Environmental pollution impact on water and sediments of Kumaun lakes, Lesser Himalaya, India: a comparative study

A study of the water and sediment chemistry of the Nainital, Bhimtal, Naukuchiyatal and Sattal Lakes of Kumaun, has shown that the water of these lakes are alkaline and that electrical conductivity, total dissolved solid and bicarbonate HCO ₃ ⁻ are much higher in Nainital than in the other three lakes. The weathering of limestone lithology and anthropogenic pollution, the latter due to the very high density of population in the Nainital valley, are the primary sources of enhanced parameters. The low pH of Nainital Lake water is due to low photosynthesis and enhanced respiration, increasing CO₂ in the water and the consequent enhancement of Ca²⁺ and HCO ₃ ⁻ . The dissolved oxygen in Nainital Lake is less compared to other lakes, indicating anoxic conditions developing at the mud–water interface at depth. The PO ₄ ³⁻ content in Nainital is higher (124 μg/l), showing an increasing trend over time leading to eutrophic conditions. The trace metals (Cu, Co, Zn, Ni, Mn, and Sr) are present in greater amounts in the water of Nainital Lake than in the other three lakes, though Fe and Cr are high in Bhimtal and Fe in Naukuchiyatal. The higher abundance is derived from the leaching of Fe–Mg from metavolcanic and metabasic rocks. Most of the heavy metals (Cr, Ni, Cu, Mn, Fe, Sr, and Zn) significantly enrich the suspended sediments of the lakes compared to the bed sediments which due to their adsorption on finer particles and owing to multiple hydroxide coating and organic content, except for Fe, which is enriched in the bed sediments. The high rate of sedimentation, 11.5 mm/year in Nainital, compared to Bhimtal with 4.70 mm/year, Naukuchiyatal with 3.72 mm/year, and Sattal with 2.99 mm/year, has resulted in shorter residence time, poor sorting of grains, and lesser adsorption of heavy metals, leading consequently, their depletion in the bed sediments of Nainital Lake.     

Water pollution in gold mining industry: a case study in Roşia Montană district, Romania

The preliminary study of streams and rivers from the Roşia Montană area revealed that the concntration of heavy metals— Cd, Mn, Cu, Pb, and Zn—are above accepted limits. The gold extraction method is based on flotation. The most important pollution sources are mine tailings. The determinations were performed for samples collected in: April 2004, July 2004, September 2004, November 2004, February 2005 and May 2005. The highest concentrations were found for cadmium in September 2004: 0.17 mg/L; for copper in September 2004: 1.38 mg/L; for manganese in July 2004: 239.4 mg/L; for lead in May 2005: 0.54 mg/L; and for zinc in September 2004: 35.37 mg/L;. This study involved three small rivers (streams) that flow into the Mureş River and finally into the Danube River, having a great impact on human health and environmental stability in the area. In May 2005, a sample of drinking water from the mining district was also collected.     

Present environment and historic changes from the record of lake sediments, Dhaka City, Bangladesh

Changes in the urban environment of Dhaka City have been evaluated from the geochemical compositions of bottom sediments from two lakes, Gulshan-1 and –2. Abundances of Pb, Zn, Fe₂O₃ and total sulfur in a Gulshan-1 core gradually increase toward the sediment–water interface. Three stages of condition change can be recognized in Gulshan-1, based on trace metal concentration patterns. The basal Stage I corresponds to background Dhaka sedimentation, whereas gradual increase in Stage II represents the beginning of pollution. Marked increases in Pb and Zn in Stage III reflect rapid urban development and increased emissions to the atmosphere. The condition of the Dhaka environment is compared to that of Japan based on Zn–Fe₂O₃ and Pb–Fe₂O₃ relations. Zn–Fe₂O₃ ratios in Stage I Dhaka sediments are similar to normal Japanese sediments, whereas Stage II data lie on the same trend as Japan urban sediments. Dhaka Stage III samples have greater Zn:Fe₂O₃ ratios than Japanese urban sediments, suggesting Zn pollution from poorly-controlled industrial sources. In contrast, the Dhaka Pb–Fe₂O₃ trend lies between normal and urban Japanese sediments. Although vehicle emissions in Dhaka are now significant, the data suggest that Pb pollution from this source remains in its early stages.     

