The negative effects of cadmium on Bermuda grass growth might be offset by submergence

Revegetation in the water-level-fluctuation zone (WLFZ) could stabilize riverbanks, maintain local biodiversity, and improve reservoir water quality in the Three Gorges Reservoir Region (TGRR). However, submergence and cadmium (Cd) may seriously affect the survival of transplantations. Bermuda grass (Cynodon dactylon) is a stoloniferous and rhizomatous prostrate weed displaying high growth rate. A previous study has demonstrated that Bermuda grass can tolerate deep submergence and Cd stress, respectively. In the present study, we further analyzed physiological responses of Bermuda grass induced by Cd-and-submergence stress. The ultimate goal was to explore the possibility of using Bermuda grass for revegetation in the WLFZ of China’s TGRR and other riparian areas. The Cd-and-submergence-treated plants had higher malondialdehyde contents and peroxidase than control, and both increased with the Cd concentration increase. All treated plants catalase activity increased with the experimental duration increases, and their superoxide dismutase also gradually increased with the Cd concentration from 1 day to 15 days. Total biomass of the same Cd-and-submergence plants increased along the experimental duration as well. Plants exposed to Cd-and-submergence stress showed shoot elongation. The heights of all treated plants were taller than those of the control. Leaf chlorophyll contents, maximum leaf length, and soluble sugars contents of all the Cd-and-submergence-treated plants were more than those of the untreated control. Although Cd inhibits plants growth, decreases chlorophyll and biomass content, and with the submergence induced the leaf and shoot elongation, more part of the Cd-and-submergence stress plants appeared in the air, exhibited fast growth with maintenance of leaf color, which guaranteed the plants’ photosynthesis, and ensured the total biomass and carbohydrate sustainability, further promoting Cd-and-submergence tolerance. The results imply that the negative effects of cadmium on Bermuda grass growth might be offset by submergence.     

粉煤灰两步水热法制备人工沸石

以粉煤灰为原料,采用两步水热法制备人工沸石。SEM、XRD、X射线荧光光谱分析结果表明:制得的人工沸石纯度较高,主要为Na-A型沸石和少量13X型沸石,主要化学成分为SiO2和Al2O3。说明采用两步法制备人工沸石克服了传统水热法杂质含量高的缺陷。采用人工沸石处理初始Mn2+质量浓度为50.00mg/L的模拟含锰废水,吸附125min后,Mn2+去除率达98.19%,模拟废水中剩余Mn2+质量浓度为0.90mg/L。     

钛铁矿造孔核桃壳基活性炭的制备及其吸附性能

以核桃壳为原料,钛铁矿为造孔剂,制备钛铁矿造孔核桃壳基活性炭。实验结果表明：在氯化锌浓度为3mol/L、碳化时间为40min、碳化温度为400℃、钛铁矿加入量为5%的条件下,制得的钛铁矿造孔核桃壳基活性炭对苯酚、碱性品红、Pb²⁺的吸附量分别达到了156.80,181.35,35.84mg/g,比核桃壳活性炭分别提高了25.84%,18.59%,19.10%;钛铁矿作为造孔剂制备活性炭,可以降低碳化温度和缩短碳化时间,且对活性炭中孔的形成起促进作用,有利于对大分子物质和重金属的吸附去除。     

百菌清农药残留的SPE-GC检测

对环境水样中百菌清农药残留进行了SPE-GC分析方法研究。环境水样通过Florisil柱富集、净化,3 mL乙酸乙酯洗脱,GC-ECD进行分析检测。实验表明,百菌清农药残留在0.01~10 mg/L范围内线性关系良好,相关系数为0.9993。外标法定量,检出限为0.0035 mg/L,对实际水样进行加标回收,回收率范围在93.47%~100.14%之间,6次重复测定相对标准偏差在3.97%~4.96%之间,并将方法应用于周边环境地表水的检测。该方法具有简便,快速,准确,灵敏度高等特点,能满足环境水样中农药残留分析要求。     

废旧混凝土用作水泥稳定基层的实验研究

随着城市建设的发展,城市道路改建时产生的大量的废弃混凝土块的有效利用成了一个亟待解决的问题。结合宜昌市东山大道改建项目,将废弃的混凝土面板加工形成再生集料用作水泥稳定碎石基层,达到节约资源和保护环境的目的。实验分析了再生集料的颗粒级配、压碎值、针片状颗粒含量、表观密度和吸水率等工程性质指标,同时对水泥稳定再生碎石的级配、最佳水泥掺量进行了设计,并对水泥稳定再生碎石的无侧限抗压强度指标进行了研究。研究表明,废旧混凝土经加工形成的再生集料具有良好的路用性能,其颗粒级配、压碎值以及主要指标均达到了路面基层材料的要求;掺3%、5%和7%水泥稳定再生集料7 d浸水抗压强度均达到路面基层的要求,水泥稳定再生集料用作路面基层是可行的;掺3%水泥稳定的再生集料可以用在公路的底基层,掺5%及7%水泥稳定的再生集料可以分别用作路面下基层和上基层。     

The potential of the flora from different regions of Pakistan in phytoremediation: a review

Soil and water quality is greatly affected by environmental pollution due to the increasing trend of urbanization and industrialization. In many developing countries, including Pakistan, the situation is more alarming as no preventive measures are still taken to tackle the problem. Although in developed countries, many techniques are used to remediate the environment including phytoremediation. It is the most eco-friendly technique in which plants are used to remove pollutants from the environment. Pakistan has also a great diversity of plants which could be used for the remediation of environmental pollutants. To our knowledge, few studies from Pakistan were reported about the use of flora for phytoremediation. According to recent literature, 50 plant species from Pakistan are studied for remediation purposes. In this review, the potential of different plant species for phytoremediation from Pakistan has been discussed along with their comparison to other countries to relate future perspectives.     

