北京东郊作物土壤系统中重金属的迁移、分布、积累

 本文研究了北京东郊污灌区重金属在作物—土壤中的迁移、分布、积累规律,证实本区蔬菜中汞含量比粮食作物约大3—15倍,比水果约大6—200倍。麦粒、糙米中的Cu、Hg、Cd、Pb、Ni的含量与土壤含量相关性不显著。架豆中重金属含量与土壤中重金属含量的相关性,只有Zn,Pb达显著水平。白菜土有机质含量与重金属含量相关性达显著水平,而白菜的重金属含量与土壤的重金属含量相关性却不显著。说明除了土壤中重金属的总量外,有效态含量的多少,是影响本区作物吸收积累重金属的主要因素。 本区施污泥的土壤和生长的作物Cd／Zn大部小于1%、盆栽试验证明：施用本区污泥污水对水稻生长发育的影响比施污泥灌清水的影响大些,因此,施用含重金属污泥时,最好不要超过5000斤／亩。大田和室内模拟试验证明：重金属从土壤中迁移到植物,由植物带走输出的量极少,其中以带走输出的Hg、Cd,As相对较多,带走输出的Pb、Cr相对的少些。     

磷在羊草草地植物－土壤中积累、分布及转移规律

本文在研究磷素几种形态的动态变化基础上,运用生态系统理论,利用系统分析的方法,分析了磷在植物－土壤系统中的流通、积累和归还的特点,得出如下结果：１．磷素在系统内９９％以上分布在土壤中。２．群落内磷的再利用量为３．６７５５ｋｇ·ｈａ￣（－１）·ｙｒ￣（－１）。３．群落每年吸收的磷为３．４０６３ｋｇ·ｈａ￣（－１）·ｙｒ￣（－１）,地上部归还土壤为０．１４４７ｋｇ·ｈａ￣（－１）·ｙｒ￣（－１）,地下部归还土壤为１．８１１１ｋｇ·ｈａ￣（－１）·ｙｒ￣（－１）,输出仅占吸收量的４２．２４％,磷素在群落中每年净积累为０．３５ｋｓ·ｈａ￣（－１）·ｙｒ￣（－１）。４．磷在各库内的周转时间是：地上植物活体为１．３３６４年,立枯体为６．４３５０年,活根为１．０８８７年,死根为２．４３７８年,有机磷为８３３．３年。     

锌在红树植物白骨壤－土壤系统中的分布与迁移

河口海湾沉积物中锌的污染已对水生生物构成了潜在的威胁.本研究在温室中建立红树植物白骨壤的模拟湿地系统,分别用不同浓度的人工配置污水和人工海水(对照)每周定时、定量地对模拟湿地系统进行为期1年的污灌试验,研究污水中的重金属锌在红树植物白骨壤-土壤系统中的分布、累积与迁移规律.结果表明,由人工污水加入模拟系统中的锌主要存留在土壤中(大于67%),只有一小部分(1.24%～10.4%)迁移到植物体和凋落物中,即白骨壤-土壤系统对生活污水中的锌具有较强的净化作用.根据物质平衡模型进行的计算表明,土壤子系统中锌的环境容量较大.     

镉在土壤-植物-人体系统中迁移积累及其影响因子

环境镉(Cd)污染对微生物、植物、动物和人体均可产生较大的危害。食物链是镉对普通人群造成健康危害的主要途径之一。污染土壤中的镉通过植物根系吸收与体内转运最终在植物可食部分中积累。Cd通过食物链进人人体并在体内蓄积受许多因素的影响,这些影响因素主要有3个方面：土壤性质(土壤含镉量、pH、有机质、粘土矿物和土壤养分状况),植物特性(包括基因型差异、根际过程和植物生理机制)和人体微量元素营养状况等因素。本文就镉在食物链中迁移积累及其调控机理的研究进展进行简要的综述。     

