Hydrochemical Characterisation and Assessment of the Level of Contamination of Groundwater Collected by Private Waterworks in the Town of Moundou in the South of Chad

Groundwater is the main source of drinking water for large cities in most African countries. In Moundou, for example, the conventional groundwater supply system is failing. To compensate for this state failure, the population is building boreholes and wells, most of which tap the surface water table, generally referred to as the “water table”. The aim of this study is to characterize these waters in order to assess their level of contamination and, by extension, the degree of pollution of the water table. Major elements such as: Chloride (Cl-), Sulfate (SO42-), Nitrate (NO3-), Calcium (Ca2+), magnesium (Mg2+), sodium (Na+) and potassium (K+) were analysed by Liquid Chromatography and the Bicarbonate ion (HCO3-) was determined by the titrimetric method. The methodology applied is based on a combination of hydrochemical techniques and statistical analysis (PCA and CHA). A sampling campaign was carried out during high-water periods. The results of the physico-chemical analyses show mineralization ranging from 7.29 to 3670 μS/cm, with an average of 487.44 μS/cm. The groundwater studied is generally acidic, with a pH ranging from 3.26 to 6.41. Based on their anions, they are classified into four main hydrochemical facies: chloride and sulphate facies, calcium and magnesium facies, sodium and potassium facies and bicarbonate facies. The various correlations between major ions and statistical analyses have enabled us to identify three hydrogeochemical processes involved in water mineralization. The dominant process is silicate hydrolysis, followed by cation exchange, then anthropogenic input, which influences mineralization by polluting the water.

Experimental research on electric insulator damaged by chemical pollutant

As a main insulating device of power system, insulator can be damaged by chemical pollutant, which does threaten the electric system. An artificial pollution test system is utilized to study the damage mode for a suspension insulator, and the effects of concentration and existing state on damage efficiency of chemical pollutant are studied. Testing results show that the damage mode is flashover damage, whose efficiency increases with the decrease of creepage distance. The concentration of conductive particle of chemical pollution can effectively elevate damage efficiency, though it has a critical value. Unlike natural pollution, chemical pollutant can make insulator flashover damage whether in wet or dry condition. The damage process and relative results reveal the damage rule of insulator by chemical pollutant. Those studies put forward a new means to damage electric insulated device, and provide important reference to the protection design of electric insulator.

Responses of wheat seedlings to cadmium,mercury and trichlorobenzene stresses

The molecular response of wheat（Triticum aestivum L.,cv.Yangmai 13） seedlings to heavy metal（Cd,Hg） and 1,2,4-trichlorobenzene（TCB） stresses were examined by two-dimensional gel electrophoresis,image analysis,and peptide mass fingerprinting.The results showed inhibitions of root and shoot growth by Cd,Hg,and TCB.These stresses led to water deficit and lipid phosphorylation in the seedling which also promoted protein phophorylation in the leaves.Hg stress inhibited protein synthesis while Cd and TCB stresses induced or up-regulated more proteins in the leaves.Most of these induced proteins played important roles in the biochemical reactions involved in tolerance of wheat to Cd and TCB stresses.The primary functions of Cd-and TCB-induced proteins included methionine metabolism,Rubisco modification,protein phosphorylation regulation,protein configuration protection,H＋ transmembrane transportation and also the synthesis of ethylene,defense substances and cell wall compounds.

Chemical characteristics of PM_(2.5) during dust storms and air pollution events in Chengdu,China

Daily fine particulate （PM2.5） samples were collected in Chengdu from April 2009 to February 2010 to investigate their chemical profiles during dust storms （DSs） and several types of pollution events, including haze （HDs）, biomass burning （BBs）, and fireworks displays （FDs）. The highest PM2.5 mass concentrations were found during DSs （283.3 μg/m^3）, followed by FDs （212.7 μg/m^3）, HDs （187.3 μg/m^3 ）, and BBs （130.1 μ g/m^3）. The concentrations of most elements were elevated during DSs and pollution events, except for BBs. Secondary inorganic ions （NO3^- , SO4^2-, and NH4^＋） were enriched during HDs, while PM2.5 from BBs showed high K^＋ but low SO4^2- , FDs caused increases in K^＋ and enrichment in SO4^2-. Ca^2＋. was abundant in DS samples, Ion-balance calculations indicated that PM2.5 from HDs and FDs was more acidic than on normal days, but DS and BB particles were alkaline. The highest organic carbon （OC） concentration was 26.1 μg/m^3 during FDs, followed by BBs （23.6 μg/m^3 ）, HDs （19.6 μg/m^3 ）, and DSs （18.8 μg/m^3 ）. In contrast, elemental carbon （EC） concentration was more abundant during HDs （10.6μg/m^3） and FDs （9.5 μg/m^3） than during BBs （6.2μg/m^3） and DSs （6.0 μg/m^3）. The highest OC/EC ratios were obtained during BBs, with the lowest during HDs. SO4^2＋ /K^＋ and TCA/SO4^2- ratios proved to be effective indicators for differentiating pollution events. Mass balance showed that organic matter, SO4^2-, and NO3^- were the dominant chemical components during pollution events, while soil dust was dominant during DSs.

