硫酸钙晶须对磷的静态吸附

以磷石膏废渣为原料制备硫酸钙晶须,考察了硫酸钙晶须对模拟含磷废水中磷的去除效果,分析了初始废水pH、初始磷质量浓度、硫酸钙晶须加入量对磷吸附效果的影响,研究了硫酸钙晶须对磷的吸附等温线,同时对吸附机理进行了探讨。实验结果表明：硫酸钙晶须在碱性条件下对磷的去除率较酸性条件下高,且初始废水pH为10时去除效果最佳;最佳硫酸钙晶须加入量为0.03 g/mg（以磷计）;在初始废水pH为10、初始磷质量浓度为50 mg/L、硫酸钙晶须加入量为1.5 g/L的条件下,于25 ℃下反应1 h,磷的去除率达到99.16%,上清液TP为0.419 mg/L;与Freundlich模型相比,Langmuir等温吸附模型更适合描述硫酸钙晶须对磷的吸附过程,采用该模型拟合得出25 ℃下磷的饱和吸附量为140.4 mg/g。     

Elevated water temperature reduces the acute toxicity of the widely used herbicide diuron to a green alga, Pseudokirchneriella subcapitata

In the actual environment, temperatures fluctuate drastically through season or global warming and are thought to affects risk of pollutants for aquatic biota; however, there is no report about the effect of water temperature on toxicity of widely used herbicide diuron to fresh water microalgae. The present research investigated inhibitory effect of diuron on growth and photosynthetic activity of a green alga Pseudokirchneriella subcapitata at five different temperatures (10, 15, 20, 25, and 30 °C) for 144 h of exposure. As a result, effective diuron concentrations at which a 50 % decrease in algal growth occurred was increased with increasing water temperature ranging from 9.2 to 20.1 μg L^–1 for 72 h and 9.4–28.5 μg L^–1 for 144 h. The photochemical efficiency of photosystem II (F _v/F _m ratio) was significantly reduced at all temperatures by diuron exposure at 32 μg L^–1 after 72 h. Inhibition rates was significantly increased with decreased water temperature (P?<?0.01). Intracellular H₂O₂ levels as an indicator of oxidative stress were also decreased with increasing temperature in both control and diuron treatment groups and were about 2.5 times higher in diuron treatment groups than that of controls (P?<?0.01). Our results suggest water temperatures may affect the toxicokinetics of diuron in freshwater and should therefore be considered in environmental risk assessment.     

微生物菌剂对好氧填埋垃圾稳定过程的影响

为加速好氧填埋场的稳定化进程,提出利用生物强化技术加速好氧填埋垃圾的生物降解,通过模拟实验,研究了微生物菌剂对填埋垃圾稳定过程的影响。结果表明:微生物菌剂降低了好氧填埋场的有机污染负荷,使渗滤液COD下降更加明显,整个填埋周期所产渗滤液的COD总量较对照组少20.20%;加速了含氮物质的生物转化,氨氮峰值出现较对照组提前6 d,经历峰值以后,氨氮快速下降,较对照组提前22 d达到国家生活垃圾填埋场污染控制标准(GB 16889-2008)所规定的渗滤液氨氮排放标准25 mg/L,并使整个填埋周期氨氮总量减少9.15%;微生物菌剂降低了渗滤液的产量,使整个填埋周期渗滤液累计产量减少8.29%;使垃圾中有机质降解加快并使其降解更加彻底,至实验结束时总有机质含量较对照组低8.82%,干重较对照组减少35.95%;沉降性能优于对照组,至填埋结束时较对照组沉降量提高6.35%。     

Effects of excited-state structures and properties on photochemical degradation of polybrominated diphenyl ethers: a TDDFT study

This study presents new insight into the photochemical degradation of polybrominated diphenyl ethers (PBDEs), and it provides details about the structures and properties of 27 PBDE congeners in the electronically excited state using the time-dependent density functional theory method. Each PBDE congener exhibited remarkably different geometries in the ground state and the excited state. The significant lengthening of C-Br bond in each PBDE congener was observed in the excited state for the first time by theoretical calculation, which is directly involved in the photochemistry reductive debromination of n-BDE to (n−1)-BDE. Generally, the lengthening of C-Br bonds cannot occur at the para position. Furthermore, the calculated results demonstrated that the photoreactivity of PBDEs increased with an increase of bromination degree. It was also found that the pattern of Br substituents had an effect upon the photoreactivity of PBDEs. These findings suggest that the information obtained in the excited state is crucial to the mechanism explanation of the photochemical degradation of PBDEs.     

酸碱改性对氧化铁脱硫剂脱硫性能影响的研究

通过酸碱改性制备了酸式和碱式2种不同表面性质的常温氧化铁脱硫剂,并采用FT-IR技术对其表面酸碱性质和净化硫化氢废气活性进行了研究.结果表明,表面酸碱件质不同的脱硫剂其脱硫反应行为也不同,在脱硫过程中硫化氢氧化生成的硫酸及亚硫酸会影响脱硫剂的表面酸碱性质,造成酸式脱硫剂的表面酸性更强,从而抑制了硫化氢分子在酸式脱硫剂表...     

