钝化剂对中碱性农田土壤重金属镉及其在小麦中累积的影响

通过田间实验探讨了钝化剂对中碱性农田土壤中镉含量及其在小麦不同生长期镉累积的影响。结果显示,钝化剂能降低中碱性农田土壤有效态镉含量。在有效态镉含量为1.24 mg·kg^(-1)的新乡农田土壤中,添加w=0.20%的钝化剂,60~240 d后土壤二乙烯三胺五乙酸(DTPA)有效态镉含量较对照(CK)降低28.09%~53.15%,140 d后小麦根、茎、叶镉含量较对照分别降低43.20%、53.00%、53.00%,200 d后分别降低48.92%、53.82%、39.20%,240 d后分别降低47.92%、29.46%、21.41%,说明钝化剂能降低土壤中有效态镉含量和小麦中镉含量,使小麦不同生长期各部位镉累积量降低,小麦籽粒镉含量从0.22降低至0.09 mg·kg^(-1),满足GB 2762—2017《食品安全国家标准食品中污染物限量》要求。

含硫材料对中碱性农田土壤镉的钝化效果

通过模拟实验探讨含硫材料〔硫化钙(CaS)、聚合二硫代氨基甲酸钠(DTCR)和2,4,6-三巯基均三嗪三钠(TMT)〕对中碱性农田土壤中镉的钝化效果。结果显示,相同试验条件下,在2种麦田土壤(来自河南新乡和济源)中,3种钝化剂对DTPA有效态镉降低效率的大小顺序均为TMT55(纯度w为55%)>DTCR>CaS。在有效态镉含量为1.56 mg·kg^-1的新乡土壤中添加w=0.10%的CaS、DTCR和TMT55,稳定30 d后有效态镉含量分别比对照降低21.15%、48.71%和41.69%。在有效态镉含量为0.97 mg·kg^-1的济源土壤中添加w=0.10%的CaS、DTCR和TMT55,稳定30 d后有效态镉含量分别比对照降低10.42%、40.43%和40.70%。与其他材料相比,DTCR和TMT55具有低剂量和高效率的优点,是潜在的中碱性农田土壤重金属镉修复材料。

钝化剂对冶炼厂周边中碱性农田土壤重金属及其在小麦中累积的影响

通过冶炼厂周边田间试验,探讨了钝化剂2,4,6-三巯基均三嗪三钠(TMT)对冶炼厂周边中碱性农田中小麦生长末期重金属累积的影响。结果显示:在污染土壤中,添加w=0.10%(质量分数)TMT55材料,60~240 d后土壤DTPA有效态镉含量较对照降低效率为18.50%~41.53%;DTPA有效态铅含量较对照降低效率为21.06%~28.43%。在有效态镉含量为0.97 mg/kg的污染土壤中添加w=0.10%(质量分数)TMT55材料,200 d后小麦根、茎、叶镉含量较对照分别降低32.04%、27.38%、35.39%,240 d后小麦根、茎、叶、籽粒镉含量较对照分别降低18.12%、34.86%、12.39%、20.81%。在有效态铅含量为56.72 mg/kg的污染土壤中添加w=0.10%(质量分数)TMT55材料,200 d后小麦根、茎、叶铅含量较对照分别降低26.84%、23.84%、29.32%,240 d后小麦根、茎、叶、籽粒铅含量较对照分别降低14.34%、46.36%、19.29%、42.40%。TMT55材料能抑制小麦在生长末期对重金属镉和铅的累积,是潜在重金属污染的冶炼厂周边中碱性农田土壤修复材料。

混凝土及钢筋混凝土腐蚀与耐久性浅谈

简要论述了砼及钢筋砼在较为典型的中碱性及滨海盐土中的腐蚀特征、机理，并提出了在这两类土壤中混凝土的防护措施及配合比设计时应注意的问题，旨在使混凝土的耐久性问题能得到广泛关注。

