A study of the elemental leachability and retention capability of compost

In this work a comparison is made between the different approaches that can be taken to evaluate the mobility of elements in compost. The practical consequences of the results obtained are also discussed in terms of methods for cleaning up compost and using compost in environmental remediation. The mobility of potentially toxic elements in compost is evaluated by leaching with four selected eluents, i.e. diluted sulfuric acid, oxalate, citrate and EDTA. In contrast to the chelating agents, diluted sulfuric acid was found to generally have a low leaching capability for removal of heavy metals from compost. This implies that the risk of heavy metal leaching caused by natural rainfall is likely to be low. The results obtained in the leaching experiment were compared with previous results obtained from sequential fractionation. This comparison confirmed that both methods gave similar results for predicting the lability of elements in compost. A non-linear regression analysis of the leaching curves was also conducted. The leaching curves for elements with high lability could be fitted with a two components model. The labile components identified by the kinetic model are approximately in accordance with the fractions obtained from the first step of the sequential extraction method. The kinetic speciation method is shown to be a relatively rapid and simple procedure for compost which gives more information about element lability than simple leaching experiments. The leaching reagents used in this work were not effective enough to be used for cleaning up compost with a high metal content. Compost was however shown to have a high affinity for heavy metals, with the order of affinity of metal for the compost being very similar to that seen for humic acid. Compost may therefore prove to be a good remediation material for metal contaminated waste.     

醇胺溶液吸收与解吸CO2的研究

在温度333K、常压条件下,在羟乙基乙二胺(AEE)总量一定的溶液中,研究了不同浓度AEE对CO2的吸收性能;在总胺质量分数为40%的溶液中,研究了不同配比的AEE N-甲基二乙醇胺(MDEA)对CO2的吸收性能.考察了吸收过程中吸收速率、吸收量、吸收时间、AEE浓度以及吸收液温度的相互关系.控制解吸过程温度为393K,考察了CO2解吸量与解吸时间的关系.实验表明,适当降低AEE浓度有利于充分发挥AEE溶液的CO2吸收性能;在MDEA溶液中加入适量AEE,可以明显提高CO2的吸收与解吸性能;其中质量分数为20?E 20%MDEA的复合溶液在CO2吸收与解吸过程中表现出良好的实际操作性.     

真空紫外光降解苯的研究

为了考察真空紫外光辐射在气体净化中的应用,以苯作为目标污染物,分别进行了紫外光波长、气体湿度、反应时间、初始浓度以及辐射功率对苯光解率的影响实验。实验结果表明,真空紫外光辐射方法净化气相污染物中的苯效果良好,在一定条件下,浓度为348.2 mg/m³苯污染气体真空紫外光降解率可达到90%。通过在不同条件下苯的降解率以及臭氧浓度变化,初步探讨了苯降解的机理以及降解途径。苯的降解主要是通过氢氧自由基（·OH）的加成以及后续一系列的氧化反应,降解产物为苯酚以及含有羟基的长链烃。     

反硝化除磷菌驯化富集方式的探讨

以SBR反应器分别采用一段式和二段式培养方法对反硝化除磷菌进行了驯化富集.结果表明,一段式和二段式培养方法驯化完成后的活性污泥沉降性能均较好,污泥体积指数(SVI)分别约为60、50 mL/g,反硝化除磷菌占聚磷菌的比例达到了77%和71%.两种培养方法下反硝化除磷菌PO3-4-P去除率和脱氮率分别达到了97%和95%以上,缺氧结束时水中PO3-4-P质量浓度小于1 mg/L.驯化完成后污泥的含磷率最高达到了3.7%(质量分数).因此,采用一段式或二段式驯化方法均能实现反硝化除磷菌的有效富集.     

Changes of organic acid exudation and rhizosphere pH in rice plants under chromium stress.

The effect of chromium (Cr) stress on the changes of rhizosphere pH, organic acid exudation, and Cr accumulation in plants was studied using two rice genotypes differing in grain Cr accumulation. The results showed that rhizosphere pH increased with increasing level of Cr in the culture solution and with an extended time of Cr exposure. Among the six organic acids examined in this experiment, oxalic and malic acid contents were relatively higher, and had a significant positive correlation with the rhizosphere pH, indicating that they play an important role in changing rhizosphere pH. The Cr content in roots was significantly higher than that in stems and leaves. Cr accumulation in plants was significantly and positively correlated with rhizosphere pH, and the exudation of oxalic, malic and citric acids, suggesting that an increase in rhizosphere pH, and exudation of oxalic, malic and citric acid enhances Cr accumulation in rice plants.     

Indoor and outdoor radon measurements at lung cancer patients’ homes in the dwellings of Rize Province in Turkey

In this study, indoor and outdoor radon (²²²Rn) surveys were carried out in the summer and winter seasons in homes of one hundred lung cancer patients in the year 2013–2014. The aim was to investigate the relationship between radon and cancer patients. Lung cancer patients completed a questionnaire concerning their living environment, various physical parameters and living habits. Pearson correlation and t tests revealed no meaningful results between radon concentrations, on one hand, and environmental and personal living habits, on the other hand. Consequently, the BEIR VI model was adapted and ²²²Rn exposure was estimated to be responsible for about 12% of the lung cancer incidences in the winter season and around 5% in the summer season in the Rize Province. However, due to the limited number of data and numerous parameters that could lead to lung cancer, the estimations done with the model should be taken very lightly. The annual effective doses due to inhalation of indoor and outdoor ²²²Rn were estimated to be, respectively, 1.43 and 0.94 mSv y^?1. The indoor and outdoor annual effective doses were, respectively, close and below the world annual effective dose (1.3 mSv y^?1). At the district level, the indoor annual effective dose equivalent in the ?yidere district was 4.52 mSv y^?1, which was 3.5 times greater than the world average. The number of patients in the majority of the houses in this district was more than one.     

