Adsorption and Desorption Characteristics of Cadmium and Lead in Typical Paddy Soils of Jiangxi Province and Its Environmental Risk Assessment

[Objective] This study aimed to investigate the adsorption and desorption characteristics of cadmium and lead in typical paddy soils of Jiangxi Province. [Method] Gleyed paddy soil and waterloggogenic paddy soil were collected from Jiangxi Province and used as experimental materials to investigate single and com- petitive adsorption and desorption behaviors of cadmium and lead by batch equilib- rium method. The environmental risk of the presence of cadmium and lead in paddy soils was assessed using distribution coefficients. [Result] Under equal ratio condi- tions, the adsorption capacity of lead by two types of paddy soils was higher than that of cadmium, and the adsorption rate in waterloggogenic paddy soil was higher than that in gleyed paddy soil. The desorption capacity of cadmium by two types of paddy soils was higher than that of lead, and the desorption rate in gleyed paddy soil was higher than that in waterloggogenic paddy soil. Under competitive condi- tions, the adsorption capacity of cadmium and lead by paddy soils was significantly reduced compared with single ion system, while the desorption rate was remarkably improved. The potential environmental risk of cadmium contamination was greater than that of lead in paddy soils. Moreover, environmental risks of cadmium and lead were reduced with the increase of pH, which increased significantly under the coex- istence state. [Conclusion] In the coexistence of cadmium and lead, cadmium con- tamination should be controlled and avoided compared with lead contamination in paddy soils.

Distribution, Chemical Speciation, and Environmental Risk Assessment of Heavy Metals in Tailings Soils near Dexing Copper Mine, China

To complement information of heavy metals＇ distribution, chemical speciation, activity and environmental risks in agricultural soils surrounding tailings, a total of 16 samples obtained from the 4 # railings site of Dexing copper mine of China were investigated. The total concentrations of heavy metals Zn, Fe, Cu, Pb, Cd, Cr, Hg, As, Mn, Ag, Co, and Ni were determined by inductively coupled plasma-atomic emission spectrometry. Chemical speciations of Cu, Cd, and Zn were investigated with the procedures recommended by Tessier（1979）. Two different assessment approaches （GB 15618- 1995 and risk assessment code, RAC ） were employed to estimate heavy metals＇ environmental risks. Results indicated that heavy metals, especially Cu and Cd were in high levels of accumulation in these samples. Chemical speciation analysis results revealed that Cu was mainly in organic matter bound fraction （ORG） and residual fraction （ RES）, and Cd was predominantly in exchangeable fraction （EXC）, while Zn appeared mainly with the RES fraction. Environmental risk analysis results showed that Cd was in ＂heavy＂ pollution level （ classification m ） in almost all samples, which may exert ＂high＂ or ＂very high＂ environmental risks. Whereas, for Cu, one fourth samples showed ＂heavy＂ pollution level, but were located in ＂low＂ or ＂medium＂ environmental risk ranks. For Zn, many samples were grouped in ＂light＂ pollution level （ classification II ）, but were related to ＂ medium＂ and ＂ high＂ environmental risk ranks. These results indicated heavy pollution and high environmental risk of Cd in soils surrounding the 4# tailings site, which should be paid more attention to. Meanwhile, for Cu and Zn, the contrary results obtained by different environmental risk assessment approaches, may suggest that a more scientific, adequate environmental risk assessment criterion should consider both total content and chemical speciation activity of heavy metals.

Modeling the fate of paddy field pesticide in surface water and environmental risk assessment

The risk of drinking water is greatly concerned because of the large amount of pesticide applied to paddy field and the contamination of drinking water sources due to the runoff. A mathematical model is developed, based on the mass balance, to predict the fate of paddy field pesticides from application, runoff and mixing in a river, taking account of the physical chemical properties and processes of volatilization, degradation, adsorption and desorption. The model is applied to a river basin in Japan to estimate the contaminant level of several popularly used pesticides at the water intakes. The health risk in drinking water induced by each pesticide concerned is estimated and evaluated by comparing with the acceptable daily intake values(ADI) and with that induced by trihalomethanes. An index to evaluate the total risk of all pesticides appearing in water is proposed. The methods for risk management are also discussed.

