Improved Anthropogenic Mercury Emission Inventories for China from 1980 to 2020: Toward More Accurate Effectiveness Evaluation for the Minamata Convention.

Anthropogenic mercury (Hg) emission inventories are crucial for the effectiveness evaluation of the Minamata Convention on Mercury. In this study, we developed an integrated Dynamic Inventory for Mercury Emission (DIME) model and improved the accuracy of emission estimates for primary sources in China. Long-term historical speciated Hg emission inventories for China were established. The total Hg emissions increased from 217.0 t in 1980 to 357.8 t in 2020 with a peak value of 506.6 t in 2010. Three stages with distinct leading drivers were identified. At Stage 1 (1980-1997), Hg emissions doubled with the rapid growth of economy; the driver was offset by the increase of dust and SO2 control measures at Stage 2 (1997-2010) except for cement production; and co-benefits from strict control measures induced the decoupling of Hg emissions from the economy at Stage 3 (2010-2020). The ultralow emission (ULE) retrofits in key industries had pronounced Hg removal efficiencies. Large emission reduction potential still exists in the cement industry. The improved emission estimation methods for key sectors, the consistency in methodology for historical Hg emission inventories, and the more accurate spatial distribution of speciated Hg emissions in this study provide a practical toolkit for the effectiveness evaluation of the Minamata Convention.

Impacts of Removal Compensation Effect on the Mercury Emission Inventories for Nonferrous Metal (Zinc, Lead, and Copper) Smelting in China.

Nonferrous metal smelting (NFMS) is one of the key sources of mercury (Hg) emissions to the air and cross-media Hg transfer in China. In this study, a "Hg removal compensation effect" between upstream and downstream air pollution control devices (APCDs) in NFMS was uncovered based on the investigation of field test data. The relationships between the Hg concentration in flue gas and the Hg removal efficiencies of typical APCDs were established, and an advanced probabilistic mass flow model regarding this effect was developed. Model comparison shows that the probabilistic essence of the advanced model prevents the underestimation of the deterministic model caused by using the geometric means of the Hg contents of metal concentrates, and the consideration of the removal compensation effect leads to more accurate estimation of the overall Hg removal efficiency of cascaded APCDs. The Hg emission abatement in the NFMS sector from 2010 to 2017 was evaluated to be 55.6 t, which was 13.5% higher than the estimate without considering the Hg removal compensation effect. The overall uncertainty of the improved model was reduced. This study provides a new methodology for more accurate evaluation of the effectiveness of the national implementation plan for the Minamata Convention on Mercury.

[Cd Pollution and Safe Planting Zoning in Paddy Soils: A Case Study in a District of Chongqing].

Rice has a strong ability to accumulate Cd in soil, and it is of great significance to study Cd pollution and safe planting zoning in paddy soils. In this work, 300 sets of paddy soil-rice samples were simultaneously collected in 22 towns in a District of Chongqing, and soil pH, soil total and available Cd contents, and brown rice Cd contents were determined. Soil Cd pollution was assessed using the geoaccumulation index, bioconcentration factor, and the single-factor pollution index. Based on the Cd pollution indices of soil and brown rice, safe planting zoning for rice was determined. The results showed that the paddy soils were generally acidic, and total Cd contents ranged from 0.09 mg·kg-1 to 1.60 mg·kg-1, with 35.0% of sites exceeding the risk screening value. The Cd contents of the brown rice ranged from 0.002 mg·kg-1 to 0.808 mg·kg-1 and exceeded the food safety limit in 13.7% of cases. Pearson correlation analysis showed that the Cd content of brown rice was significantly positively correlated with soil total and available Cd (P<0.01). The pollution evaluation indicated that significant Cd accumulation occurred in the paddy soils, with some areas showing light-to-moderate pollution levels. The enrichment coefficients of rice to soil Cd ranged from 0.004 to 1.72. Overall, the paddy soils in the studied area were considered generally safe with respect to Cd pollution, with low-risk areas distributed in the south, west, and east, whereas some medium-high risk areas were detected in eight towns.

[Preliminary survey on the host of Angiostrongylus cantonensis in three plateau lakes of Yunnan Province].