An extraction-assay system: Evaluation on flavonols in plant resistance to Pb and Cd by supercritical extraction-gas chromatography

In this research, supercritical carbon dioxide extraction (SFE) showed better extraction effect when compared with Solid- liquid extraction (SLE), Soxhlet extraction (SE) and Ultrasonic extraction (UE), not only in the rate but also the time. The comparison among these three extraction modifiers, including acetone, ethanol and methanol demonstrated that ethanol was preferred to SFE due to its high extraction effect and low toxicology. In addition, parameter of SFE, influence of temperature and pressure were investigated, and the best extraction effect was achieved at the optima conditions, temperature of 40°C and the pressure of 35 MPa. Thus, SFE is a highly effective method for flavonols extraction, requiring minimum energy and producing non-toxic byproduct. SFE-GC system is applied for the evaluation on flavonols that plays a key role in plant resistance to heavy metal, with its content and synthetase gene expression significantly increasing in plant when threatened by heavy metal. Besides, results indicated that flavonols can improve plant resistance to oxidative stress by quenching the redundant ROS in matrix.

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应用鱼类生物完整性指数评价荔浦河河流健康

生物完整性指数是河流生态系统健康评价主要方法之一。为评价荔浦河河流健康状况,选择鱼类作为指示生物,构建了基于鱼类生物完整性指标体系。2017年1月、4月、7月和10月对荔浦河4次采样共采集到鱼类21 192尾,经鉴定共计94种,隶属于6目17科62属。以S1(修仁镇)、S10(马岭镇)、S11(双江镇)作为参考点,经过分布范围分析、箱体图判别能力分析及相关性分析等指标筛选过程从25个候选指标筛选出5个指标,即鱼类总物种数、Shannon-Wiener多样性指数、肉食性鱼类数量百分比、敏感性鱼类数量百分比、产漂浮型卵鱼类数量百分比。将荔浦河河流健康等级分为"健康"、"一般"、"较差"、"极差"和"无鱼"5个等级。结果表明,荔浦河青山镇、荔浦县及蒲芦乡河段健康状态为"一般"水平,东昌镇、龙怀乡、杜莫镇及新坪镇河段健康状态为"较差"水平,茶城乡河段健康状态为"极差"水平。筑坝工程、架桥工程和修路工程等人类活动导致荔浦河支流上的健康状况比干流更差。上述研究结果可为荔浦河的河流管理和保护提供理论依据和技术支持。     

磺胺类化合物对大肠杆菌突变QSAR预测模型初探

抗生素被广泛应用于医疗、农业和畜牧业等领域,但是长期滥用会促进细菌的突变作用。本文以大肠杆菌(E.coli)为受试生物,测定了10种磺胺类抗生素(SAs)单一暴露时对E.coli的突变效应,采用物化参数Ebinding(抗生素与其靶蛋白的相互作用能力)与突变效应参数lgRC0-2(最高可观测突变促进效应浓度)或lgRCmax(突变促进率最大值对应的浓度),建立了突变效应的QSAR模型,并采用雷达图进行验证。结果表明,lgRC0-2与Ebinding模型和lgRCmax与Ebinding、DMG(偶极矩)模型的拟合系数R2分别是0.888、0.873,即lgRC0-2或lgRCmax与Ebinding相关性均较好,可能由于磺胺类化合物(SAs)会作用于叶酸合成通路,影响嘌呤、嘧啶碱基的合成,从而对E.coli的突变具有促进效应,且雷达图验证表明,上述2个模型均具有良好的内部预测能力。本研究有望为抗生素使用带来的生态风险评价以及药物设计提供相关指导。     

Metals and metalloids in PM10 in Nandan County,Guangxi, China,and the health risks posed

Intense mining, smelting, and tailing activities of polymetallic ore deposits have affected the environment in Nandan County, Guangxi, China. Samples of particulates with aerodynamic diameters low or equal 10 μm (PM₁₀) were collected in Nandan County to investigate the concentrations of and health risks posed by 17 metals and metalloids in the PM₁₀. The metal and metalloid concentrations were lower than those found in other industrial cities. The mean Cr concentration was 7.48 ng/m³. Significant higher metal and metalloid concentrations were found in PM₁₀ from mining areas (Dachang and Chehe) than from the control area (Liuzhai) (p < 0.05). Principal component analysis indicated that the main sources of Ba, Co, Cr, Fe, K, Mg, Mo, Na, and Sr were resuspension of the soil produced through mineral erosion, the main sources of As, Cd, Cu, Pb, Sb, and Zn were smelting and mining activities, and the main source of Ni was fossil fuel combustion. Higher non-carcinogenic and carcinogenic risks were posed in Dachang and Chehe than in Liuzhai. The non-carcinogenic risks posed to adults and children by individual metals and metalloids in PM₁₀ at all the sites were low, but the non-carcinogenic risks posed to children by all the metals and metalloids together exceeded the safe level (i.e., risk value > 1). The carcinogenic risks posed by Cd, Ni, and Pb were negligible at all sites, while As, Co, and Cr posed potential carcinogenic risks to the residents.