豆渣膳食纤维吸附重金属的研究

通过体外试验模拟人体胃和肠道的pH环境,分别评价经过乳酸菌发酵、动态高压微射流处理过的豆渣膳食纤维吸附3种重金属离子(Hg2+、Cd2+和pb2+)的能力.结果表明,豆渣膳食纤维对3种重金属离子都有一定的吸附作用,吸附能力pb2+＞Hg2+＞Cd2+,且在20 min内可达到吸附平衡,肠道环境更有利于吸附.乳酸茵发酵和动态高压微射流处理均增强了豆渣膳食纤维的吸附作用.     

Binding of four heavy metals to hemicelluloses from rice bran

This paper demonstrates that rice bran hemicellulose A (RBHA), hemicellulose B (RBHB) and hemicellulose C (RBHC) have the potential for binding heavy metal ions. The quantity of metal ions bound varies from one rice bran fibre to another. As it can be inferred from the results of the study, RBHB was characterised by the highest capacity for metal ion (Pb, Cu and Cd) binding, followed by RBHC and RBHA. Binding of heavy metals to insoluble dietary fibre (RBDF) and cellulose from rice bran were found to be poor. Lignin from rice bran was the least active fraction for binding heavy metal ions.     

Research Watch: Binding heavy metals in soil

Remediation.     

Adaptation of soil biological nitrification to heavy metals

The adaptive response of soil biological nitrification to Zn and Pb was assessed using an in situ method we have developed. The method is based on reinoculating a sterilized metal contaminated soil with the same soil that is either uncontaminated or has been incubated with metal. This approach excludes the potentially confounding effects of metal aging reactions in soils. We found added Zn concentrations which gave rise to a decrease in nitrification to 50% that of the uncontaminated soil (i.e. EC50) of 210 mg/kg for communities not previously exposed to Zn and 850 mg/kg for communities exposed to Zn for 17 months, indicating that significant adaptation of the community to Zn had occurred. Similarly, this protocol was able to demonstrate adaptation of soil biological nitrification to Pb, with EC50 values of 1960 and 3150 mg/kg for the unexposed and exposed treatments, respectively. Exposure of unadapted and adapted microbial communities to a combination of Zn and Cd showed that the presence of Cd did not lead to greater toxicity in either community. Adapted communities were not more sensitive to decreases in soil pH than unadapted communities. Prior exposure to Zn was found to confer significantly greater tolerance of the community to Pb. Prior exposure to Pb similarly conferred significantly greater tolerance of the community to Zn. Implications of the adaptive capacity of soil microbes to the development of critical threshold values for heavy metals in soil based on ecotoxicity assessments are discussed.     

微波辅助法和酶法制备苹果渣膳食纤维特性研究

以苹果渣为原料,分别采用微波辅助法和酶解法制备水溶性膳食纤维(SDF)和不溶性膳食纤维(IDF),对4种膳食纤维超微结构进行了比较,并研究了其持水力、溶胀性、油脂吸附力和胆酸钠吸附性,以期为制备高活性苹果渣膳食纤维提供依据。结果表明:微波辅助法和酶法制备的苹果渣SDF结构松散,呈现絮状和颗粒状,IDF呈片状;SDF具有良好的持水力和溶胀性,与IDF存在显著性差异,微波法和酶法SDF的持水力分别达752.3%和793.2%,溶胀性分别为11.1 m L/g和13.05 m L/g;SDF油脂吸附能力高于IDF,对饱和油脂吸附效果更加明显;苹果渣IDF对胆酸钠吸附能力强于SDF,以微波辅助法提取的IDF对胆酸钠的吸附能力最好,为93.33 mg/g。     

甜橙皮渣膳食纤维中类黄酮化合物含量分祈

实验以甜橙皮渣为原料,采用不同处理方法制备了9种膳食纤维,通过高效液相色谱仪器测定其中的类黄酮化合物含量,发现得到的膳食纤维中仍然含有大量的类黄酮化合物,而且其含量与膳食纤维制备方法和自身的结构有关,为甜橙皮渣的综合利用提供了新思路.     

