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51.
以糖、淀粉、蛋白质、纤维素培养基及菌株增殖倍数、菌株性能等为筛选方法,从牛粪低温堆肥中筛选不同原料重要功能菌并组成功能菌剂;以不同类别原料菌及单菌株发酵实验对升温机制进行研究。结果表明,芽孢杆菌、假单胞菌、纤维单胞菌及小孢霉菌等为重要功能菌;菌剂起温快,升温效果好,48 h堆体即由低温进入中温,5 d达到高温,腐熟时间可缩短至约17~18 d;糖功能菌升温效果最为显著,淀粉及蛋白质功能菌次之,纤维素功能菌升温能力较弱;菌株利用各种原料能力越强,增殖速度越快,对升温作用越大。各菌株充分利用基质各成分,紧密协同和促进,是低温堆体发酵升温的主要作用机制。  相似文献   
52.
Abstract: Natural forests in southern China have been severely logged due to high human demand for timber, food, and fuels during the past century, but are recovering in the past decade. The objective of this study was to investigate how vegetation cover changes in composition and structure affected the water budgets of a 9.6‐km2 Dakeng watershed located in a humid subtropical mountainous region in southern China. We analyzed 27 years (i.e., 1967‐1993) of streamflow and climate data and associated vegetation cover change in the watershed. Land use/land cover census and Normalized Difference of Vegetation Index (NDVI) data derived from remote sensing were used to construct historic land cover change patterns. We found that over the period of record, annual streamflow (Q) and runoff/precipitation ratio did not change significantly, nor did the climatic variables, including air temperature, Hamon’s potential evapotranspiration (ET), pan evaporation, sunshine hours, and radiation. However, annual ET estimated as the differences between P and Q showed a statistically significant increasing trend. Overall, the NDVI of the watershed had a significant increasing trend in the peak spring growing season. This study concluded that watershed ecosystem ET increased as the vegetation cover shifted from low stock forests to shrub and grasslands that had higher ET rates. A conceptual model was developed for the study watershed to describe the vegetation cover‐streamflow relationships during a 50‐year time frame. This paper highlighted the importance of eco‐physiologically based studies in understanding transitory, nonstationary effects of deforestation or forestation on watershed water balances.  相似文献   
53.
54.
基于Berthollet反应示波极谱法测定水中微量氨   总被引:1,自引:0,他引:1  
在亚硝基铁氰化钾存在下,氨在氢氧化钠介质中与苯酚、次氯酸钠反应,其产物靛酚在滴汞电极上产生-灵敏的吸附波,NH3-N在0.003~0.22mg/L内,导数峰电流与其呈良好的线性关系。用于环境水中NH3-N的测定,其相对标准偏差小于3%,回收率为97%~105%,方法具有较好的选择性。  相似文献   
55.
报废汽车的回收拆解处理在我国已经逐渐兴起,但由于该产业尚处于发展初期,环保技术手段和可持续性发展意识还不够,因此在回收拆解过程中会产生大量的废水和其他污液。针对某汽车回收拆解厂的废水特性进行实验研究,形成“电荷凝集过滤一活性炭吸附”组合工艺,对报废汽车回收拆解企业的废水处理提供了一定的参考价值。  相似文献   
56.
Carbon monoxide (CO) in the surface sea waters is produced predominantly by photochemical processes, oxidized by micro-organisms and outgassed to the atmosphere. to assess carbon monoxide flux from the oceans to the atmosphere, the photochemical production and microbial oxidation of carbon monoxide in the oceanic mixed-layer was investigated during several oeanographic cruises and in the laboratory. the photoproduction rate of carbon monoxide was found to be well correlated to the concentration of dissolved organic carbon (DOC) in coastal and open ocean surface waters. Taking a global average carbon monoxide production rate of 10 ± 2 nmole litre-1 (mg DOC hr)-1 in the surface open ocean water, and 25 ± 7 nmole litre-1 (mg DOC hr)-1 in coastal sea water, at cloud-free summer solar noon, the photochemical production of carbon monoxide in the global oceans is estimated to be at a rate of 1200 ± 200 Tg CO y-1. the microbial carbon monoxide turnover time in the mixed-layer was observed to range from hours in a coastal estuary to 16 days in the Pacific along 1057deg; W in dark incubations. Natural sunlight can largely inhibit the microbial consumption of carbon monoxide in surface water. On a global scale, microbial consumption is responsible for the loss of less than 10% of photochemical produced carbon monoxide in the surface ocean. Field measurements have shown that the net transport of carbon monoxide from the euphotic zone to the underlying deeper ocean water is limited and that the overall life time in surface sea waters is less than 3-4 hours. When combined, these field measurements with the photoproduction and microbial consumption rates obtained, we estimate the oceanic flux to the atmosphere is about 1000 ± 200 Tg CO y-1, which represents the largest single source of atmospheric carbon monoxide.  相似文献   
57.