Environmental Risk Assessment of Chemical Projects——A Case Study of a Polystyrene Production Project

Taking a polystyrene production project as an example, according to Technical Guidelines for Environmental Risk Assessment of Con- struction Projects （HJ/T169-2004）, we firstly identity the risk of substances and production process to determine the major source of danger, and then conduct source analysis and consequence prediction of the maximum credible accident, finally assess the environmental risk of the project and propose main risk management measures. The results reveal that the environmental risk of the project is acceptable, and it is suggested that some dsk prevention and mitigation measures as well as contingency plans should be established.

Thoughts of a travelling ecologist 14. Structure-function conflation in environmental risk assessment and monitoring

Recently,I attended a conference organised by the European Food Safety Authority in the beautiful and prosperous Italian city of Parma.The overall topic of the conference was risk assessment,and the program included a section on aspects of environmental risk assessment.In various areas,including the evalution of the effects of pesticide applications,invasive organisms or genetically modified plants(Arpaia et al.,2014)preparing an environmental risk assessment is an obviously relevant exercise.

Significance of adverse outcome pathways in biomarker-based environmental risk assessment in aquatic organisms

In environmental risk assessments（ERA）, biomarkers have been widely used as an early warning signal of environmental contamination. However, biomarker responses have limitation due to its low relevance to adverse outcomes（e.g., fluctuations in community structure, decreases in population size, and other similar ecobiologically relevant indicators of community structure and function）. To mitigate these limitations, the concept of adverse outcome pathways（AOPs） was developed. An AOP is an analytical, sequentially progressive pathway that links a molecular initiating event（MIE） to an adverse outcome. Recently, AOPs have been recognized as a potential informational tool by which the implications of molecular biomarkers in ERA can be better understood. To demonstrate the utility of AOPs in biomarker-based ERA, here we discuss a series of three different biological repercussions caused by exposure to benzo（a）pyrene（Ba P）, silver nanoparticles（Ag NPs）, and selenium（Se）. Using mainly aquatic invertebrates and selected vertebrates as model species, we focus on the development of the AOP concept. Aquatic organisms are suitable bioindicator species whose entire lifespans can be observed over a short period; moreover, these species can be studied on the molecular and population levels.Also, interspecific differences between aquatic organisms are important to consider in an AOP framework, since these differences are an integral part of the natural environment.The development of an environmental pollutant-mediated AOP may enable a better understanding of the effects of environmental pollutants in different scenarios in the diverse community of an ecosystem.

Environmental Risk Assessment for Exploration and Extraction Processes of Unconventional Hydrocarbon Deposits of Shale Gas and Tight Gas:Pomeranian and Carpathian Region Case Study as Largest Onshore Oilfields

Shale gas and tight gas exploration and extraction processes create potential threats to the environment.In Poland,no comprehensive guidelines for environmental risk assessment have been prepared so far.This paper presents a proposal of environmental risk assessment methodology which can be used for corporate risk management procedures during exploration and extraction of unconventional hydrocarbons in Poland.The most frequent environmental threats that may occur during the exploration and exploitation of unconventional hydrocarbon deposits include degradation of soils through construction of drilling rigs and access roads,landforms change,local soil pollution caused by fuels,cleaning agents and materials used to prepare drilling fluids,rubble,cement,gravel,pollution of surface and underground water as a result of emergency discharges of sewage,infiltration of pollution from waste reservoirs,disturbance of hydrogeological equilibrium through significant water intake,noise and atmospheric pollution resulting from the combustion of fuels.To check the level of these threats' six exploration sites form Pomeranian and Carpathian region of Poland(3 wells of shale gas and 3 wells of tight gas) have been evaluated in detail,and the risk quantification has been made.Because of a local,short-term and reversible environment impact,the environmental risks for the exploration and extraction processes of unconventional hydrocarbons have been found to be medium or negligibly small.It is recommended that using the same methodology for other regions of Poland where we can find unconventional hydrocarbons and it can be enriched in dedicated application with spatial maps to give the investors a quick feedback on the potential environmental risks.

