Identification of dissolved metal contamination of major rivers in the southeastern hilly area, China: distribution, source apportionment, and health risk assessment.

Metal pollution has been a serious problem facing river systems worldwide, which can adversely affect human health through food chain. The goal of this study was to determine the distribution, sources, and health risk of dissolved metals (Cr, Mn, Ni, Cu, Zn, As, Cd, Pb, Al, Sb, V, Co, Mo) in major rivers located in the hilly area of southeastern China (namely, Jiulongjiang River (JL), Minjiang River (MJ), Oujiang River (OJ), Qiantangjiang River (QT), Raohe River (RR), Fuhe River (FR), Xinjiang River (XR), Ganjiang River (GR), Xiushui River (XS), Xiangjiang River (XJ), Zishui River (ZR), Yuanjiang River (YR), Lishui River (LR)) during dry and wet seasons. Results indicated that metal concentrations were spatially and temporally distinct. Metals of Mn, Ni, Cu, Cd, Sb were significantly higher in specific rivers than other metals. And metals of Cr, Ni, As, and Al concentrations were obviously higher in dry season than in wet season. The comparison with drinking water guidelines of China and other countries indicated that waterbodies were polluted higher by Al than other metals at most sites. Metals in JL and XJ may have health risk to local adults with hazard index (HI) > 1. While special attention should be paid to As, which had a potential carcinogenic risk to adults in study area with CR higher than the critical value. Source analysis with statistical method indicated that point and non-point pollutants from anthropogenic activities are the main sources of metals, with the exception of Al, Ni, V, Cr, and Mo that were mainly from natural processes. This study could be useful for the management and protection of the China's Southern hilly area river systems.

Ultrasonic Detection Method for Grouted Defects in Grouted Splice Sleeve Connector Based on Wavelet Pack Energy.

Grouted splice sleeve (GSS) connectors are mainly used in precast concrete structures. However, errors in manual operation during construction cause grouted defects in the GSS connector, which can lead to a negative effect on the overall mechanical properties of the structures. Owing to the complex structure of precast concrete members with a GSS connector, it is difficult to detect grouted defects effectively using traditional ultrasonic parameters. In this paper, a wavelet packet analysis algorithm was developed to effectively detect grouted defects using the ultrasonic method, and a verified experiment was carried out. Laboratory detection was performed on the concrete specimens with a GSS connector before grouting, in which the grouted defects were mimicked with five sizes in five GSS connectors of each specimen group. A simple and convenient ultrasonic detection system was developed, and the specimens were detected. According to the proposed grouted defect index, the results demonstrated that when the grouted defects reached certain sizes, the proposed method could detect the grouted defects effectively. The proposed method is effective and easy to implement at a construction site with simple instruments, and so provides an innovative method for grouted defects detection of precast concrete members.

[Risk factors for asthma in children in Hefei, China].

OBJECTIVE: To investigate the risk factors for asthma in children in Hefei, China and to provide a strategy for asthma control in this region. METHODS: A total of 400 children with a confirmed diagnosis of asthma, as well as 400 children of comparable age, sex, living environment, and family background, who had no respiratory diseases, were selected for a case-control study. A survey questionnaire survey was completed for all children. The obtained data were subjected to univariate and multivariate logistic regression analysis to determine the risk factors for asthma. RESULTS: The logistic regression analysis showed that a family history of allergy, allergic rhinitis, infantile eczema, no breastfeeding, air-conditioning and passive smoking were the risk factors for asthma in children, with odds ratios of 9.63, 7.56, 4.58, 2.16, 1.73, and 1.55 respectively. CONCLUSIONS: In order to reduce the incidence of asthma, we should advocate breast feeding, promote outdoor activities, keep ventilation natural, prevent passive smoking and cure allergic rhinitis.

[Epidemiological survey of childhood asthma in Hefei City, China].

OBJECTIVE: To investigate the cumulative prevalence rate, distribution characteristics, epidemic seasons, predisposing factors and current treatment situation of childhood asthma in Hefei City, China. METHODS: In the investigation, stratified cluster random sampling as well as centralized access and separate home visits were applied, and primary screening forms were filled out. Further confirmation was sought in the primary positive cases, according to the diagnostic criteria for asthma. Statistical analysis was performed to determine the cumulative prevalence rate, current treatment situation and predisposing factors for childhood asthma as well as the distribution characteristics of asthma in children of different ages and sexes. RESULTS: The cumulative prevalence rate of childhood asthma was 5.92%, and there was no significant difference between males and females (6.33% vs 5.42%; P>0.05). The cumulative prevalence rate was highest (8.25%) in children aged 3-6 years. Of the children with acute asthma attack, 42.0% suffered attacks during periods of seasonal transition, and 34.4% suffered attacks at midnight. Among the 552 children with a confirmed diagnosis of asthma, 533 (96.6%) developed asthma due to respiratory tract infection and 312 (56.5%) due to weather change. Most asthmatic children (513/552, 92.9%) received treatment with antibiotics, and 492 asthmatic children (89.1%) were treated with systemic hormones. CONCLUSIONS: The cumulative prevalence rate of childhood asthma is 5.92% in Hefei, and the peak age of onset is 3-6 years. Acute asthma attack occurs mostly during periods of seasonal transition and at midnight. Respiratory tract infection and weather change are the main predisposing factors for childhood asthma. Antibiotics and systemic hormones are still widely used in the treatment of asthma.