scholarly journals Wind Effects for Floating Algae Dynamics in Eutrophic Lakes

2021 ◽  
Vol 13 (4) ◽  
pp. 800
Author(s):  
Yuchao Zhang ◽  
Steven Loiselle ◽  
Kun Shi ◽  
Tao Han ◽  
Min Zhang ◽  
...  
Keyword(s):  
Climate Change ◽  
Wind Speed ◽  
Vertical Distribution ◽  
Algal Blooms ◽  
Algal Bloom ◽  
Lake Taihu ◽  
Early Warning Systems ◽  
Eutrophic Lakes ◽  
Algae Blooms ◽  
The Vertical Distribution

Wind-speed decline is an important impact of climate change on the eastern Asian atmospheric circulation. Although wind does not determine algae biomass in eutrophic lakes, it is a decisive factor in the formation and severity of algae blooms. Based on 2000–2018 MODIS images, this study compared the effects of wind speed on algal blooms in three typical eutrophic lakes in China: Lake Taihu, Lake Chaohu and Lake Dianchi. The results indicate that climate change has different effects on the wind speed of the three lakes, but a common effect on the vertical distribution of algae. A wind speed of 3.0 m/s was identified as the critical threshold in the vertical distribution of chlorophyll-a concentrations in the three study lakes. The basic characteristics of the periodic variation of wind speed were different, but there was a significant negative correlation between wind speed and floating algal bloom area in all three lakes. In addition, considering lake bathymetry, wind direction could be used to identify locations that were particularly susceptible to algae blooms. We estimated that algal bloom conditions will worsen in the coming decades due to the continuous decline of wind, especially in Lake Taihu, even though the provincial and national governments have made major efforts to reduce eutrophication drivers and restore lake conditions. These results suggest that early warning systems should include a wind-speed threshold of 3.0 m/s to improve control and mitigation of algal blooms on these intensively utilized lakes.

scholarly journals Cyanopeptides Restriction and Degradation Co-mediate Microbiota Assembly During a Freshwater Cyanobacterial Harmful Algal Bloom (CyanoHAB)

2022 ◽  
Author(s):  
Han Gao ◽  
Ze Zhao ◽  
Lu Zhang ◽  
Feng Ju
Keyword(s):  
Community Assembly ◽  
Harmful Algal Blooms ◽  
Algal Blooms ◽  
Algal Bloom ◽  
Lake Taihu ◽  
Harmful Algal Bloom ◽  
Size Fraction ◽  
Freshwater Ecosystems ◽  
Cyanobacterial Harmful Algal Blooms ◽  
Microbiota Diversity

Cyanobacterial harmful algal blooms (CyanoHABs) are globally intensifying and exacerbated by climate change and eutrophication. However, microbiota assembly mechanisms underlying CyanoHABs remain scenario specific and elusive. Especially, cyanopeptides, as a group of bioactive secondary metabolites of cyanobacteria, could affect microbiota assembly and ecosystem function. Here, the trajectory of cyanopeptides were followed and linked to microbiota during Microcystis-dominated CyanoHABs in lake Taihu, China. The most abundant cyanopeptide classes detected included microginin, spumigin, microcystin, nodularin and cyanopeptolin with total MC-LR-equivalent concentrations between 0.23 and 2051.54 ppb, of which cyanotoxins beyond microcystins (e.g., cyanostatin B and nodularin_R etc.) far exceeded reported organismal IC50 and negatively correlated with microbiota diversity, exerting potential collective eco-toxicities stronger than microcystins alone. The microbial communities were differentiated by size fraction and sampling date throughout CyanoHABs, and surprisingly, their variances were better explained by cyanopeptides (19-38%) than nutrients (0-16%). Cyanopeptides restriction (e.g., inhibition) and degradation are first quantitatively verified as the deterministic drivers governing community assembly, with stochastic processes being mediated by interplay between cyanopeptide dynamics and lake microbiota. This study presents an emerging paradigm in which cyanopeptides restriction and degradation co-mediate lake water microbiota assembly, unveiling new insights about the ecotoxicological significance of CyanoHABs to freshwater ecosystems.

