Mobility of heavy metals as related to soil chemical and mineralogical characteristics of Brazilian soils

In order to better understand the relationship between soil characteristics and mobility of some heavy metals, correlation studies were conducted in samples of unlimed and limed A, B and C horizons of three Brazilian soils, representative of the majority of the tropical soils. A number of chemical and mineralogical characteristics of one Oxisol and two Ultisols were related to the retardation factors (Rf) for zinc (Zn), cadmium (Cd), copper (Cu) and lead (Pb). The retardation factors, obtained in leaching column experiments, were used as an estimate of solute movement in the profile. Soil types and soil horizons were found to influence metal retardation factors which, in turn, correlated better with the chemical than the mineralogical soil characteristics. For the unlimed soil samples, the soil characteristics that significantly correlated with Zn-Rf and Cd-Rf were the sum of exchangeable bases (SB), and soil exchangeable (Ca-KCl) and non-exchangeable (Ca-HCl) calcium contents. These results showed the strong influence of the cation exchange phenomenon on the retention and mobility of these two metals. For Cu and Pb, not only SB, cation exchange capacity (CEC) and Ca-KCl and Ca-HCl but also the organic matter correlated well with the Rf, showing that complex or chelate formation may play an important role in the movement of these elements. The important soil chemical characteristics related to the retardation factors in the limed soil samples were SB for Cd, and Ca-HCl for Cu and Pb, suggesting that precipitation may also influence the mobility and retention of the latter two heavy metals in these soil samples. Soil pH influenced the heavy metals adsorption and movement as shown by the significant correlation with the retardation factors when the combined data for the unlimed and limed soil samples was considered.     

盐度胁迫对云纹石斑鱼鳃离子调节酶及渗透压的影响

为探讨云纹石斑鱼鳃离子调节酶活力及血清渗透压对盐度骤降的响应,设置4个盐度梯度(27、21、15和9)对云纹石斑鱼进行盐度骤降胁迫试验,在0、1 d、2 d、3 d和7 d时取样,测定其鳃中Na+/K+-ATP(NKA)酶、Ca~(2+)-ATP酶(Ca~(2+)-ATPase)、琥珀酸脱氢酶(SDH)、乳酸脱氢酶(LDH)活力及血清渗透压。结果表明,盐度21组与15组NKA及Ca~(2+)-ATPase活力在第1 d大幅上升,显著高于对照组(p0.05),随后下降趋于稳定,而盐度9组NKA及Ga2+-ATPase活力一直呈下降趋势;血清渗透压呈先下降后上升的变化趋势(p0.05);SDH活力变化与离子酶一致(p0.05);LDH活力变化与离子酶相反(p0.05)。研究表明,在盐度骤降的情况下,云纹石斑鱼鳃进行渗透压调节分为两个阶段,一是应激反应阶段,此时NKA及Ca~(2+)-ATPase迅速升高,血清渗透压降低;二是适应阶段,离子酶活力下降趋于稳定,血清渗透压升高恢复至正常水平,而且SDH与LDH酶活力也相应变化,为渗透压调节提供能量。     

闽三角地区碳排放时空差异及影响因素研究

以闽三角地区为研究对象,以2005~2017年为研究期,构建城市尺度的碳排放清单,应用对数平均迪氏指数分解方法从时间维度的纵向比较和典型年份城市横向比较两个维度开展了驱动因素的分解分析及评价,探讨了闽三角碳排放变化影响因素的时空差异.结果显示：研究期内闽三角CO₂排放增长较快,从2005年的74.08Mt增加到2017年169.48Mt,增幅为128.75%.其中,泉州贡献最大,占比为67.93%.碳排放变化趋势分析来看,产业结构和经济增长为导致闽三角地区碳排放量增长的主要因素,累计贡献度分别为30.38%和12.21%,能源结构为抑制碳排放的重要影响因素,累计贡献度为-45.76%.时空差异上看,能源结构效应在研究期内均表现为抑制效应,最大贡献率为52.95%;而产业结构效应均表现为促进效应,最大贡献率为33.85%.在研究期内,漳州市碳减排力度最大,最大净减排148.27Mt.而泉州市经济增长和产业结构效应贡献率较大,未来仍具有较大的减排空间.厦门市经济增长和产业结构效应贡献率均低于参考值,且在研究期内变动幅度较小,碳减排压力较低.研究结果深化了闽三角地区碳排放的时空格局及影响因素的科学认识,为闽三角地区及相似城市群的减排治理提供了有益借鉴.     

