环境污染物导致氧化应激的关键信号通路及其检测方法

环境污染物能够以多种途径进入生物体内,在体内产生含氧自由基等活性氧物质,并通过多种信号通路及酶反应引起氧化应激,造成生物体内的脂质过氧化、蛋白质损伤、DNA表达改变、酶失活等,从而引发心血管疾病、风湿类疾病、感染及癌症等的发生。本文对环境污染物致氧化应激产生的原因、涉及的信号通路及酶反应、造成的危害,以及常见的基于细胞模型的氧化应激检测方法进行了综述,期望为评价环境污染物和检测氧化损伤提供参考。     

珠江三角洲4种淡水养殖鱼类重金属的残留及食用风险评价

为全面了解珠江三角洲淡水水产品中重金属污染现状,评估其生态风险与食用安全,于2014年8月至2015年8月采集罗非鱼、草鱼、乌鳢及鳜鱼主要养殖鱼类样品共计57份,采用原子荧光光谱仪(AFS),电感耦合等离子体质谱(ICP-MS)仪进行分析测定,并采用单因子污染指数(Pi)、重金属污染指数(MPI)、每周可耐受摄入量(PTWI)以及食入健康风险指标(Ri总)分别评估其污染程度、食用安全性与健康风险。结果表明,样品中Cr、Ni、Cu、Zn、As、Cd、Hg、Pb的含量范围分别为0.020~3.240,0.020~0.800,0.110~1.100,0.190~19.970,0.030~1.480,nd~0.606,0.003~0.118,0.040~0.803 mg·kg-1(湿重),Cr、As、Cd、Pb在水产品中超标率大小依次为As(7.0%),Pb(7.0%),Cd(5.3%),Cr(1.8%)。Pi结果表明,目前珠江三角洲养殖水域水产品中Cu与Zn残留处于正常范围内,Cr和Hg有少量样品为轻度污染,Pb、Cd与As存在重度污染样品,所占比例为2.86%、6.02%和5.74%。MPI结果显示不同水产品污染程度为乌鳢>鳜鱼>罗非鱼>草鱼,总体上各种水产品MPI依然处于较低的水平;食用安全性结果显示,目前成人每周摄入水产品是安全的,但乌鳢Cr,罗非鱼As含量较高分别达到PTWI的37.76%和19.51%,表明水产品中Cr、As残留可能存在一定的食用安全隐患。健康风险模型结果显示,所有样品均未超过国际辐射防护委员会(ICRP)的推荐的最大可接受水平(5×10-6a-1)。综合分析珠江三角洲淡水养殖主要水产品可知,其尚未出现明显的污染安全问题,但As与Cr等元素的潜在风险值得进一步关注。     

菲和镉单一及复合污染条件下在毛蚶体内的富集动力学研究

采用室内半静态双箱动力学模型实验,研究了菲和镉单一及复合污染条件下在毛蚶(Anadara subcrenata)体内的生物富集,通过对富集与释放过程中毛蚶体内菲和Cd的富集量进行非线性曲线拟合,获得了菲和Cd单一及复合污染条件下在毛蚶体内的吸收速率常数k1、释放速率常数k2、生物富集因子BCF、生物半衰期B1/2和平衡状态下最大富集量CA max等动力学参数。实验结果表明,菲和Cd在实验前期富集速率较高,8 d以后富集速率减缓,释放阶段与富集阶段相似。毛蚶对菲的BCF值为37.80,远大于Cd的BCF值13.12,且生物半衰期时间更长,菲更容易在生物体内富集。菲和Cd联合暴露条件下,在毛蚶体内的CA max和BCF值均大于单一作用,说明二者同时暴露时,毛蚶对菲和镉的吸收富集均有所增强。实验模型拟合度较好,输出值和实测值之间无显著性差异,拟合方程和拟合参数可信。     

