With the increasing use of metal–organic frameworks (MOFs), they will inevitably enter the environment intentionally or unintentionally. However, the effects of MOFs on plant growth are poorly understood. Here, we investigated the effects of exposure of the rhizosphere to MOFs on plant growth. MIL-101(Cr) was selected as a research model due to its commercial availability and wide use. Soybean plants at the two-leaf stage were subjected to various durations (1–7 days) and concentrations (0–1000 mg/L) of exposure in hydroculture with a control group treated with ultrapure water. We found that MIL-101(Cr) had a positive effect on soybean growth at a lower dose (i.e., 200 mg/L); however, at higher doses (i.e., 500 and 1000 mg/L), it exhibited significant toxicity to plant growth, which is evidenced by leaf damage. To investigate the mechanism of this effect, we used Cr as an indicator to quantify, track, and image MIL-101(Cr) in the plant with laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS). Results indicated that MIL-101(Cr) primarily accumulated in the cortex of roots (up to 40 times higher than that in stems), with limited translocation to stems and negligible presence in leaves and cotyledons. In addition, metabolomic analysis of soybeans indicated that low-dose MIL-101(Cr) could increase the sucrose content of soybean roots to promote plant growth, while a high dose could induce lipid oxidation in roots. This study provides valuable insights into the ecological toxicology of MOFs and underscores the importance of assessing their environmental impact for sustainable agricultural practices.
Qianghong Wu,Youzhi Wu,Sambasivam Sangaraju,Fen Ran
Chromium is a multivalent metal with great development in the energy storage field because it can effectively improve the electrochemical performance of the material. However, chromium(VI) is soluble in water and toxic, which causes serious metal pollution in the environment. In addition, nanoplastics are difficult to degrade and easy to accumulate, which is an urgent environmental problem to be solved. Therefore, we choose Zea mays to absorb chromium ions, nanopolystyrene, nanocarboxylic polystyrene, and their complexes, which can coordinate and decompose with various polymers in Z. mays, and produce coordination, conjugation, mixed valence, and adjacent group effects. Due to the above effects, the UV–vis spectrum of the material is blueshifted; the X-ray photoelectron spectroscopy peaks of Cr 2p have a chemical shift; the pore structure is optimized; the graphitization degree is improved; the content of N, O, and Cr in the material increases; and the elements are evenly distributed. The series of optimization processes makes the electrodes exhibit excellent electrochemical performance in both supercapacitors and lithium-ion batteries. At 0.5 A·g–1, the specific capacitance of the electrode reaches 490 F·g–1. After 10,000 cycles, its specific capacitance remains at 429.3 F·g–1, and the Coulombic efficiency is 89.9%. In lithium-ion batteries, the initial discharging capacity of the electrode is 1071.7 mAh·g–1 at 0.05 A·g–1. After 5000 cycles, its specific capacity can still reach 242 mAh·g–1 at 0.2 A·g–1, and the Coulombic efficiency is above 95%.
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