Journal of Polymers and the Environment - Polypropylene carbonate (PPC)/polybutylene succinate (PBS) blends were prepared by melt-blending with terminal epoxy-based hyperbranched polymers (EHBP) as... 相似文献
Environmental Science and Pollution Research - The amount of dissolved organic matter (DOM) in a multi-source watershed is important for complete management and assessing the river basin’s... 相似文献
The generation estimation of retired mobile phones is launched with the sales and new method using the revised sales data and amount of the subscribers. Several assumptions have been made due to the insufficient sources of the data. The sales data of legal mobile phones are calculated with the authoritative and continuous official data. The sales data of smuggled and counterfeit mobile phones in China are also estimated based on the behavior data collected from the questionnaires. The results of generation estimation show that there are 636.52 million mobile phones retired in 2020, compared with 14.44 million in 1999 and several negative values in 2000, 2001, and 2008. The annual total mass of retired mobile phones in China escalated with the contributions of both the increasing generation amount and constant mass of the single unit. There are 50,921.60 ton of mobile phones retired in 2020 compared with 1155.20 ton in 1999, while the peak is 58,131.20 ton in 2019. There are 26,066.80 ton of retired mobile phones are stockpiled in 2020, while 16,152.40 ton and 8702.40 ton of retired mobile phones are reused as a whole unit and recycled, respectively. In the retired mobile phones that are recycled, 4600.50 ton material is recovered and 1216.50 ton components are reused, while 2885.40 ton residues need final disposal. The amount and dynamic characteristics of metals in the retired mobile phones are also calculated. Based on the results, several policy implications are made to improve sustainable management system of retired mobile phones in China.
Phytoplankton variation in large shallow eutrophic lakes is characterized by high spatial and temporal heterogenity. Understanding
the pattern of phytoplankton variation and the relationships between it and environmental variables can contribute to eutrophic
lakes management. In this study Taihu Lake, one of the largest eutrophic fresh water lake in China, was taken as study area.
The water body of Taihu Lake was divided into five regions viz. Wuli bay (WB), Meilian Bay (MB), West Taihu Lake (WTL), Main
Body of Taihu Lake (MBTL) and East Taihu Lake (ETL). Concentrations of chlorophyll-a and the related environmental variables
were determined in each region in the period 2000–2003. Factor analysis and multivariate analysis were applied to evaluate
the interactions between phytoplankton variation and environmental variables. Results showed that the highest average concentrations
of TN, TP and Chl-a were observed in WB, followed in a descending order by MB and WTL, and the lowest concentrations of TN,
TP and Chl-a were observed in MBTL and ETL. Chl-a and TP concentrations in most regions (except ETL) declined during the study
period. It suggested that to some extent the lake was recovering from eutrophication. However, persistent ascending of TN
and NH4–N in all five regions indicated the deteriorating of water quality in the study period. Results of multivariate showed that
the relationships between phytoplankton biomass and environmental variables varied among regions. TP illustrated itself a
controlling role on phytoplankton in WB, MB, WTL and MBTL according to the significant positive relations to phytoplankton
biomass in these regions. Nitrogen could be identified as a limiting factor to phytoplankton biomass in ETL in view of the
positive correlations between TN and phytoplankton and between NH4–N and phytoplankton. Spatial variation of interactions between phytoplankton and environmental parameters suggested proper
eutrophication control measures were needed to restore ecological system in each region of Taihu Lake. 相似文献