2008年汶川8.0级地震发生以来,极震区泥石流爆发频率有增无减且规模越来越大,破坏性越来越强,严重威胁灾区人民生命财产安全。对比采取现场勘查、遥感图像分析、历史资料对比分析等方法,分析了极震区泥石流动力特征受地形、地层、物源等因素的影响,特别是泥石流爆发过程中深侵蚀和溃决对泥石流动力特征的影响。针对四川安县高川乡流域泥石流沟的调查和分析,建立泥石流流量-冲刷模型,分析了常规地区泥石流峰值流量与极震区泥石流峰值流量差别,推导出极震区峰值流量及冲刷深度定量计算公式。通过实例分析,理论与实际具有较好的一致性,对极震区泥石流动力参数计算具有较好适用性和有效性。  相似文献   
58.
Understanding the effects of oxalic acid(OA) on the immobilization of Pb(Ⅱ) in contaminated soils by phosphate materials, has considerable benefits for risk assessment and remediation strategies for the soil. A series of phosphate amendments with/without oxalic acid were applied to two anthropogenic contaminated soils. We investigated the immobilization of Pb(Ⅱ) by KH2PO4, phosphate rock(PR), activated phosphate rock(APR) and synthetic hydroxyapatite(HAP) at different phosphate:Pb(P:Pb) molar ratios(0, 0.6, 2.0 and 4.0) in the presence/absence of 50 mmol oxalic acid/kg soil, respectively. The effects of treatments were evaluated using single extraction with deionized water or Ca Cl2, Community Bureau of Reference(BCR) sequential extraction and toxicity characteristic leaching procedure(TCLP)methods. Our results showed that the concentration of water extractable, exchangeable and TCLP-Pb all decreased with incubation time. The concentration of water-extractable Pb after120 days was reduced by 100% when soils were amended with APR, HAP and HAP + OA, and the TCLP-Pb was 5 mg/L for the red soil at P:Pb molar ratio 4.0. Water-soluble Pb could not be detected and the TCLP-Pb was 5 mg/L at all treatments applied to the yellow-brown soil. BCR results indicated that APR was most effective, although a slight enhancement of water-soluble phosphate was detected at the P:Pb molar ratio 4.0 at the beginning of incubation. Oxalic acid activated phosphates, and so mixing insoluble phosphates with oxalic acid may be a useful strategy to improve their effectiveness in reducing Pb bioavailability.  相似文献   
59.
本文提出一种水源地土地覆被分类及无人机遥感验证评价方法。采用面向对象分类方法对高空间分辨率卫星遥感影像进行土地覆被分类,基于无人机遥感影像,采用随机抽样方法获取多边形样本验证分类结果,建立混淆矩阵后评价分类精度,并采用国产卫星及无人机遥感数据开展示例研究,取得了很好的研究应用效果。  相似文献   
60.
在快速城镇化进程中,乡村凋敝对城乡协调和区域可持续发展构成严峻挑战。寻求乡村发展路径是落实乡村振兴战略的重要举措,也是迫在眉睫的核心任务。在厘清乡村聚落物质要素修补与非物质要素修复的聚落“双修”内涵基础上,针对乡村发展面临的系列难题,通过“生态”和“历史文化”资源整合、“人口”“土地”“产业”和“配套设施”的转移及建设,来探究根治“乡村病”的科学模式与振兴路径:对标双修、绿色发展以振兴乡村生态;六位一体、文化繁荣以振兴乡村文化;高效输出、对口回流以振兴乡村人才;横向联合、纵向推进以振兴乡村产业;三治融合、多元共建以振兴乡村组织。以祁东县沙井村规划实践为例,从人、生、文、地、产、设等六方面提出修复修补策略与措施,以达到修复乡村生态、培育乡村文化、恢复乡村社会朝气、振兴乡村产业经济、提升乡村人居环境的目的。  相似文献   
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