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891.
利用土壤五氯酚(PCP)污染模拟实验,研究两种不同生态型蚯蚓(赤子爱胜蚓Eisenia foetida和壮尾环毛蚓Amynthas robustus E.Perrie)和堆肥固定化添加模式对漆酶降解土壤PCP的影响。在42 d培养期内,测试了不同处理下PCP质量分数、漆酶活性,以及土壤呼吸和微生物碳氮等微生物指标。结果表明:堆肥固定化漆酶降解土壤PCP的效果优于壳聚糖固定化漆酶和自由漆酶,主要原因是堆肥固定化漆酶能够有效地提高漆酶稳定性,减缓其活性下降速度。此外,堆肥还能提高土壤微生物的数量与活性,显著提升土壤漆酶的活性。添加两种生态型蚯蚓对漆酶活性影响不显著,但均可以显著提高土壤微生物的数量与活性,加速土壤中PCP的降解。壮尾环毛蚓对土壤微生物数量与活性的提升效果优于赤子爱胜蚓。 相似文献
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895.
基于遗传算法的支持向量机预测有机物自燃点的研究 总被引:1,自引:1,他引:0
根据定量构效关系(QSPR)原理,研究自燃点(AIT)与其分子结构间的内在定量关系。以265种有机化合物作为样本集,随机选择238种作为训练集,27种作为测试集,用遗传算法(GA)进行变量选择,分别建立多元线性回归(MLR)模型和支持向量机(SVM)模型研究有机物的自燃点与其分子结构间的关系。通过分析,发现造成模型预测效果不佳的原因是试验数据本身存在问题。通过对2个模型的比较,结果为GA-SVM模型明显优于GA-MLR模型,说明自燃点与其分子结构间具有很强的非线性关系。 相似文献
896.
采用间接阳极氧化处理活性染料模拟废水,以自制钛基IrO2电极为阳极,石墨为阴极,NaCl为支持电解质,考察了Ti/IrO2电极间接阳极氧化活性橙X - GN模拟废水的处理效果,研究了pH值、电压、电解时间及NaCl投加量对其降解效果的影响.结果表明,在pH值为3,电压为20V,NaCl投加量为2.5 g/L,室温条件下,电解30 min后该染料的脱色率达到100%,电解60min后COD去除率可达68%.在本试验条件下,染料通过电解产生的Cl2、ClO -、HClO等物质间接氧化降解.为探讨电化学氧化降解活性橙X - GN的过程,对该染料的降解过程进行UV - Vis光谱分析,初步探讨了该染料的降解规律.在电解过程中,染料的发色偶氮共轭体系首先被破坏,染料溶液的颜色逐渐褪去;经偶氮双键形成的共轭体系被破坏的同时,染料结构中的苯环结构、均三嗪结构以及萘环结构也遭到破坏,UV - Vis光谱中各基团的特征吸收峰基本消失;反应60 min后,UV - Vis光谱中已无明显吸收峰,表明该染料降解效果较好. 相似文献
897.
To reduce the leaching potential, to prevent groundwater contamination and to maintain the efficacy of a pesticide, natural polysaccharides have received increasing attention due to their biocompatibility and useful biological reactivity for controlled release formulations (CRFs) of pesticides. In this paper, the toxicities of the chiral herbicide dichlorprop (DCPP) and its complexes with chitosan molecules (DCPP-CS) and chitosan nanoparticles (DCPP-NP) to two different green algae were determined and compared. The inhibition rates of DCPP, DCPP-CS and DCPP-NP were determined at 24, 48, 72, 96, 120, 144, 168 h, and the results show that (S)-DCPP was more toxic to Chlorella vulgaris than (R)-DCPP, while the (R)-DCPP was more toxic to Scenedesmus obliquus than (S)-DCPP. The study also found that the chiral selectivity of DCPP to Chlorella vulgaris and Scenedesmus obliquus could be changed when DCPP was complexed with chitosan molecules (CS) or chitosan nanoparticles (NP). For Chlorella vulgaris, the order of inhibition was (R)-DCPP-CS > (S)-DCPP-CS and (R)-DCPP-NP > (S)-DCPP-NP; for Scenedesmus obliquus, the order was (S)-DCPP-CS > (R)-DCPP-CS and (S)-DCPP-NP > (R)-DCPP-NP. This phenomenon suggests that the enantioselective behaviors of chiral compounds might shift when interactions with other chiral receptors coexist in different biological environments. Additionally, chitosan molecules and chitosan nanoparticles also showed different toxicities, which could be ascribed to the difference in the physicochemical properties between CS and NP or the differences in the cell walls of the two fresh water green algae. 相似文献
898.
