Simple Spatial Modeling Tool for Prioritizing Prescribed Burning Activities at the Landscape Scale

Abstract:   Resources for prescribed fire are frequently insufficient to manage public lands for all conservation and resource management objectives, necessitating prioritization of the application of fire across the landscape within any given year. Defining tradeoffs when applying prescribed fire to large landscapes is problematic not only because of the complexity of weighing competing management objectives at the landscape scale, but also because of the difficult nature of independently applying need-to-burn criteria to large areas. We present a case study of a simple modeling process implemented at Eglin Air Force Base in the Florida Panhandle (U.S.A.) to prioritize the application of prescribed fire. In a workshop setting, managers and biologists identified key conservation criteria and landscape management objectives that drive the application of prescribed fire. Remote sensing and other spatial data were developed to directly or indirectly represent all these criteria. Using geographic information system software, managers and biologists weighted each criterion according to its relative contribution to overall burn prioritization, and individual values for the criterion were scored according to how they influence the need to burn. Subsequently, this process has been validated and modified through ecological monitoring. This modeling process has also been applied to the 77,400-ha Blackwater River State Forest, public land adjacent to Eglin Air Force Base, demonstrating its applicability to lands with varying management priorities. The advantages of this model-based approach for prioritizing prescribed fire include the reliance on accessible, inexpensive software, the development of spatially explicit management objectives, the ease of transferability, and clearly stated assumptions about management that may be tested and reviewed through monitoring and public comment.     

探究不同金属离子对电化学氧化去除水体中4-CP的影响

文章为探究金属离子(亚铁离子、铁离子、二价铜离子、二价锰离子)对电化学氧化降解废水中4-CP的影响。采用自制的圆形电化学反应器,通过添加不同含量的金属离子来探究对4-CP去除效果的影响。试验的研究表明,亚铁离子具有较好的催化强化效果,平均催化效率可达24%,且Fe(Ⅱ)最适宜投加量为1.5mmol/L,催化效率可提高31.5%。另外其他三种金属离子均存在不同程度的抑制,其中抑制效果由强到弱为Mn(Ⅱ)>Fe(Ⅲ)>Cu(Ⅱ),且当Mn(Ⅱ)投加量为3.0 mmol/L时,完全抑制4-CP的电化学氧化降解。     

PVA降解混合菌系生长和产酶的营养条件分析

研究碳源、氮源以及不同金属离子对PVA降解混合菌系生长和产酶的影响。结果表明,混合菌系生长过程中无机氮源优于有机氮源;补充碳源可促进混合菌系的生长,但酶活比不添加时稍有降低。金属离子对酶活影响的正交实验表明Mg2＋浓度影响最大,其次是Fe2＋和K＋浓度,Ca2＋、Mn2＋、Zn2＋和Cu2＋浓度影响较小;最佳浓度分别为Mg2＋0.05 g/L、Fe2＋0.04 g/L、K＋2 g/L和Ca2＋0.05 g/L。     

Ionic composition of submicron particles (PM1.0) during the long-lasting haze period in January 2013 in Wuhan, central China

In January 2013, a long-lasting severe haze episode occurred in Northern and Central China; at its maximum, it covered a land area of approximately 1.4 million km². In Wuhan, the largest city in Central China, this event was the most severe haze episode in the 21st century. Aerosol samples of submicron particles (PM_1.0) were collected during the long-lasting haze episode at an urban site and a suburban site in Wuhan to investigate the ion characteristics of PM_1.0 in this area. The mass concentrations of PM_1.0 and its water-soluble inorganic ions (WSIIs) were almost at the same levels at two sites, which indicates that PM_1.0 pollution occurs on a regional scale in Wuhan. WSIIs (Na⁺, NH₄⁺, K⁺, Mg²⁺, Ca²⁺, Cl^-, NO₃^- and SO₄^2-) were the dominant chemical species and constituted up to 48.4% and 47.4% of PM_1.0 at WD and TH, respectively. The concentrations of PM_1.0 and WSIIs on haze days were approximately two times higher than on normal days. The ion balance calculations indicate that the particles were more acidic on haze days than on normal days. The results of the back trajectory analysis imply that the high concentrations of PM_1.0 and its water-soluble inorganic ions may be caused by stagnant weather conditions in Wuhan.     

