Linking landscape development intensity within watersheds to methyl-mercury accumulation in river sediments

Abstract

An indicator of the disturbance of natural systems, the landscape development intensity (LDI) index, was used to assess the potential for land-use within watersheds to influence the production/ accumulation of methyl-mercury (MeHg) in river sediments. Sediment samples were collected from locations impacted by well-identified land-use types within the Mobile-Alabama River Basin in Southeastern USA. The samples were analyzed for total-Hg (THg) and MeHg concentrations and the obtained values correlated to the calculated LDI indexes of the sampled watersheds to assess the impact of prevalent land use/land cover on MeHg accumulation in sediments. The results show that unlike THg, levels of MeHg found in sediments are impacted by the LDI indexes. Overall, certain combinations of land-use types within a given watershed appear to be more conducive to MeHg accumulation than others, therefore, pointing to the possibility of targeting land-use practices as potential means for reducing MeHg accumulation in sediments, and ultimately, fish contamination.

Understanding Food Web Mercury Accumulation Through Trophic Transfer and Carbon Processing along a River Affected by Recent Run-of-river Dams

“…River carbon and Hg cycles are also influenced by anthropogenic and natural disturbances in the surrounding watershed . For instance, logging and wildfires can lead to the leaching of Hg, organic matter, and nutrients into a river system, thereby affecting Hg concentrations in food webs .…”

“…14 River carbon and Hg cycles are also influenced by anthropogenic and natural disturbances in the surrounding watershed. 15 For instance, logging and wildfires can lead to the leaching of Hg, organic matter, and nutrients into a river system, thereby affecting Hg concentrations in food webs. 16 The construction of run-of-river facilities could exacerbate this phenomenon through the creation of permanent floodplains and sedimentation zones upstream of the dam, with yet unexplored effects on Hg cycling.…”

Effects of Landscape Development Intensity on River Water Quality in Urbanized Areas

“…This method is a good attempt to quantify anthropogenic influence based on primary indices of anthropogenic influences [46]. It has been directly used to evaluate the health of wetland ecosystem [44,49,50]. Some studies have developed the method by modifying the LDI coefficient and combining with other measure indexes, such as landscape matrix, forest cover, and road density to evaluate the current condition of wetlands [9,51,52].…”

Spatio-Temporal Variation in Mountainous Landscape Changes: A Case Study of Shizhu County

“…In 2005, the Global Land Project (GLP) was launched, with the "human-land coupled system" as the research goal, focusing on the driving mechanism and eco-environmental consequences of land-use changes [11]. The project pays special attention to the study of urban landscapes with the most frequent human activities at different geographic scales [12][13][14] and the study of the evolution of landscape patterns in typical regions and popular areas, covering watersheds [15][16][17][18], lakes [19][20][21], wetlands [22], plains [23], deltas [24], dams [25], and basins [26]. In addition, some scholars have studied the landscape of mountainous areas, such as the evolution of the land-use/-cover landscape patterns in karst mountains [27][28][29].…”