Characterization of cadmium uptake,translocation, and distribution in young seedlings of two hot pepper cultivars that differ in fruit cadmium concentration

The reasons why some cultivars of hot pepper (Capsicum annuum L.) accumulate low levels of Cd are poorly understood. We aimed to compare the characteristics of Cd uptake and translocation in low-Cd and high-Cd hot pepper cultivars by determining the subcellular locations and chemical forms of Cd, and its distribution among different plant organs. We conducted a hydroponic experiment to investigate the subcellular distribution and chemical forms of Cd in roots, stems, and leaves of a low-Cd (Yeshengchaotianjiao, YCT) and a high-Cd cultivar (Jinfuzaohuangjiao, JFZ). The results showed that the concentrations of Cd in almost all subcellular fractions of roots, and in all chemical forms in roots, were higher in YCT than in JFZ. Compared with YCT, JFZ had higher Cd concentrations in almost all subcellular fractions of stems and leaves, and higher Cd concentrations in almost all chemical forms in stems and leaves. Additionally, YCT had significantly higher total Cd accumulation but a lower Cd translocation rate compared with JFZ. In general, the results presented in this study revealed that root-to-shoot Cd translocation via the xylem is the key physiological processes determining the Cd accumulation level in stems and leaves of hot pepper plants. Immobilization of Cd by the cell walls of different organs is important in Cd detoxification and limiting the symplastic movement of Cd.     

西安夏季PM2.5中碳组分与水溶性无机离子特征分析

2012年8月6日—22日利用大气细颗粒物水溶性组分在线监测分析系统和大气气溶胶OC/EC在线分析仪在线分析了西安PM2.5中的水溶性无机离子和OC、EC,并结合气溶胶前体物SO2、NO2和部分气象参数的监测数据进行了分析。结果表明,PM2.5中OC、EC和主要水溶性组分SO2-4、NH+4和NO-3的比重分别为:14.34%、5.35%、26.32%、12.90%和11.28%;以有机物(OM)为主要成分的总碳气溶胶(TCA)在PM2.5中的质量分数为28.30%,其中光化学反应导致OM中二次组分(SOC)高达45.30%;对主要水溶性组分之间的相关性分析发现,NO-3、SO2-4、NH+43种主要组分之间的结合形态为(NH4)2SO4和NH4NO3,对Mg2+和Ca2+的相关分析反映其有多种共同源;此外,硫氧化率(SOR)和氮氧化率(NOR)均较高,表明大气中存在较强的光化学反应。PM2.5的各组分因子分析得到4个主要来源(机动车尾气和燃煤、土壤建筑尘和生物质燃烧、二次硝酸盐气溶胶、二次硫酸盐气溶胶)。     

pH值对"Fe0-厌氧微生物"体系去除2,4,6-三氯酚过程的影响

考察了pH值对"Fe0-厌氧微生物"体系降解2,4,6,-三氯酚(2,4,6-TCP)效果的影响,结果表明:pH值是影响"Fe0-厌氧微生物"体系降解2,4,6-TCP效果的重要参数,初始pH值直接影响微生物活性和铁腐蚀,进而影响过程pH值变化,反过来又影响铁腐蚀和微生物活性,pH 7.0～9.0的中性偏碱范围较适于厌氧微生物生长。Fe0与微生物对目标污染物的降解具有协同促进作用,其协同促进机制表现在3方面:Fe0与微生物对体系过程pH值具有互补调节作用,可将体系的pH值调节值适于微生物生长的中性范围;Fe0腐蚀产生的Fe2+和H2可为微生物代谢提供电子对和营养物质,从而促进生物还原脱氯的进行;Fe0的腐蚀过程直接对氯代有机物还原脱氯,而微生物又可促进Fe0腐蚀。     

Characteristics of an aerobic denitrifier that utilizes ammonium and nitrate simultaneously under the oligotrophic niche

Introduction

An aerobic denitrifier was isolated from the Hua-Jia-Chi pond in China and identified as Pseudomonas mendocina 3-7 (Genbank No. HQ285879). This isolated strain could express periplasmic nitrate reductase which is essential for aerobic denitrification occurred when the dissolved oxygen (DO) level maintains at 3?C10?mg?L^?1.

Methods

To determine whether the ability of isolated strain is exhibited in the bioremediation of polluted drinking source water, the heterotrophic nitrification and aerobic denitrification characteristics of P. mendocina 3-7 under different cultural conditions such as oxygen level, nitrate and organic concentrations were studied from the nitrogenous balance in the paper.

Results and conclusions

By measuring the nitrogen balance in all experiments under different culture conditions, the removal of total organic carbon and ammonium was positively correlated with total nitrogen removal, especially under high substrate level. With substrate concentration decreasing, ammonium and nitrate removal occurred separately, and ammonium was completely utilized first under low substrate concentration. Compared to that under high substrate level, the specific growth rate of P. mendocina 3-7 was not low under the low substrate level and the pollutant removal efficiencies remained high, which implies the stronger nitrogen removal and acclimatization capacities of the strain in oligotrophic niches.     