中国居民水产品中四种常见重金属暴露评估

目的评估中国居民水产品中铅、镉、汞、砷四种重金属的暴露水平和健康风险。方法利用2013—2017年水产品中铅、镉、汞、砷的含量监测数据和相应食物消费量数据,采用简单分布评估方法,计算中国居民水产品中四种重金属的摄入情况,依据相应健康指导值或基准剂量评估其潜在危险。结果各性别-年龄组人群镉、甲基汞的暴露量均低于其相应健康指导值,但除66岁以上女性组镉平均暴露量外,平均暴露量均在相应健康指导值的5%以上,高端暴露量(P95)超过健康指导值的20%。各人群铅、无机砷的暴露限值(MOE)均高于1。2～6岁性别-年龄组除无机砷外,另三种重金属平均暴露量和P95在各性别-年龄组中均最高。水产品中四种重金属贡献率最高的为海蟹和鱼类。结论中国居民通过水产品的铅、镉、汞、砷暴露量总体上低于相应的健康指导值或基准剂量,但达到通过制定限量标准进行管理的水平。鱼类和海蟹是对四种重金属暴露贡献率最高的水产品,高消费人群的重金属暴露需要加以关注,建议进一步开展重金属的累积暴露评估研究,明确水产品中重金属的累积暴露风险。     

2007—2014年绍兴地区蔬菜中重金属污染调查

目的了解绍兴地区蔬菜中铅、镉和总汞的含量水平及污染程度,为制定蔬菜中重金属污染控制措施提供依据。方法 2007—2014年在绍兴地区7个调查点的农贸市场、超市等地点随机抽取7类共984份蔬菜样品,采用国家标准方法检测蔬菜中铅、镉和总汞的含量,按GB 2762—2012《食品中污染物限量》统计超标情况。采用单因子污染指数和内梅罗综合污染指数评价蔬菜中重金属污染程度。结果 984份蔬菜样品铅、镉和总汞的检出率分别为68.4%(673/984)、92.0%(905/984)和37.6%(370/984),超标率分别为2.9%(29/984)、1.2%(12/984)和5.8%(57/984),平均值分别为0.040、0.017和0.004 0 mg/kg;2009—2011年蔬菜中总汞超标率较高,超标率分别为17.3%(19/110)、24.7%(19/77)和10.1%(12/119);鳞茎类蔬菜中铅和镉超标率分别为14.0%(6/43)和11.6%(5/43),均为各类蔬菜中最高。所有种类蔬菜的综合污染指数均小于0.7。结论绍兴地区蔬菜中重金属总体污染水平不高,但部分蔬菜中重金属污染相对较突出,应继续加强监管和控制。     

Sugar beet pulp and apple pomace dietary fibers improve lipid metabolism in rats fed cholesterol

The effect of diets supplemented with sugar beet pulp fiber (SBP, 10%) and apple pomace fiber (AP, 10%) on lipids and lipids peroxides was investigated in 60 male Wistar rats. The rats were divided into six groups of 10 and adapted to cholesterol-free or 0.3% cholesterol diets. The basal diet (BD) contained wheat meal, barley meal, wheat hulls, meat-bone meal, barley sprouts, skimmed milk, fodder yeast, mineral and vitamin mixtures. The Control group (Control) consumed BD only. To the BD were added 3 g/kg cholesterol (Chol), 100 g/kg dry sugar beet pulp fiber (SBP), both 100 g/kg sugar beet pulp fiber and 3 g/kg cholesterol (SBP+Chol), 100 g/kg apple pomace fiber (AP), both 100 g/kg apple pomace fiber and 3 g/kg cholesterol (AP+Chol). The experiment lasted 40 days. Plasma total cholesterol (TC), LDL cholesterol (LDL-C), HDL cholesterol (HDL-C), triglycerides (TG), total phospholipids (TPH), HDL phospholipids (HDL-PH), lipid peroxides (LP) and liver TC concentration were measured. Groups did not differ before the experiment. In the Chol+SBP and the Chol+AP vs. Chol group the sugar beet pulp and apple pomace dietary fiber supplemented diet significantly (P<0.05) hindered the rise of plasma lipids: (a) TC−2.97 vs. 3.69 mmol/l, −20% and 3.01 vs 3.69 mmol/l, −18.4%, respectively; (b) LDL-C −1.36 vs. 2.02 mmol/l, −32.6% and 1.39 vs. 2.02 mmol/l, −31.2%, respectively; (c) TG −0.73 vs. 0.88 mmol/l, and 0.75 vs. 0.88 mmol/l; −17 and −14.8%, respectively, and TC in liver (17.1 vs. 24.3 μmol/g, −29.6% and 17.9 v. 24.3 μmol/g, −26.3%, respectively. Sugar beet and apple pomace fiber-supplemented diets significantly hindered the decrease in HDL-PH (0.79 vs. 0.63 mmol/l, −25.3%, P<0.025 and 0.75 vs. 0.63 mmol/l, −19%, P<0.05, respectively) and decreased the level of TPH (1.34 vs. 1.74 mmol/l, −23%, P<0.005 and 1.37 vs. 1.74 mmol/l, −21.3%, P<0.01, respectively). Both sugar beet pulp fiber and apple pomace fiber, in rats fed the basal diet without cholesterol, did not significantly affect the variables measured. Neither sugar beet pulp fiber or apple pomace fiber-supplemented diets influenced the level of lipid peroxides. These results demonstrate that sugar beet pulp fiber and to a lesser degree apple pomace fiber possess hypolipidemic properties. This is more evident when sugar beet pulp fiber or apple pomace fiber are added to the diet of rats fed cholesterol. The hypolipidemic effects of both sugar beet pulp fiber and apple pomace fiber can be attributed to their water-soluble parts. The sugar beet pulp and apple pomace fibers have no antioxidant properties.     

