Spatial and seasonal mercury distribution in the Ayapel Marsh, Mojana region, Colombia

Abstract

Geographical and temporal changes of total mercury (T-Hg) concentrations in sediments, macrophytes and fish were evaluated in the Ayapel Marsh, Mojana, Colombia. Sampling was conducted during 2006-2007, including both rainy and dry seasons, and T-Hg was measured using atomic absorption spectroscopy. Distribution of T-Hg in sediments and the macrophyte Eichhornia crassipes showed that higher concentrations were found along the flooding pathway of the Cauca River. Hg has also polluted the food chain. Highest T-Hg concentrations in fish were detected for the carnivorous Pseudoplatystoma fasciatun (0.432 ± 0.107 μg/g, fresh weight [fw]), and lowest in the non-carnivorous Prochilodus magdalenae (0.143 ± 0.053 μg/g, fw), with differences between trophic levels. T-Hg for fish samples (0.298 ± 0.148 μg/g, fw) did not exceed the limit consumption level (0.50 μg/g, fw). It is concluded that mercury-polluted sediments from the Cauca River, contribute to Hg deposition into the Ayapel Marsh. Accordingly, interventions must be conducted to decrease Hg accumulation in fish.

Effects of macrophytes on the fate of mercury in aquatic systems

“…The largest differences were reported in Ipomoea aquatica with 48‐fold to 72‐fold and 1700‐fold increases in concentration of roots versus shoots for THg and MeHg, respectively (Table ) . However, studies concerning E. crassipes report roots:shoots concentration ratios of 0.95, 1.6, 1.8, 8.0, and 9.8 , illustrating the difficulty in generalizing and comparing the different experimental settings and perhaps ecotypes.…”

“…Macrophytes can accumulate Hg in shoots directly from the water column. The accumulation of Hg in shoots of macrophytes has been reported in the laboratory using Hg spikes , and in the field . Data concerning accumulation and calculated BAF, the ratio between the concentrations in shoots of macrophytes and the initial concentration in water or media, are summarized in Table .…”

Passive Samplers Deployment in the Ayapel Swamp for Monitoring Temporal Dynamics of Mercury in the Water Column

“…Therefore, several studies have been made in this site. It has been found mercury in plants, fishes, jaguar teeth and human hair [9]. This situation poses a threat to human health because the Swamp serves as a source of drinking water and fishery products.…”

Flood‐induced metal contamination in the topsoil of floodplain agricultural soils: A case‐study in Colombia

“…The socio‐economic and ecological implications of these climatic events in La Mojana floodplain are worrisome, as half of the maize and rice production is lost during drought and maize production is entirely lost during flood events. Moreover, floods caused by the overflowing of the rivers, which collect wastes containing toxic metals from surrounding mining areas, have led to crop losses and severe pollution (Marrugo, Benítez, Olivero, Lans, & Vazquez, ; Marrugo‐Negrete, Olivero Verbel, Lans Ceballos, & Norberto Benitez, ; Marrugo‐Negrete, Pinedo‐Hernández, & Díez, ; OCHA, ; Pinedo‐Hernández, Marrugo‐Negrete, & Díez, ). At present, the dry season lasts longer, and the rains are torrential, causing floods that can occasionally be severe, as in the 2010–2011 La Niña phenomenon, when several areas such as La Mojana were completely flooded for almost 2 years (Vargas, Hernández, & Pabón, ).…”