Enrichment and geo-accumulation of heavy metals and risk assessment of sediments of the Kurang Nallah—Feeding tributary of the Rawal Lake Reservoir, Pakistan

Total dissolved and bioavailable elements in water and sediment samples and their accumulation in Oreochromis mossambicus of polluted Manchar Lake.

Assessment of heavy metal concentrations in the food web of lake Beyşehir, Turkey.

Concentrations of heavy metal and radioactivity in surface water and sediment of Hazar Lake (Elazığ, Turkey)

To examine the status and risk of heavy metal pollution in urban lakes, in China, the distribution of several heavy metals (e.g., Cr, Cu, Ni, Pb, Zn) in the sediment of Moshui Lake, Hangyang District, Wuhan City, was characterized. The process of rapid urbanization and industrialization of the district was also studied to find out its relationship with the metal accumulation profile in the sediment. It was found that the total concentration of heavy metals in the sediment was higher than the severe effect level (SEL), at all sampling sites, except those in the riparian zone. The Cr and Cu maximum concentrations were 1,780 and 1,250 mg/kg, approximately 16 and 11 times as much as the SEL values, and they appeared as deep as 32 cm in one sample. The carbonate and exchangeable fractions of Zn were more than 50% of the total Zn content, resulting in very high risk according to the Risk Assessment Code (RAC). For Cu and Ni, a medium RAC value was found for carbonate and exchangeable fractions of 11%-20%. As sensitive indicators of contaminants in aquatic systems, heavy metals in the sediment reflect the outcome of regional urbanization, industrialization, and environmental management. With rapid urbanization, sedimentary Pb and Zn concentrations increased. The experimental results showed that high sedimentary heavy metal concentrations had resulted from rapid urbanization and industrialization, which would absolutely lead to substantial aquatic environmental decline in urban lakes.

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Fraction distribution and risk assessment of heavy metals in sediments of Moshui Lake

Heavy metal concentrations in water and bottom sediments of a Mexican reservoir.

The Lerma is one of the most important rivers of Mexico, where it drains highly populated and industrialized regions. The concentration of six major and trace elements: titanium, manganese, iron, zinc, copper and lead in the surface sediments of the upper course of Lerma river was investigated, in order to identify its distribution along the river and to recognize the principal sites of pollution. The surface sediment samples were collected at 8 sites distributed following the stream flow direction of the river. Major and trace elements concentrations were determined by energy dispersive X-ray spectrometry. The results show that the metal concentrations in the sediments decrease in the sequence: Fe > Ti > Mn > Zn > Cu > Pb. Concentration of Fe, Mn and Ti were significantly higher than the other metals in site 8,200 meters downstream the Alzate Dam. The high concentrations and spatial variations of Zn, Cu and Pb in the middle sites of the upper course of the Lerma River indicate that the river pollution is probably associated with urban and industrial discharges.

Major and trace elements in sediments of the upper course of Lerma river

In this paper, mercury concentration in the soluble, particulate and total fractions of water and in the sediment from the Jose Antonio Alzate Dam in the State of Mexico was evaluated using neutron activation analysis in order to determine the bioavailability and distribution of this metal Sampling was carried out on three separate seasons – cold dry season, hot dry season and rainy season – such that, at least one complete hydrological cycle in the dam was covered Results show that mercury constitutes a significant problem in the dam Concentration in the water column is higher than the maximum acceptable level (10 ng/L) as established by national environment criteria and is present at considerable levels in the bottom sediments (up to 500 µg/kg) In the water, mercury presents a seasonal variation, where the highest concentrations are found during the dry period and the lowest concentrations at the end of the rainy season due to dilution of the metal in water Sediment concentration of mercury shows evidence of self-cleaning mechanisms in the dam in which, principally through processes of sedimentation, part of the metal is removed from the water column, improving the outflow water quality

Distribution of mercury in the water and bottom sediment of the J.A. Alzate Dam, Mexico

In recent years, the massive increase in Sargassum landings on the Mexican Caribbean coast has generated negative environmental repercussions. This study has two main objectives (1) to analyze the macro and micronutrients of Sargassum fluitans and S. natans in order to (2) use them in the local and regional industry as a biofertilizer in the production of ornamental plants. Sargasso samples were collected from floating arrivals in the sea and landfall in the area of three beaches in Cancun, Quintana Roo, Mexico in 2018. The quantification of the elements in the samples was carried out using the method of fundamental parameters. The concentration of the macronutrients Ca, Na, K and Cl was higher than the elements Mg, S, Si and Sr, as well as two orders of magnitude higher than Al and P. Additionally, the trace elements Fe, Mn, Zn, Cu, and Ni were found in both species. It is worth mentioning that most of these elements are essential to complete the life cycle of plants; therefore, S. fluitans and S. natans can be considered as an excellent natural resource and alternative as a soil improver for the cultivation of ornamental plants.

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G. Zarazua-Ortega

Papers

Heavy metal concentrations in water and bottom sediments of a Mexican reservoir.

Major and trace elements in sediments of the upper course of Lerma river

Distribution of mercury in the water and bottom sediment of the J.A. Alzate Dam, Mexico

Macro and microelement analysis of Sargassum fluitans and Sargassum natans arriving in the coastal zone of Cancun, Quintana Roo, Mexico