铬在小鼠体内的蓄积效应与毒性

铬的工业用途很广,主要用于金属加工、电镀、制革等行业,这些行业排放的三废导致了环境铬污染,对环境生态和人体健康造成危害。为探究铬对动物的毒性作用,选择昆明种纯系小白鼠作为受试生物,研究六价铬在小鼠体内的蓄积效应及毒性。结果显示,饮用水中一定浓度的六价铬(15~70 mg·L-1)可抑制小鼠体重的正常增长,染毒30 d后,小鼠肝脏和肾脏脏器系数下降,脾脏和脑的脏器系数提高;总铬含量在心脏和脾脏中增高,其他脏器中无明显蓄积效应;铬染毒组小鼠骨髓细胞活性氧水平提高,骨髓嗜多染红细胞微核率显著增高。结果表明,通过饮水摄入六价铬可造成小鼠肝肾损伤,心脏和脾脏内铬蓄积,并通过活性氧损伤效应破坏机体的遗传稳定性。     

酸雨淋溶对铬渣中Cr6+释放的影响

采用人工柱对3个不同年代的铬渣进行为期5年不同pH值(4.0,5.0,6.0)下的模拟酸雨淋溶实验,结果表明:淋溶前铬渣具有很强的腐蚀性,pH值达到12以上,总铬和Cr6 分别占铬渣的4.68%-4.86%和1.19%-1.73%;Cr6 溶出浓度在淋溶初期大,随着淋溶时间的增加,溶出浓度急剧下降,淋溶接近第二年雨量时,溶出浓度减小且趋于稳定.5年模拟酸雨淋溶后,Cr6 累积溶出范围在2138-4490mg,浸出液浓度稳定范围50-127mg·l-1,仍然远高于排放标准.铬渣淋溶后,残渣态和结晶铁锰氧化物结合态铬含量保持不变,水溶态、酸溶态和稳定铁锰氧化物结合态铬有不同程度减小.     

含铬污液在土壤中迁移规律的研究

通过静态吸附和动态土柱淋溶实验，研究了含铬污液中Ｃｒ（Ⅲ）、Ｃｒ（Ⅵ）在土壤中的迁移规律。结果表明，土壤对Ｃｒ（Ⅲ）、Ｃｒ（Ⅵ）的等温吸附过程均符合Ｌａｎｇｍｕｉｒ方程，土壤对Ｃｒ（Ⅲ）、Ｃｒ（Ⅵ）的饱和吸附量分别为２．１７＊１０＾４ｍｇ／ｋｇ、１７５ｍｇ／ｋｇ；动态截留量分别为７．００＊１０＾３ｍｇ／ｋｇ、５６．７ｍｇ／ｋｇ。     

碱性介质中还原高浓度Cr(Ⅵ)细菌的分离及其特性

目前国内外处理含铬废水的微生物仅局限于酸性或中性环境,且处理Cr(Ⅵ)的浓度仅为200mg L-1左右,难以工业化应用,尤其是不可能处理诸如铬渣渗滤液之类的碱性含铬废水及铬渣.本研究从铬渣堆埋场附近取得菌样,经富集、分离、驯化,得到能在碱性介质中高效还原Cr(Ⅵ)的无色杆菌属(Achromobacter sp.)菌株,该菌为G-,具有周身鞭毛及可运动性.对其生理及还原Cr(Ⅵ)的特性进行了研究,结果表明该菌嗜碱,好氧,耐盐及高Cr(Ⅵ),在有氧、pH为10.30、30℃等条件下,含Cr(Ⅵ)1 570 mg L-1的废水经该菌处理16 h后浓度降至0.6 mg L-1.处理后的沉淀物中铬以Cr(OH)3的非晶形态存在,其中总铬含量为21.44%,Cr(Ⅵ)检测不出,具有很大的回收价值.图4表3参16     

碱性介质中还原高浓度Cr(VI)细菌的分离及其特性

目前国内外处理含铬废水的微生物仅局限于酸性或中性环境,且处理Cr(VI)的浓度仅为200mgL-1左右,难以工业化应用,尤其是不可能处理诸如铬渣渗滤液之类的碱性含铬废水及铬渣.本研究从铬渣堆埋场附近取得菌样,经富集、分离、驯化,得到能在碱性介质中高效还原Cr(VI)的无色杆菌属(Achromobactersp.)菌株,该菌为G-,具有周身鞭毛及可运动性.对其生理及还原Cr(VI)的特性进行了研究,结果表明:该菌嗜碱,好氧,耐盐及高Cr(VI),在有氧、pH为10.30、30℃等条件下,含Cr(VI)1570mgL-1的废水经该菌处理16h后浓度降至0.6mgL-1.处理后的沉淀物中铬以Cr(OH)3的非晶形态存在,其中总铬含量为21.44%,Cr(VI)检测不出,具有很大的回收价值.图4表3参16     

