活化后钾改性正硅酸锂吸附CO2的性能评价及动力学研究

制备了钾改性正硅酸锂(K-Li4SiO4),并对其进行了自活化,考察了活化后K-Li4SiO4吸附剂在不同温度和CO2浓度气氛中吸附CO2的性能及动力学行为。总体而言,吸附剂的CO2吸附能力随着温度的升高、CO2浓度的增加而提升。在700℃、100%体积分数CO2气氛中吸附剂的吸附量最大,可达7.9 mmol/g,吸附剂的利用率为95.2%。利用双指数模型能够很好地描述吸附剂在各个温度以及各个CO2浓度气氛下的CO2吸附过程。吸附活化能随着CO2气氛浓度的升高而降低,CO2体积分数为20%,50%,100%时的吸附活化能分别为26448,14035,6178 J/mol。     

Enhanced adaptability of Sesbania rostrata to Pb/Zn tailings via stem modulation

Sesbania rostrata is renowned for its stem nodulation, but the role of stem nodulation in the root nodulation and adaptation of S.rostrata to Pb/Zn-enriched tailings environment has been poorly understood.We investigated the effects of inoculating (with stem nodule treatment) and non-inoculating (without stem nodule treatment) Azorhizobium caulinodans on the growth, root nodulation, and N fixation of S.rostrata grown on three different types of soil substrata: Pb/Zn tailings, garden soil amended tailings, and garden soil.The results showed that plant height, stem basal diameter, biomass, chlorophyll content, nitrogen content and N-accumulation per plant were 2.3%-4.9%, 2.2%-7.7%, 27.8%-72.2%, 17.1%-23.5%, 12.3%-34.2%, and 43.1%-131.2% higher in treatments with stem nodule than those without stem nodule for the same soil substrate, respectively.With respect to soil substrata, all the measurements had consistently higher values in tailings than in amended tailings and garden soil, indicating that the poorer the soil condition, the greater the contribution of stem nodule.In contrast, the number and fresh weight of root nodules on plants without stem nodule were 6.9-11.6 times and 5.8-29.0 times higher than those with stem nodule, respectively, especially with respect to the plants grew on Pb/Zn tailings.In general, stem nodulation favored plant growth and nitrogen fixation of S.rostrata, but suppressed root nodulation.With the ability of stem and root nodulation, S.rostrata can be used as a pioneer plant species for remediation of Pb/Zn tailings.     

上软下硬地层深基坑结构变形监测及分析*

为探究在上软下硬地层中进行深基坑开挖时围护结构水平位移与内支撑轴力的变化规律,以广州地区某上软下硬地层盾构井深基坑开挖项目为依托,基于现场监测数据进行分析并运用MIDAS/GTS软件开展深基坑开挖全过程的有限元模拟。将围护结构水平位移模拟值与监测值进行对比,验证模型的准确性;改变围护结构嵌固深度、主体结构厚度等工况,研究上述因素对结构水平位移变化产生的影响。研究结果表明:实测围护结构最大水平位移值11.78 mm,位于长边0.7倍基坑深度附近,坑角处位移值最小;改变结构嵌固深度对坑深15 m以下围护结构位移值影响较大,本工程最佳嵌固深度为1.5~3 m;围护结构水平位移会随着结构主体厚度的增加而减小,但最大位移间差值逐渐减小,结构主体厚度设计值宜为0.8~1 m。     

