In this study, the current situation of five types of toxic organics and endocrine disrupters in the sediments of rivers around Beijing, i.e., polycyclic aromatic hydrocarbons (PAHs), phthalic acid esters (PAEs), organic chlorinated pesticides (OCPs), estrogens (Es), and bisphenol A (BPA), which included 56 contaminants, was analyzed and compared with that registered by the historical literatures. The ecological risks were also assessed. The total concentration of PAHs, PAEs, OCPs, Es, and BPA ranged from 232.5 ng·g–1 to 5429.7 ng·g–1, 2047.2 ng·g–1 to 18051.5 ng·g–1, 4.5 ng·g–1 to 11.7 ng·g–1, 18.1 ng·g–1 to 105.2 ng·g–1, and 36.3 ng·g–1 to 69.6 ng·g–1, respectively. Among these five types of organic compounds, the concentration levels of PAHs and OCPs have decreased significantly in the last ten years, while those of PAEs and Es had an upward trend compared with the previous studies. BPA still remained at a moderately high level, as it was ten years ago. The risks of the PAEs in all of the sample sites, and fluoranthene, benzo[a]anthrene, and benzo[a]pyrene in the Wenyu River sediment, were relatively high. These results supplemented the database of toxic organics’ concentration levels in the sediments of Beijing rivers.
We studied the removal mechanism and affecting factors of Fe2+-based replacement–precipitation process for treating CuEDTA-containing wastewaters. Since Fe2+ was easily oxidized to Fe3+ in the presence of oxygen, the chelated copper was removed by the synergetic effect of Fe3+ replacement and NaOH precipitation. Our experiments showed that the copper removal efficiency was considerably dependant
on pH conditions of the solution and molar ratio of Fe2+/Cu2+. 相似文献
Abstract Science parks have developed greatly in the world, whereas empirical researches have showed that science parks based on linear model cannot guarantee the creation of innovation. Hi-tech innovation is derived from flow and management of information. The commercial and social interactions between in-parks and off-park firms and research institutions act as the key determinant for innovation. Industrial clustering is the rational choice for further developing Chinese science parks and solving some problems such as the lack of clear major industries and strong innovation sense, etc. 相似文献