Heavy metals in rice and garden vegetables and their potential health risks to inhabitants in the vicinity of an industrial zone in Jiangsu, China

Contamination of soil and agricultural products by heavy metals resulting from rapid industrial development has caused major concern. In this study, we investigated heavy metal (Cu, Zn, Pb, Cr, Hg and Cd) concentrations in rice and garden vegetables, as well as in cultivated soils, in a rural-industrial developed region in southern Jiangsu, China, and estimated the potential health risks of metals to the inhabitants via consumption of locally produced rice and garden vegetables. A questionnaire-based survey on dietary consumption rates of foodstuffs showed that rice and vegetables accounted for 64% of total foodstuffs consumed, and over 60% of rice and vegetables were grown in the local region. Average concentrations of Cr, Cu, Zn, Cd, Hg and Pb were 0.75, 2.64, 12.00, 0.014, 0.006 and 0.054 mg/kg dw (dry weight) in rice and were 0.67, 1.18, 4.34, 0.011, 0.002 and 0.058 mg/kg fw (fresh weight) in garden vegetables, respectively. These values were all below the maximum allowable concentration in food in China except for Cr in vegetables. Leafy vegetables had higher metal concentrations than solanaceae vegetables. Average daily intake of Cr, Cu, Zn, Cd, Hg and Pb through the consumption of rice and garden vegetables were 5.66, 16.90, 74.21, 0.10, 0.04 and 0.43 μg/(kg·day), respectively. Although Hazard Quotient values of individual metals were all lower than 1, when all six metal intakes via self-planted rice and garden vegetables were combined, the Hazard Index value was close to 1. Potential health risks from exposure to heavy metals in self-planted rice and garden vegetables need more attention.     

两种分子量分级下DOM的组分特征及其生物毒性

分别采用超滤离心管和超滤杯两种方式制备不同分子量的溶解性有机物（DOM）,探究不同的分子量分级方式对获得的DOM组成成分特征及其生物毒性效应的影响,同时判明各组分联合作用方式.DOM分别来源于城市污水厂出水（EfOM）及商品天然腐植酸（SWR-NOM）.结果表明,两种分级方式获得的不同分子量DOM含有相同的荧光峰,腐殖酸类物质是EfOM与SWR-NOM含有的主要荧光类有机质（FDOM）,占FDOM的56%~91%.同种DOM不同分子量组分中FDOM组成相对含量一致.采用超滤离心管分级得到的DOM在不同分子量区间内SUVA₂₅₄和E2/E3的差异较大,而采用超滤杯分级时差异变化较小.对于发光细菌急性毒性,在同一分子量区间内,采用超滤杯分级获得的DOM组分检测到的发光细菌毒性值大于采用超滤离心管分级检测到的结果,但采用超滤杯分级时<1kDa组分的急性毒性效应值低于检测限.利用浓度加和模型（CA）对DOM中各组分的联合作用方式进行判断,发现DOM混合物的联合毒性符合CA模型,预测联合毒性效应占检测到的实际水样毒性的67%~104%.     

Characteristics of molecular weight distribution of dissolved organic matter in bromide-containing water and disinfection by-product formation properties during treatment processes

The characteristics of dissolved organic matter (DOM) and bromide ion concentration have a significant influence on the formation of disinfection by-products (DBPs). In order to identify the main DBP precursors, DOM was divided into five fractions based on molecular weight (MW), trihalomethane formation potential and haloacetic acid formation potential were determined for fractions, and the change in contents of different fractions and total DBPs during treatment processes (pre-chlorination, coagulation, sand filtration, disinfection) were studied. Moreover, the relationship between bromide concentration and DBP generation characteristics in processes was also analyzed. The results showed that the main DBP precursors were the fraction with MW < 1 kDa and fraction with MW 3−10 kDa, and the DBP''s generation ability of lower molecular weight DOM (< 10 kDa) was higher than that of higher molecular weight DOM. During different processes, pre-chlorination and disinfection had limited effect on removing organics but could alter the MW distribution, and coagulation and filtration could effectively remove organics with higher MW. For DBPs, trihalomethanes (THMs) were mainly generated in pre-chlorination and disinfection, while haloacetic acids (HAAs) were mostly generated during pre-chlorination; coagulation and sand filtration had little effect on THMs but resulted in a slight removal of HAAs. In addition, the results of ANOVA tests suggested that molecular sizes and treatment processes have significant influence on DBP formation. With increasing bromide concentration, the brominated DBPs significantly increased, but the bromine incorporation factor in the processes was basically consistent at each concentration.     

