States Environmental Protection Research Articles

Reducing the carbon footprint of Hevea rubber carbon composites using surface-modified fly ash

CO2 intensive carbon black (CB) as filler material in natural Hevea rubber-based composites needs to be partially replaced by suitable fillers. In this study, a novel surface modified filler (SuMo FA) was made by encapsulating fly ash (FA) with a polysulphide coating. This SuMo FA was hydrophobic, minimized leaching, and was morphologically ideal as partial replacement filler of CB in Hevea rubber-based composites. This SuMO fly ash and unmodified FA was compounded from 5, 10 and 20 parts per hundred rubber (phr) accounting for partial substitution of CB at 5, 10, 20 and 40 (by weight (wt%)), respectively. The tensile properties and Shore A hardness were practically unchanged with unmodified FA at 5 wt% CB replacement. SuMo FA performed better, retaining tensile properties up to 20 wt% CB replacement. Major decreases were seen only at 40 wt% CB replacement. Chemical crosslink densities decreased somewhat with increasing ash content, while thermal stability remained constant. The encapsulation reduced the leachability of toxic heavy metals from SuMo FA to below United States-Environmental Protection Agency limits opening up the use of such composites in consumer markets in addition to industrial ones. Thus, SuMo FA is a promising waste-derived filler that can be used to partially replace carbon black in rubber composites without loss of mechanical properties or thermal stability.

Exercise of State Control over Local Self-Government in the Field of Environmental Protection

Today, environmental protection is a priority task for the governments of countries around the world due to the deepening of environmental problems and their impact on people's lives. Several problematic issues can and must be solved at the local level, which will make environmental policy more effective and take into account local needs. The study aimed to analyse the competence of local self-government bodies in terms of monitoring compliance with environmental legislation. A comparative analysis was used to study the issue of ensuring the protection of the environment and ecosystem by local self-government bodies through the prism of legal protection. During the research, several obstacles to the implementation of effective environmental protection measures at the local level were identified: the imperfection of the financing system, the lack of environmental awareness, the absence of effective administrative and procedural measures, and the imperfection of state control. In response to the identified problems, the positive experience of implementing the norms of the European Charter of Local Self-Government was investigated. It was established that the decentralization of local self-government had a positive effect on the protection of the ecosystem, as it brought local authorities closer to the public and provided local authorities with real powers to solve problems related to compliance with environmental legislation. In addition, to increase the effectiveness of mechanisms of state control over local self-government in the field of environmental protection, a system of principles of such control is proposed, consisting of publicity, systematicity, effectiveness, objectivity, impartiality, and universality. The proposed system will cover several key environmental problems and quickly and effectively solve them with the involvement of competent specialists and the public. The state of environmental protection at the local level is seen in further research and justification to determine practical recommendations for the implementation of decentralization of local self-government.

Rapid, Selective Extraction of Silver from Complex Water Matrices with a Metal-Organic Framework/Oligomer Composite Constructed via Supercritical CO2.

Every year vast quantities of silver are lost in various waste streams; this, combined with its limited, diminishing supply and rising demand, makes silver recovery of increasing importance. Thus, herein, we report a controllable, green process to produce a host of highly porous metal-organic framework (MOF)/oligomer composites using supercritical carbon dioxide (ScCO2 ) as a medium. One resulting composite, referred to as MIL-127/Poly-o-phenylenediamine (PoPD), has an excellent Ag+ adsorption capacity, removal efficiency (>99 %) and provides rapid Ag+ extraction in as little as 5 min from complex liquid matrices. Notably, the composite can also reduce sliver concentrations below the levels (<0.1 ppm) established by the United States Environmental Protection Agency. Using theoretical simulations, we find that there are spatially ordered polymeric units inside the MOF that promote the complexation of Ag+ over other common competing ions. Moreover, the oligomer is able to reduce silver to its metallic state, also providing antibacterial properties.

Characterization of organic contaminants associated with road dust of Delhi NCR, India.

