Pearl River Water Research Articles

Fast and highly efficient tetracyclines removal from environmental waters by graphene oxide functionalized magnetic particles

The extensive use of tetracycline antibiotics (TCs) has caused a lot of environmental pollution. In our study, graphene oxide functionalized magnetic particles (GO-MPs) were prepared and utilized as adsorbents for removing four TCs including tetracycline, oxytetracycline, chlortetracycline, and doxycycline from aqueous solution. The adsorption process is fast and highly efficient. The factors (contact time, volume of TC solution, solution pH and ionic strength) affecting the adsorption process were studied. Solution pH and ionic strength had insignificant effects on TC adsorption. The maximum adsorption capacity for TC was calculated to be 39.1mgg−1 according to the Langmuir adsorption isotherm. The adsorption of GO-MPs for TCs was attributed to the strong π–π interaction. The GO-MPs were applied for removing TCs from mineral water and the Pearl River water. GO-MPs demonstrated highly efficient removing performance for low levels of TCs in large volume of water sample solutions.

Monitoring and Analyzing Water Pollution of the Pearl River in Guangzhou Section by Using Remote Sensing Images and Field Acquisition Data

Water quality of the Pearl River had been severely polluted in recent years due to the lots of discharges which were mostly including with untreated industrial wastewater and urban sewage and so on. So, this paper paid its’ attention to monitoring water pollution of the Pearl River in Guangzhou and tried to establish the model of predicting about water by using remote sensing and field acquisition data in order to analysis the relationship of water quality and TM DN data. In this paper, the Guangzhou section of Pearl River was selected and its’ 9 sections were monitored as based data of water pollution in order to established the multivariate regression model. The results of this research showed that the monitoring data of remote sensing could present the pollution condition of Pearl River's water. At the same time, remote sensing also was one of the fast and effective methods to show the macroscopic view to understand the degree of water quality of any district in the developing counties.

Selectivity of two types of sulfadimidine‐imprinted monolithic polymer‐based fibers

Molecularly imprinted polymeric monolithic fiber is a new technique of solid-phase microextraction that focuses on selectivity. However, the inner mechanism of increasing the selectivity is not well understood. Here, a new approach to improve the selectivity is shown through controlling the surface of a molecular imprinted polymeric monolithic fiber. Sulfadimidine-imprinted polymeric monolithic fibers were fabricated using two kinds of molds, the polytetrafluoroethylene capillary and the silica capillary. A mixture of sulfadimidine, sulfamerazine, sulfadiazine, and sulfametoxypirydazine was used to test the selectivity of the fibers to sulfadimidine. This paper demonstrates that the extraction ratio for sulfadimidine in mixture is increased to more than 150% in sulfadimidine-imprinted polymeric monolithic fiber compared to nonimprinted polymeric monolithic fiber. The extraction ratio is increased to about 30% in sulfadimidine-imprinted polymeric monolithic fiber fabricated from silica capillary than in the counterpart from nonimprinted polymeric monolithic fiber. The sulfadimidine-imprinted polymeric monolithic fibers were also applied to extract standard mixtures spiked into Pearl River water and milk. The results indicated that polytetrafluoroethylene-sulfadimidine imprinted polymeric monolithic fiber showed highest selectivity to sulfadimidine in complex samples.

Longitudinal Transportation Mechanism of Sallinity in West Channel of Lingding Bay in Dry Season, China

Estuary is the transition zone,where fresh water and salty water mixes strongly.In dry season,because Discharge of the Pearl River water decreases,salt water intrusion become serious in the Pearl River delta,and affect the safety of fresh water supply.So,salinity transport mechanism is a very important topic.In this paper,according to the measured data in November 3-4,2005,calculate and analyze the longitudinal flow characteristics,salinity distribution and transport mechanisms. Research results show that the velocity varieties with ebb and flood processes,the surface velocity is larger than that of bottom and middle layer.In ebb slack and flood slack period,there is a zero velocity point,and its movement distance is up to 10km.Vertical residual circulation is obvious, surface layer is to sea,and bottom layer is to land.Net salinity transport direction is from sea to land.salinity vertical stratification is evident,and varieties obviously with tide changes.Surface salinity gradient is larger In flood period,and bottom salinity gradient is larger in ebb period.In ebb slack time,salinity is vertical uniform distribution.