Laparoscopic treatment of a calcium fluorophosphate stone within a seminal vesicle cyst

Stones in the seminal vesicles are extremely rare. We present a 62-year-old patient with a stone within a seminal vesicle cyst, who was cured by laparoscopic treatment. The operative time was 80 rnin, and the estimated blood loss was 90 mL. Scanning electron microscope examination of the stone showed a compact crystal image externally and sparse spherical crystal structure in kernel. Composition of the stone was calcium fluorophosphate on X-ray diffractometer. The follow-up time was 15 months with no recurrence of cyst or stone. To our knowledge, this case is the first to describe laparoscopic removal of a stone within a seminal vesicle cyst, and the first to describe calcium fluorophosphate as the composition of seminal vesicle stones. （Asian JAndro12008 Mar; 10： 337-340）

Evaluation and Optimization of Electrode Configuration of Multi-Channel Corona Discharge Plasma for Dye-Containing Wastewater Treatment

A discharge plasma reactor with a point-to-plane structure was widely studied experimentally in wastewater treatment.In order to improve the utilization efficiency of active species and the energy efficiency of this kind of discharge plasma reactor during wastewater treatment,the electrode configuration of the point-to-plane corona discharge reactor was studied by evaluating the effects of discharge spacing and adjacent point distance on discharge power and discharge energy density,and then dye-containing wastewater decoloration experiments were conducted on the basis of the optimum electrode configuration.The experimental results of the discharge characteristics showed that high discharge power and discharge energy density were achieved when the ratio of discharge spacing to adjacent point distance（d/s） was 0.5.Reactive Brilliant Blue（RBB） wastewater treatment experiments presented that the highest RBB decoloration efficiency was observed at d/s of 0.5,which was consistent with the result obtained in the discharge characteristics experiments.In addition,the biodegradability of RBB wastewater was enhanced greatly after discharge plasma treatment under the optimum electrode configuration.RBB degradation processes were analyzed by GC-MS and IC,and the possible mechanism for RBB decoloration was also discussed.

An novel identification method of the environmental risk sources for surfacewater pollution accidents in chemical industrial parks

The chemical industry is a major source of various pollution accidents. Improving the management level of risk sources for pollution accidents has become an urgentdemand for most industrialized countries. In pollution accidents, the released chemicals harm the receptors to some extentdepending on their sensitivity or susceptibility. Therefore, identifying the potential risk sources from such a large number of chemical enterprises has become pressingly urgent. Based on the simulation of thewhole accident process, a novel and expandable identification method for risk sources causingwater pollution accidents is presented. The newlydeveloped approach, by analyzing and stimulating thewhole process of a pollution accident between sources and receptors, can be applied to identify risk sources, especially on the nationwide scale. Three major types of losses, such as social, economic and ecological losses,were normalized, analyzed and used for overall consequence modeling. A specific case study area, located in a chemical industry park （CIP） along the Yangtze River in Jiangsu Province, China,was selected to test the potential of the identification method. The results showed that therewere four risk sources for pollution accidents in this CIP. Aniline leakage in the HS Chemical Plantwould lead to the most serious impact on the surroundingwater environment. This potential accidentwould severelydamage the ecosystem up to3.8 kmdownstream of Yangtze River, and lead to pollution over adistance stretching to 73.7 kmdownstream. The proposed method is easily extended to the nationwide identification of potential risk sources.

Integrated Low-cost Wastewater Treatment for Reuse in Irrigation

For sustainable wastewater management in developing countries, the implementation of low\|cost, simple treatment systems should be encouraged. In this study, the performance of three treatment schemes was evaluated. The first step in all schemes was upflow anaerobic sludge blanket (UASB). The post treatment was either Algal Pond (AP). Lemna Pond (LP) or Rotating Biological Contactor (RBC). The results show that the performance of the UASB was satisfactory. Mean COD and BOD removal values were 78% and 85% respectively. The combination of UASB with an AP achieved significant improvement in the microbiological quality of the effluent. The geometric mean of fecal coliform in the effluent was 1.3×10 3 MPN/100ml. Residual COD was 143 mg O\-2/L. This relatively high value was due to the presence of algae in the AP effluent. The use of the LP as a post treatment achieved better quality effluent. As indicated by the physico\|chemical characteristics. However, fecal coliform removal was less by one log as compared to the AP effluent. When the RBC was used as a second stage. COD and BOD removal rates were 47% and 66% respectively. Also complete nitrification took place. Fecal coliform density declined by 5 logs.