Hydrophobic organic contaminated polycyclic aromatic hydrocarbons (PAHs), polychlorinated biphenyls (PCBs) and CHNS (carbon, hydrogen, nitrogen and sulphur species) are explosively associated with road dust particles. A few organic contaminants are toxic in nature and have an unpleasant effect on human health. The International Agency for Research on Cancer (IARC), the US Department of Health and Human Services (HHS) and the United States-Environmental Protection Agency has considered several PAHs and PCBs as carcinogens for human beings. In the proposed study, the anthropogenic contaminants present in road dust were assessed in six representative diversified sites i.e. industrial, commercial, office, residential, construction and traffic intersection in Delhi NCR, India. Roadside dust samples were gathered in premonsoon, monsoon and postmonsoon seasons and characterized for PAHs, PCBs and CHNS. The concentration of total PAHs (16 Nos) and PCBs (6 Nos) of the selected sites ranged from 0.27µg/kg to 605.80µg/kg and 0.01µg/kg to 41.26µg/kg, respectively. The Fourier transform infrared spectroscopy-attenuated total reflectance study suggested that the presence of O = C = O, Si-O, carbonyl, acidic or aliphatic esters group were associated with road dust particles. Hydrogen and sulphur concentrations were not detected in the selected road dust samples. Carbon and nitrogen concentrations varied from 2.24% to 16.82% and 0.69% to 14.5%, respectively, seasonally. In the premonsoon season, road dust was distinguishably contaminated as compared to monsoon and postmonsoon season, whichmight be due to movement of contaminated road dust from adjacent locations. It was perceived that Delhi NCR organic contamination inroad dust was much below as compared to other countries. It may be concluded that due to the presence of significant amounts of carbon and nitrogen concentrations in the road dust, to a greater extent, road dust can be fertile and might be advantageous for green belt development to mitigate air pollution. The utilization of road dust will further bring down the burden of landfill sites and may lead towards sustainability.

The impact of altering emission data precision on compression efficiency and accuracy of simulations of the community multiscale air quality model

Abstract. The Community Multiscale Air Quality (CMAQ) model has been a vital tool for air quality research and management at the United States Environmental Protection Agency (US EPA) and at government environmental agencies and academic institutions worldwide. The CMAQ model requires a significant amount of disk space to store and archive input and output files. For example, an annual simulation over the contiguous United States (CONUS) with horizontal grid-cell spacing of 12 km requires 2–3 TB of input data and can produce anywhere from 7–45 TB of output data, depending on modeling configuration and desired post-processing of the output (e.g., for evaluations or graphics). After a simulation is complete, model data are archived for several years, or even decades, to ensure the replicability of conducted research. As a result, careful disk space management is essential to optimize resources and ensure the uninterrupted progress of ongoing research and applications requiring large-scale, air quality modeling. Proper disk-space management may include applying optimal data-compression techniques that are executed on input and output files for all CMAQ simulations. There are several (not limited to) such utilities that compress files using lossless compression, such as GNU Gzip (gzip) and Basic Leucine Zipper Domain (bzip2). A new approach is proposed in this study that reduces the precision of the emission input for air quality modeling to reduce storage requirements (after a lossless compression utility is applied) and accelerate runtime. The new approach is tested using CMAQ simulations and post-processed CMAQ output to examine the impact on the performance of the air quality model. In total, four simulations were conducted, and nine cases were post-processed from direct simulation output to determine disk-space efficiency, runtime efficiency, and model (predictive) accuracy. Three simulations were run with emission input containing only five, four, or three significant digits. To enhance the analysis of disk-space efficiency, the output from the altered precision emission CMAQ simulations were additionally post-processed to contain five, four, or three significant digits. The fourth, and final, simulation was run using the full precision emission files with no alteration. Thus, in total, 13 gridded products (4 simulations and 9 altered precision output cases) were analyzed in this study. Results demonstrate that the altered precision emission files reduced the disk-space footprint by 6 %, 25 %, and 48 % compared to the unaltered emission files when using the bzip2 compression utility for files containing five, four, or three significant digits, respectively. Similarly, the altered output files reduced the required disk space by 19 %, 47 %, and 69 % compared to the unaltered CMAQ output files when using the bzip2 compression utility for files containing five, four, or three significant digits, respectively. For both compressed datasets, bzip2 performed better than gzip, in terms of compression size, by 5 %–27 % for emission data and 15 %–28 % for CMAQ output for files containing five, four, or three significant digits. Additionally, CMAQ runtime was reduced by 2 %–7 % for simulations using emission files with reduced precision data in a non-dedicated environment. Finally, the model-estimated pollutant concentrations from the four simulations were compared to observed data from the US EPA Air Quality System (AQS) and the Ammonia Monitoring Network (AMoN). Model performance statistics were impacted negligibly. In summary, by reducing the precision of CMAQ emission data to five, four, or three significant digits, the simulation runtime in a non-dedicated environment was slightly reduced, disk-space usage was substantially reduced, and model accuracy remained relatively unchanged compared to the base CMAQ simulation, which suggests that the precision of the emission data could be reduced to more efficiently use computing resources while minimizing the impact on CMAQ simulations.

