The potential applications of real-time monitoring of water quality in a large shallow lake (Lake Taihu, China) using a chromophoric dissolved organic matter fluorescence sensor.

Yunlin Zhang,Kun Shi,Boqiang Qin,Cheng Niu,Xiaohan Liu,Yongqiang Zhou

doi:10.3390/s140711580

Abstract

This study presents results from field surveys performed over various seasons in a large, eutrophic, shallow lake (Lake Taihu, China) using an in situ chromophoric dissolved organic matter (CDOM) fluorescence sensor as a surrogate for other water quality parameters. These measurements identified highly significant empirical relationships between CDOM concentration measured using the in situ fluorescence sensor and CDOM absorption, fluorescence, dissolved organic carbon (DOC), chemical oxygen demand (COD) and total phosphorus (TP) concentrations. CDOM concentration expressed in quinine sulfate equivalent units, was highly correlated with the CDOM absorption coefficient (r2 = 0.80, p < 0.001), fluorescence intensities (Ex./Em. 370/460 nm) (r2 = 0.91, p < 0.001), the fluorescence index (r2 = 0.88, p < 0.001) and the humification index (r2 = 0.78, p < 0.001), suggesting that CDOM concentration measured using the in situ fluorescence sensor could act as a substitute for the CDOM absorption coefficient and fluorescence measured in the laboratory. Similarly, CDOM concentration was highly correlated with DOC concentration (r2 = 0.68, p < 0.001), indicating that in situ CDOM fluorescence sensor measurements could be a proxy for DOC concentration. In addition, significant positive correlations were found between laboratory CDOM absorption coefficients and COD (r2 = 0.83, p < 0.001), TP (r2 = 0.82, p < 0.001) concentrations, suggesting a potential further application for the real-time monitoring of water quality using an in situ CDOM fluorescence sensor.

Highlights

Lakes and reservoirs are abundant natural systems that provide a wide range of essential ecosystem services, ranging from drinking water and food to transportation and recreation [1]
We introduced the fluorescence index and the humification index (HIX: FI254) to determine whether chromophoric dissolved organic matter (CDOM) concentration measured using in situ fluorescence sensor could replace these indices to characterize CDOM
There was a highly positive correlation between CDOM concentration measured using in situ fluorescence sensor and a(370) (Figure 2a)

Summary

Introduction

Lakes and reservoirs are abundant natural systems that provide a wide range of essential ecosystem services, ranging from drinking water and food to transportation and recreation [1]. Lakes and reservoirs are important sentinels, integrators, and regulators of climate change [2]. In the past few decades, many lakes and reservoirs have undergone increasing eutrophication, water quantity decrease and water quality deterioration due to the dual pressures of anthropogenic activities and climate change [3,4,5]. Some lakes and reservoirs have experienced phytoplankton blooms and drinking water crises. In the past decades, field measurements for water quality evaluation have typically depended upon costly time- and labor-intensive on-site sampling and data collection and transport to land-based or shipboard laboratories for evaluation. Satellite-based remote sensing using the Sea-viewing Wide Field-of-view Sensor (SeaWiFS), Moderate Resolution Imaging

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Conclusion