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Understanding possible causes of exceeding dioxin levels in palm oil by-products: An explorative study
No full textThe Rapid Alert System for Food and Feed (period 1999–2014) reported exceeding levels of dioxins (polychlorinated dibenzo-p-dioxinsand dibenzofurans (PCDD/Fs)) in palm oil by-products, such as palm fatty acid distillate (PFAD) and hydrogenated palm fatty acid distillate (HPFAD), but not in crude and refined palm oil. The aim of the present study was to gain insight into the occurrence and congener profiles of dioxin contamination during industrial processing of crude palm oil into refined oil and its by-products PFAD and HPFAD via analysis of individual congener concentrations. In total, 1217 samples from an industrial process were collected at four different points, crude palm oil at delivery (N = 202), fresh bleaching earth before bleaching (N = 84), PFAD after deodorising palm oil (N = 553), and HPFAD after hydrogenation of PFAD (N = 378). Congener profiles were analysed by GC-HRMS, and toxic equivalent (TEQ) levels were calculated using toxic equivalence factors (TEF) of WHO2005 to assess non-compliance to legal limits. All dioxin levels in crude palm oil samples were far below the action limit. All dioxin levels in fresh bleaching earth were in compliance with the maximum level. For the by-product samples, such as PFAD, 0.6% exceeded the action level, but all were below the maximum level (ML). However, for 1.3% of the HPFAD samples, the TEQ level exceeded the ML. In-depth analysis of the congener profiles revealed that after the hydrogenation step, the concentration of the lower chlorinated congeners in the HPFAD samples was higher than in the PFAD samples. The hydrogen atoms possibly replaced the chlorine atoms during hydrogenation. As these lower chlorinated congeners have a higher TEF, when they are regulated, their contribution to the calculated TEQ is higher, which resulted in some HPFAD samples exceeding the legal limit. Further research is needed to obtain insight into the changes in PCDD/F congener profiles during the hydrogenation of palm oil products.</p
Sulfur controlled cadmium dissolution in pore water of cadmium-contaminated soil as affected by DOC under waterlogging
No full textCadmium (Cd) precipitation and dissolution in pore water is associated with dissolved organic carbon (DOC)-induced reduction-oxidation of sulfur (S) under waterlogging and is vital for controlling the bioavailability in paddy soil. A 120-day soil incubation experiment, including application of sulfur (S, 30 mg kg−1) and wheat straw (W, 1.0%) alone or in combination (W + S) into Cd-contaminated paddy soil under waterlogging, was conducted to investigate the dynamic of dissolved Cd and its relationship with DOC, S2−, Fe2+, pH, Eh and pe + pH in soil pore water. The results showed that the lowest dissolved Cd concentration was observed in the W + S-treated soil pore water among all treatments when the soil Eh remained at lower values during the period of 15–60 days of incubation, which could be attributed to CdS precipitation and/or co-precipitation of Cd absorbed by FeS2 because of the reduction in sulfur. The application of S resulted in a Cd rebound in the pore water irrespective of W addition when the Eh began to increase from its lowest values during the period of 45–75 days of incubation, and SOB genera were observed in the S added soil. This could be attributed to re-dissolution of the precipitated Cd in soils under the SOB-driven oxidation of sulfide such as CdS and FeS2. In conclusion, DOC-driven reduction-oxidation of sulfur controls Cd dissolution in the pore water of Cd-contaminated paddy soil under waterlogging conditions. Further studies are required to investigate the interaction of sulfur and SOM-induced DOC on Cd bioavailability in rice-planted paddy soils.</p
Benzotriazole removal mechanisms in pilot-scale constructed wetlands treating cooling tower water
Full text linkThe reuse of discharged cooling tower water (CTW) in the cooling tower itself could reduce fresh water intake and help mitigating fresh water scarcity problems. However, this requires desalination prior to its reuse, and hindering fractions, such as conditioning chemicals, should be removed before desalination to obtain a higher desalination efficiency. Constructed wetlands (CWs) can provide such a pre-treatment. In this study, the mechanisms underlying the removal of conditioning chemical benzotriazole (BTA) in CWs was studied using an innovative approach of differently designed pilot–scale CWs combined with batch removal experiments with substrate from these CWs. By performing these combined experiments, it was possible to determine the optimal CW design for BTA removal and the most relevant BTA removal processes in CWs. Adsorption yielded the highest contribution, and the difference in removal between different CW types was linked to their capability to aerobically biodegrade BTA. This knowledge on the main removal mechanisms for BTA allows for a CW design tailored for BTA removal. In addition, the outcomes of this research show that performing batch experiments with CW substrate allows one to determine the relevant removal mechanisms for a given compound which results in a better understanding of CW removal processes.</p