半干旱区农田土壤无机氮积累与迁移机理

研究黄土旱塬区长期定位试验中 1 0个典型处理土壤剖面 (0～ 30 0 cm)水分和无机氮的季节变化 ,探讨在半干旱区农田无机氮的积累与迁移机理。结果表明休闲处理除表层外土壤剖面的水分、硝态氮和铵态氮的含量分别稳定在 1 7%～ 2 0 %、4～ 7mg N/kg和 6～ 1 0 mg N/kg土的范围。种植作物显著地改变土壤剖面水分和硝态氮的分布状况 ,并使其含量发生大幅度的季节变化。作物利用限制了农田土壤硝态氮向深层的迁移。小麦连作无化肥氮处理及苜蓿连作不施肥或氮、磷加有机肥处理土壤硝态氮主要集中在 0～ 40 cm土层。小麦连作单施氮肥 (1 2 0 kg N/(hm2· a) )处理经 1 7年后土壤剖面硝态氮积累总量达到施氮总量的55% ,40～ 60 cm和 1 4 0～ 2 2 0 cm土层出现两个高峰 ,并表现出随季节性变化向土壤深层迁移的趋势。氮肥与磷肥或有机肥施用大幅度减少了土壤剖面硝态氮积累 ,并使其限制在 1 60 cm以上的土层内 ,2 0 0 cm以下土层的硝态氮含量极低 (<1 mg N/kg土 ) ,因而不具向深层迁移的条件。土壤剖面的铵态氮含量不受作物、施肥和季节性气候变化的影响     

磷在羊草草地植物——土壤中积累、分布及转移规律

 本文在研究磷素几种形态的动态变化基础上,运用生态系统理论,利用系统分析的方法,分析了磷在植物—土壤系统中的流通、积累和归还的特点,得出如下结果：1．磷素在系统内99%以上分布在土壤中。2．群落内磷的再利用量为3.6755kg·ha-1·yr-1。3．群落每年吸收的磷为3.4063kg·ha-1·yr-1,地上部归还土壤为0.1447kg·ha-1·yr-1,地下部归还土壤为1.8111kg·ha-1·yr-1,输出仅占吸收量的42.24%,磷素在群落中每年净积累为0.35kg·ha-1·yr-1．4．磷在各库内的周转时间是：地上植物活体为1.3364年,立枯体为6.4350年,活根为1.0887年,死根为2.4378年,有机磷为833.3年。     

土壤－植物系统中多环芳烃和重金属的行为研究

对土壤中多环芳烃和重金属的行为研究表明,与对照相比,０—２０ｃｍ以上表土层存在多环芳烃和重金属积累,２０ｃｍ以下土层未发现积累;与春、秋两次采样结果相比,土壤中多环芳烃的含量有所下降,表明土壤微生物对多环芳烃有一定降解作用,且其降解程度与土壤－植物系统的生态结构有关．菲在地下水中检出浓度较高,表明这一污染物有向下迁移的可能性．此外,柳树对土壤中重金属Ｃｄ的积累有明显的削减与净化作用．本研究表明,严格限制污水中多环芳烃和重金属的污染负荷以及设计合理的生态结构是避免多环芳烃和重金属在土壤中积累的关键．     

石油烃降解物对Cd在土壤－植物系统中迁移转化影响的研究

研究棕榈酸、儿茶酚和香草酸对土壤中Ｃｄ行为的影响表明,土壤中儿茶酚对水稻的毒害浓度为１００ｍｇ·ｋｇ－１,而香草酸则为５００ｍｇ·ｋｇ－１．当土壤中儿茶酚为５０００ｍｇ·ｋｇ－１时,水稻籽实中Ｃｄ浓度降到０．００８ｍｇ·ｋｇ－１,土壤淋溶液中Ｃｄ浓度降为０．００５ｍｇ·Ｌ－１,３种有机物均能增加土壤中有机结合态Ｃｄ的比例,５０００ｍｇ·ｋｇ－１的儿茶酚处理,土壤中有机质结合态Ｃｄ占总Ｃｄ的４８．７１％．     

贵州万山汞矿地区的植物及植物积累汞的研究

本文分析了矿区地表异常地段的土壤汞水平和植物群落,提出了自然条件下划分野生植物含汞水平标准,并研究了它们积累汞的规律。在大气含汞量极高的情况下,强富汞植物,弱富汞植物和中富汞植物都相应增加体内的汞积累。野菊花,大叶胡枝子,牛筋树可以作为大气汞污染物的净化植物。矿区农田土壤含汞量较高,农作物可食部位的含汞量都超标,菜蔬类尤为严重。在植物群落汞积累与环境因子关系的探讨中,认为草本植物和部分灌木的汞积累与下层土壤有机质和坡向关系密切,木本植物老枝含汞量受下层土壤含汞量的控制,也受土壤干湿度的影响。     

