Simple Model of Dissolved Oxygen Consumption in a Bay within High Organic Loading: An Applied Remediation Tool

San Vicente Bay is a coastal shallow embayment in Central Chile with multiple uses, one of which is receiving wastewater from industrial fisheries, steel mill effluents, and domestic sewage. A simulation model was developed and applied to dissolved oxygen consumption by organic residues released into this embayment. Three compartments were established as function of: depth, circulation and outfall location. The model compartments had different volumes, and their oxygen saturation value was used as baseline. The parameters: (a) BOD₅ of the industrial and urban effluents, (b) oxygen demand by organic sediments, (c) respiration, (d) photosynthesis and (e) re-aeration were included in the model. Iteration results of the model showed severe alterations in Compartment 1, with a decrease of 65% in the oxygen below saturation. Compartment 2 showed a small decline (10%) and compartment 3 did not show apparent changes in oxygen values. Measures recommended for remediation were to decrease the BOD₅ loading by 30% in the affected sector. Iteration of the model for 200 h following recommendations derived from the preceding results produced an increase in saturation of 60% (5 ml O₂ L⁻¹), which suggested an improvement of the environmental conditions.     

Diflubenzuron residue and persistence on an oak forest after aerial application

Abstract

A twenty hectare forest block in central Pennsylvania was aerially sprayed with diflubenzuron (Dimilin 25W®) at the dose of 33.23g A.I./ha in 9.4 litres/ha. Leaf samples were collected from the upper and lower canopies of 27 oaks and understory within this block on the day of spray, May 29, 1991. Canopy leaves were also collected on May 31, June 10, July 29 and September 26, 1991.

Recovery of diflubenzuron residues on fortified canopy‐leaf and litter‐leaf samples using analytical techniques employed in this study averaged 87.4% (SE = 7.5%) and 66.2% (SE = 8.2%), respectively.

On the day of spray, diflubenzuron residues on the upper canopy, lower canopy and understory averaged 81.18, 39.65 and 8.35 ng/cm², respectively. Diflubenzuron residues on canopy‐leaf samples collected 2, 12, 61 and 120 days post‐spray averaged 14.83 (SE = 10.19), 16.75 (SE = 9.95), 12.84 (SE = 8.25) and 11.20 (SE = 7.52) ng/cm², respectively. Diflubenzuron residues on litter‐leaf samples collected after leaf senescence ‐ 169 and 323 days post spray contained measurable amounts of diflubenzuron in 51 and 59% of the samples, respectively. Of the samples with measurable amounts of diflubenzuron, residues averaged 1.36 (SE = 2.44) and 0.65 ng/cm² (SE = 0.73) respectively.     

600 MW机组低压转子叶片裂纹分析

针对某台600 MW亚临界参数汽轮机低压转子的末三级叶片(2Cr12NiMo1W1V钢)出汽侧裂纹进行了宏观形貌观察、化学成分分析、金相组织分析、室温冲击韧性试验、硬度试验,并对断口进行了扫描电镜及能谱分析。结果表明：此次开裂的低压转子叶片,是由于其化学成分Mo元素含量低于标准要求,导致材料的KISCC降低,以及硬度偏低造成裂纹扩展所需的外界启动应力降低,进而在运行过程中拉应力和湿蒸汽的氧化腐蚀共同作用下,发生了应力腐蚀开裂。     

家蚕斑纹限性品种SC_1的RAPD差异DNA片段的克隆及其酶切图谱分析

利用RAPD技术对家蚕限性普斑品种SC1的雌雄体分别进行PCR扩增通过120种引物的筛选,得到1个雌体特异的RAPDDNA片段将该片段克隆到pUC19质粒,井进行了限制性内切酶图谱分析.     

广州市白云山降水的化学特征及源解析

以2006年广州市白云山降水监测资料为基础,对其降水样品的化学特征进行了分析。结果表明,白云山降水样品pH值分布为3.04—6.41,雨量加权pH平均值为4.26,酸雨频率为70.2％,降水中的主要阳离子是Ca^2＋和NH^＋4分别占阳离子总量的46.4％和17.5％;主要阴离子为SO^2-4和NO^-3,分别占阴离子总量的59.0％和19.9％。相对酸度（FA）和中和因子（NF）计算结果表明,约有84.7％的降水酸度被碱性成分Ca^2＋和NH^＋4中和。利用富集系数方法,计算结果表明SO^2-4和NO^-3主要来源于人类活动,而Ca^2＋和K^＋主要来源于岩石／土壤风化。     

