不同钝化剂和培养时间对Cd污染土壤中可交换态Cd的影响

原位化学钝化技术是修复重金属污染土壤的重要途径之一,通过施入一些钝化剂以降低土壤中重金属有效态含量,从而减少其迁移及对植物的毒害。选取羟基磷灰石（HA）、磷矿粉（PRX和PRH）、沸石、赤泥、新鲜植物残体、玉米秸秆粉末以及相应的处理共21种钝化剂,在同一培养条件和添加浓度下,比较其对人工Cd污染土壤中可交换态Cd含量的影响,并分析了其在不同培养时间对钝化效果的时间效应,试验的结果对于筛选Cd污染土壤钝化剂有着重要的意义。结果表明,纳米化赤泥、羟基磷灰石和纳米化酸洗赤泥可显著降低土壤中可交换态Cd含量,钝化比例高达35%-55%;赤泥、酸洗赤泥、沸石达15%-25%;富含巯基植物蒜苗、油菜、大葱植物残体也可达20%-25%。磷矿粉、大葱粉末、玉米秸秆和巯基化玉米秸秆的钝化效果相对较差;HA、铵型沸石、纳米赤泥、酸洗纳米赤泥、干油菜粉末、酸洗赤泥对可交换态Cd的钝化效果的时间效应不明显;赤泥、大葱残体、特别是玉米秸秆和巯基玉米秸秆随时间增长钝化效果增加显著,在8周和16周时段钝化效果较好。     

羊栖菜粉对水溶液中Cu2+的吸附效果

以羊栖菜粉为吸附剂,研究羊栖菜粉对水溶液中Cu²⁺的吸附特性及吸附机理,考察羊栖菜对重金属铜的吸附能力,以扩展羊栖菜的综合利用范围。采用控制变量法考察pH值、吸附剂浓度、金属离子初始浓度和离子强度等环境因素对水溶液中Cu²⁺去除效果的影响,通过模拟吸附动力学和热力学试验考察羊栖菜粉对Cu²⁺的吸附特性,并采用SEM、FTIR等方法初步分析了羊栖菜粉对Cu²⁺的吸附机理。结果表明,在吸附温度35℃、初始浓度50 mg·L^-1、吸附剂浓度1 g·L^-1条件下,羊栖菜粉对Cu²⁺的去除率可达89.27%。当吸附时间为10 min时,Cu²⁺去除率达总去除率的90%以上;当吸附时间为60 min时,基本达到吸附平衡。羊栖菜粉吸附Cu²⁺的动力学数据符合准二级动力学模型,相关系数均在0.999 0以上。Langmuir可以很好地拟合热力学试验得到的平衡数据,理论最大吸附容量为71.17 mg·g^-1。羊栖菜粉对Cu²⁺的吸附有多种反应参与,参与络合反应的官能团主要有-OH、-NH、-COO^-。羊栖菜粉对Cu²⁺的去除率较高,吸附性能良好,可通过解吸实现吸附剂的再生。     

测定土壤硝态氮的紫外分光光度法和镉柱还原法比较

使用改进的紫外分光光度法(校正因素法)和基于镉柱还原的流动注射分析法(镉柱还原法)测定了中国10种不同类型土壤的NO3–-N含量,分析了两种方法的差异性及其适用性。统计分析表明,改进紫外分光光度法与镉柱还原法测定的结果具有极显著的相关性,测定样品的准确度介于89%~104%,具有可比性。在浓度适用上略有差异,对NO3–-N含量极低的土壤样品,采用镉柱还原法可提高精确度;对于NO3–-N含量高的土样选用紫外法可提高测定精确度,测定结果变异性低于镉柱还原法,且紫外法测定值都要高于镉柱还原法。从仪器操作及校准角度来看,紫外法测定操作过程简便,影响因子较少,对NO3–-N批量快速测定更为适用。     

