Dramatic changes in climate and soil environments have made growing conditions for crops more challenging. These crops are subject to a range of abiotic stresses in different environments, which can lead to significant yield losses, resulting in economic and environmental damages. Herein, we report a straightforward one-pot hydrothermal method for creating carbon dots codoped with copper and nitrogen (Cu,N-CDs). Under salt stress conditions, Cu,N-CDs demonstrate the ability to alleviate oxidative damage in cucumber seedlings by modulating antioxidant defense mechanisms and scavenging reactive oxygen species (ROS). Cucumber seedling biomass accumulation is greatly enhanced by Cu,N-CDs treatment in the presence of a ROS burst, leading to a notable rise in the dry weight, plant height, and fresh weight. Cu,N-CDs mitigate oxidative damage in cucumber seedlings by activating antioxidant defense systems, specifically enhancing the activities of superoxide dismutase (+34.08%), catalase (+28.11%), peroxidase (+17.54%), and ascorbate peroxidase (+31.54%) to scavenge ROS. Furthermore, Cu,N-CDs can enhance the levels of nonenzymatic elements within the antioxidant system, such as polyphenols (+23.60%), flavonoids (+15.43%), and carotenoid content (+51.73%), which strengthen the scavenging ability of cucumber seedlings against ROS. Meanwhile, Cu,N-CDs can induce a significant increase of soluble sugar and soluble protein content by 27.27 and 32.58%, respectively, which improves the osmotic pressure as well as stress tolerance of plants. Additionally, the accumulation of biomass was aided by the increase in the photosynthetic pigment content that Cu,N-CDs treatment can produce.

The escalating utilization of carbon dots (CDs) in agriculture raises ecological concerns. However, their combined toxicity with arsenic remains poorly understood. Herein, we investigated the combined mitochondrial genotoxicity of CDs and arsenate at environmentally relevant concentrations across successive earthworm generations. Iron-doped CDs (CDs(-Fe)) strongly bound to arsenate and arsenite, while nitrogen-doped CDs (CDs(-N)) exhibited weaker binding. Both CDs enhanced arsenate bioaccumulation without affecting its biotransformation, with most arsenate being reduced to arsenite. CDs(-Fe) generated significantly more reactive oxygen species than did CDs-N, causing stronger mitochondrial DNA (mtDNA) damage. Arsenate further exacerbated the oxidative mtDNA damage induced by CDs(-N), as evidenced by increased reactive oxygen species, elevated 8-oxo-7,8-dihydro-2 '-deoxyguanosine (8-OHdG) levels, and a higher correlation between 8-OHdG and mtDNA damage. This was due to arsenic inhibiting the antioxidant enzyme catalase. This exacerbation was negligible with CDs(-Fe) because their strong binding with arsenic prevented catalase inhibition. Maternal mitochondrial DNA damage was inherited by filial earthworms, which experienced significant weight loss in coexposure groups coupled with mtDNA toxicity. This study reveals the synergistic genotoxicity of CDs and arsenate, suggesting that CDs could disrupt the arsenic biogeochemical cycle, increase arsenate risk to terrestrial animals, and influence ecosystem stability and health through multigenerational impacts.

The pollution of heavy metals such as Cu2+ is still serious and the discharge of sewage of Cu2+ will cause damage to soil environment and human health. Herein, a biomass-based solid-state fluorescence detection platform (CPUCDs) was developed as fluorescent sensor for detection Cu2+ via fluorescence and colorimetric dual-model methods in real time. CPU-CDs was composed of xylan-derived CDs (U-CDs) and cotton cellulose paper, which exhibiting good reusability, non-toxicity, excellent fluorescence characteristics and high biocompatibility. Further, CPU-CDs displayed high effectiveness and sensitivity for Cu2+ with the detection limit as low as 0.14 mu M, which was well below U.S. EPA safety levels (20 mu M). Practical application indicated that CPU-CDs could achieve precision response of Cu2+ change in real environment water samples with good recovery range of 90 %- 119 %. This strategy demonstrated a promising biomass solid-state fluorescence sensor for Cu2+ detection for water treatment research, which is of great significance in dealing with water pollution caused by heavy metal ions.