不同价态铬在不同水分条件下的生物有效性及其对水稻的毒性

氧化还原过程在铬的形态转化中起了重要作用,而铬形态的转化能够影响其生物有效性及毒性。通过温室土培试验研究了六价铬(Cr(Ⅵ))与三价铬(Cr(Ⅲ))在淹水与不淹水条件下在土壤溶液中的动态变化及水稻对其吸收的变化。结果表明,土壤中添加Cr(Ⅲ)时,土壤溶液中检测不出Cr;而随着土壤中添加Cr(Ⅵ)浓度的增加,土壤溶液中Cr(Ⅵ)的浓度增加,但是溶液中检测不出Cr(Ⅲ);淹水处理总体上降低了土壤溶液中Cr(Ⅵ)的浓度。而土壤添加Cr(Ⅲ)、Cr(Ⅵ)和水分处理对土壤溶液p H没有显著影响,p H在7.08.0之间变动。土壤添加Cr(Ⅵ)处理的水稻中,只有90 mg·kg-1Cr(Ⅵ)淹水处理的水稻成活,而其余处理水稻没有成活。土壤中添加Cr(Ⅲ)处理,水稻幼苗生物量随Cr(Ⅲ)浓度的增加而显著降低;除了200mg·kg-1Cr(Ⅲ)处理外,其余淹水处理的水稻幼苗生物量明显高于不淹水处理的。土壤添加Cr(Ⅲ)处理的水稻,在不淹水条件下水稻空壳率比较高,淹水条件下,随着土壤中添加Cr(Ⅲ)浓度水平的增加,水稻各部位Cr含量有增加的趋势,但增加不显著,秸秆最高Cr含量达到33.80 mg·kg-1,籽粒中Cr含量最高0.30 mg·kg-1。土壤固定Cr(Ⅲ)的能力远强于Cr(Ⅵ),添加Cr(Ⅵ)处理的土壤溶液中Cr(Ⅵ)的浓度很高,对水稻表现出较强的生长抑制。     

不溶性甘蔗渣黄原酸酯(IBX)脱除废水中的铬

本文采用不溶性甘蔗渣黄原酸酯脱除废水中的铬(Ⅵ),在pH 2—3的条件下,Cr(Ⅵ)还原成Cr(Ⅲ),Cr(Ⅲ)在pH 8—9时沉淀,废水经处理后,Cr(Ⅵ)的残留浓度达到国家排放标准。     

土壤铬（VI）污染及微生物修复研究进展（Progress on Microbial Remediation of Chromium-Contaminated Soil）

在总结国内外相关研究基础上,介绍了土壤环境中铬(Cr)的污染来源、现状及其对生物的危害,阐述了Cr在土壤中的存在形态和转化机理,并重点综述了土壤重金属Cr(VI)污染的微生物修复机理:土壤中的Cr(VI)可以在微生物还原作用、生物吸附、富集等作用下降低其生物可利用性和毒性,从而达到Cr污染土壤修复的目的.此外,针对微生物修复过程中存在的问题,提出了提高微生物修复Cr污染土壤效果的措施,并对土壤Cr污染微生物修复的发展趋势进行了展望.     

污灌湿地系统土壤-植物中铬的赋存形态研究

采取逐级提取法对江苏盐城某污水灌溉湿地土壤中的铬的赋存形态以及其上生长的丰要植物芦苇的不同组织部位中的总铬进行了分析测定，并研究其生物有效性。结果表明：与对照点相比，污灌土壤中铬质最分数明显升高而受到不同程度的污染，其赋存形态质量分数由高到低顺序为残渣态（RES-）→铁锰态（（OFeMn-））→碳酸态（CARB-）→有机态（OM-）和交换态（EX-）之和。芦苇不同组织部位中铬分布研究表明根部质量分数远大于茎和叶，说明根系吸收为主要作用，而后迁移至其它易积累部位。对各种形态的铬与植物中的铬总量之间的相关性进行了分析，相关系数表明，植物中的生物富集量与各种赋存形态都有一定的线性关系，其中强有机质结合态与生物富集量具有最好的线性相关性。     

Adverse effects of chromium on amino acid levels in freshwater fish Clarias batrachus (Linn.)