PM_(2.5)对人肺癌细胞A549迁移、侵袭能力的增强作用

为探讨PM_(2.5)(particulate matter 2.5)对人肺癌细胞A549迁移、侵袭能力的影响并探讨相关机制,采用含有不同浓度PM_(2.5)的无血清及抗生素培养液对A549细胞培养72 h,利用MTT法检测A549细胞的增殖抑制率。根据MTT实验结果,选择适当的PM_(2.5)暴露浓度用于后续实验,以细胞划痕实验检测细胞迁移能力,transwell小室实验检测细胞迁移、侵袭能力,Western Blotting法检测细胞周期蛋白D1(cyclin D1)、转录因子snail和slug、基质金属蛋白酶-2(matrix metalloproteinase-2,MMP-2)、基质金属蛋白酶-9(matrix metalloproteinase-9,MMP-9)及胞核内β-链蛋白(β-catenin)的蛋白表达水平。结果显示:细胞划痕实验结果显示10μg·m L-1PM_(2.5)组A549细胞划痕创面愈合率为(46.34%±5.19%),与对照组比较显著增高(P<0.05);transwell小室法迁移和侵袭实验结果显示10μg·m L-1PM_(2.5)组穿膜细胞数平均为(165.67±6.62)个和(47.83±2.04)个,与对照组比较显著增多(P<0.05);Western Blotting实验结果显示PM_(2.5)(10μg·m L-1)可显著上调A549细胞cyclin D1、snail、slug、MMP-2、MMP-9和胞核内β-catenin蛋白表达水平。因此,PM_(2.5)可通过提高Wnt/β-catenin通路活性及其下游cyclin D1、snail、slug、MMP-2和MMP-9的蛋白表达而增强A549细胞的迁移、侵袭能力。     

Public participation in municipal solid waste source-separated collection in Guilin,China: status and influencing factors

Currently, China is facing critical problems regarding the management of municipal solid waste (MSW). The failure of existing pilot programs in implementing MSW source-separated collection highlights the need to analyze the factors significantly influencing public participation in this activity. To this end, a comprehensive analysis of MSW source-separated collection in Guilin, which is representative of wider areas located in inland China and with a GDP around the national average, was conducted. The research consisted of in-person interviews involving a questionnaire and theoretical analyses in terms of public perception, public awareness, public attitude, and willingness to pay. The analytical results identify the status of waste source-separated collection and influencing factors in implementation, and provides exercisable suggestions for decision makers in both China and more generally in industrializing countries to design promotion programs and education campaigns.     

Assessment of leaching behavior and human bioaccessibility of rare earth elements in typical hospital waste incineration ash in China

Leaching behavior and gastrointestinal bioaccessibility of rare earth elements (REEs) from hospital waste incineration (HWI) fly and bottom ash samples collected from Beijing and Nanjing Cities were assessed. In the same ash sample, the leaching concentrations of individual REEs determined by the Toxicity Characteristic Leaching Procedure (TCLP) were higher than those detected by the European standard protocol (EN-type test), thereby suggesting that the low pH value of leaching solution was an important factor influencing the leachability of REE. The REE bioaccessibility results, which were evaluated using the physiologically based extraction test (PBET), indicated that REEs were highly absorbed during gastric phase by dissolution; and subsequently precipitated and/or re-adsorbed in small intestinal phase. The relative amounts of the total REEs extracted by the TCLP method, EN-type test and PBET test were compared. In addition to the pH value of extraction solutions, the chelating role of REEs with organic ligands used in the PBET method was also an important parameter affecting REE adsorption in human body. Additionally, this study showed that REEs were extracted by these methods as concomitants of heavy metals and anions (NO₃ ^–, F^–, SO₄ ^2–, and Cl^–) from HWI ash, which probably caused the remarkably complex toxicity on human body by the exposure pathway.

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Improvement of sludge dewaterability with modified cinder via affecting EPS

The relationship between the improvement of sludge dewaterability and variation of organic matters has been studied in the process of sludge pre-conditioning with modified cinder, especially for extracellular polymeric substances (EPS) in the sludge. During the conditioning process, the decreases of total organic carbon (TOC) and soluble chemical oxygen demand (SCOD) were obviously in the supernatant especially for the acid modified cinder (ACMC), which could be attributed to the processes of adsorption and sweeping. The reduction of polysaccharide and protein in supernatant indicated that ACMC might adsorb EPS so that the tightly bound EPS (TB-EPS) decreased in sludge. In the case of ACMC addition with 24 g·L^–1, SRF of the sludge decreased from 7.85 × 10¹² m·kg^–1 to 2.06 × 10¹² m·kg^–1, and the filter cake moisture decreased from 85% to 60%. The reconstruction of “floc mass” was confirmed as the main sludge conditioning mechanism. ACMC promoted the dewatering performance through the charge neutralization and adsorption bridging with the negative EPS, and provided firm and dense structure for sludge floc as skeleton builder. The passages for water quick transmitting were built to avoid collapsing during the high-pressure process.