Preparation of multi-walled carbon nanotubes functionalized magnetic particles by sol–gel technology and its application in extraction of estrogens

Magnetic silica particles coated with hydroxy-terminated multi-walled carbon nanotubes (MWCNTs–OH) were prepared by sol–gel technology, characterized and used for the convenient, rapid and efficient extraction of several estrogens (including diethylstilbestrol, estrone and estriol) in water followed by sweeping micellar electrokinetic chromatography analysis with UV detection. The results demonstrated that sol–gel technology was a feasible, simple and effective technique for the preparation of MWCNTs–OH functionalized magnetic silica particles. The factors affecting the extraction efficiency of estrogens (the pre-activation of magnetic particles, adsorption time, desorption time and the amount of elution solvent) were carefully investigated. The extraction efficiencies for diethylstilbestrol, estrone and estriol were 95.9%, 93.9%, and 52.4%, respectively, under the optimum conditions. The method detection limits for the three estrogens were less than 0.2 ng mL −1. The developed method was applied for the analysis of tap water, mineral water, Pearl River water and honey.

Distribution, regional sources and deposition fluxes of organochlorine pesticides in precipitation in Guangzhou, South China

We analyzed rainwater collected from multiple sites, Guangzhou, China, from March to August 2005, with the aim to characterize the distribution, regional sources and deposition fluxes of organochlorine pesticides (OCPs) in South China. Eight species of organochlorine pesticide were detected, including hexachlorocyclohexanes (HCHs), dichlorodiphenyltrichloroethanes (DDTs), and endosulfans. Volume-weighted mean monthly total concentrations varied from 3.65 ± 0.95 to 9.37 ± 2.63 ng L − 1 , and the estimated total wet deposition flux was about 11.43 ± 3.27 µg m − 2 during the monitoring period. Pesticides were mainly detected in the dissolved phase. Distribution coefficients between particulate and dissolved phases in March and April were generally higher than in other months. HCHs, p,p′-DDD and p,p′-DDT in precipitation were attributed to both the residues and present usage of insecticides in Pearl River Delta. The concentrations of p,p′-DDD + p,p′-DDT were relatively high from April to August, which were related to the usage of antifouling paints containing DDT for fishing ships in seaports of the South China Sea in summer. In contrast, endosulfans were relatively high in March, which was related to their seasonal atmospheric transport from cotton fields in eastern China by the Asian winter monsoon. The consistency of the variation of endosulfans, p,p′-DDD and p,p′-DDT concentrations with the alternation of summer and winter monsoon suggested that the Asian monsoon played an important role in the long-range transport of OCPs. In addition, the wet deposition of OCPs may influence not only Pearl River water but also the surface land distributions of pesticides in the Guangzhou area, especially for endosulfans, p,p′-DDD and p,p′-DDT.

An overview of water resources management of the Pearl River

This paper summarizes the main features of water resources management of the Pearl River basin in southern China. A regulation over the basin through integrating various regions was first established for enhancing the water resources management. Based on such a regulation, a public policy frame was then constructed aiming for the harmony between human activities and nature. It is hoped that, as a result, the basin's socio-economic sustainable development could be achieved. In practice, the Pearl River Water Resources Commission (PRWRC), which is the basin regulatory authority, has been focusing on various aspects of regulating water basin and conserving water resources. These aspects include the development of innovative regulations of treating water, exploration of compensation schemes for water resources prevention, investigation of the hydraulic engineering project impacts on region relocation and ecology, and establishment of marketing schemes for sustainable application of water resources. It is expected that these regulating water resources aspects would result in enhancing public participation and negotiation in the Pearl River basin management. A case study is presented on the PRWRC's effort in coordinating water discharges from a number of reservoirs to protect the safe water supply in the Pearl River basin from seawater intrusion during the dry season.