Heavy metal contamination in a vulnerable mangrove swamp in South China

Concentrations of six heavy metals (Cu, Ni, Zn, Cd, Cr, and Pb) in sediments and fine roots, thick roots, branches, and leaves of six mangrove plant species collected from the Futian mangrove forest, South China were measured. The results show that both the sediments and plants in Futian mangrove ecosystem are moderately contaminated by heavy metals, with the main contaminants being Zn and Cu. All investigated metals showed very similar distribution patterns in the sediments, implying that they had the same anthropogenic source(s). High accumulations of the heavy metals were observed in the root tissues, especially the fine roots, and much lower concentrations in the other organs. This indicates that the roots strongly immobilize the heavy metals and (hence) that mangrove plants possess mechanisms that limit the upward transport of heavy metals and exclude them from sensitive tissues. The growth performance of propagules and 6-month-old seedlings of Bruguiera gymnorhiza in the presence of contaminating Cu and Cd was also examined. The results show that this plant is not sufficiently sensitive to heavy metals after its propagule stage for its regeneration and growth to be significantly affected by heavy metal contamination in the Futian mangrove ecosystem. However, older mangrove seedlings appeared to be more metal-tolerant than the younger seedlings due to their more efficient exclusion mechanism. Thus, the effects of metal contamination on young seedlings should be assessed when evaluating the risks posed by heavy metals in an ecosystem.     

Identification of cadmium-induced genes in maize seedlings by suppression subtractive hybridization

A maize variety, Huatian-1, had an unusually low translocation rate of cadmium (Cd) (59.6 mg°kg⁻¹ in the roots and 0.093 mg°kg⁻¹ in the grain) compared to 24 other varieties while being grown in soils with 16.50 mg°kg⁻¹ Cd. This indicates that this particular species may have special mechanisms that affect the absorption and translocation pattern of Cd. In this paper, the technique of suppression subtractive hybridization (SSH) was used to isolate and identify Cd-induced genes from Huatian-1 hydroponically exposed to 0.1mM CdCl₂ for 1 h, 12 h, 24 h, and 48 h. We found a total of 15 differentially expressed genes in the four groups; 2, 3, 4, and 6 genes were from the groups of 1 h, 12 h, 24 h, and 48 h treatment, respectively. Phospholipase PLDb1 mRNA, adenosine triphosphate (ATP) phosphoribosyl transferase 2, and Sp17 were turned on in the maize in response to Cd stress, and it might provide new clues to explain the mechanism of maize tolerance to Cd.     

选择性吸附法处理含表面活性剂和多环芳烃的土壤淋洗液研究

比较研究了H103树脂、活性炭、沸石、硅藻土和膨润土等5种吸附剂对土壤淋洗液中TX-100与PAHs的吸附性能.批实验结果表明,H103树脂、活性炭、沸石、硅藻土和膨润土吸附后,淋洗液中T-PAHs及TX-100浓度分别为0.03和0 mg·L~(-1)、0.16和3623 mg·L~(-1)、15.21和6175 mg·L~(-1)、15.98和6555 mg·L~(-1)、9.49和4332 mg·L~(-1),选择性吸附系数排序依次为活性炭膨润土沸石硅藻土H103树脂.其中,活性炭能够去除淋洗液中99%的PAHs,同时保留51.33%的TX-100回收再利用,选择吸附系数达到109.5.活性炭固定床实验中,由淋洗液溶质的穿透曲线计算出物质的吸附容量.当空隙体积为2.5-7PV时,活性炭能够去除淋洗液中72%的PAHs,同时保留81%的TX-100,平均选择吸附系数为10.08.由此可见,活性炭固定床可有效处理含表面活性剂土壤淋洗液中的多环芳烃,同时实现表面活性剂的回收再利用.     

重金属在水体中的化学状态、危害及其防治对策

本文对目前研究最多的汞、铬、镉、铅和砷等重金属,详细分析了它们在水体中的迁移转化、价态变化、吸附与解吸附作用、吸附和共沉淀作用等动态过程;简要地阐述五种重金属对水体的污染给人体带来的危害;重点讨论了对水体重金属污染采取控制与消除土壤污染源、含重金属工业废水的排放和生物修复技术等防治对策。     

