshmukul, Ozcan, Ali, and Kabiri, Shervin
- Subjects
FERTILIZERS ,PESTICIDES ,LEAVES ,CITRUS ,GRAPHENE oxide ,BIOPESTICIDES - Abstract
Environmental context: There are great concerns around current wide usage of copper-based agrochemicals. We compare the fate of nano- and conventional forms of copper, in particular their resistance to wash-off by rain (rainfastness), following their application to citrus leaves. Results showing large differences between the formulations in the amount and forms of copper washed from the leaves provide essential information to optimise agrochemical efficacy while minimising the environmental impact. This study compares the rainfastness of nine forms of Cu, including nano and conventional Cu-based fungicide formulations, as well as their salt or bulk equivalents. Rainfastness is the ability to resist wash-off; it is a key property for improving pesticide formulations and for assessing the potential transfer of pesticides to the soil. A new protocol was developed to characterise losses of Cu from treated leaves. It consisted of dipping the leaves in rainwater and then in an acid/ethanol mixture followed by size fractionation. The proportion of Cu lost by wash-off from citrus leaves ranged from <2 % (Tribasic, nCuO or Cu(OH)
2 ) up to 93 % (CuSO4 ) of the initial amount of Cu applied. Intermediate Cu losses were observed for formulations with silica (nano)particles (9–14 % of applied Cu), Kocide (22 %), ChampDP (31 %), and a formulation with graphene oxide (47 %). Smaller particles generally resulted in less wash-off, possibly due to stronger attachment to the leaf surface, but other factors such as the particle shape and solubility also played an essential role. The retention of nCuO to the leaves was particularly high, and the exact mechanisms involved (e.g. foliar uptake) deserve further work. Most of the Cu was washed off in its ionic form (>74 %). Two Cu formulations (one commercial formulation and the formulation with graphene oxide) also showed wash off in significant proportions of Cu (~17 %) in the nano-sized fraction. This study provides essential information on the amounts and forms of Cu that may reach the soil after the application of Cu-based agrochemicals. The great diversity in behaviour across the range of formulations considered highlights the need for more systematic research to fully exploit the potential improvements of current agrochemicals through (nano)formulation technologies. Environmental context. There are great concerns around current wide usage of copper-based agrochemicals. We compare the fate of nano- and conventional forms of copper, in particular their resistance to wash-off by rain (rainfastness), following their application to citrus leaves. Results showing large differences between the formulations in the amount and forms of copper washed from the leaves provide essential information to optimise agrochemical efficacy while minimising the environmental impact. [ABSTRACT FROM AUTHOR]- Published
- 2019
- Full Text
- View/download PDF
32. Are Nanoparticles a Threat to Mycorrhizal and Rhizobial Symbioses? A Critical Review.
- Author
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Tian, Hui, Kah, Melanie, and Kariman, Khalil
- Subjects
SYMBIOSIS ,POISONS ,SOIL microbiology ,ECTOMYCORRHIZAS ,NANOPARTICLES ,LITERATURE reviews - Abstract
Soil microorganisms can be exposed to, and affected by, nanoparticles (NPs) that are either purposely released into the environment (e.g., nanoagrochemicals and NP-containing amendments) or reach soil as nanomaterial contaminants. It is crucial to evaluate the potential impact of NPs on key plant-microbe symbioses such as mycorrhizas and rhizobia, which are vital for health, functioning and sustainability of both natural and agricultural ecosystems. Our critical review of the literature indicates that NPs may have neutral, negative, or positive effects on development of mycorrhizal and rhizobial symbioses. The net effect of NPs on mycorrhizal development is driven by various factors including NPs type, speciation, size, concentration, fungal species, and soil physicochemical properties. As expected for potentially toxic substances, NPs concentration was found to be the most critical factor determining the toxicity of NPs against mycorrhizas, as even less toxic NPs such as ZnO NPs can be inhibitory at high concentrations, and highly toxic NPs such as Ag NPs can be stimulatory at low concentrations. Likewise, rhizobia show differential responses to NPs depending on the NPs concentration and the properties of NPs, rhizobia, and growth substrate, however, most rhizobial studies have been conducted in soil-less media, and the documented effects cannot be simply interpreted within soil systems in which complex interactions occur. Overall, most studies indicating adverse effects of NPs on mycorrhizas and rhizobia have been performed using either unrealistically high NP concentrations that are unlikely to occur in soil, or simple soil-less media (e.g., hydroponic cultures) that provide limited information about the processes occurring in the real environment/agrosystems. To safeguard these ecologically paramount associations, along with other ecotoxicological considerations, large-scale application of NPs in farming systems should be preceded by long-term field trials and requires an appropriate application rate and comprehensive (preferably case-specific) assessment of the context parameters i.e., the properties of NPs, microbial symbionts, and soil. Directions and priorities for future research are proposed based on the gaps and experimental restrictions identified. [ABSTRACT FROM AUTHOR]
- Published
- 2019
- Full Text
- View/download PDF
33. Sorption to soil, biochar and compost: is prediction to multicomponent mixtures possible based on single sorbent measurements?
