Monitoring quantity and characteristics of municipal solid waste in Dhaka City

A reliable estimate of the quantity of solid waste generation in the city is very important for proper solid waste planning and management. However, reported estimates of solid waste generation vary widely and lead to questionability. The reported values have been derived on the assumption of demography, standard rate of waste generation by households, density values, number of trucks engaged for waste transportation and monitoring of truck movement at dump sites, etc. This diverse nature of the available data and the question of accuracy necessitate a rigorous study that has tried to document the waste quantity in the recently formulated master plan of Dhaka City. The socio-economic parameters, behavioral characteristics, generation sources, seasonality, and per capita growth rate are considered in estimating the waste quantity along with its future projections. The findings from the estimation of waste quantities state that seasonal differences in the municipal solid waste stream are not substantial. The most seasonably variable material in the municipal solid waste stream is food waste. Residential waste is relatively homogeneous. Although there are some differences in waste generation depending on demographic and other local factors, most households dispose of essentially similar types of wastes. Variation occurs in waste composition dependent upon income levels and category of sources. Variation also occurs based upon the extent of source reduction and recycling opportunities. As opportunities exist to recycle wastes, the recycling facilities might have to grow at a similar pace to the generation of waste. Physical and chemical characteristics of solid waste are important to implement the waste disposal and management plan for the selection of resource and energy recovery potentials. A number of studies have been conducted to determine the composition of wastes including moisture content and calorific value. The data show that the moisture content in city waste is significantly higher and the calorific value is much lower, which determines the viability of composting or anaerobic digestions rather than waste combustion.     

长江武汉段不同粒径沉积物中多环芳烃(PAHs)分布特征

将采自长江武汉段的沉积物湿筛分成5个粒径的组分（>200 μm,200～125 μm,125～63 μm,63～25 μm,<25 μm）,分别测定其中多环芳烃(PAHs)的含量.结果表明,不同粒径沉积物中PAHs组成基本相同,均以3环以上PAHs为主,但是∑PAHs浓度相差很大,范围为26.1～7 135.9　ng/g.其中,>200　μm沉积物中∑PAHs浓度最高,为7 135.9 ng/g;63～25　μm沉积物中∑PAHs浓度最低,为26.1　ng/g.占沉积物38.6%质量分数的<25　μm沉积物富集了沉积物中约75%的∑PAHs.总有机碳是影响PAHs在不同粒径沉积物中分布的主要因素,不同粒径沉积物中PAHs与总有机碳呈显著正相关（p<0.01）.此外,有机质类型、结构也是影响PAHs在不同粒径沉积物中分布的重要因素.     

不同下垫面雨水径流溶解性有机物特性

为明晰不同下垫面雨水径流中溶解性有机物特性差异,采用三维荧光光谱、同步荧光光谱及树脂分级等方法对北京市城市道路、屋面、广场、绿地4种下垫面径流DOM进行分析.分析发现,下垫面类型影响径流DOM浓度、物质组成及化学组分分布;道路、屋面初期径流DOC浓度较高,并随产流时间增加而逐渐降低,而绿地径流DOC浓度随产流时间增加而增加,广场径流DOC浓度则始终保持较低水平;路面交通活动、大气沉降作用等使道路、屋面和广场等硬化下垫面径流DOM主要由类富里酸和类芳香蛋白物质组成,且以疏水性化学组分为主,其中疏水中性和疏水酸性组分占比较高;受土壤冲刷有机质影响,绿地径流DOM除含类富里酸和类芳香蛋白物质外,还含有大量腐殖质和生物源蛋白物质,以亲水性化学组分为主,且主要为亲水中性和亲水酸性组分.     

北运河上覆水DOM分子组成和结构特征

利用高分辨傅里叶变换离子回旋共振质谱技术(FT-ICR-MS)及分析手段综合表征了北运河上覆水中DOM分子组成和结构特征,揭示了DOM分子组成的迁移转化规律,并评估了DOM分子组成的潜在环境影响.结果表明:北运河上覆水DOM分子化合物主要由木质素(63.19%)和蛋白质(12.96%)组成.上覆水中稳定DOM分子公式主要由难降解木质素和不断循环且再生的基本代谢物及分泌物组成,独特DOM分子公式的多样性与人为活动强度有关,优先被转化或降解的相同DOM分子公式主要为携带高化学活性羧基和羟基的木质素和不稳定的脂质、蛋白质和碳水化合物.北运河具有外源废水输入量高的特点,致使上覆水具有大量不稳定DOM化合物,增加了河流富营养化的潜在风险.     

太湖浮游植物种类组成时空变化规律

从2010年的3月到2010年的10月,通过春、夏、秋3个季度的采样,对太湖东部的浮游植物种类组成及其变化进行渊查,发现浮游植物92属279种,太湖东部五个采样点位的浮游植物常见种季节变化明显,而各湖区浮游植物种类绀成空间变化较小。通过对太湖东部浮游植物种类组成的时空变化的规律的初步探索,为预警监测及水环境保护提供技术支持。     

茂兰喀斯特原生林不同地球化学背景下的土壤种子库的初步研究

采用野外取样和盆栽试验观察相结合的方法,对贵州茂兰3个不同岩性地球化学背景下森林的土壤中的种子进行萌发实验研究,结果表明:(1)贵州茂兰喀斯特森林的土壤中贮藏着丰富的种子,种子库储量在187.5-550粒/m2。(2)相对而言,纯灰岩的种子库储量最大,不纯碳酸盐岩的次之,纯白云岩的种子库储量最小;在垂直方向上,种子密度随着土壤深度的增加而减小。(3)土壤种子库中自然萌发的种子物种多样性指数为纯灰岩>纯白云岩>不纯碳酸盐岩。(4)从土壤种子库萌发的种子数量和组成成分方面来看,纯白云岩和不纯碳酸盐岩之间的相似性系数>纯白云岩和纯灰岩之间的相似性系数>纯灰岩和不纯碳酸盐岩之间的相似性系数。     

