Modelling environmental impacts of agriculture, focusing on oil palm

Cultivation of crops affects the environment via flows of energy and materials. Impacts are felt in the atmosphere, hydrosphere, surrounding terrestrial ecosystems and the field itself. Models are useful tools for improving our understanding of the processes and predicting how they might be affected by changes in management. Current models range from simple indicators of risk or impact, based on empirical relationships, to dynamic process-based models. Increasingly complex and comprehensive models with increasing spatial and temporal resolution and extent are being developed, mostly by coupling diverse sub-models. This chapter reviews the range of models developed for oil palm systems, and discusses how other existing models might be adapted for oil palm

Sorption behaviour of per- and polyfluoroalkyl substances (PFASs) in tropical soils

The sorption behaviour of three perfluoroalkyl substances (PFASs), namely perfluorooctane sulfonic acid (PFOS), perfluorooctanoic acid (PFOA) and perfluorohexane sulfonic acid (PFHxS), was determined on 28 tropical soils. Tropical soils are often highly weathered, richer in sesquioxides than temperate soils and may contain variable charge minerals. There are little data on sorption of PFASs in tropical soils. The highest Kd values were found for PFOS with mean values ranging from 0 to 31.6 L/kg. The Kd values for PFOA and PFHxS ranged from 0 to 4.9 L/kg and from 0 to 5.6 L/kg, respectively. While these values are in the range of literature sorption data, the average Kd values for PFOS and PFOA from the literature were 3.7 times and 3.6 times higher, respectively, than those measured in this study. Stepwise regression analysis did explain some of the variance, but with different explanatory variables for the different PFASs. The main soil properties explaining sorption for PFOS and PFOA were oxalate-extractable Al and pH, and for PFHxS was pH

The role of surface charge and pH changes in tropical soils on sorption behaviour of per- and polyfluoroalkyl substances (PFASs)

Crown Copyright © 2019 Published by Elsevier B.V. This manuscript version is made available under the CC-BY-NC-ND 4.0 license: http://creativecommons.org/licenses/by-nc-nd/4.0/ This author accepted manuscript is made available following 24 month embargo from date of publication (April 2019) in accordance with the publisher’s archiving policyThis study investigated the effect of surface charge on the sorption of perfluorooctane sulfonic acid (PFOS), perfluorooctanoic acid (PFOA) and perfluorohexane sulfonic acid (PFHxS) onto 7 tropical soils as a function of pH. The net surface charge became less negative with decreasing pH (from 7.5 to 3.5) in all soils. The rate of change in net surface charge varied from −0.6 to −2.8 (cmol/kg)/pH unit. The effect on sorption behaviour of PFASs was variable among soils. For two soils, the average sorption increased 54- and 45-fold for PFOS, 33- and 9-fold for PFOA, and 39- and 400-fold for PFHxS, across the pH range 7.5 to 3.5. Sorption in another sandier soil showed negligible change with decreasing pH. Sorption in the other soils did not change significantly until the pH decreased to approximately 5.5. The soils with high contents of sesquioxides (Fe and Al oxides) showed the most marked increase in sorption with decreasing pH. This study demonstrated that in addition to hydrophobic interactions with OC and other processes, electrostatic interactions are also important in the sorption process for these chemicals in soils. In acidic, variably charged tropical soils there is the possibility that any PFOS, PFOA or PFHxS sorbed to the soils may become desorbed if management practices (e.g. liming) raised soil pH

Comprehensive framework for human health risk assessment of nanopesticides

Nanopesticides are not only in an advanced state of research and development but have started to appear on the market. Industry and regulatory agencies need a consolidated and comprehensive framework and guidance for human health risk assessments. In this perspective we develop such a comprehensive framework by exploring two case studies from relevant product types: an active ingredient delivered with a nanocarrier system, and a nanoparticle as an active ingredient. For a nanocarrier system, three entities are tracked during the assessment: the nanocarrier–active ingredient complex, the empty nanocarrier remaining after the complete release of the active ingredient, and the released active ingredient. For the nanoparticle of pure active ingredient, only two entities are relevant: the nanoparticle and the released ions. We suggest important adaptations of the existing pesticide framework to determine the relevant nanopesticide entities and their concentrations for toxicity testing. Depending on the nature of the nanopesticides, additional data requirements, such as those pertaining to durability in biological media and potential for crossing biological barriers, have also been identified. Overall, our framework suggests a tiered approach for human health risk assessment, which is applicable for a range of nanopesticide products to support regulators and industry in making informed decisions on nanopesticide submissions. Brief summaries of suitable methods including references to existing standards (if available) have been included together with an analysis of current knowledge gaps. Our study is an important step towards a harmonized approach accepted by regulatory agencies for assessing nanopesticides

Developing Global Leaders for Research, Regulation, and Stewardship of Crop Protection Chemistry in the 21st Century

To provide sufficient food and fiber to the increasing global population, the technologies associated with crop protection are growing ever more sophisticated but, at the same time, societal expectations for the safe use of crop protection chemistry tools are also increasing. The goal of this perspective is to highlight the key issues that face future leaders in crop protection, based on presentations made during a symposium titled “Developing Global Leaders for Research, Regulation and Stewardship of Crop Protection Chemistry in the 21st Century”, held in conjunction with the IUPAC 13th International Congress of Pesticide Chemistry in San Francisco, CA, USA, during August 2014. The presentations highlighted the fact that leaders in crop protection must have a good basic scientific training and understand new and evolving technologies, are aware of the needs of both developed and developing countries, and have good communication skills. Concern is expressed over the apparent lack of resources to meet these needs, and ideas are put forward to remedy these deficiencies.Keywords: sustainable agriculture, developing regions, training leaders, smart systems, stewardship, women in agriculture, crop protection, universities, nanopesticides, communications, GM crop

Fate and Uptake of Pharmaceuticals in Soil–Plant Systems

Pharmaceuticals have been detected in the soil environment where there is the potential for uptake into crops. This study explored the fate and uptake of pharmaceuticals (carbamazepine, diclofenac, fluoxetine, propranolol, sulfamethazine) and a personal care product (triclosan) in soil–plant systems using radish (Raphanus sativus) and ryegrass (Lolium perenne). Five of the six chemicals were detected in plant tissue. Carbamazepine was taken up to the greatest extent in both the radish (52 μg/g) and ryegrass (33 μg/g), whereas sulfamethazine uptake was below the limit of quantitation (LOQ) (<0.01 μg/g). In the soil, concentrations of diclofenac and sulfamethazine dropped below the LOQ after 7 days. However, all pharmaceuticals were still detectable in the pore water at the end of the experiment. The results demonstrate the ability of plant species to accumulate pharmaceuticals from soils with uptake apparently specific to both plant species and chemical. Results can be partly explained by the hydrophobicity and extent of ionization of each chemical in the soil