- Author
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Kah, Melanie, Sigmund, Gabriel, Manga Chavez, Pedro Luis, Bielská, Lucie, and Hofmann, Thilo
- Subjects
SOIL absorption & adsorption ,COMPOSTING ,POLYCYCLIC aromatic hydrocarbons ,SOIL amendments ,BIOCHAR - Abstract
Amendment with biochar and/or compost has been proposed as a strategy to remediate soil contaminated with low levels of polycyclic aromatic hydrocarbons. The strong sorption potential of biochar can help sequestering contaminants while the compost may promote their degradation. An improved understanding of how sorption evolves upon soil amendment is an essential step towards the implementation of the approach. The present study reports on the sorption of pyrene to two soils, four biochars and one compost. Detailed isotherm analyzes across a wide range of concentration confirmed that soil amendments can significantly increase the sorption of pyrene. Comparisons of data obtained by a classical batch and a passive sampling method suggest that dissolved organic matter did not play a significant role on the sorption of pyrene. The addition of 10% compost to soil led to a moderate increase in sorption (<2-fold), which could be well predicted based on measurements of sorption to the individual components. Hence, our result suggest that the sorption of pyrene to soil and compost can be relatively well approximated by an additive process. The addition of 5% biochar to soil (with or without compost) led to a major increase in the sorption of pyrene (2.5-4.7-fold), which was, however, much smaller than that suggested based on the sorption measured on the three individual components. Results suggest that the strong sorption to the biochar was attenuated by up to 80% in the presence of soil and compost, much likely due to surface and pore blockage. Results were very similar in the two soils considered, and collectively suggest that combined amendments with compost and biochar may be a useful approach to remediate soils with low levels of contamination. Further studies carried out in more realistic settings and over longer periods of time are the next step to evaluate the long term viability of remediation approaches based on biochar amendments. [ABSTRACT FROM AUTHOR]
- Published
- 2018
- Full Text
- View/download PDF
34. Bioavailability and toxicity of pyrene in soils upon biochar and compost addition.
- Author
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Bielská, Lucie, Kah, Melanie, Sigmund, Gabriel, Hofmann, Thilo, and Höss, Sebastian
- Subjects
- *
PYRENE , *BIOCHAR , *BIOAVAILABILITY , *NEMATODES , *WORMS , *REPRODUCTION - Abstract
The study investigates the role of biochar and/or compost in mitigating the toxic effects of pyrene in soils using reproduction of nematodes and porewater concentration as measures of pyrene toxicity and bioavailability, respectively. Two soils were spiked with increasing levels of pyrene to achieve a concentration-response relationship for the reproduction of Caenorhabditis elegans . The observed EC50 values (pyrene concentration causing 50% inhibition of reproduction) were 14 mg/kg and 31 mg/kg (dry mass) for these soils, corresponding to equilibrium porewater concentrations of 37 μg/L and 47 μg/L, respectively. Differences in organic carbon content were not sufficient to explain the variability in toxicity between the different soils. Soils causing a significant inhibition of reproduction were further amended with 10%-compost, 5%-biochar, or both, and the effects on reproduction and porewater concentration determined. Combined addition of compost and biochar was identified as the most effective strategy in reducing pyrene concentration in soil porewater, which was also partly reflected in soil toxicity. However, porewater concentrations predicted only 52% of pyrene toxicity to nematodes, pointing to particle-bound or dietary exposure pathways. Capsule: Amending pyrene-spiked soil with biochar and compost effectively reduced pyrene porewater concentrations and toxicity to nematodes, which were significantly related. [ABSTRACT FROM AUTHOR]
