Pollution of intensively managed greenhouse soils by nutrients and heavy metals in the Yellow River Irrigation Region,Northwest China

The present study aimed to assess the potential ecological risk of heavy metals and nutrient accumulation in polytunnel greenhouse soils in the Yellow River irrigation region (YRIR), Northwest China, and to identify the potential sources of these heavy metals using principal component analysis. Contents of available nitrogen (AN), phosphorus (AP), and potassium (AK) in the surface polytunnel greenhouse soils (0–20 cm) varied from 13.42 to 486.78, from 39.10 to 566.97, and from 21.64 to 1,156.40 mg kg^?1, respectively, as well as AP, soil organic matter (SOM) and AK contents tended to increase significantly at the 0–20- and 20–40-cm soil layers. Heavy metal accumulations occurred in the polytunnel greenhouse soils as compared to arable soils, especially at a depth of 20 cm where Cd, Zn and Cu contents were significantly higher than arable soil. Cd and As were found to be the two main polluting elements in the greenhouse soils because their contents exceeded the thresholds established for greenhouse vegetable production HJ333-2006 in China and the background of Gansu province. It has been shown that Cd, Cu, Pb and Zn at the 0–20-cm soil layer were derived mainly from agricultural production activities, whereas contents of Cr and Ni at the same soil layer were determined by ‘natural’ factors and As originated from natural sources, deposition and irrigation water.     

Modelling the connection between energy consumption and carbon emissions in North Africa: Evidence from panel models robust to cross-sectional dependence and slope heterogeneity

Environment, Development and Sustainability - This paper explored the link between energy consumption and carbon emissions in North Africa through an Environmental Kuznets Curve (EKC) framework....     

戊唑醇在环境中的降解迁移和生物富集性研究

戊唑醇属于内吸性三唑类杀菌农药,在国内广泛用于田间病虫防治,故其在环境中的归趋备受关注。采用室内模拟试验方法,研究了戊唑醇在水-沉积物中的降解特性、土壤中的吸附性和在斑马鱼中的生物富集性。结果表明:好氧条件下,戊唑醇在河流与湖泊水-沉积物系统中农药总量的降解半衰期分别为533.2、433.2 d;厌氧条件下,河流与湖泊水-沉积物系统中降解半衰期分别为364.8、1 732.9 d;沉积物系统降解半衰期较长,降解速率主要受水中戊唑醇的降解速率影响。戊唑醇在江西红壤、太湖水稻土、常熟乌杉土、东北黑土中的吸附性符合Freundlich方程,Kd值分别为7.4、11.8、11.2和15;吸附性大小次序为东北黑土太湖水稻土常熟乌杉土江西红壤;以有机碳含量表示的土壤吸附常数KOC在698.9~1 635.5之间;影响戊唑醇土壤吸附性的主要因素为土壤有机质含量和p H。戊唑醇在斑马鱼中的生物富集系数BCF8 d为21.52~25.30,具有中等富集性。戊唑醇在水体环境中具有较强稳定性,不易被土壤吸附,且具有一定的生物富集性,可能会对水体和水体生物造成一定的污染。     

Synthesis of iron composites on nano-pore substrates: Identification and its application to removal of cyanide

Two types of nano-pore substrates, waste-reclaimed (WR) and soil mineral (SM) with the relatively low density, were modified by the reaction with irons (i.e. Fe(II):Fe(III) = 1:2) and the applicability of the modified substrates (i.e. Fe-WR and Fe-SM) on cyanide removal was investigated. Modification (i.e. Fe immobilization on substrate) decreased the BET surface area and PZC of the original substrates while it increased the pore diameter and the cation exchange capacity (CEC) of them. XRD analysis identified that maghemite (γ-Fe₂O₃) and iron silicate composite ((Mg, Fe)SiO₃) existed on Fe-WR, while clinoferrosilite (FeSiO₃) was identified on Fe-SM. Cyanide adsorption showed that WR adsorbed cyanide more favorably than SM. The adsorption ability of both original substrates was enhanced by the modification, which increased the negative charges of the surfaces. Without the pH adjustment, cyanide was removed as much as 97% by the only application of Fe-WR, but the undesirable transfer to hydrogen cyanide was possible because the pH was dropped to around 7.5. With a constant pH of 12, only 54% of cyanide was adsorbed on Fe-WR. On the other hand, the pH was kept as 12 without adjustment in Fe-WR/H₂O₂ system and cyanide was effectively removed by not only adsorption but also the catalytic oxidation. The observed first-order rate constant (k_obs) for cyanide removal were 0.49 (±0.081) h⁻¹. Moreover, the more cyanate production with the modified substrates indicated the iron composites, especially maghemite, on substrates had the catalytic property to increase the reactivity of H₂O₂.     

活性炭和沸石对氨氮的吸附特性及生物再生

采用活性炭和沸石作为吸附材料,分别考察了这两种吸附材料对水体中氨氮的吸附特性及其生物再生性能。实验结果表明,活性炭和沸石对水体中氨氮的等温吸附符合Freundlich等温式,其拟合度分别为0.9783和0.9303;静态吸附结果表明活性炭和沸石均具有较好的氨氮吸附性能,24 h内沸石对氨氮的吸附能力为1.27 mg/g,高于活性炭的0.53 mg/g;动态吸附中沸石达到吸附饱和的时间为96 h,较活性炭达到吸附饱和的时间长,沸石显示出作为氨氮吸附剂的优越性;活性炭和沸石经过96 h的生物再生后吸附性能获得一定程度的再生,出水中氨氮浓度比未进行生物再生前分别降低17.31 mg/L和8.32 mg/L,且都在表面形成了稳定的生物膜。     

