The utility of the viral MST tools and the prevalence and abundance of specific human and animal viruses in the five river catchments and adjacent seawater, which is impacted by riverine contributions from the upstream catchments, were examined.
A better understanding of coastal Hg inputs to the open ocean and their historical trends is needed, particularly for the North Atlantic and the Arctic Ocean where the relatively large riverine contributions are thought to be a significant Hg source.
They are mainly used here, in conjunction with Chl a measurements, to constrain an upper limit of autochthonous contribution to riverine OC pools.
It indicated that WWTP effluents made only a moderate contribution to riverine discharge (21% for PFOA, 6% for PFOS), while atmospheric deposition to the watershed was 1 2 orders of magnitude greater than WWTP discharges.
In riverine wetlands without plankton, contributions of detrital carbon to fish communities decreased significantly in response to watershed disturbance that reflected nutrient loading.
From the above reasoning, we speculate there is negligible contribution of autochthonous C to riverine OC pools of these Malagasy basins, and hypothesise that δC signatures of riverine particulate and DOC will be largely representative of the relative proportion of C originating from the two terrestrial end-members, that is, C3 and C4 vegetation.
Generally, the contribution of cyclic salts to riverine dissolved salt loads is expected to decrease with increasing distance from the sea.
This conclusion is reinforced by the indirect contribution of atmospheric deposition through riverine input as indicated by the Oder catchment mass balance.
Our data suggest negligible contribution of Chl a to riverine POC, with mg POC mg Chl a consistently above 1,000 in both basins, and only once was the mg POC mg Chl a less than 200 (in the main channel of the lower Betsiboka during dry season).
Having already discounted significant contribution of algal C sources to riverine OC pools in the Rianila basin, it is unsurprising that riverine DOC and POC δC values reflect the dominance of C3 vegetation in this system.
Despite these findings, little systematic analysis of the proportional contribution of these landscape units to riverine organic C pools has been conducted (for example, Ballester and others 2013).