scholarly journals Vertical distribution of Microcystis colony size in Lake Taihu: Its role in algal blooms

2014 ◽  
Vol 40 (4) ◽  
pp. 949-955 ◽  
Author(s):  
Wei Zhu ◽  
Ming Li ◽  
Yonggang Luo ◽  
Xiaoxuan Dai ◽  
Lili Guo ◽  
...  
Keyword(s):  
Vertical Distribution ◽  
Colony Size ◽  
Algal Blooms ◽  
Lake Taihu

scholarly journals ESTIMATION OF PM<sub>2.5</sub> VERTICAL DISTRIBUTION USING CUSTOMIZED UAV AND MOBILE SENSORS IN BRGY. UP CAMPUS, DILIMAN, QUEZON CITY

2018 ◽  
Vol XLII-4/W9 ◽  
pp. 89-103 ◽  
Author(s):  
J. B. Babaan ◽  
J. P. Ballori ◽  
A. M. Tamondong ◽  
R. V. Ramos ◽  
P. M. Ostrea
Keyword(s):  
Air Quality ◽  
Wind Speed ◽  
Relative Humidity ◽  
Vertical Distribution ◽  
Unmanned Aerial Vehicle ◽  
Meteorological Parameters ◽  
Flying Height ◽  
Quezon City ◽  
Aerial Vehicle ◽  
The Vertical Distribution

<p><strong>Abstract.</strong> As the unmanned aerial vehicle (UAV) technology has gained popularity over the years, it has been introduced for air quality monitoring. This study demonstrates the feasibility of customized UAV with mobile monitoring devices as an effective, flexible, and alternative means to collect three-dimensional air pollutant concentration data. This also shows the vertical distribution of PM concentration and the relationship between the PM<sub>2.5</sub> vertical distribution and the meteorological parameters within 500<span class="thinspace"></span>m altitude on a single flight in UP Diliman, Quezon City. Measurement and mapping of the vertical distribution of particulate matter (PM)<sub>2.5</sub> concentration is demonstrated in this research using integrated air quality sensors and customized Unmanned Aerial Vehicle. The flight covers an area with a radius of 80 meters, following a cylindrical path with 40-meter interval vertically. The PM<sub>2.5</sub> concentration values are analyzed relative to the meteorological parameters including air speed, pressure, temperature, and relative humidity up to a 500<span class="thinspace"></span>meter-flying height in a single flight in Barangay UP Campus, UP Diliman, Quezon City. The study shows that generally, the PM<sub>2.5</sub> concentration decreases as the height increases with an exception in the 200&amp;ndash;280<span class="thinspace"></span>m above ground height interval due to a sudden change of atmospheric conditions at the time of the flight. Using correlation and regression analysis, the statistics shows that PM<sub>2.5</sub> concentration has a positive relationship with temperature and a negative relationship with relative humidity and wind speed. As relative humidity and wind speed increases, PM<sub>2.5</sub> decreases, while as temperature increases, PM<sub>2.5</sub> also increases.</p>

scholarly journals MODIS-Satellite-Based Analysis of Long-Term Temporal-Spatial Dynamics and Drivers of Algal Blooms in a Plateau Lake Dianchi, China

2019 ◽  
Vol 11 (21) ◽  
pp. 2582 ◽  
Author(s):  
Yuanyuan Jing ◽  
Yuchao Zhang ◽  
Minqi Hu ◽  
Qiao Chu ◽  
Ronghua Ma
Keyword(s):  
Spatial Distribution ◽  
Influencing Factors ◽  
Algal Blooms ◽  
Algal Bloom ◽  
Spatial Dynamics ◽  
Strong Positive Correlation ◽  
Eutrophic Lakes ◽  
Lake Dianchi ◽  
Plateau Lake

