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871.
为提高细水雾对氨气的洗消效率,研究了两种复合型酸性添加剂MZ—1和MZ-2对细水雾的物理化学性质及洗消性能的影响。采用三维激光多普勒测速计和自适应相位多普勒速度计系统(LDV/APV)测量了含有MZ添加剂的细水雾和纯细水雾的雾滴粒径及速度的变化。通过小尺度模拟实验比较了含添加剂的细水雾和纯细水雾洗消氨气的效能高低。对实验结果的分析表明洗消剂中各成分之间的物理化学耦合作用提高了细水雾的洗消效率:表面活性剂组分降低了溶液的表面张力,减小了雾滴粒径,增大了细水雾与氨气的接触面积,而酸性电解质组分则可以与氨气发生化学反应,增强洗消剂的化学洗消作用。 相似文献
872.
农田杂草是阻碍农业生产的主要因素之一.明确农田杂草丰富度分布格局对农业生产管理具有重要意义.以青藏高原农田杂草为研究对象,利用物种分布模型探讨基于县域尺度的农田杂草物种丰富度分布格局及其未来(2050s)的变化,利用逐步回归筛选影响物种丰富度的环境因子,基于传统最小二乘法(OLS)和地理加权回归模型(GWR)分析环境因子对农田杂草物种丰富度的影响,并对两种分析方法进行比较.结果显示:(1)分布在青藏高原的农田主要杂草有51科284种,其中59种单子叶杂草、222种双子叶杂草、135种一年生杂草和149种多年生杂草.青藏高原农田杂草物种丰富度呈由西向东递增的变化规律,物种丰富度中心(丰富度值为167-194)主要集中在一江两河、河湟谷地和川西北等地区;(2)全球气候变化背景下,未来(2050s)青藏高原农田杂草物种丰富度整体呈由东南向西北方向增加的趋势,其中SSP1-2.6情境下最多增加43种,SSP5-8.5情境下最多增加49种;(3)GWR模型优于OLS,其结果表明青藏高原农田杂草物种丰富度的主要驱动因子是最冷季平均温、太阳辐射和最干月降水量,上述变量对杂草丰富度的影响存在明显的空间差异性,其中最冷季平均温由南向北逐渐从负向影响转变为正向影响.太阳辐射整体在青藏高原东部边缘等地区对农田杂草丰富度起正向的影响,在藏东南、青藏高原北部边缘等地区起负向的影响.最干月降水量对整个研究区域起负向影响,并表现出影响力由南向北逐步递增的趋势.上述结果表明青藏高原农田杂草物种丰富度调查不足,实际观测到的丰富度值明显低于当前气候下潜在的丰富度值,存在低估现象.当前气候背景下的农田杂草物种丰富度中心分布地区在未来仍是重点监管对象,且未来青藏高原部分地区作物可能面临新的杂草入侵风险.建议未来研究应注重于青藏高原粮食主产区农田杂草群落结构和功能调查、杂草和作物种间关系、耕地尺度上丰富度驱动因子分析等方面,为区域杂草管理和防治提供充分科学依据.(图6表2参53) 相似文献
873.
Chen Kang Liao Chenggang Li Ping Li Xingong Li Xianjun Zuo Yingfeng 《Journal of Polymers and the Environment》2022,30(6):2209-2221
Journal of Polymers and the Environment - Poor interfacial compatibility between wheat straw and polylactic acid (PLA) remains a problem that directly affects the overall performance of wheat... 相似文献
874.