Occurrence,spatial and seasonal variation,and environmental risk of pharmaceutically active compounds in the Pearl River basin,South China

The occurrence,fate,and environmental risk of 40 pharmaceutically active compounds(PhACs)from surface waters and sediments were comprehensively investigated in the Beijiang River,Xijiang River,and Maozhou River of the Pearl River basin,South China.Salicylic acid and diclofenac(antiinflammatory drugs),gemfibrozil(a lipid regulator),carbamazepine(an antiepileptic drug),diazepam(a psychoactive drug),and 2-methyl-4-chloro-phenoxyacetic acid(MCPA,a pesticide)were the most ubiquitous compounds in the studied region.The average concentrations of detected PhACs in surface waters and sediments ranged from 0.17 to 19.1 ng/L and 0.10 to 10.4 ng/g,respectively.Meanwhile,PhACs concentration in surface waters and sediments varied greatly among and within the Beijiang River,Xijiang River,and Maozhou River.The largest annual flux of PhACs of the Xijiang River and Beijiang River was more than 11000 kg per annum,whereas only 25.7 kg/a in the Maozhou River.In addition,the estimated emissions of PhACs in the Beijiang River,Xijiang River,and Maozhou River ranged respectively from 0.28 to 4.22 kg/a,0.12 to 6.72 kg/a,and 6.66 to 91.0 kg/a,and the backestimated usage varied with a range from 12.0 to 293 kg/a,6.79 to 944 kg/a,368 to 17459 kg/a.Moreover,the emissions of PhACs showed a close relationship with the gross domestic product(GDP)of each city along the Pearl River.The environmental risk assessment suggested that diazepam and ibuprofen had a moderate risk in this region.

Current situation and forecast of environmental risks of a typical lead-zinc sulfide tailings impoundment based on its geochemical characteristics

The potential environmental implications of a Pb(Lead)-Zn(Zinc)sulfide tailing impoundment were found to be dependent on its geochemical characteristics.One typical lead-zinc sulfide tailing impoundment was studied.Ten boreholes were set with the grid method and 36 tailings were sampled and tested.According to the results of metal content analysis,the tailing samples contained considerably high contents of heavy metals,ranging from 6.99 to 89.0 mg/kg for Cd,75.3 to 602 mg/kg for Cu,0.53%to 2.63%for Pb and 0.30%to 2.54%for Zn.Most of the heavy metals in the sample matrix showed a uniform concentration distribution,except Cd.Cd,Pb,Zn,and Mn were associated with each other,and were considered to be the dominant contributors based on hierarchical cluster analysis.XRD,SEM and XPS were employed for evaluation of the tailing weathering characteristics,confirming that the tailings had undergone intensive weathering.The maximum potential acidity of the tailings reached 244 kg H2SO4/ton;furthermore,the bioavailability of heavy metals like Pb,Cd,Cr,Cu,and Zn was 37.8%,12.9%,12.2%,5.95%,and 5.46%respectively.These metals would be potentially released into drainage by the weathering process.Analysis of a gastrointestinal model showed that Pb,Cr,Ni and Cu contained in the tailings were high-risk metals.Thus,control of the heavy metals’migration and their environmental risks should be planned from the perspective of geochemistry.

Wood Preservative Solutions for Creative and Sustainable Bridge Design and Construction

Timber bridges can provide an economical alternative to concrete and steel structures, particularly in rural areas where vehicle traffic is light to moderate. The wooden components of bridges have historically been preserved with either an oil type or waterborne preservative system to protect the wood from decay in order to maintain required performance standards for an extended period of time. The focus of this paper is to describe some of the key preservatives, research and case studies that support use of preserved wood, and some important steps to follow for the appropriate and safe use of preserved wood when the planned application will be in or over aquatic and wetland environments. A wealth of scientific information has been collected and analyzed that clearly suggests the use of preserved wood does not present a significant adverse effect on aquatic and wetland environments. This conclusion is based on two decades of empirical research and case study evaluating the environmental fate and effects of preserved wood, level of migration of contaminates into aquatic and marine environments, and the preserved wood environment. This is particularly true when risks are properly assessed on a project site, the appropriate preservative is selected and the wood is preserved to the Western Wood Preservers Institute＇s BMPs （best management practices）, along with properly installing and maintaining the preserved material. To assist with the assessment process, peer-reviewed risk assessment models for 11 commonly used preservatives have been developed that provide for streamlined data entry by users and allow for evaluation of a structure above and below water. A companion preliminary screening level assessment tool is also available. When these measures are properly utilized engineers, biologists and other responsible officials can be confident that the service life of the preserved wood components will more than likely meet the required performance standards in an environmentally safe manner for up to 50 or more years on a majority of timber bridge projects.