俚岛湾海域砷的分布特征及污染评价

以威海俚岛湾养殖区为研究对象,调查研究了俚岛湾海域表层海水和沉积物中总砷的分布特征,并综合评价了砷的污染状况及潜在生态风险。俚岛湾海域表层海水总砷浓度为1.78~2.78μg/L,平均浓度为2.20μg/L,比大洋水略高,俚岛湾海域海水水质较好,未受到砷污染;海水中砷的季节变化为夏季较高、秋冬季基本稳定、春季最低。俚岛湾海域表层沉积物中砷的平面分布呈现出由近岸向远岸降低的趋势,砷含量的年际变化甚微,基本保持稳定的水平;采用潜在生态风险指数法和重金属质量基准法对沉积物进行评价。评价结果表明,该海域表层沉积物中砷污染水平较低,属于低潜在生态风险。     

渤海湾入海溶解无机氮总量控制研究

基于渤海湾近岸海域的实际调查结果,采取生态物理耦合模型,对渤海湾的主要污染物-溶解无机氮(DIN)的基准环境容量和极小剩余海洋环境容量进行了计算。结果表明,渤海湾DIN的极小剩余海洋环境容量在Ⅰ类和Ⅱ类水质标准下均为负值,渤海湾的DIN已经超标。结合实际的海水功能区水质管理目标,应重点控制非点源的排放,加强上游携带入境污染物的处理,从总量上控制DIN入海污染通量,改善渤海湾水质。     

Application of statistical modeling to optimize a coastal water quality monitoring program

The long-term water quality monitoring program implemented by the Massachusetts Water Resources Authority in 1992 is extensive and has provide substantial understanding of the seasonality of the waters in both Boston Harbor and Massachusetts Bay and the response to improvements in effluent quality and offshore transfer of the effluent in September 2000. The monitoring program was designed with limited knowledge of spatial and temporal variability and long-term trends within the system. This led to an extensive spatial and temporal sampling program. The data through 2003 showed high correlation within physical parameters measured (e.g., salinity, dissolved oxygen) and in biological measures such as chlorophyll fluorescence. To address the potential sampling redundancies in the measurement program, an assessment of the impact of reduced levels of monitoring on the ability to make water quality decisions was completed. The optimization was conducted by applying statistical models that took into account whether there was evidence of a seasonal pattern in the data. The optimization used model survey average readings to identify temporal fixed effects, model survey-average-corrected individual station readings to identify spatial fixed effects, corrected the individual station readings for temporal and spatial fixed effects and derived a correlation model for the corrected data, and applied the correlation model to characterize the correlation of annual average readings from reduced monitoring programs with true parameter levels. Reductions in the number of sampling stations were found less detrimental to the quality of the data for annual decision-making than reductions in the number of surveys per year, although there is less of a difference in this regard for dissolved oxygen than there is for chlorophyll. The analysis led to recommendations for a substantially lower monitoring effort with minimal loss of information. The recommendation supported an annual budget savings of approximately $183,000. Most of the savings was from fewer surveys as approximately $21,000 came from the reduction in the number of stations monitored from 21 to 7 and associated laboratory analytical costs.     

江苏省12大湖泊水环境现状与污染控制建议

江苏面积大于50km^2的12个湖泊的水质恶化、面积减少、富营养化、湖泊生态系统退化与湖泊受TP、TN的污染和围湖造田等有关。经济快速发展,第二产业结构偏重,排放污染的总量超过湖泊承载力,湖泊底泥释放N、P及入糊河流携带污染物为造成湖泊环境问题的根本原因。建议调整产业结构,执行严格的排放标准,围绕重点区域、重点行业、重点企业和重点污染源治理,由控制COD为主转为控制COD和N、P并重,引水调控水质,建立湖泊资源数据库和生态系统信息网络,开展湖泊污染物来源分析和富营养化机理研究,开展跨界区域统筹对湖泊综合治理。     

近年胶州湾陆源SGD及其营养盐输送

根据青岛市胶州湾周边的水文地质条件及地下水位、水质动态特征,运用断面法计算了2001～2003年该区地下水及其N、P、Si无机营养盐向海湾的输送量.研究表明近年该区地下水向海湾的输送量分别为(1.87～2.41)×106m3,其中白沙河平原输送量占95%以上.地下水向海湾的NO 2、NH 4、PO3-4输送量较少,而NO 3和可溶性SiO2的输送量较大,分别达(4.3～6.6)×106 mol/a、(0.6～1.1)×106 mol/a,分别占河流输送量的20%和1.3%,白沙河平原地下水NO 3输送量占研究区地下水总输送量的99%.