Dissolved organic matter (DOM) plays a major role in ecological systems and influences the fate and transportation of many pollutants. Despite the significance of DOM, understanding of how environmental and anthropogenic factors influence its composition and characteristics is limited, especially in urban stormwater runoff. In this article, the chemical properties (pollutant loads, molecular weight, aromaticity, sources, and molecular composition) of DOM in stormwater extracted from three typical end-members (traffic, residential, and campus regions) were characterized by UV–visible (UV–vis) spectroscopy, excitation-emission matrix spectroscopy combined with parallel factor analysis (EEM-PARAFAC), and ultra-performance liquid chromatography quadrupole time-of-flight mass spectrometry (UPLC-Q-TOF-MS). There are three findings: (1) The basic properties of DOM in stormwater runoff varied obviously from three urban fields, and the effect of initial flush was also apparent. (2) The DOM in residential areas mainly came from autochthonous sources, while allochthonous sources primarily contributed to the DOM in traffic and campus areas. However, it was mainly composed of terrestrial humic-like components with CHO and CHON element composition and HULO and aliphatic formulas. (3) The parameters characterizing DOM were primarily related to terrestrial source and aromaticity, but their correlations varied. Through the combination of optical methods and UPLC-Q-TOF spectrometry, the optical and molecular characteristics of rainwater are effectively revealed, which may provide a solid foundation for the classification management of stormwater runoff in different urban regions. 相似文献
875.
876.
Long-term efficiency and stability of wetlands for treating wastewater of a lead/zinc mine and the concurrent ecosystem development 总被引:2,自引:0,他引:2
Yang B Lan CY Yang CS Liao WB Chang H Shu WS 《Environmental pollution (Barking, Essex : 1987)》2006,143(3):499-512
A constructed wetland system in Guangdong Province, South of China has been used for treating Pb/Zn mine discharge since 1985. The performance in the purification of the mine discharge and the concurrent ecosystem development within the system during the period of 1985-2000 has been studied. The untreated wastewater contained rather high concentrations of cadmium (Cd) (0.05 mg L(-1)), lead (Pb) (11.5 mg L(-1)), and zinc (Zn) (14.5 mg L(-1)), which greatly exceed the upper limits for industrial wastewater discharge in China. The constructed wetland system effectively removed Cd by 94.00%, Pb by 99.04%, Zn by 97.30%, and total suspended solids (TSS) by 98.95% from the mine discharge over a long period (over 16 years) leading to significant improvement in water quality; it was also found that there were no significantly annual or monthly variations in pH values, As, Cd, Hg, Pb, and Zn concentrations in water collected from the outlet of the wetland. Moreover, diversity and abundance of living organisms, including protozoan, higher plants, terrestrial animals, and birds, increased gradually. The 16-year monitoring results showed a reciprocal relationship, at a certain extent, between restoration of the wetland ecosystem, in other words, the maturity of the wetland, and the long-term efficiency and stability on purifying heavy metal-contaminated wastewater. 相似文献
877.
A large pentachlorophenol (PCP)-manufacturing plant located in southwestern Taiwan operated between 1965 and 1982. The present study was conducted to ascertain whether an increased body burden of dioxins existed in pregnant women living in an area of Tainan city contaminated by chemicals from this plant. Twenty-eight pregnant subjects, 21-39 years of age and residing in the study area between March and December of 2004 with a mean dwelling time of 6.07+/-6.11 years, were recruited. Concentrations of polychlorinated dibenzo-p-dioxins, dibenzofurans (PCDD/Fs), and dioxin-like polychlorinated biphenyls (PCBs) in serum of recruited residents were determined. Pregnant women residing in the study area >3 years had significantly higher PCDD (7.48 versus 5.13 pg-toxic equivalents [TEQ]/g-lipid) and dioxin-like PCB (6.70 versus 3.74 pg-TEQ/g-lipid) values as compared to those residing < or = 3 years. Furthermore, dioxin concentrations increased with increasing dwelling time. Statistical analyses performed according to demographic characteristics and socioeconomic and dietary habits revealed that total TEQ values were significantly associated with fish consumption and smoking status. Dioxin congeners with greater degrees of chlorine substitution (e.g., HpCDD/F and OCDD/F) partitioned to greater degrees in the subjects of this study as compared to subjects in the general Taiwanese population. The findings of this study strongly implicate the activity of the PCP manufacturing plant in the observed increase in dioxin body burden. Investigation of the health consequences of this increased body burden is recommended. 相似文献
878.
879.
880.