土壤—植物系统中水流阻力变化和分布规律的研究

以植物根系吸水的人工模拟试验测得资料为依据,运用水流的电模拟原理,定量分析了不同土壤水分水平处理下土壤-植物系统中水流阻力各分量的大小、变化规律及其相对重要性．结果表明,土壤阻力（Rs）、根内木质部传导阻力（Rc）随生任时间的推移而减小,随土层深度的加深而增大,土根接触组力（Rsr）、根系吸收阻力（Rr）、土壤-植物系统中水流总阻力（RA）随时间表现出先下降后上升阶段的动态变化特征,Rs、Rc、Rsr、Rr、RA均随土壤湿度减小而大幅度增大;在土壤-植物系统水流阻力各分量中,Rr占RA的比例为55～96％,Rsr约占RA的4－45％,而Rs、Pc相对可忽略不计,故Rr,是决定液态水流速率的重要因素．     

The Distribution of Mercury in the Sediments of Eight Saskatchewan Lakes

Eight lakes located in the southern half of Saskatchewan were sampled in May and June, 1987, to determine the concentration and spatial distribution of mercury in their surface sediments. Katepwa and Buffalo Pound lakes had maximum total mercury sediment concentrations of 0.158 and 0.100 μg · g⁻¹ dry weight respectively, while in the other six lakes the mercury concentration was never greater than 0.04 μg · g⁻¹ dw. Despite this difference in mercury concentration in the sediments of the lakes, walleye sampled from them have high mercury concentrations exceeding 0.5 μ · g⁻¹ (wet weight).     

钝顶螺旋藻富集转化硒及硒在藻体中的分布

钝顶螺旋藻在４℃、避光、隔离空气条件下,对硒的吸附量死体显著高于活体。藻体对硒的最大富集量为６２７．４μg.g^-1(DW),培养基中硒浓度在３００μg.ml^-1以下时有机硒转化率大于８０％。藻体中的硒主要分布在水溶性组化率大于８０％。藻体中的硒主要分布在水溶性组分中,占总硒的６５％以上,蛋白质硒占有机硒的７１．９％,多糖、核酸也有一定量硒分布。     

酚、氰在凤眼莲-水体系统中的迁移、积累及净化

利用高等水生植物净化污水具有成本低、花工少、简单易行等特点,便于在工厂中应用和推广。国内,在实验条件下,利用高等水生植物净化污水已见有报道,但具体应用于生产条件下尚少见有关报道。本研究着重于在工厂生产条件下,了解高等水生植物凤眼莲(Eichhornia crassipes)对钢铁厂焦化车间直接排放出的含酚、氰污水的净化效应,以及酚、氰在植物——水体系统中的吸收、运转和积累情况。     

Cadmium Pollution and its Transfer in Agricultural Systems in the Suburbs of Tianjin,China

Cadmium (Cd) pollution in the suburbs of Tianjin, China, was monitored over a period of several years. During this period, 193 soil, 120 vegetable, and 71 rice samples from four suburban districts were analyzed. The Cd content of the soil samples was considerably higher than the background level. Some soil samples from the Dongli and Xiqing districts were even in the S5 (Heavy) and S6 (Severe) pollution levels, with a maximum concentration of 5.20 mg kg^?1. The Cd contents of vegetable and rice samples were found to be in the F3 (Intermediate) and F4 (Heavy) pollution levels. Vegetables showed differing abilities to accumulate Cd and can be ranked in the following order: leaf vegetables > rootstalk vegetables > fruit vegetables. The average Cd level in different vegetables ranged from 0.0064 to 0.132 mg kg^?1, and a positive relationship (p < 0.05) was found between soil and plant Cd contents. Chinese cabbage and celery were more likely to pose risks to human health, as shown by their higher hazardous quotient (HQ) values. The soil Cd pollution in Tianjin seemed primarily to be caused by wastewater irrigation and the application of sewage sludge to farmlands. Other possible sources include the use of phosphate fertilizer and atmospheric deposition.     

铬在南瓜体内的分布与积累

采用^51Cr同位素标记法检测富铬南瓜品种‘永安2号’在不同发育时期对^51Cr的吸收和分配的结果表明：苗期（8片叶）,南瓜地上各部分^51Cr放射性强度的相对比例分别为：叶64．4％,茎30．2％,花5．4％,主要分布在距根部较近的叶片和茎中,幼叶中含量很低;幼果期分别为：果肉51．1％,叶片41．6％,茎4．8％,花2.4％,主要分布在果肉和中部叶片中。     

Antimony in the Soil-Plant System in an Sb Mining/Smelting Area of Southwest China