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Hexabromocyclododecanes in soils and plants from a plastic waste treatment area in North China: occurrence,diastereomer- and enantiomer-specific profiles,and metabolization

Plastic waste is a source of organic contaminants such as hexabromocyclododecanes (HBCDs). HBCDs have been found to cause developmental and reproductive toxicity; it is important to investigate the occurrence and metabolization of HBCDs in the soil environments with plastic waste contamination. This work analyzed HBCDs and their metabolites in soil and plant samples collected from Xinle and Dingzhou—the major plastic waste recycling centers in North China. Results showed that total HBCD concentrations in soils followed the order: plastic waste treatment site (11.0–624 ng/g) > roadside (2.96–85.4 ng/g) ≥ farmland (8.69–55.5 ng/g). HBCDs were detected in all the plant samples with total concentrations ranging from 3.47 to 23.4 ng/g. γ-HBCD was the dominant congener in soils, while α-HBCD was preferentially accumulated in plants. Compositions of HBCD isomers in soils and plants were significantly different (P < 0.05) among sampling sites and among plant species. HBCDs in farmland soil and all plant samples exhibited high enantio-selectivity based on the enantiomeric fractions (EFs). Furthermore, metabolites of pentabromocyclododecenes (PBCDEs) were frequently identified in soils, and mono-OH-HBCDs were the most common ones in plants. This study for the first time provides evidences of HBCD contamination in the soil-plant system caused by plastic waste, their stereo-selectivity, and metabolization behavior, improving our understanding of the environmental behavior and fate of HBCDs.     

神经网络在低压脱扣装置选择上的应用

低压脱扣装置应用于环境复杂的场合, 选型不当易使得电力事故频发,不利于电力系统的可靠运行。通过分析影响低压脱扣选择的因素,利用Back Propagation神经网络进行建模,提出了一种低压脱扣装置自动选择预测方法,结果表明:该方法在准确性与可重复性.上与传统方法相比具有较大优势,在工程应用中有一定的参考作用。     

周年磷肥旱季集中底施对玉-稻轮作磷肥效应的影响

春玉米-晚稻水旱轮作是近年来南方稻区种植制度变化下出现的新型两熟制模式。明确两季作物间磷肥的合理分配对玉-稻轮作作物产量与磷素利用效率的影响,对玉-稻轮作养分高效与高产协同实现,及丰富对水旱轮作前后季作物养分利用关系的认识具有理论意义。采用春玉米-水稻周年轮作田间试验,根据晚稻季磷肥前移至玉米季做底肥施用的比例及周年施磷量,设置7个磷肥施用处理,分别为两季作物均不施磷(P_0)、两季作物均按常规方法施磷(P_1)、1/3晚稻季磷肥前移(P_2)、2/3晚稻季磷肥前移(P_3)、全部晚稻季磷肥前移(P_4)、全部晚稻季磷肥前移且周年总施磷量减少15%(P_5)、全部晚稻季磷肥前移且周年总施磷量减少30%(P_6),分析了不同施磷处理作物产量、磷素吸收量及磷素利用效率的变化。与P_1相比,P_3与P_4处理显著提高了晚稻花后干物质的分配比例及晚稻产量,且其周年产量分别提高了4.87%和6.74%;P_5处理晚稻产量与P_1处理差异不显著,但P_6显著降低了晚稻产量。晚稻季磷肥前移施用明显促进了玉米及晚稻对磷素的吸收,显著降低了磷素的表观盈余量。与P_1处理相比,P_2、P_3、P_4处理两季作物周年土壤磷素依存率分别减少了11.63%、26.47%与22.08%。从磷肥利用效率看,P_4处理的磷肥周年累积回收效率、农学利用效率、偏生产力及磷肥产量贡献率均显著高于P_1处理,分别提高了102.46%、194.83%、6.73%与176.16%。与P_1处理相比,P_5处理周年磷肥产量贡献率及农学利用效率差异不显著,但分别提高了其磷肥回收效率与偏生产力32.56%和58.05%。玉米季施用的磷肥对晚稻有明显的后效作用,且比晚稻季施用磷肥具有更高的磷肥利用效率。所以在春玉米免耕复种晚稻时,可将晚稻季的磷肥全部前移至玉米季施用,并可减少15%周年施磷量。