«Птицы и ЛЭП» в России: наследие СССР, современные достижения и вопросы

«Птицы и ЛЭП» в России: наследие СССР, современные достижения и вопросы

Comparison of methods for the enumeration of coliphages in 100 mL water samples

In the last decade coliphages have been included in many water quality regulations as viral faecal indicators. However, the standardised methods used to detect and quantify coliphages differ in bacterial host strains, culture media and techniques. In this comparative study, 100 mL samples of mineral drinking water, river water and wastewater were analysed with International Organization for Standardization (ISO) standard methods, with United States-Environmental Protection Agency (U.S. EPA) based methods as well as commercial kits combining a single agar layer (SAL) assay with ISO bacterial host strains. The three methods gave similar counts (p-value>0.05) for somatic and total coliphages in the matrices with less than 100 PFU/100 mL, whereas for F-specific coliphages, the U.S. EPA method provided statistically significant lower numbers (p-value<0.05) than the other two protocols, possibly because it uses a different bacterial host strain (Escherichia coli HS (pFamp) R vs. the ISO strain Salmonella enterica serovar Typhimurium WG49). In samples with more than 100 PFU/100 mL, the ISO method yielded higher counts of somatic coliphages than the other two protocols (p-value<0.05). As the three methods provided similar results in clean water, the approach combining a SAL assay with the ISO bacterial host strain could be a useful option for coliphage analysis in this type of sample, as it does not require a concentration step.

Evaluation methods for low-cost particulate matter sensors

Abstract. Understanding and improving the quality of data generated from low-cost sensors represent a crucial step in using these sensors to fill gaps in air quality measurement and understanding. This paper shows results from a 10-month-long campaign that included side-by-side measurements and comparison between reference instruments approved by the United States Environmental Protection Agency (EPA) and low-cost particulate matter sensors in Bartlesville, Oklahoma. At this rural site in the Midwestern United States the instruments typically encountered only low (under 20 µg m−3) concentrations of particulate matter; however, higher concentrations (50–400 µg m−3) were observed on 3 different days during what were likely agricultural burning events. This study focused on methods for understanding and improving data quality for low-cost particulate matter sensors. The data offered insights on how averaging time, choice of reference instrument, and the observation of higher pollutant concentrations can all impact performance indicators (R2 and root mean square error) for an evaluation. The influence of these factors should be considered when comparing one sensor to another or when determining whether a sensor can produce data that fit a specific need. Though R2 and root mean square error remain the dominant metrics in sensor evaluations, an alternative approach using a prediction interval may offer more consistency between evaluations and a more direct interpretation of sensor data following an evaluation. Ongoing quality assurance for sensor data is needed to ensure that data continue to meet expectations. Observations of trends in linear regression parameters and sensor bias were used to analyze calibration and other quality assurance techniques.