松花江上游地区汞污染的化学生态效应

采样分析了吉林省东部松花江上游金矿开采区及其附近水、土壤、动植物及河流沉积物样品中汞的含量，发现河流沉积物中汞的污染相当严重；受其影响当地的植物和两栖类动物——中国林蛙体内总汞和甲基汞含量也明显高于对照组。实验表明，林蛙内脏对汞的富集能力大于肌肉；秋季对汞的富集大于春季；河流沉积物中甲基汞的含量与林蛙体内甲基汞的含量有较好的正相关。汞污染的来源与区域内个体金矿的滥采滥排有直接关系，表明人类活动所产生的有毒重金属在地表过程中出现了化学生态效应。     

Chemical effects of a near-to-nature detention pond on a small urban headwater

The near-to-nature approach has been established as best practice for stormwater management. However, pollutant mobility within such systems and its impact on small receiving waters are partly unexplained. The study takes place in an urbanised headwater catchment in south-western Germany with an area of 0.4 km². Runoff from roofs, roads, parking lots and gardens is collected in wells or trenches and stored in private and public dry detention basins. Accordingly, this study investigates pollutant input to a detention pond, removal efficiency and the associated effects on the receiving water.Grab samples with high temporal resolution of the receiving water (16 flood events with 315 samples and 41 baseflow samples), the three inflows of the detention basin and its outflow (four flood events with 64 samples) were taken. The outflow of the dry pond is recovered in the hydro- and chemographs of the receiving water. Runoff from roads with increased traffic volume caused the highest PAH inputs and runoff from the residential area showed the highest zinc concentrations, which partly infringe European Environmental Quality Standards. Yearly pollutant inputs (DOC, TSS, PAH, nutrients, metals) from the settlement into the tributary are reduced in the detention pond by up to 80%.     

Development of a soil moisture‐based distributed hydrologic model for determining hydrologically based critical source areas

A simple grid cell‐based distributed hydrologic model was developed to provide spatial information on hydrologic components for determining hydrologically based critical source areas. The model represents the critical process (soil moisture variation) to run‐off generation accounting for both local and global water balance. In this way, it simulates both infiltration excess run‐off and saturation excess run‐off. The model was tested by multisite and multivariable evaluation on the 50‐km² Little River Experimental Watershed I in Georgia, U.S. and 2 smaller nested subwatersheds. Water balance, hydrograph, and soil moisture were simulated and compared to observed data. For streamflow calibration, the daily Nash‐Sutcliffe coefficient was 0.78 at the watershed outlet and 0.56 and 0.75 at the 2 nested subwatersheds. For the validation period, the Nash‐Sutcliffe coefficients were 0.79 at the watershed outlet and 0.85 and 0.83 at the 2 subwatersheds. The per cent bias was less than 15% for all sites. For soil moisture, the model also predicted the rising and declining trends at 4 of the 5 measurement sites. The spatial distribution of surface run‐off simulated by the model was mainly controlled by local characteristics (precipitation, soil properties, and land cover) on dry days and by global watershed characteristics (relative position within the watershed and hydrologic connectivity) on wet days when saturation excess run‐off was simulated. The spatial details of run‐off generation and travel time along flow paths provided by the model are helpful for watershed managers to further identify critical source areas of non‐point source pollution and develop best management practices.     