Parental condition, brood sex ratio and differential young survival: an experimental study in gulls (Larus fuscus)

Empirical evidence is growing that the offspring sex ratio in birds can be biased in relation to the body condition of parents during breeding. The sex ratio bias may come about because (1) the actual production of the two sexes may be skewed and/or (2) there may be a sex bias in early nestling mortality contingent on parental condition. By manipulating parental condition and giving them a control brood to rear, thereby eliminating effects operating via the eggs, we examined the extent to which parental condition influences the post-hatching survival of male and female lesser black-backed gulls, Larus fuscus. We found that the pre-fledging survival of male chicks was strongly reduced in all-male broods reared by parents in poor condition. Pre-fledging survival of female chicks was, however, unaffected by parental condition or brood sex composition. Thus, independently of any production biases, sex differences in nestling mortality alone can bias the offspring sex ratio at fledging in relation to the prevailing rearing conditions. In other studies on gulls we have, however, also shown that females in poor condition at laying preferentially produce female eggs. Clearly a bias in fledging sex ratio can occur within the same species due to a combination of differential production and differential post-laying mortality; the latter can involve a differential effect of poor egg quality on male and female offspring, differential effects of brood sex composition on their survival and a difference in the capacity of parents to rear males and females. All of these processes need to be taken into account in attempting to understand offspring sex ratios. Received: 15 February 2000 / Revised: 7 August 2000 / Accepted: 26 August 2000     

珠海市PM_(2.5)时空分布特征及其成因分析

选取2015年珠海市国控监测站ρ(PM_(2.5))数据,分析PM_(2.5)中有机碳(OC)、元素碳(EC)、水溶性离子组分等化学组成,ρ(PM_(2.5))时空分布特征,以及与气象因素的相互关系。结果表明,2015年珠海市PM_(2.5)年均值为31.0μg/m3,表现出显著的时间分布规律,月均值呈现"V"型趋势,PM_(2.5)中主要化学组分是有机物(OM),占总质量的34.0%,其次是硫酸根(SO2-4),占总质量的26.9%,具有明显的季节分布特征,呈现冬高夏低分布;ρ(PM_(2.5))日变化呈现双峰型分布,其值工作日显著高于非工作日;ρ(PM_(2.5))与平均温度、相对湿度、风速呈现负相关关系,与气压呈现显著正相关关系;珠海市ρ(PM_(2.5))空间分布总体呈现"东高西低,北重南轻"变化趋势,有机物、SO2-4和NH+4空间分布呈现东部高于西部趋势,颗粒物浓度受地形、气候因素和海域环境等影响呈现多样化分布趋势。     

Concentration of heavy metals in various children's herbal tea types and their correlations

This investigation was undertaken to determine the concentrations of cadmium, lead, mercury, zinc, copper and magnesium in six tea types used as children's tea. Six types of tea of different herbal composition used for children's consumption (T1, T2, T3, T4, T5 and T6) were analyzed in three subsequent collections. The analysis of cadmium showed that the concentration was very similar in all types of children's tea, ranging from 0.233 to 0.369 mg/kg. Lead concentrations were in the range of 0.340–1.564 mg/kg without any significant differences. The analysis of mercury detected very low concentration of this metal in all samples (0.002–0.004 mg/kg). In zinc, the values ranged from 36.633 to 71.711 mg/kg, with significant differences (p < 0.001) according to tea type. Copper concentration was 10.089–30.178 mg/kg with the highest value in T4. The concentration of magnesium was significantly higher in tea T1 and T2 (102.311 and 129.422 mg/kg) in comparison with other tea types where the level was 19.811–37.411 mg/kg. The maximum tolerable limit determined by Codex Alimentarius was not exceeded in any sample. In general, correlation analysis detected high positive correlation between cadmium and lead (r = 0.89), cadmium and mercury (r = 0.92) and between lead and mercury (r = 0.77).     

利用体外实验方法评估稻米中镉的生物可给性和健康风险

为了研究稻米中镉(Cd)的生物可给性与稻米理化性质之间的相互关系以及稻米摄入而导致的Cd健康风险,从湖南某些地区采集了16个稻米样品,利用in vitro方法研究了这些稻米中Cd的生物可给性及其人体健康风险。结果表明:在16个样品中,有13个样品的Cd含量超过稻米中Cd的限量标准(0.2 mg·kg-1)。稻米中Cd的溶解态含量及其生物可给性变化较大,胃阶段和肠阶段Cd的溶解态含量范围分别为0.102~1.70 mg·kg-1和0.015~0.249 mg·kg-1,平均值分别为0.698 mg·kg-1和0.103 mg·kg-1,胃阶段和肠阶段Cd的生物可给性的范围分别为56.8%~82.0%和6.62%~15.9%,平均值分别为70.9%和11.1%。模拟肠液中Cd的溶解态含量与稻米的纤维含量之间有显著的相关性。如果不考虑稻米中Cd的生物可给性,所采集的所有稻米样品的摄入都将导致成人和儿童健康风险。如果我们考虑了稻米中的生物可给性,只有31%的稻米样品会对成人产生健康风险,将有50%的稻米样品会对儿童产生健康风险。