Toxicokinetics/toxicodynamics links bioavailability for assessing arsenic uptake and toxicity in three aquaculture species

The purpose of this study was to link toxicokinetics/toxicodynamics (TK/TD) and bioavailability-based metal uptake kinetics to assess arsenic (As) uptake and bioaccumulation in three common farmed species of tilapia (Oreochromis mossambicus), milkfish (Chanos chanos), and freshwater clam (Corbicula fluminea). We developed a mechanistic framework by linking damage assessment model (DAM) and bioavailability-based Michaelis?CMenten model for describing TK/TD and As uptake mechanisms. The proposed model was verified with published acute toxicity data. The estimated TK/TD parameters were used to simulate the relationship between bioavailable As uptake and susceptibility probability. The As toxicity was also evaluated based on a constructed elimination?Crecovery scheme. Absorption rate constants were estimated to be 0.025, 0.016, and 0.175?mL g^?1 h^?1 and As uptake rate constant estimates were 22.875, 63.125, and 788.318?ng g^?1 h^?1 for tilapia, milkfish, and freshwater clam, respectively. Here we showed that a potential trade-off between capacities of As elimination and damage recovery was found among three farmed species. Moreover, the susceptibility probability can also be estimated by the elimination?Crecovery relations. This study suggested that bioavailability-based uptake kinetics and TK/TD-based DAM could be integrated for assessing metal uptake and toxicity in aquatic organisms. This study is useful to quantitatively assess the complex environmental behavior of metal uptake and implicate to risk assessment of metals in aquaculture systems.     

Ti/BDD/PbO_2复合电极在化学需氧量测定中的应用

以钛基掺硼金刚石为基体,采用电沉积的方法制备了Ti/BDD/PbO2复合电极,并将其用于化学需氧量（COD）的测定。采用扫描电子显微镜（SEM）和X射线衍射谱图（XRD）表征了电极的微观形貌及结构,采用电化学工作站考察了电极对有机物响应特性。实验结果表明,在1.45 V的低电位条件下,线性范围为0.5～175 mg/L,检测限为0.3 mg/L（S/N=3）。采用Ti/BDD/PbO2复合电极测定法和重铬酸钾标准方法对市政污水、食品废水及印染废水的对比结果表明,2种方法的相对误差小于10%,具有良好的一致性。     

改性TiO_2光催化降解三苯甲烷类污染物

以硫酸钛为原料采用水热法制备了掺Fe3＋TiO2晶体粉末,采用X射线衍射仪（XRD）对样品的结构进行了表征。在可见光条件下,用溴酚蓝、甲基绿、甲基蓝、孔雀石绿、甲基紫和碱性品红等6种典型三苯甲烷类化合物为目标降解物,研究了以自制的掺Fe3＋TiO2晶体粉末对它们的催化降解作用。实验结果表明,制备的掺Fe3＋TiO2晶体属于锐钛矿型。6种化合物的光催化降解反应遵循拟一级动力学规律,且可用Langmuir-Hinshelwood（L-H）动力学模型描述,其表观反应速度常数（k）的大小顺序为：溴酚蓝〈甲基绿〈甲基蓝〈孔雀石绿〈甲基紫〈碱性品红,大小变化次序与其半衰期t1/2成反比,并从分子结构上对它们的降解规律进行定性解释。     

螺、蚌对污水处理厂再生水环境的改善稳定作用

通过选用昆明市第五污水处理厂的一级A标出水和水处理厂外排污泥作为静态实验环境,研究不同混养密度下铜锈环棱螺、椭圆背角无齿蚌对污水处理厂再生水环境的净化性能,筛选出净化效果较好的放养密度。结果表明:放养30 d,铜锈环棱螺、椭圆背角无齿蚌对污水处理厂再生水环境的水质、底质均有一定的净化作用,扣减空白对照影响,水中COD、TP、NH3-N及底泥有机质平均去除率分别为22.26%、26.10%、25.60%和25.69%,底泥厚度平均减少3.8 cm;与对照相比,放养螺蚌45 d内水均能清澈见底,透明度均>70 cm,能明显稳定水体透明度,改善水环境。综合螺蚌生长适应性和净化效果考虑:污水处理厂再生水静态环境中,螺蚌混养密度应≤3 000 g/m3,在2 000～2 500 g/m3为宜,其中铜锈环棱螺的最适放养密度在400 g/m3,椭圆背角无齿蚌为1 600～2 100 g/m3。     

人工浮床对汾江河水质净化的研究

对佛山市汾江河内布置浮床的水域的7个断面进行采样监测,分析了布置浮床侧与未布置浮床侧各水质指标的差异,以考察人工浮床对汾江河水质的净化效果。同时比较了圆币草、水罂粟、梭鱼草、狐尾草、美人蕉和鸢尾6种浮床植物的生物量和氮磷吸收量。结果表明,布置人工浮床一侧的水质TN、TP、COD和NH4＋-N含量均显著低于未布置浮床一侧的水质,表明人工浮床对水体水质的有净化效果。总面积约4 900 m2的浮床植物经过3个月的生长,从水体中共吸收了192.5 kg的氮和76.1 kg的磷。6种浮床植物中,狐尾草的净增生物量最高,达到64.2 kg/m2;圆币草次之,为62.2 kg/m2。狐尾草和圆币草对氮磷的吸收能力在6种植物中处于较高水平,每平方米狐尾草和圆币草从水体中分别吸收了51.61g氮、19.79 g磷和46.90 g氮、22.93 g磷。综合比较得出,狐尾草和圆币草在生物量和氮磷吸收量上均保持在较高水平,是较好的浮床植物。本研究为人工浮床在南方类似河流中的应用及植物选择提供了参考依据。     

