Humic substances—part 7: the biogeochemistry of dissolved organic carbon and its interactions with climate change

Abstract

The key controls on allochthonous DOC quality, quantity, and catchment export in response to climate change are still not fully understood. More detailed knowledge of these processes is required so that changes in DOC and its interactions with nutrients and trace metals can be better predicted based on changes caused by changing climate. More studies are needed concerning the effects of trace metals on DOC, the effects of changing DOC quality and quantity on trace metals and nutrients, and how runoff and temperature-related changes in DOC export affect metal and nutrient export to rivers and lakes.

Long-term Trends of Organic Carbon Concentrations in Freshwaters: Strengths and Weaknesses of Existing Evidence

“…The root causes of this increase remain unclear. Although a few review articles on the subject have been published [3][4][5][6], they largely uncritically accept the universality of DOC increase, collate published results and list suggested causes. They very seldom address issues related to the methodology used, quality of the results, etc.…”

Developmental Changes in the Historical and Present-Day Trophic Status of Brown Water Lakes. Are Humic Water Bodies a Uniform Aquatic Ecosystem?

“…Climate change models predict that higher temperatures are likely to occur over most of the boreal forests in North America, Europe, and Asia (Porcal et al 2009) which can cause modifications in habitats making them less favorable for dystrophy and leading to disappearance of humic lakes. Simultaneously, over the past few decades, phenomena that are advantageous for the formation of humic lakes have been observed; namely, the intense export of organic matter to surface waters (Freeman et al 2001;Roulet and Moore 2006;Evans et al 2012).…”

Increasing dissolved organic carbon concentrations in freshwaters: what is the actual driver?

“…These differences in repor ting methods and varying record length com plicate the comparison of the results among studies and regional generalization. Due to contradictory findings reported in literature, Porcal et al (2009) point out that descriptive studies have their limitations and that de tailed modelling studies that integrate key mechanisms are considered necessary to al low testing of various scenarios. They also mention the need for more studies investiga ting how run-off and temperature related changes in DOC affect metal and nutrient export to rivers and lakes.…”