基于PSR模型的能源-生态复合区生态安全预警研究——以山西省忻州市为例

[目的]以山西省忻州市为例,探讨能源与生态复合区生态安全预警,为区域生态保护规划及区域高质量发展提供依据。[方法]基于PSR概念模型框架,从人口、资源、经济、环境、生态要素选取了21个指标建立了能源—生态复合区生态安全预警评价指标体系,采用熵值法确定权重,对山西省忻州市2000—2018年生态安全预警进行分析。[结果]①2018年忻州市14县综合预警值介于0.356 2～0.587 0之间,平均值为0.491 2,预警等级处于中警至轻警范围内。其中忻府区、定襄、五台、繁峙、静乐5县(区)警情为中警状态,其余7县(市)均为轻警状态,忻州市整体生态安全并不乐观,生态安全等级较低。②2000—2018年忻州市生态安全预警值呈波动缓慢上升趋势,警情为中警等级的县减少,轻警等级的县增加。[结论]研究区生态安全空间上呈现不均衡性,警情整体趋于改善,主要取决于系统压力中的经济、资源、环境压力趋缓。     

水稻田土壤硫酸盐还原活性的测定及其影响因子的研究

用显色比色测定法研究影响测定黄松稻田土壤硫酸盐还原活性的因素。结果表明水稻田土壤的含水量、培养温度和时间、硫酸盐的加入量和碳源物质对测定水稻田土壤硫酸盐还原活性有显著性影响。显色比色法测定水稻田土壤硫酸盐还原活性的最适条件为:土壤含水量(W/W％)在35％左右、培养时间为24h、培养温度为28℃、加入硫酸钠的最适量应在500μg/g干土左右。     

存在滑移时两平行刚性圆盘间二阶流体的挤压流动

两刚性圆盘间流体的挤压流动是一个基本的动力学模型,涉及到不少工程应用。二阶流体在剪切变形时会产生法向应力差,当存在滑移时,其压力分布及挤压力将会发生变化。该文以润滑理论为基础,采用小参数法研究了存在滑移时两刚性圆盘间二阶流体的挤压流动,导出了流体的速度和压力分布并进而求出挤压力的表达式。结果表明滑移导致压力分布和挤压力近似线性变化     

膨胀性岩质边坡加固方案的数值试验研究

膨胀性岩质边坡,由于其复杂性,加固方案不易确定。运用有限元方法对膨胀性岩体边坡的加固措施进行了较全面的数值试验研究,得出了坡顶超载与竖向位移、节理间距与坡顶变形及锚杆对坡顶变形影响的规律。该成果可为膨胀性岩质边坡加固方案的确定提供科学依据。     

贵溪冶炼厂周边农田土壤重金属污染特性及评价

在对贵溪冶炼厂周边区域的农田土壤及生产的稻谷进行采样调查和数据处理分析的基础上,对农田土壤重金属污染特性和现状进行了监测和初步评价,结果表明:农田土壤重金属污染可能来源于贵溪冶炼厂废水的排放及尾矿渣的堆放,与灌溉水源无关;用国家土壤环境质量二级标准进行评价可知,农田土壤重金属的综合污染指数较高,土壤污染已处于重度污染等级,单项重金属污染指数表明Cu、Cd的含量已严重超标,并处于重度污染等级,Zn、Pb和As的含量未构成污染;水泉村、竹山村与所生产的稻谷三者之间呈显著或极显著正相关,即农田生态系统呈复合污染的趋势。     

Effect of subcritical hydrophobicity in a sandy soil on water infiltration and mobile water content

