Sources of Potentially Toxic Elements in Sediments of the Mussulo Lagoon (Angola) and Implications for Human Health

Abstract

The Mussulo lagoon is a coastal environment located near Luanda, one of the SW African cities that has been growing more rapidly during the last decades. Geochemical, mineralogical, and grain-size data obtained for the lagoon sediments are analyzed together, in order to establish the factors that control the distribution of some potentially toxic elements (PTEs). Sediments from northern location tend to be enriched in feldspar and, despite some variability in grain-size distributions, in fine-grained detrital minerals; southern lagoon sediments display very homogenous grain-size distribution and are enriched in minerals associated with salt precipitation (halite and gypsum). Multivariate statistics reveal a close link between some PTEs, namely Co, Hg, Ni, and Pb, for which an anthropogenic source can be postulated. On the other end, As seems to be associated with natural authigenic precipitation in southern lagoon sectors. Sediments enriched in clay also tend to yield more Fe, Mn, Zn, and Cu, but it is unclear whether their sources are natural or anthropogenic. Hazard indexes calculated for children are higher than 1 for As and Co, indicating potential non-carcinogenic risk. For the other elements, and for adults, there is no potential carcinogenic or non-carcinogenic risk.

Preliminary Assessment of Chemical Elements in Sediments and Larvae of Gomphidae (Odonata) from the Blyde River of the Olifants River System, South Africa

“…The proportion of finer particles at S5 was higher than that of coarse grains and may have contributed to the high concentration of chemical elements. Thus, as the grain size decreases, the metal content increases [25,26]. The mean concentration of As was greater than the CCME [27] guideline value of 13 mg kg −1 , dw at all the sites.…”

Groundwater Characteristics and Their Associations with Paleogeomorphological Dynamics in Gantiwarno, Klaten Regency, Central Java Province, Indonesia; A Preliminary

“…Without human influences, natural processes would influence water quality only [6]. Natural factors influence water quality through soil-matrix [5], [9], [11], geological setting and processes [5], [6], [8], [11]- [14], topography [6], type of rock, the local climate [6], [8], natural disasters, climate change [5], [11], hyporheic exchange [5], extent of host-rock and water interaction [12], degree of weathering of bedrock minerals [6], [12], [14], natural leaching of minerals, organic matter and nutrients from soil and aquifer rock [6], [12]; sorting processes [14], atmospheric processes involving evapotranspiration, deposition of dust and salt by wind, hydrological factors leading to runoff, and biological dynamics in the aquatic environment that may change the physical and chemical composition of water [6].…”