Can Green Innovation Improve Regional Environmental Carrying Capacity? An Empirical Analysis from China.

Green innovation has become an important driving force for China's economic transformation and development. This paper selects the 2010-2020 provincial-level regions in China as samples, and adopts a multi-indicator comprehensive evaluation method to comprehensively, objectively and scientifically evaluate the environmental carrying capacity of air pollution in two dimensions: natural resource endowment and human activity impact, and also measures and calculates the green innovation in each province, city and autonomous region to explore the specific impact of green innovation on environmental carrying capacity and its spatial spillover effect; it also explores the heterogeneous effects of green innovation on environmental carrying capacity under different pollution environments. The conclusions show that: (1) Green innovation has a positive impact on environmental carrying capacity. (2) There is a spatial spillover effect of green innovation on environmental carrying capacity. In other words, in areas with higher PM2.5 concentration, that is, lower environmental quality, green innovation has a weaker ability to improve environmental carrying capacity; in areas with lower PM2.5 concentration, that is higher environmental quality, green innovation has a stronger ability to improve environmental carrying capacity. (3) In the process of green innovation affecting environmental carrying capacity, PM2.5 plays the part of a mediating effect, indicating that green innovation is an intermediate transmission mechanism affecting environmental carrying capacity, and the results show that the absolute value of the short-term indirect effect is greater than the absolute value of the short-term direct effect, and the long-term direct effect is greater than the long-term indirect effect.

Research progress in solid carbon source-based denitrification technologies for different target water bodies.

Nitrogen pollution in water bodies is a serious environmental issue which is commonly treated by various methods such as heterotrophic denitrification. In particular, solid carbon source (SCS)-based denitrification has attracted widespread research interest due to its gradual carbon release, ease of management, and long-term operation. This paper reviews the types and properties of SCSs for different target water bodies. While both natural (wheat straw, wood chips, and fruit shells) and synthetic (polybutylene succinate, polycaprolactone, polylactic acid, and polyhydroxyalkanoates) SCSs are commonly used, it is observed that the denitrification performance of the synthetic sources is generally superior. SCSs have been used in the treatment of wastewater (including aquaculture wastewater), agricultural subsurface drainage, surface water, and groundwater; however, the key research aspects related to SCSs differ markedly based on the target waterbody. These key research aspects include nitrogen pollutant removal rate and byproduct accumulation (ordinary wastewater); water quality parameters and aquatic product yield (recirculating aquaculture systems); temperature and hydraulic retention time (agricultural subsurface drainage); the influence of dissolved oxygen (surface waters); and nitrate-nitrogen load, HRT, and carbon source dosage on denitrification rate (groundwater). It is concluded that SCS-based denitrification is a promising technique for the effective elimination of nitrate-nitrogen pollution in water bodies.

Efficacy of heated tourmaline in reducing biomass clogging within woodchip bioreactors.

Woodchip bioreactors can effectively remove waterborne nitrates from subsurface agricultural drainage and prevent the eutrophication of receiving water, but rapid biofilm growth can severely reduce water flux and denitrification efficiency of this practice within a few years. Tourmaline minerals with thermal excitation could generate reactive oxygen species which would inhibit bacterial growth. In this study, laboratory scale woodchip bioreactors were set up to test the anti-clogging and denitrification efficiency of heated woodchips with tourmaline, heated woodchips without tourmaline, and unheated woodchips. The results showed that the heated tourmaline treatment could reduce the clogging and optimize the nitrate removal rate (47.6 g N/m3/day) under all three hydrologic retention times tested (1, 4, and 8 h). Dissolved oxygen and pH values fluctuated with the removal rate and temperature change, while temperature was identified as the key factor impacting the tourmaline treatment. The heated tourmaline treatment had the lowest biofilm growth (lowest DNA concentration), while the 16S rRNA and a higher abundance of nirS-, nirK-, and nosZ-encoding denitrifying bacteria (based on qPCR) confirmed the higher denitrification efficiency of the heated tourmaline treatment.

Extraction of aucubin from seeds of Eucommia ulmoides Oliv. using supercritical carbon dioxide.

Supercritical CO2 was used as solvent for the extraction of aucubin from the seeds of Eucommia ulmoides Oliv. The co-solvent composition was tested and extraction conditions were optimized. Results showed that the best co-solvent was a water-ethanol mixture (1 + 3, v/v), and the highest yield was obtained when the extraction was performed under 26 MPa at extraction and separation temperatures of 55 and 30 degrees C for 120 min, using 6 mL co-solvent/g material at a CO2 flow rate of 20 L/h. In a comparison of the supercritical CO2 and Soxhlet extraction methods, the Soxhlet method needed 3 h to extract 10 g material, whereas the supercritical CO2 extraction technique needed only 2 h to extract 100 g material, thus showing a high extraction capability. The supercritical CO2 extraction produced a higher yield, with a lower cost for the extraction. Owing to the advantages of low extraction temperature, high yield, and ease of separating the product from the solvent, supercritical CO2 extraction is likely to be developed into an ideal technique for the extraction of aucubin, a compound with thermal instability, from the seeds of this plant.