The impact of enhanced ammonium sulphate inputs exceeding critical load on calluna vulgaris /peat soil microcosms

Ammonium sulphate at six concentrations in simulated precipitation has been applied weekly over two years to Calluna vulgaris growing in peat soil. The nitrogen deposition treatments were chosen to embrace and exceed critical load. The growth and composition of the Calluna and the changes over time in the chemistry of the peat soil and its soil solution were monitored. In spite of significant increases in foliar nitrogen concentration in new shoots, especially in the first year, growth did not increase significantly in response to nitrogen treatment. Several factors could be contributing to the lack of significant growth response. (1) Increasing ammonium input significantly acidified the soil solution, which could adversely effect growth directly. (2) Foliar calcium concentration was reduced significantly in both years by the ammonium sulphate treatments, and more calcium was undoubtedly lost from the rooting zone at higher nitrogen inputs. (3) Foliar phosphate declined significantly between the first and second year, so lack of growth response might also reflect a phosphorus limitation. There was a distinctly visible darkening of the leaves in response to increasing ammonium applications, especially for the first year's growth, and the chlorophyll a and b concentrations in leaves from new growth at the three highest nitrogen treatments were significantly (at P <0.05) higher than those for the control. The pigment concentrations fell markedly by the end of the second season, and treatment effects were much less consistent. It is suggested that pigment analysis therefore probably has little diagnostic value for assessing damage from pollutant nitrogen effects.     

针铁矿及腐残质对水体重金属离子的吸附作用

采用针铁矿、腐殖质,针铁矿－腐殖复合微粒对重合微粒对重金属离子进行了吸附－解吸实验。结果表明它们对Cu^2 ,Zn^2 有强烈的吸附作用。针铁矿对Cu^2 和Zn^2 的吸附边界pH值分别为4．3和5．8,且吸附率可达95％以上。腐殖质对Cu^2 和Zn^2 的吸附边界pH值分别为4．1和5．6,且在pH值为8时,吸附率可达96％以上。针铁矿与腐殖形成的稳定复合微粒不仅对重金属离子具有良好的吸附作用,还具有均匀性好和沉降稳定的特点,可用于土壤修复和含重金属离子的污水的处理。     

Geochemical Characteristics of the Acid Mine Drainage in the Water System in the Vicinity of the Dogye Coal Mine in Korea

This study investigated geochemical characteristics of the acid mine drainage (AMD) discharged from the abandoned mine adits in the vicinity of the Dogye coal mine in Korea. Acid mine drainage discharged from Jeoncha pit adit of the Dogye coal mine, which is the main source of the AMD in the study area, had a pH value of 3.0 and concentrations of 2148mg SO₄ ^2– L^–1, 229mg Fe L^–1, 71mg A1 L^–1 and 11mg Mn L^–1. The reduction of some metal concentrations downstream from the discharge point could be explained on the basis of dilution and precipitation. The order of removal of metal ions downstream from the discharge point was Fe>A1, Cu>Zn, Mn. Acidity could be used as a good determining factor offering comprehensive and quantitative values for the polluting extent of acid mine drainage. The acidities existing in all acidic water samples in the Gunahan district originated primarily from mineral acidity, especially in the upper Nahan Creek from dissolved Fe and Al and in the middle and down Nahan Creek from dissolved Al. From the application of the WATEQ4F program, it was determined that predominant species of dissolved Fe in all water samples was Fe²⁺, and those of dissolved Al were AlSO₄ ⁺ and Al³⁺ except for IW2 sample which was associated with white precipitates. The species of dissolved Al in IW2 sample include also AlOH²⁺ and Al(OH)₂ ⁺. The saturation indices of goethite and haematite were positive in the water samples associated with ochrous precipitates (usually called Yellow Boy), therefore these solids might be precipitated. For the IW2 sample, the saturation indices of amorphous Al(OH)₃ and gibbsite were positive, so theoretically these solids might also be precipitated. By XRD analysis, it was found that goethite occurs in ochrous precipitates, and gibbsite in white precipitates.     

