Seasonal variation of suspended sediment and its relationship with turbidity in Cam - Nam Trieu estuary, Hai Phong (Vietnam)

We analyzed the seasonal variation of suspended sediment and its relationship with Turbidity in Cam - Nam Trieu estuary based on data measured during three different seasons: Early wet season (May 2015), wet season (September 2015) and dry season (January 2016). The results highlighted the seasonal variation of suspended particle matter (SPM) concentrations with river flow. The average SPM concentration was highest during the dry season, with 62.95 mg/L. They were not significantly different between the early wet and wet seasons, with 59.65 mg/L and 50.94 mg/L, respectively. This study also demonstrated a strong dependence between SPM and Turbidity in the study area. The coefficients of determination varied from 0.867 to 0.971 (linear relationship), and from 0.95 to 0.991 (proportional relationship). Therefore, turbidity can be used to estimate SPM concentration. However, this relationship changed markedly with the seasons, and hence when determining SPM concentration, seasonal factors must be considered.

Research on extracting suspended particle matter content (SPM) based VNRedSat-1 imagery for monitoring water quality

Currently, VNREDSAT 1 data have been commonly applied in studying disciplines of landscapes or socioeconomy. Nevertheless, there are limited studies using these data in water quality management. This article focuses on estimating amounts of SPM (Suspended Particulate Matters) from VNREDSAT 1 in Thi Vai river basin based on a popular formula with on - site adjustments. Results were validated by field data with an relative value R2 = 0. 79. This value represents that there is a potential of applying VNREDSAT 1 in studying SPM in water depending on certain circumstances of accuracy.

Mercury bioaccumulation in fishes of a paddy field in Southern of Brazil

Aim: The aim of present study was to evaluate the Hg concentration in two species of fish (Astyanax sp and Corydoras paleatus) and its potential use as a biomonitor, in order to know if the use of pesticides and fertilizers in paddy can enhance the Hg contamination to adjacent aquatic environment.MethodsSoil, suspended particulate matter and fish samples were sampled in a paddy field in South Brazil. A cold vapor system, coupled with a GBC 932 atomic absorption spectrophotometer was used for total Hg determinations in samples.ResultsThe paddy soil shows Hg concentration 2-fold higher (mean 31 ng g-1) in comparison to background areas (not cultivated). Suspended particle matter Hg concentration in paddy channels (mean 232.5 ± 44.2 ng g–1) are 1.5 times higher than the regional background. The analyzed fish specimens Astyanax sp in paddy showed Hg concentration 4-fold higher and significant different to background area. The mean Hg concentration in fish was: 51.7 ± 19.5 ng g–1 in Astyanax sp and 156.8 ± 44.0 ng g–1 in Corydoras paleatus.ConclusionsConsidering the linear regression and Man whitney test hypothesis to Hg concentration in fish tissue from paddy suggests that Astyanax sp. can be a good biomonitor of Hg contamination, whereas Corydoras paleatus is a potential biomonitor. However, more studies with Corydoras are necessary in order to aggregate consistency to this hypothesis.

CARACTERÍSTICAS HIDROLÓGICAS DE BAHÍA MAGDALENA, B.C.S. MÉXICO, EN EL PERÍODO 2001-2003

En el período de noviembre de 2001 a febrero de 2003 se realizaron seis muestreos en una red de 23 estaciones hidrográficas en Bahía Magdalena B.C.S., México, bajo diferentes amplitudes de marea, con el propósito de analizar la variación espacio temporal de temperatura superficial del mar (TSM), material particulado suspendido (MPS), concentración de clorofila a (Cla) y nutrientes inorgánicos disueltos (NID) Los resultados mostraron, al menos, dos épocas contrastantes en sus características físicas y químicas: 1) noviembre, mayo, julio y 2) enero, febrero. Los primeros presentaron generalmente marcados gradientes de TSM, MPS y NID de la boca al interior de la bahía asociados a altos índices de surgencia y en julio debido al efecto de alta irradiación y marea muerta. En la segunda época las características físicas y químicas fueron relativamente más homogéneas, con diferencias menores de 1ºC de TSM y menores concentraciones de MPS y NID, asociadas a bajos índices de surgencia y posiblemente otros aportes externos, así como mayor consumo de autótrofos. Se analiza la importancia de las condiciones físicas y químicas por época y por zonas, así como su posible papel en la ecología de este sistema. Hydrological characteristics of Bahía Magdalena, B.C.S., Mexico, during the period 2001-2003 From November 2001 to February 2003 we carried out six sampling field trips in Bahía Magdalena, Baja California Sur, Mexico, over a sampling net consisting of 23 hydrographic stations. Samples were obtained at different tide ranges in order to analyze time-space variations. Parameters analyzed were sea surface temperature (SST) suspended particle matter (SPM), Chlorophyll a (Chla) and dissolved inorganic nutrients (DIN). Results suggest at least two contrasting seasons, with different physical and chemical characteristics. One was during November - May - July, and the other was January – February. in the first period there were marked gradients of SST, SPM, and DIN,that increased inward the mouth of the lagoon, which was related to the upwelling index. In July, variations were associated to the effect of high solar irradiation and neap tides. During the second period, the physical and chemical characteristics were more homogeneous, and presented SST differences lower than 1ºC, and lower concentrations of SPM and DIN.Such condition was associated to the low upwelling index and other possible runoffs of water supplies, but also a higher consumption from autotrophic organisms. We analyzed the importance of physical and chemical characteristics importance for each period and by zone. We also discuss the role of these characteristics on the ecology of this ecosystem.