Foreseeing the future of mutualistic communities beyond collapse
No full textChanging conditions may lead to sudden shifts in the state of ecosystems when critical thresholds are passed. Some well‐studied drivers of such transitions lead to predictable outcomes such as a turbid lake or a degraded landscape. Many ecosystems are, however, complex systems of many interacting species. While detecting upcoming transitions in such systems is challenging, predicting what comes after a critical transition is terra incognita altogether. The problem is that complex ecosystems may shift to many different, alternative states. Whether an impending transition has minor, positive or catastrophic effects is thus unclear. Some systems may, however, behave more predictably than others. The dynamics of mutualistic communities can be expected to be relatively simple, because delayed negative feedbacks leading to oscillatory or other complex dynamics are weak. Here, we address the question of whether this relative simplicity allows us to foresee a community's future state. As a case study, we use a model of a bipartite mutualistic network and show that a network's post‐transition state is indicated by the way in which a system recovers from minor disturbances. Similar results obtained with a unipartite model of facilitation suggest that our results are of relevance to a wide range of mutualistic systems
Overcoming the dependent variable problem in studying food policy
No full textThe development of a comparative food policy research agenda has been hampered by the dependent variable problem of how to delineate the policy field. Through a concise literature review, we show that the existing literature has conceptualised food policy as policy outputs, institutional orders, or discursive constructs. Focusing on the policy outputs, we define food policy as a set of policy outputs adopted to address one or more food system activities (production, processing and packaging, distribution and retailing, and consumption) with the explicit aim of affecting food system outcomes in a desired direction. The paper develops a heuristic encompassing four dimensions along which food policy outputs may differ: (i) policy scope, (ii) targeting of policy efforts, (iii) type of policy instruments applied and how these are calibrated, and (iv) integration of the various components of the policy complex. These four dimensions can be applied to characterise individual food policies and compare across countries and time. Comparing and tracking the development of food policy along these dimensions would allow for addressing follow-up questions about impacts and what explains policy change
Common pool resources with support
No full textWe examine the role of support for coalition stability in common pool resource games such as fisheries games. Some players may not want to join a coalition that jointly manages a resource. Still, because they benefit from spillovers, they may want to support the coalition with a transfer payment to set incentives for others to join. We find that the impact of support on equilibria of this game is limited to games with three or five players. Recommendations for Resource Managers. Coalitions may be able to effectively manage common pool resources such as fisheries but such coalitions are often not stable due to free-rider incentives. We explore the impact of a transfer scheme that can improve this coalition stability which would lead to larger and more effective coalitions. Our results show that this new transfer scheme works only for cases where the number of players is small.</p
Back to the future: rethinking socioecological systems underlying high nature value farmlands
No full textFarmlands are currently among the dominant uses of the land. When managed under low-input farming systems, farmlands are associated with diverse cultural and natural heritages around the world. Known in Europe as high nature value (HNV) farmlands, these agricultural landscapes and their associated farming systems evolved as tightly coupled socioecological systems, and are essential to biodiversity conservation and the delivery of ecosystem services to society. However, HNV farmlands are vulnerable to socioeconomic changes that lead to either agricultural intensification or land abandonment. We present a range of plausible future scenarios for HNV farmlands, and discuss the related management options and expected socioecological outcomes for each scenario. We then provide recommendations for policy, practice, and research on how to best ensure the socioecological viability of HNV farming systems in the future.</p
