Spatial patterns of some trace elements in four Swedish stream networks

Abstract

Four river basins in southern Sweden, with catchment sizes from 0.3 to 127 km² (median 1.9), were sampled in October~2007. The 243 samples were analysed for 26 trace elements (Ag, As, Au, Ba, Be, Bi, Cd, Co, Cr, Cu, Ga, Ge, In, La, Li, Mo, Ni, Pb, Sb, Se, Sn, Tl, Ti, U, V and Zn) to identify spatial patterns within drainage networks. The range and median of each element were defined for different stream orders, and relationships to catchment characteristics, including deposition history, were explored. The sampling design made it possible to compare the differences along 40 stream reaches, above and below 53 stream junctions with 107 tributaries and between the 77 inlets and outlets of 36 lakes. The largest concentration differences (at reaches, junctions and lakes) were observed for lakes, with outlets usually having lower concentration compared to the inlets for As, Ba, Be, Bi, Cd, Co, Cr, Ga, Ge, Ni, Pb, Sn, Ti, Tl, U, V and Zn. Significantly lower concentrations were observed for Cd and Co when comparing headwaters with downstream sites in each catchment. Common factor analysis (FA) revealed that As, Bi, Cr, Ga, Ge, Tl and V co-vary positively with Al, Fe and total organic carbon (TOC) and negatively with La, Li and pH. The strong removal of a large number of trace elements when passing through lakes is evident though in the FA, where lake surface coverage plots opposite to many of those elements. Forest volume does not respond in a similar systematic fashion and, surprisingly, the amount of wetland does not relate strongly to either Fe or TOC at any of the rivers. A better understanding of the quantitative removal of organic carbon and iron will aid in understanding trace element fluxes from landscapes rich in organic matter and iron

Trace element transport in western Siberian rivers across a permafrost gradient

“…In this regard, the WSL allows for study of the mobilization of organic-bound metals from frozen soil to the river across more than 1500 km gradient of permafrost coverage (absent, sporadic, isolated, discontinuous and continuous), vegetation (southern and middle taiga to tundra) and climate (0 to −9 • C MAAT) while remaining within relatively homogeneous nature of underlining lithology (sands and clays), soils (peat and podzols) and runoff (200 to 300 mm yr −1 ). Note that, in contrast to extensive studies of TEs in rivers and streams of boreal regions of Scandinavia (Ingri et al, 2000(Ingri et al, , 2005Wallstedt et al, 2010;Huser et al, 2011Huser et al, , 2012Oni et al, 2013;Tarvainen et al, 1997;Lidman et al, 2011Lidman et al, , 2012Lidman et al, , 2014Temnerud et al, 2013), Alaska (Rember and Trefry, 2004), Canada (Wadleigh et al, 1985;Gaillardet et al, 2003;Millot et al, 2003), central Siberia (Pokrovsky et al, 2006;Bagard et al, 2011Bagard et al, , 2013 and European Russia, 2010; Vasyukova et al, 2010), even punctual measurements of TEs in watersheds of large western Siberian rivers (Ob, Nadym, Taz and Pur basins) with the exceptions of the Ob and Irtush rivers (Moran and Woods, 1997;Alexeeva et al, 2001;Gordeev et al, 2004) are lacking. Moreover, similar to other Siberian rivers (Pokrovsky et al, 2006;Huh and Edmond, 1999;Huh et al, 1998;Dessert et al, 2009) seasonally resolved measurements of TEs in WSL rivers are absent.…”

“…12. The main difference of WSL permafrostbearing regions from other, Scandinavian, Alaskan, and central Siberian soils is the location of an active (seasonally unfrozen) layer within the organic rather than mineral horizon (Tyrtikov, 1973;Khrenov, 2011). As a result, unlike that of the non-peatland permafrost environments (i.e., Keller et al, 2007;Barker et al, 2014), element mobilization to the river over the full duration of the open-water season occurs essentially from the organic horizon.…”

“…Indeed, given the 1 to 3 m thickness of the peat even in the northern part of the WSL (Vasil'evskaya et al, 1986;Kremenetski et al, 2003) and the typical active layer thickness of 50 ± 30 cm (Tyrtikov, 1973;Khrenov, 2011;Novikov et al, 2009), in the region of permafrost development, downward-migrating peat soil interstitial solutions will not likely contact the underlying mineral horizon. The consequences of this reduced pathway are twofold.…”

Trace elements transport in western Siberia rivers across a permafrost gradient

“…In this regard, the WSL allows for study of the mobilization of organic-bound metals from frozen soil to the river across more than 1500 km gradient of permafrost coverage (absent, sporadic, isolated, discontinuous and continuous), vegetation (southern and middle taiga to tundra) and climate (0 to −9 • C MAAT) while remaining within relatively homogeneous nature of underlining lithology (sands and clays), soils (peat and podzols) and runoff (200 to 300 mm yr −1 ). Note that, in contrast to extensive studies of TEs in rivers and streams of boreal regions of Scandinavia (Ingri et al, 2000(Ingri et al, , 2005Wallstedt et al, 2010;Huser et al, 2011Huser et al, , 2012Oni et al, 2013;Tarvainen et al, 1997;Lidman et al, 2011Lidman et al, , 2012Lidman et al, , 2014Temnerud et al, 2013), Alaska (Rember and Trefry, 2004), Canada (Wadleigh et al, 1985;Gaillardet et al, 2003;Millot et al, 2003), central Siberia (Pokrovsky et al, 2006;Bagard et al, 2011Bagard et al, , 2013 and European Russia, 2010; Vasyukova et al, 2010), even punctual measurements of TEs in watersheds of large western Siberian rivers (Ob, Nadym, Taz and Pur basins) with the exceptions of the Ob and Irtush rivers (Moran and Woods, 1997;Alexeeva et al, 2001;Gordeev et al, 2004) are lacking. Moreover, similar to other Siberian rivers (Pokrovsky et al, 2006;Huh and Edmond, 1999;Huh et al, 1998;Dessert et al, 2009) seasonally resolved measurements of TEs in WSL rivers are absent.…”

Submerged Carbonate Banks Aggregate Pelagic Megafauna in Offshore Tropical Australia

“…We used these to build replicate GAMMs, keeping track of all bootstrap outputs and predictions, and quantifying uncertainty as the robust coefficient of variation (rCV) across Bootstrap replicates. rCV is a modified form of the traditional CV which is less sensitive to skewness and outliers (Arachchige et al, 2019) and is calculated as rCV = 100 × normalized IQR/median, where IQR is the interquartile range (25-75 percentile) and the normalized IQR is 0.7413 × IQR (Temnerud et al, 2013).…”