Algal blooms in eutrophic lakes have been a global issue to environmental ecology. Although great progress on prevention and control of algae have been made in many lakes, systematic research on long-term temporal-spatial dynamics and drivers of algal blooms in a plateau Lake Dianchi is so far insufficient. Therefore, the algae pixel-growing algorithm (APA) was used to accurately identify algal bloom areas at the sub-pixel level on the Moderate Resolution Imaging Spectroradiometer (MODIS) data from 2000 to 2018. The results showed that algal blooms were observed all year round, with a reduced frequency in winter–spring and an increased frequency in summer–autumn, which lasted a long time for about 310–350 days. The outbreak areas were concentrated in 20–80 km2 and the top three largest areas were observed in 2002, 2008, and 2017, reaching 168.80 km2, 126.51 km2, and 156.34 km2, respectively. After deriving the temporal-spatial distribution of algal blooms, principal component analysis (PCA) and redundancy analysis (RDA) were applied to explore the effects of meteorological, water quality and human activities. Of the variables analyzed, mean temperature (Tmean) and wind speed (WS) were the main drivers of daily algal bloom areas and spatial distribution. The precipitation (P), pH, and water temperature (WT) had a strong positive correlation, while WS and sunshine hours (SH) had a negative correlation with monthly maximum algal bloom areas and frequency. Total nitrogen (TN) and dissolved oxygen (DO) were the main influencing factors of annual frequency, initiation, and duration of algal blooms. Also, the discharge of wastewater and the southwest and southeast monsoons may contribute to the distribution of algal blooms mainly in the north of the lake. However, different regions of the lake show substantial variations, so further zoning and quantitative joint studies of influencing factors are required to more accurately understand the true mechanisms of algae in Lake Dianchi.

scholarly journals BLOWN SAND ON BEACHES

1982 ◽  
Vol 1 (18) ◽  
pp. 73
Author(s):  
Susumu Kubota ◽  
Kiyoshi Horikawa ◽  
Shintaro Hotta
Keyword(s):  
Wind Speed ◽  
Wind Tunnel ◽  
Vertical Distribution ◽  
Shear Velocity ◽  
Wind Tunnel Experiment ◽  
Transport Rate ◽  
Sand Transport ◽  
Sand Transport Rate ◽  
Empirical Coefficients ◽  
The Vertical Distribution

The blown sand transport rate and the vertical and shore-normal distributions of the wind speed were measured simultaneously on a windy beach. The sand transport rate was measured with conventional total quantity-type traps and with a large trap in the form of a trench. The vertical distribution of the wind speed was measured using an ultrasonic anemometer array consisting of six meters. The distribution of wind speed at a height of 1 m in a section normal to the shoreline was measured with five ultrasonic anemometers. A logarithmic law for the vertical distribution of the wind speed was satisfied, and the wind speed in the section normal to the shoreline was almost constant. The Kawamura and Bagnold formulae were found to predict well the sand transport rate. The trench trap and conventional traps gave empirical coefficients of 1.5 and 1.0, respectively, for the sand transport rate averaged over a section normal to the shoreline. The lower value determined with the conventional traps (1.0) is attributed to their inefficiency compared with the trench trap. In order to obtain data at high shear velocities, a wind tunnel experiment was carried out. This experiment showed that both the Kawamura and Bagnold formulae were valid in the range between 60 to 300 cm/s in the wind shear velocity. The empirical coefficient in the laboratory experiments was 1.0: the difference between the field result with the trench trap and the wind tunnel experiment is attributed to the fluctuations in natural wind.

scholarly journals Dependence of the vertical distribution of bromine monoxide in the lower troposphere on meteorological factors such as wind speed and stability

