Dynamics of cyanobacterial bloom formation during short-term hydrodynamic fluctuation in a large shallow, eutrophic, and wind-exposed Lake Taihu, China

Short-term hydrodynamic fluctuations caused by extreme weather events are expected to increase worldwide because of global climate change, and such fluctuations can strongly influence cyanobacterial blooms. In this study, the cyanobacterial bloom disappearance and reappearance in Lake Taihu, China, in response to short-term hydrodynamic fluctuations, was investigated by field sampling, long-term ecological records, high-frequency sensors and MODIS satellite images. The horizontal drift caused by the dominant easterly wind during the phytoplankton growth season was mainly responsible for cyanobacterial biomass accumulation in the western and northern regions of the lake and subsequent bloom formation over relatively long time scales. The cyanobacterial bloom changed slowly under calm or gentle wind conditions. In contrast, the short-term bloom events within a day were mainly caused by entrainment and disentrainment of cyanobacterial colonies by wind-induced hydrodynamics. Observation of a westerly event in Lake Taihu revealed that when the 30 min mean wind speed (flow speed) exceeded the threshold value of 6 m/s (5.7 cm/s), cyanobacteria in colonies were entrained by the wind-induced hydrodynamics. Subsequently, the vertical migration of cyanobacterial colonies was controlled by hydrodynamics, resulting in thorough mixing of algal biomass throughout the water depth and the eventual disappearance of surface blooms. Moreover, the intense mixing can also increase the chance for forming larger and more cyanobacterial colonies, namely, aggregation. Subsequently, when the hydrodynamics became weak, the cyanobacterial colonies continuously float upward without effective buoyancy regulation, and cause cyanobacterial bloom explosive expansion after the westerly. Furthermore, the results of this study indicate that the strong wind happening frequently during April and October can be an important cause of the formation and expansion of cyanobacterial blooms in Lake Taihu.     

潮汐流-潜流组合人工湿地污水净化效率

构建了潮汐流-潜流组合和潜流-潮汐流组合人工湿地对污水进行处理,分别研究2种组合人工湿地对污水的净化效果。结果表明,在平均进水COD浓度为214．28mg／L、NH4＋-N浓度为10．57mg／L、PO34--P浓度为5．44mg／L、TN浓度为10．25mg／L,水力负荷为o．2m3／（m2·d）的条件下,潮汐流-潜流组合人工湿地对COD、PO34--P的去除率分别为58．28％和46．99％,与潜流-潮汐流组合人工湿地处理效果相近;对NH4＋-N、TN,潮汐流-潜流组合人工湿地的去除率分别为69．93％和71．03％,比潜流-潮汐流组合人工湿地分别高15％和33％。潮汐流-潜流人工湿地的组合,在系统内实现了硝化-反硝化的组合,强化了系统对TN的净化效果,其对TN的净化效果比-般的潜流和表面流人工湿地组合提高20％～30％。总体上,潮汐流-潜流组合人工湿地具有更好的净化效果。     

丝瓜瓤固定化脱色菌Enterobactor sp.S8 对活性黑5的脱色

利用植物载体丝瓜瓤对肠杆菌(Enterobactor sp.S8)进行固定,并对活性黑5进行脱色研究.探讨了固定化菌体的菌龄、菌量、pH、温度对染料脱色的影响.研究了该固定化菌体的重复利用和动力学实验.结果表明,最佳脱色条件为:菌龄3d、接菌量2％、温度30℃、pH 6.0.该固定化菌体对不同初始浓度活性黑5的脱色符合二级反应动力学方程.经9次重复利用后的该固定化菌体,其脱色率仍达76.8％.在优化实验条件下,根据降解3d前后的紫外-可见光谱图分析可知,活性黑5并非完全被降解为CO2和H2O,而是生成一些小分子有机中间体.     

复合赤泥在高浓度含磷废水处理中的应用

赤泥与石灰粉（CaO和Ca（OH）₂）按不同比例混合制成复合赤泥,通过投加实验考察了复合赤泥的除磷效果。结果证明,对于磷酸盐浓度为45 000 mg/L左右（以P计）的酸性工业废水,复合赤泥（赤泥与Ca（OH）₂按质量比1：1混合）投加量为240 g/L,去除率为99.97%;对于10 mg/L左右的含磷废水,赤泥的最佳投加浓度为15 g/L,上清液磷浓度可降至0.30 mg/L,出水低于0.5 mg/L的排放标准。根据以上研究结果,提出了对高浓度酸性磷酸盐废水的处理宜采用复合赤泥再加原状赤泥的二级处理方法。     

