Temporal and spatial distribution of trace metals in the Rufiji delta mangrove, Tanzania

Abstract

Spatial and temporal distribution of trace metals and their cycling is a key issue for understanding the ongoing biogeochemical processes in coastal environments. Sediment cores were collected from six different sampling locations from the Rufiji delta mangrove forests in southeastern coastal Tanzania that are perceived to be impacted by urban development and agricultural activities in the catchment, and pollution in upstream sections of the Rufiji River. The chronology and sediment accumulation rates at these sampling sites were derived based on the distribution of 210Pbexcess method. The trace metals (As, Cd, Cr, Cu, Ni, Pb, and Zn) were sequentially extracted as per the BCR method and analyzed. The results indicate that the mass accumulation rates range from 0.40 g cm−2 year−1 (cores NR3 and NR4) to 1.75 g cm−2 year−1 (core SR1). Trace metals in the cores are mainly associated with the residual phase and their abundances in sediments are ranked as Cr > Zn > Ni > Cu > Pb > Cd. The results imply that trace metals in the Rufiji delta mangroves are mainly of crustal origin, and they are less sensitive to weathering. Further, these metals are least available for uptake by plants and they pose limited threat to the biota.

Spatial variation of nutrients and primary productivity in the Rufiji Delta mangroves, Tanzania

“…Field surveys and subsequent modelling captured the spatial and temporal distribution of nutrients and future productivity trends in the Rufiji Delta. These investigations complement recent studies on the distribution of trace metals in the Rufiji sediments (Minu et al 2018) and the accumulation of contaminants in a telescoping food-chain in estuarine waters (Shilla and Routh 2017;Shilla et al 2019). The new information generated will help in the management of natural resources in terms of land-use practices, productivity changes in aquatic bodies, pollution and urban development in the catchment.…”

Assessment of the quality and quantity of organic matter in the Rufiji mangrove surface sediments using biochemical composition

“…Mangrove forests support an extensive food web through their large production of detritus, which is broken down by fungi and bacteria. Several omnivorous crustaceans of commercial importance spend part of their life cycles in mangroves feeding on the detritus, live benthic microalgae, occasional animal materials, and fine inorganic particles (Minu et al 2018).…”

Water, Soil and Air Pollutants’ Interaction on Mangrove Ecosystem and Corresponding Artificial Intelligence Techniques Used in Decision Support Systems - A Review

“…Major heavy metal pollutants found in the mangrove ecosystem are Cadmium (Cd), Chromium (Cr), Copper (Cu), Zinc (Zn), Lead (Pb), Nickel (Ni), Manganese (Mn), Mercury (Hg), Arsenic (As), Cobalt (Co) and Iron (Fe) [34,35,[37][38][39][40][41][42][43][44]. The pollution sources of trace metals are due to anthropogenic inputs such as metal processing, domestic sewage, agricultural and industrial activities [34,37,39,43,45].…”