Evaluation on the toxicity of ionic liquid mixture with antagonism and synergism to Vibrio qinghaiensis sp.-Q67

Ionic liquids (ILs) are a fascinating group of new chemicals with the potential to replace the classical volatile organic solvents, stimulating many applications in chemical industry. In case ILs are released to the environment, possible combined toxicity should be taken into account and it is, however, often neglected up to now. In this paper, therefore, the concentration-response curves (CRCs) of four groups of IL mixtures with various mixture ratios to Vibrio qinghaiensis sp.-Q67 were determined using the microplate toxicity analysis and were compared to the CRCs predicted by an additive reference model, the concentration addition (CA) or independent action (IA), to identify the toxicity interaction. It is showed that most of the IL mixture rays displayed the classical addition while the remaining rays exhibited antagonism or synergism. Moreover, it is found that the pEC₅₀ values of the mixture rays exhibiting antagonism or synergism are well correlated with the mixture ratio of a certain IL therein.     

Estimating the impact of seawater on the production of soil water-extractable organic carbon during coastal erosion

The production of water-extractable organic carbon (WEOC) during arctic coastal erosion and permafrost degradation may contribute significantly to C fluxes under warming conditions, but it remains difficult to quantify. A tundra soil collected near Barrow, AK, was selected to evaluate the effects of soil pretreatments (oven drying vs. freeze drying) as well as extraction solutions (pure water vs. seawater) on WEOC yields. Both oven drying and freeze drying significantly increased WEOC release compared with the original moist soil samples; dried samples released, on average, 18% more WEOC than did original moist samples. Similar results were observed for the production of low-molecular-weight dissolved organic C. However, extractable OC released from different soil horizons exhibited differences in specific UV absorption, suggesting differences in WEOC quality. Furthermore, extractable OC yields were significantly less in samples extracted with seawater compared with those extracted with pure water, likely due to the effects of major ions on extractable OC flocculation. Compared with samples from the active horizons, upper permafrost samples released more WEOC, suggesting that continuously frozen samples were more sensitive than samples that had experienced more drying-wetting cycles in nature. Specific UV absorption of seawater-extracted OC was significantly lower than that of OC extracted using pure water, suggesting more aromatic or humic substances were flocculated during seawater extraction. Our results suggest that overestimation of total terrestrial WEOC input to the Arctic Ocean during coastal erosion could occur if estimations were based on WEOC extracted from dried soil samples using pure water.     

电能表自动化检定系统监控功能的完善

针对电能表自动化检定系统工作过程中的异常现象,通过对其产生原因和影响因素的分析,提出了采用增加触点检测、温度监测、各工位信息实时集中监控的方法对监控功能进行完善。应用结果表明:改进方法实现了对各检定工位的实时监控,系统异常现象减少,合格率得到了提升,保证了检定系统的高效稳定运行。     

P(AM-DMDAAC-VAM)共聚物的合成及其絮凝性能

以丙烯酰胺(AM)、二甲基二烯丙基氯化铵(DMDAAC)、乙酸乙烯酯(VAM)为单体,采用水溶液自由基胶束共聚合法合成了疏水缔合阳离子型共聚物P(AM-DMDAAC-VAM),并对其进行了红外光谱和核磁共振氢谱表征。实验结果表明:在P(AM-DMDAAC-VAM)加入量为14 mg/L、絮凝温度为30~60℃、硅藻土悬浊液pH为8~11时,P(AM-DMDAAC-VAM)对硅藻土悬浊液的絮凝效果最好,上清液透光率高达97.5%。     

Nitrogen- vs. phosphorus-based dairy manure applications to field crops: nitrate and phosphorus leaching and soil phosphorus accumulation

Management of animal manures to provide nutrients for crop growth has generally been based on crop N needs. However, because manures have a lower N/P ratio than most harvested crops, N-based manure management often oversupplies the crop-soil system with P, which can be lost into the environment and contribute to eutrophication of water bodies. We examined the effects of N- vs. P-based manure applications on N and P uptake by alfalfa (Medicago sativa L.), corn (Zea mays L.) for silage, and orchardgrass (Dactylis glomerata L.), leaching below the root zone, and accumulation of P in soil. Treatments included N- and P-based manure rates, with no nutrient input controls and inorganically fertilized plots for comparison. Nitrate concentrations in leachate from inorganic fertilizer or manure treatments averaged 14 mg NO(3)-N L(-1), and did not differ by nutrient treatment. Average annual total P losses in leachate did not exceed 1 kg ha(-1). In the top 5 cm of soil in plots receiving the N-based manure treatment, soil test P increased by 47%, from 85 to 125 mg kg(-1). Nitrogen- and P-based manure applications did not differ in ability to supply nutrients for crop growth, or in losses of nitrate and total P in leachate. However, the N-based manure led to significantly greater accumulation of soil test P in the surface 5 cm of soil. Surface soil P accumulation has implications for increased risk of off-field P movement.     