一次冷锋过程中我国区域空气污染边界层特征

利用常规地面气象和探空资料、ERA-interim再分析资料、以及全国PM_2.5浓度数据,针对2015年3月7~11日一次冷空气南下的锋面天气过程中,我国华北、华东地区出现的大范围空气污染,开展了高空各层天气形势分析,以及本次过程中污染区域由北至南6个城市（北京、章丘、郑州、南阳、武汉、长沙）边界层气象要素的垂直结构及其时空演变特征的研究.结果表明：在污染前期（3月7~8日）中高纬度500hPa平直的纬向环流和地面均压场,为污染天气的发生和维持以及空气污染物的集聚提供了有利的环流场.污染中期（3月8~10日）冷空气南下,地面冷高压向华东地区移动,重污染区域随冷高压前部的弱低压场或均压场由北向南移动.伴随着天气系统移动,六个地面观测站的边界层特征在时空上表现出相似性,由北向南各站在污染期间先后出现多层逆温,风速较小,逆温层下相对湿度较大.此次多层逆温的形成是由于夜间近地面辐射冷却、冷锋移动过程中产生的锋面逆温以及边界层以上的下沉运动造成的.本研究揭示了在天气系统移动中,位于天气系统相同部位站点的边界层结构具有共同的特征,及其与空气污染的关系.     

Reduced adsorption of ametryn in clay, humic acid, and soil by interaction with ferric ion under Fenton treatment conditions

Previous work in our laboratory indicated a weak interaction between ferric ion and several triazine/triazinone herbicides during a Fenton treatment process, and the intensity of the interaction was calculated. To further support the existence of this weak interaction, the adsorption of ametryn, a triazine herbicide, was investigated in kaolinite clay, humic acid, and soil under pseudo-Fenton conditions. At a low addition rate of ferric ion, the adsorption of ametryn in clay, humic acid, and soil was enhanced due to the decreased pH resulting from the hydrolysis of ferric ion. But the pH effect was totally neutralized and the adsorption of ametryn was significantly reduced by further addition of ferric ion, demonstrating the existence of the weak interaction between ametryn and ferric acid. Further study showed that the adsorption-reduction effect of ferric ion existed not only with ametryn but also with several other triazine/triazinone herbicides. This weak interaction may accelerate the desorption process during the remediation of triazine/triazinone herbicide-contaminated soil using a Fenton/Fenton-like treatment, but it may also impede the degradation of these herbicides.     

Methods development and use of macroinvertebrates as indicators of ecological conditions for streams in the Mid-Atlantic Highlands Region

The Mid-Atlantic Highlands Assessment (MAHA) included the sampling of macroinvertebrates from 424 wadeable stream sites to determine status and trends, biological conditions, and water quality in first through third order streams in the Mid-Atlantic Highlands Region (MAHR) of the United States in 1993–1995. We identified reference and impaired sites using water chemistry and habitat criteria and evaluated a set of candidate macroinvertebrate metrics using a stepwise process. This process examined several metric characteristics, including ability of metrics to discriminate reference and impaired sites, relative scope of impairment, correlations with chemical and habitat indicators of stream disturbance, redundancy with other metrics, and within-year variability. Metrics that performed well were compared with metrics currently being used by three states in the region: Pennsylvania, Virginia, and West Virginia. Some of the metrics used by these states did not perform well when evaluated using regional data, while other metrics used by all three states in some form, specifically number of taxa, number of EPT taxa, and Hilsenhoff Biotic Index, performed well overall. Reasons for discrepancies between state and regional evaluations of metrics are explored. We also provide a set of metrics that, when used in combination, may provide a useful assessment of stream conditions in the MAHR.     

