Respiration Index Determination: Dynamic And Static Approaches

Forty-five organic matrices of different types and origin were subjected to the test for the determination of biological stability by means of dynamic respirometric measurement (DRI) and static respirometric measurement (SRI). The results obtained from the comparison between the two indexes indicated that the SRI, compared with the DRI, underestimates the consumption of oxygen by the biomasses and consequently their rate of biological stability by a factor equal to 2. From the analysis of the data it is possible to define the biological stability as DRI<1000 mgO₂kg^?1VSh^?1. The DRI data were correlated with the temperatures of the biomasses showing a linear correlation (R²=0.81, p<0.01) only for stable matrices while for nonstable matrices no significant correlation is found.     

Assessment Of Tropical Grasses And Legumes For Phytoremediation Of Petroleum-Contaminated Soils

Phytoremediation is a promising technology for the clean-up of petroleum-contaminated soils, especially in the tropics where climatic conditions favour plant growth and microbial activity and where financial resources can be limited. The objective of this work was to identify tropical plant species from the eastern savannahs of Venezuela suitable for this technology. Three legumes (Calopogonium mucunoides, Centrosema brasilianum, Stylosanthes capitata) and three grasses (Brachiaria brizantha, Cyperus aggregatus, Eleusine indica) were tested for their ability to stimulate microbial degradation in soil contaminated with 5% (w/w) of a heavy crude oil. In greenhouse experiments, plant biomass production and oil dissipation (total oil and grease, and fraction composition) were analysed after 90 and 180 days incubation. Although previously tested on their tolerance to oil contamination, the legumes died within six to eight weeks. The grasses showed reduced biomass production under the influence of the contaminant. Relative growth rates were higher in contaminated soil indicating a delay in plant growth patterns and development. Soil planted with B. brizantha and C. aggregatus showed a significantly lower oil concentration than non-vegetated soil. Furthermore, a positive correlation between root biomass production and oil degradation was found. Concentration of saturated hydrocarbons was always lower in planted than in unplanted soil. B. brizantha also caused a considerable reduction of aromatics. Based on these results, B. brizantha is recommended for follow-up investigations which could further develop the application of phytoremediation of petroleum-contaminated soils in the tropics.     

黄土沟谷下蚀趋势评价的指标体系研究

均衡纵剖面是一切水道发育的最终形态 ,其标准形式是摆线。以实际沟谷与标准摆线间的差异为依据 ,初步建立了由摆线相关度和沟谷纵剖面几何形态参数两类指标构成的沟谷下蚀趋势评价指标体系 ,并以鸭儿沟为例进行了实际验证 ,结果较符合实际。     

畜禽粪便堆肥腐熟度评价指标体系研究

以牛粪和猪粪两种畜禽粪便分别与秸秆混合堆肥,全面考察了堆肥过程中与腐熟度有关的理化指标和生物指标变化。结果表明,在3个月的堆肥熟化试验考察期内,堆肥初期堆体升温迅速,50℃以上高温持续时间累计超过15d;物料pH值先升后降,60d后稳定在8.0左右;含水率和C/N持续下降,C/N60d后接近20;氨氮含量呈先升后降趋势,胡敏酸和富里酸比值则先降后升;Solvita腐熟等级、种子发芽势和根系建成指标不断升高,而作物生长指标则无显著变化。由腐熟度指标相关性分析表明,最能体现堆肥腐熟程度的Solvita腐熟等级与C/N、种子发芽势、根系建成指标呈高度相关,与含水率和腐殖酸呈低度相关。据此,结合常规温度指标建立了堆肥腐熟度评价指标体系,用于科学指导农牧业废弃物堆肥质量控制。     

城市河道生态护坡综合评价指标体系研究

以贵州省猫跳河流域为案例区,运用RUSLE模型对流域1973,1990,2007年土壤侵蚀空间格局进行了模拟。分析了该流域土壤侵蚀动态变化规律,为流域土壤侵蚀的有效防治提供了科学依据。结果表明,(1)流域下游以及上游西部溶蚀丘陵谷地土壤侵蚀较严重,土壤侵蚀量主要来源于强烈、极强烈及剧烈侵蚀区域,旱地和灌草地是流域发生土壤侵蚀的主要用地类型。(2)近30a来,流域土壤侵蚀经历了趋向严重—减轻的变化过程。1973—1990年低强度土壤侵蚀面积在减少,而高强度侵蚀面积在增加。1990—2007年,除了微度侵蚀面积大幅度增加外,其余侵蚀等级面积均在大幅度减少。6°～25°坡度带是发生土壤侵蚀的主要区域,也是水土流失防治及治理的重点区域。     