The distribution, bioavailability, and accumulation of antimony (Sb) at the interface of rhizospheric soils and indigenous plants from a large Sb mining/smelting area in Southwest China were explored. Results showed that the local soil was severely polluted by Sb, and the aluminum magnesium silicate minerals and the carbonate fraction may mainly contribute to bound Sb. The sequential extraction results of soil samples revealed that the portion of bioavailable Sb was low, but the bioavailable Sb concentration was up to 67.2 mg/kg, due to high total Sb concentrations in the soil. The Sb content in local plants showed a wide range, from 21 to 21148 mg/kg. The species of Chenopodium album Linn., Sedum emarginatum Migo, and Sedum lineare Thunb showed high accumulation of Sb at levels of above 1000 mg/kg. The Sb contents in the tissues for most plants decreased with the order of root > leaf > stem. The bioaccumulation coefficients and/or the biological transfer factors for most plants were less than 1. All of the studied plant species were not identified as Sb-hyperaccumulators, but the species of Chenopodium album Linn., Sedum emarginatum Migo, and Sedum lineare Thunb could be applied as alternative plants for phytoremediating Sb-polluted soils.     

汞与硒在不同汞暴露水平地区猪肝脏和肾脏蛋白质中的分布

通过对贵州万山汞污染地区及北京地区猪肝脏和肾脏组织上清液进行凝胶过滤色谱分离(SephadexG 10 0 ) ,随后用原子荧光法测定它们蛋白质组分中汞和硒的含量 ,研究在汞暴露水平不同状态下微量元素汞和硒在动物体蛋白质分子水平上的分布 .发现这两个地区猪肝脏和肾脏组织上清液蛋白质组分中汞和硒的分布模式有明显差异 .贵州万山汞污染地区猪肝脏上清液中汞浓度比北京地区高 ,硒浓度也相应高 ,且前者与高分子量和低分子量蛋白结合的硒均明显高于后者 ;而北京地区猪肝脏上清液中的硒主要以与高分子量蛋白结合的形式存在 .贵州汞污染地区猪肝脏上清液中汞主要与高分子量蛋白结合 ,而北京地区猪肝脏上清液中汞则分布较为均匀 .贵州万山地区猪肾脏上清液中 ,含硒峰在高分子量蛋白区和低分子量区都有分布 ;而北京地区猪肾脏上清液中 ,硒则主要集中分布于高分子量蛋白范围 .这两个地区猪肾脏上清液中都有分子量约为 11kD的金属硫蛋白 (MT)存在 ,北京地区猪肾脏上清液中汞主要以与金属硫蛋白结合的形式出现 ,而贵州万山地区猪肾脏上清液中的汞除与金属硫蛋白结合外 ,尚有相当大部分是以与高分子量蛋白结合的形式存在 .研究结果表明 ,由于这两个地区汞暴露水平的差异 ,不仅使这两地区猪肝、肾上清液中的汞与硒含量     

Accumulation of Mercury in Ovaries of Mice After the Application of Skin-lightening Creams

Skin-lightening creams are being increasingly used by women in particular, worldwide in an attempt to whiten their skin. Men and older people use these creams to remove age spots or other pigmentation disorders. Several studies have reported the presence of high mercury levels in skin-lightening cream. Women, especially pregnant and nursing mothers, who use these creams are at risk of mercury toxicity because long-term exposure can cause permanent neurological damage, nephrological disorders, fertility problems, and birth defects. Early exposure usually has no clinical symptoms. Mercury levels were measured in a total of 49 ovary tissue samples. The mean mercury contents in the ovaries of non-treated mice (11.70 ± 13.38 ng/g) were compared to mice treated with Rose skin-lightening cream samples (2,471.92 ± 1,336.31 ng/g) and those treated with Fair & Lovely skin-lightening creams (58.47 ± 39.51 ng/g). The mercury content in the ovary tissues increased with number of cream applications and were highest in the ovaries of mice treated twice a day with Fair & Lovely (87.79 ± 26.20 ng/g) and once a day with Rose (3,515.61 ± 1,099.78 ng/g). Our data indicate that dermal exposure to mercury can result in a significant accumulation in the ovaries of mice following the application of skin-lightening cream. This may cause alterations in reproductive behavior and contribute to infertility or ovarian failure. Of course, these results need to be confirmed by further research. Imported or locally made skin-lightening creams are widely available in Saudi market. It would be ideal to ban the sale of these creams but unfortunately, advertisements in the mass media presenting celebrities and beauty specialists make these products more popular. Alternatively, public health authorities should encourage more reliance on prescribed creams for the treatment of skin pigmentation problems.