Underground Sediments Research Articles

Assessment of a low-enthalpy geothermal resource and evaluation of the natural CO2 output in the Tor di Quinto area (Rome city, Italy)

Rome Capital City is located in a high heat flux area of central Italy, suitable for low-enthalpy geothermal exploitation. In the central-northern part of the city, near Tor di Quinto hippodrome close to Tiber River, a wide undeveloped area occurs, which is a possible future urban development site. We present the results of a geochemical and geophysical study aimed at assessing the presence in this zone of a low-enthalpy geothermal aquifer and at evaluating its depth, thickness and the physico-chemical characteristics of the geothermal water. Furthermore the natural CO2 output of this zone has been investigated. A soil CO2 flux survey with 551 measurements over a surface of 3.09 km2 revealed the presence of parallel NW-SE trending positive flux anomalies. The total CO2 output was estimated to 87.77 t*day−1, most of which (85%) of endogenous or mixed origin. An Electrical Resistivity Tomography survey, consisting of five parallel 355 m long and 100 m spaced profiles, allowed the reconstruction of the stratigraphy of the underground sediments, which are fluvial deposits of the near Tiber River. The geothermal water is hosted in a low-resistivity layer, corresponding to the Tiber base gravels, which are here 20 m thick and whose top is 40 m below the surface. The water has a nearly constant temperature of 17.5 °C, a relatively high salinity and an appreciable content in dissolved gas. This low-enthalpy resource is suitable for direct uses, e.g. individual and district heating/cooling, sanitary hot water, spa facilities for swimming and bathing.

Distribution of antibiotics in alluvial sediment near animal breeding areas at the Jianghan Plain, Central China

Antibiotics are increasingly detected in groundwater, but little is known about their presence in deep underground sediments. In this study, underground sediment samples were collected from pig farms, chicken houses, fishponds and riverbanks in a small region of the Jianghan Plain. Sixteen antibiotics were detected in different layers of sediments in various animal-breeding areas, with the riverbank containing the most pollution, followed by the fishpond, then the pig farm and the least being the chicken house. Samples taken from different sections of the collection sites and tested for each antibiotic compound revealed significant pollution, with the riverbank containing the most pollution, followed by the fishpond, then the pig farm and the least being the chicken house. The concentrations of the targets did not decrease with depth, but increased between 0.6 m and 1.0 m, which was a significant fluctuation. The aquifer sediment analysis indicated that the greatest antibiotic retention was within 8 m, with a small increase between 12 and 16 m, consistent with the depth of sandy aquifer layers. None of the compounds were detected in the deep layer at 20 m but for sulfadiazine and chlorotetracycline. Tetracyclines and Fluoroquinolones were the two groups observed at higher concentrations in most sediment layers, although their residual levels no more than 20 ng g−1. This study revealed that antibiotics generally exist in the underground environment, along with groundwater migration and particle adsorption. The pollution of antibiotics in alluvial sediments is an immense challenge to groundwater remediation, and its environmental effects should be studied.

ANALYTICAL STUDY FOR HEAVY METALS POLLUTION IN SURFACE WATER AND SEDIMENT FOR SELECTED RIVERS OF BASRAH GOVERNORATE

Concentration of 2 heavy metals; lead and mercury (Pb and Hg) in rivers and sediments soil were studied at different sites in Basrah. In this study, the effect of lead and mercury pollutions is studied together with determining their locations in the surface water and sediments at some areas in the South of Iraq (Basrah Governorate) particularly in the upper areas of the Arabian Gulf and in its northern part. These seven locations are: Qurnah, Madinah, Deir, Ashar, Abo Al–Khasib, Zubair and Um Qasir. The effect of the lead and mercury concentration on surface water and sediments analysed during 2014-2015 quarterly. Standardized method have been followed in analysing and comparison the surface water standards and sediment soil just to determine the percentage of lead and mercury pollution and assesse the values with standard pollution index. Overall concentrations of Pb in the rivers ranged from 0.44-4.5 mg/l for surface water and soil sediment samples ranged from 0.0-7.36 mg/kg, and for Hg in the rivers from 0.0003-0.006 mg/l and soil sediment samples ranged from 0.0005-0.009 mg/kg. The concentration of heavy metals in the surface water and soil display the following decreasing trend: Pb>Hg. From this result, found that levels of heavy metal in surface water and soil near industrial areas give higher value compared with other locations in Basrah. The Pollution index revealed that Pb and Hg give low contamination. The highest concentrations values are recorded in Abo Al-Khasib (7.63 ppm) for the underground sediments, the lowest concentrations values are recorded in Madina for the depth sediments. The highest concentrations are recorded in Al-Deer (0.009 ppm) for the mercury pollution. Results of combined heavy metal concentration and heavy metal assessment indicate that industrial activities and traffic emission represent most important sources for Hg and Pb. The pollution Index were calculated for the two pollutants concentrations at the rivers and soils.