陕西省气候资源生产潜力与土地人口承载力的研究

该文系统分析了陕西省气候资源状况，估算了气候资源生产潜力，评价分析了气候资源利用状况。并以粮食人口承载力指数作为判别土地人口承载力的标准，对全省土地人口承载力进行预测。这将对该省的水土保持综合治理及国民经济持续发展具有宏观指导作用。     

高校图书馆硬实力与软实力评价指标体系研究

讨论了在信息时代,高校图书馆硬实力与软实力评价的重要性,明确了高校图书馆硬实力与软实力的内涵、特点及二者之间的关系。在分析影响软硬实力因素的基础上,建立了与时代发展相适应的高校图书馆硬实力与软实力评价指标体系。     

江苏省主要土壤的磷肥指数及适宜磷肥用量

以江苏省五种典型类型土壤为供试土壤,系统研究了不同类型土壤稻季的磷肥指数和磷临界值。研究结果表明,不同土壤类型的磷肥指数和磷临界值存在着较大的差异,其中磷肥指数表现为灰沙土>黄泥土>粉砂土>淤土>砂黄泥土,而磷临界值表现为淤土>黄泥土>砂黄泥土>灰沙土>粉砂土。并结合当地的特点,推荐了当地的适宜磷肥施用量。     

Effect Of The Sequential Application Of Liquid Organic Manure And Phosphorus On Maize Agronomic Traits And P Uptake In Some Tropical Soils

Improving phosphorus (P) fertility is challenging in tropical soils because of the fixation of P by soil components. The trial investigated the effect of the sequential application of poultry manure extract (tea) and P fertilizer on maize agronomy and P uptake, through screen house and field experiments. Results indicated that poultry manure tea is rich in nutrients but low in P and could be applied with phosphorus fertilizer to enhance P availability and reduce fixation. Application of P before manure tea produced taller maize plant on the field and the highest P uptake in the screen house and on the field. Manure tea also increased maize dry matter and grain yield. Combined application of poultry manure tea and P fertilizer had positive complementary and synergistic effects. It was concluded that manure tea enhances P availability and reduces P fixation by soil aluminum (Al) and iron (Fe) oxides irrespective of the sequence of application.     

土壤磷素吸持饱和度(DPS)评价土壤磷素流失风险研究

随着磷肥施用量增加,土壤磷素累积,由此所引起的土壤磷素流失越来越成为水体磷素的重要来源。本研究采集湖北省主要类型土壤,土壤风干过2 mm筛后,加入不同量的K2HPO4(0,30,40,60,100,160,200,240,300,400 mg P/kg土)进行室内培养,测定土壤M-3P、CaCl2-P和Fe、Al含量,计算土壤磷吸持饱和度(DPS),利用Split-line模型,预测不同土壤类型磷素流失风险。结果表明:土壤M-3P与Fe、Al含量间关系符合y=y0+axb方程(P0.05);土壤DPS与CaCl2-P含量关系,存在一个明显的突变点,即土壤磷素流失环境临界值,超过该值时,CaCl2-P含量急剧增加,但不同土壤类型其临界值差异较大,潮土、红壤和水稻土土壤磷素流失DPS临界值分别为18.8、12.9和13.3%,相对应的CaCl2-P含量分别为2.21、0.92、0.60 mg kg-1,根据以上临界值判断,红壤、水稻土极易发生流失。从区域角度考虑,土壤磷素流失DPS临界值为18.80%,该值能够给当地农业生产过程中的土壤磷素区域环境管理提供指导。     

赤红壤有效磷分级指标的研究

用盆栽试验方法得到玉米幼苗干物质相对积累量与赤红壤土壤有效磷含量的关系曲线可以用一元二次响应方程来拟合,土壤Olsen P含量的响应方程为:y=-0.4831x2+13.88x+2.664,决定系数为0.9555**;土壤Mehlich 3 P含量的响应方程为:y=-0.2621x2+9.4821x+18.891,决定系数为0.9400**。赤红壤区的土壤有效磷分级指标为:Olsen P,小于4.0 mg kg-1为"极低",4.0~6.8 mg kg-1为"低",6.8~10.5 mg kg-1为"中",大于10.5 mg kg-1为"高";Mehlich 3 P,小于3.6mg kg-1为"极低",3.6~7.5 mg kg-1为"低",7.5~12.0 mg kg-1为"中",大于12.0 mg kg-1为"高"。     

