In recent decades, global warming under rising CO 2 significantly influences external organic carbon (EOC) input and drying-rewetting processes in terrestrial ecosystems. However, little is known about how soil CO 2 emissions respond to these perturbations, which provides us with a chance to explore potential factors and variability. In this study, a meta-analysis on the responses of CO 2 emissions with or without EOC input in the soil drying-rewetting cycles (DWC) based on 291 observations (included 33 study sites and 11 variables) has been conducted. The results indicated that i) CO 2 emission with the increase of EOC by 284% relative to without EOC under DWC; ii) The effect size of CO 2 emission was the smallest in the forest (+15%) and the largest in the grassland (+1468%); iii) The CO 2 emission effect sizes were substantially greater in complex substrates (+288%) than in simple substrates (+132%), and iv) longer drought period in a DWC can induce more CO 2 emission. The study suggests that terrestrial CO 2 emission may be multi folds in the long drought-rapid rewetting processes under large input of EOC.

Toxic metal-contaminated wastewater is a major environmental issue that requires a practical and cost-effective technological solution. Heavy metal phytoremediation by constructed wetland is becoming more common around the world. Plants are used in phytoremediation to degrade, stabilize, and remove contaminants from soils, water, and waste. The key issues with managing heavy metal phytoremediation plants in an environmentally appropriate manner. The design of CWs for successful phytoremediation in heavy metals contaminated wastewater should not affect the local environment. By-product generation is another crucial part of phytoremediation’s success. Phyto-management has emerged as an alternative strategy in recent years. Phytoremediating plants ( C. indica and A. calamus) biomass has been successfully used in the manufacture of 70 fly-ash bricks. High rate of Cu (96 %), Zn (95 %), (Fe 93), and Cr (91 %) removal from Canna indica and Acorus calamus were found in the present study as compared to the Typha latifoliya, Myriophylhum aquaticum, Ludwigina palustris, Eichhornia crassipes, Schoenoplectus californicus, Cyperus papyrus, and Phragmites australis which indicates C. indica is the high potential for heavy metal removal and can be strongly used for industrial wastewater. In the way, the use of ornamental plants for phytoremediation of contaminated sewage wastewater would also change the landscape of the aquatic environment. This article summarises viable avenues in the method of using phytoremediating plant biomass for environmental protection.