To determine the incidence of organochlorine pesticides (OCPs) in soil in a rapid urbanization region, soil samples from various land use types in Shenzhen were collected in winter, 2007. The concentration of dichlorodiphenyltrichloroethanes (DDTs) and hexachlorocyclohexanes (HCHs) ranged from non-detected to 149 ng g(-1) and 19 to 88 ng g(-1), respectively. The highest levels of OCPs were observed in soil from traffic and industry areas, reflecting that intensive human disturbance make the soil pollution accumulation more disperse. HCHs and DDTs profiles revealed that the sources were associated mainly with lindane and technical DDTs, respectively, while HCHs in the soil of Shenzhen might originate from both recent and historical sources. The loss of OCPs by soil erosion will enter surface runoff and impose impact on the water environment. Non-dietary exposure estimation indicates that children were the most sensitive group. The average daily exposure to OCPs for males was more serious than for females. Non-dietary exposure to DDTs and HCHs in residential blocks of Shenzhen were far below the acceptable daily intake recommended by the Food and Agriculture Organization/World Health Organization. 相似文献
899.
Our previous study indicated that the current level of polycyclic aromatic hydrocarbons (PAHs) in Shenzhen soil is in the low-end of world soil PAH pollution. In this study, the fate of PAHs in the soil of Shenzhen was investigated. The mass inventories of Σ(27)PAHs and Σ(15)PAHs (defined as the sum of the 27 or 15 PAH compounds sought) in topsoil of Shenzhen were ~204 and ~152 metric tons, respectively. Fate estimation of Σ(15)PAHs shows that air-soil gaseous exchange is the primary environmental process with ~10,076 kg/year diffusing from soil to air. Rain washing (~1131 kg/year from air to soil) is the most important input pathway followed by wet (~17 kg/year) and dry deposition (~8 kg/year) to soils in Shenzhen. The transport of Σ(15)PAHs by soil erosion is a crucial loss process for soil PAHs in Shenzhen (1918 kg/year for water runoff and 657 kg/year for solid runoff from soil). Moreover, degradation is not ignorable at present (95 kg/year). Comparison of inventory and residue (defined as Σ(15)PAHs left in topsoils after all environmental loss processes) suggested that input and loss of high molecular weight PAHs for Shenzhen's soil reached apparent equilibrium. Soil PAH pollution in Shenzhen will stay in a quasi-steady state for a long period and the natural environmental processes can not significantly reduce the pollution. 相似文献
900.
为调查四川省地表水体中放射性物质铀(U)的含量,评价居民摄入地表水体中U导致的健康风险,在四川省主要地表水系中共设置23个监测断面,于2016—2021年检测了U的放射性水平,并根据健康风险评价模型对居民的健康风险进行评估。结果表明:四川省地表水体中U的质量浓度为0.16~3.6 μg/L,参照《生活饮用水卫生标准》(GB 5749—2022),均合格;不同年份、不同地表水体中U的放射性水平间的差异均无统计学意义(P>0.05);不同水期U的放射性水平间的差异有统计学意义(P<0.05)。各年龄组通过饮水、水体浸没途径摄入U所致总年均待积有效剂量均<0.1mSv;对各年龄段居民的总致癌风险为4.18×10-9 ~2.24×10-8 ,均低于世界卫生组织(WHO)和国际放射防护委员会(ICRP)发布的最严格控制限值。全省主要地表水体中U对各年龄组都是安全的。 相似文献