基于生物有效性的农田土壤磷素组分特征及其影响因素分析

适宜的磷素分级方法是研究磷素组分特征与评价其有效性的关键.以磷素的化学与生物活化特点,采用改进的生物有效性的磷素分级方法,应用其研究不同土地利用方式下旱地土与水田土中磷素组分与有效磷（Olsen-P）的关系,并分析环境因子对磷组分的影响.磷素分级方法将磷素分为4个组分：①自由扩散或根际截留的磷（CaCl₂-P）;②有机酸活化和无机弱结合磷（Citrate-P）;③系列酶矿化的有机磷（Enzyme-P）;④潜在活化的无机磷库（HCl-P）.结果表明,旱地土及水田土4种磷素组分含量均表现为：HCl-P > Citrate-P>Enzyme-P > CaCl₂-P,且旱地土各磷组分均显著高于水田土.Olsen-P与各磷素组分均呈显著正相关,表明各磷素组分对有效磷都有贡献.具体表现为：在旱地土中,Olsen-P与CaCl₂-P和Enzyme-P相关性较高（R²=0.359;R²=0.386）;在水田土中,Olsen-P与Citrate-P相关性较高（R²=0.788）,说明旱地土中有效磷主要来自土壤自由扩散的无机磷和易矿化的有机磷部分,而水田土中有效磷主要来自弱酸活化的无机磷.冗余分析结果表明,磷素组分主要受土壤pH和黏粒含量的影响,指示在农业生产活动中,可通过调节土壤pH值,提高土壤有效磷含量.     

合成洗涤剂生产废水处理技术研究

分别用混凝沉降，泡沫分离，活性炭吸附工艺进行了合成洗涤剂生产废水的处理试验。研究结果表明，混凝沉降、泡沫分离法的直链烷基苯磺酸钠去除率可以分别达到９０％、８０％以上，活性炭的ＬＡＳ吸附容量可达５９ｍｇ／ｇ以上，处理后废水的ＬＡＳ、ＣＯＤ浓度可达到国家排放标准。     

单体同位素判识地下水MTBE衰减的研究进展

有机单体同位素分析(CSIA)技术能够测定有机化合物单体中特定元素的稳定同位素比值,是一种发展中的新的技术方法。依靠CSIA提供的数据可以确定污染物MTBE来源,判识生物降解的途径,量化降解的程度。更重要的是,通过同位素动力学分馏模型的建立,CSIA技术可以作为评价和预测污染物衰减的程度和衰减时间的强有力工具。文章主要综述了应用CSIA技术解析污染物MTBE衰减过程的应用进展。     

镉同位素及其环境示踪

随着多道接收电感耦合等离子体质谱仪(MC-ICPMS)的发展和广泛应用,镉(Cd)稳定同位素已成为当前非传统同位素地球化学的研究热点之一。本文对Cd同位素的分析方法、组成特征、变化规律、分馏机制及环境应用等问题进行了系统评述。总体来说,地球样品的Cd同位素组成(δ114/110 Cd)分馏较小(-2.47‰~+3.17‰),陨石等地外物质同位素分馏较大(-9.07‰~+16.13‰),已发现的分馏过程包括蒸发/冷凝过程、吸附沉淀/溶解过程、生物吸收过程。同时,Cd同位素作为一种全新的地球化学指标,可指示物源、天体演化、海洋初级生产力及营养物质循环、全球碳循环等过程;有效示踪环境介质与生物体中Cd的污染来源,为环境科学的研究提供新的视角和信息。     

Effects of pre-ozonation on organic matter removal by coagulation with IPF-PACl

Introduction Ozonation as one of pre-oxidation techniques has complicated influences on coagulation in terms of turbidity and organic matter removals (Edwards and Benjamin, 1992a, b). Many studies have been carried out on the effects of ozone on coagulation, however there still exists some discrepancies among different researches. The mechanisms involved in the interac- tions between pre-ozonation and coagulation remain unclear. Reckhow and Singer (1984) reported that UV254, TOC, and TOX …     

Removal of humic acid using TiO2 photocatalytic process--fractionation and molecular weight characterisation studies

The photocatalytic removal of humic acid (HA) using TiO₂ under UVA irradiation was examined by monitoring changes in the UV₂₅₄ absorbance, dissolved organic carbon (DOC) concentration, apparent molecular weight distribution, and trihalomethane formation potentials (THMFPs) over treatment time. A resin fractionation technique in which the samples were fractionated into four components: very hydrophobic acids (VHA), slightly hydrophobic acids, hydrophilic charged (CHA) and hydrophilic neutral (NEU) was also employed to elucidate the changes in the chemical nature of the HA components during treatment. The UVA/TiO₂ process was found to be effective in removing more than 80% DOC and 90% UV₂₅₄ absorbance. The THMFPs of samples were decreased to below 20 μg l⁻¹ after treatments, which demonstrate the potential to meet increasingly stringent regulatory level of trihalomethanes in water. Resin fractionation analysis showed that the VHA fraction was decreased considerably as a result of photocatalytic treatments, forming CHA intermediates which were further degraded with increased irradiation time. The NEU fraction, which comprised of non-UV-absorbing low molecular weight compounds, was found to be the most persistent component.     

