Social capital can enhance community resilience to environmental change. Productive and trusted relations among social actors and effectual social norms can help local residents share resources, information and risks. The main objective of our study is to understand the ways in which social attributes and risk considerations influence adoption of resilient economic measures by individuals for reducing potential losses due to catastrophic rainstorm and flooding. This article provides evidence from China on how social capital contributes to anticipatory adaptation to environmental change. The inquiry is based on structured interviews with local residents of Tianjin, a flood-prone port city in China, and a standard regression analysis. Findings show that the intention to make preparation increases with the levels of social expectation, social relationship, and institutional trust. Perceived risk and damage experience, however, have no significant impacts. This suggests that building social capacity and trust will be more effective in enhancing community resilience than merely increasing awareness of hazard risks. We call for greater efforts on strengthening the capacity of formal and informal communal institutions. The structural changes required, however, are challenging.

Abstract:Considering the highly stochastic nature of the hydrological process, wavelet transform was used to analyse the characteristics, trends and causes of variations in annual run-off into Tianjin in the Haihe River Basin. Run-off was steadily declining due to climate change and human activity and a significant decrease in run-off along the time series was discovered around the 1960s; however, the change in precipitation was insignificant. The time series of run-off was heavily influenced by a nonlinear feature and mainly influenced by the natural climate before the 1960s, but after the 1970s the change remained steady, with an annual run-off that fluctuated between 0Ð2 and 48Ð4 mm and was maintained at a low level (9Ð3 mm). The main cause of the run-off decline in the 1960s was that more than 1900 reservoirs with a total holding capacity of up to 83 mm were constructed in the upper and middle reaches, which controlled 85% of the total run-off. These projects have played an active role in the reservoir action and water conservation since they were implemented. At the beginning of the 1980s, the demand for water resources increased with the rapid growth of the population and the large-scale development of industry and agriculture in the Haihe River Basin, which caused a reduction in run-off into Tianjin. Overall, the hydrological effects of water storage projects regulating river run-off were beneficial to flood control, but might cause a serious reduction in river run-off into Tianjin and the lower reaches of the basin. In addition, a decrease in annual precipitation and changes in temperature in Northern China have also had an adverse effect on natural run-off, which caused a greater decline in water resources, but this did not have a powerful influence on the overall decline in the run-off.

Samples of class F coal fly ash (levels I, II, and III), slag, coal, atmospheric deposition, and soils collected from Tianjin, China, were analyzed using U.S. Environmental Protection Agency (U.S. EPA) Method 3052 and a sequential extraction procedure, to investigate the pollution status and mobility of Hg. The results showed that total mercury (HgT) concentrations were higher in level I fly ash (0.304 µg/g) than in level II and level III fly ash and slag (0.142, 0.147, and 0.052 µg/g, respectively). Total Hg in the atmospheric deposition was higher during the heating season (0.264 µg/g) than the nonheating season (0.135 µg/g). Total Hg contents were higher in suburban area soils than in rural and agricultural areas. High HgT concentrations in suburban area soils may be a result of the deposition of Hg associated with particles emitted from coal-fired power plants. Mercury in fly ash primarily existed as elemental Hg, which accounted for 90.1, 85.3, and 90.6% of HgT in levels I, II, and III fly ash, respectively. Mercury in the deposition existed primarily as sulfide Hg, which accounted for 73.8% (heating season) and 74.1% (nonheating season) of HgT. However, Hg in soils existed primarily as sulfide Hg, organo-chelated Hg and elemental Hg, which accounted for 37.8 to 50.0%, 31.7 to 41.8%, and 13.0 to 23.9% of HgT, respectively. The percentage of elemental Hg in HgT occurred in the order fly ash > atmospheric deposition > soils, whereas organo-chelated Hg and sulfide Hg occurred in the opposite order. The present approach can provide a window for understanding and tracing the source of Hg in the environment in Tianjin and the risk associated with Hg bioaccessibility.

Seventeen sediment samples at three representative sites (the Yuqiao Reservoir, the Haihe River and the Haihe River Estuary) in Tianjin, northern China, were analyzed to investigate the pollution status, accumulation and mobility of mercury (Hg). The results show that the Haihe River has to be considered as moderate to strongly contaminated with Hg (2 < mean I(geo) = 2.35 < 3), where total Hg contents were ca. 3 to 24 orders of magnitude greater than the regional background value. The sediments collected near a coal-fired power plant in an urban area were found to have very high Hg concentrations, which were significantly related to Hg emissions from coal-fired utility boilers. In the Yuqiao Reservoir, the surface sediments have to be considered as unpolluted with Hg (mean I(geo) = -0.05 < 0) and the Haihe River Estuary sediments have to be considered as unpolluted to moderately polluted with Hg (0 < mean I(geo) = 0.18 < 1). Sediment-bound Hg in the Yuqiao Reservoir and the Haihe River Estuary was found to be predominantly associated with the organo-chelated phase of the sediment (38.3% and 50.5%, respectively). However, unlike the Yuqiao Reservoir and the Haihe River Estuary, Hg in the Haihe River sediments existed mainly as sulfide Hg and elemental Hg, which accounted for 54.2% and 30.7% of total Hg, respectively. The availability of this element seemed restricted. The majority of Hg contamination in the Haihe River sediments had been attributed to historic and modern atmospheric deposition and Hg released from the Haihe River sediments didn't seem to be an important pollutant pathway into the Haihe River Estuary. The results provide new insights into Hg contamination in this region.

Megacities situated on flood plains face escalating risks of waterlogging and inundation. Tianjin is one of these megacities in China where residents are exposed to these risks and not well prepared for their consequences. Government policies should support the most vulnerable and less resilient groups. This study can inform policy-making by identifying the socio-economic characteristics of those who are financially better prepared for the consequences of catastrophic rainstorms and flooding. A structured questionnaire survey was administered to 332 Tianjin residents. Results confirm that financial conditions crucially determine household resilience to these natural hazards. Lower-income and less educated urban residents have lower resilient capacity. Weak engagement in the community, including residential committees and other organisations, is related to lower capacity to cope with the economic consequences of extreme weather events. Less resilient groups are therefore those who are subject to urban poverty and have limited social capital. Tianjin and other cities in the developing world require resilience strategies that attend to this segment of urban population.