Application of high-resolution techniques in the assessment of the mobility of Cr, Mo, and W at the sediment-water interface of Nansi Lake, China.

There are few studies on the simultaneous behavior of chromium (Cr), molybdenum (Mo), and tungsten (W) belonging to group VIB of the periodic table. Herein, based on high-resolution dialysis (HR-Peeper) and diffusive gradients in thin films (DGT) technology, the vertical distribution characteristics of DGT-labile and soluble Cr, Mo, and W in two lakes of Nansi Lake (Weishan Lake and Dushan Lake) were analyzed. In addition, the net diffusion fluxes and R-value (CDGT/Csol) were used to evaluate the mobility and release risk of metals at the sediment-water interface. The results showed that the DGT-labile concentrations of the three metal elements (Cr, Mo, and W) in Weishan Lake were higher than those in Dushan Lake, both in overlying water and sediment. This is mainly due to the dredging of the Dushan Lake area, which can permanently remove the polluted sediment in the lake. Meanwhile, the exogenous input is relatively high near the tourist area of Weishan Island. The net diffusion fluxes indicate that the W has a potential release risk of diffusion to the overlying water in Dushan Lake. The release of Cr, Mo, and W is thought to be related to the reductive dissolution of Fe/Mn (hydr)oxides based on Pearson correlation coefficients. The R-values of Cr and W indicate that Cr and W belong to the partial continuity case. The R-value of Mo was lower than the minimum value, meaning that Mo belongs to the single diffusion type and it is difficult for Mo sediments to supply pore water.

Application of a peer learning and assessment model in an undergraduate pharmacy course.

BACKGROUND: Timely and accurate feedback is a crucial component for effective undergraduate learning. However, with the expansion of university enrolment in China, student numbers have increased rapidly and, in traditional university classrooms, it is often difficult for the teacher - as the only evaluator - to accommodate students' diverse needs and learning styles, and provide timely learning feedback. In our teaching practice research, we combined mutual peer evaluation with cooperative learning, and proposed a peer learning and assessment model (PLAM) that encouraged students to cooperate and compete, leading to greater efficiency in giving feedback. The ultimate goal was to improve students' learning ability. This study aimed to investigate the effect and influencing factors of PLAM in an undergraduate course entitled 'Medicinal Chemistry of Natural Products'. METHODS: We surveyed the entire pharmacy student body (95 students). Each student was required to provide feedback to the other members within the same study group and students in other groups. We evaluated the effectiveness of PLAM in five aspects: basic information, learning attitude, participation, interpersonal relationship, and organizational approach. The questionnaire was administered online using the Star survey platform. Data were exported to Excel and meta-analysis was performed using SPSS. RESULTS: PLAM effectively increased feedback efficiency, enhancing students' learning interest and ability. An ordered logistic regression analysis model was used to analyze the factors influencing the PLAM learning effect. Three factors - learning attitude, participation, and interpersonal relationship - explained up to 71.3% of the model. CONCLUSIONS: The PLAM adopted in this research is an effective learning and evaluation model that can promote collaborative learning and increase learning enthusiasm. It is more suitable for knowledge expansion learning and comprehensive practical learning where teachers cannot be present for the entire process. Students should be encouraged to establish appropriate learning attitudes and a positive group atmosphere. PLAM can positively impact college curriculum learning and could be extended to other teaching domains.

Qualitative and quantitative analysis of the relationship between water pollution and economic growth: a case study in Nansi Lake catchment, China.

Investigation of water pollution-economic growth nexus is an important component for the sustainable development of eco-environment and socio-economy. This study combined the improved Grey relational degree (GRD) model with the environmental Kuznets curve (EKC) to quantitatively and qualitatively investigate the relationships between water pollution and economic growth in Nansi Lake catchment (Jining, Zaozhuang, and Heze) under the context of the Five-Year Plan in Shandong. Results showed that the relational degree of industrial wastewater and economic growth was Heze (0.652) > Zaozhuang (0.581) > Jining (0.538), and of domestic wastewater and economic growth was Jining (0.722) > Heze (0.721) > Zaozhuang (0.650). Meanwhile, the EKC of industrial wastewater rose and then declined, whereas that of domestic wastewater increased upwards. Overall, coordinated development had been gradually obtained between industrial wastewater emissions and economic growth. And, uncoordinated development between domestic wastewater emissions and economic growth still existed, indeed, in recent years it had intensified. Further, domestic wastewater emissions continue to rise, to the point where they now constitute one of the main sources of water pollution in Nansi Lake catchment. Results of this study indicated that combining the improved GRD model with the EKC provides a new approach to comprehensive investigation of the water pollution-economic growth nexus from a qualitative and quantitative perspective.

