0000000000070898
AUTHOR
Amilcare Porporato
The role of hydrology on enhanced weathering for carbon sequestration in soils
Natural climate solutions are attracting considerable research effort with the aim of reducing greenhouse gas emissions or sequestering carbon within the oceans or terrestrial environments. In this context, enhanced weathering can be a powerful means of increasing the natural weathering reaction rates, by adding some highly reactive minerals to the soil. The present study evaluates the effects of hydrologic fluctuations on Forsterite dissolution, a silicate mineral also known as Mg-olivine. This mineral is available in many parts of the world and its reaction rates with CO2 are much higher than those of other minerals. Toward this goal, we developed a mathematical model coupling biogeochemi…
Nano- to Global-Scale Uncertainties in Terrestrial Enhanced Weathering.
Enhanced weathering (EW) is one of the most promising negative emissions technologies urgently needed to limit global warming to at least below 2 °C, a goal recently reaffirmed at the UN Global Climate Change conference (i.e., COP26). EW relies on the accelerated dissolution of crushed silicate rocks applied to soils and is considered a sustainable solution requiring limited technology. While EW has a high theoretical potential of sequestering CO2, research is still needed to provide accurate estimates of carbon (C) sequestration when applying different silicate materials across distinct climates and major soil types in combination with a variety of plants. Here we elaborate on fundamental …
A cropland application of Enhanced Weathering in the Mediterranean area to face climate change and preserve natural resources
The goal of limiting the use of natural resources and combatting climate change has led to the improvement of agricultural techniques and the development of some Carbon Dioxide Removal (CDR) techniques, given their proficiency to sequester carbon from the atmospheric CO2 and to store it in more stable forms within oceans, plants, soil, or other terrestrial environments. Among them, Enhanced Weathering (EW) is regarded as one of the most promising. This consists of amending soils with silicate minerals, such as olivine, so as to speed up the weathering process that naturally occurs in soils. This work aims to couple a model for the resolution of the agro-hydrological balance in the active so…
Effects of precipitation seasonality, vegetation cycle, and irrigation on enhanced weathering
Enhanced Weathering (EW) is a promising strategy for carbon sequestration, but several open questions remain regarding the actual rates of dissolution in conditions of natural hydroclimatic variability in comparison to laboratory experiments. In this context, models play a pivotal role, as they allow exploring and predicting EW dynamics under different environmental conditions. Here a comprehensive hydro-biogeochemical model has been applied to four cropland case studies (i.e., Sicily and the Padan plain in Italy and California and Iowa in the USA) characterized by different rainfall seasonality, vegetation (i.e., wheat for Sicily and California and corn for Padan plain and Iowa), and soil …
Effects of precipitation seasonality, irrigation, vegetation cycle and soil type on enhanced weathering – modeling of cropland case studies across four sites
Enhanced weathering (EW) is a promising strategy for carbon sequestration, but several open questions remain regarding the actual rates of dissolution in conditions of natural hydroclimatic variability in comparison to laboratory experiments. In this context, models play a pivotal role, as they allow exploring and predicting EW dynamics under different environmental conditions. Here a comprehensive hydro-biogeochemical model has been applied to four cropland case studies (i.e., Sicily and the Padan plain in Italy and California and Iowa in the USA) characterized by different rainfall seasonality, vegetation (i.e., wheat for Sicily and California and corn for the Padan plain and Iowa), and s…
Olive yield as a function of soil moisture dynamics
This study introduces a water-driven crop model aiming to quantitatively link olive yield to climate and soil moisture dynamics using an ecohydrological approach. A mathematical model describing soil moisture, evapotranspiration and assimilation dynamics of olive orchards is developed here. The model is able to explicitly reproduce two different hydroclimatic phases in Mediterranean areas: the well-watered conditions in which evapotranspiration and assimilation assume their maximum values and the real conditions where the limitations induced by soil moisture availability are taken into account. Annual olive yield is obtained by integrating the carbon assimilation during the growing season, …
Transient soil-moisture dynamics and climate change in Mediterranean ecosystems
[1] Plants in Mediterranean ecosystems have developed different strategies to cope with transient soil-moisture dynamics induced by the markedly out of phase seasonal behavior of rainfall and temperature. Deep-rooted plants use the soil moisture stored in the wet winter (extensive users), while shallower rooted plants exploit both the wet season storage and the more sporadic growing season rainfall (intensive users). Using stochastic models of soil-moisture dynamics, we present an analytical and numerical description of the probabilistic structure of the soil-moisture storage at the beginning of the growing season in relation to the dynamics of the wet season and then study its evolution du…