用于表征三七种植区土壤中可利用态砷的化学提取剂的筛选

为正确表征云南文山三七种植区土壤中植物可利用态砷,选取NaH2PO4（0.5mol·L-1）、H2O、H3PO4（0.2mol·L-1）、EDTA（0.0625mol·L-1,pH=7）、NH4C（l1.0mol·L-1）和（NH4）2SO（40.05mol·L-1）6种提取剂,比较了它们对土壤中砷的提取效果,及其所提取的砷与三七植株各部位砷含量之间的相关关系。结果表明,NaH2PO4、H3PO4和（NH4）2SO4这3种提取态砷与土壤总砷呈极显著正相关,相关系数分别为0.8359、0.8177和0.8810。NaH2PO4和H3PO4的提取效率较高,平均提取效率分别为6%和11%;而（NH4）2SO4提取效率较低,平均仅为0.084%。NaH2PO4和（NH4）2SO4提取态砷与三七主根、须根和茎部砷含量呈显著正相关,H3PO4提取态砷与三七主根和须根砷含量呈显著正相关。综合考虑认为NaH2PO（40.5mol·L-1）是最佳提取剂,H3PO（40.2mol·L-1）提取剂次之,这两种提取剂均可较好地表征土壤中砷的三七可利用性。     

柠檬酸对蒙山茶园土壤微团聚体吸附-解吸Cu2+的影响

以蒙山茶园土为对象,运用平衡液吸附法以及NaNO3溶液解吸法探讨了柠檬酸对原土及各粒径土壤微团聚体吸附-解吸Cu2+的特性,以期明确柠檬酸对土壤吸附解吸铜的过程中产生的影响。结果表明,加入柠檬酸后,随着Cu2+浓度的增加,原土和各粒径土壤微团聚体对Cu2+的吸附有所增加,吸附量大小顺序为:(0.002mm)(0.053~0.002)mm原土(2~0.25)mm(0.25~0.053)mm,与土壤微团聚体中游离氧化铁、阳离子交换量以及有机质含量大小顺序一致;柠檬酸对Cu2+的吸附既有促进作用又有抑制作用,低浓度(0~1mmol/L)的柠檬酸促进土壤微团聚体对Cu2+的吸附,而高浓度(1mmol/L)的柠檬酸则降低其吸附,吸附量在柠檬酸浓度为0.5mmol/L时达到最大;Langmuir、Freundlich、Temkin 3种方程对其等温吸附过程的拟合均达到了极显著水平(p0.01),其中以Langmuir方程的拟合效果最佳,说明加入柠檬酸后的原土及各粒径土壤微团聚体对Cu2+的吸附以单层吸附为主;随着铜浓度的上升,土壤微团聚体对Cu2+的易解吸率不断增加,柠檬酸的进一步加入使得土壤微团聚体对Cu2+的解吸率上升,而解吸大小顺序与吸附顺序相反。     

测定土壤硝态氮的紫外分光光度法与其他方法的比较

使用酚二磺酸法、还原蒸馏法、镀铜镉还原．重氮化偶合比色法和改进紫外分光光度法（校正因数法）测定了中国9种不同类型土壤的硝态氮含量，分析了改进紫外分光光度法与其余三种测定方法的差异及其适用性。统计分析表明对于有机质含量低于50g kg^-1的矿质土壤，可以使用2．2作为校正因数，四种分析方法的测定值具有极显著的相关性，尤其是紫外分光光度法与酚二磺酸法的测定结果最为接近，没有极显著差异；对于有机质含量接近和高于50g kg^-1的土壤，校正因数还需要修改。紫外分光光度法具有操作简单、测定速度快等优点，适用于批量快速测定。     

恒电荷土壤及可变电荷土壤与离子间相互作用的研究Ⅲ Cu2+和Zn2+的吸附特征

研究了3种典型可变电荷土壤和4种典型恒电荷土壤在不同pH和不同浓度下单纯及共存体系中Cu2 和Zn2 的吸附及其影响因素。结果表明,两类土壤对Cu2 或Zn2 的吸附量均随平衡浓度增加而增大,符合Langmuir吸附等温式;当Cu2 、Zn2 浓度一定时,pH升高使Cu2 、Zn2 吸附量增大,但当pH >5时,Cu2 、Zn2 吸附量随pH变化甚微,出现一个接近最大吸附量的“平台”。当添加Cu2 、Zn2 浓度相同,但二种离子的总浓度不同时,平衡液的Cu2 /Zn2 浓度比均小于1,说明两类土壤对Cu2 的吸附选择性大于Zn2 ,且这种趋势不因pH和离子浓度而改变。当Cu2 、Zn2 共存时,使可变电荷土壤的Zn2 吸附量减小约70 % ,是恒电荷土壤降低量的约1.5倍;可变电荷土壤吸附一个Cu2 或Zn2 时所释放H 的平均数,明显大于恒电荷土壤者,说明可变电荷土壤对Cu2 及Zn2 的吸附中专性吸附的比例较恒电荷土壤大     

