Low flows and downstream decline in phytoplankton contribute to impaired water quality in the lower Minnesota River

2019 ◽  
Vol 161 ◽  
pp. 262-273 ◽  
Author(s):  
Junna Wang ◽  
Zhonglong Zhang ◽  
Billy Johnson
2011 ◽  
Vol 2011 (2) ◽  
pp. 328-343
Author(s):  
James R. Rhea ◽  
Elizabeth Moran ◽  
Pradeep Mugunthan ◽  
David Glaser ◽  
Jeanne Powers

2012 ◽  
Vol 41 (5) ◽  
pp. 1459-1472 ◽  
Author(s):  
Victoria G. Christensen ◽  
Kathy E. Lee ◽  
James M. McLees ◽  
Scott L. Niemela

2018 ◽  
Vol 13 (4) ◽  
pp. 922-931 ◽  
Author(s):  
Ang Gao ◽  
Shiqiang Wu ◽  
Senlin Zhu ◽  
Zhun Xu

Abstract Statistical and wavelet analyses are useful tools for analyzing river water quality parameters. In this study, they were employed to study parameters including biochemical oxygen demand (BOD), dissolved oxygen (DO), nitrate (NO3), ammonium (NH4), phosphate (PO4), total phosphorus (TP), total Kjeldahl nitrogen (TKN), chlorophyll a (CHLA), total suspended solids (TSS) and water temperature (TEMP) monitored at five hydrologic stations on the Lower Minnesota River, USA. Strong positive correlations were observed between CHLA-BOD, TP-TKN, TP-TSS and TKN-TSS, with strong negative correlation between DO-TEMP. Daubechies wavelet at level 5 has been calculated for some key water quality parameters as it gives the finer scale approximation and decomposition of each water parameter. The results show that TEMP and DO have relative quasi-periodicity of about one year, while the quasi-periodicity of NH4 and PO4 are weaker than for TEMP and DO. Correlations between some parameters based on wavelet decomposition results are consistent. The fluctuation range characteristics of some parameters were also analyzed through wavelet decomposition.


GeoTextos ◽  
2014 ◽  
Vol 10 (1) ◽  
Author(s):  
Emilson Batista Da Silva ◽  
Creuza Santos Lage

O presente estudo trata da temática da relação sociedade natureza, considerando as repercussões da apropriação do espaço no estuário da Baía do Pontal-Ilhéus/BA. O recorte temporal adotado foi da década de 70 do século XX até o ano de 2012. A abordagem da pesquisa foi qualitativa, adotando, quando necessário, técnicas quantitativas. Os instrumentos de coleta constituíram-se de observação sistemática e entrevistas, além de pesquisa documental e bibliográfica. As análises efetuadas permitiram constatar que as intervenções socioespaciais na Baía do Pontal originam-se da construção do Porto de Ilhéus na porção norte, da degradação ambiental crescente das bacias dos rios tributários (rios Cachoeira, Santana e Itacanoeira) e do processo de ocupação do entorno da Baía. Essas pressões causaram alterações na dinâmica de circulação do estuário, levando-o a um estado de progradação de praia, intensificação no processo de assoreamento da baía, propensão à formação de mangues e comprometimento da qualidade da água, devido ao lançamento de esgotos. Abstract ENVIRONMENTAL IMPACTS IN THE PROCESS OF SOCIAL OWNERSHIP OF SPACE IN THE BAY OF THE PONTAL IN MUNICIPALITY OF ILHÉUS / BA This study is about the relationship between society and nature, considering the impact of the appropriation of space in the estuary of Pontal Bay -Ilhéus/BA. The time frame adopted begins with the 70s and extends until the year 2012. The research approach was qualitative, adopting quantitative techniques when necessary. The instruments of collection consisted of systematic observation and interview, plus documentary and bibliographic research. The analyzes showed evidence that the socio-spatial interventions in the Bay originate from the construction of the Port of Ilheus in the northern portion, from the growing, environmental degradation of river basins tributaries (rivers Cachoeira, Santana and Itacanoeira) and from the process of occupation surrounding the Bay. These pressures have caused changes in the dynamics of estuarine circulation, leading to a state of beach progradation, intensifying the process of silting up of the Bay, propension to formation of mangroves and impaired water quality due to discharge of sewage.


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