Various heavy metals released into the rivers and lakes affect aquatic fauna including Clarias batrachus. Elevated levels of chromium (Cr) in aquatic organisms, especially fish, represent an ecological and human concern. Amino acid levels were estimated in five tissues (gills, liver, kidneys, muscle, and brain) of C. batrachus after 28 days of exposure to Cr. This study showed that Cr elevated levels of free amino acids in organs of fish C. batrachus, indicating a compensatory mechanism to counter sublethal metallic stress. Data suggest that the measurement of amino acids may serve as a biomarker for Cr toxicity in fish.     

Exposure Assessment of Naturally Metal Enriched Topsoils, Port Macquarie, Australia

An exposure assessment was conducted on naturally metal enriched topsoils of the city of Port Macquarie in order to establish whether the soils pose any threat to human health. Surface soils (0–10 cm depth, <2 mm) were investigated for their total, bioavailable and leachable Cr and Ni concentrations. Total metal concentrations ranged from 145 to 4540 mg Cr kg^–1 and 20 to 2030 mg Ni kg^–1, whereas soil extractions revealed low leachable contaminant concentrations (EDTA extraction: <0.1–0.2 mg Cr L^–1 and <0.1–4.7 mg Ni L^–1; acetic acid extraction: <0.1 mg L^–1 Cr and Ni). Thus the bioavailability of Cr and Ni to plants is low, the leaching of metals into ground and surface waters is insignificant and the pathways of these metal pollutants from topsoils into residents are limited to the inadvertent ingestion, inhalation and skin adsorption of soil metals. Simulated gastric experiments, using hydrochloric acid, indicated that less than 0.01% of the total Cr and 0.1–2.4% of the total Ni ingested are soluble and available, for uptake into the human body. Critical receptors, such as small children would have to ingest considerable soil quantities (> 11.8 g per day) over long periods of time to experience an appreciable risk of deleterious effects. Thus, although Cr and Ni are present in high concentrations, the effective uptake of Cr and Ni from soil by the majority of residents is insignificant. The possibility that the Ni enriched topsoil induces allergic contact dermatitis in sensitised individuals remains to be evaluated.     

Influence of iron plaque on chromium accumulation and translocation in three rice (Oryza sativa L.) cultivars grown in solution culture

Hydroponic experiments were conducted to investigate the role of iron plaque on root surface in chromium accumulation and translocation in three rice cultivars (90-68-2, CDR22 and Jin 23A). Rice seedlings were grown under 1.0 mg L^?1 trivalent chromium (Cr(III)) stress with and without phosphorus (P) treatments. P addition significantly increased the shoot and root biomass in all three rice cultivars. In the absence of P, the amounts of iron plaque (DCB-extractable Fe) on the root surface increased resulting in the increase of Cr accumulation in iron plaque. Compared to that with P treatment, Cr concentrations in iron plaque without P treatment were enhanced by 2–3 folds in the three rice cultivars. There was a significantly positive correlation between DCB-extractable Cr and DCB-extractable Fe on the root surface of the three rice cultivars. There were no significant effects on Cr concentration in roots and shoots between P treatments, but significant differences among cultivars were observed. Cultivar Jin 23A had the lowest Cr concentration both in roots and shoots regardless of P treatment. The results suggest that iron plaque could be a trap for immobilising Cr from environment but may not affect Cr uptake and translocation. Screening and breeding the cultivars with low Cr accumulation is considered as the most effective approach in Cr contaminated areas.     

硝化褐煤对铬离子溶液的吸附研究

利用硝酸与龙口褐煤反应制得硝化褐煤，使其有效吸附质腐植酸含量提高。用该湖化褐煤对铬离子进行吸附试验，研究吸附剂的吸附量、吸附动力学、吸附模型和溶液的pH值对吸附的影响。结果表明：硝化褐煤对铬离子具有良好的吸附特性，其静态等温吸附符合Langmuir等温议程。     

掷孢酵母吸附去除铬的性能研究

通过菌种培养、分离与筛选 ,获得一株对铬具有很强还原与吸附性能的掷孢酵母(Sporobolomycetaceaesp ) .该菌株适宜的吸附pH值是 6— 9,1g培养 60h的菌体在 2 0mlpH 7的 1 5mg·l- 1 铬液中 ,吸附 8h后 ,对铬的去除率最高达到 1 0 0 % .在浓度分别为 1 5 ,30 ,5 0 ,1 0 0 ,30 0mg·l- 1 的铬液中 ,每克菌体对铬的吸附量与对数曲线y=1 72 5 8ln(x) - 2 0 9 49相吻合 ,相关系数为 0 9889,对吸附后菌体破壁测得细胞质内含铬量最高 ,达 65 5 % .通过扫描电子显微镜发现 ,处理 1 5mg·l- 1 铬液 8h后 ,菌体细胞壁的表面结构不发生形态变化