A Comparison of MER::LUX Whole Cell Biosensors And Moss, A Bioindicator, For Estimating Mercury Pollution

A sensor responsive to Hg²⁺ (pDL20) was constructed by fusing part of a narrow spectrum mer operon, including its regulatory elements, to promoterless lux genes. This was compared with another mer::lux fusion (pRB28) in order to estimate the available Hg in moss, a conventional bioindicator used for surveying Hg pollution in terrestrial environments. Hg(II) was measured as the relative luminescence unit (RLU) emitted by E. coli cells carrying either pRB28 or pDL20. The linearity ranges of standard curves were measured by spiking HgCl₂ at different nanomole levels in a phosphate buffered solution (PBS). The level of correlation between RLU and spiked HgCl₂ depended on the incubation time of E. coli cells: the correlation factors (R ²) of the regression lines were highly significant only after 150 min of incubation. pDL20 detected Hg(II) concentrations in the linear range between 0.05 nM and 0.5 nM and was approximately 27 times more sensitive than pRB28. The latter was less sensitive and showed a different range of linearity, from 20 nM to 200 nM. Measurements of bioavailable Hg were performed in buffered solutions leached from moss. Concentrations of Hg(II) were determined by external standard addition of HgCl₂. pDL20 was found to be more reliable than pRB28 in the estimation of very low concentrations of bioavailable Hg (II). Both sensors were unable to determine Hg(0) emitted by geothermal activities.     

Evaluating the performance of a soil compaction sensor

One of the most significant soil parameters affecting root growth is soil compaction. It is therefore important to be able to determine the presence of compacted layers, their depth, thickness and spatial location without the necessity of digging a large number of holes in the field with either a spade or backhoe. Previous investigations have identified soil compaction by different methods such as: using ground penetrating radar, acoustic systems, vertical and horizontal penetrometers and instrumented wings mounted on the faces of tines. Linking the output from these sensors to global positioning systems would give an indication of the spatial patent variation. The aim of this study was to evaluate the performance of a soil compaction profile sensor in both controlled laboratory and field conditions. The sensor consisted of a series of instrumented flaps; a flap is defined as the sensing element which comprises one half of a pointed leading edge to the leg of a tine to which strain gauges are placed on the rear face of the flap. Studies measured the effect of compaction on the changes in the soil resistance acting upon a flap face in a soil bin laboratory and under field conditions. The results indicated that the sensor was sensitive to differences in soil strength at different depths in soils. A technique was developed to identify the soil compaction resulting from different tyre inflation pressures and loads. The soil compaction profile sensor was tested on a number of fields in south‐eastern England to determine the changes in soil strength below the wheelings of a pea harvester operating at different tyre inflation pressures.     

Climatology of Discomfort Index and Air Quality Index in a Large Urban Mediterranean Agglomeration

The paper studies the climatology of the Discomfort Index (DI) and the Common Air Quality Index (CAQI) in a large Mediterranean urban center (Greater Thessaloniki Area), examines the relations between the indices and the climatic conditions in the study area and investigates the linkage between the Urban Heat Island (UHI) effect and the enhanced discomfort and poor air quality in the city center. Discomfort conditions are more enhanced during July and August. Atmospheric conditions when the population suffers discomfort and feels severe stress are found mainly in the summer season hours with total frequency that can be up to about 4% in a month. Throughout the year, air quality conditions are unhealthier in the stations of urban characterization. Very high daily CAQI values are more frequent during the cold period (about 14%) than during the warm period (1?C2%) of the year in the urban stations. Daily DI???24°C could be more associated to increased temperature than relative humidity and is strongly related to high and very high CAQI values. During summer, when daily CAQI is ??76, the feeling of discomfort is the most probable. Consequently, a strong synergy between discomfort and bad air quality exists in summertime. High and very high CAQI values and the discomfort feeling by the majority of the population are related to stagnant atmospheric conditions. During summer season, the poor air quality and the unfavorable comfort conditions for the majority of the population in the city center are associated with the greater frequency of a more intense UHI effect. The above phenomenon is more pronounced during nighttime than daytime.     