不同质量浓度苦草对铜绿微囊藻生长及抗氧化酶系统的影响

采用苦草（Vallisneria spiralis Linn.）和铜绿微囊藻（Microcystis aeruginosa）共生培养的实验方法,通过追踪测定铜绿微囊藻的生物量、叶绿素a含量、丙二醛（MDA）含量、超氧化物歧化酶（SOD）和过氧化物酶（POD）活性,研究了不同质量浓度苦草对铜绿微囊藻生长及抗氧化酶系统的影响。结果表明,质量浓度大于10 g/L时,苦草对铜绿微囊藻有明显的抑制作用,表现为苦草质量浓度为10、20和40 g/L时,第15天对铜绿微囊藻的抑制率分别为63.3%、94.7%和99.8%,培养过程中,铜绿微囊藻的叶绿素a含量逐渐减少,而SOD、POD活性及MDA含量呈现先增加后逐渐降低的趋势,表明苦草释放的化感物质在经过一定时间积累后能够明显抑制铜绿微囊藻SOD和POD的活性,引起细胞的氧化损伤,促进叶绿素的分解,从而导致藻类死亡,这是苦草抑制铜绿微囊藻生长的原因之一。     

Environmental lead pollution threatens the children living in the Pearl River Delta region, China

Introduction and purpose

The objective of this study is to determine children??s blood lead levels and identify sources of lead exposure. Childhood lead exposure constitutes a major pediatric health problem today in China. A blood lead screening survey program for children in the age group of 2?C12?years residing in Pearl River Delta region, south of China, was carried out from Dec 2007 to Jan 2008.

Methods

Blood lead levels and lead isotope ratios of a total of 761 participants were assessed by inductively coupled plasma mass spectroscopy. Measurements of urban environmental samples for source identification of children lead exposure were also performed.

Results and conclusions

The geometric mean value of the children??s blood lead levels was 57.05???g/L, and 9.6% of them were higher than 100???g/L. The blood lead levels were still much higher than those in developed countries. Based on the data of environmental lead source inventories, lead isotopic tracing revealed that there is about 6.7% past used gasoline Pb embedded in Shenzhen residential dust and about 15.6% in Guangzhou dust, respectively.     

Historical change of mercury pollution in remote Yongle archipelago, South China Sea

We collected three ornithogenic coral sand sedimentary profiles from Jinyin Island, Jinqing Island and Guangjin Island of Yongle archipelago, South China Sea and reconstructed the deposition flux of anthropogenic Hg over the past 700 years in the study area. On the whole, the anthropogenic Hg flux is relatively low; it remained at a low level before the Industrial Revolution with a small peak at about 1450-1550 AD, which may record the enhanced metallurgy activity in Ming Dynasty of China. During the 20th century, the deposition flux of anthropogenic Hg increased rapidly, but two troughs occurred during the periods around 1940s and 1970s, corresponding to the economic depression caused by World War II, Civil War in China (1945-1949), and the Culture Revolution (1966-1976) in China. Since the 1970s the deposition flux of anthropogenic Hg has been persistently increasing, apparently the result of fast economic development in East and Southeast Asia countries around South China Sea.     

Textural and chemical properties of swine-manure-derived biochar pertinent to its potential use as a soil amendment

Biochars have received increasing attention in recent years because of their properties pertaining to soil fertility and contaminant immobilization as well as serving as carbon sinks. In this work, a series of biochars were produced from dried swine manure waste by slow pyrolysis at different temperatures (i.e., 673-1073 K). The characterization of the resulting biochars was examined for its relevance to its potential use as soil amendment. It was found that the pore properties, ash contents and pH values of all swine-manure-derived biochars basically increased as temperature increased, while the yield and nitrogen/oxygen contents decreased with increasing temperature as a result of pyrolytic volatilization during pyrolysis. From the organic and inorganic elements analyses, the manure-derived biochar was rich in soil nutrients such as N, P, Ca, Mg, and K. Furthermore, the pore, surface and chemical properties were also consistent with the observations of the SEM-EDS, XRD and FTIR. This result suggested that the mesoporous manure-derived biochar could be used as an excellent medium to soil environment.     

高效聚合氯化铝对超滤膜污染影响的中试研究

针对某水厂以超滤为核心的短流程水处理工艺,在通过聚氯乙烯(PVC)超滤膜之前选择不同投加量(5、10、15和20 mg/L)的高效聚合氯化铝(HPAC)对长江下游原水进行混凝处理。通过跨膜压差(TMP)增长趋势、CODMn的去除率以及混凝后的水质,可知HPAC的最优投加量为15 mg/L。在此投加量下,运用体积排阻色谱法分析原水、膜前水、膜后水中各相对分子质量有机物的变化,可以发现混凝去除有机物的效果要优于超滤截留的。继而将HPAC与另外4种常用混凝剂:硫酸铝(分析纯)、氯化铁(化学纯)、聚合氯化铝(PAC)、聚合硫酸铁进行对比,结果表明,在它们各自最优投加量下,HPAC能够更有效地减缓超滤膜TMP的增长率,从而降低膜污染。因此,认为HPAC是与PVC超滤合金膜契合效果最佳的混凝剂。