Dissolved organic matter (DOM) plays a key role in many biogeochemical processes, but the drivers controlling the diversity of chemical composition and properties of DOM molecules (chemodiversity) in soils are poorly understood. It has also been debated whether environmental conditions or intrinsic molecular properties control the accumulation and persistence of DOM due to the complexity of both molecular composition of DOM and interactions between DOM and surrounding environments. In this study, soil DOM samples were extracted from 33 soils collected from different regions of China, and we investigated the effects of climate and soil properties on the chemodiversity of DOM across different regions of China, employing a combination of Fourier transform ion cyclotron resonance mass spectrometry, optical spectroscopy, and statistical analyses. Our results indicated that, despite the heterogeneity of soil samples and complex influencing factors, aridity and clay can account for the majority of the variations of DOM chemical composition. The finding implied that DOM chemodiversity is an ecosystem property closely related to the environment, and can be used in developing large-scale soil biogeochemistry models for predicting C cycling in soils.

We, at nanoscale, demonstrated a visualized description of ferrihydrite transformation to crystalline Fe oxides under the impact of Pb and HA.

In soil environments, the sequestration and transformation of organic carbon are closely associated with soil minerals. Birnessite (MnO2) is known to strongly interact with soil dissolved organic matter (DOM), but the microscopic distribution and molecular transformation of soil DOM on birnessite are still poorly understood. In this study, the coupled sorption and oxidation of soil DOM on birnessite were investigated at both the microscopic scale and the molecular level. Spherical aberration corrected scanning transmission electron microscopy (Cs-STEM) results revealed, at the nano- to sub-nanoscale, that DOM was located both on the surfaces and within the interflakes or pore spaces of birnessite, and DOM within the interflakes displayed a higher oxidation state than that on the surfaces. Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR-MS) results suggested that a portion of phenolic compounds were preferentially sorbed and oxidized, resulting in the formation of compounds with higher oxygen contents and polymeric products. Our Cs-STEM and FT-ICR-MS results highlighted the significance of organo-mineral associations in the microscopic mineral structure for the reactivity of organic carbon and provided the molecular evidence for the transformation of soil DOM by birnessite, which contributed to the understanding of the dynamics of soil dissolved organic carbon.

The benefits of applying multi-objective optimization (MOO) in building design have been increasingly recognized in recent decades. The existing or traditional computational design optimization (CDO) approaches mostly focus on optimization problem solving (OPS), as they often conduct optimizations directly by assuming the optimization problems in question are good enough. In contrast, the computational design exploration (CDE) approaches defined in this research mainly focus on optimization problem formulation (OPF), which are considered more essential and aim to achieve or ensure appropriate optimization problems before conducting optimizations. However, the application of the CDE is very limited especially in conceptual architectural design. The necessity of re-formulating original optimization problems and its potential impacts on optimization results are often overlooked or not emphasized enough. This paper proposes a new CDE approach that highlights the knowledge-supported re-formulation of a changeable initial optimization problem. It improves upon the traditional CDO approach by introducing a changeable initial OPF and inserting a CDE module. The changeable initial OPF allows expanding the dimensionality of an objective space and design space being investigated, and the CDE module can re-formulate the changeable optimization problem using the information and knowledge extracted from statistical analyses. To facilitate designers in achieving the proposed approach, an improved computational platform is used which combines parametric modeling software (including simulation plug-ins) and design optimization software. Assisted by the platform, the proposed approach is applied to the conceptual design of an indoor sports building that considers multidisciplinary performance criteria (including architecture-, climate-and structure-related criteria) and a wide range of geometric variations. Through the case study, this paper demonstrates the use of the proposed approach, verifies its benefits over the traditional method, and unveils the factors that may affect the behaviour of the proposed approach. Besides, it also shows the suitability of the computational platform used.

Environmental contextCarbon sequestration and dynamics are influenced by adsorptive fractionation of dissolved organic matter (DOM) on minerals. We found that the molecular fractionation of DOM on ferrihydrite was highly dependent on the presence of Na, Ca and Cu ions in water. These results advance our mechanistic understanding of the dynamic behaviour of DOM, and contribute to predicting carbon cycling and contaminant behaviour in the natural environment. AbstractThe adsorptive fractionation of dissolved organic matter (DOM) at the ferrihydrite and water interface is a key geochemical process controlling DOM compositions and reactivity, thus affecting carbon cycling and contaminant behaviour in the environment. However, the effects of cations on DOM fractionation and the underlying mechanisms are poorly understood. In this study, Fourier-transform ion cyclotron resonance mass spectrometry (FT-ICR-MS) combined with spectroscopic methods were employed to investigate molecular fractionation of DOM on ferrihydrite under different cations in the background electrolytes, including Na, Ca, and Cu ions. The results indicated that DOM fractionation was influenced by the combined effects of cation type, intrinsic molecular property, and extent of DOM adsorption. DOM adsorption on ferrihydrite exhibited the strongest and the weakest fractionation under Na and Ca background electrolytes, respectively. Both Ca and Cu background electrolytes reduced the adsorption of highly unsaturated and phenolic/polyphenolic molecules with high molecular weight and number of O atoms. In addition to the molecular acidity, the complexation of Ca and Cu ions to DOM binding sites and the coagulation effect of divalent cations may affect molecular fractionation. Additionally, DOM fractionation was enhanced with increasing DOM adsorption. Our results contribute to predicting carbon cycling and contaminant behaviour in the natural environment.

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The integration of renewable solar energy-driven interfacial evaporation and photocatalysis has recently emerged as one of the most promising technologies for simultaneous freshwater production and pollutant removal. However, the construction of an advanced integrated system with the merit of a fast supply of water and pollutant molecules remains challenging for efficient solar-driven evaporation and photocatalytic performance. Herein, inspired by the transpiration of plants, we fabricate a biomimetic, vertically channeled polypyrrole/foam-like carbon nitride/poly(vinyl alcohol) hydrogel (PCH) by directional freeze-drying. We prove that the vertically aligned channels not only reduce heat loss and improve energy conversion efficiency but also facilitate the transport of water and organic pollutants to the air−water interface. Benefiting from the advantages above, the PCH evaporator presents a high solar evaporation efficiency of 92.5%, with the evaporation rate achieving 2.27 kg m −2 h −1 under 1 kW m −2 irradiation, exceeding many advanced interfacial solar-driven evaporators. Meanwhile, PCH reaches a degradation efficiency of 90.6% within 1 h when dealing with tetracycline (a typical antibiotic)-polluted water, remarkably higher than that of the hydrogel without vertically aligned channels (68.6%). Furthermore, the as-formed reactive oxygen species effectively kill Grampositive and Gram-negative bacterial in the source water, achieving the all-round water purification. In an outdoor experiment, after 11 h of sunlight irradiation, the tetracycline degradation efficiency and freshwater production of the PCH evaporator rise to 99.0% and 6.2 kg m −2 , respectively. This work highlights the novel biomimetic approach to fabricate multifunctional photothermal materials for simultaneous freshwater production and polluted-water remediation.

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