- Published
- 2017
- Full Text
- View/download PDF
35. Effect of ageing on the properties and polycyclic aromatic hydrocarbon composition of biochar.
- Author
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Sigmund, Gabriel, Bucheli, Thomas D., Hilber, Isabel, Micić, Vesna, Kah, Melanie, and Hofmann, Thilo
- Abstract
The influence of ageing on biochar properties has been investigated by comparing three fresh biochars with biochars artificially aged by either H
2 O2 thermal oxidation or horseradish peroxidase enzymatic oxidation. In addition, a field-aged counterpart for one of the biochars was recovered from an agricultural field site, four years after application. Biochar properties, including surface areas and pore volumes (derived by N2 and CO2 physisorption) and elemental compositions, showed only minor changes following both artificial and field ageing, indicating high biochar stability. Concentrations of the 16 US EPA PAHs were measured in all of the biochars and a contaminant trap was used to investigate the effect of ageing on their bioaccessibility. The concentrations of total and bioaccessible PAHs ranged from 4.4 to 22.6 mg kg−1 and 0.0 to 9.7 mg kg−1 , respectively. Concentrations of the 16 US EPA PAHs decreased following field ageing, but the proportion of low molecular weight PAHs increased. The observed changes in PAH composition with field ageing can be explained by uptake from the surrounding soil and intra-biochar transfer processes. To better understand changes in PAH composition with ageing, an additional broad range of alkylated PAHs was also analyzed in selected samples. Our results show that the tested artificial ageing protocols are unable to approximate the changes in PAH composition resulting from field ageing. Nevertheless, total and bioaccessible PAH concentrations decreased for both artificially and field-aged biochars, indicating that biochars release PAHs when they are freshly produced and that the risk of PAH release decreases with ageing. [ABSTRACT FROM AUTHOR]- Published
- 2017
- Full Text
- View/download PDF
36. Interactions between aromatic hydrocarbons and functionalized C60 fullerenes – insights from experimental data and molecular modelling.
- Author
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Hüffer, Thorsten, Sun, Huichao, Kubicki, James D., Hofmann, Thilo, and Kah, Melanie
- Published
- 2017
- Full Text
- View/download PDF
37. Impacts of (Nano)formulations on the Fate of an Insecticide in Soil and Consequences for Environmental Exposure Assessment.
- Author
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Kah, Melanie, Weniger, Anne-Kathrin, and Hofmann, Thilo
- Subjects
- *
APPLICATION of pesticides , *BIFENTHRIN , *GROUNDWATER , *INSECTICIDES , *SOIL absorption & adsorption , *NANOCARRIERS , *PESTICIDE pollution - Abstract
The development of nanopesticides has recently received an increased level of attention. However, there are very few data about the environmental fate of these new products, and it is not known whether nanoformulations can be evaluated within the current pesticide regulatory framework. Sorption and degradation parameters of the insecticide bifenthrin were measured in two soils for (i) the pure active ingredient, (ii) three nanoformulations, and (iii) a commercially available formulation. In most cases, fate parameters derived for the nanopesticides were significantly different from those derived for the pure active ingredient (factors of up to 10 for sorption and 1.8 for degradation), but discrepancies were not easy to relate to the characteristics of the nanocarriers. In some cases, differences were also observed between the commercial formulation and the pure active ingredient (factors of up to 1.4 for sorption and 1.7 for degradation). In the regulatory context, the common assumption that formulations do not influence the environmental fate of pesticide active ingredients after application seems therefore not always adequate. In the absence of direct measurement, an inverse modeling approach was successfully applied to evaluate the durability of the formulations in soil (release half-life ranged between 11 and 74 days). Predicted groundwater concentrations very much depended on the modeling approach adopted but overall suggest that the nanoformulations studied could reduce losses to groundwater. [ABSTRACT FROM AUTHOR]
