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291.
覆草旱作对晚稻田土壤氮素肥力的影响 总被引:2,自引:0,他引:2
在南方季节性丘陵干旱区通过田间定位试验研究了覆草旱作、裸地旱作和常规水作三种水稻栽培措施对双季稻轮作系统下晚稻田土壤氮素肥力的影响.结果表明,与裸地旱作和常规水作相比,覆草旱作处理显著提高晚稻移栽前和成熟期土壤碱解氮和矿质氮含量.在晚稻生育期,覆草旱作和裸地旱作稻田土壤无机氮以硝态氮为主.与裸地旱作相比,覆草旱作和常规水作处理显著提高晚稻成熟期土壤可矿化氮含量.与裸地旱作和常规水作相比,覆草旱作处理显著提高晚稻抽穗期和成熟期土壤微生物量氮含量和土壤脲酶活性. 相似文献
292.
Distribution,possible sources,and health risk assessment of SVOC pollution in small streams in Pearl River Delta,China 总被引:2,自引:0,他引:2
Hongwei Sun Taicheng An Guiying Li Meng Qiao Dongbin Wei 《Environmental science and pollution research international》2014,21(17):10083-10095
The pollution levels of typical semivolatile organic compounds (SVOCs) consisting of 15 polycyclic aromatic hydrocarbons (PAHs), 20 organic chlorinated pesticides (OCPs), and 15 phthalate esters (PAEs) were investigated in small rivers running through the flourishing cities in Pearl River Delta region, China. The concentrations of ∑15PAHs were 2.0–48 ng/L and 29–1.2?×?103 ng/g in the water and sediment samples, respectively. The ∑20OCPs were 6.6–57 ng/L and 9.3–6.0?×?102 ng/g in the water and sediment samples, respectively. The concentrations of ∑15PAEs were much higher both in the water and sediments. The partition process of the detected SVOCs between the water and sediment did not reach the equilibrium state at most of the sites when sampling. The combustion of petroleum products and coal was the major source of the detected PAHs. The OCPs were mainly historical residue, whereas the new inputs of dichlorodiphenyltrichloroethane (DDT), chlordane, and endosulfan were possible at several sites. The industrial and domestic sewage were the major source for the PAEs; storm water runoff accelerated the input of PAEs. No chronic risk of the SVOCs was identified by a health risk assessment through daily water consumption, except for the ∑20OCPs that might cause cancer at several sites. Nevertheless, the integrated health risk of the SVOCs should not be neglected and need intensive investigations. 相似文献
293.
Co-present Pb(II) accelerates the oxidation of organic contaminants by permanganate: Role of Pb(III)
Lei Dong Pin Xie Xin Zhang Junlian Qiao Dandan Rao Yuankui Sun Xiaohong Guan 《Frontiers of Environmental Science & Engineering》2022,16(8):109
294.
Chemical speciation and extractability of Zn,Cu and Cd in two contrasting biosolids-amended clay soils 总被引:13,自引:0,他引:13
An incubation experiment was conducted to study the chemical speciation and extractability of three heavy metals in two contrasting biosolids-amended clay soils. One was a paddy soil of pH 7.8 and the other was a red soil of pH 4.7 collected from a fallow field. Anaerobically digested biosolids were mixed with each of the two soils at three rates: 20, 40 and 60 g kg(-1) soil (DM basis), and unamended controls were also prepared. The biosolids-amended and control soils were incubated at 70% of water holding capacity at 25 degrees C for 50 days. Separate subsamples were extracted with three single extractants and a three-step sequential extraction procedure representing acetic acid (HOAc)-soluble, reducible and oxidisable fractions to investigate the extractability and speciation of the heavy metals. As would be expected, there were good relationships between biosolids application rate and metal concentrations in the biosolids-amended soils. The three heavy metals had different extractabilities and chemical speciation in the two biosolids-amended soils. Ethylene diamine tetraacetic acid extracted more Cu, Zn and Cd than did the other two single extractants. The oxidisable fraction was the major fraction for Cu in both biosolids-amended soils and the HOAc-soluble and reducible fractions accounted for most of the Zn. In contrast, Cd was present mainly in the reducible fraction. The results are discussed in relation to the mobility and bioavailability of the metals in polluted soils. 相似文献
295.
最近几年,市场上有一些白酒产品,利用“茅台”极高的市场信誉度和品牌价值,擅自以“茅台镇传世佳酿”、“茅台散酒”、“茅台某某酒”等相标榜,以致许多不了解情况的消费者被蒙蔽与误导,误认为是茅台酒的系列产品,与茅台酒是“一家人”。 相似文献
296.
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298.
PbO2电极的改性及其在难降解有机废水电化学处理中的应用 总被引:2,自引:0,他引:2
电化学方法处理难降解有机废水是一种很有前途的技术,其应用的关键是开发出高效、稳定、低成本的电极材料.PbO2电极在工业领域具有广泛的应用基础,具有较高的析氧电势和电催化活性,被认为在电化学处理难降解有机废水方面有重要的应用前景.本文对PbO2电极制备方法与改性以及在难降解有机废水电化学处理中应用的研究成果和最新进展进行了综述,并对该研究领域今后的发展趋势进行了分析. 相似文献
299.
改良型Carrousel氧化沟工艺生物脱氮除磷效果研究 总被引:13,自引:0,他引:13
为了提高改良型Carrousel氧化沟工艺污水处理厂的脱氮除磷效果,结合某污水处理厂3年的运行实践,讨论了该工艺的处理效果,生物脱氮除磷原理及影响出水效果的因素。分析表明将DO控制在0.3—0.7mg/L范围内,能够使出水中的TN浓度低于20mg/L;在氧化沟中发生的同步硝化反硝化反应(SND)对总氮的去除的贡献占总系统脱氮的66%;该系统剩余污泥的含磷率为3.0%,生物细胞中平均含磷量可达细胞干重的4.2%;总磷去除率与污泥龄具有很好的线性关系,加大污泥排放量可以提高除磷效果。 相似文献
300.
乔寿锁 《城市环境与城市生态》1993,6(3):31-36
本文从环境保护的科学技术支持系统分析入手,以环境科学研究对象和内容为核心,依据系统结构的内在规定性、环境科技的横断性、综合性和环境科学活动的组织规律,提出了支持系统的结构模型和科技队伍合理配置方案,可为环保科技结构调整、分流重组和能力建设所参考. 相似文献