02019nas a2200157   4500008004100000245005200041210005200093300001100145490000800156520155500164100001901719700002301738700001701761700001601778856006701794       2019                        eng d00aEvolution of carbonate and karst critical zones0 aEvolution of carbonate and karst critical zones  a1192230 v5273 a<p>Carbonate terrains (CT) underlie one-fifth of terrestrial, ice-free land and are an important supply of potable water to the world&#39;s population, and yet processes endemic to CT critical zones (CZ) and responses of these processes to climatic and anthropogenic pressures are not well understood. Given the rapid dissolution rates and ability to generate well-developed networks of secondary porosity these landscapes can be highly sensitive to impacts from climate change (e.g., modifications of temperature, precipitation, sea level) and human disturbance (e.g., water withdrawal/diversions, changes in land use/land cover). This special issue includes 16 papers focused on CT-CZ processes and potential responses to climatic and human perturbations. Five major themes emerge from these papers, namely: (1) anthropogenic climate and land use changes alter CT-CZ weathering rate and diagenesis, (2) metal and carbon fluxes in CT-CZ will respond to increasing hydrologic variance caused by climate change, (3) endogenous and exogenous processes operating over short time periods (&lt;10,000 yrs) form landscape patterns in carbonate terrains, (4) rates of carbonate mineral dissolution depend on vadose zone and soil thickness, and (5) open systems may not always promote greater carbonate weathering rates in CT-CZ. These findings reflect the importance of carbonate minerals in Earth&#39;s CZ, both in terms of processes unique to carbonate minerals, as well as a predictor of future responses to anthropogenic and environmental changes.</p>1 aSullivan, P.L.1 aMacpherson, G., L.1 aMartin, J.B.1 aPrice, R.M.  uhttps://linkinghub.elsevier.com/retrieve/pii/S000925411930318301419nas a2200181   4500008004100000245006500041210006500106300001200171490000800183520086800191100001701059700002301076700001901099700001701118700001901135700001601154856006701170       2018                        eng d00aLarge and active CO 2 uptake by coupled carbonate weathering0 aLarge and active CO 2 uptake by coupled carbonate weathering  a42 - 490 v1823 a<p>Carbonate mineral weathering coupled with aquatic photosynthesis on the continents, herein termed coupled carbonate weathering (CCW), represents a current atmospheric CO2 sink of about 0.5 Pg C/a. Because silicate mineral weathering has been considered the primary geological CO2 sink, CCW&#39;s role in the present carbon cycle has been neglected. However, CCW may be helping to offset anthropogenic atmospheric CO2 increases as carbonate minerals weather more rapidly than silicates. Here we provide an overview of atmospheric CO2 uptake by CCW and its impact on global carbon cycling. This overview shows that CCW is linked to climate and land-use change through changes in the water cycle and water-born carbon fluxes. Projections of future changes in carbon cycling should therefore include CCW as linked to the global water cycle and land-use change.</p>1 aLiu, Zaihua.1 aMacpherson, G., L.1 aGroves, Chris.1 aMartin, J.B.1 aYuan, Daoxian.1 aZeng, Sibo.  uhttps://linkinghub.elsevier.com/retrieve/pii/S0012825217306153