Temporal and spatial variations of contaminant removal, enzyme activities, and microbial community structure in a pilot horizontal subsurface flow constructed wetland purifying industrial runoff.

A pilot-scale horizontal subsurface flow constructed wetland (HSSFCW) was operated to purify industrial runoff containing polycyclic aromatic hydrocarbons (PAHs) in Guangzhou, China. Synthetic industrial runoff was fed into the HSSFCW with continuous flow at an average loading rate of 0.128 m(3)/(m(2)/day) for about 2 years. Pollutants such as chemical oxygen demand (COD), total phosphorus (TP), and phenanthrene were mainly removed in the front quarter of the HSSFCW, and in the vertical direction, the average removal rates of COD, TP, total nitrogen (TN), ammonia, and phenanthrene of the upper layer were 64.23, 71.16, 50.81, 65.38, and 92.47 %, which were 1.23, 2.08, 1.48, 1.72, and 1.17 times higher than those of the bottom, respectively. Correlations among pollutant removal, soil environmental indexes, enzyme activities, and soil microbial community structure were evaluated. Enzyme assays (dehydrogenase, catalase, nitrate reductase, and polyphenol oxidase) showed significant associations between enzyme activities and pollutant removal (p < 0.01 and p < 0.05). Soil microbial community structure was assessed with denaturing gradient gel electrophoresis (DGGE) fingerprinting method, and results demonstrated that bacterial communities remained relatively stable in different seasons. Proteobacteria and Bacteroidetes were found to be the dominant phyla of the bacteria communities, and three clones which might be related to the biodegradation of phenanthrene were also detected. Results of the present work would broaden the knowledge of the purification mechanism of contaminants in the constructed wetlands (CWs), and identification of the treatment performances and temporal and spatial variations of biological activities of subsurface flow constructed wetlands (SSFCWs) would help to improve the operations of CWs for surface water protection.

[Effect of constructed wetland on the purification of industrial zone rainfall runoff contaminated with phenanthrene].

According to the water characteristics of industrial rainfall runoff in the catchment of Tongsha Reservoir, Dongguan City, a subsurface-flow constructed wetland (SSFCW) was used to treat simulated rainfall and the spatial variation of removal efficiency of contaminants in the wetland bed was analyzed. The longitudinal and vertical variation of removal efficiency of COD, NH4(+) -N, TN, TP and phenanthrene were examined. Enzyme activity of polyphenol oxidase (PPO) and nitrate reductase (NR) along the wetland bed were analyzed as well, meanwhile, four biogeochemical indexes of the wetland system, including DO, pH, ORP and water temperature, were monitored and their influences on the removal efficiency of contaminants and enzyme activity were analyzed. Results showed that DO, pH, ORP, water temperature all presented a decreasing tendency along the wetland bed, and the removal of COD, TP and phenanthrene occurred mainly in the front quarter of the wetland system; in the vertical direction, DO and ORP in the upper wetland bed were significantly higher than those in the ground floor, suggesting that the horizontal subsurface system was in an anaerobic or anoxic condition. The removal rates of COD, TP, TN, NH4(+) -N and phenanthrene were 1.17-1.36, 2.04-2.11, 1.40-1.92, 1.37-2.30, and 1.07-1.36 times higher than those at the bottom, respectively. Therefore, the vertical variation of purification efficiency was more significant than the longitudinal variation. A significant positive correlation was determined between the enzyme activity of NR and the NO3(-) -N concentration, but the longitudinal variation in the enzyme activity of NR and PPO was not obvious.

[Effects of electroacupuncture on expression of calmodulin in the hippocampus of rats with cerebral ischemia-reperfusion injury].

OBJECTIVE: To investigate the protective effect of electroacupuncture (EA) on injured neurons and the signal transduction mechanism of calmodulin (CaM) in rats with cerebral ischemia-reperfusion injury (CIRI). METHODS: A total of 25 SD rats were randomly divided into a sham-operation group, a model group, an EA. group, a TFP group and an EA+TFP group. The rat model of middle cerebral artery occlusion (MCAO) was established by the modified Longa thread occlusion method. The EA group was treated with EA at "Dazhui" (GV 14) and "Baihui" (GV 20) for 30 minutes. The TFP group was treated with lumbar intrathecal injection of Trinuoperazine (TFP) at a dose of 40 microL/kg, the inhibitor of CaM. The EA + TFP group was treated with EA combined with TFP, and the sham-operation group and the model group without any treatment. The neurology deficit score was evaluated by the Julio's neuroethology score methods in all rats, and the expression of CaM in cerebral hippocampus tissue was detected with immunohistochemical method in different intervention condition. RESULTS: (1) In comparison with the model group of 6.90 +/- 1.66, the neuroethology score in the EA group of 14.50 +/- 1.08, the TFP group of 11.70 +/- 1.06 and the EA + TFP group of 14.30 +/- 1.06 were all significantly increased (all P < 0.01), while those still were all lower than the sham group of 17.60 +/- 0.52 (all P < 0.01), and the EA group was better than the TFP group (P < 0.01). (2) In comparison with the sham group of 0.080 +/- 0.045, the immune positive expression score of CaM protein in hippocampus in the model group of 1.680 +/- 0.268 was sig nificantly increased (P < 0.01). In comparison with the model group, the expression score of CaM protein in the EA group of 0.880 +/- 0.179, the TFP group of 0.720 +/- 0.179 and the EA + TFP group of 0.420 +/- 0.249 were all significantly reduced (all P < 0.01), and the expression score of CaM in the EA + TFP group was lower than that in the TFP group (P < 0.05). CONCLUSION: EA can reduce the injury of cerebral neurons induced by CIRI in rats and promote the recovery, which may be related to its effect in regulating CaM signaling pathway after the ischemia-reperfusion injury.