Recent research shows that most soils are more or less water repellent. Already subcritical water repellency may cause incomplete soil wetting and preferential flow. Both processes potentially reduce the residence time of water and solutes in the vadose zone, resulting in an enhanced risk of groundwater contamination. The objective of the present paper is, therefore, to evaluate the impact of reduced soil wettability on the soil water infiltration rate and to investigate the tendency towards preferential flow with the analysis of the immobile water content in the infiltration zone. In november 2002, a field experiment was done in a coniferous forest, 30 km N of Hannover, Germany. Soil hydrophobicity was quantified by measuring the contact angles. The hydraulic conductivity of the podsolic sandy soil was measured depth‐dependent with a double‐ring tension infiltrometer in three soil horizons. To quantify possible preferential‐flow effects, a LiBr‐Tracer was added to the infiltrating water to evaluate the mobile water‐content fraction after infiltration. Additionally, infiltration rates of water were compared with infiltration rates of ethanol which were determined after water infiltration at the same locations. Results show that the actual water repellency of field‐moist soil was mainly subcritical (contact angle <90°). Water infiltration rates were reduced due to subcritical repellency by a factor of 3–170 compared with ethanol infiltration rates (exclusion of wetting effects). This spatially variable infiltration behavior was not clearly reflected neither by the small‐scale contact‐angle measurements nor by the analysis of the average immobile soil water content in the infiltration zone. We conclude that this specific infiltration behavior of water caused by small‐scale wettability effects may temporarily reduce the local connectivity of water‐flow pathways.     

Rapid, Micro-Methods to Estimate Plant Silicon Content by Dilute Hydrofluoric Acid Extraction and Spectrometric Molybdenum Method

By treating 0.5 g DW of a plant sample directly with 10 ml of a dilute hydrofluoric acid solution (HF solution, 1.5 M HF—0.6 M HCl), all the silica in plant (as much as 150 mg SiO₂) was dissolved within 1 h. After dilution of the extract with 40 mL of distilled water, the silica in the extract was measured by the spectrometric molybdenum yellow method. The molybdenum yellow method, in which silica in 0.1 mL of the diluted extract can be determined in 8 min, is well suited to rapid, micro-estimations of the silica content in plants. In the micro-modification, the size of the plant sample was reduced to 100 mg DW. The analytical procedure was simple, and the analytical time was less than 2 h. The method can save much labor and time, compared with the gravimetric analysis. The dissolution with HF solution and the molybdenum yellow method were also applied to the measurement of the content of silica separated by acid digestion of rice plants. Excellent agreement in the silica measurement of rice plants was confirmed among the direct extraction method, the gravimetric method and the digestion-separation-dissolution method. In the molybdenum yellow method, the addition of boric acid enabled to mask the interference of hydrofluoric acid, and the least amount of citric acid required for the elimination of phosphorus interference was proposed. In conclusion in this report, recommended methods for the rapid estimation of the silica content in rice plants were presented.     

针型电容法测量谷物含水率的研究

采用针型电容传感器和测量电路,并采取减小介质损耗的有效措施,研制了测量谷物含水率的针型电容法。实验结果表明,在谷物含水率与输出电压间具有良好的线性关系。该方法具有较高灵敏度、稳定性和良好的动态特性,完全可以满足谷物含水率的测量要求,为谷物含水率的准确、快速和在线测量提供了一种有效的方法。     

淤地坝坝体体积的计算

对于已确定的淤地坝坝址,坝体的纵断面（即沟道横断面）是一定的。根据实测的沟造横断面,以沟底最低点为坐标原点,沟道一侧的岸壁曲线可用幂函数形式表示之。利用这种幂函数关系,对于坝坡均一的坝体．在设定坝顶宽、坝高和上下游边坡之后,作者推导出沟道一侧坝体体积的计算公式;沟道两侧的坝体体积即为坝体总体积。对于非均一坝坡、设有马道的坝和坝体加高的体积,可将坝体横断面分割为由几个均一坝坡组成的坝体断面,分别计算其体积。这种计算方法的精度,取决于坝址横断面岸壁曲线回归方程与实际岸壁的符合程度。     

种植模式对苜蓿固氮和固氮产物转移的影响

田间小区试验研究了不同种植模式下苜蓿的共生固氮贡献,并利用~(15)N同位素示踪技术评估了苜蓿的％Ndfa和Ndfa,以及与之混作生长的牛尾草植株中来自苜蓿固氮产物的转移量。研究表明,豆科与禾本科牧草混作对发挥草地的优势有一定影响,混作条播在干草产量、全氮产量、％Ndfa和Ndfa等方面均优于间作与混作撒播模式,且高于单作苜蓿与牛尾草的平均值。用~(15)N同位素稀释法与~(15)N天然丰度法评估苜蓿的％Ndfa与Ndfa值时,无明显差异(P<0.05),前者还能准确测出混种牛尾革植株中的固氮产物转移量,后者则大大低估,甚至不能测出固氮产物转移。