Greenhouse gas emissions and environmental drivers in different natural wetland regions of China.

Wetlands sequestrate carbon at the highest rate than any other ecosystems on Earth. However, the spatial and temporal dynamics of GHGs emissions from the wetland ecosystems in China are still elusive. We synthesized 166 publications that contain 462 in situ measurements of GHGs emissions from the natural wetlands in China, and further analyzed the variability and the drivers of GHGs emissions in eight subdivisions of China's wetlands. The results show that the current studies are mainly concentrated in the estuaries, Sanjiang Plain, and Zoige wetlands. The average CO2 emissions, CH4 fluxes and N2O fluxes from Chinese wetlands were 218.84 mg·m-2·h-1, 1.95 mg·m-2·h-1 and 5.8 × 10-2 mg·m-2·h-1, respectively. The global warming potential (GWP) of China's wetlands was estimated to be 1881.36 TgCO2-eq·yr-1, with CO2 emissions contributing more than 65% to the GWP value. The combined GWP values of Qinghai-Tibet Plateau wetlands, coastal wetlands and northeastern wetlands account for 84.8% of GWP of China's wetlands. Correlation analysis showed that CO2 emissions increased with the increasing mean annual temperature, elevation, annual rainfall, and wetland water level, but decreased with soil pH. CH4 fluxes increased with the mean annual temperature and soil water content but decreased with the redox potential. This study analyzed the drivers of GHGs emissions from wetland ecosystems at the national scale, and GWP values of eight wetland subregions of China were comprehensively assessed. Our results are potentially useful for the global GHGs inventory, and can help assess the response of GHGs emissions of wetland ecosystem to environmental and climate change.

Variation in community structure and network characteristics of spent mushroom substrate (SMS) compost microbiota driven by time and environmental conditions.

Global mushroom production is growing rapidly, raising concerns about polluting effects of spent mushroom substrate (SMS) and interest in uses in composts. In this study, SMS composting trials and high-throughput sequencing were carried out to investigate to better understand how the structure, co-occurrence patterns, and functioning of bacterial and fungal communities vary through compost time and across environmental conditions. The results suggested that both bacterial and fungal microbiota displayed significant variation in community composition across different composting stages. Enzyme activity levels showed both directional and fluctuating changes during composting, and the activity dynamics of carboxymethyl cellulase, polyphenol oxidase, laccase, and catalase correlated significantly with the succession of microbial community composition. The co-occurrence networks are "small-world" and modularized and the topological properties of each subnetwork were significantly influenced by the environmental factors. Finally, seed germination and seedling experiments were performed to verify the biosafety and effectiveness of the final composting products.

Insight into the characterization and digestion of lotus seed starch-tea polyphenol complexes prepared under high hydrostatic pressure.

Complex starch is gaining research attention due to its unique physicochemical and functional properties. In this study, the effects of green tea polyphenols on the properties and digestion of lotus seed starch under high hydrostatic pressure were investigated. The particle size, swelling power, solubility, crystallization, morphology and thermal properties of lotus seed starch were affected by green tea polyphenols. These may be due to the formation of non-inclusive complexes between lotus seed starch and green tea polyphenols. The morphology and green tea polyphenols distribution of the complexes were determined by scanning electron microscopy and confocal laser scanning microscopy. In addition, slow digestion properties of starch were realized under a dynamic in vitro rat stomach-duodenum model and the erosion of granules by amylase gradually decreased by scanning electron microscopy. Furthermore, green tea polyphenols were shown to be able to form V-type inclusion complex with amylose via high hydrostatic pressure.

Physicochemical properties and digestion of the lotus seed starch-green tea polyphenol complex under ultrasound-microwave synergistic interaction.

Complex starch is gaining research attention due to its unique physicochemical and functional properties. Lotus seed starch (LS) suspensions (6.7%, w/v) with added green tea polyphenols (GTPs) (10%, w/w) were subjected to ultrasound (200-1000 W)-microwave (150-225 W) (UM) treatment for 15 min. The effects of UM treatment on the physicochemical properties of the LS-GTP system were investigated and exceeded that of microwave or ultrasound alone. The properties (morphology, X-ray diffraction pattern and so on) were affected by GTPs to various extents, depending on ultrasonic power. These influences may be explained by the non-covalent interactions between GTPs and LS. V-type LS-GTP inclusion complex and non-inclusive complex formation were observed. Their morphology and the distribution of GTPs molecules within them were estimated using scanning electron microscopy and confocal laser scanning microscopy. Furthermore, the digestion of LS-GTP complex was investigated by a dynamic in vitro rat stomach-duodenum (DIVRSD) model, lower digestion efficiency of LS has been achieved and the residues showed gradual improvement in morphology. These all experimental results do provide new insight into the complex starch production.

Assessment of ecological and human health risks of heavy metal contamination in agriculture soils disturbed by pipeline construction.

The construction of large-scale infrastructures such as nature gas/oil pipelines involves extensive disturbance to regional ecosystems. Few studies have documented the soil degradation and heavy metal contamination caused by pipeline construction. In this study, chromium (Cr), cadmium (Cd), copper (Cu), nickel (Ni), lead (Pb) and zinc (Zn) levels were evaluated using Index of Geo-accumulation (Igeo) and Potential Ecological Risk Index (RI) values, and human health risk assessments were used to elucidate the level and spatial variation of heavy metal pollution risks. The results showed that the impact zone of pipeline installation on soil heavy metal contamination was restricted to pipeline right-of-way (RoW), which had higher Igeo of Cd, Cu, Ni and Pb than that of 20 m and 50 m. RI showed a declining tendency in different zones as follows: trench > working zone > piling area > 20 m > 50 m. Pipeline RoW resulted in higher human health risks than that of 20 m and 50 m, and children were more susceptible to non-carcinogenic hazard risk. Cluster analysis showed that Cu, Ni, Pb and Cd had similar sources, drawing attention to the anthropogenic activity. The findings in this study should help better understand the type, degree, scope and sources of heavy metal pollution from pipeline construction to reduce pollutant emissions, and are helpful in providing a scientific basis for future risk management.