基于Tessier法的土壤中不同形态镉的转化及其影响因素研究进展

土壤重金属形态分析对土壤污染修复具有重要意义。综述了几种常见的重金属形态分析方法并基于Tessier五步连续浸提法分析土壤中Cd形态转化规律,进一步总结了土壤的理化性质对Cd形态的影响。不同类型土壤中Cd形态的含量分配比不同,土壤中的可交换态Cd含量较高,迁移性较强,对生物危害较大,因此可通过改变土壤pH值、土壤有机质和土壤氧化还原条件等土壤理化性质使可交换态Cd向残渣态Cd转化,进而降低土壤中Cd对生物的毒性作用。旨在深化读者对土壤Cd污染的认识,并为土壤Cd污染治理与修复提供参考。     

小麦-玉米轮作土壤中磷肥化学行为及积累态磷生物有效性的研究

本文用改进的石灰性土壤无机磷分级方法系统地研究了河北省主要类型土壤的磷素形态,小麦 玉米轮作中水溶性磷肥施入土壤后的动态转化。研究结果表明,潮褐土、褐土、潮土的磷素形态为:无机磷占土壤全磷的73.2%～96.4%,Ca-P占无机磷的79.1%～90.8%,Ca10－P占Ca-P的51.7%～97.4%。小麦 玉米轮作中水溶性磷肥施入土壤后的化学行为:第一年,小麦和玉米共吸收利用了施入磷的２４.６％～２７.４％,作物主要消耗了土壤积累态Ca2－P,其次为Ca8－P;第二、三年,作物分别吸收利用了施入磷的１９.０％～２０.４％、１２.４％～１７.３％,主要消耗了土壤积累态Ca8－P,其次为Ca2－P、Ａｌ-Ｐ,再次为Ｆｅ-Ｐ。土壤积累磷以Ca8－P为主,其次为Ca2－P,再次为Ａｌ-Ｐ、Ｆｅ-Ｐ。土壤各形态无机磷的转化主要发生在Ca2－P与Ca8－P之间。化学磷肥与有机肥配施提高了土壤积累态磷的有效性。施用磷肥的效应在连续３年小麦-玉米轮作中均表现明显的增产效应。     

土壤中微量钒的分光光度测定方法研究 ——1 （2 吡啶偶氮） 2 萘酚-过氧化氢-十二烷基苯磺酸钠法

对钒(V)和1-(2-吡啶偶氮)-2-萘酚(PAN)-过氧化氢-十二烷基苯磺酸钠(SDBS)显色反应进行了试验,结果表明:在1 mol.L-1盐酸介质中,在SDBS存在下,钒与1-(2-吡啶偶氮)-萘酚和过氧化氢生成红色的多元络合物,络合物最大吸收波长为575 nm,表观摩尔吸收率为3.64×104L.mol-1.cm-1,钒的浓度在0.2～1.2μg.mL-1内符合比耳定律。络合物的组成比为n钒∶nPAN∶n过氧化氢=1∶1∶1。该方法用于土壤中钒的测定,测定值的相对偏差(n=20)均小于6%,回收率为100.4%～105.6%。     

Adsorption of Cu2+ on Amine-Functionalized Mesoporous Silica Brackets

A directly amine-functionalized mesoporous silica (AMS) was prepared via an anionic surfactant-mediated synthesis method and used as adsorbents for deep removal of Cu²⁺ ions from aqueous solution at room temperature. The synthesized AMS had been characterized by X-ray diffraction, nitrogen physisorption measurement, and thermogravimetric analysis. The amine groups prefer to position to the surface of AMS material due to the S^?N⁺????I^? mechanism. Copper adsorption process had been studied from both kinetic and equilibrium points of view for AMS material. Experiments proved that the aqueous Cu²⁺ adsorption rates were fast and adsorption capacity was about 53.3?mg/g.     