Health Utility of Pregnant Women Living with HIV/AIDS: Prevention of Mother-to-Child Transmission of HIV (PMTCT) Programs in Yunnan Province: A Cross-Sectional Study.

BACKGROUND: Health utility (HU) is essential to understanding the effects of HIV infection as a chronic disease. No HU data on pregnant women living with human immunodeficiency virus (HIV) in Yunnan Province are available. This study aims to construct a database on HU and explore factors associated with HU by pregnant women living with HIV/acquired immunodeficiency syndrome (AIDS) who were enrolled in the Prevention of mother-to-child transmission of HIV (PMTCT) programs in Yunnan Province. METHODS: A cross-sectional study was conducted in Yunnan Province on pregnant women living with HIV who were selected by convenience sampling. Sociodemographic, HIV-related, social support, and HU data were collected through face-to-face interviews. The European quality of life five-dimensional three-level (EQ-5D-3L) questionnaire and the social support rate scale (SSRS) were applied. RESULTS: One hundred and one pregnant women (mean age of 30.4 ± 5.1 years) participated in the survey. The mean EQ-5D index score and the EQ visual analogue scale (EQ-VAS) score of participants were 0.77 (95% confidence interval [CI] 0.74-0.79) and 75.77 (95% CI 75.00-80.00), respectively. The effect of social support on HU was maintained significant difference even after adjusting for such factors as education level, household income per year, and HIV disclosure, demonstrating a significant difference within EQ-5D index scores and EQ-VAS scores. CONCLUSIONS: Pregnant women living with HIV/AIDS who were enrolled in PMTCT programs reported the same level of HU as other patients living with HIV/AIDS. Integrating measurements of HU by using the EQ-5D-3L questionnaire could be helpful for economic evaluation of the PMTCT program. This study also suggests a potential benefit of appropriate social support.

Spatial trends and pollution assessment for mercury in the surface soils of the Nansi Lake catchment, China.

Surface soil samples collected from Nansi Lake catchment were analyzed for mercury (Hg) to determine its spatial trends and environmental impacts. Results showed that the average soil Hg contents were 0.043 mg kg-1. A positive correlation was shown between TOC and soil Hg contents. The main type of soil with higher TOC contents and lower pH values showed higher soil Hg contents. Soil TOC contents and CV values were both higher in the eastern catchment. The eastern part of the catchment, where the industry is developed, had relatively high soil Hg contents and a banding distribution of high Hg contents was corresponded with the southwest-northeast economic belt. Urban soils had higher Hg contents than rural soils. The urbanization pattern that soil Hg contents presented a decreasing trend from city center to suburb was shown clearly especially in the three cities. Soil Hg contents in Jining City showed a good consistency with the urban land expansion. The spatial trends of soil Hg contents in the catchment indicated that the type and the intensity of human activities have a strong influence on the distribution of Hg in soils. Calculated risk indices showed that the western part of the catchment presented moderately polluted condition and the eastern part of the catchment showed moderate to strong pollution level. The area with high ecological risk appeared mainly along the economic belt.

Distribution, fractionation and risk assessment of mercury in surficial sediments of Nansi Lake, China.

Nansi Lake is composed of four sub-lakes from north to south: Nanyang Lake, Dushan Lake, Zhaoyang Lake and Weishan Lake. An environmental pollution investigation was carried out to determine the fractionation, and pollution assessments of mercury (Hg) in surficial sediments from Nansi Lake. Results showed that the mean concentration of Hg was 3.1 times higher than its background value (0.015 mg kg-1), and the high concentration of Hg which even reached up to five times than the background value in the part of Dushan Lake and Weishan Lake, which indicated that there are obvious spatial differences. The content of Hg was positively correlated with that of total organic carbon, and negatively correlated with that of pH and SiO2 in surface sediments. An improved Tessier sequential extraction procedure was used to study the fractions of Hg in sediments. The results indicated that Hg existed primarily in the fraction of residual, which accounts for 58.4% of total mercury (THg), and the percentage of extractable Hg was only 1.93% of total mercury. High concentrations of mercury of non-residual phase were found in part lake area from the Nanyang Lake and the Weishan Lake, which indicating a higher potential ecological risk relative to the other lake areas. Based on the values of enrichment factor and geo-accumulation index, most part of Dushan Lake and Nanyang Lake and Weishan Lake were in a moderate pollution. And based on the fractionation of mercury, risk assessment code of Hg exhibited low risks to the environment in Nansi Lake.

Geochemical fractions and risk assessment of trace elements in soils around Jiaojia gold mine in Shandong Province, China.

