Effects of lake-basin morphological and hydrological characteristics on the eutrophication of shallow lakes in eastern China

Self Cite

Abstract:One common hypothesis is that wind can affect concentrations of nutrients (i.e., nitrogen and phosphorus) and chlorophyll-a (Chl-a) in shallow lakes. However, the tests of this hypothesis have yet to be conclusive in existing literature. The objective of this study was to use long-term data to examine how wind direction and wind speed affect the spatiotemporal variations of total nitrogen (TN), total phosphorus (TP) and Chl-a in Lake Tai, a typical shallow lake located in east China. The results indicated that the concentrations of nutrients and Chl-a tended to decrease from the northwest to the southeast of Lake Tai, with the highest concentrations in the two leeward bays (namely Meiliang Bay and Zhushan Bay) in the northwestern part of the lake. In addition to possible artificial reasons (e.g., wastewater discharge), the prevalent southeastward winds in warm seasons (i.e., spring and summer) and northwestward winds in cool seasons (i.e., fall and winter) might be the major natural factor for such a northwest-southeast decreasing spatial pattern. For the lake as a whole, the concentrations of TN, TP and Chl-a were highest for a wind speed between 2.1 and 3.2 m·s −1 , which can be attributed to the idea that the wind-induced drifting and mixing effects might be dominant in the bays while the wind-induced drifting and resuspension effects could be more important in the other parts of the lake. Given that the water depth of the bays was relatively larger than that of the other parts, the drifting and mixing effects were likely dominant in the bays, as indicated by the negative relationships between the ratios of wind speed to lake depth, which can be a surrogate for the vertical distribution of wind-induced shear stress and the TN, TP and Chl-a concentration. Moreover, the decreasing temporal trend of wind speed in combination with the ongoing anthropogenic activities will likely increase the challenge for dealing with the eutrophication problem of Lake Tai.

Section: Introductionmentioning

confidence: 99%

Spatiotemporal Distribution of Eutrophication in Lake Tai as Affected by Wind

Zhang

Wang

et al. 2017

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“…Our study showed that the TP-MonodModel has a better performance than the TN-MonodModel regardless of time interval (Figures 3 and 4). This inconsistency can be attributed to the distinctly different lake conditions (e.g., TN and TP concentrations) [26][27][28][29]. Xu et al [30] found that the threshold concentrations of TN and TP for harmful cyanobacterial blooms in Lake Tai are 0.8 mg·L , respectively.…”

Section: Discussionmentioning

confidence: 99%

Evaluation of a Modified Monod Model for Predicting Algal Dynamics in Lake Tai

Wang

et al. 2015

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Several modified versions of the Monod model have been proposed to simulate algal dynamics in lakes by keeping the parent model's advantages of simplicity and low data requirement. This study evaluated the performance of a widely-used modified Monod model in predicting algal dynamics at various time scales in Lake Tai, a typical shallow lake in east China, using multiple time series. Chlorophyll-a (Chl-a) concentration was used as a surrogate for algal (CyanoHABs: cyanobacterial harmful algal blooms) growth and the independent variables were total nitrogen (TN), total phosphorus (TP), and either water temperature or air temperature. The evaluation indicated that the model parameters could have distinctly different values, depending on whether or not constraints are imposed, time scales, and types of nutrients. The model performance varied in terms of time scales as well as magnitudes and fluctuations of Chl-a and TN or TP concentrations, achieving a relative OPEN ACCESSWater 2015, 7 3627 better performance for the monthly rather than three-day time scale and for the central part rather than bays of the study lake. The model with TP as the independent variable had a better performance than the model with TN as the independent variable, regardless of the time scale used. The temperature-nutrient interactions were important for algal growth when the temporal fluctuations of these two factors were large but the interactions could become minimal otherwise.

“…The region's biodiversity has also decreased due to water pollution [36]. These urgent problems concerning Poyang Lake have gained considerable attention because they have resulted in a serious threat to the approximately 12.4 million inhabitants that rely on this freshwater resource [10]. (a) Location of Poyang Lake-catchment, the main rivers and river gauging stations within its catchment; (b) Lake bathymetry, lake level gauging stations and river mouths.…”

Section: Study Site and Backgroundmentioning

confidence: 99%

“…The lake predominantly receives surface runoffs from the lake's catchment rivers and subsequently flows into the Yangtze River [9]. Extensive efforts have been carried out to investigate the water quality status of Poyang Lake, including field measurements and analysis [10,11], the investigation of major pollutants and pollution sources [12,13], and the analysis of the factors influencing water quality [14,15], which have provided various management strategies for local governments. With the rapid economic development around the lake, an increasing numbers of factories and communities are gathering around Poyang Lake and are discharging pollutants of various types into the lake [16].…”

Section: Introductionmentioning

confidence: 99%

“…Simultaneously, with the increase in waterway transportation, the number of accidental releases of hazardous chemicals into the lake is also increasing [17]. To the best of our knowledge, the water quality and the associated ecosystem are being seriously threatened during the lake flood period (July-September), due to the continuous accumulation of catchment river-transported pollutants along with large amounts of river discharges [10]. In addition, the extent of lake flooding with slow water flows significantly increases pollution risk of the already environmentally degraded Poyang Lake [11].…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Estimation of Transport Trajectory and Residence Time in Large River–Lake Systems: Application to Poyang Lake (China) Using a Combined Model Approach

Yao

2015

Abstract:The biochemical processes and associated water quality in many lakes mainly depend on their transport behaviors. Most existing methodologies for investigating transport behaviors are based on physically based numerical models. The pollutant transport trajectory and residence time of Poyang Lake are thought to have important implications for the steadily deteriorating water quality and the associated rapid environmental changes during the flood period. This study used a hydrodynamic model (MIKE 21) in conjunction with transport and particle-tracking sub-models to provide comprehensive investigation of transport behaviors in Poyang Lake. Model simulations reveal that the lake's prevailing water flow patterns cause a unique transport trajectory that primarily develops from the catchment river mouths to the downstream area along the lake's main flow channels, similar to a river-transport behavior. Particle tracking results show that the mean residence time of the lake is 89 days during July-September. The effect of the Yangtze River (the effluent of the lake) on the residence time is stronger than that of the catchment river inflows. The current study represents a first attempt to use a combined model approach to provide insights into the transport behaviors for a large river-lake system, given proposals to manage the pollutant inputs both directly to the lake and catchment rivers. OPEN ACCESSWater 2015, 7 5204