改性多壁碳纳米管对水中Cd~（2＋）的去除

为了增加多壁碳纳米管（multiwall carbon nanotubers,MWNTs）对水中Cd2＋的吸附量,使用混酸对多壁碳纳米管进行氧化处理,采用红外光谱进行结果表征,并探讨了吸附时间、pH值和MWNTs的使用量、Cd2＋的浓度及干扰离子对镉离子吸附的影响。结果表明,吸附时间为1.5 h、pH为5.3、吸附效果最佳,随MWNTs量的增加Cd2＋去除量增加,共存的阳离子会降低对Cd2＋的吸附效果,对Cd2＋的吸附符合Longmuir吸附定律。研究同时表明,pH小于2时Cd2＋能容易从碳纳米管上解吸。初步探讨了Cd2＋吸附机制。     

沈阳市PM2.5离子成分对呼吸疾病门诊数影响研究

采用时间序列的半参数广义相加模型,在控制了长期趋势、"星期几效应"和气象因素等混杂因素的基础上,分析沈阳市大气污染物及PM_2.5中水溶性离子对呼吸系统疾病门诊就诊人数的影响,并按性别和年龄分层建模.结果表明：PM_2.5及其各离子成分与呼吸系统疾病门诊人数之间存在关联,并有明显的滞后效应.受冬季供暖燃煤排放影响,PM_2.5、NO₃^-和NH₄⁺呈显著关联,在滞后累积2d后风险最大.最佳滞后时间下,PM_2.5的浓度每增加10µg/m³,对应呼吸系统疾病日门诊就诊人数增加百分比（ER）为1.31%（95% CI：1.2%~1.43%）;离子成分SO₄^2-、NO₃^-、NH₄⁺、Cl^-、K⁺、Mg²⁺、Ca²⁺和Na⁺的浓度每增加1个4分位间距（IQR）,对应的呼吸系统疾病日门诊就诊人数增加百分比（ER）分别为3.22%（95% CI：2.81%~3.62%）、4.67%（95% CI：4.13%~5.22%）、5.41%（95% CI：4.49%~6.33%）、7.38%（95% CI：3.91%~10.96%）、0.14%（95% CI：-6.34%~7.07%）、7.64%（95% CI：-11.87%~31.47%）、3.57%（95% CI：-2.83%~10.39%）和0.46%（95% CI：-16.64%~21.06%）.PM_2.5、Cl^-、Mg²⁺、Ca²⁺和Na⁺对女性呼吸疾病门诊人数的影响比对男性的影响大.PM_2.5、SO₄^2-、Cl^-、Ca²⁺和Na⁺对≥65岁的老人门诊人数的影响比对15~65岁劳动年龄人群的影响大.表明不同性别、不同年龄由于生理结构和环境因素的不同而引起的差异不同.     

共存物质对重金属絮凝齐MCC除镉性能的影响

为进一步拓展天然高分子絮凝剂壳聚糖的应用范围,以壳聚糖、L-半胱氨酸为原料,通过酰胺化反应制备一种具有重金属捕集功能的高分子重金属絮凝剂-2-氨基-3-巯基丙酰壳聚糖（MCC）,研究了水体中常见的阴阳离子、有机配位剂及浊度对MCC除镉性能的影响,探讨了絮体形貌与絮体分形维数及絮凝除镉效果间的关系。结果表明,Na＋、Cl-、N03、F-、SO4 2-的存在对MCC除Cd2＋均有促进作用,Ca2＋表现为明显的抑制作用;低浓度的EDTA对除镉有促进作用,随着EDTA浓度的增大,逐渐转为抑制作用;低浓度的腐殖酸对MCC去除Cd2＋有显著的促进作用;在一定范围内,浊度可促进MCC对Cd2＋的去除;絮体间空隙越多,絮体分形维数越小,除镉效果越好。