- Published
- 2016
- Full Text
- View/download PDF
38. Predicting the Sorption of Aromatic Acids to Noncarbonized and Carbonized Sorbents.
- Author
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Sigmund, Gabriel, Huichao Sun, Hofmann, Thilo, and Kah, Melanie
- Published
- 2016
- Full Text
- View/download PDF
39. Projected Dietary Intake of Zinc, Copper, and Cerium from Consumption of Carrot (Daucus carota) Exposed to Metal Oxide Nanoparticles or Metal Ions.
- Author
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Ebbs, Stephen D., Bradfield, Scott J., Kumar, Pawan, White, Jason C., Xingmao Ma, Kah, Melanie, and Rico, Cyren M.
- Subjects
DIETARY supplements ,ZINC in the body ,VEGETABLE contamination ,FOOD contamination ,COMPOSITION of carrots ,PHYSIOLOGY - Abstract
The expanding production and use of engineered nanomaterials (ENMs) have raised concerns about the potential risk of those materials to food safety and human health. In a prior study, the accumulation of Zn, Cu, and Ce from ZnO, CuO, or CeO
2 , respectively, was examined in carrot (Daucus carota L.) grown in sand culture in comparison to accumulation from exposure to equivalent concentrations of ionic Zn2+ , Cu2+ , or Ce4+ . The fresh weight concentration data for peeled and unpeeled carrots were used to project dietary intake of each metal by seven age-mass classes from child to adult based on consumption of a single serving of carrot. Dietary intake was compared to the oral reference dose (oral RfD) for chronic toxicity for Zn or Cu and estimated mean and median oral RfD values for Ce based on nine other rare earth elements. Reverse dietary intake calculations were also conducted to estimate the number of servings of carrot, the mass of carrot consumed, or the tissue concentration of Zn, Cu, or Ce that would cause the oral RfD to be exceeded upon consumption. The projections indicated for Zn and Cu, the oral RfD would be exceeded in only a few highly unrealistic scenarios of exceedingly high Zn or Cu concentrations in the substrate from ZnO or CuO or consumption of excessive amounts of unpeeled carrot. The implications associated with the presence of Ce in the carrot tissues depended upon whether the mean or median oral RfD value from the rare earth elements was used as a basis for comparison. The calculations further indicated that peeling carrots reduced the projected dietary intake by one to two orders of magnitude for both ENMand ionic-treated carrots. Overall in terms of total metal concentration, the results suggested no specific impact of the ENM form on dietary intake. The effort here provided a conservative view of the potential dietary intake of these three metals that might result from consumption of carrots exposed to nanomaterials (NMs) and how peeling mitigated that dietary intake. The results also demonstrate the potential utility of dietary intake projections for examining potential risks of NM exposure from agricultural foods. [ABSTRACT FROM AUTHOR]- Published
- 2016
- Full Text
- View/download PDF
40. Contribution of household herbicide usage to glyphosate and its degradate aminomethylphosphonic acid in surface water drains.
- Author
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Ramwell, Carmel T, Kah, Melanie, and Johnson, Paul D
- Subjects
HERBICIDES ,GLYPHOSATE ,HYPOGLYCIN A ,WATER ,METROPOLITAN areas ,CHEMICAL industry - Abstract
BACKGROUND It is necessary to understand the extent to which different sources of pesticides contribute to surface water contamination in order to focus preventive measures appropriately. The extent to which glyphosate use in the home and garden sector may contribute to surface water contamination has not previously been quantified. The aim of this study was to quantify the widely used herbicide glyphosate and its degradation product aminomethylphosphonic acid ( AMPA) in surface water drains (storm drains) that could be attributed to amateur, non-professional usage alone. RESULTS Maximum glyphosate and AMPA concentrations in surface water drains were 8.99 and 1.15 µg L
−1 respectively after the first rain event following the main application period, but concentrations rapidly declined to <1.5 and <0.5 µg L−1 . The AMPA:glyphosate ratio was typically 0.35. Less than 1% of the applied glyphosate was recovered in drain water. CONCLUSION Glyphosate and AMPA losses from urban areas that arise solely from amateur usage have been quantified. In spite of overdosing occurring, glyphosate concentrations in drain flow were lower than concentrations reported elsewhere from professional use in urban areas. © 2014 Society of Chemical Industry [ABSTRACT FROM AUTHOR]- Published