THE ROLE OF HYDROLOGICAL PROCESSES ON ENHANCED WEATHERING FOR CARBON SEQUESTRATION IN AGRICULTURAL SOILS
With the aim to face climate change, some NCS (Natural Climate Solutions) are currently studied given their capability to sequester carbon from the atmospheric CO2, by means of some natural processes, and to store it within oceans, plants, soil, or other terrestrial environments. Among all the existing NCS, Enhanced Weathering (EW) acts in speeding up the chemical weathering that naturally occurs in soils. This is achieved by amending soils with crushed highly reactive silicate minerals, such as forsterite, better known as olivine. In general, EW reactions are faster at high temperature and soil water content and low soil pH, demonstrating that the most suitable places in the world to apply…
The Role of Hydrological Processes on Enhanced Weathering for Carbon Sequestration in Cropland Areas: An Application to Italy
Aiming at facing climate change, some CDR (Carbon Dioxide Removal) techniques are currently studied given their capability to sequester carbon from the atmospheric CO2 and to store it within oceans, plants, soil, or other terrestrial environments. Among them, Enhanced Weathering (EW), that acts in speeding up the chemical weathering naturally occurring in soils through the amendments of highly reactive silicate minerals, is referred to as one of the most promising. Hot and humid climates provide the best conditions for EW, since reactions are faster at high temperature, high soil water content and low soil pH. This study presents a dynamic mass balance model that explores ecohydrological, b…
The role of hydrology on enhanced weathering for carbon sequestration II. From hydroclimatic scenarios to carbon-sequestration efficiencies
Abstract Enhanced weathering (EW) scenarios are analyzed using the model presented in Cipolla et al. (2020). We explore the role of different hydroclimatic forcing on carbon-sequestration efficiencies. We also investigate whether increasing soil carbon content improves weathering conditions. We link olivine weathering rates to pH variations and quantify the suitability of hydroclimatic regimes to EW, based on rainfall intensity and frequency. The results show that the amount of CO 2 reacting with olivine and ending up in solution in the form of HCO 3 − and CO 3 2 − increases with mean annual precipitation (MAP) up to 2000 mm, but then tapers off for higher MAPs. On the contrary, the sequest…
Modelling nonlinear dynamics of Crassulacean acid metabolism productivity and water use for global predictions
Crassulacean acid metabolism (CAM) crops are important agricultural commodities in water-limited environments across the globe, yet modeling of CAM productivity lacks the sophistication of widely used C3 and C4 crop models, in part due to the complex responses of the CAM cycle to environmental conditions. This work builds on recent advances in CAM modeling to provide a framework for estimating CAM biomass yield and water use efficiency from basic principles. These advances, which integrate the CAM circadian rhythm with established models of carbon fixation, stomatal conductance, and the soil-plant-atmosphere continuum, are coupled to models of light attenuation, plant respiration, and bioma…
The effects of seasonal variability of precipitation and vegetation cycle on enhanced weathering for carbon sequestration
<p>Enhanced weathering (EW) is one of the most promising technologies for sequestering atmospheric carbon. It consists on accelerating the chemical weathering fluxes naturally occurring in soils, by means of the addition of silicate minerals (i.e., <em>forsterite</em>), used as amendments, to the soil. If crushed into micrometer-sized particles, these minerals are characterized by high dissolution rates, that may be further improved under high soil water content and low pH conditions. Before actually applying EW technique at the global scale for carbon sequestration, an in-depth characterization of weathering and carbon sequestration rates, under di…
The role of hydrological processes on enhanced weathering for carbon sequestration in soils in tropical areas
<p>To mitigate global warming, a noticeable research effort is being devoted to NCS (Natural Climate Solutions) as means to reduce greenhouse gas emissions or sequester carbon within the oceans or terrestrial environments by exploiting natural processes. Enhanced weathering<strong> </strong>is a NCS that aims to increase the weathering reaction rates of silicate minerals, by amending soils with crushed reactive minerals. Various studies have shown that this technique is favored by hot and humid climates (i.e., tropical ecosystems), since weathering reactions are mostly effective under high temperature and soil moisture. Despite olivine dissolution d…
The role of hydrology on enhanced weathering for carbon sequestration I. Modeling rock-dissolution reactions coupled to plant, soil moisture, and carbon dynamics
Abstract Enhanced Weathering (EW) resulting from soil amendment with highly reactive silicate minerals is regarded as one of the most effective techniques for carbon sequestration. While in laboratory conditions silicate minerals dissolution rates are well characterized, in field conditions the rate of the dissolution reaction is more difficult to predict, not least because it interacts with soil, plant, and hydrologic processes. Here we present a dynamic mass balance model connecting biogeochemical and ecohydrological dynamics to shed light on these intertwined processes involved in EW. We focus on the silicate mineral olivine, for its faster laboratory dissolution rate, and pay particular…