Evaluating the Sensitivity and Linearity of a Permanganate-Oxidizable Carbon Method

We evaluated a permanganate-oxidizable carbon (C) method using whole soil and physical fractions of soil from two field experiments and found that the method is a sensitive indicator of tillage and organic input effects on soil C. However, the recommended concentration (20 mM) and volume (20 ml) of permanganate reagent do not combine to provide a sufficient excess of permanganate to maintain linearity over the range of C levels commonly found in agricultural soils. This nonlinearity may be inconsequential when permanganate-oxidizable C is used as a field indicator of soil quality, but correction is desirable for research applications. We propose a correction method that provides reasonable correction for soils within a 3× range of permanganate-oxidizable C levels and improves sensitivity to changes in soil C resulting from differences in tillage and organic-matter additions.     

Evaluating taxonomic adjacency as a source of soil map uncertainty

Soil types or map units are considered to be taxonomically adjacent if they differ in only one criterion, defined by an arbitrary threshold value. By treating soil types as nodes of a graph and taxonomic adjacency as the graph edges connecting nodes, algebraic graph theory can be used to produce a measurement of the uncertainty in a soil map associated with arbitrary classification boundaries between soil types. The largest eigenvalue of the adjacency matrix of a graph, the spectral radius, is an indication of network complexity. A larger spectral radius indicates a more complex network, and a greater degree of uncertainty or potential error associated with taxonomic adjacency. Benchmark values of spectral radius for cases of no taxonomic adjacency, including a single pair of adjacent soils, a chain or cycle‐type graph structure and a fully connected graph, are established so that taxonomic adjacency indices based on the spectral radius can be established. Examples are shown from two contrasting USA soil landscapes in the Ouachita Mountains, Arkansas, and the coastal plain of North Carolina, using both US Soil Taxonomy and the world reference base. The taxonomic adjacency indices are also useful in assessing soil richness and pedodiversity, with smaller values indicating a greater likelihood that identified soils represent distinct entities.     

Replacement of a Peat-Lite Medium with Compost For Cauliflower Transplant Production

Seedlings of ‘Candid Charm’ cauliflower (Brassica oleracea L. Botrytis group) were grown in six different media comprised of varying proportions of a commercial peat-lite mix (PL) and a 50% yard trimmings 50% biosolids compost. A control of 100% PL was compared to treatments of PL:compost at 80%:20%, 60%:40%, 40%:60%, and 20%:80% respectively by volume, and 100% compost. The experiment was performed twice. Electrical conductivity of the medium increased with increasing compost additions, while the carbon:nitrogen ratio was greatly decreased. Increasing proportions of compost blended with PL inconsistently affected medium pH. Seedling emergence was delayed when compost comprised the majority of the medium, but stands were not reduced except with 100% compost. Decreases in seedling height and dry weight began to occur in the 60% PL, 40% compost treatment and were more pronounced with higher amounts of compost. Seedlings grown in 80% PL, 20% compost were similar to those grown in 100% PL with one exception: the compost blend resulted in an increased seedling N concentration. While we cannot conclude that a 20% replacement rate is ideal, the 80% PL, 20% compost medium was horticulturally acceptable as an alternative to 100% PL for cauliflower transplant production.     

Pesticide Screening in a Commercial Yard Waste And Biosolids Compost

The presence of pesticides in compost is of interest because of possible health, production and ecological risks. The presence of over 50 pesticides was assessed in raw yard waste, milled yard waste, and a finished compost (yard waste:biosolids) at a commercial compost facility in Florida. These pesticides were comprised of 38 herbicides, eight insecticides and two fungicides. Of the pesticides monitored for in this study, only atrazine, 4,4-DDE, alpha chlordane, gamma chlordane, and endosulfan I were detected, and were only present in raw yard wastes.     

Modelling climatic erosivity as a factor for soil erosion in Denmark: changes and temporal trends

Abstract. Daily measurements of precipitation and temperature at 82 locations in Denmark for periods of 10 to 43 years, were used for calculation of the impact energy and intensity of rain, climatic erosivity (hereafter called erosivity). The computed erosivity values were analysed for trends and variations in time and space. Analysis of 43 years of data from 6 locations showed a change in the annual distribution of intense (erosive) precipitation, with a tendency to bi-modality, increasing erosivity in September, and decreasing erosivity in August. Amounts of precipitation in autumn have generally increased, but the erosive power of rain has increased even more. The geographic location of high erosivity varied considerably from year to year. Using a simple crop model, the interaction between crop cover and erosivity was investigated. This suggested that changes in climate in combination with changes in cropping and management practice have increased risk of serious erosion over the period 1954 to 1996. We recommend that present and future cropping and management practices be evaluated for risk of adverse interaction with high erosivity events.