Spatial–temporal distribution and potential ecological risk assessment of nonylphenol and octylphenol in riverine outlets of Pearl River Delta, China

The aquatic environments of the Pearl River Delta in Southern China are subjected to contamination with various industrial chemicals from local industries. In this paper, the occurrence, seasonal variation and spatial distribution of alkylphenol octylphenol （OP） and nonylphenol （NP） in fiver surface water and sediments in the runoff outlets of the Pearl River Delta were investigated. NP and OP were detected in all water and sediment samples and their mean concentrations in surface water during the dry season ranged from 810 to 3366 ng/L and 85.5 to 581 ng/L, respectively, and those in sediments ranged from 14.2 to 95.2 ng/g dw and 0.4 to 3.0 ng/g dw, respectively. In surface water, much higher concentrations were detected in the dry season than those in the wet season. In sediments, the concentrations in the dry season were also mostly higher. High concentrations of NP and OP were found in Humen outlet, likely due to high levels of domestic and industrial wastewater discharges. An ecological risk assessment with the use of hazard quotient （HQ） was also carried out and the HQvalues ranged from 3.6 × 10^-5 to 35 and 64% of samples gave a HQ 〉 1, indicating that the current levels of NP and OP pose a significant risk to the relevant aquatic organisms in the region.

Development of environmental management system in China’s financial sector

The establishment of the environmental management system in the financial sector can be effectively promoted through the introduction of the environmental protection concept and its implementation by the financial sector.The impact of a sustainable development system on the sector is analyzed in this article from three aspects:environmental risk assessment,financing support for environmental protection projects,and financial services to environmentally friendly corporations and individuals.Influential factors on the development of the environmental management system in China’s financial sector are discussed from the perspective of various entities such as financial institutions,financial regulation authorities,environmental protection departments,corporations,and the public.It is pointed out that China’s financial sector is now in the transitional phase from a defensive attitude to a preventive attitude.Strengthening governmental guidance,the supervision of regulators as well as public awareness of environmental protection should be used to enhance the initiative in the development of the environmental management system in the Chinese financial sector.

Assessment of popular techniques for co-processing municipal solid waste in Chinese cement kilns

Cement kiln co-processing techniques have been developed in the past 20 years in China,and more than 60 factories now use fermentation,screening,and gasification pre-treatment techniques to coprocess municipal solid waste(MSW).There three complete MSW pre-treatment techniques,coprocessing procedures,and environmental risk assessments have been described in few publications.In this study,we assessed the effectiveness of each technique.The results suggested that the pollutant content released by each pre-treatment technology was lower than the emission standard.To reveal the mechanisms of pollutant migration and enrichment,the substances in the kiln and kiln products are investigated.The input of co-processing materials(Co-M)produced by fermentation caused formation of polychlorinated dibenzo-p-dioxins and dibenzoftiran(PCDD/Fs)in the bypass flue gas(By-gas)in excess of the regulatory standard.The Co-M input produced by the screening and gasifier technologies caused the total organic carbon(TOC)concentration to exceed the standard.In addition,the NOx,TOC,and PCDD/Fs in the By-gas exceeded the regulatory standard.Raw meal was the primary chlorine and heavy metals input stream,and clinker(CK)and cement kiln dust(CKD)accounted for>90%of the total chlorine output stream.Flue gas and CKD were the primary volatile heavy metal(Hg)output streams.Greater than 70%of the semi-volatile heavy metals(Cd,Pb,T1 and Se)distributed in hot raw meal and bypass cement kiln dust.The low-volatility heavy metals were concentrated in the CK.These results indicated that co-processing techniques used in China still require improvement.

Distribution of chlorpyrifos in rice paddy environment and its potential dietary risk

Chlorpyrifos is one of the most extensively used insecticides in China. The distribution and residues of chlorpyrifos in a paddy environment were characterized under field and laboratory conditions. The half-lives of chlorpyrifos in the two conditions were 0.9–3.8 days（field） and 2.8–10.3 days（laboratory）, respectively. The initial distribution of chlorpyrifos followed the increasing order of water 〈 straw 〈 soil, and soil was characterized as the major absorber. The ultimate residues in rice grain were below the maximum residue limit（MRL） with a harvest interval of 14 days. The chronic exposure for chlorpyrifos was rather low compared to the acceptable daily intake（ADI = 0.01 mg/kg bw） due to rice consumption. The chronic exposure risk from chlorpyrifos in rice grain was 5.90% and 1.30% ADI from field and laboratory results respectively. Concerning the acute dietary exposure,intake estimated for the highest chlorpyrifos level did not exceed the acute reference dose（ARf D = 0.1 mg/kg bw）. The estimated short-term intakes（ESTIs） were 0.78% and 0.25% of the ARf D for chlorpyrifos. The results showed that the use of chlorpyrifos in rice paddies was fairly safe for consumption of rice grain by consumers.