Determination of Polycyclic Aromatic Hydrocarbons in Soil and Water Around Automobile Repair Workshops within Eket Metropolis in Akwa Ibom State, Nigeria using GC-MS

Polycyclic Aromatic Hydrocarbons (PAHs) are widespread in air, water, terrestrial, and biological systems and can be transferred between these resources. Sixteen United States-Environmental Protection Agency (US-EPA) priority PAHs in soils and underground water from some automobile repair workshops within Eket metropolis in Akwa Ibom State, Nigeria were determined using gas chromatography-mass spectrometry (GC-MS) to assess the extent of pollution caused by automobile repair activities. Soil samples were collected at various depths within five automobile repair workshops using stainless steel hand-held auger. Water samples were also collected from boreholes around the vicinity of the automobile repair workshops using an amber glass bottle with a screw cap. The results obtained showed that all the sixteen US-EPA priority PAHs were detected in varying concentrations in the soil samples while dibenzo(a,h)anthracene was not detected in any of the water samples. The Ʃ16 EPA PAHs detected in the soil samples in the five automobile repair workshops ranged from 0.82-12.98 mg/kg. The Ʃ15 EPA PAHs detected in the water samples ranged from 1.71-16.07 mg/l. According to the European Commission classification system of soil contamination, the soil was classified to be moderate to heavily contaminated. The carcinogenic potency BaP equivalent concentration (BaPeq) for the soil samples ranged from 0.4610-1.5058 mg/kg. The BaPeq for the water samples around the sampling sites ranged from 0.1644-0.4238 mg/l. Diagnostic ratios showed that the possible sources of PAHs in this study area were derived from mixed sources (Pyrogenic, Petrogenic, and phytogenic sources). Hence the soils and water around the workshop are moderately contaminated.

COMMUNITY INTERESTS AND THE PROTECTION OF THE MARINE ENVIRONMENT WITHIN NATIONAL JURISDICTION

AbstractThis article considers the under-studied question of the interests that the international community may have in the protection of the marine environment within national jurisdiction. This question is addressed on the basis of a comprehensive analysis of the major documents that reveal the convictions of the international community, including UN General Assembly resolutions, major international treaties and the outcomes of multilateral conferences. The core argument is that, despite the dominance of the zonal jurisdictional regime in the law of the sea, the international community has, in fact, clearly and consistently demonstrated an interest in the protection of the marine environment within national jurisdiction. Although a finding of community interest does not affect the character of the coastal State's primary environmental protection obligations, it may have implications for the rights of third States to challenge a coastal State's failure to protect its own marine environment. Whether third States choose to exercise this right in practice remains to be seen; however, this article's findings should indicate to States that their actions and policies concerning the protection of the marine environment of their own maritime zones are a matter of concern to all States.

Environmental exposomics and lung cancer risk assessment in the Philadelphia metropolitan area using ZIP code\u2013level hazard indices

To illustrate methods for assessing environmental exposures associated with lung cancer risk, we investigated anthropogenic based air pollutant data in a major metropolitan area using United States-Environmental Protection Agency (US-EPA) Toxic Release Inventory (TRI) (1987–2017), and PM2.5 (1998–2016) and NO2 (1996–2012) concentrations from NASA satellite data. We studied chemicals reported according to the following five exposome features: (1) International Agency for Research on Cancer (IARC) cancer grouping; (2) priority EPA polycyclic aromatic hydrocarbons (PAHs); (3) component of diesel exhaust; (4) status as a volatile organic compound (VOC); and (5) evidence of lung carcinogenesis. Published articles from PubChem were tallied for occurrences of 10 key characteristics of cancer-causing agents on those chemicals. Zone Improvement Plan (ZIP) codes with higher exposures were identified in two ways: (1) combined mean exposure from all features, and (2) hazard index derived through a multi-step multi-criteria decision analysis (MMCDA) process. VOCs, IARC Group 1 carcinogens consisted 82.3% and 11.5% of the reported TRI emissions, respectively. ZIP codes along major highways tended to have greater exposure. The MMCDA approach yielded hazard indices based on imputed toxicity, occurrence, and persistence for risk assessment. Despite many studies describing environmental exposures and lung cancer risk, this study develops a method to integrate these exposures into population-based exposure estimates that could be incorporated into future lung cancer screening trials and benefit public health surveillance of lung cancer incidence. Our methodology may be applied to probe other hazardous exposures for other cancers.