南昌市大气降水化学特征及来源分析

为分析南昌市大气降水离子来源和源区,对南昌市2016年4—9月大气降水样品主要阴阳离子的组成进行了测定分析,并运用PMF（正定矩阵因子分解）模型分析来源和TrajStat软件模拟后向轨迹.结果表明:NH₄+和Ca2+是南昌市大气降水中的主要阳离子,加权平均浓度为65.3和23.9 μmol/L,分别占阳离子总量的57%和21%;SO₄2-和NO₃-是主要阴离子,加权平均浓度为60.4和25.3 μmol/L,分别占阴离子总量的56%和23%.c（NH₄+）、c（Ca2+）、c（K+）、c（Mg2+）、c（Na+）、c（Cl-）、c（NO₃-）之间均存在着较为显著的相关性,说明它们之间可能有相似的来源或形成化合物共同存在.结合PMF模型分析结果表明,Na+、Cl-很明显受到了海盐的影响,也部分受土壤和二次污染影响;K+、Mg2+、Ca2+大部分来自于土壤,海盐、二次污染也贡献了一部分的K+;SO₄2-、NH₄+和NO₃-是组成大气二次颗粒物的主要成分,主要由二次污染源贡献;煤燃烧贡献了主要的F-和部分SO₄2-.后向轨迹模型分析表明,南昌市大气降水主要受局地降雨气团影响,5月、8月、9月受陆源及人为影响较大,海源性离子经过内陆上空时被稀释或沉降,导致6月、7月来自于海洋上空的降雨气团对南昌影响不大.研究显示,SO₄2-对南昌市大气降水的影响逐渐增大导致降雨类型逐渐由混合型向硫酸型转化,人为影响是造成大气污染的主要原因.      

δ13C and fatty acid composition of mesopelagic fishes in the South China Sea and their influence factors

Study of the ecology of mesopelagic fishes is central for assessing the active biological pump in the ocean, especially in the mesopelagic layers. The use of δ¹³C and fatty acid analysis can help to analysis the ecology of mesopelagic fishes. Here, we analysed the fatty acid composition of mesopelagic fishes from the continental northern slope of the South China Sea (NSSCS) and compared with nearshore SCS fishes and mesopelagic fishes collected from the Southern Ocean. The mesopelagic fishes had unusually high lipids, which resulted in Δδ¹³C values exceeding 1‰, more than the enrichment factor in the food web. The mesopelagic fishes had higher C18:1n-9/C18:1n-7 and C20:1n-9/ C18:1n-7 ratios compared with other fishes in the SCS, which confirmed that plankton were their main dietary source. The mesopelagic fishes from SCS and Southern Ocean had different ratios of C20:5n-3/C22:6n-3 (EPA/DHA), suggesting geographical locations and diet sources had obvious influence on their fatty acid composition. The SCS mesopelagic fishes had higher C20:4n-6/C22:6n-3 (ARA/DHA) and C20:4n-6/C20:5n-3 (ARA/EPA) ratios than mesopelagic fishes in the Southern Ocean, indicating the influence of physical factors on fatty acid composition. Thus, future studies of the fatty acids in mesopelagic fishes should consider both dietary sources and physical environments.     

Genotype variations in accumulation of cadmium and lead in celery (Apium graveolens L.) and screening for low Cd and Pb accumulative cultivars

To help reduce risks of heavy metal pollution, two pot experiments were conducted to investigate the variations, transfer potential, and stability of Cadmium (Cd) and Lead (Pb) accumulations in celery (Apium graveolens L.) and to screen for low Cd and Pb accumulative cultivars. The maximum differences in shoot Cd concentration were 4.7-fold under low-Cd exposure and 3.3-fold under high-Cd exposure. These genotype variations in Cd accumulation are sufficiently large to help reduce Cd contamination risk in soil by using the Low-Cd-Accumulative genotypes. Cd accumulation of the Low-Cd-Accumulative genotypes is significantly positive correlated with Pb accumulation. Evidence obtained proves that Cd and Pb accumulations in celery are stable and genotype-dependent at the cultivar level. The presence of high-Pb contamination in soil promoted Cd accumulation in shoots of celery. Celery is considered a species with high risks in Cd pollution and low risks in Pb pollution. Among the tested cultivars, cv. Shuanggangkangbing (SGKB) had the lowest shoot Cd and Pb accumulating abilities, and thus is the most important material for breeding of pollution-safe cultivars (PSCs) to minimize Cd and Pb accumulations in celery.