Anthropogenic Carbon Particles Trigger Oxidative Reprogramming of Mangrove Physiology and Disrupt Rhizosphere...

Area of Science:

• Environmental Science
• Ecology
• Biogeochemistry

Background:

• Mangrove ecosystems are crucial carbon sinks threatened by anthropogenic pollutants.
• Polystyrene nanoplastics (PS NPs) and biochar (BC) are emerging contaminants impacting soil health.
• Understanding their effects on Avicennia marina, a key mangrove species, is vital for conservation.

Purpose of the Study:

• To investigate the physiological, microscopic, and multiomic responses of Avicennia marina seedlings and their rhizosphere to PS NP and BC.
• To evaluate the transport and impact of these contaminants within the plant and soil system.
• To elucidate the effects on microbial communities and nutrient cycling.

Main Methods:

• A 150-day waterlogged pot experiment using Avicennia marina seedlings.
• Subsurface application of PS NPs and BC.
• Integrated analysis including physiological measurements, microscopy, and multiomics (metabolomics, transcriptomics, microbial community analysis).

Main Results:

• PS NPs showed limited upward transport but caused significant root damage, chloroplast disintegration, and oxidative stress, decreasing photosynthetic efficiency (ΦPSII).
• BC induced severe root-tip disintegration, reduced urease activity, and decreased ΦPSII, with negative effects amplified in low-oxygen conditions.
• Both treatments altered microbial network connectivity and carbon-nitrogen cycling genes; PS NP promoted carbon degradation, while BC stimulated compensatory carbon fixation.

Conclusions:

• Both PS NPs and BC disrupt the critical soil-microbe-plant interface in mangrove ecosystems.
• BC's detrimental effects are exacerbated under the oxygen-limited conditions typical of mangrove sediments.
• These findings highlight the significant ecological risks posed by nanoplastics and biochar to vital coastal carbon sinks.