The challenges of reducing greenhouse gas emissions and air pollution through energy sources: evidence from a panel of developed countries

The objective of the study is to investigate the long-run relationship between climatic factors (i.e., greenhouse gas emissions, agricultural methane emissions, and industrial nitrous oxide emission), air pollution (i.e., carbon dioxide emissions), and energy sources (i.e., nuclear energy; oil, gas, and coal energy; and fossil fuel energy) in the panel of 35 developed countries (including EU-15, new EU member states, G-7, and other countries) over a period of 1975–2012. In order to achieve this objective, the present study uses sophisticated panel econometric techniques including panel cointegration, panel fully modified OLS (FMOLS), and dynamic OLS (DOLS). The results show that there is a long-run relationship between the variables. Nuclear energy reduces greenhouse gases and carbon emissions; however, the other emissions, i.e., agricultural methane emissions and industrial nitrous oxide, are still to increase during the study period. Electricity production from oil, gas, and coal sources increases the greenhouse gases and carbon emissions; however, the intensity to increase emissions is far less than the intensity to increase emissions through fossil fuel. Policies that reduce emissions of greenhouse gases can simultaneously alter emissions of conventional pollutants that have deleterious effects on human health and the environment.     

Temporal variations of benthic diatom community and its main influencing factors in a subtropical river, China

Benthic diatoms are the main component in many aquatic ecosystems such as streams, creeks and rivers, and they function as important primary producers and chemical modulators for other organisms in the ecosystems. In this study, the composition of benthic diatoms was investigated and further explored the primary physicals and chemicals affecting their temporal variations in the upper Han River, China. There were seasonal variations in physical and chemical variables in waters over the sampling period of 2007–2010. Water temperature (t), chemical oxygen demand, total nitrogen, dissolved organic carbon (DOC), silica and fluoride were much higher in the high flow season (i.e., July or August) than these in the base flow season. Three species Achnanthidium minutissimum (composed of 10.7 % of the total diatom abundance), Achnanthidium pyrenaicum (11.9 %), and Achnanthidium subatomus (12.7 %) accounting for more than 5 % of the total diatom abundance were persistently dominant in all seasons, while the other two prostrate and motile species including Eolimna minima and Nitzschia dissipata also dominant in the base flow season. The species richness always peaked in autumn with significant difference with summer (p?<?0.01), and density of benthic diatom varied and peaked in April. Analyses indicated that the temporal variation in benthic diatom communities was strongly related to t, nitrogen, organic pollutants (indicated by COD and DOC), and hydrological regime. The research will expand the understanding of water chemistry monitoring, and improve watershed- scale management and conservation efforts in the upper Han River, China.     

Variation of Microcystis and microcystins coupling nitrogen and phosphorus nutrients in Lake Erhai,a drinking-water source in Southwest Plateau,China

Lake Erhai is the second largest lake of Southwest China and an important drinking water source. The lake is currently defined as the preliminary stage of eutrophic states, but facing a serious threat with transfer into intensive eutrophication. The present study examined the dynamics of Microcystis blooms and toxic Microcystis in Lake Erhai during 2010, based on quantitative real-time PCR method using 16S rRNA gene specific for Microcystis and microcystin systhesis gene (mcy), and chemical analysis on microcystin (MC) concentrations. Total Microcystis cell abundance at 16 sampling sites were shown as an average of 1.7?×?10⁷ cells l^?1 (1.3?×?10²–3.8?×?10⁹ cells l^?1). Microcystin LR (MC-LR) and microcystin RR (MC-RR) were the main variants. The strong southwesterly winds, anticlockwise circular flows and geographical characteristics of lake and phytoplankton community succession impacted the distribution patterns of Chl a and MC in the lake. The concentration of Chl a and MC and abundances of total Microsytis and MC-producing Microsystis (MCM) were shown to be positively correlated with pH, DO and TP, negatively correlated with SD, NO₃-N, TN/Chl a and TN/TP, and not correlated with NH₄-N, TN, dissolved total nitrogen (DTN) and water temperatures. When TN/TP decrease, Microcystis tended to dominate and MC concentrations tended to increase, suggesting that the “TN/TP rule” can be partially applied to explain the correlation between the cyanobacterial blooms and nutrients N and P only within a certain nutrient level. It is speculated that N and P nutrients and the associated genes (e.g., mcy) may jointly drive MC concentration and toxigenicity of Microcystis in Lake Erhai.     

煤基腐殖酸对外源砷胁迫下玉米生长及生理性状的影响

为了筛选用于砷污染土壤治理的煤基腐殖酸,采用盆栽实验研究了施用不同种类和浓度的煤基腐殖酸及EDTA对外源砷胁迫下玉米株高、株鲜重、株干重、根干重、砷积累量、叶片抗氧化酶（POD,SOD和CAT）活性和脯氨酸含量的影响。结果表明,11种供试煤基腐殖酸均促进了玉米生长,提高了叶片POD、SOD和CAT活性。其中6和10号腐殖酸可降低土壤砷活性和显著抑制玉米吸收和积累砷,而8和9号腐殖酸增加了土壤活性砷和显著促进了玉米对砷的吸收和累积,且不同程度地强于EDTA。除8和9号外,其余腐殖酸均可明显降低玉米叶片脯氨酸的含量。EDTA可显著促进玉米吸收和积累砷,且加剧了砷对玉米的危害。因此,8和9号供试煤基腐殖酸可以替代EDTA活化土壤砷,与植物配合以提高砷污染土壤的植物修复速度和效果,而6和10号供试煤基腐殖酸则可用于土壤砷钝化剂,以保证作物产品的安全。