Uptake and concentration of heavy metals in dominant mangrove species from Hainan Island,South China

Environmental Geochemistry and Health - By investigating three dominant mangrove species, namely Aegiceras corniculatum, Kandelia candel, Ceriops tagal and their rhizosediment in Mangrove wetlands...     

Research progress and hot spots of hydrothermal liquefaction for bio-oil production based on bibliometric analysis

Environmental Science and Pollution Research - Hydrothermal liquefaction (HTL) of biomass used HTL reaction under high temperature and pressure to produce bio-oil. This technology is considered as...     

我国海岸侵蚀灾害及对策

文章通过大量实际资料展现了我国海岸侵蚀灾害的严重性;从入海泥沙、人类活动、地面沉降、海岸特性、海平面上升等方面分析了造成海岸侵蚀的原因;提出了一系列防治海岸侵蚀灾害的对策。     

A joint use of life cycle assessment and emergy analysis for sustainability evaluation of an intensive agro-system in China

Environment, Development and Sustainability - Sustainability assessing on agricultural production systems has developed rapidly over the last two decades, and various models are formulated from...     

滆湖水华初期浮游植物群落特征及与水环境因子相关性分析

为探究滆湖水华初期浮游植物群落特征及与水环境因子的相关性,于2018年5—7月在全湖布设22个点,调查研究滆湖水华初期浮游植物群落时空分布特征,并对引起水华主导环境因子进行分析.结果表明：①共获得7门119属,优势属为绿藻门的小球藻与球团藻、蓝藻门的鞘丝藻与微囊藻,其中湖心区域浮游植物丰度与多样性小,均匀性低,属于中偏重污染区域;湖北区以北属于中污染区域,蓝藻堆积严重;西部沿岸及南端区域属于中偏轻污染区域.②冗余分析得出,湖心藻类与水温（T）有强相关性,与叶绿素a（Chl-a）、溶解性总磷（DTP）、pH、溶解氧（DO）呈一定正相关性;湖北区以北藻类与底泥有机质（OM）、水体悬浮物（SS）、Chl-a及DTP呈强相关性,与T呈一定相关性.T与多项环境因子相关,均值从26.1℃上升到32.4℃;OM与有机磷（OP）呈高度相关性（p<0.05,r=0.892）.水华发生的主导环境因子为T、DTP与pH,底泥OM及OP有一定影响.     

基于AIS轨迹修复的船舶排放空间表征改进方法与应用

基于船舶自动识别系统（Automatic Identification System,AIS）数据表征船舶排放是目前船舶排放空间表征的主流方法,但AIS船舶轨迹点缺失会造成船舶排放量低估和船舶空间分布表征错误,进而影响船舶排放控制区的划分.为改进船舶排放空间表征,本研究以2013年广东省AIS船舶数据为例,采用基于时间和经纬度的三次样条方法对AIS船舶轨迹进行修复,结合动力法计算船舶排放,分析对比AIS轨迹修复前后船舶排放表征的差异,并利用空气质量模型和卫星观测评估AIS轨迹修复对船舶排放表征和广东沿海空气质量模拟的改进效果.结果表明：轨迹修复后广东省海域船舶轨迹点总数由4685773个增至5746664个,船舶NO_x排放量增加了0.6%.对于轨迹点与排放缺失集中的粤东海域,轨迹修复后船舶轨迹点数增加了88%,NO_x排放量在广东省船舶排放量的占比提升至22%,特别是在粤东重点修复海域NO_x排放量增加了2.7倍.原始轨迹在广东省海域较为稀疏,在粤东海域有明显轨迹缺失;轨迹修复后广东省海域船舶轨迹更为密集,粤东海域船舶轨迹得以补充,船舶排放空间分布更连贯.对比模拟结果与卫星观测结果,轨迹修复后粤东重点修复海域船舶模拟浓度与观测浓度的偏差由51%减至6%,总体上船舶排放模拟结果更接近卫星观测结果.     