Prey-mediated effects of mCry51Aa2-producing cotton on the predatory nontarget bug Orius majusculus(Reuter)

Genetically engineered(GE)cotton,MON 88702,is protected against cer-tain sucking pests,such as plant bugs and thrips,by producing mCry51Aa2,a mod-ified protein from Bacillus thuringiensis(Bt).Predatory pirate bugs(Orius spp.),natural enemies contributing to biological pest control,are also sensitive to the insecti-cidal protein when exposed continuously to high concentrations.We evaluated effects of MON 88702 on Orius majusculus when fed prey types with different mCry51Aa2 concen-trations.When neonates were provided exclusively Tetranychus urticae spider mites reared on MON 88702(high mCry51Aa2 content),adverse effects on predator survival and de-velopment were confirmed,compared with specimens fed prey from near-isogenic non-Bt cotton.When fed a mixture of T.urticae and Ephestia kuehniella eggs(mCry51Aa2-free),predator life table parameters were similar to the treatment where eggs were fed exclu-sively.When mCry51Aa2-containing spider mites were provided for a limited time at the beginning or the end of juvenile development,effects were less pronounced.While pirate bug nymphs showed similar consumption rates for prey from Bt and non-Bt cotton,choice experiments revealed a preference for E.kuehniella eggs over spider mites.Lepidopteran larvae(Spodoptera littoralis,high mCry51Aa2 content)or cotton aphids(Aphis gossypii,mCry51Aa2-free)reared on MON 88702 as alternative prey did not result in adverse ef-fects on O.majusculus.Our study suggests limited risk of mCry51Aa2-producing cotton for O.majusculus,because its sensitivity for the Bt protein is relatively low and its natural food consists of diverse prey species with varying concentrations of Bt protein.

Tier-1 assays for assessing the toxicity of insecticidal proteins produced by genetically engineered plants to non-target arthropods

In assessing an insect-resistant genetically engineered （IRGE） crop before its commercialization, researchers normally use so-called ＂Tier-1 assays＂ as the initial step to determine the effects of the crop on non-target organisms. In these tests, the insecticidal proteins （IPs） produced by the IRGEs are added to the diets of test organisms in the laboratory. Test organisms in such assays can be directly exposed to much higher concentrations of the test IPs than they would encounter in the field. The results of Tier-1 assays are thus more conservative than those generated in studies in which the organisms are exposed to the IPs by feeding on IRGE plant tissue or in the case of predators or parasites, by feeding on invertebrate prey or hosts that have fed on IRGE plant tissue. In this report, we consider three important factors that must be considered in Tier-1 assays： （i） methods for delivery of the IP to the test organisms; （ii） the need for and selection of compounds used as positive controls; and （iii） methods for monitoring the concentration, stability and bioactivity of the IP during the assay. We also analyze the existing data from Tier-1 assays regarding the toxicity of Bt Cry proteins to non-target arthropod species. The data indicate that the widely used Bt proteins have no direct toxicity to non-target organisms

Bioavailability of Arsenic and Antimony in Terrestrial Ecosystems:A Review

Arsenic (As) and antimony (Sb) are metalloids that belong to group 15 of the periodic table and exhibit toxic properties in the environment. They mostly occur naturally at low concentrations in soil, although these can be significantly elevated in both aquatic and terrestrial food chains as a result of dispersion from anthropogenic sources, e.g ., mining activities. The bioavailability, i.e., the proportion of the contaminant in soil and dust that is available for uptake by plants and other living organisms, presents the greatest risk to terrestrial ecosystems. Various in vivo and in vitro methods have been used to measure As and Sb bioaccessibility in soil and dust. In vivo measurement of bioavailability can be time consuming, expensive, and unethical;thus, in vitro methods are commonly preferred. However, there is considerable uncertainty around the efficacy of in vitro tools used to measure the bioavailable fractions of As and Sb. The results of these methods are dependent on many variables, e.g., soil characteristics, contaminant sources, and chemical composition of in vitro methods. Therefore, substantial variations are observed between in vitro and in vivo results obtained from different test animals and endpoints. In this paper, we review the literature on As and Sb bioavailability in terrestrial ecosystems and current in vivo and in vitro techniques used for assessing bioavailability and bioaccessibility of metalloids. This would reveal research gaps and allow scientists and environmental policy makers to gain a deeper understanding of the potential risks associated with these metalloids in the environment.

