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Abstract We apply a systems framework for analyzing the overall sustainability impacts of interventions to a case of the rice‐wheat cropping system of Punjab (India), where agricultural practices lead to air pollution‐related health impacts, over‐exploitation of groundwater, over‐use of fertilizers and reduced local crop diversity. We use this case to quantify how varying degrees of change in interventions result in sustainability impacts using an inclusive wealth‐based approach. We show that either improving the existing cropping system or inducing fundamental changes in the cropping system, can lead to substantial and wide‐ranging sustainability benefits. We also show that interventions that improve human health show the largest quantitative benefit due to the assumed high marginal value of human life. Accurate localized estimates of marginal values of stocks are needed for estimating overall sustainability impacts. 

To simulate global mercury (Hg) dynamics in chemical transport models (CTMs), surface-atmosphere exchange of gaseous elemental mercury, Hg 0 , is often parameterized based on resistance-based dry deposition schemes coupled with a re-emission function, mainly from soils. Despite extensive use of this approach, direct evaluations of this implementation against field observations of net Hg 0 exchange are lacking. In this study, we evaluate an existing net exchange parameterization (referred to here as the base model) by comparing modeled fluxes of Hg 0 to fluxes measured in the field using micrometeorological techniques. Comparisons were performed in two terrestrial ecosystems: a grassland site in Switzerland and an Arctic tundra site in Alaska, U.S., each including summer and winter seasons. The base model included the dry deposition and soil re-emission parameterizations from Zhang et al. (2003) and the global CTM GEOS-Chem, respectively. Comparisons of modeled and measured Hg 0 fluxes showed large discrepancies, particularly in the summer months when the base model overestimated daytime net deposition by approximately 9 and 2 ng m −2 h −1 at the grassland and tundra sites, respectively. In addition, the base model was unable to capture a measured nighttime net Hg 0 deposition and wintertime deposition. We conducted a series of sensitivity analyses and recommend that Hg simulations using CTMs: (i) reduce stomatal uptake of Hg 0 over grassland and tundra in models by a factor 5–7; (ii) increase nighttime net Hg 0 deposition, e.g. , by increasing ground and cuticular uptake by reducing the respective resistance terms by factors of 3–4 and 2–4, respectively; and (iii) implement a new soil re-emission parameterization to produce larger daytime emissions and lower nighttime emissions. We also compared leaf Hg 0 uptake over the growing season estimated by the dry deposition model against foliar Hg measurements, which revealed good agreement with the measured leaf Hg concentrations after adjusting the base model as suggested above. We conclude that the use of resistance-based models combined with the new soil re-emission flux parameterization is able to reproduce observed diel and seasonal patterns of Hg 0 exchange in these ecosystems. This approach can be used to improve model parameterizations for other ecosystems if flux measurements become available.