中试螺旋式自循环厌氧反应器处理安乃近制药废水的稳定性能简

以制药废水实验了50 m³螺旋式厌氧反应器（SPAC反应器）的稳定性。采用Augmented Dickey-Fuller（ADF）单位根检验表明,螺旋式反应器具有良好的启动和运行稳定性。负荷冲击实验显示,SPAC反应器具有较好的耐浓度冲击能力和耐水力冲击能力,所能耐受的最大浓度冲击强度大于60 000 （mg·h）/L（进水浓度提升2倍）,所能耐受的最大水力冲击强度为300（m³·h）/d（进水流量提升50%）。SPAC反应器还具备受扰恢复能力。在反应液pH低于5.74,出水浓度、COD去除率和容积COD去除速率（VRR）分别为3 500 mg/L、22.30%和2.52 kg/（m³·d）的工况下,经过30 d恢复,出水浓度、COD去除率和VRR的恢复程度达到80%~90%。     

厌氧污泥对间二氯苯的吸附性能简

为了研究灭活厌氧污泥和活性厌氧污泥对间二氯苯 （m-DCB）的吸附,考察了吸附平衡时间、吸附动力学、吸附等温线、吸附热力学、污泥投加量和pH对吸附m-DCB的影响。结果表明,2种污泥对m-DCB的吸附在1 h内达到平衡。应用伪一级、伪二级反应动力学对实验数据进行验证,表明厌氧污泥吸附m-DCB更符合伪二级反应动力学模型。2种污泥对m-DCB的吸附都可以用Langmuir和Freundlich吸附模型拟合,但Langmuir吸附模型的拟合结果要好于Freundlich模型,且活性厌氧污泥的吸附性能显著高于灭活厌氧污泥。从吸附热力学上看,该吸附为放热反应,低温有利于吸附反应的进行。pH值对2种污泥吸附m-DCB的影响很小。     

Effect of Tween 80 and beta-cyclodextrin on degradation of decabromodiphenyl ether (BDE-209) by White rot fungi

The environmental safety of decabromodiphenyl ether (BDE-209), a widely used flame retardant, has been the topic of controversial discussions during the past several years. Degradation of BDE-209 into lower brominated diphenyl ether congeners, exhibiting a higher bioaccumulation potential, has been a critical issue. White rot fungi are known to degrade a wide variety of recalcitrant pollutants. In this work, white rot fungi were used to degrade BDE-209 in liquid culture medium, and the effects of Tween 80 and beta-cyclodextrin on BDE-209 degradation by white rot fungi were evaluated. On the basis of these results, it appears that BDE-209 could be degraded by white rot fungi, and Tween 80 and beta-cyclodextrin can both increase the biodegradation. The best result in Tween 80 experiments was obtained at a Tween 80 concentration of 500mgl(-1) within 10d, which showed 96.5% (w/w) BDE-209 transformed. Tween 80 at a high concentration will restrain the fungal growth and the degradation of BDE-209. However, beta-cyclodextrin had positive effects both on the BDE-209 degradation and the fungal growth.     

浙江某水库大坝渗流安全综合分析

对浙江省某水库大坝的测压管观测资料进行了分析,建立了用来预报测点水位并能反映大坝实际渗流性态的统计模型。在此基础上结合观测资料采用有限元方法反演了坝体、坝基各分区的渗透系数,预测未来高水位时大坝的渗流性态,并建立了物理概念明确、预报效果较好的渗压确定性模型。     

Spatial distribution of inorganic nitrogen contents of marsh soils in a river floodplain with different flood frequencies from soil-defrozen period

Contents of inorganic nitrogen (NH4(+)-N and NO3(-)-N) in soil profiles were measured in five typical zones ( including permanently flooded floodplain(B), 1-year floodplain (O), 5-year floodplain (F),10-year floodplain (T), and 100-year floodplain (H) )from Huolin River floodplain in Erbaifangzi, Jilin Province of China, in the soil-defrosted period (Mayof 1999). Contour maps and profile maps were constructed to describe the spatial distributions of NH4(+)-N and NO3(-)-N) in order to identify the influences of flood frequencies on them. Results showed that NH4(+)-N generally increased with depth in soil profiles from the five areas, but NH4(+)-N contents in T or H areas significantly differed from those in other areas. For NO3(-)-N, with the exception that there was a significant cumulative peak (6.77 +/- 0.08 mg kg(-1)) at 15-cm depth (10-20 cm) in B area, no significant difference was observed between NO3(-)-N contents in soil profiles from the other four areas. The horizontal distributions of NH4(+)-N and NO3(-)-N in top soils (0-10 cm) were different in the five areas,which were greatly influenced by flood frequencies. The highest content of NH4(+)-N or NO3(-)-N did not appear in B area but in the floodplain with certain flood frequency. For example, NH4(+)-N content (16.81 mg kg-(1)) in 5-year floodplain wetland was highest, and the highest content of NO3(-)-N(1.69 mg kg(-1)) appeared in 1-year floodplain wetland. In addition, NH4(+)-N contents were significantly correlated with soil pH, and NO3(-)-N contents had significant correlation with inorganic carbon, but there were no significant correlations between inorganic nitrogen and other selected soil properties.