OBJECTIVE: To investigated the intermediate hosts of Angiostrongylus cantonensis in three plateau lakes of Yunnan Province, and analyze the effect of temperature on A. cantonensis during 1991-2010. METHODS: An epidemiological investigation of angiostrongyliasis cantonensis in Erhai Lake, Fuxian Lake and Xingyun Lake was conducted from April to September in 2012. Snails were examined for the third stage larvae by enzyme digestion or lung examination. Rodents were captured in the fields, and their hearts and lungs were dissected for adult worms. The potential distribution of A. cantonensis and its main intermediate host Pomacea canaliculata were predicted based on degree-day models using GIS technique. RESULTS: A total of 4 950 snails were collected, belonging to 4 species, P. canaliculata, Cipangopaludina chinensis, Bellamya aeruginosa, and B. quadrata. 174 rodents were captured, belonging to 5 species. No positive samples were found. The potential distribution map showed that the distribution of A. cantonensis and P. canaliculata in Yunnan would expand with the rise of temperature, and with the passage of time they could complete one generation in the region which couldn't finish one generation in one year along with time passing. CONCLUSION: A. cantonensis are not found in the hosts. The natural environment and ecological system of the three lakes match the condition of A. cantonensis transmission.

Preparation, characterization, and antitumor activity of paclitaxel-loaded folic acid modified and TAT peptide conjugated PEGylated polymeric liposomes.

Targeting therapy is a promising strategy for enhancing the therapeutic potential of chemotherapeutic agents. In this study, we report the construction of a multifunctional drug delivery system, termed folic acid modified and TAT peptide conjugated PEGylated polymeric liposomes (FA-TATp-PLs), which is originally derived from octadecyl-quaternized lysine modified chitosan and cholesterol. Our data revealed that FA-TATp-PLs have a particle size of about 60 nm with a zeta potential of about 30 mV, a low burst release effect within the first day, a sustained release for the next 14 days in vitro as well as an instant cellular uptake by folate receptor-overexpressing KB human nasopharyngeal carcinoma cells. In vitro cytotoxicity of paclitaxel-loaded FA-TATp-PLs in KB cells was superior to that of Taxol(®). Furthermore, a comparable antitumor efficacy of paclitaxel-loaded FA-TATp-PLs and Taxol(®) was observed at the same doses in murine models bearing nasopharyngeal carcinoma. These results demonstrate that the paclitaxel formulation not only exhibits a higher antitumor activity but also significantly reduces the toxicity and improves the bioavailability as compared to that of free paclitaxel for the treatment of nasopharyngeal carcinoma. Taken together, our findings indicate that paclitaxel-loaded FA-TATp-PLs are a promising nano-sized drug formulation for future cancer therapy.

Paclitaxel-loaded, folic-acid-targeted and TAT-peptide-conjugated polymeric liposomes: in vitro and in vivo evaluation.

OBJECTIVE: Folic acid and TAT peptide were conjugated on the octadecyl-quaternized, lysine-modified chitosan-cholesterol polymeric liposomes (FA-TATp-PLs) to investigate their potential feasibility for tumor-targeted drug delivery. METHODS: FA-TATp-PLs encapsulating paclitaxel or calcein were synthesized and characterized. Cellular uptake of PLs, FA-PLs, TATp-PLs and FA-TATp-PLs was studied by confocal laser scanning microscopy (CLSM) in folate receptor (FR)-positive KB nasopharyngeal epidermal carcinoma cells and FR-deficient A549 lung cancer cells. In vitro and in vivo antitumor activity of paclitaxel-loaded FA-TATp-PLs were also evaluated in KB and A549 cells as well as in a murine KB xenograft model. RESULTS: Our data showed that 80% paclitaxel released from FA-TATp-PLs in 2 weeks. Different from other various PLs, CLSM analyses showed that FA-TATp-PLs had a significantly high efficient intracellular uptake in both KB and A549 cells. These data revealed the targeting effects of folate decoration, the transmembrane ability of TAT peptide as well as a synergistic interaction between them. In addition, paclitaxel-loaded FA-TATp-PLs exhibited a more superior antitumor effect in vitro and in vivo as compared to that with Taxol. CONCLUSIONS: FA-TATp-PLs possessing both targeting effect and transmembrane ability may serve as a promising carrier for the intracellular delivery of therapeutic agents.