基于Gouy-Chapman理论估算碱金属离子在Cu2+-蒙脱石表面Hofmeister能

Hofmeister效应在离子交换吸附过程中具有重要的科学意义。本研究基于Gouy-Chapman理论研究三种碱金属阳离子（Na+、K+、Cs+）在Cu2+-蒙脱石饱和样表面吸附过程的Hofmeister效应,进一步计算了离子-表面Hofmeister能以及表观电荷系数。研究发现：（1）Na+ 、K+ 、Cs+在Cu2+-蒙脱石表面的吸附均表现为弱静电力作用下的一级动力学过程, 平均吸附速率以及平衡吸附量均表现出明显的Hofmeister效应,呈现出Na+ < K+ < Cs+的趋势;（2）Hofmeister能随着电解质浓度的降低而增加,在Cs+-粘土矿物相互作用中,Hofmeister能为主要贡献者,在K+/Na+-粘土矿物相互作用,经典库伦能中为主要贡献者;（3）非经典极化作用显著增大了离子的表观电荷系数,Na+、K+、Cs+的表观电荷系数分别从标准的+1值增加为+1.14、+1.76和+2.78。本研究明确了Hofmeister效应主要来源于离子的非经典极化作用引起的离子与表面相互作用能的差异,为阐明土壤这一特殊体系的界面反应机制提供了新的思路。     

基于VNIR和机器学习算法的原状土剖面Cu含量预测

快速测量土壤剖面重金属含量是评估土壤重金属污染状况并选择相应修复技术的关键。为了探讨可见光-近红外光谱法（Visible and Near-Infrared Reflectance Spectroscopy,VNIR）预测原状土壤剖面重金属含量的潜力,以江西省两个典型工矿厂周边农田土壤为研究对象,共采集了19个深度约100 cm的完整土壤剖面样品,分别测定土壤剖面样品的VNIR数据及其Cu含量。采用偏最小二乘回归法（Partial Least Squares Regression,PLSR）、Cubist混合线性回归决策树（Cubist Regression Tree,Cubist）、高斯过程回归（Gaussian Process Regression,GPR）和支持向量机（Support Vector Machine Regression,SVM）方法研究不同光谱预处理方法对土壤Cu含量预测精度的影响。结果显示,Cubist、GPR和SVM这三种机器学习算法的预测精度普遍高于PLSR,其中一阶导数（First-Order Derivative,FD）预处理的SVM模型预测精度最高（R2=0.95,均方根误差为7.94 mg/kg,相对分析误差为4.34）。这表明利用VNIR和机器学习可以对原状土壤剖面Cu含量进行有效预测,为快速监测Cu及其他重金属含量的相关研究提供参考。     

Observations on the bismuth sulfide colorimetric procedure for sulfate analysis in soil

Abstract

The bismuth sulfide and methylene blue colorimetric finishes for soil sulfate determination by the Johnson‐Nishita distillation method were examined and compared. Both procedures gave comparable results when applied to soils and soil extracts, but the bismuth method was more rapid and more reliable. Nitrogen flow rate over the range 100–500 ml/min was not critical for the bismuth method, provided appropriate distillation times were employed. However, the release and transfer of hydrogen sulfide in the bismuth method was effected in one‐third of the time required for the méthylène blue finish, largely due to the elimination of a gas‐washing step. Predrying of soil extract samples increased recovery of hydrogen sulfide with the bismuth procedure arid could be used to increase sensitivity. Nitrate interference was observed with the bismuth procedure but attributed to interference during the reduction step. The bismuth procedure can readily be adapted for microdetermination in the 0–40 ppm sulfate‐S range.     

