Effects of solar radiation modification on the ocean carbon cycle:An earth system modeling study

Solar radiation modification(SRM,also termed as geoengineering)has been proposed as a potential option to counteract anthropogenic warming.The underlying idea of SRM is to reduce the amount of sunlight reaching the atmosphere and surface,thus offsetting some amount of global warming.Here,the authors use an Earth system model to investigate the impact of SRM on the global carbon cycle and ocean biogeochemistry.The authors simulate the temporal evolution of global climate and the carbon cycle from the pre-industrial period to the end of this century under three scenarios:the RCP4.5 CO_(2) emission pathway,the RCP8.5 CO_(2) emission pathway,and the RCP8.5 CO_(2) emission pathway with the implementation of SRM to maintain the global mean surface temperature at the level of RCP4.5.The simulations show that SRM,by altering global climate,also affects the global carbon cycle.Compared to the RCP8.5 simulation without SRM,by the year 2100,SRM reduces atmospheric CO_(2) by 65 ppm mainly as a result of increased CO_(2) uptake by the terrestrial biosphere.However,SRM-induced change in atmospheric CO_(2) and climate has a small effect in mitigating ocean acidification.By the year 2100,relative to RCP8.5,SRM causes a decrease in surface ocean hydrogen ion concentration([H^(+)])by 6% and attenuates the seasonal amplitude of[H^(+)]by about 10%.The simulations also show that SRM has a small effect on globally integrated ocean net primary productivity relative to the high-CO_(2) simulation without SRM.This study contributes to a comprehensive assessment of the effects of SRM on both the physical climate and the global carbon cycle.

Comparison of the carbon cycle and climate response to artificial ocean alkalinization and solar radiation modification

Carbon dioxide removal and solar radiation modification(SRM)are two classes of proposed climate intervention methods.A thorough understanding of climate system response to these methods calls for a good understanding of the carbon cycle response.In this study,we used an Earth system model to examine the response of global climate and carbon cycle to artificial ocean alkalinization(AOA),a method of CO_(2)removal,and reduction in solar irradiance that represents the overall effect of solar radiation modification.In our simulations,AOA is applied uniformly over the global ice-free ocean under the RCP8.5 scenario to bring down atmospheric CO_(2)to the level of RCP4.5,and SRM is applied uniformly over the globe under the RCP8.5 scenario to bring down global mean surface temperature to the level of RCP4.5.Our simulations show that with the same goal of temperature stabilization,AOA and SRM cause fundamentally different perturbations of the ocean and land carbon cycle.By the end of the 21st century,relative to the simulation of RCP8.5,AOA-induced changes in ocean carbonate chemistry enhances global oceanic CO_(2)uptake by 983 PgC and increases global mean surface ocean pH by 0.42.Meanwhile,AOA reduces land CO_(2)uptake by 79 PgC and reduces atmospheric CO_(2)concentration by 426×10^(−6).By contrast,relative to the simulation of RCP8.5,SRM has a minor effect on the oceanic CO_(2)uptake and ocean acidification.SRM-induced cooling enhances land CO_(2)uptake by 140 PgC and reduces atmospheric CO_(2)concentration by 63×10^(−6).A sudden termination of SRM causes a rate of temperature change that is much larger than that of RCP8.5.A sudden termination of AOA causes a rate of temperature change that is comparable to that of RCP8.5 and a rate of ocean acidification that is much larger than that of RCP8.5.

The Effect of Ionizing Radiation and Magnetic Field on Deformation Properties of High Density PolyethylenelAcrylonitrile-Butadiene Composites

The effect of magnetic field and ionizing radiation on the mechanical properties of polymer blends consisting of high density polyethylene （HDPE） and acrylonitrile-butadiene rubber （NBR） has been investigated. The purpose of the work was to create HDPE/NBR blend composites of significantly different compositions （with an excess of HDPE, intermediate ones, and with an excess of NBR） and to investigate the role of composition on mechanical deformation properties under the influence of magnetic field. The investigation has importance from the engineering viewpoint, since thermoplastic composite materials have been used as structural elements in thermonuclear and engineering fields, like wires, insulation materials and others, which are frequently subjected to mechanical loadings under the effect of magnetic field greater than 1 T. One part of the blends has been irradiated with 5 MeV accelerated electrons up to absorbed dose D equal to 150 kGy. Unirradiated and the radiation modified blends have been exposed to a constant magnetic field with induction B equal to 1.0 T, 1.5 T and 1.7 T. It is found that the action of magnetic field decreases the elastic modulus of unirradiated materials. Decrement of elastic modulus is reduced with increase of the content of NBR in composites. It is also found that preliminary irradiation noticeably decreases the effect of magnetic field. Data of the influence of the magnetic field, radiation cross-linking, and the ratio of the components on the creep are also obtained.

Radiation-Assisted Synthesis of Crown Ether-Modified Covalent Organic Frameworks for Lithium Isotope Separation

γ-ray radiation-induced grafting strategy was first employed to immobilize 4-aminobenzo-15-crown-5 onto a covalent organic framework(COF).This endeavor culminated in the successful synthesis of a class of two-dimensional crown ether-modified COFs(named[15C5]n%-(TzDa-G-x%)),marking the maiden utilization of COFs in the realm of^(6)Li/^(7)Li isotope separation.These COFs exhibited swifter adsorption kinetics than alternative adsorbents.Among them,[15C5]_(57%)-(TzDa-G-50%)with its excellent crystallinity,porosity,and stability exhibited the best performance in Li+adsorption and^(6)Li/^(7)Li isotope separation.The Li+adsorption in acetonitrile achieved a capacity of 3.6 mg·g^(−1)within 30 min and a saturation capacity of 7.3 mg·g^(−1).The single-stage separation factor of^(6)Li/^(7)Li isotopes was 1.014±0.001.The results of dynamic adsorption column experiments showed that the packed column made of[15C5]_(57%)-(TzDa-G-50%)maintained stable performance during four cycles of Li+adsorptionelution,with over 99%Li+removal rate in acetonitrile.This crown ether-modified COF has potential application in^(6)Li/^(7)Li isotope separation,and this radiation-assisted synthesis strategy is expected to become universal in the modification of COFs for diverse applications.