The Seasonality of Fecal Coliform Bacteria Pollution and its Influence on Closures of Shellfish Harvesting Areas in Mississippi Sound

Runoff from agricultural lands and farm animal feedlots is one of the major sources of fecal coliforms in surface waters, and fecal coliform (FC) bacteria concentrations tend to vary with season because of seasonal variations in climatic factors. However, El Niño--Southern Oscillation (ENSO) events may affect the extent and patterns of seasonality in FC levels in coastal waters. Water quality monitoring data for shellfish management collected during El Niño (1990, 1992, 1997), and La Niña (1999, 2000) years were analyzed to evaluate the extent to which these events influenced Pearl River stage, and bacterial levels, water temperature, and salinity in the western part of Mississippi Sound. Models to predict FC levels in relation to various environmental factors were also developed. In 1990, 1992 and 1997, FC geometric mean counts peaked in late winter (January/February) reaching 120 MPN (February 1990), 165 MPN (January 1992), and 86 MPN (January 1997), and then decreased considerably during spring and summer (1.2 - 19 MPN). Thereafter, FC abundance increased slightly in fall and early winter (1.9 - 24 MPN). Fecal coliform abundance during the 2000 La Niña year was much lower (1.0 -10.3 MPN) than in 1992 (1.2 - 165 MPN), and showed no seasonal pattern from January to August, perhaps due to the relative scarcity of rainfall in 2000. In 1995 (ENSO neutral year), peak geometric mean FC count (46 MPN) was lower than during El Niño years and occurred in early spring (March). The seasonal and between year variations in FC levels determined the number of days during which the conditionally approved shellfish growing area was opened for harvesting shellfish. For example, from January to April 1997, the area was not opened for shellfish harvesting, whereas in 2000, the number of days during which the area was opened ranged from 6 - 27 (January to April) to 24 - 26 (October to December). ENSO events thus influenced the extent and timing of the peak levels of fecal coliforms in Mississippi Sound. Models consisting of one or more of the variables: Pearl River stage, water temperature, and salinity were developed to predict FC concentrations in the Sound. The model parameter(s) explained 56 to 91% of the variations in FC counts. Management of shellfish in Mississippi Sound can be improved by utilizing information on the forecasted three to seven years occurrence of ENSO events. In addition, since Pearl River stage was the most important variable predicting FC concentration in the Sound, a study of the levels and sources of FC bacteria in the river, especially the middle and lower sections, is needed for developing a management plan for reducing FC bacteria pollution in the Sound.

Influence of inter-annual variations in climatic factors on fecal coliform levels in Mississippi Sound

Information on the effects of inter-annual variations in climatic factors on fecal coliform levels in coastal waters is scarce. We used 11 years (1990-2001) of rainfall, water temperature, Pearl River stage and salinity data to assess the effects of the 1991-1992 and 1997-1998 El Nino events on fecal coliform levels in Mississippi Sound. El Nino-Southern Oscillation had major effects on Pearl River stage and water quality in the Sound. The geometric mean fecal coliform number differed among years (P = 0.0001), being highest during 1991-1992 El Nino years (14.22 MPN per 100 ml) and lowest during 1999-2000 La Nina years (<1.8 MPN per 100 ml). Mean salinity varied among years (P = 0.0001) from 9 ppt (1991-1992) to 21 ppt (1999-2000). Mean water temperature was lowest in 1997-1998 (14.5 degrees C) and highest in 1998-2000 (19.4 degrees C). Pearl River stage differed among years (P = 0.0001), ranging from 1.96 m (1999-2000) to 3.57 m (1997-1998). Inverse relationships were observed between fecal coliform levels and salinity (r(2) = 0.74; P = 0.001) and water temperature (r(2) = 0.69; P=0.001), whereas positive relationships were obtained with total rainfall (r(2) = 0.52; P = 0.013) and Pearl River stage (r(2) = 0.90; P = 0.0001). These relationships are useful for evaluating the potential effects of climate change on water quality and classification of shellfish growing waters in order to protect humans from consuming contaminated shellfish in shallow river-influenced estuaries.