Aeolian input of phosphorus to a remote lake induced increase of primary production at the Tibetan Plateau

Abstract

A complete record derived from a core dated by both ²¹⁰Pb and ¹³⁷Cs chronologies from Lake Ngoring at the key headwater areas of the Yellow River provides new insight into the increase of primary production induced by aeolian input of phosphorus. This study showed that there was an inflection in the early 1960s, before which total phosphorus (TP), calcium-bound P (Ca-P), and exchangeable P (Ex-P) remained relatively steady or slowly increased (averages 403, 90, and 38 mg kg⁻¹, respectively). However, continued increases of TP, Ca-P, and Ex-P were found thereafter, reaching 460, 110, and 45 mg kg⁻¹, respectively. This distribution pattern was attributed to the increasing anthropogenic input of aeolian phosphorus, probably due to land cover changes, and to sustained urbanization/industrialization and agricultural intensification in neighboring areas. Accordingly, with the increase of limiting nutrient (P), sedimentary organic carbon increased from 7.1 g kg⁻¹ (1960) to 12.0 g kg⁻¹ (2000), nearly a factor of 2, which revealed explicitly that the primary production of Lake Ngoring was enhanced greatly by aeolian P input increase and resulted in the accelerated evolvement process of this remote alpine lake.