Metal binding in soil cores and sediments in the vicinity of a dammed agricultural and industrial watershed

Abstract

The environment is witnessing a downgrade caused by the amelioration of the industrial and agricultural sectors, namely, soil and sediment compartments. For those reasons, a comparative study was done between soil cores and sediments taken from two locations in the Qaraaoun reservoir, Lebanon. The soil cores were partitioned into several layers. Each layer was analyzed for several physicochemical parameters, such as functional groups, particle size distribution, ζ-potential, texture, pH, electric conductivity, total dissolved solids, organic matter, cation exchange capacity, active and total calcareous, available sodium and potassium, and metal content (cadmium, copper, and lead). The metal content of each site was linked to soil composition and characteristics. The two sites showed distinguishable characteristics for features such as organic matter, pH, mineral fraction, calcareous, and metal content. The samples taken toward the south site (Q1), though contain lower organic matter than the other but are more calcareous, showed higher metal content in comparison to the other site (Q2) (average metal content of Q1 > Q2; for Cd 3.8 > 1.8 mg/kg, Cu 28.6 > 21.9 mg/kg, Pb 26.7 > 19 mg/kg). However, the metal content in this study did not correlate as much to the organic matter; rather, it was influenced by the location of the samples with respect to the dam, the reservoir's hydrodynamics, the calcareous nature of the soil, and the variation of the industrial and agricultural influence on each site.

Leaching of Metals in Coastal Technosols Triggered by Saline Solutions and Labile Organic Matter Removal

“…Due to the sensitivity of the XRF gun, and due to the metal enrichment in the samples, only Ca, Fe, Zn and Pb were semi-quantified. For selected layers of the NS and FS technosol cores, acid digestion was done via aqua regia, as described by Kanbar et al (2014). Although aqua regia does not dissolve silicate minerals, it was proven to be a reliable technique for the determination of total metal contents (e.g.…”

“…Indeed, soils that are made of fine grains and contain high organic matter are expected to be more enriched with metals than coarse and OM-poor soils (e.g. (Carrillo-González et al, 2006;Kanbar et al, 2014;Manceau et al, 2002).…”

“…As a result, contaminated and technical soils and sediments have been present since a long time in Lebanon as well as other sites that were famous for trading. Currently, Lebanon contains a lot of industries, especially on the shore; several sites were reported to have signatures of anthropogenic activities, mainly by industrial and agrochemical plants (Ammar et al, 2016(Ammar et al, , 2015Kanbar et al, 2014). Soils, including technosols, located near seas/oceans undergo unique processes; a key parameter that influences metal mobility at those sites is salinity (or ionic strength).…”

Evaluating trivalent chromium (CRIII) toxicity on wild terrestrial plants

“…The bioavailability and uptake of chromium by plants may depend on the characteristics of the metal itself (Rai et al, 1989;Fendorf, 1995) and the physicochemical attributes of the soil, including cationic exchange capacity (Kanbar et al, 2014), presence of natural inorganic oxides (Kotas & Stasicka, 2000), pH ranges (Rai et al, 1989;Palmer & Wittbrodt, 1991), and soil texture Davies et al, 2002;Sharma et al, 2005). Once in the environment, trivalent chromium strongly binds to hydroxide complexes and at acidic pH ranges (usually below 6) becomes mobile and available to living organisms (Kotas & Stasicka, 2000).…”

“…Cationic exchange capacity (CEC) defines the soil's ability to retain positively charged ions and is an important indicator of soil fertility, structure stability and nutrient availability; a higher CEC means that the soil is fertile and more nutrients are available to plants. An organic soil that has a relatively high CEC (up to a 100 meg 100g -1 of soil) diminishes the movement of metals within the growth medium and their further uptake by plants (Kotas & Stasicka, 2000;Kanbar et al, 2014). In artificial soil, the organic matter content and the average measured CEC were 12.16% and 16.8 meg 100g -1 respectively, meaning that chromium could be absorbed by the emerged seedlings.…”