Does Bt maize expressing CrylAc protein have adverse effects on the parasitoid Macrocentrus cingulum （Hymenoptera： Braconidae）？

The potential effects of insect-resistant, genetically engineered （GE） crops on non-target organisms, especially on predators and parasitoids, must be evaluated before their commercial cultivation. The effects of GE maize that produces CrylAc toxin on the parasitoid Macrocentrus cingulum were assessed by direct bioassay and indirect bioassay. In the indirect bioassay, parasitism rate, cocoon weight and the number of M. cingu- lure progeny produced per host were significantly reduced when M. cingulum-parasitized CrylAc-susceptible Ostriniafurnacalis were fed a diet containing purified CrylAc; how- ever, life-table parameters of M. cingulum were not adversely affected when the same assay was performed with Cry 1Ac-resistant （9. furnacalis. These results indicated that the detrimental effects detected with a CrylAc-susceptible host were mediated by poor host quality. In a direct bioassay, no difference in life-table parameters were detected when M. cingulum adults were directly fed a 20% honey solution with or without CrylAc; however, survival and longevity were significantly reduced when M. cingulum adults were fed a honey solution containing potassium arsenate, which was used as a positive control. The stability and bioactivity of CrylAc toxin in the food sources and CrylAc toxin uptake by the host insect and parasitoid were confirmed by enzyme-linked immunosorbent assay and sensitive-insect bioassays. Our results demonstrate that M. cingulum is not sensitive to CrylAc toxin at concentrations exceeding those encountered in Bacillus thuringiensis maize fields. This study also demonstrates the power of using resistant hosts when assess- ing the risk of genetically modified plants on non-target organisms and will be useful for assessing other non-target impacts.

Contaminants of emerging concern in landfill leachate in China:A review

This review paper summarizes the occurrence,removal and ecological risk of contaminants of emerging concern(CEC)reported in landfill leachate in China since 1996(43 studies in 10 regions).Results show that many more studies are conducted in developed southeastern China than in developing western and northeastern regions in China.Phthalate esters(PAEs,with 15 studies)and pharmaceuticals and personal care products(PPCPs,with 13 studies)are the two most frequently studied CEC classes.Concentrations of nine CECs classes were in a wide range from 0.03(organochlorine pesticides)to approximately 4500 mg/L(alkylphenol polyethoxylates/bisphenol analog).Meanwhile,concentrations of CEC compounds range from below detection limit(e.g.doxycycline)to approximately 4500 mg/L(bisphenol A).Several PAEs(diethyl phthalate,di-n-butyl phthalate,and di(2-ethylhexyl)phthalate)and PPCPs(diclofenac and gemfibrizol)have significant variation between sampling sites.Typically,advanced treatment processes can achieve higher removal efficiencies of CEC compounds from landfill leachate compared with conventional treatment processes.Furthermore,environmental risk assessments of CEC compounds in treated landfill leachate using a risk quotient method show that 2(substituted)polycyclic aromatic hydrocarbons(sPAHs)(benzo(a)anthracene and benzo(b)fluoranthene),2 PPCPs(bezafibrate and sulfapyridine),g-hexachlorocyclohexane,and bisphenol A pose high risk.The importance of monitoring and potential risks of CECs in the leachate to vicinity aquatic environment cross China is addressed.

TRANSPORT OF BICOMPONENT CONTAMINANT IN FREE-SURFACE WETLAND FLOW

This paper presents a theoretical analysis of a pulsed bicomponent contaminant emission into a flee-surface wetland flow. The basic equations are for the bicomponent contaminant transport in the wetland flow under the combined action of advection, mass dispersion, and ecological reaction at the phase averaged scale. The effect of the ecological reaction is separated from the hydrodynamic effect via a set of widely used transforms. The analytical solution for the evolution of the depth-averaged concentration is rigorously derived, with a limiting case covering the known solution for the single component contaminant transport. It is found that the depth-averaged species concentration of the bicomponent contaminant can approach an equilibrium state determined by the distribution coefficient.