径流溶解性有机物对生物滞留介质去除Cu2+和Pb2+的影响

分别以惰性介质（土、砂）和强化介质（给水厂污泥、铁锰复合氧化物）为研究对象,考察道路径流溶解性有机物（DOM）存在对生物滞留介质吸附去除Cu²⁺和Pb²⁺过程的影响,并揭示其主要响应组分及作用机制.结果表明,径流DOM、DOM各分子量组分和各化学组分均可抑制惰性生物滞留介质对Cu²⁺和Pb²⁺的吸附去除,促进强化生物滞留介质对两者的吸附去除;其中,径流DOM中<1kDa分子量组分和亲水性组分对惰性介质吸附去除Cu²⁺和Pb²⁺的抑制作用最明显、对强化介质吸附去除Cu²⁺和Pb²⁺的促进作用也最明显,是影响生物滞留介质对Cu²⁺和Pb²⁺吸附过程的关键DOM组分.<1kDa分子量组分存在使砂介质对Cu²⁺和Pb²⁺的吸附量减少了62.96%和83.70%,使铁锰复合氧化物介质对Cu²⁺和Pb²⁺吸附量增加了81.16%和4.67%;亲水性组分存在使土介质对Cu²⁺和Pb²⁺的吸附量最高减少了41.43%和69.12%,使给水厂污泥介质对Cu²⁺和Pb²⁺的吸附量最高增加了32.35%和39.06%.     

长江沿线城市水源氯(胺)化消毒副产物生成潜能研究

以长江上游重庆、中游武汉、下游上海等大城市的长江饮用水源为研究对象,在对溶解性有机物分子量和亲疏水性分离的基础上,分别采用氯和氯胺两种方式消毒,对比分析了相同时期沿江这些城市原水中氯(胺)化常规和新兴含氮消毒副产物生成潜能的分子组成规律.研究表明,重庆、武汉、上海三地的溶解性有机物均以小分子前体物为主,主要分布在<1kDa的区间内,且以强疏水性成分和亲水性成分为主,原水经氯(胺)化可产生三卤甲烷、卤乙酸、卤乙腈、三氯硝基甲烷等类型的消毒副产物;三地的氯(胺)化主要的含碳消毒副产物(C-DBPs)和含氮消毒副产物(N-DBPs)生成潜能均在<1kDa的区间内最大,从上游到下游,在<1kDa的区间内的生成潜能占各自总潜能比例逐渐增加.三地的氯(胺)化的C-DBPs和N-DBPs生成潜能均以强疏水性组分或亲水性组分为主,且氯胺化可导致亲水性组分C-DBPs和N-DBPs生成潜能所占总量比例增加.     

Aging effect on the mobility and bioavailability of copper in soil

Aging effect on the mobility and bioavailability of copper (Cu) was investigated using a spiked soil with different incubation periods from 3 to 56 d. Wheat was planted and earthworm was cultured separately in the incubated soils. The mobility of Cu in soil was evaluated by a chemical fractionation scheme and the toxicity and bioavailability were assessed by measuring the biomass and Cu concentration in tissues. Results showed that aging had a significant effect on Cu fraction distribution, of which Cu tended to incorporate from the exchangeable into more stable fractions such as the reducible and oxidisable fractions. However, aging had little effect on Cu bioavailability to wheat and earthworms. Comparing the soil being incubated for 3 d and 56 d, Cu concentration in wheat roots decreased from 14.5 to 12.8 mg/kg, and no significant changes in Cu concentration were observed in both wheat shoots and earthworms. The Cu concentration was around 2.0 and 50 mg/kg for wheat shoots and earthworms, respectively, irrespective of soil incubation time. The CaCl2-extractable Cu had a linear relationship with Cu concentration in wheat roots (R2 = 0.65, P < 0.05), but no linear relationship can be found for wheat shoots and earthworms. Biological control may be more crucial for Cu accumulation in organism than the changes in soil Cu fraction caused by aging.     