Treatment and Reuse of Domestic Wastewater for Irrigation and Aquaculture Purposes

The feasibility of sewage treatment via combined chemical-biological techniques has been investigated. Two-stages pilot plant were designed for this purpose. The first stage was direct chemicalcoagulation-sedimentation using ferric chloride in-combination with lime to reduce the organic load and to remove the colloidal and suspended solids. A comparison of two separtion techniques namely chemical coagulation conventional sedimention and chemical coagulation tube settler sedimention were investigated. The second stage was either high rate oxidation pond or biological sand-bed to oxidize ammonia to nitrate. The results obtained showed that the effluent produced from the first stage is amaenable for restricted irrigation purposes. The HIROP proved to be satisfactory second treatment method for removal of pollutant. In addition high algal biomass was obtained. However, the use of sand-bed for nitrification proved to be more efficient, complete removal of ammonia was acheived.Average residual COD and BOD values were 66 and 38 mg O2/L, respectively. Fish toxicity was completely eleminated after the nitrification processes

Study on Migration and Transformation Rule of Organic Pollutants (COD) in Aerated Zone

Collecting waste water with a certain c onc entration of organic pollutants COD (chemical oxygen demand), static adsorption, static biodegradation and dynamic soil column experiments were made in laborato ry, we researched migration and transformation of COD in aerated zone, and put f orward a mathematical model showing the process. The results show that adsorptio n of organism in aerated zone is linear, which is represented by Henry's law s =K dc+s d, adsorption coefficient K d=0.069 3; biodegradati on diagram accord basically with first order kinetics equation c=c 0e -K 1t , biodegradation coefficient K 1 = 0.049 9 d -1 ; dispersio n coefficient D= 0.002 42 m 2/d in experiments. The migration and transform ation of organic pollutants (COD) in aerated zone jointly result from many f actors such as dispersion, adsorption and biodegradation etc..

Which metal represents the greatest risk to freshwater ecosystem in bohai region of china?

Metals discharged from industrial effluents,agricultural wastewater,and sewage runoff by rapid urbanization are of concern as contaminants of freshwater ecosystem because of their persistence and high toxicity to aquatic organisms.This study attempted to identify which metal posed the greatest risk to freshwater ecosystem in the Bohai Region,China.The metals arsenic(As),cadmium(Cd),chromium(Cr),copper(Cu),zinc(Zn),lead(Pb),nickel(Ni),mercury(Hg),iron(Fe),and manganese(Mn)were compared against norfloxacin and gamma-hexachlorocyclohexane(lindane).By comparing the median reported environmental and ecotoxicity concentrations,it showed that Cu,Fe,Zn,Mn,and Cr were the top five metals of concern.Of these,Cu was deemed to represent the highest risk and Hg the lowest risk.The risks for all metals were higher than those for norfloxacin and lindane.Almost all the metals except Hg had water concentrations that exceeded levels where ecotoxicity effects had been recorded in the literature.A comparison with the measurements across the UK rivers suggested that all metals examined had water concentrations about 5-to 10-fold higher than the UK median values except for Cu,Fe,Cd,and Pb.The Fuyang River,a tributary of the Haihe River Basin,seemed to be the location with the highest metal concentrations.However,comparing the post-2010 period to 2000-2009,concentrations of all the metals had fallen except for Fe and Mn,so risks have decreased over the last 7 yr with the greatest improvements for Cd and Pb.While metals still pose high risks to freshwater ecosystem in this region,there is encouragement that some control measures are taken into effect.

Bacillus amyloliquefaciens (IAE635) and their metabolites could purify pollutants, Vibrio spp. and coliformbacteria in coastal aquaculture wastewater

High-density aquaculture often causes the emission of polluted water to the marine environment in the coastal areas of China.To solve the aquaculture-related water quality problems,it is appropriate to adapt eco-friendly methods,such as using microbes and their metabolic products to purify polluted water.In this study,the purifying effects ofBacillus amyloliquefaciens(IAE635)metabolites(poly-γ-glutamic acid;PP)and IAE635 combined with their metabolites(MP)on turbidity,COD,NO3--N,NH4+-N,Vibrio spp.andcoliform bacteria in coastal aquaculture wastewater were conducted in the lab and in situ ponds.The results showed that the removal ofturbidity,COD,NH4+-Nand NO3--Nwith PP and MP was more significant(p<0.05).Compared to Control treatment(Co),the turbidity,COD,NH4+-Nand NO3--N concentrations at 24thhour were evidently reduced by 86.6%,87.5%,83.3%and 58.0%for PP,87.9%,93.5%,86.5%and 78.0%for MP,respectively.The populations of water pathogens under PP and MP were also significantly(p<0.05)removed compared with those of Co;at 24thhour,the Vibriospp.and coliform bacteria were decreased by 68.7%and 66.3%forPP,75.0%and 67.1%for MP,respectively.The water purifying effect of MP was slightly better than that of PP.In situ pond purification test demonstrated that MP significantly lowered the concentrations of turbidity,COD,NH4+-N,NO3--N and NO2--N,which was more effective than EM.A significantly higher(p<0.05)γ-PGA concentration and the total bacterial population for MP compared to PP indicatedthatMPpurifies the coastal aquaculture wastewaterby both flocculation and microbial decomposition.The application of MP will benefit the aquaculture industry by providing a novel method for the removal of chemical pollutants and pathogens.