Soils located adjacent to the Jiaojia gold mine were sampled and analyzed to determine the degree of which they were contaminated by trace elements (Hg, As, Cd, Pb, Cu, and Zn) in Shandong Province, China. All 18 samples exhibited mean Hg, As, Cd, and Pb concentrations in excess of local background values, while the mean concentrations of Cu and Zn were below the background values. In addition, the concentrations of trace elements in gold smelter (GS) soils were higher than in the gold mine (GM) soils. The result from a modified Tessier sequential extraction procedure was that with the exception of Cu in soils near the smelter, the trace elements were predominantly associated with the residual fraction. After residual fraction, most Hg was mainly humic acid and strong organic fraction, while most As was the humic acid. Cd was associated with the water soluble, ion exchange, and carbonate fractions compared with the other trace elements. Furthermore, Cu, Pb, and Zn were more concentrated in the humic acid and Fe/Mn oxide fraction. The fractions of trace elements were affected by soil pH and Ec (Electrical conductivity). The humic acid fraction of Hg as well as the ion exchange fraction of Cd and Zn displayed negative correlations with soil pH. The strong organic fraction of Hg, the Fe/Mn oxide fraction of Cd, and the carbonate fraction of Zn were positively related to the soil Ec. The strong organic fraction and ion exchange fraction of Zn were negatively related to soil Ec. However, the ion exchange and carbonate fractions of As showed significant positive correlations with soil pH. A calculated individual availability factor (A f (i) ) is used; the values of each trace element in the soils are in the following order: Cu > Cd > Pb > Zn > As > Hg. When combined with a risk assessment code, data suggest that Hg, As, Pb, and Zn levels showed low risk for the environment, whereas Cd levels in soils adjacent to the GM and Cu levels in soils adjacent to the GS showed medium risk to the environment, and Cd levels in soils adjacent to the GS exhibited higher environment risk.

Geochemical speciation and pollution assessment of heavy metals in surface sediments from Nansi Lake, China.

Sixteen surface sediment samples were collected from Nansi Lake to analyze geochemical speciation of heavy metals including Cd, As, Pb, Cr, and Zn, assess their pollution level, and determine the spatial distribution of the non-residual fraction. Results showed that Cd had higher concentrations in water-soluble and exchangeable fractions. As and Pb were mainly observed as humic acid and reducible fractions among the non-residual fractions, while Cr and Zn were mostly locked up in a residual fraction. The mean pollution index (P i) values revealed that the lower lake generally had a higher enrichment degree than the upper lake. Cd (2.73) and As (2.05) were in moderate level of pollution, while the pollution of Pb (1.80), Cr (1.27), and Zn (1.02) appeared at low-level pollution. The calculated pollution load index (PLI) suggested the upper lake suffered from borderline moderate pollution, while the lower lake showed moderate to heavy pollution. Spatial principle component analysis showed that the first principal component (PC1) including Cd, As, and Pb could explain 56.18 % of the non-residual fraction. High values of PC1 were observed mostly in the southern part of Weishan Lake, which indicated greater bioavailability and toxicity of Cd, As, and Pb in this area.

Assessment of heavy metal contamination in the sediments of Nansihu Lake Catchment, China.

At present, anthropogenic contribution of heavy metals far exceeds natural input in some aquatic sediment, but the proportions are difficult to differentiate due to the changes in sediment characters. In this paper, the metal (Al, Fe, K, Mg, Ca, Cr, Cu, Ni, and Zn) concentrations, grain size, and total organic carbon (TOC) content in the surface and core sediments of Nansihu Lake Catchment (the open lake and six inflow rivers) were determined. The chemical speciations of the metals (Al, Fe, Cr, Cu, Ni, and Zn) in the surface sediments were also analyzed. Approaches of factor analysis, normalized enrichment factor (EF) and the new non-residual fractions enrichment factor (K(NRF)) were used to differentiate the sources of the metals in the sediments, from detrital clastic debris or anthropogenic input, and to quantify the anthropogenic contamination. The results indicate that natural processes were more dominant in concentrating the metals in the surface and core sediments of the open lake. High concentration of Ca and deficiency of other metals in the upper layers of the sediment core were attributed to the input of carbonate minerals in the catchment with increasing human activities since 1980s. High TOC content magnified the deficiency of the metals. Nevertheless, the EF and K(NRF) both reveal moderate to significant anthropogenic contamination of Cr, Cu, Ni, and Zn in the surface sediments of Laoyun River and the estuary and Cr in the surface sediments of Baima River. The proportion of non-residual fractions (acid soluble, reducible, and oxidizable fractions) of Cr, Cu, Ni, and Zn in the contaminated sediments increased to 37-99% from the background levels less than 30%.