Trihalomethane formation potential of filter isolates of electrolyte-extractable soil organic carbon

Certain organic C moieties of soil origin in drinking source waters of Sacramento-San Joaquin Delta (Delta) can react with chlorine to form trihalomethanes (THMs) during the disinfection process. Isolation and characterization of them and quantitation of their THM formation potential (THMFP) is necessary for developing effective strategies to reduce their influxes in Delta waters and for removing them during drinking water treatment. In this study, organic C from two Delta soils was extracted using deionized H(2)O and four Na- or Ca-based electrolytes of varying electrical conductivity values. Extracts were filtered into particulate, colloidal, fine colloidal, and soluble organic C for quantitation and THMFP determination. Results suggested that <1.5% of soil organic C was electrolyte-extractable. The soluble organic C fraction from both soils dominated in quantity and THMFP. Electrolyte effects were cation dependent. Sodium-based electrolytes at either conductivity level did not significantly decrease extractable organic C (EOC) or THMFP compared with deionized H(2)O. In contrast, Ca-based electrolytes reduced EOC and THMFP by >50% even at 1 dS m(-1). Further increase in Ca concentration did not significantly decrease EOC or THMFP. Most reduction in EOC and THMFP by Ca-based electrolytes occurred with the fractions other than the soluble organic C. Results suggested that under natural soil leaching and runoff conditions, the majority of THMFP is associated with organic C of <0.025 mum in diameter. Further molecular characterization of the fractions with high THMFP may help understand the nature of chlorine-reactive organic C from Delta soils.     

Trihalomethane reactivity of water- and sodium hydroxide-extractable organic carbon fractions from peat soils

Certain organic carbon moieties in drinking source waters of the Sacramento-San Joaquin Delta can react with chlorine during disinfection to form potentially carcinogenic and mutagenic trihalomethanes. The properties of reactive organic carbon in Delta waters, particularly those of soil origin, have been poorly understood. This study attempts to characterize trihalomethane reactivity of soil organic carbon from three representative Delta peat soils. Soil organic carbon was extracted from all three soils with either deionized H2O or 0.1 M NaOH and sequentially separated into humic acids, fulvic acids, and nonhumic substances for quantitation of trihalomethane formation potential. Water-extractable organic carbon represented only 0.4 to 0.7% of total soil organic carbon, whereas NaOH extracted 38 to 51% of total soil organic carbon. The sizes and specific trihalomethane formation potential (STHMFP) of individual organic carbon fractions differed with extractants. Fulvic acids were the largest fraction in H2O-extractable organic carbon, whereas humic acids were the largest fraction in NaOH-extractable organic carbon. Among the fractions derived from H2O-extractable carbon, fulvic acids had the greatest specific ultraviolet absorbance and STHMFP and had the majority of reactive organic carbon. Among the fractions from NaOH-extractable organic carbon, humic acids and fulvic acids had similar STHMFP and, thus, were equally reactive. Humic acids were associated with the majority of trihalomethane reactivity of NaOH-extractable organic carbon. The nonhumic substances were less reactive than either humic acids or fulvic acids regardless of extractants. Specific ultraviolet absorbance was not a good predictor of trihalomethane reactivity of organic carbon fractions separated from the soils.     

阿勒泰森林消防：扎实推进自我教育活动

<正>为解决新体制下队伍思想政治教育存在的突出问题,自2020年以来,新疆森林消防总队针对眼下消防救援人员文化程度高、自我意识强等特点,创新开展“人人上讲台”群众性自我教育活动,充分发挥思想政治教育的政治引领功能,积极创新教育理念、内容和方法,激发消防救援人员主观能动性,让他们从幕后走向台前,在研究教育好别人的同时提升自我认知水平和全面素养,推动实现教育落实和教育成效的双向提高。     

Compliance with Wetland Mitigation Standards in the Upper Peninsula of Michigan, USA

The United States has lost about half its wetland acreage since European settlement, and the effectiveness of current wetland mitigation policies is often questioned. In most states, federal wetland laws are overseen by the U.S. Army Corps of Engineers, but Michigan administers these laws through the state's Department of Environmental Quality (MDEQ). Our research provides insight into the effectiveness of the state's implementation of these laws. We examined wetland mitigation permit files issued in Michigan's Upper Peninsula between 2003 and 2006 to assess compliance with key MDEQ policies. Forty-six percent of files were out of compliance with monitoring report requirements, and forty-nine percent lacked required conservation easement documents. We also conducted site assessments of select compensatory wetland projects to determine compliance with MDEQ invasive plant species performance standards. Fifty-five percent were out of compliance. We found no relationship between invasive species noncompliance and past site monitoring, age of mitigation site, or proximity to roads. However, we found wetland restoration projects far more likely to be compliant with performance standards than wetland creation projects. We suggest policy changes and agency actions that could increase compliance with wetland restoration and mitigation goals.