Seasonal and spatial occurrence and distribution of atmospheric polycyclic aromatic hydrocarbons (PAHs) in rural and urban areas of the North Chinese Plain

Passive air sampling (PAS) was employed to study the occurrence of gaseous and particle-bound PAHs in the North Chinese Plain. The averaged concentrations of gaseous and particle-bound PAHs were 485 ± 209 ng/m³ and 267 ± 161 ng/m³, respectively. The PAHs concentrations at urban sites were generally higher than those at rural ones with ratios <1.5 in spring, summer and fall, but differences between them were not significant for the wintertime and annually averaged concentrations. This urban-rural distribution pattern was related to the PAHs emission sources. PAHs spatial variation can be partially (49%) explained by emission with a simple linear regression method. Both the gaseous and particle-bound PAHs were highest in winter and lowest in summer, with winter/summer ratios of 1.8 and 8, respectively. Emission strength was the most important factor for the seasonality.     

Bidens pilosa L. hyperaccumulating Cd with different species in soil and the role of EDTA on the hyperaccumulation

Environmental Science and Pollution Research - Investigating whether the same hyperaccumulator shows a high accumulation potential for different species of the same heavy metal in the soil has...     

Kinetic analysis of anaerobic phosphorus release during biological phosphorus removal process

Enhanced biological phosphorus removal (EBPR) is a commonly used and sustainable method for phosphorus removal from wastewater. Poly-β-hydroxybutyrate (PHB), polyphosphate, and glycogen are three kinds of intracellular storage polymers in phosphorus accumulation organisms. The variation of these polymers under different conditions has an apparent influence on anaerobic phosphorus release, which is very important for controlling the performance of EBPR. To obtain the mechanism and kinetic character of anaerobic phosphorus release, a series of batch experiments were performed using the excessively aerated sludge from the aerobic unit of the biological phosphorus removal system in this study. The results showed that the volatile suspended solid (VSS) had an increasing trend, while the mixed liquid suspended sludge (MLSS) and ashes were reduced during the anaerobic phosphorus release process. The interruption of anaerobic HAc-uptake and phosphorus-release occurs when the glycogen in the phosphorus-accumulating-organisms is exhausted. Under the condition of lower initial HAc-COD, HAc became the limiting factor after some time for anaerobic HAc uptake. Under the condition of higher initial HAc-COD, HAc uptake was stopped because of the depletion of glycogen in the microorganisms. The mean ratio of Δρ _P/Δρ _PHB, Δρ _GLY/Δρ _PHB, Δρ _P/ΔCOD, was 0.48, 0.50, 0.44, and 0.92, respectively, which was nearly the same as the theoretical value. The calibrated kinetic parameters of the HAc-uptake and phosphorus-release model were evaluated as follows: Q _HAc,max was 164 mg/(g · h), Q _P,max was 69.9 mg/(g · h), K _gly was 0.005, and KCOD was 3 mg/L. An apparently linear correlation was observed between the ratio of Δρ _P/ΔCOD and pH of the solution, and the equation between them was obtained in this study.     

Nitrogen export from an agriculture watershed in the Taihu Lake area, China

Temporal changes in nitrogen concentrations and stream discharge, as well as sediment and nitrogen losses from erosion plots with different land uses, were studied in an agricultural watershed in the Taihu Lake area in eastern China. The highest overland runoff loads and nitrogen losses were measured under the upland at a convergent footslope. Much higher runoff, sediment and nitrogen losses were observed under upland cropping and vegetable fields than that under chestnut orchard and bamboo forest. Sediment associated nitrogen losses accounted for 8-43.5% of total nitrogen export via overland runoff. N lost in dissolved inorganic nitrogen forms (NO(3-)-N + NH4+-N) accounted for less than 50% of total water associated nitrogen export. Agricultural practices and weather-driven fluctuation in discharge were main reasons for the temporal variations in nutrient losses via stream discharge. Significant correlation between the total nitrogen concentration and stream discharge load was observed. Simple regression models could give satisfactory results for prediction of the total nitrogen concentrations in stream water and can be used for better quantifying nitrogen losses from arable land. Nitrogen losses from the studied watershed via stream discharge during rice season in the year 2002 were estimated to be 10.5 kg N/ha using these simple models.     

白洋淀几种不同食性鱼类对六六六、DDT的富集

对白洋淀几种不同食性鱼体内六六六和ＤＤＴ残留量分析表明，草食性鱼体内农药残留量最少，六六六含量为５９．３μｇ／ｋｇ，ＤＤＴ含量为２９．６μｇ／ｋｇ；其次是杂食性鱼类，六六六含量为９０．４μｇ／ｋｇ，ＤＤＴ含量为１０８．５μｇ／ｋｇ；肉食性鱼体内农药残留量最高，六六六含量为１１０．７μｇ／ｋｇ，ＤＤＴ含量为１２４．４μｇ／ｋｇ。鱼体对ＤＤＴ的浓缩因子为３１１～１２４４，明显高于六六六的１７７～３６８。鱼体内ＢＨＣ４种异构体的残留顺序为δ＞α＞γ＞β，与其在水体中的比例α＞γ＞δ＞β略有不同。鱼体内ＤＤＴ主要以代谢物ｐ，ｐ＇－ＤＤＥ的形式存在，但个别样品中少量的ｐ，ｐ＇－ＤＤＤ及ｏ，ｐ＇－ＤＤＴ的检出，表明白洋淀水生生态系统最近受到ＤＤＴ的轻度污染。本项研果与１９７５～１９７７年检测结果进行比较；白洋淀鱼体内六六六残留量显著下降，下降率为１５．８％～７９．２％；ＤＤＴ残留量却明显增加（草食性鱼类除外），增加率约为４７．８％～９７．８％。