- 2014
- Full Text
- View/download PDF
41. Sorption behavior of carbon nanotubes: Changes induced by functionalization, sonication and natural organic matter.
- Author
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Kah, Melanie, Zhang, Xiaoran, and Hofmann, Thilo
- Subjects
- *
DISTRIBUTION isotherms (Chromatography) , *CARBON nanotubes , *SONICATION , *ORGANIC compounds , *HUMIC acid , *SORBENTS - Abstract
The effect of functionalization on the sorption behavior of carbon nanotubes (CNTs) remains poorly understood, especially when combined with other factors affecting dispersion. The sorption behavior of a series of functionalized CNTs towards pyrene has therefore been systematically evaluated over a wide range of concentrations and dispersion scenarios. When studied as purchased (in the absence of humic acids and sonication treatment), sorption isotherms showed that OH-, COOH- and NH 2 -CNTs exhibited significantly different sorption affinity for pyrene. Sonication greatly increased both the sorption affinity and the maximum capacity of all types of functionalized CNTs, to an extent that overwhelmed the differences initially observed (increase of up to 1.5 orders of magnitude lead to log K d values close to 9 L/kg). Results demonstrate that a significant proportion of the CNT surface was unavailable to pyrene prior to sonication. The presence of humic acids enhanced dispersion but decreased sorption, especially when combined with sonication. Sorption affinity, however, remained very high in all cases (log K d > 7.5 L/kg), suggesting that CNTs can act as strong sorbents under a wide range of conditions. [ABSTRACT FROM AUTHOR]
- Published
- 2014
- Full Text
- View/download PDF
42. Nanopesticides: Guiding Principles for Regulatory Evaluation of Environmental Risks.
- Author
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Rai, S. Kookana, Boxall, Alistair B. A., Reeves, Philip T., Ashauer, Roman, Beulk, Sabine, Chaudhry, Qasim, Cornelis, Geert, Fernande, Teresa F., Gan, Jay, Kah, Melanie, Lynch, Iseult, Ranville, James, Sinclair, Chris, Spurgeon, David, Tiede, Karen, and Van den Brink, Paul J.
- Published
- 2014
- Full Text
- View/download PDF
43. Nanopesticide research: Current trends and future priorities.
- Author
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Kah, Melanie and Hofmann, Thilo
- Subjects
- *
PESTICIDES , *PLANT protection , *NANOTECHNOLOGY , *TITANIUM dioxide , *RISK assessment , *ENVIRONMENTAL impact analysis - Abstract
Abstract: The rapid developments in nanopesticide research over the last two years have motivated a number of international organizations to consider potential issues relating to the use of nanotechnology for crop protection. This analysis of the latest research trends provides a useful basis for identifying research gaps and future priorities. Polymer-based formulations have received the greatest attention over the last two years, followed by formulations containing inorganic nanoparticles (e.g., silica, titanium dioxide) and nanoemulsions. Investigations have addressed the lack of information on the efficacy of nanopesticides and a number of products have been demonstrated to have greater efficacy than their commercial counterparts. However, the mechanisms involved remain largely unknown and further research is required before any generalizations can be made. There is now increased motivation to develop nanopesticides that are less harmful to the environment than conventional formulations, and future investigations will need to assess whether any promising products developed are able to compete with existing formulations, in terms of both cost and performance. Investigations into the environmental fate of nanopesticides remain scarce, and the current state of knowledge does not appear to be sufficient for a reliable assessment to be made of their associated benefits and risks. A great deal of research will therefore be required over the coming years, and will need to include (i) the development of experimental protocols to generate reliable fate properties, (ii) investigations into the bioavailability and durability of nanopesticides, and (iii) evaluation of current environmental risk assessment approaches, and their refinement where appropriate. [Copyright &y& Elsevier]
- Published
- 2014
- Full Text
- View/download PDF
44. How Redox Conditions and Irradiation Affect Sorption of PAHs by Dispersed Fullerenes (nC60).
- Author
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Hüffer, Thorsten, Kah, Melanie, Hofmann, Thilo, and Schmidt, Torsten C.
