天津市医疗废物处置规划及策略研究

以天津市医疗废物管理现状为研究对象，对处置方式进行深入探讨，分析目前分散处置和集中处置存在的缺陷，提出“区域集中处置”设想；并运用模糊决策模型理论，建立较完善的处置方式评价指标体系，应用模糊综合评价模型得出“区域集中处置”是最佳的医疗废物处置方式，同时提出了相应的区域集中处置策略。     

生物质废弃物催化裂解制备富氢燃气实验研究

由生物质废弃物催化裂解制取氢气是一种可再生的制氢方法，本研究采用2段加热管式反应器，前段装生物质，后段装催化剂，用以研究生物质催化裂解制取氢气的特性，并提出潜在氢产率的概念对生物质制氢的经济技术可行性进行深入的分析。测试的3种生物质废弃物为：松木粉、木质素和纤维素，测试温度为600～700℃。实验结果表明，加入催化剂后3种物料的产氢率从5．48～15．06g／kg增加到12．94～37．73g／kg；催化剂对潜在产氢率的影响较小，加入催化剂前后的变化范围为：36、25～98、86g／kg到37．40～116．98g／kg。生物质废弃物催化裂解产氢率与相同温度下空气-水蒸气气化的氢产率相当，实验结果证明，生物质废弃物催化裂解是一种有效的制氢方法。     

中空纤维微滤膜污染及阻力分析

选用0．1μm的PVDF中空纤维内压式微滤膜组件，在死端微滤工况下，研究了酵母（平均粒径5．3μm）和高岭土（平均粒径0．7μm）体系在浓度和压力变化时的污染机理及过滤阻力、膜渗透通量的变化规律性。通过恒压堵塞定律积分式的具体形式与实验数据的拟合及根据堵塞过滤定律计算的结果都表明：死端微滤时，酵母体系和高岭土体系均符合滤饼过滤机理。     

Using a process-based model to understand dynamics of Chinese agricultural and water technology development from 8000 bc to 1911 ad

Advancements in technology are inextricably bound to our society and the natural environment. However, how the development process of a technology system interacts with both remains unclear. We propose a process model to understand the complex dynamics among technology, society, and the environment via seven interactive elements: technologies, actors, receiving bodies, natural contexts, social contexts, temporal–spatial contexts, and outcomes. The model was applied to agricultural and water technology development in China from 8000 bc to 1911 ad. Our findings show that these elements did not play equally important roles in different periods of the development in ancient China, with social contexts most dominating during the earlier periods and both social and environmental concerns arising towards the later periods. The proposed model, by identifying the elements in the technology development that should be strengthened, can act as an analysis device to assist in reconfiguring a more sustainable socio-technological system.Electronic supplementary materialThe online version of this article (10.1007/s13280-020-01424-7) contains supplementary material, which is available to authorized users.     

Tolerance to,and avoidance of,hypoxia by the penaeid shrimp (Metapenaeus ensis)

Aquatic hypoxia caused by eutrophication may lead to mass mortality of valuable living resources such as fish and shrimp. However, there is little information on the hypoxic tolerance of penaeid shrimp, and whether they are able to avoid hypoxia. In laboratory experiments, LC50, LT50 and heart beats per minute were determined for juvenile Metapenaeus ensis at 0.5, 1.0, 2.0 and 6.0 mg O2 l(-1). The 8-h LC50, for DO was 0.77 mg O2 l(-1), while the LT50 at 0.5 mg O2 l(-1) was 399 min. Heart beat rate significantly declined when DO fell below 1.0 mg O2 l(-1). When confronted with a gradient of dissolved oxygen, M. ensis were able to avoid hypoxic areas and move to oxygenated water. M. ensis appeared to be sensitive to hypoxia, and their ability to detect and avoid hypoxia may enhance their survival in habitats where hypoxia may occur.     

Dechlorination of pentachloroethane by commercial Fe and ferruginous smectite

Short-term experiments were conducted to investigate the effect of a commercial Fe and an iron-bearing clay mineral, ferruginuous smectite (SWa-1), on the degradation of pentachloroethane (PCA). After 3 h of contact time, SWa-1 catalyzed PCA dehydrochlorination to tetrachloroethene (PCE, 65% conversion), whereas commercial Fe promoted PCA stepwise dechlorination via dehydrochlorination (approximately 40% conversion) and subsequent PCE hydrogenolysis to trichloroethene (TCE). The addition of unaltered SWa-1 to commercial Fe led to a complete inhibition on TCE production, whereas the addition of reduced SWa-1 barely resulted in a 30% decrease.     