Determination of heavy metals and health risk assessment in indoor dust from different functional areas in Neyshabur, Iran

The concentration of 10 potentially toxic heavy metals in indoor dust from homes in Neyshabur was investigated. The concentrations of heavy metals in indoor dust from homes ranged from 28.1 to 190.4 µg g−1 for Cr, 24.7 to 162.2 µg g−1 for Ni, 43.8 to 640.4 µg g−1 for Cu, 13.7 to 5,345.7 µg g−1 for Pb, 135.5 to 1,033.0 µg g−1 for Mn, 105.8 to 2,958.0 µg g−1 for Zn, 6,288.0 to 32759.8 µg g−1 for Fe, 2,916.5 to 37,990.0 µg g−1 for Al, 1.3 to 21.4 µg g−1 for Co and 0.5 to 12.9 µg g−1 for Cd. Results of the concentrations of heavy metals in this study were compared with values reported in other parts of the world. Statistical tests revealed no significant relationship between tobacco use and measured heavy metal concentrations. The range of United States-Environmental Protection Agency safe limits (1 × 10−4 and 1 × 10−6) indicates that cancer risk of Cr in age groups of both children and adults (1.6 × 10−3 and 5.5 × 10−3) is higher. For all studied elements, the obtained hazard index was found to be &lt;1, which means they are at safe levels of metals. The principal component analysis showed that Co, Mn and Fe form an independent cluster with no relationship with other metals. The overall enrichment factor was close to 10, which suggests having a natural source.

New evidence on the soft budget constraint: Chinese environmental policy effectiveness in SOE-dominated cities

This paper analyzes the efficiency of a set of environmental measures introduced by China’s 11th Five-Year Plan in 2006, using a rich and unique data set assembled from the Ministry of Environmental Protection and the State Environmental Protection Agency. By exploiting plausibly exogenous variation in regulatory stringency generated by the regulatory system across China’s provinces, we find evidence that pollution-intensive cities reduced their SO2 emissions substantially, whereas cities with a strong state-owned enterprise (SOE) presence did not. We interpret the results as pointing to evidence of Chinese SOEs’ ongoing soft budget constraints. The findings are robust to the inclusion of different fixed effects and other key determinants of pollution. Moreover, we investigate the main factors underlying regulatory non-compliance: the overlapping (or not) of “Two Control Zone” (Special Policy Zone, Coastal) cities wherein environmental (growth) policies are prioritized; the existence of turning points below (above) which growth and reductions in pollution substitute for (complement) each other; the size and extent of industrial concentration, which determines the possibilities of firms negotiating with the local authorities; and finally, the regulation-induced adoption of cleaner technologies by polluting firms, which enhance productivity and lower SO2 emissions.

Accumulation Characteristics, Tolerance Differences and Risk Assessment of Heavy Metals in Sugarcane

Seven varieties of sugarcane were grown on soil polluted with heavy metals, including Pb, Cd, and As. Sugarcane growth, the heavy metal contents in different sugarcane tissues, and the subcellular distributions of the heavy metals in the roots and leaves were analyzed. The purpose of this investigation was to study sugarcane growth tolerance, the accumulation of heavy metals and the mechanism of sugarcane tolerance to heavy metals at the subcellular level. Health risk assessments were performed according to the models recommended by the United States Environmental Protection Agency (US EPA). The patterns of heavy metal storage were demonstrated to differ among different tissues in all sugarcane varieties investigated. Most of the heavy metals that were absorbed accumulated in the roots of the sugarcane, and the heavy metals in the root cells were mostly located in the cell wall. The health risk index was used to analyze the juice and indicated that the consumption of sugarcane juice by adults and children posed no significant health risks. This study shows that sugarcane grown on heavy metal-contaminated farmland is safe for consumption. The results of this study revealed an important and positive implication regarding the cultivation of sugarcane on farmland that is polluted by heavy metals and the potential to simultaneously achieve sustainable economic output and potential environmental restoration.