混凝沉淀法深度处理酒精废水

采用混凝沉淀法对酒精废水进行深度处理实验及放大应用研究。结果表明,混凝剂种类、投加量、pH值及沉降时间对处理效果都起着重要作用。通过正交实验确定最优化组合,即聚合硫酸铝投加量为60mg／L,pH为8．0左右,沉降时间为90min条件下,废水COD去除率达41．91％;浊度去除率达46．15％;NH3-N去除率达49．61％。混凝沉淀法处理酒精废水可有效减轻后续膜处理工艺负荷,有助于提高回用水质。     

石油污染土壤中孤东原油及其馏分的微生物降解性能

分别以孤东油区石油污染土壤中的原油、柴油馏分(180～360℃)、蜡油馏分(360 ～ 500℃)为研究对象,采用BC-Ⅰ和BC-E 2种菌剂,对其进行微生物降解.研究表明,BC-Ⅰ和BC-E菌剂对石油污染土壤中石油烃的降解效果明显,BC-E菌剂对孤东油区石油污染土壤中石油烃的降解率达35.7％.2种菌剂对石油烃中轻馏分的降解效率均远远高于其对重馏分的降解效率.柴油馏分降解产物中鉴定出O1、O2、N1等多种分子类型,其中O2相对丰度远高于O1、N1类型,研究表明,该类化合物是脂肪酸,油样中脂肪酸存在明显的C16、C18优势,降解后低碳数脂肪酸相对丰度略有增加.蜡油(VGO)降解后以m/z=293(C19双环环烷酸)为中心正态分布,烷基咔唑中C5-咔唑丰度最高,苯并咔唑相对丰度很低.O2类化合物丰度很低,表明脂肪酸含量很低,DBE为4或5的O2类化合物明显占优势,对应3～4环环烷酸丰度较高.     

高藻水中新生态三价铁混凝行为及其对絮体生长的影响

通过阐释新生态三价铁活性高的机制从而提出混凝剂的连续投加方式对混凝除藻效果的促进作用。与高锰酸钾-铁混凝过程相比,高锰酸钾-亚铁混凝过程初期絮体粒径较小;但经过一段时间后,后者絮体粒径将明显大于前者。Mn(VII)投量为1.7μmol/L时,混凝进行到720 s之前高锰酸钾-亚铁混凝过程中絮体粒径均低于200μm,反应进行到990s时絮体粒径稳步增大到239μm。形成对比的是,高锰酸钾-铁混凝过程进行到720 s和990 s时絮体粒径分别为198μm和204μm。在混凝过程中,亚铁逐步转化生成新生态三价铁,相当于向系统中持续投加混凝剂。在混凝剂总量相同(197.4μmol/L)的情况下,分次连续投加Fe(III)比一次性投加Fe(III)所生成的絮体粒径要大32%。     

Cu-SBA-15催化湿式过氧化氢氧化水溶液中罗丹明B

采用水热晶化法合成了不同含铜量的Cu-SBA-15介孔分子筛,并且用XRD、N2吸附、TEM以及UV-vis对所合成的样品进行表征。以Cu-SBA-15为催化剂,H2O2为氧化剂,催化湿式过氧化水溶液中的罗丹明B,主要考察H2O2浓度、催化剂用量、处理温度、初始pH等因素对罗丹明B氧化效果的影响。结果表明,在同样的处理条件下罗丹明的脱色率明显高于TOC去除率,处理温度、初始pH对罗丹明B的脱色与氧化有重要影响。在罗丹明B初始浓度100 mg/L,H2O2初始浓度1.8 g/L,催化剂量0.3 g/L,温度60℃,pH为7.0,处理时间100 min时,罗丹明B的脱色率为98.6%,TOC去除率为62.8%。     

活性污泥法处理高钙废水中污泥特性的变化

通过单级SBR法处理模拟高钙废水,研究了活性污泥法处理高钙废水的过程中钙离子对COD,MLVSS,MLSS,SVI,污泥增长速率,污泥形态结构及生物相的影响,揭示活性污泥法处理高钙废水的过程中污泥量巨大的原因。采用逐步增加钙离子浓度的方法,检测到在污泥培养期([Ca2+]=0 mg/L),COD去除率为98.1%,MLVSS和MLSS稳定在4 900~5 500mg/L,污泥增长速率为67 mg/(L·d),SVI为55~60 mL/g;在驯化处理期([Ca2+]=120~2 400 mg/L),COD去除率降至87.37%,MLVSS降至2 500 mg/L,MLSS增加至19 300 mg/L,污泥增长速率为212.31 mg/(L·d),SVI降至25 mL/g;在冲击期([Ca2+]=4 000 mg/L),COD去除率降至69.23%,MLVSS降至1 600 mg/L,MLSS迅速增加至24 200 mg/L,污泥增长速率为816.67 mg/(L·d),SVI降至14 mL/g。经显微镜观察发现,污泥絮体由松散变得密实,生物相由钟虫等指示性微生物变为不适应环境的胞囊结构。结果表明,随Ca2+浓度的增加,COD去除率下降,MLSS迅速增加,MLVSS和SVI急剧缩小,说明活性污泥中的活性微生物逐渐减少,而无机物组分逐渐增多;钙离子的加入促使系统碳酸平衡向右移动,使离子状态的钙大部分转化为难降解的碳酸盐,并附着于污泥絮体上,污泥绒粒被压缩,使污泥颗粒密实度及MLSS迅速增加,导致污泥排放量巨大。