Predicting intraparticle diffusivity as function of stationary phase characteristics in preparative chromatography
No full textDiffusion inside pores is the rate limiting step in many preparative chromatographic separations and a key parameter for process design in weak interaction aqueous chromatographic separations employed in food and bio processing. This work aims at relating diffusion inside porous networks to properties of stationary phase and of diffusing molecules. Intraparticle diffusivities were determined for eight small molecules in nine different stationary phases made from three different backbone materials. Measured intraparticle diffusivities were compared to the predictive capability of the correlation by Mackie and Meares and the parallel pore model. All stationary phases were analyzed for their porosity, apparent pore size distribution and tortuosity, which are input parameters for the models. The parallel pore model provides understanding of the occurring phenomena, but the input parameters were difficult to determine experimentally. The model predictions of intraparticle diffusion were of limited accuracy. We show that prediction can be improved when combining the model of Mackie and Meares with the fraction of accessible pore volume. The accessible pore volume fraction can be determined from inverse size exclusion chromatographic measurements. Future work should further challenge the improved model, specifically widening the applicability to greater accessible pore fractions (> 0.7) with corresponding higher intraparticle diffusivities (Dp/Dm > 0.2). A database of intraparticle diffusion and stationary phase pore property measurements is supplied, to contribute to general understanding of the relationship between intraparticle diffusion and pore properties.</p
Development of a refuge-kairomone device for monitoring and control of the vine weevil, Otiorhynchus sulcatus, by lure-and-kill and lure-and-infect
No full textRoot weevils in the genus Otiorhynchus are an important pest in the nursery and small fruit production worldwide. The night-activity of the adult weevils obstruct timely monitoring and oviposition often starts before effective control measures are taken. The primary objective of this research goal was to develop an effective trap for monitoring that can be used in conjunction with the kairomone (Z)-2-pentenol and an effective means to kill the insects that enter the trap. A novel ruffle refuge trap (WeevilGrip) caught on average 4 to 5 times more weevils than a grooved board refuge in a field trial. Addition of the kairomone to the WeevilGrip further increased catches 52%. Linseed oil increased mortality to 59% and addition of Botanigard (ai Beauveria bassiana, strain GHA, Certis, BotaniGard WP 10–25%) increased mortality to 79%. The lure-refuge device consists of a flexible ruffle that can be wrapped around trees or placed on the soil within ground covers. This flexible shape maximizes contact with weevils compared to other available weevil trap designs. The WeevilGrip is an improved monitoring tool to support growers in integrated control strategies.</p
Interfacial rheology and relaxation behavior of adsorption layers of the triterpenoid saponin Escin
No full textHypothesis: Escin, a monodesmosidic triterpenoid saponin, was shown previously to form viscoelastic interfaces with a very high dilatational and surface shear storage modulus. This is expected to be due to the arrangement of Escin into 2D disordered soft viscoelastic solid interfacial structures, which results in turn in a distribution of relaxation times. Experiments: The responses to dilatational and surface shear deformations of Escin-stabilized air-water interfaces were studied, both in the linear viscoelastic (LVE) and non-linear (NLVE) regime. Step relaxation and amplitude sweeps were performed in dilatation experiments. For surface shear, amplitude sweeps and creep recovery experiments were performed. Findings: Escin stabilized-interfaces displayed a highly non-linear behavior in dilatation as seen in the Lissajous plots. In large oscillatory shear the Lissajous curves had a rhomboidal shape, indicating intracycle yielding and recovery, typical of glassy systems. The relaxation of the interface showed stretched exponential behavior, with stretched exponents typical of disordered solids with dynamic heterogeneity. The use of surface rheological measurements beyond the commonly measured LVE regime clearly has provided new insights into the behavior of these interfaces and their microstructure. These results highlight the need to reconsider other complex interfaces as disordered solids and not as 2D homogenous viscoelastic fluids.</p