Governance networks in marine spaces where fisheries and oil coexist: Tabasco, México

Coupled Socio-Ecological Systems (SES) are frequent in the sea where several human activities coexist in a common space, maintaining individual attributes, but also creating inherent characteristics of this spatiotemporal coupling. The governance system, which minimises conflicts through maximizing agreements, offers an opportunity to achieve a balance between sectoral agendas. Establishing effective governance is challenging in the Southern Gulf of Mexico, where the new Energetic Reform (2013) has stressed the historically fragile equilibrium between fisheries and the oil industry. Through a Social Network Analysis (SNA), this work aims to identify the governance network directly involved in the decision-making process over the fishing-oil Socio-Ecological System (FOSES) of the coast of Tabasco. The mapping of 53 key actors (classified in eight functional groups) shows that the cohesion between them is low compared to the number of maximum relationships that could be established in the network. The distribution of the actors can be appreciated in three governance agendas. The energy agenda is ruled by the state oil company (PEMEX) and the Mexican Navy, while the social-fishing and intermediary environmental agendas are dominated by the fishing sector and the state environmental protection agency, respectively.

Legal Prevention and Dispute Settlement of Cross-Border Investment Risks of Chinese Private Enterprises under the "One Belt and One Road" Initiative

&lt;p&gt;With the initiative of "One Belt and One Road “and the continuous development of China area, the current domestic private enterprises in transnational investment faces some risks, and these risks are mainly concentrated in the process of overseas investment in several stages for market access, asset operations and assets withdrawal. It mainly covers the scope of the foreign capital enterprise property rights, investment, the state environmental protection, tax policy, intellectual property protection, local labor protection and capital withdrawal, etc. This paper attempts to objectively analyze the legal risks of cross-border investment of Chinese private enterprises in the “One Belt and One Road” environment, so as to establish a “One Belt and One Road” overseas transnational investment risk prevention system and conflict resolution mechanism with legal prevention as the main content.&lt;/p&gt;

Striving for consistency in the National Wetland Condition Assessment: developing a reference condition approach for assessing wetlands at a continental scale

One of the biggest challenges when conducting a continental-scale assessment of wetlands is setting appropriate expectations for the assessed sites. The challenge occurs for two reasons: (1) tremendous natural environmental heterogeneity exists within a continental landscape and (2) reference sites vary in quality both across and within major regions of the continent. We describe the process used to set reference expectations and define a disturbance gradient for the United States (US) Environmental Protection Agency’s National Wetland Condition Assessment (NWCA). The NWCA employed a probability design and sampled 1138 wetland sites across the conterminous US to make an unbiased assessment of wetland condition. NWCA vegetation data were used to define 10 reporting groups based on ecoregion and wetland type that reduced the naturally occurring variation in wetland vegetation associated with continent-wide differences in biogeography. These reporting groups were used as a basis for defining quantitative criteria for least disturbed and most disturbed conditions and developing indices and thresholds for categories of ecological condition and disturbance. The NWCA vegetation assessment was based on a reference site approach, in which the least disturbed reference sites were used to establish benchmarks for assessing the condition of vegetation at other sites. Reference sites for each reporting group were identified by filtering NWCA sample data for disturbance using a series of abiotic variables. Ultimately, 277 least disturbed sites were used to set reference expectations for the NWCA. The NWCA provided a unique opportunity to improve our conceptual and technical understanding of how to best apply a reference condition approach to assessing wetlands across the US. These results will enhance the technical quality of future national assessments.