层次分析法与向量模法在水环境承载力评价中的应用——以胶州市为例

从社会经济、资源利用、与环境管理等角度分析了胶州市水环境承载力的主要影响因素,综合构建了胶州市水环境承载力评价指标体系。采用层次分析法和向量模法对胶州市2007~2011年水环境承载力进行了评价。结果表明,胶州市水环境承载力评价值范围为0.061~0.080,胶州市水环境承载力水平较低,总体上呈先下降后上升的趋势,其中,水资源短缺为制约胶州市水环境承载力的主要因素。     

棉铃虫暴发的特点,成因及治理对策

本文就１９９２年我国棉铃虫暴发成灾的特点与成因进行了详细的分析，并讨论了治理这一灾害性农业害虫的策略与方法。     

雨水花园土壤重金属的累积效应与污染风险研究

土壤中重金属累积可污染土壤和地下水,危害人类身体健康.雨水花园作为海绵城市建设过程中雨水径流集中入渗的重要措施之一,长期雨水径流集中入渗导致雨水花园土壤发生重金属累积和污染风险.本文以陕西省西安市某高校内雨水花园为研究对象,该雨水花园建成于2011年,运行至今（2020年）,汇流面积为604.7 m²,汇流比为20：1,主要收集屋面雨水.雨水花园土壤重金属监测时间为2017年4月—2019年4月,采用富集系数法、单因子污染指数法、内梅罗综合污染指数法对雨水花园重金属累积和污染风险进行评价.结果表明：雨水花园各土层均有3种元素（Cu、Zn、Cd）累积,Cu在土壤中小幅累积,Zn在土壤表层轻微富集,其它各层基本未富集;Cd在不同土层中富集程度不同,且易受人为活动影响.经单因子污染指数法、内梅罗综合污染指数法分析评价,Cu、Zn元素虽有累积,但未达到污染标准;各层土壤均受到Cd的污染,污染等级均为轻污染.     

固相萃取技术预富集环境水样中邻苯二甲酸酯

使用Ｃ₁₈固相萃取柱，系统地研究了环境水样中邻苯二甲酸酯类化合物的固相萃取预富集方法，考虑影响回收率的４个主要因素，即水样流速、洗脱溶剂、洗脱溶剂用量及洗脱速率，利用正交试验进行萃取条件的优化．最后确定最佳萃取条件为：水样流速４ｍ ｌ·ｍ ｉｎ^-1，洗脱溶剂为乙酸乙酯、洗脱溶剂用量２ｍ ｌ，洗脱速率２ｍｌ·ｍ ｉｎ^-1．并探讨了其它影响萃取效果的因素，除邻苯二甲酸二辛酯（ＤＥＨＰ）外，邻苯二甲酸二甲酯（ＤＭＰ）、邻苯二甲酸二乙酯（ＤＥＰ）、邻苯二甲酸二丁酯（ＤＢＰ）的固相萃取回收率在９６．５％ ～１２０％ 范围内，相应化合物的液－液萃取回收率为９２．９％ ～１２０％ ． 表明固相萃取，在环境水样中的邻苯二甲酸酯类化合物分离富集方面可以取代液－液萃取． 同时，进行了固相萃取柱在不同条件下的贮存实验．     

金城造纸厂综合污水处理工程调试运行

总结了采用好氧工艺处理造纸工业废水中各个不同调试阶段及对应的工艺运行参数。该废水难生化降解,其ρ(BOD5)/ρ(COD)值在23.3%左右,而且废水中N、P等营养元素含量不足。通过投加尿素和磷酸氢二氨,使均质池TN、TP含量满足微生物生长;同时降低进水ρ(COD)值至1500mg/L,提高曝气池溶解氧量至3.0mg/L,污泥浓度至4500mg/L,将COD污泥负荷从最初0.45～0.55kg/(kg·d)逐渐下降到0.30～0.35kg/(kg·d),经过2个月的调试运行,出水各参数达到设计排放标准:COD为450mg/L、BOD5为25mg/L、pH为6.8。     

太湖沉积物中重金属污染状况及分布特征探讨

依据沉积学原理和水体沉积物重金属的环境地球化学特性，用地积累指数法和改进的多变量Chernoff脸谱图，对太湖沉积物中重金属的污染状况及不同重金属的地积累程度进行了综合性的评价。结果表明：（1）太湖沉积物中重金属的污染可划分为3个区域：湖心相对清洁区、湖岸轻度污染区和内湖综合污染区。（2）太湖沉积物中重金属存在轻度污染。其中铜污染极别高于其它金属，且集中的太湖北部地区。铬污染属于轻度污染，具有分布空间广且均衡的特点。