Abstract Climate change will alter the capacity of carbon sequestration, and the risk assessment of carbon sequestration for terrestrial ecosystems will be helpful to the decision-making for climate change countermeasures and international climate negotiations. Based on the net ecosystem productivity of terrestrial ecosystems simulated by Atmosphere Vegetation Integrated Model, each grid of the risk criterion was set by time series trend analysis. Then the risks of carbon sequestration of terrestrial ecosystems were investigated. The results show that, in the IPCCSRES-B2 climate scenario, climate change will bring risks of carbon sequestration, and the high-risk level will dominate terrestrial ecosystems. The risk would expand with the increase of warming degree. By the end of the long-term of this century, about 60% of the whole country will face the risk; Northwest China, mountainous areas in Northeast China, middle and lower reaches plain of Yangtze River areas, Southwest China and Southeast China tend to be extremely vulnerable. Risk levels in most regions are likely to grow with the increase of warming degree, and this increase will mainly occur during the near-term to mid-term. Northwest China will become an area of high risks, and deciduous coniferous forests, temperate mixed forests and desert grassland tend to be extremely vulnerable. 相似文献
● Fe3O4 NPs increased the biomass and chlorophyll content of hemp clones. ● Fe3O4 NPs penetrated and were internalized by root cells. ● Fe3O4 NPs induced the alteration of metabolite profiles in hemp leaves. ● The psychoactive compound THC in hemp leaves was significantly down-regulated. We investigated the effect of iron oxide nanoparticles (Fe3O4 NPs, ~17 nm in size) on the phenotype and metabolite changes in hemp (Cannabis sativa L.), an annual crop distributed worldwide. Hemp clones were grown in hydroponic cultures with Fe3O4 NPs (50, 100, 200, or 500 mg/L) for four weeks. TEM and ICP-MS were used to determine Fe3O4 NPs uptake and translocation. LC-MS-based metabolomics was employed to explore the deep insight into the effect of Fe3O4 NPs on hemp plants. The results revealed that plant growth enhanced gradually with increasing concentrations of given NPs up to 200 mg/L, which improved the fresh weight and dry weight by 36.13% and 74.68%, respectively, compared to the control. Even at a high dose (500 mg/L), Fe3O4 NPs promoted plant growth, including increased biomass and tissue length. NPs significantly increased the iron and chlorophyll content in plant tissues Increased catalase activity and reduced hydrogen peroxide content in hemp leaves suggested that the Fe3O4 NPs activated the defense system. TEM showed that NPs were abundantly attached to the cell wall and dispersed throughout the root cells. Metabolomics revealed that Fe3O4 NPs induced metabolic reprogramming in hemp leaves, including the up-regulation of carbohydrates and organic acids, and down-regulation of antioxidants, especially tetrahydrocannabinol (THC). The significantly up-regulated metabolites, including peonidin and 2-hydroxycinnamic acid, could be involved in photosynthesis in hemp plants. These results demonstrate the potential of Fe3O4 NPs for promoting hemp growth and decreasing the THC content at low doses. 相似文献
In this study, the performance of shortcut nitrification–denitrification (SCND) at different TC and SD stress conditions (0 μg/L, 1–97 days; 100 μg/L, 98–138 days; 500 μg/L, 139–175 days) was investigated. Higher level antibiotic stress (500 μg/L) led to the serious deterioration of nitrogen removal, and denitrification was more sensitive to antibiotic stress than nitrification. The dynamics of antibiotic resistance genes (ARGs) and microbial community were revealed by quantitative real-time PCR and 16S rDNA high-throughput sequencing, respectively. Tet-genes (tetA, tetQ, tetW), sul-genes (sulI, sulII), and mobile genetic element (intI1) in activated sludge increased by 1.2?~?2.5 logs with long-term exposure of antibiotic stress, and sulI, tetA, tetQ, and tetW were significantly positively correlated with intI1. Long-term antibiotics stress caused the decrease of most denitrifiers, and five genera were identified as the potential host of ARGs. The key impact factors of SCND drove the dynamics of ARGs and microbial community. Except for sulII gene, DO and FA were significantly positively correlated with ARGs, while FNA, NAR, and NO2?-N showed opposite effects to ARGs. Overall, maintaining relative lower DO, higher FNA, NAR, and NO2?-N conditions are not only benefit to the stable operation of SCND, but may also conducive to the control of ARG dissemination. This study provides theoretical basis on the control of ARGs in the SCND process.
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