Toxicity removal from contaminated water by constructed wetlands assessed using multiple biomarkers in human stem cell assays.

Constructed wetlands (CWs) have been developed rapidly as a sustainable water treatment technique. However, the capability of CWs for remediating the contaminated water based on toxicity assessment remains largely unknown. Four surface flow CWs and two integrated surface-subsurface flow CWs, from five cities in central and eastern region of China were evaluated, concerning the adverse effects of effluents and the toxicity reduction efficiency. Human bone marrow mesenchymal stem cells (hBMSCs) were employed as a human relevant in vitro model. The influent extractions caused cytotoxicity in a dose-dependent manner. The non-cytotoxic dilutions of the influents enhanced the genotoxicity marker γ-H2AX and reactive oxygen species levels. In addition, the influent repressed the osteogenic and neurogenic differentiation, and stimulated the adipogenic differentiation. Cytotoxicity of the contaminated water was reduced by 54 %-86 % after treatment with CWs. CWs were effective to remove part of the sub-lethal effects, with lower reduction than cytotoxicity. The integrated biomarker response (IBR) value of the effluents from the six CWs is lower than that of four secondary and one tertiary wastewater treatment plants. The IBR of the six CWs influents were in the range of 8.6-10.6, with a reduction of 15-50 % after the pollution restoration in CWs. The two integrated surface-subsurface flow CWs achieved higher IBR removal than the four surface flow CWs, possibly due to improved treatment effects by the combined systems. Cytotoxic and genotoxic effects of polar fractions in the CW effluents were stronger than the medium-polar and the non-polar fractions. Besides, PPARγ agonists present in the effluents played crucial roles and ERα agonists may make modest contributions. The present study enhances understanding of the role of CWs in achieving safe wastewater reclamation and provides evidence for further improving toxicity reduction in CWs performance.

[Ecological land use in three towns of eastern Beijing: a case study based on landscape security pattern analysis].

With the well-developed theory and methodology of landscape security pattern, and by the analysis of natural, biological, and cultural processes, it's possible to judge and plan the landscape security pattern of definite ecological process, i. e., to maintain the minimum ecological land use of this ecological process both in pattern and in area, which is of strategic significance. From the aspects of land coverage and spatial quality, this paper defined the ecological land use as the ecosystem (land unit) and its spatial position that have important significance in safeguarding critical ecological processes and providing critical ecosystem services. Taking three towns in eastern Beijing as an example, the ecological land use based on storm water management and biological conservation was analyzed. In the study area, the ecological land use at low, medium, and high security levels occupied 20.4%, 31.1%, and 48.6% of the total, respectively, indicating that the landscape security pattern approach based on critical ecological processes was an effective tool in the quantitative study of ecological land use, having important reference value for urban and land planning.