- Subjects
- *
SORPTION , *POLYCYCLIC aromatic hydrocarbons & the environment , *FULLERENES , *CARBON compound analysis , *DISPERSION (Chemistry) , *IRRADIATION , *OXIDATION-reduction reaction , *ISOTHERMAL processes , *HYDROPHOBIC organic pollutants - Abstract
Surface properties, dispersion state, and sorption behavior of carbon-based nanomaterials will change after being released into the environment. To study these processes, five different scenarios were considered to probe the impact of changes in surface properties of dispersed fullerenes (nC60) on their sorption potential due to irradiation and presence of oxygen. Sorption isotherms of pyrene by nC60 were determined at environmentally relevant concentrations applying a passive sampling method. Isotherms of all dispersion scenarios were best fit with the Dubinin-Ashthakov model. Sorption was strongest for nC60 kept under anoxic condition. Both the presence of oxygen and irradiation significantly decreased the sorption capacity of nC60, while commercially available polyhydroxy fullerenes had the smallest sorption. In addition, competition for sorption sites was never observed in multiple sorbate experiments with four polycyclic aromatic hydrocarbons at small concentration. A strong relationship between sorption coefficients and hydrophobic properties of sorbates suggests that hydrophobic interactions are of major importance. The results emphasize that aging of released fullerenes results in a reduced strength of interactions with nonpolar compounds and, thus, reduces the impact on the environmental transport of hydrophobic pollutants. [ABSTRACT FROM AUTHOR]
- Published
- 2013
- Full Text
- View/download PDF
45. Potential for Effects of Land Contamination on Human Health. 2. The Case of Waste Disposal Sites.
- Author
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Kah, Melanie, Levy, Len, and Brown, Colin
- Subjects
- *
WASTE disposal in the ground , *WASTE disposal sites , *HAZARDOUS wastes , *INDUSTRIAL pollution , *WASTE products - Abstract
This review of the epidemiological literature shows that evidence for negative impacts of land contaminated by waste disposal on human health is limited. However, the potential for health impacts cannot be dismissed. The link between residence close to hazardous waste disposal sites and heightened levels of stress and anxiety is relatively well established. However, studies on self-reported outcomes generally suffer from interpretational problems, as subjective symptoms may be due to increased perception and recall. Several recent multiple-site studies support a plausible linkage between residence near waste disposal sites and reproductive effects (including congenital anomalies and low birth weight). There is some conflict in the literature investigating links between land contamination and cancers; the evidence for and against a link is equally balanced and is insufficient to make causal inferences. These are difficult to establish because of lack of data on individual exposures, and other socioeconomic and lifestyle factors that may confound a relationship with area of residence. There is no consistently occurring risk for any specific tumor across multiple studies on sites expected to contain similar contaminants. Further insights on health effects of land contamination are likely to be gained from studies that consider exposure pathways and biomarkers of exposure and effect, similar to those deployed with some success in investigating impacts of cadmium on human health. [ABSTRACT FROM AUTHOR]