東北地方南部，郡山盆地地下における更新世テフラ層序と堆積物

東北地方南部，郡山盆地地下における更新世テフラ層序と堆積物

福島県，会津盆地中西部地下における第四紀後期テフラの層序

福島県，会津盆地中西部地下における第四紀後期テフラの層序

Hexachloro benzene in the Nanshan Karst systems, China

Karst areas have much higher ecological vulnerability and are easy to be contaminated with hexachlorinated benzene (HCB) which is introduced as health risk pollutants. HCB concentrations were used to understand the transport of HCB conducted in the Nanshan karst system, China. Water, sediments from the underground river and water, sediments and soil from the surface systems were collected monthly in 2011 - 2012 and HCB were analyzed. The levels of HCB were 19.9 ng L-1 in underground waters and 11.6 ng g-1 in underground sediments while 99.1 ng L-1 in surface waters and 110.5 ng g-1 in surface sediments and 2.8 ng g-1 in soils. Seasonal variations were found in concentrations of HCB both in the waters and the sediments. HCB concentrations varied from 7.8 ng L-1 in winter to 86.9 ng L-1 in spring in the groundwaters and 0.3 ng g-1 in autumn to 36.7 ng g-1 in spring in the underground sediments. HCB concentrations varied from 38.6 ng L-1 in autumn to 1019.8 ng L-1 in spring in the surface waters, 0.7 ng g-1 in autumn to 133.4 ng g-1 in spring in the surface sediments and 2.5 ng g-1 in autumn to 17.4 ng g-1 in winter in soil. The substantial seasonal variation found between underground system and surface system which indicate that the surface systems play major role for the transport and contamination of HCB in the underground river systems due to karst features.Bangladesh J. Sci. Ind. Res. 50(2), 109-116, 2015

Sources and transports of organochlorine pesticides in the Nanshan underground river, China

Karst areas have much higher ecological vulnerability and are prone to be contaminated. Organochlorine pesticides (OCPs) were detected in waters and sediment from the two sites of the karst Nanshan underground river system, China, to understand the sources and transport of OCPs in the underground river systems. Obviously, seasonal variations were found both in the waters and the sediments. Detected OCPs ranged from 61 to 936 ng L−1 in the groundwaters and 51–3,842.0 ng g−1 in the underground sediments, respectively. OCPs in groundwaters were mixture of younger and older residues from commercial sources. The maximum OCPs in the sediments of the underground river were historically older residues from commercial sources. The sources of OCPs in the waters and sediments of the underground river indicated that the surface systems play an important role in OCPs transport and pollution in the underground river. Karst features were liable for the transport behavior.

Polychlorinated biphenyls in the Nanshan Underground River, China

Karst areas have much higher ecological vulnerability and are easy to be contaminated by polychlorinated biphenyls (PCBs) which are introduced as health risk pollutants. PCBs concentrations were used to understand the transport behavior of PCBs conducted in the karst Nanshan Underground River, China. Water and sediments from the underground river water, and sediments and soil from the surface of the corresponding watershed were collected monthly in 2011 and 2012 and PCBs were analyzed. Seasonal variations were found in concentrations of PCBs both in the waters and sediments. PCBs concentrations varied from 0.3 to 29.9 ng·L−1 in the groundwater, while from 0.1 to 366.1 ng·g−1 in the underground sediments. Correlations were found in concentrations of PCBs in waters and sediments between the underground river and surface systems which indicate that the surface systems play a major role for the transport of PCBs and contamination in the underground river systems. Karst features are liable for the transport behavior. The underground river waters transport PCBs at mean 3 g·day−1.

Hydrogeochemical evolution of confined groundwater in northeastern Osaka Basin, Japan: estimation of confined groundwater flux based on a cation exchange mass balance method

A confined aquifer system has developed in argillaceous marine and freshwater sediments of Pliocene–Holocene age in the northeastern Osaka Basin (NEOB) in central Japan. The shallow groundwater (<100 m) in the system is recharged in a northern hilly to mountainous area with dominantly Ca-HCO 3 type water, which changes as it flows toward the SW to Mg-HCO 3 type and then to Na-HCO 3 type water. Comparison of the chemical and Sr isotopic compositions of the groundwater with those of the bulk and exchangeable components of the underground sediments indicates that elements leached from the sediments contribute negligibly to the NEOB aquifer system. Moreover, model calculations show that contributions of paleo-seawater in the deep horizon and of river water at the surface are not major factors of chemical change of the groundwater. Instead, the zonal pattern of the HCO 3-dominant groundwater is caused by the loss of Ca 2+ from the water as it is exchanged for Mg 2+ in clays, followed by loss of Mg + Ca as they are exchanged for Na + K in clays between the Ca-HCO 3 type recharge water and the exchangeable cations in the clay layers, which were initially enriched in Na +. Part of this process was reproduced in a chromatographic experiment in which Na type water with high 87Sr/ 86Sr was obtained from Mg type water with low 87Sr/ 86Sr by passing it through marine clay packed in a column. The flux of recharge water into the confined aquifer system according to this chromatographic model is estimated to be 0.99 mm/day, which is compatible with the average recharge flux to unconfined groundwater in Japan (1 mm/day).

Underground sediments in a fluorite vein at Maine (Cordesse, 71-France)

Underground sediments in a fluorite vein at Maine (Cordesse, 71-France)