陕北不同沟道土地盐碱化现状及影响因素

沟道土地是陕北黄土丘陵沟壑区重要的土地资源。然而,当前对黄土高原沟道土地的盐碱化问题关注不够,对盐碱化的现状、发生机制和防治措施也缺乏深入系统的认识,知识储备不能满足生产实际的需要。本文以陕北黄土丘陵沟壑区自然和人为形成的沟道土地为研究对象,分别是延安顾屯新造耕地(治沟造地)、延川马家湾淤地坝土地和子洲黄土洼天然古聚湫土地,在这些流域内沿沟道采集土壤样品,测定土壤的电导率(EC)、p H值、含水量及粒度,分析土壤盐碱化的现状和影响因子。结果表明:马家湾淤地坝土地盐碱化最为严重,流域中游至上游均出现不同程度的盐碱化;顾屯新造地上游出现盐碱化,盐碱化程度较马家湾轻,而黄土洼古聚湫全流域未出现盐碱化。地下水位较浅是沟道土地发生盐碱化的主要影响因素,因此陕北沟道土地盐碱化防治应着力控制地下水位,建设良好的排水系统,加强排水。     

Regulated emission characteristics of in-use LNG and diesel semi-trailer towing vehicles under real driving conditions using PEMS

On-road driving emissions of six liquefied natural gas(LNG) and diesel semi-trailer towing vehicles(STTVs) which met China Emission Standard IV and V were tested using Portable Emission Measurement System(PEMS) in northern China.Emission characteristics of these vehicles under real driving conditions were analyzed and proved that on-road emissions of heavy-duty vehicles(HDVs) were underestimated in the past.There were large differences among LNG and diesel vehicles, which also existed between China V vehicles and China IV vehicles.Emission factors showed the highest level under real driving conditions, which probably be caused by frequent acceleration, deceleration, and start-stop.NOx emission factors ranged from 2.855 to 20.939 g/km based on distance-traveled and 6.719–90.557 g/kg based on fuel consumption during whole tests, which were much higher than previous researches on chassis dynamometer.It was inferred from tests that the fuel consumption rate of the test vehicles had a strong correlation with NOx emission, and the exhaust temperature also affected the efficiency of Selected Catalytic Reduction(SCR) aftertreatment system, thus changing the NOx emission greatly.THC emission factors of LNG vehicles were 2.012–10.636 g/km, which were much higher than that of diesel vehicles(0.029–0.185 g/km).Unburned CH_4 may be an important reason for this phenomenon.Further on-road emission tests, especially CH_4 emission test should be carried out in subsequent research.In addition, the Particulate Number(PN) emission factors of diesel vehicles were at a very high level during whole tests, and Diesel Particulate Filter(DPF)should be installed to reduce PN emission.     

Influence of environmental factors on arsenic accumulation and biotransformation using the aquatic plant species Hydrilla verticillata

Hydrilla verticillata(waterthyme) has been successfully used for phytoremediation in arsenic(As) contaminated water.To evaluate the effects of environmental factors on phytoremediation,this study conducted a series of orthogonal design experiments to determine optimal conditions,including phosphorus(P),nitrogen(N),and arsenate(As(Ⅴ))concentrations and initial pH levels,for As accumulation and biotransformation using this aquatic plant species,while also analyzing As species transformation in culture media after 96-hr exposure.Analysis of variance and the signal-to-noise ratio were used to identify both the effects of these environmental factors and their optimal conditions for this purpose.Results indicated that both N and P significantly impacted accumulation,and N was essential in As species transformation.High N and intermediate P levels were critical to As accumulation and biotransformation by H.verticillata,while high N and low P levels were beneficial to As species transformation in culture media.The highest total arsenic accumulation was(197.2±17.4) μg/g dry weight when As(V) was at level 3(375μg/L),N at level 2(4 mg/L),P at level 1(0.02 mg/L),and pH at level 2(7).Although H.verticillata is highly efficient in removing As(Ⅴ) from aquatic environments,its use could be potentially harmful to both humans and the natural environment due to its release of highly toxic arsenite.For cost-effective and ecofriendly phytoremediation of As-contaminated water,both N and P are helpful in regulating As accumulation and transformation in plants.     

Density functional theory (DFT) studies of vanadium-titanium based selective catalytic reduction (SCR) catalysts

Based on density functional theory (DFT) and basic structure models, the chemical reactions on the surface of vanadium-titanium based selective catalytic reduction (SCR) denitrification catalysts were summarized. Reasonable structural models (non-periodic and periodic structural models) are the basis of density functional calculations. A periodic structure model was more appropriate to represent the catalyst surface, and its theoretical calculation results were more comparable with the experimental results than a non-periodic model. It is generally believed that the SCR mechanism where NH₃ and NO react to produce N₂ and H₂O follows an Eley-Rideal type mechanism. NH₂NO was found to be an important intermediate in the SCR reaction, with multiple production routes. Simultaneously, the effects of H₂O, SO₂ and metal on SCR catalysts were also summarized.