- Published
- 2012
- Full Text
- View/download PDF
46. Dispersion State and Humic Acids Concentration-Dependent Sorption of Pyrene to Carbon Nanotubes.
- Author
-
Xiaoran Zhang, Kah, Melanie, Jonker, Michiel T. O., and Hofmann, Thilo
- Subjects
- *
SONICATION , *HUMIC acid , *DISPERSION (Chemistry) , *CARBON nanotubes , *SORPTION , *PYRENE - Abstract
Sonication and humic acids (HA) are known to disperse carbon nanotube (CNT) suspensions, but potential effects on sorption of chemicals to CNTs remain poorly understood. We applied a passive sampling method to investigate the influence of dispersion/aggregation on sorption of pyrene to CNTs. Sonication broke down CNT aggregates and increased pyrene sorption affinity by up to 1.39 orders of magnitude. Sorption surfaces newly exposed by sonication remained available to pyrene even after reaggregation occurred, suggesting an irreversible effect of sonication. The presence of HA decreased sorption of pyrene to CNTs, but at the highest HA concentration investigated (200 mg/L), sorption affinity was still 1.90 orders of magnitude larger than sorption of pyrene to HA alone. Specific interactions between pyrene and CNTs were thus still taking place, in spite of the presence of a HA coating on the CNTs' surface. A greater suppression of sorption by CNTs occurred when the HA addition was combined with a sonication pretreatment. Sorption isotherm fitting indicated that the maximum sorption capacity, sorption affinity, and heterogeneity of the CNT surface were all affected by sonication and the presence of HA at a concentration as low as 1 mg/L. The present results contribute to an improved understanding of the sorption behavior of CNTs in both natural and wastewater systems. [ABSTRACT FROM AUTHOR]
- Published
- 2012
- Full Text
- View/download PDF
47. Potential for Effects of Land Contamination on Human Health. 1. The Case of Cadmium.
- Author
-
Kah, Melanie, Levy, Len, and Brown, Colin
- Subjects
- *
BIOMARKERS , *EXOCRINE secretions , *BLOOD circulation disorders , *CADMIUM , *HEAVY metals , *INDUSTRIAL contamination - Abstract
A review of the epidemiological literature on the potential effects of land contamination shows that the largest body of contaminant-specific research relates to cadmium (Cd). First, a brief outline of the key issues related to the study of health impact of land contamination is presented. The recent literature is then reviewed for evidence of associations and possible causal relationships between exposure to Cd from land contamination and health impact. A large number of studies focusing on Cd arise because of the ready availability of biomarkers of exposure and effect and the demonstrated link between soil Cd and itai-itai disease (severe renal and bone disorders) via dietary exposure in Japan and China. Where dietary differences yield lower exposures, links have been established between Cd in soil and biomarkers of renal or bone dysfunctions, but not to health impacts per se. Potential effects of Cd exposure were also investigated for other health outcomes, including hypertension, cancer incidence, preterm delivery, and semen parameters. In contrast to renal and bone disorders, results are generally inconsistent and require further lines of evidence. Residence in locations with elevated concentrations of Cd in soil is a poor surrogate for exposure, and there are examples where residents in locations with elevated concentrations of Cd in soil did not appear to suffer serious health consequences. [ABSTRACT FROM AUTHOR]
- Published
- 2012
- Full Text
- View/download PDF
48. Measuring and Modeling Adsorption of PAHs to Carbon Nanotubes Over a Six Order of Magnitude Wide Concentration Range.
- Author
-
Kah, Melanie, Xiaoran Zhang, Jonker, Michiel T. O., and Hofmann, Thilo
- Subjects
- *
ADSORPTION (Chemistry) , *POLYCYCLIC aromatic hydrocarbons , *CARBON nanotubes , *POLYOXYMETHYLENE , *RESEARCH methodology , *SAMPLING (Process) - Abstract
Understanding the interactions between organic contaminants and carbon nanomaterials is essential for evaluating the materials' potential environmental impact and their application as sorbent. Although a great deal of work has been published in the past years, data are still limited in terms of compounds, concentrations, and conditions investigated. We applied a passive sampling method employing polyoxymethylene (POM-SPE) to gain a better understanding of the interactions between polycyclic aromatic hydrocarbons (PAHs) and multiwalled carbon nanotubes (CNTs) over a 6 orders of magnitude wide concentration range. In the low-concentration range (pg-ng L-1), sorption of phenanthrene and pyrene was linear on a nonlogarithmic scale. Here, sorption could thus be described using a single sorption coefficient. Isotherm fits over the entire concentration range showed that (i) monolayer sorption models described the data very well, and (ii) the CNTs sorption capacity was directly related to their surface area. Sorption coefficients for 13 PAHs (11 of which have not been reported to date) were also measured at environmentally relevant low concentrations. No competition seemed to occur in the low-concentration range and sorption affinity was directly related to the solubility of the subcooled liquid of the compounds. [ABSTRACT FROM AUTHOR]
- Published
- 2011
- Full Text
- View/download PDF
49. Log D: Lipophilicity for ionisable compounds
- Author
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Kah, Melanie and Brown, Colin D.