河流不同分子量溶解性有机质对全氟化合物赋存形态的影响

目前有关水体全氟化合物(PFASs)赋存特征的研究主要集中于总溶解态,对溶解性有机质(DOM)结合态PFASs的研究较为匮乏,尤其忽视了不同分子量DOM对PFASs赋存形态的影响. 为阐明河流上覆水体不同分子量DOM对PFASs赋存形态的影响,本文以长江干支流为例,分析了河流上覆水体11种典型PFASs (C4~C12)的浓度及组成,研究了不同分子量DOM结合态PFASs的赋存特征. 结果表明:①长江上覆水体中PFASs的平均浓度为52.6 ng/L,其中全氟戊酸(PFPeA)和全氟己酸(PFHxA)是最主要的单体污染物;由于受点源污染的影响,武汉段PFASs总溶解浓度及其单体浓度均显著高于其他采样点. ②长江上覆水体中DOM的浓度范围为0.08~3.84 mg/L (以C计),将水体DOM按分子量分离为<1 kDa、1~3 kDa、3~5 kDa、5~10 kDa和>10 kDa五种组分,各采样点中<1 kDa的溶解性有机碳(DOC)浓度(1.56~3.84 mg/L)显著高于其他分子量的DOC浓度. ③对于所检出的PFASs,<1 kDa DOM结合态PFASs (含自由溶解态)的浓度亦显著高于其他分子量DOM结合态PFASs的浓度,且其占水体总溶解态PFASs的比例均在85%以上,说明水体DOM结合态PFASs具有较高的生物有效性. 研究显示,水体不同分子量DOM结合态PFASs的赋存特征存在差异,因此对水体PFASs进行生态风险评价时需综合考虑不同分子量DOM结合态的含量及其生物有效性.      

贵州百花湖水中溶解有机质的分子量分布随深度的变化规律

利用高效体积排阻色谱法测量了百花湖水中溶解有机质的分子量及其分布。结果表明百花湖水中溶解有机质（DOM）主要以分子量小于3500道尔顿（Da）的组分为主,其中重均（Mw）和数均（Mn）分子量分别界于2300～2500 Da和1900～2150 Da之间,说明其主要来源于降水对土壤有机物的淋滤和径流作用。根据色谱分析的结果,可以把溶解有机质的分子量分布分为四个组分：大分子量组分（MW〉3500 Da）;中等偏大分子量组分（3500～2000 Da）;中等分子量组分（2000～1000 Da）和小分子量组分（MW〈1000 Da）。由于生物活动和光降解作用以及有机物的分解作用,导致各分子量组分随深度的变化规律不同,其中分子量在3500～2000 Da之间的有机物的含量随深度的增大而增大,其余组分的含量随深度的增大而减少。计算所得的溶解有机质的Mw和Mn在表层较小,在中部随深度基本保持不变,到底部又变大。这种变化趋势与分子量组分的变化结果一致。     

贵阳南明河水中溶解有机质分子量的初步研究

采用高效液相色谱系统对南明河中的有机物含量及分子量的分布特征进行了研究。南明河有机物的分子量呈多峰状态分布,分子量分布从大于3500 Da到小于1000 Da的有机物都存在。分子量在1000 Da～3500 Da之间的有机物含量占比71％～88％,分子量小于1000 Da和大于3500 Da的有机物含量很小。从整个南明河来看,上游和下游的有机物的分子量相对比较大,而中游的分子量相对比较小。     

黄河干流宁蒙段溶解性有机物组分特征及其与金属离子的相关性

溶解性有机物(dissolved organic matter,DOM)是天然水体的重要组成部分,由于化学极性及所含的官能团不同,其在水体中的化学行为也不同.本研究以黄河干流宁蒙段为研究对象,于2015年4月采集了下河沿至头道拐沿程7个断面的水样,采用XAD系列树脂将DOM分为疏水性酸(hydrophobic acid,HOA)、疏水性碱(hydrophobic base,HOB)、弱疏水性酸(weak hydrophobic acid,WHOA)和亲水性物质(hydrophilic matter,HYI)这4个组分,探讨了DOM组分含量、荧光峰值及其与Pb、Zn、Cu、Cr、As这5种金属离子之间的相关性.结果表明,黄河宁蒙段DOM总量由下河沿至头道拐沿程逐渐增加.各断面DOM腐殖化程度较低,以亲水性的蛋白质类小分子物质(HYI)为主,疏水性酸(HOA)次之,这与黄河沿岸排污导致内源作用增强有关.三维荧光光谱中类腐殖质和类蛋白质荧光峰型显著,且类腐殖质峰沿程逐渐增强,进一步证实了内源污水输入的影响.SPSS相关性分析结果表明,DOM与5种金属离子呈现出不同程度的相关性,其中与Cu离子显著相关;4种组分中HYI与Cu离子的相关性最强,说明二者在迁移转化过程中存在显著相互作用.进一步研究发现,芳香蛋白类物质荧光峰强度随Cu离子浓度的升高而降低,这可能是Cu与亲水性组分中的芳香类蛋白质发生络合产生荧光淬灭效应,从而导致荧光强度降低.