Diel Variability of Water Quality in a Tropical Polluted Bay

The objective is to describe and quantify the diel variability of water quality in a tropical coastal system, Guanabara Bay, Brazil. Water samples were collected in spring and neap tide cycles over 24 h periods at three strategic sites. A pollution gradient was evident between the sampling sites. The average fecal coliform values decreased from 10⁶ (site 3, most polluted) to 10¹ (site 1, less polluted). Organic matter mineralization was found in a similar gradient to organic pollution. However, complete nitrification was only found associated to regions where the water quality was better. Variability in this data set was determined mostly by the pollution gradient observed, and by tidal influence as well. The poor water quality indicates that the bay undergoes severe environmental stress. However water renewal promoted by tidal action was an important mechanism in diluting the pollution, improving water quality even in ebb tides and in the inner channels. The significance of micro-scale changes in water quality assessment in Guanabara Bay was confirmed, as well as the importance of these strategic sampling sites, reinforcing the importance of these measurements in monitoring programs.     

串叶松香草生物量和营养成分动态及其对土壤理化性质的影响

田间试验和化学分析结果表明,串叶松香草两个品种４个生育期的茎、叶产量均以Ａ型＞Ｂ型,在３ａ内串叶松香草产量随生长年限增加,且以Ａ型品种产量高．串叶松香草３个生育期叶片氨基酸和蛋白质含量高于茎,并以Ａ型品种现蕾期为最高;两个品种氨基酸组分以Ａｓｐ、Ｇｌｕ、Ｌｅｕ和Ｌｙｓ含量高,各生育期氨基酸组分含量变化规律不同．串叶松香草的粗脂肪、Ｃａ、Ｐ和灰分含量以叶＞茎,而粗纤维和可溶性糖含量却以茎中较高．除粗纤维外,其余饲用成分含量均随生育期的出现而呈递降之趋势．串叶松香草现蕾期Ｎ、Ｋ含量和莲座期Ｐ含量达最高．种植３ａ后串叶松香草明显改善土壤物理性质,提高土壤酶活性,明显降低土壤有效Ｎ、Ｐ和Ｋ含量     

基于多项污染物综合相对重要性的主成分子集合环境测点优选法

根据对多项污染物环境测点的优选,提出了单项污染物测值的相对重要性和多项污染物测值的综合相对重要性新概念,并给出了综合相对重要性的计算公式．根据测点的综合相对重要性,再用主成分子集合选择法优选测点该方法与基于交叉相关性的主成分子集合优选法相比,不仅减少了计算量,而且避免了当各单项污染物选出的测点不一致时,难以确定公共优化点的困难．该方法用于成都市大气污染物的12个测点优选结果符合实际情况．     

基于信息相对重要性的主成分法优选环境测点

提出将单项污染物测值反映的信息量表示为相对重要性和将单项污染物的相对重要性综合为多项污染物的综合相对重要性的计算公式。根据测点信息的综合相对重要性,再用主成分子集合选择法优化选点。该方法不仅减少了计算量,也易于确定多项污染物的综合优化点。该方法用于贵阳市大气环境测点优选出的测点能反映该市的环境质量。      

LFG控制利用工程基本参数的试验研究

通过深圳市玉龙坑垃圾填埋场的现场抽气试验。本文进行了填埋气本安全控制与回收利用工程基本参数的研究。     

低渗透石化污染场地多相抽提修复效率的数值模拟

借助TOUGH3/TMVOC软件对华北地区某典型污染场地进行模型概化,模拟再现了挥发性有机化合物(VOCs)在层状低渗透性介质中的运移和分布特征;同时,设置了不同情景的多相抽提方案,分析了渗透率对多相抽提技术(MPE)去除效率的影响.结果表明,VOCs在该介质中主要以非水相液体(NAPL)相形式存在,且NAPL相饱和度...     

基于多种方法的长江上游小流域水质综合评价

选取大河和巴关河流域2018—2022年水质监测数据,运用单因子评价法、Spearman秩相关系数法、综合污染指数法和主成分分析法,对流域水质状况、变化趋势及主要污染物特征进行综合评价分析。结果表明:2018—2022年,大河流域水质未达到地表水Ⅲ类标准;流域整体综合污染指数超过了1,为重污染,下游污染程度较重;营养指标和有机污染物指标存在显著正相关。巴关河流域水质达到了地表水Ⅲ类标准;流域整体综合污染指数未超过1,为中污染,上游污染程度较重;营养指标、有机污染物指标和重金属指标等均呈现出不同程度的相关性。巴关河流域水质总体优于大河流域。TP、NH₃-N、COD_Mn、COD_Cr和BOD₅是影响大河流域和巴关河流域水质的主要因子,均属于有机型及富营养化污染指标,主要来自生活源和农业源。建议选择适宜的评价方法开展系统性小流域污染溯源,分河段有针对性地开展小流域水环境治理。     

摩擦摆隔震支座理论分析与数值模拟研究

介绍了摩擦摆隔震支座的基本构成和隔震原理.利用力学平衡原理,对摩擦摆隔震支座进行了理论分析,推导了摩擦摆隔震支座的刚度和等效粘滞阻尼比,构造了摩擦摆隔震支座的滞回模型,并探讨了该支座的自回复能力,得到了其最大残余位移计算公式.采用有限元软件ABAQUS,对摩擦摆隔震支座进行实体单元建模,模拟低周反复荷载作用下,该支座的...     

Management of process performance at low water temperatures in respect of filamentous organisms

The management of sludge-settling properties in Nordic conditions is of importance during the low temperature (spring) season because of the peak settler load. A survey was made in 10 Finnish waste water treatment plants(WWTP‘ s) and the total extended filament length and DSVI in haft of the plants exceeded the limits, which indicates sludge bulking( 15 km/g SS and 150 ml/g respectively). The dominant organism was Microthrix parvicella, the abundance of which was 59.22% of total extended filament length on average.Chemicals were tested to control the filaments, and it was found that special attention has to be paid to maintaining the nitrification at low temperature. A dosage of(H2O2-besed) oxidants controlled the growth of Microthrix parvicella effectively and rapidly, whereas with the use of aluminium hydroxidechloride a 2 to 5-week period was needed to decrease the filament length.     

釜溪河自贡城区段季节性低氧成因研究

釜溪河为沱江一级支流,在自贡城区段设有国考碳研所断面。收集碳研所断面近10年来水质自动站数据,分析溶解氧(DO)变化特征,采样调查釜溪河自贡城区段水质及河道底泥污染状况,采用相关性分析、数值模拟等,研究分析釜溪河自贡城区段溶解氧分布特征及碳研所断面季节性低氧成因。研究结果表明,碳研所断面的溶解氧质量浓度变化特征呈现春末夏初最低,白天高晚上低的特征。釜溪河碳研所断面河水耗氧类污染物质量浓度较沱江流域内其他断面高,耗氧强度较大,溶解氧质量浓度较沱江流域其他断面偏低;其次,研究河段中釜溪河污水厂以下河段受污水厂低氧水排入和金子凼堰底层低氧水下泄影响,其溶解氧水平整体较污水厂以上河段低;最后,河段底泥有机质含量较高,春夏季气温升高将导致微生物分解活性增强大量消耗溶解氧,同时,闸坝和外来水体排入的水文扰动造成污水厂以下河段水温梯度弱,表层溶解氧易受底层低氧水影响,促使断面形成季节性低氧现象。溶解氧预测模型结果也进一步证实了温度变化和垂向温度梯度弱是碳研所断面溶解氧质量浓度季节性偏低的主要因素。