Mercury contamination in fish from gold mining areas in Indonesia and human health risk assessment

This study investigates the effects on fish and assesses human health hazards from mercury released in two gold mining areas in Indonesia: Tatelu (North Sulawesi Province) and Galangan (Katingan District, Central Kalimatan Province). In Tatelu, 154 fish specimens of 10 freshwater species were collected, as well as five marine species from the fish market. The mean concentration of total mercury in muscles of freshwater fish from this area was 0.58+/-0.44 microg/g, with more than 45% of fish having Hg levels above the WHO guideline for human consumption of 0.5 microg/g. In Galangan, where 263 fish specimens of 25 species were collected, the total mercury in muscles averaged 0.25+/-0.69 microg/g. Excluding data from flooded open pits in sub-area P4, mean Hg levels in fish from Galangan were 2 to 4 times lower than 0.5 microg/g, while fewer than 10% of fish from Galangan exceeded WHO guidelines. The Hazard Quotient (HQ) was applied to both areas to determine the threat of MeHg exposure for communities in both areas. The HQ is a risk assessment indicator which defines the ratio of exposure level to a single substance in relation to a reference dose. Samples from Tatelu (excluding marine species) had an HQ above one, while those from Galangan resulted in values of 2.4 for the whole area and 9.9 for sub-area P4, pointing to potentially harmful fish consumption for the local population. By using the single-compartment model to estimate mercury levels in blood and hair from daily intake dose, sub-area P4 showed the highest levels, higher than the upper limit guideline for pregnant women, but still lower than threshold levels associated with observed clinical effects.     

Synthesis of ettringite: a way to deal with the acid wastewaters of aluminium anodising industry

Synthesis of ettringite from acid wastewaters of the aluminium anodising industry has been studied as a possible route of reducing the emissions to the environment, recovering at the same time resource materials as a useful marketable mineral. Wastewaters of different concentrations have been subjected to the process of synthesis suspending calcium oxide and calcium aluminate powders at different time and pH conditions. High caustic alkalinity (pH approximately 12) and low sulphate concentrations (<0.1 M) are the most suitable conditions to synthesise ettringite. The mineral characterisation has been performed using X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA) and differential thermal analysis (DTA), proving the high purity of the pursued solid product when hydrated in the appropriate sodium hydroxide concentrations. In such conditions, around 90% of the aluminium initially present in the wastewater solutions is recovered in the form of ettringite.     

Fluid filling of a membrane tube with self-weight

The filling of a membrane tube with self-weight by a fluid is studied theoretically for the first time. The fundamental problem depends on two non-dimensional parameters, $\beta$ and $\gamma$ which represent the importance of internal pressure and membrane self-weight respectively. The nonlinear equations are solved by an efficient numerical integration method. It is found that membrane self-weight has considerable effect on the tube geometry and the tension of the membrane at low filling pressures.     

Observations on the changes in nitrate concentrations along streams in seven upland moorland catchments in Northeast Scotland

River water has been sampled under baseflow conditions in both summer and winter at c. 250-m intervals along the length of each of seven rivers in northeast Scotland, and the nitrate contents have been determined. The resultant data have been examined in the context of the nitrogen saturation hypothesis. Capacity of the catchment soils to retain nitrate was generally minimal in winter. Although biological uptake of nitrate was evident in summer, in the upper part of each catchment substantial nitrate leaching still occurred. The phenomenon was most marked in water draining from hill peats, except where these were conspicuously waterlogged. The results are discussed in the context of possible nitrogen saturation effects on upper catchment slopes.     

让水泥窑成为市政设施的重要一环

在中国建筑材料联合会换届大会上,联合会面向全行业提出了"宜业尚品、造福人类"的发展新目标。这一目标的提出,符合党的十九届五中全会精神的要求,契合了国家远景目标,是国家发展目标在建材行业的具象化和具体体现,富有新意且意义深远。水泥生产是以石灰石、黏土等为原料,煤炭作为燃料煅烧并添加其他混合材而成的一种胶凝材料。第一次产业革命,催生了硅酸盐水泥的问世。     

Oxygen consumption and activity of the white sucker (Catostomus commersoni), in lethal and nonlethal levels of the organochlorine insecticide, methoxychlor

The survival, oxygen consumption and spontaneous activity of suckers were determined at 15°C in water containing different concentrations of methoxychlor in ethanol, ethanol, and no added substances. A dynamic bioassay was used to estimate the 96 h LC50, which was found to be 0·0345 ppm. Routine oxygen consumption was determined in a continuous-flow respirometer, and the activity was recorded in separate experiments by measuring the water disturbance using silver wire electrodes.After 24 h fish exposed to untreated, ethanol-treated and 0.01 ppm methoxychlor-treated water had oxygen uptake rates which were relatively constant and near standard levels. At 0.10 ppm methoxychlor (lethal to all fish within 85 h), oxygen consumption rates were 2–3.5 × as high as those of control fish. Activity also greatly increased. The fish lost their balance along with the coordination between opercular and locomotor movements. Suckers that died in 0.04 ppm methoxychlor showed oxygen uptake rates and poisoning symptoms similar to 0.10 ppm treated fish, while those that survived this treatment had rates similar to control fish. The increase in ventilation which accompanies this hyperactivity may result in increased uptake of insecticide and thereby explain the irreversible nature of the response.     

Mesure en place de la permeabilite des sols fins

Bulletin of Engineering Geology and the Environment - La mesure en place de la perméabilité k des sols fins est un moyen d'améliorer la prévision des vitesses de tassement...     

如何发挥建设单位在安全生产管理中的作用

在国家基础建设过程中,工程质量、进度、成本控制三大目标的实现是建立在安全生产的基础之上的,脱离了安全生产特别是防火、防触电、防高空坠落、防土方坍塌等安全措施的保障,就不能充分保证三大目标的实现。一般情况下,施工安全生产管理工作由承建商负责,建设单位不必直接参与安全生产管理工作,但在实际管理中,一旦建设单位积极参与建设工程安全生产管理工作,必将对进一步促进工程质量、进度、成本三大控制目标的实现产生重要的推动作用。下面,我就建设单位如何做好建设工程安全生产管理工作谈一下个人看法。1在招标文件中规定统一的安全生…     

住宅日照中一个容易忽视的问题-阳台遮阳的分析

现在的住宅设计越来越强调人居健康，日照采光问题也越来越得到重视。本文通过实例分析了大阳台对下层居室的遮阳影响。     

河南建业Giant Mall

河南建业Giant Mall是河南省建设规模较大的综合性开发项目之一，总占地面积约5hm^2，它包括购物广场，商业写字楼及高级公寓。该项目落成后将成为当地档次最高、规模最大的商业零售中心，也是引领时尚潮流的娱乐休闲中心。