Assessment of pesticide availability in soil fractions after the incorporation of winery-distillery vermicomposts

The influence of two vermicomposts from winery and distillery wastes on the distribution of diuron in agricultural soil was studied. Physical soil fractionations at 0, 9, 27, 49 and 77 days, allowed the quantification of pesticide residues in different particle-size fractions, coarse waste (WF), sand-sized (SF), silt-sized (SiF), clay-sized (CF) and dissolved organic matter-sized fraction (DOM). The SiF made a greater contribution to the formation of non-extractable residues in unamended soil, but when vermicomposts were added, new sorption sites in WF appeared, being higher for the more humified vermicompost V2. The dissolved organic carbon (DOC) increased with the addition of vermicompost, but the concentration of the desorbed 14C-radiochemical did not increase. Non-significant increment was observed with time for the non-extractable fraction with amendments. Diuron was transformed in all samples, although less than 0.5% was mineralized. The main effect caused by vermicomposts was a reduction in the availability of diuron in soil.     

水镁石-水体系氢同位素分馏系数的低温实验研究

分别以氯化镁和氮化镁作为起始物料，在低温（25～90℃）溶液中采用化学方法合成水镁石．然后分别测定水镁石和水的氢同位素组成，得到水镁石-水体系的氢同位素分馏方程为：103lna=－4．88×106／T2－22．54。由于矿物-水体系氢同位素分馏的压力效应，本研究通过大气压力下的实验得到的分馏系数值，系统地低于根据高温（510～100℃）高压（100～103MPa）热液交换实验结果向低温方向外推获得的分馏系数值。与已知的其它含羟基矿物-水体系低温氢同位素分馏曲线比较的结果表明，在热力学平衡条件下，水镁石相对于高岭石和伊利石／蒙脱石亏损D，但相对于外铁矿富集D。因此，合羟基矿物存在如下D富集顺序：Al－OH＞Mg－OH＞Fe－OH。     

冰封期前后河流底泥中溶解性有机物组分的荧光特性的变化

以沈阳市新开河为研究对象,考察了冰封期前、后河流底泥中溶解性有机物(DOM)组分荧光特性的变化.按照DOM在XAD树脂上的吸附特性将其分为5个部分:疏水性有机酸(HPO-A)、疏水性中性有机物(HPO-N)、过渡亲水性有机酸(TPI-A)、过渡亲水性中性有机物(TPI-N)和亲水性有机物(HPI).结果表明:HPO-A是河流底泥中的主要DOM组分,在冰封期前、后分别占溶解性有机碳(DOC)的41.2%~69.5%和38.9%~63.9%.冰封期前河流底泥中的DOM及HPO-A、HPI的DOC值均高于冰封期后.三维荧光光谱结果显示,冰封期前、后河流底泥DOM组分中含有类腐殖酸荧光物质,类富里酸荧光物质,类芳香族蛋白质荧光物质和类溶解性微生物代谢产物荧光物质,并且类芳香族蛋白质荧光物质在各DOM组分中的含量最高.冰封期后HPO-A、HPI中荧光物质的含量低于冰封期前.同步荧光光谱结果显示,在冰封期河流底泥DOM组分中激发波长分别为285~295 nm和330~350 nm的荧光物质向水体释放,导致其在底泥DOM组分中相对含量的显著降低.     

Cu在黑土中形态特性分析及施用有机肥的影响

通过小麦盆栽试验研究了黑土中Cu的分布特征、动态变化及有机肥施用的影响.结果表明,无论外源Cu添加量高或低,土壤中Cu的形态均主要以可氧化态为主,所占比例为40.4%～65.0%.随着外源Cu添加量的增加,弱酸溶解态Cu所占比例稍有增加,可还原态Cu含量及其所占比例均显著增加,残渣态Cu所占比例显著降低,可见外源Cu添加量的增加能提高土壤中Cu的生物有效性.与2009年相比,黑土中弱酸溶解态Cu的分配比例在2010年迅速下降,而残渣态Cu的比例显著上升,表明随着时间的变化Cu的稳定化作用不断加强,生物有效性降低.1%有机肥施用明显降低了Cu的移动性,弱酸溶解态Cu的下降幅度和残渣态Cu的上升幅度都明显增大.低剂量Cu(<200mg·kg-1)可促进小麦的生长,使其生物量增加,但高剂量Cu(高于600mg·kg-1)对小麦有显著的毒害作用.且当Cu添加量很高时,小麦对Cu的吸收量在2010年高于2009年,表明Cu在黑土中的短期稳定作用对Cu的生物有效性和作物吸收并未产生显著影响.