Phosphorus transfer across boundaries: from basin soils to river bed sediments

Abstract

Purpose The study of phosphorus (P) transfer from soils to rivers is a subject of interest as there is a clear relation between land use and water quality. P transfer in the soil/sediment system was evaluated by comparing the concentrations of total (P T ) and bioavailable P (P A ). Materials and methods Phosphorus concentrations were measured in three different compartments following the natural transport route in a basin: soils, suspended and riverbed sediments. Soils were sampled from five different types of land cover: cropped land, forest, pasture, river banks and road taluses (roadside open earthen ditches). Samples were taken from two different sub-basins: the Grande and the upper Anllóns sub-basins. Results and discussion The highest concentrations of P were found in the suspended sediments, followed by the riverbed sediments and the soils. The cropped and pasture soils contained the highest amounts of P. The P A /P ratio was very low in the soils (<0.3), but was significantly higher in the sediments, particularly in the suspended sediments (0.67). The concentration of P A was also significantly higher in the suspended sediments and riverbed sediments than in the river basin soils, with concentration factors of 300% for P and 2,600% for P A , either in suspended and bed sediments being slightly higher in the suspended than in the bed sediments , which suggests the potential environmental risk of P transfer to the river courses via soil. Conclusions Comprehensive studies involving P transfer across soils-suspended sediments-bed sediments are scarce, highlighting the innovative nature of the present study. The results obtained will allow the evaluation of the impact of different types of land use on the sustainability of the aquatic ecosystem at a catchment scale.

Spatial and temporal variations in nutrients in water and riverbed sediments at the mouths of rivers that enter Lake Hachiro, a shallow eutrophic lake in Japan

“…Because the nutrients and sediments transported from watersheds depend strongly on rate of loading and of sediment erosion into rivers (Lukkari et al, 2008;Pacini and Gächter, 1999) and on watershed characteristics such as hydrology, geology, soils, topography, and land use (Iglesias et al, 2011;Jiang et al, 2010Jiang et al, , 2012Woli et al, 2004), they are expected to vary in space and in time in a lake. Jin et al (2006) reported spatial variation in different P fractions in sediments and a relationship between these variations and the trophic status of different parts of Taihu Lake.…”

Biotic and Abiotic Factors Influencing Arsenic Biogeochemistry and Toxicity in Fluvial Ecosystems: A Review

“…Arsenic release is also promoted in high ionic strength conditions, as it is characteristic of estuarine environments where the mixture of fresh and marine waters occurs [73]. The release of arsenic is favored by the presence of phosphate, showing high concentrations in some sections of the river [194][195][196], coming from wastewaters discharged into the river course and fertilizers eroded or leached from the soils of the basin. Interestingly, although phosphate favors arsenic release from the Anllóns sediments, it was shown in Microtox ® bioassays that it counteracts the acute toxicity of arsenate, but has no effect on the toxicity of arsenite and DMA V [197].…”

Sieved Transport and Redistribution of Bioavailable Phosphorus from Watershed with Complex River Networks to Lake

“…Previous studies revealed that fine particles are selectively eroded from the soil surface and easily transported downstream and exhibit preferential export of nonapatite P (NaOH 25 -P, BD-P, and NaOH 85 -P), resulting in higher proportions of labile or bioavailable forms of inorganic-P in lakes or rivers related to the basin soils. 30,31 This could partially explain the spatial patterns of sediment P fractionation in the river networks across the Lake Taihu basin, where the fraction of HCl-P was predominant in the upstream. In the upstream areas of agriculture, soil erosion could also be important to the load of coarse particles with a short transport pathway or due to bank failure, 31,32 resulting in a higher proportion of HCl-P from nonpoint sources.…”