Likely effects of climate change on groundwater availability in a Mediterranean region of Southeastern Spain

Groundwater resources are typically the main fresh water source in arid and semi‐arid regions. Natural recharge of aquifers is mainly based on precipitation; however, only heavy precipitation events (HPEs) are expected to produce appreciable aquifer recharge in these environments. In this work, we used daily precipitation and monthly water level time series from different locations over a Mediterranean region of Southeastern Spain to identify the critical threshold value to define HPEs that lead to appreciable aquifer recharge in this region. Wavelet and trend analyses were used to study the changes in the temporal distribution of the chosen HPEs (≥20 mm day^?1) over the observed period 1953–2012 and its projected evolution by using 18 downscaled climate projections over the projected period 2040–2099. The used precipitation time series were grouped in 10 clusters according to similarities between them assessed by using Pearson correlations. Results showed that the critical HPE threshold for the study area is 20 mm day^?1. Wavelet analysis showed that observed significant seasonal and annual peaks in global wavelet spectrum in the first sub‐period (1953–1982) are no longer significant in the second sub‐period (1983–2012) in the major part of the ten clusters. This change is because of the reduction of the mean HPEs number, which showed a negative trend over the observed period in nine clusters and was significant in five of them. However, the mean size of HPEs showed a positive trend in six clusters. A similar tendency of change is expected over the projected period. The expected reduction of the mean HPEs number is two times higher under the high climate scenario (RCP8.5) than under the moderate scenario (RCP4.5). The mean size of these events is expected to increase under the two scenarios. The groundwater availability will be affected by the reduction of HPE number which will increase the length of no aquifer recharge periods (NARP) accentuating the groundwater drought in the region. Copyright © 2016 John Wiley & Sons, Ltd.     

The Fluxes and Behaviour of Plumes Inferred from Measurements of Coherent Structures within Images of the Bulk Flow

This paper describes how measurements of the movement of identifiable features at the edge of a turbulent plume can be interpreted to determine the properties of the mean flow and consequently, using plume theory, can be used to make estimates of the fluxes of volume (mass), momentum, and buoyancy in a plume. This means that video recordings of smoke rising from a chimney or buoyant material from a source on the sea bed can be used to make accurate estimates of the source conditions for the plume. At best we can estimate the volume flux and buoyancy flux to within about 5% and 15% of the actual values, respectively. Although this is restricted to the case of a plume rising in a stationary and unstratified environment, we show that the results may be of practical use in other more complex situations. In addition, we demonstrate that large-scale (turbulent) coherent structures at the plume edge form on a scale approximately 40% of the local (mean) plume half-width and travel at almost 60% of the average local (mean) velocity in the plume.     

固体聚合膜电解浓集法测量天然水中低含量氚的化学淬灭效应研究

固体聚合膜电解浓集法是浓缩氚含量较低(1 Bq/m~3)的天然水样的常用方法,但因水样自身含有杂质离子或电解装置聚合膜带入杂质进入浓集液,使浓集液偏酸性,在测量过程中易产生化学淬灭效应,导致氚的测量值偏低。本文研究了水样自身存在的杂质离子和聚合膜上残留的杂质离子、样品溶液的pH值及其电导率所产生的化学淬灭效应的影响,实验表明,为减少化学淬灭效应,提高测量低含量氚的准确性,需保证水样溶液呈中性,电导率≤1μS/cm,同时避免杂质沉积在聚合膜上。如果水样溶液的pH值偏酸性、电导率大于1μS/cm,可采用酸碱混合型离子交换树脂去除水样中自身的杂质;对于聚合膜引入的杂质,可在电解后的水样中加入微量氨水将其pH值调节至中性。     

我国尾矿综合利用研究现状及建议

尾矿资源综合利用问题已受到世界各国的重视,其对策已由消极的废物处理转向物质再回收,尾矿资源化的发展趋势越来越清晰。但是,我国尾矿综合利用率和发达国家相比还存在较大的差距。大量的尾矿积存,对矿山周边地区环境、土地利用造成了严重的影响。开展典型尾矿资源综合利用技术研究和推广尾矿资源产业化利用技术研究与推广,不但可使原来资源枯竭或资源不足的矿山焕发青春,而且还能够重新成为新的资源基地,以开辟新的材料科技领域,推动科技进步,同时也可以解决环境污染、改善生态环境和整治国土,具有巨大社会、经济和环境效益。因此尾矿的综合利用要做到国家重視、立法保障、评价先行、技术支撑、全部利用,才能真正解决尾矿污染等问题。