The reduction of carbon dioxide emission at 3R Superdepo Sutorejo waste processing unit (TPS), Surabaya

This research aims to know waste volume, waste composition, and emission reduction through sorting and without sorting at Superdepo Sutorejo Waste Processing Unit (TPS), Surabaya. The calculation of waste volume and composition was carried out in accordance with SNI 19-3964-1994, while the calculation of carbon dioxide emission was based on the United States-Environmental Protection Agency (US-EPA). The results showed that the solid waste volume in Superdepo Sutorejo Waste Processing Unit was 0.7 kg/person/day with organic waste composition percentage of 63%, plastic waste of 15.22%, paper of 5.36%, aluminium of 2.22%, glass of 1.31%, rubber 0.78%, and residual waste of 12.09%. Carbon dioxide emission without waste sorting was amounted to 9,087.05 MTCO2E/year while carbon dioxide emissions through waste sorting was amounted to 8,512.5 MTCO2E/year. Therefore, the sorting at 3R Superdepo Sutorejo Waste Processing Unit (TPS) Surabaya could store the emission of carbon dioxide by 6.3%.

Etude de la contamination en hydrocarbures aromatiques polycycliques dans les sédiments et les eaux au nord Liban: rivières, zones de transition et sites portuaires

Contamination of the marine environment is associated with continental activities, marine activities and accidental spills. Providing answers to the origin of the contamination ofthe aquatic environment by PAHsis an objective of the present work. The originality of this work is to study pollutants in two types of matrix (water and sediments) during2 seasons (dry and wet) for an environmental monitoringof 6 years. This study provides a more complete overview of the state of contaminationin three coastal rivers, their transition zones and harborsin the Eastern Mediterranean following the Jiyyeh oil spill in 2006.Contaminantsconcentrations wereexpressed asthe sum of the 16 PAHs classified as prority substances by the United StatesEnvironmental Protection Agency(US-EPA). Overall,contamination was noted for all the analyzedsites. Oil spill seem to be one of the main sources of pollution in the area, as the highest levels of PAH(&gt; 9000 ng.g-1s.w&amp;&gt; 8000 ng.L-1) were reported in the coastal environment of the three rivers and harbors.High levels of PAHswere also observed in rivers transitional zones, revealing the importance of terrestrial inputs (untreated wastewater discharge, leachate, solid wastes, etc.).Comparing the PAHsconcentrations measured in the sediments of the sitesanalyzed with the empirical sediment quality criteria "SQG" for the support of the general assessment of sediment toxicity, we can notice that some individual PAHand their sum can present a significant ecotoxicological risk to aquatic organisms. Further research through monitoring campaigns and toxicity tests is encouraged, as the exposure of the resident aquatic organisms and human population to these chemicals might be expected to increase over the years.

Receiving Water Quality Models for TMDL Development and Implementation

Water quality models are critical tools for the development of total maximum daily loads (TMDLs) and for the evaluation of water quality management alternatives by stakeholders and state environmental protection agencies. Currently there is a large availability of water quality models that can be used to support TMDL studies, and the selection of a particular model requires a good understanding of the model limitations, capabilities, and data requirements. The ASCE/Environmental and Water Resources Institute (EWRI) TMDL Analysis and Modeling Task Committee was established in part to produce guidance documentation to help modelers to identify and implement existing modeling approaches to address some of the most important causes of water quality impairment in the United States, including eutrophication, toxic chemicals, and metals. This paper presents a review of existing mathematical models to evaluate eutrophication processes, including carbon and nutrient cycling, phytoplankton dynamics, and dissolved oxygen availability, as well as a review of mathematical models to simulate the fate and transport of toxic chemicals and mercury. The paper also discusses the main capabilities and limitations of 11 widely used water quality models in the United States. Modelers can use this information to support more informed model selections and to facilitate an effective and successful application of models in TMDL studies.