仁怀市酒厂废水中重金属元素含量的测定

采用原子吸收分光光度法测定废水中重金属元素的含量并进行污染评价.结果表明:仁怀市酒厂废水呈强酸性,废水中重金属铜、铅、镉、铬、锰含量均很低,其单项污染指数远低于0.700,完全能达到国家综合污水排放一级标准.小作坊底锅水和窖底水中锌元素含量偏高,其单项污染指数大于1.000,综合污染指数大于0.700,但低于国家综合污水排放二级标准,根据单项及综合污染指数计算分析,属轻度污染等级.其他种类的废水完全达到国家综合污水排放一级标准.     

重金属复合污染对茶叶重金属、主要生化成分含量及冲泡茶汤浸出率的影响研究

通过土壤盆栽实验,研究四种重金属As、Pb、Cr、Cd复合污染对茶叶重金属含量及主要生化成分含量的影响,同时研究了不同冲泡次数下茶汤中四种重金属的浸出率。结果表明:复合污染条件下,茶叶中重金属积累量显著高于对照,其高低顺序为Pb>Cr>Cd>As,其中,Cd在盆栽土壤中的添加量低于As,但在茶叶中的积累量高于Cd,表明Cd在茶树体内的迁移率高于As。复合污染茶叶中的氨基酸和咖啡碱含量均低于对照,酚氨比值高于对照,从而降低了茶叶品质。四种重金属元素在茶汤中的浸出量均随着冲泡次数的增加而减少,Cd、Cr、Pb和As的总浸出率分别为:18.0%~35.7%、14.8%~26.8%、15.4%~31.9%和13.7%~22.1%,Pb和Cd的浸出率大于Cr和As;四种重金属元素之间的络合作用,会影响重金属在茶叶中的累积量和茶汤中的浸出量。      

Effect of heavy metals on the sorption of hydrophobic organic compounds to wood charcoal

Black carbon (BC) is believed to be an important adsorbent of organic pollutants. A complex suite of heavy metals and organic pollutants is commonly present in many situations. An issue that has received little direct attention is the effect of heavy metals on sorption of organic compounds to BC. We found that coadsorption of Cu2+ at an environmentally relevant, comparable concentration (50 mg L-1) decreases sorption of both the polar compound, 2,4-dichlorophenol (DCP), and nonpolar compounds, 1,2-dichlorobenzene (DCB) and naphthalene (NAP), by 30-60%, as measured bythe change in the distribution coefficient (Kd). This was attributed to surface complexation of CU2+ to form hydration shells of dense water that directly compete with organics for adsorption surface area. In contrast, coadsorption of Ag+ increases sorption of the organic solutes, which was accounted for by the decline in hydrophilicity of the local region around Ag+-complexed functionalities due to softness of the cation, leading to mitigated competitive sorption of water. Coadsorption of heavy metal ions to nonporous graphite, a model of the BC graphene (polycyclic aromatic) structure that has no 0-containing groups, however, only slightly inhibits organic adsorption due to the low affinities of metal ions to graphite surface. The results of the present study showed that the presence of coexisting heavy metals greatly affects sorption of organic pollutants on BC and thereby their fate and transport.