Abstract
The biogeochemistry of multi-elements, such as sulfur (S), phosphorus (P) and arsenic (As), is interlinked especially at interfaces of soil/sediment–water and plant rhizosphere. To explore the biogeochemical behavior of multi-elements such as S-P-As at interfaces, an in situ and high-resolution technology is required. In this study, we developed an in situ probe (LDHs-DGT) based on the diffusive gradients in thin-films technique using a single binding layer to realize the co-measurement of multi-elements including sulfide and oxyanions. Mg-Al layered double hydroxides (LDHs) were synthesized and incorporated into the probe’s binding layer. Laboratorial characterization showed that the LDHs-DGT probe had a high capacity for sulfide, phosphate and arsenate and can effectively determine their levels across a wide range of solution conditions, i.e., pH from 5 to 8 and ionic strengths from 0.005–0.01 mol L−1 NaNO3. The application potential of the LDHS-DGT probe in capturing the concentration profiles of sulfide and oxyanions across the soil/sediment–water interface at a centimeter scale was demonstrated. The synchronous co-variations of labile sulfide and phosphate were observed along an intact river sediment core, demonstrating the redox driven behaviors of oxyanions at aerobic–anaerobic transition zones. Moreover, the LDHS-DGT probe was further used to acquire the dynamic distributions of multi-elements in the plant rhizosphere at a two-dimensional millimeter scale. Compared to treatments of sodium sulfate and mercaptopygorskite fertilization, the addition of elementary S promoted the reduction of sulfate to sulfide along the whole growth stage and thus inhibited the activation of toxic metals in the rice rhizosphere. Collectively, this study provides a tool for convenient measurement of nutrients and metal(loid)s across soil–water/root interfaces at high resolution and thus, a broad application prospect of the tool in sustainable agriculture is expected.
Highlights
For sustainable agriculture, it is important to keep the balance of mineral elements in soils, and to control the uptake and accumulation of toxic metal(loid)s in crops [1,2]
The results show that LDHS-Diffusive gradients in thin films (DGT) is able to capture the dynamic processes of multi-elements in the rice rhizosphere at a millimeter-scale high spatio-resolution
This work provides a useful tool based on DGT technique for co-measurement of multi-elements, i.e., sulfides (S(-II)) and oxyanions (phosphate, As(V))
Summary
It is important to keep the balance of mineral elements in soils, and to control the uptake and accumulation of toxic metal(loid)s in crops [1,2]. The biogeochemical cycling of mineral elements and toxic metal(loid)s in the environment is highly interlinked. Sulfide may immobilize As by inducing co-precipitation of iron sulfide minerals (e.g., pyrite) and arsenic sulfide (dioecious and realgar) [6,7]. The distribution of elements in agricultural soils, especially at the crop rhizosphere, are highly uneven at both spatial and temporal scales. It is strongly necessary to develop in situ high-resolution tools for co-measurement of nutrients and metal(loid)s at the soil/sediment–water interface and crop rhizosphere
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