Effects of metabolites of benzo(a)pyrene on unschedule DNA synthesis in BALB/3T3 cell line

In order to explore the damage from metabolites of benzo(a)pyrene on DNA of mammalian cells, the effects of four metabolites of benzo(a)pyrene (anti-BPDE, syn-BPDE, 3-OH-BP and 9-OH-BP) on synthesis of DNA and unschedule DNA synthesis (UDS) in BALB/3T3 cells were assayed, by methods of single-labeling and double-labeling. The results showed that all of the four agents were able to increase the synthesis of DNA, but only three of them (apart from syn-BPDE) induced UDS in BALB/3T3 cells. The above indicates that the metabolites of benzo(a)pyrene are able to damage DNA in BALB/3T3 cells, and that this effect may be relative to the sterical structure of metabolites of benzo(a)pyrene.     

Biodegradation of benzene, toluene; and other aromatic compounds by Pseudmonas sp. D8

Pseudmonas sp. D8 strain, which has the potential to utilize toluene as a sole carbon source, was isolated. At a concentration of 100 mg/l, this strain was found to efficiently degrade toluene and benzene (both individually and in mixture) in culture medium at 30°C and pH7. Following a two-hour lag phase, complete biodegradation of 100 mg/l toluene or benzene occurred within 6 to 8 hours. The addition of nitrate, phosphate, or sulfate at various concentrations were found to have significant influence on both toluene and benzene degradation. In addition, results show that the D8 strain has the ability to degrade monochlorophenols, nitrophenols, and phenol, but not aliphatic compounds. Inoculation of groundwater samples containing 100 mg/1 toluene or benzene with Pseudmonas sp. D8 resulted in rapid degradation within 24 33 hours.     

Arbuscular mycorrhizae enhance metal lead uptake and growth of host plants under a sand culture experiment

A sand culture experiment was conducted to investigate whether mycorrhizal colonization and mycorrhizal fungal vesicular numbers were influenced by metal lead, and whether mycorrhizae enhance host plants tolerance to metal lead. Metal lead was applied as Pb(NO3)2 in solution at three levels (0, 300 and 600 mg kg(-1) sand). Five mycorrhizal host plant species, Kummerowia striata (Thunb.) Schindl, Ixeris denticulate L., Lolium perenne L., Trifolium repens L. and Echinochloa crusgalli var. mitis were used to examine Pb-mycorrhizal interactions. The arbuscular mycorrhizal inoculum consisted of mixed spores of mycorrhizal fungal species directly isolated from orchard soil. Compared to the untreated control, both Pb concentrations reduced mycorrhizal colonization by 3.8-70.4%. Numbers of AM fungal vesicles increased by 13.2-51.5% in 300 mg Pb kg(-1) sand but decreased by 9.4-50.9% in 600 mg Pb kg(-1) sand. Mycorrhizae significantly enhanced Pb accumulation both in shoot by 10.2-85.5% and in root by 9.3-118.4%. Mycorrhizae also enhanced shoot biomass and shoot P concentration under both Pb concentrations. Root/shoot ratios of Pb concentration were higher in highly mycorrhizal plant species (K.striata, I. denticulate, and E. crusgalli var. mitis) than that in poorly mycorrhizal ones (L. perenne and T. repens,). Mycorrhizal inoculation increased the root/shoot ratio of Pb concentration of highly mycorrhizal plant species by 7.6-57.2% but did not affect the poorly mycorrhizal ones. In the treatments with 300 Pb mg kg(-1) sand, plant species with higher vesicular numbers tended to show higher root/shoot ratios of the Pb concentration. We suggest that under an elevated Pb condition, mycorrhizae could promote plant growth by increasing P uptake and mitigate Pb toxicity by sequestrating more Pb in roots.     

Investigation on the influence of methanol on adsorption and leaching of pesticides with soil column liquid chromatography

The effect of methanol of low concentration on adsorption and leaching of atrazine and tebuconazole was studied in this paper. The adsorption coefficients and the retardation factors (R^m) of pesticides on EUROSOIL 3# log-linearly decreased as volumetric fraction of methanol (f^c) was increased in the binary solvent mixtures of methanol and water. These data are consistent with solvophobic theory formerly outlined for describing the adsorption and transport of hydrophobic organic chemicals from mixed solvents. Nevertheless, the adsorption of these pesticides in soil–water system slightly increased when the soil was pre-washed with methanol in comparison with that pre-washed with water (pure water system). Furthermore, their adsorption coefficients were still higher in binary solvent systems with methanol of very low concentrations, i.e. f^c<0.03 for atrazine and f^c<0.01 for tebuconazole, than those in pure water system. The adsorption coefficients (logK^w) of atrazine and tebuconazole predicted by solvophobic theory were 0.5792 and 1.6525, respectively, and their experimental logK^w were 0.3701 and 1.6275 in pure water system. Obviously, the predicted logK^w of the two pesticides was higher than the experimental log K^w in pure water system. The predicted K^w and the retardation factor (R^w) in pure water system by solvophobic theory are thus possibly inaccurate.