2015 ◽  
Vol 15 (4) ◽  
pp. 2119-2137 ◽  
Author(s):  
P. K. Peterson ◽  
W. R. Simpson ◽  
K. A. Pratt ◽  
P. B. Shepson ◽  
U. Frieß ◽  
...  
Keyword(s):  
Wind Speed ◽  
Vertical Distribution ◽  
Degrees Of Freedom ◽  
Atmospheric Stability ◽  
Lower Troposphere ◽  
Optimal Estimation ◽  
Vertical Column ◽  
Vertical Column Density ◽  
Halogen Activation ◽  
The Vertical Distribution

Abstract. Multiple axis differential absorption spectroscopy (MAX-DOAS) measurements of bromine monoxide (BrO) probed the vertical structure of halogen activation events during March–May 2012 at Barrow, Alaska. An analysis of the BrO averaging kernels and degrees of freedom obtained by optimal-estimation-based inversions from raw MAX-DOAS measurements reveals the information is best represented by reducing the retrieved BrO profile to two quantities: the integrated column from the surface through 200 m (VCD200 m), and the lower tropospheric vertical column density (LT-VCD), which represents the integrated column of BrO from the surface through 2 km. The percentage of lower tropospheric BrO in the lowest 200 m was found to be highly variable ranging from shallow layer events, where BrO is present primarily in the lowest 200 m, to distributed column events where BrO is observed at higher altitudes. The highest observed LT-VCD events occurred when BrO was distributed throughout the lower troposphere, rather than concentrated near the surface. Atmospheric stability in the lowest 200 m influenced the percentage of LT-VCD that is in the lowest 200 m, with inverted temperature structures having a first-to-third quartile range (Q1–Q3) of VCD200 m/LT-VCD from 15–39%, while near-neutral-temperature structures had a Q1–Q3 range of 7–13%. Data from this campaign show no clear influence of wind speed on either lower tropospheric bromine activation (LT-VCD) or the vertical distribution of BrO, while examination of seasonal trends and the temperature dependence of the vertical distribution supported the conclusion that the atmospheric stability affects the vertical distribution of BrO.

scholarly journals The Vertical Distribution of Sediment Archaeal Community in the “Black Bloom” Disturbing Zhushan Bay of Lake Taihu

Archaea ◽  
2016 ◽  
Vol 2016 ◽  
pp. 1-8 ◽  
Author(s):  
Xianfang Fan ◽  
Peng Xing
Keyword(s):  
Surface Layer ◽  
Vertical Distribution ◽  
Lake Taihu ◽  
Archaeal Community ◽  
Cyanobacterial Blooms ◽  
Bloom Formation ◽  
Significant Difference ◽  
Different Depths ◽  
Biomass Transformation ◽  
The Vertical Distribution

Using the Illumina sequencing technology, we investigated the vertical distribution of archaeal community in the sediment of Zhushan Bay of Lake Taihu, where the black bloom frequently occurred in summer. Overall, the Miscellaneous Crenarchaeotal Group (MCG), Deep Sea Hydrothermal Vent Group 6 (DHVEG-6), andMethanobacteriumdominated the archaeal community. However, we observed significant difference in composition of archaeal community among different depths of the sediment. DHVEG-6 dominated in the surface layer (0–3 cm) sediment.Methanobacteriumwas the dominating archaeal taxa in the L2 (3–6 cm) and L3 (6–10) sediment. MCG was most abundant in the L4 (10–15 cm) and L5 (15–20 cm) sediment. Besides, DHVEG-6 was significantly affected by the concentration of total phosphorus (TP). And loss on ignition (LOI) was an important environmental factor forMethanobacterium. As the typical archaeal taxa in the surface layer sediment, DHVEG-6 andMethanobacteriummight be more adapted to abundant substrate supply from cyanobacterial blooms and take active part in the biomass transformation. We propose that DHVEG-6 andMethanobacteriumcould be the key archaeal taxa correlated with the “black bloom” formation in Zhushan Bay.

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