Colloidal toxic trace metals in urban riverine and estuarine waters of Yantai City, southern coast of North Yellow Sea

Trace Metal Partitioning in the Salinity Gradient of the Highly Stratified Estuary: A Case Study in the Krka River Estuary (Croatia)

“…Six sampling campaigns were conducted in the Krka River estuary (Croatia) located in front of Šibenik town (N 43 24 July and 20 September 2020; 7 April 2021. Samples of the vertical column profile were collected by a 'butterfly'-type vertical water sampler or van Dorn-type horizontal sampler (alfa or beta, Wildco) at 6 depths (M1-M6), selected according to the measured vertical salinity profiles (using the EXO2 multiparameter CTD probe, YSI, Yellow Springs, USA) and the total water column depth: M1 and M2 in FWL, M3 and M4 in FSI, M5 and M6 in SWL.…”

“…The measured trace metal concentrations in the unfiltered samples represent acidleachable (quasi-total) metal concentrations, and within the text, they are referred to as total metal concentrations. Particulate and dissolved fractions are usually separated using 0.2 µm pore size filters, and for the separation of colloidal and truly dissolved fractions, membranes of nominal weight between 1-10 kDa are most frequently used [6,21,22,24,37].…”

“…Colloids can be isolated by a variety of physicochemical techniques such as ultrafiltration, dialysis, gel techniques, field flow fractionation and capillary electrophoresis [6,[18][19][20][21][22]. Among them, a low-cost and easily implemented technique, centrifugal ultrafiltration, is considered to be a high-efficiency colloidal substance separation technology [23,24].…”

Potential for colloid removal from petrochemical secondary effluent by coagulation–flocculation coupled with persulfate process

“…49,50 The chemical interaction of the small-molecule colloids in the CF process suggested stronger aromaticity resulting in a slight increase in UV absorption at 254 nm for the low-MW organics. 22 For the PS process, the removal contributions as measured by the UV 254 absorption intensity for all MW fractions were 33.0-100.0%. The significant decrease in all MW fractions is due to structural changes by seizing electrons on the aromatic organics and attacking unsaturated bonds via the strong oxidation of SO 4 ˙−.…”

“…With the development of ultrafiltration technology, ultrafiltration membranes with different molecular weight (MW) cut-offs have been used for distributing colloids. 21,22 Recently, colloidal chemical species, which can refer to the fraction 3 K-0.45 μm or 1 K-0.45 μm, have been reported in the literature; a 1 K MW cut-off corresponds to a membrane pore size of about 1.3 nm. Therefore, the soluble matter is divided into three groups based on particle size: the particulate (>0.45 μm), colloidal (3 K-0.45 μm or 1 K-0.45 μm), and truly dissolved (<1 K) phases.…”