ABR-好氧颗粒污泥处理黄连素废水的启动研究

实验研究了ABR-好氧颗粒污泥组合工艺处理黄连素制药废水的启动运行,通过分析发现,ABR装置在HRT为4 d,黄连素浓度为50 mg/L的运行方式下成功启动,反应器运行稳定后每个格室MLSS平均值分别为25 840、21 560、27 500和11 200 mg/L。以ABR出水为营养物,成功培养出粒径在2～10 mm,沉降速率为104～137 m/h,沉降性能优良的好氧颗粒污泥。该组合工艺在启动实验的末期,进水COD浓度为3 000～4 000 mg/L左右,出水COD浓度到达168.4～271mg/L,系统总的去除率保持在90%～95%之间,表明ABR-好氧颗粒污泥组合工艺能够有效地处理黄连素制药废水。     

Potential Economic Benefits of Adapting Agricultural Production Systems to Future Climate Change

Potential economic impacts of future climate change on crop enterprise net returns and annual net farm income (NFI) are evaluated for small and large representative farms in Flathead Valley in Northwest Montana. Crop enterprise net returns and NFI in an historical climate period (1960–2005) and future climate period (2006–2050) are compared when agricultural production systems (APSs) are adapted to future climate change. Climate conditions in the future climate period are based on the A1B, B1, and A2 CO₂ emission scenarios from the Intergovernmental Panel on Climate Change Fourth Assessment Report. Steps in the evaluation include: (1) specifying crop enterprises and APSs (i.e., combinations of crop enterprises) in consultation with locals producers; (2) simulating crop yields for two soils, crop prices, crop enterprises costs, and NFIs for APSs; (3) determining the dominant APS in the historical and future climate periods in terms of NFI; and (4) determining whether NFI for the dominant APS in the historical climate period is superior to NFI for the dominant APS in the future climate period. Crop yields are simulated using the Environmental/Policy Integrated Climate (EPIC) model and dominance comparisons for NFI are based on the stochastic efficiency with respect to a function (SERF) criterion. Probability distributions that best fit the EPIC-simulated crop yields are used to simulate 100 values for crop yields for the two soils in the historical and future climate periods. Best-fitting probability distributions for historical inflation-adjusted crop prices and specified triangular probability distributions for crop enterprise costs are used to simulate 100 values for crop prices and crop enterprise costs. Averaged over all crop enterprises, farm sizes, and soil types, simulated net return per ha averaged over all crop enterprises decreased 24% and simulated mean NFI for APSs decreased 57% between the historical and future climate periods. Although adapting APSs to future climate change is advantageous (i.e., NFI with adaptation is superior to NFI without adaptation based on SERF), in six of the nine cases in which adaptation is advantageous, NFI with adaptation in the future climate period is inferior to NFI in the historical climate period. Therefore, adaptation of APSs to future climate change in Flathead Valley is insufficient to offset the adverse impacts on NFI of such change.     

CuO/TiO2-H2O2可见光催化亚甲基蓝脱色效果及影响因素研究

以水解法制备的锐钛矿型TiO2为载体,制备了CuO/TiO2型光催化剂.以亚甲基蓝为对象,在可见光照射下研究了H2O3加入量、pH值和催化剂投加量对脱色效果的影响,同时与改性前的TiO2催化剂进行了脱色效果的对比.结果表明亚甲基蓝在碱性条件下能较好脱色,H2O2用量和CuO/TiO2催化剂投加量分别为每1 000 mL反应液各加入10 mL和0.1 g时脱色最好;另外,TiO2催化剂也在碱性条件下能较好脱色,H2O2用量和催化剂投加量分别为每1 000 mL反应液各加入12.5 mL和0.1 g时脱色最好.最优条件下对比实验表明,CuO/TiO2型催化剂在可见光照射下具有很高的催化活性,亚甲基蓝2 h脱色率达到88%,远好于改性前的TiO2和Degussa P25催化剂.     

PCDDs/PCDFs and PCBs in water samples from the Three Gorge Reservoir

The Three Gorge Reservoir (TGR) is the largest reservoir in China and its water quality is an important health concern, we have determined the concentrations of PCDDs/PCDFs and PCBs in the water samples collected at three seasons: August 2004, January 2005 and August 2005. The results showed that the average WHO-TEQ of total dioxins-like compounds (PCDDs/PCDFs+PCBs) was 0.06558 pg l(-1), ranged from 0.0008 to 0.32439 pg l(-1), which are much lower than other reported water sources. The main dioxins (PCDDs/PCDFs) are hepta- and octa-chlorinated dibenzo-p-dioxins (CDDs) and chlorinated dibenzofurans (CDFs). Since the levels of dioxins may change after the last water-store stage, the present study provides important data to compare the water quality in the TGR in the future.     

The impact of eutrophication on the biogeochemical cycling of mercury species in a reservoir: a case study from Hongfeng Reservoir, Guizhou, China

The mercury distribution and speciation in the water column were investigated from November 2003 to September 2004. The distribution and concentrations of total mercury (THg) and particulate mercury (PHg) showed that algae had a large capacity to bind mercury in late spring (e.g. in May). It is shown that dissolved gaseous mercury (DGM) concentrations may also be affected by algae activities. The MeHg profile in the water column at a highly eutrophied site in Hongfeng Reservoir demonstrated that most of the MeHg was produced in the hypolimnion, whereas the MeHg profile pattern at another site with less eutrophication indicated that MeHg in water was largely ascribed to release from sediment. In September, the outflow of the reservoir was enriched with MeHg, which was 5.5 times higher than that in the inflows. The discharge of MeHg-concentrated water from the anoxic hypolimnion in the reservoir may pose a risk to downstream fauna.