- Subjects
- *
PARTITION coefficient (Chemistry) , *PESTICIDES , *HYDROGEN-ion concentration , *IONIC solutions , *CELL polarity , *SOLUTION (Chemistry) , *AGRICULTURAL chemicals , *HYDROPHILE-lipophile balance - Abstract
The octanol/water partition coefficient (Kow) for organic compounds is widely used in predictive environmental studies. A significant proportion of contaminants of surface and ground water are ionisable (e.g. many pesticides, pharmaceuticals, metabolites). Such compounds may be partially ionised dependent on the pH. Since the neutral and ionic species exhibit different polarities, the Kow value of ionisable pesticides is pH dependent. It is therefore essential to determine Kow values over the full range of pH that occurs in the environment in order to get appropriate predictors. Numerous methods are available to measure lipophilicity but only a few are appropriate for ionisable pesticides (e.g. pH metric and filter probe methods). Parameters such as pH and ionic strength need to be carefully controlled when working with ionisable compounds. Variation of these factors probably explains why literature can yield Kow values that differ by more than one order of magnitude for some compounds. In this article, Kow values obtained for six acidic pesticides with three different methods are compared as well (data from the literature, measured by pH metric method and calculated with five computer programs). The values used in predictive regression equations needs to be either measured with a suitable method or selected from the literature with great care. [Copyright &y& Elsevier]
- Published
- 2008
- Full Text
- View/download PDF
50. Adsorption and degradation of four acidic herbicides in soils from southern Spain.
- Author
-
Villaverde, Jaime, Kah, Melanie, and Brown, Colin D
- Subjects
PESTICIDE pollution ,ADSORPTION (Chemistry) ,CARBOXYLIC acids ,SULFONYLUREAS ,ANALYSIS of clay ,ORGANIC compounds - Abstract
BACKGROUND: Pesticide degradation and adsorption in soils are key processes determining whether pesticide use will have any impact on environmental quality. Pesticide degradation in soil generally results in a reduction in toxicity, but some pesticides have breakdown products that are more toxic than the parent compound. Adsorption to soil particles ensures that herbicide is retained in the place where its biological activity is expressed and also determines potential for transportation away from the site of action. Degradation and adsorption are complex processes, and shortcomings in understanding them still restrict the ability to predict the fate and behaviour of ionisable pesticides. This paper reports the sorption and degradation behaviour of four acidic pesticides in five soils from southern Spain. Results are used to investigate the influence of soil and pesticide properties on adsorption and degradation as well as the potential link between the two processes. RESULTS: Adsorption and degradation of four acidic pesticides were measured in four soils from Spain characterised by small organic matter (OM) contents (0.3–1.0%) and varying clay contents (3–66%). In general, sorption increased in the order dicamba < metsulfuron-methyl < 2,4-D < flupyrsulfuron-methyl-sodium. Both OMand clay content were found to be important in determining adsorption, but relative differences in clay content between soils were much larger than those in OM content, and therefore clay content was the main property determining the extent of herbicide adsorption for these soils. pH was negatively correlated with adsorption for all compounds apart from metsulfuron-methyl. A clear positive correlation was observed for degradation rate with clay and OM content (P < 0.01), and a negative correlation was observed with pH (P < 0.01). The exception was metsulfuron-methyl, for which degradation was found to be significantly correlated only with soil bioactivity (P < 0.05). CONCLUSIONS: Both OM and clay content were found to be important in determining adsorption, but relative differences in clay content between soils were much larger than those inOMcontent, and therefore clay content was themain property determining the extent of herbicide adsorption for soils of this type. pHwas negatively correlated with adsorption for all compounds apart from etsulfuron-methyl. The contrasting behaviour shown for these four acidic pesticides indicates that chemical degradation in soil is more difficult to predict than adsorption. Most of the variables measured were interrelated, and different behaviours were observed even for compounds from the same chemical class and with similar structures. [ABSTRACT FROM AUTHOR]
- Published
- 2008
- Full Text
- View/download PDF
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