怎样防治向日葵列当

列当,也叫独根草,俗称兔子拐棍,是危害向日葵的一年生寄生杂草,分布很广,危害严重。一、形态特征列当可分为分枝和不分枝两种,它没有叶绿素,不能进行光合作用,也没有真正的根,不能自养。茎直立,单生,肉质,淡黄色或紫色,株高一般在40厘米左右。列当适于中碱性土壤上生长,PH值低于6.5的酸性土壤上很少见到这一类植物。列当从种子出苗到形成新的种子需要22～33天,其中从种子出苗到开花需要4～11天,从开花到结实需要5～7天,

中碱性镉污染农田原位钝化修复材料研究进展

农田土壤重金属污染威胁人类健康,其修复成为环境领域的研究热点。钝化修复因具有修复速率快、成本低、操作简单、不影响农业生产等特点,广泛应用于大面积重金属污染农田尤其是酸性农田修复治理中。相应,针对酸性重金属污染土壤的钝化修复材料也得到了广泛研究,然而,针对中碱性重金属污染土壤的钝化材料研究相对较少。从无机类、有机类以及复合型3种类型的修复材料概述了钝化修复材料在中碱性Cd污染土壤中的研究进展。总结了中碱性重金属污染土壤钝化修复材料以选用复合型材料为宜,且以钙镁磷肥、椰壳生物炭、油菜秸秆生物炭、腐殖酸形成有机-无机复合效果较好且经济环保。其次,从钝化剂的合理施用、风险评估等方面提出展望,以期为中碱性农田土壤重金属污染修复提供参考。

Application of nitrogen-fixing cyanobacteria in restoration of saline and alkaline soils of Songnen Plain in China

The salt-resistant nitrogen-fixing cyanobacteria 888 was experimentally applied to the reclamation of saline and alkali soil in Songnen Plain in China. The pH, electrical conductivity (EC) and sodium adsorption ratio (SAR) of different saline soils were studied and compared. Results show that different saline soils exhibit various physico-chemical properties. Saline-sodic soils in Songnen Plain are ameliorated by using nitrogen-fixing blue-green algae 888 in the experiment. It is indicated that cyanobacteria 888 can grow in saline and alkaline soils, and the conditions favorable for its growth are soil moisture of 50% and dry algae inoculation at 0.03 mg/cm2. The main actions of nitrogen-fixing cyanobacteria are keeping the adsorbability of rubber sheath for sodium, increasing the organic matter content of the soils and decreasing the pH and the degree of salinity in the soils. But the arid climate and soil depth are the main factors that limit the restoration of saline and alkaline soils.

Modeling Cadmium Transport in Neutral and Alkaline Soil Columns at Various Depths

Human health has been potentially threatened by cadmium (Cd) contained in sewage irrigation water.Previous studies of Cd transport in soils were mainly conducted using small soil cores with pH values less than 6.The objectives of this study were to determine the parameters of the convection-dispersion equation (CDE) for Cd transport in relatively larger columns with neutral and alkaline soils,and to investigate the parameters' variability with depth.The soil columns were 50 cm in length and 12.5 cm in diameter.Ceramic suction lysimeters were buried at depths of 2.5,7.5,17.5,27.5,and 37.5 cm to abstract soil solution.Cd concentration in the soil solution samples were subsequently analyzed to obtain breakthrough curves (BTCs).Equilibrium and nonequilibrium models in CXTFIT program were used to estimate parameters of the CDE.The results suggested that both equilibrium and non-equilibrium models performed well in modeling Cd transport.The hydrodynamic dispersion coefficient (D) ranged from 0.18 to 10.70 cm 2 h 1,showing large differences among different depths.The retardation factor (R d) ranged from 25.4 to 54.7 and the standard deviation of R d value was lower than 30% of the mean value.Precipitation coefficient (R p) decreased consistently with increasing depth,varying from 1.000 × 10 10 to 0.661 h 1.Sensitivity tests showed that D was less sensitive than R d.These results would be helpful in understanding the transport and retention of Cd in non-acidic soils.