Rice, fish, and the planet

Lansing, J. Stephen; Kremer, James N.

doi:10.1073/pnas.1117707109

Cited by 31 publications

(16 citation statements)

References 17 publications

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“…Elevated MeHg concentrations are of concern to resident and migrating waterfowl, which visit rice fields due to their high productivity and extent (Elphick et al, 2000). More importantly, in tropical rice paddies, which combine rice and fish cultivation (e.g., Lansing and Kremer, 2011), potential co-exposure of MeHg through rice and fish consumption may be another concern, and requires further research.…”

Section: The Influence Of Rice Cultivation Practices On Hg Cyclingmentioning

confidence: 99%

Rice methylmercury exposure and mitigation: A comprehensive review

Rothenberg

Windham‐Myers

Creswell

2014

Environmental Research

169

151

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Rice cultivation practices from field preparation to post-harvest transform rice paddies into hot spots for microbial mercury methylation, converting less-toxic inorganic mercury to more-toxic methylmercury, which is likely translocated to rice grain. This review includes 51 studies reporting rice total mercury and/or methylmercury concentrations, based on rice cultivated or purchased in 15 countries. Not surprisingly, both rice total mercury and methylmercury levels were significantly higher in polluted sites compared to non-polluted sites (Wilcoxon rank sum, p<0.001). However, rice percent methylmercury (of total mercury) did not differ statistically between polluted and non-polluted sites (Wilcoxon rank sum, p=0.35), suggesting comparable mercury methylation rates in paddy soil across these sites and/or similar accumulation of mercury species for these rice cultivars. Studies characterizing the effect of rice cultivation under more aerobic conditions were reviewed to determine the mitigation potential of this practice. Rice management practices utilizing alternating wetting and drying (instead of continuous flooding) caused soil methylmercury levels to spike, resulting in a strong methylmercury pulse after fields were dried and reflooded; however, it is uncertain whether this led to increased translocation of methylmercury from paddy soil to rice grain. Due to the potential health risks, it is advisable to investigate this issue further, and to develop separate water management strategies for mercury polluted and non-polluted sites, which minimize methylmercury exposure through rice ingestion.

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Section: The Influence Of Rice Cultivation Practices On Hg Cyclingmentioning

confidence: 99%

Rice methylmercury exposure and mitigation: A comprehensive review

Rothenberg

Windham‐Myers

Creswell

2014

Environmental Research

169

151

View full text Add to dashboard Cite

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“…Previous studies have indicated that vertebrates and fish cultivated in flooded rice paddies will accumulate MeHg to critical threshold levels within 30 days . In rice paddy fields that combine rice and fish cultivation, potential co-exposure of MeHg through rice and fish consumption should receive more attention Feng et al, 2008;Lansing and Kremer, 2011).…”

Section: Source and Mechanism For Hg Transformation In Paddy Fieldmentioning

confidence: 99%

Mercury methylation in paddy soil: source and distribution of mercury species at a Hg mining area, Guizhou Province, China

et al. 2016

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Abstract. Rice paddy plantation is the dominant agricultural land use throughout Asia. Rice paddy fields have been identified as important sites for methylmercury (MeHg) production in the terrestrial ecosystem and a primary pathway of MeHg exposure to humans in mercury (Hg) mining areas. We compared the source and distribution of Hg species in different compartments of the rice paddy during a complete ricegrowing season at two different typical Hg-contaminated mining sites in Guizhou province, China: an abandoned site with a high Hg concentration in soil but a low concentration in the atmosphere and a current-day artisanal site with a low concentration in soil but a high concentration in the atmosphere. Our results showed that the flux of new Hg to the ecosystem from irrigation and atmospheric deposition was insignificant relative to the pool of old Hg in soil; the dominant source of MeHg to paddy soil is in situ methylation of inorganic Hg (IHg). Elevated MeHg concentrations and the high proportion of Hg as MeHg in paddy water and the surface soil layer at the artisanal site demonstrated active Hg methylation at this site only. We propose that the in situ production of MeHg in paddy water and surface soil is dependent on elevated Hg in the atmosphere and the consequential deposition of new Hg into a low-pH anoxic geochemical system. The absence of depth-dependent variability in the MeHg concentration in soil cores collected from the abandoned Hg mining site, consistent with the low concentration of Hg in the atmosphere and high pH of the paddy water and irrigation water, suggested that net production of MeHg at this site was limited. We propose that the concentration of Hg in ambient air is an indicator for the risk of MeHg accumulation in paddy rice.

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“…In Bali, effective control of insect pests requires much larger fallow episodes extending over entire subaks or groups of subaks, orders of magnitude larger than the plots in this study. Settle et al (1996Settle et al ( : 1978Settle et al ( , 1982 conclude that the size of synchronously planted areas is important: in Java, pest control is effective in synchronous planting of 10 to 100 ha with short fallow periods but rather ineffective where areas are considerably largerthousands of hectares-and preceded by long fallow periods suggesting that in the latter system natural rice pest enemies build up too late to contain pest populations (Lansing and Kremer 2011). adjust their irrigation schedules in response to local conditions, solving the jigsaw puzzle for entire watersheds that may include dozens of weirs and local irrigation systems.…”

Section: The Role Of Water Temples In Pest Controlmentioning

confidence: 96%

The Functional Role of Balinese Water Temples: A Response to Critics

Lansing

Vet

2012

Hum Ecol

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In earlier publications we have proposed a model to explain the functional role of water temple networks in the agro-ecology of wet rice irrigation on the island of Bali. We argued that the key ecological effects of temple networks are best understood as emergent properties of a complex adaptive system. This argument implies that important aspects of the temple system are largely opaque from the perspective of conventional social science. We proposed that the Green Revolution created a real-world test of our model, by effectively removing the temple networks from their functional role in ecological management. The idea that water temple networks represent a hitherto-unknown kind of institution has been met with appropriate skepticism by other social scientists, who have run a fine-toothed comb through our evidence. Here we evaluate their critiques.

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Rice, fish, and the planet

Cited by 31 publications

References 17 publications

Rice methylmercury exposure and mitigation: A comprehensive review

Rice methylmercury exposure and mitigation: A comprehensive review

Mercury methylation in paddy soil: source and distribution of mercury species at a Hg mining area, Guizhou Province, China

The Functional Role of Balinese Water Temples: A Response to Critics

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