基于GIS的安塞县土壤水分制图及其数量分析

 以空间图形和数据库为基础,利用GIS安塞县的土壤水分样点数据与地理数据结合起来,建立不同利用类型土地类型坡度分级的浮点型土壤含水率字段,对安塞县域尺度土壤水分制图及其定量化方法进行研究和探讨,对安塞县不同土层土壤水分状态和分布进行定量分析。结果表明:从土壤水分结构看,安塞县土壤水分总体上处于较低水平,0～500 cm土层平均土壤含水量在含水量为8.6%～10.8%的分布面积占到总土地面积的75.34%,在含水量<6.4%和6.4%～8.6%的分布面积占到总土地面积的19.36%,其中含水率<6.4%的土壤干层面积占到总土地面积的9.23%,其在上层分布面积大于下层,分布在一般（≥10.8%）以上水平的面积仅占总土地面积的5.31%。安塞县每2的土壤水库蓄水量在0～120cm土层仅有0.060.07 m3,而其他土层都在0.15m3以下。说明安塞县土壤水分环境极差,土壤水库的调节作用对于林木生长极其有限,大面积植树造林超越了安塞县土壤水库的供水和调水能力,是不适宜的;因此,在以适地适树原则适应土壤水分环境的同时,应加强土壤水分环境的改善。     

Study on soil cracks in pneumatic subsoiling based on LSTM

This paper reports research based on pneumatic subsoiling and the design of a pneumatic subsoiling mechanism to overcome the problems of high resistance and high energy consumption of subsoiling. By analysing soil-specific resistance, soil disturbance rate and soil bulkiness under different air pressure conditions, it is concluded that pneumatic subsoiling can effectively break the soil plough pan and reduce resistance to subsoiling. In order to analyse the impact of air pressure on subsoiling, in this study, principal component analysis was used to analyse the pneumatic subsoiling disturbance parameters (working air pressure, working depth and working speed), and the test results show that the contribution of air pressure to subsoiling resistance and subsoiling disturbance surface reached 24% and 25%, respectively. An orthogonal test was used to analyse the specific resistance of subsoiling, and its significance coefficient is 0.95. Long short-term memory neural networks (LSTM) and bidirectional long short-term memory neural networks Bi-LSTM. are used to predict the cracks on the disturbed surface of subsoiling. LSTM is a method to predict future occurrence using time series data, which can be used to predict the cracks on the disturbed surface of soil, while Bi-LSTM network is an innovative computing paradigm, which learns bidirectional long-term correlation between time step and sequence data, to predict the trend of fissures on the disturbed soil surface. The RSME of LSTM and Bi-LSTM are 4.80 and 6.55, and their determinative factor R² is 0.95 and 0.94 respectively, which indicates that LSTM and Bi-LSTM can effectively predict the cracks of pneumatic subsoiling. By analysing the specific resistance of pneumatic subsoiling, it can be shown that pneumatic subsoiling can reduce subsoiling resistance and expand the disturbance surface of subsoiling so as to achieve the effects of subsoiling, drag reduction and reduction of fuel consumption.     

A simple procedure for colorimetric determination of organic carbon in soil

Abstract

A simple procedure is described for the rapid determination of organic carbon content in a large number of soil samples using an automated segmented flow analyser. The method is a modification of the wet oxidation/ digestion methods based on potassium dichromate combined with a colorimetric method for determination of chromic oxide (Stevenson and Clare, 1962). Using a segmented flow analyser for the colorimetry, the procedure is capable of automated routine analyses of large numbers of samples and was shown to give high and repeatable recoveries of organic carbon from a range of compounds. Organic carbon values for a range of soils analysed by the reported method and by the dry combustion technique showed a high correlation.     

A microscale method for colorimetric determination of urea in soil extracts

Abstract

The diacetyl monoxime colorimetric method of determining urea in soil extracts was modified for microplate format. A 100‐μL aliquot of extract was treated with color reagent in a disposable plastic microtiter plate (96 wells/plate), and color was developed by heating the plate in a low‐temperature oven at 87°C for 55 min. After cooling for 20 min at ambient temperature, absorbance measurements were simultaneously performed on all 96 wells using a microplate reader. The microscale method was faster and more convenient than the conventional method; moreover, the volume of waste was markedly reduced. Studies to compare the two methods showed very little difference in accuracy, precision, or sensitivity.