Pollutant Export Research Articles

Specific Features of the Formation of Water Flow and Pollution Export from Agricultural, Forest, and Urbanized Landscapes

The overland flow from different landscapes during flood season and its variations under the effect of agrotechnical activities and climate in the southern Russian Plain have been evaluated based on the analysis of data from water balance plots. The present-day overland flow in forest steppe and steppe regions has been shown to be several times less than that 50–70 years ago. At the same time, the infiltration runoff (perched-water and groundwater runoff) has increased. The structure of the present-day river runoff and the contribution of the overland flow, the runoff from a hydrographic network area, and the runoff of infiltration origin in individual natural zones to the formation of the river runoff have been determined. The export of biogens in the Volga and Don basins, including that in urbanized areas, has been calculated based on the analysis of water samples in different landscape zones. Such export from urbanized landscapes has been shown to contribute little to the total export of biogens in these basins. The volume of biogens of diffuse origin considerably exceeds that of biogens carried out by wastewater. However, this relationship may change for large rivers and reservoirs since river water carrying diffuse biogens mostly moves for a long time before it reaches the main river partially self-purified, whereas wastewater biogens mainly directly flow into large rivers.

The Effects of Urbanization and Retention‐Based Stormwater Management on Coastal Plain Stream Nutrient Export

AbstractStormwater nutrient pollution can be more effectively managed if there is a predictable link between urbanization and pollutant export. The goal of this study was to determine the effects of increased watershed impervious surface cover (ISC) and retention‐based stormwater management on stream discharge and nutrient export from coastal plain streams in the southeastern United States. To quantify coastal plain stream nutrient export, measurements of stream discharge and concentrations of dissolved nutrients, particulate nitrogen, and algal biomass (as chlorophyll a) were collected during baseflow and stormflow for four years from five streams on Marine Corps Base Camp Lejeune near Jacksonville, North Carolina. The study streams had watersheds that spanned a range of ISC (1–38%) and included an urban watershed drained extensively by stormwater ponds. Urban streams had higher rates of annual discharge than less impacted streams due to elevated discharge at all rates of flow, more cumulative discharge at high flows, and dampened seasonal patterns. Streams with higher watershed ISC had higher rates of annual export of all measured nutrients due to increased stream discharge and concentrations of inorganic and particulate nitrogen. The relative importance of dissolved organic nitrogen decreased with watershed ISC, but it was still the dominant form of nitrogen export in every study stream except the stream that was dominated by particulate nitrogen export from stormwater pond algal production. Based on these findings, this study suggests that stormwater management emphasizing stormwater harvesting and evapotranspiration, increased wetland area, and decreased anthropogenic nutrient sources could reduce nutrient export from urban coastal plain streams.

An approach to develop grey water footprint accounting

Abstract Grey water footprint (GWF) is an indicator that represents the water quality issues embedded in producing a product in form of freshwater volume. This indicator converts the pollution loads to the equivalent volume of freshwater with respect to the assimilative capacity of the receiving water body. This study develops the method of accounting multiple-pollutant GWF with ecological perspective. For demonstrating the developed methodology, original samples were taken from trout farms in the Kabkian River, south-western Iran, and the pollution exports are calculated in first step. In the second step, river is modelled for determining the local-oriented water quality standards. Finally, total multiple-pollutant GWF is determined. Here, equations are developed for considering dissolved oxygen (DO) in accounting GWF due to the critical role of this parameter in aquaculture and fish production. In addition, a state-of-the-art coefficient is introduced to alter the formulation for including the environmental issues of receiving water body in accounting GWF. This can provide a framework for considering Eutrophication, saline intrusions, minimum environmental flow and DO deficit of river, in addition to the risks of micropollutants in water footprint assessments. Nevertheless, the results of case study show that GWF is nitrogen-related for trout farming. It equals 195 m3/ton but it may fluctuate depending on the local development strategies and their consequences on the environmental issues. Consequently, the proposed methodology can broaden the prospect of the application of GWF and enhance the role of environmental capacity in this indicator.

Optimization of pollutant reduction system for controlling agricultural non-point-source pollution based on grey relational analysis combined with analytic hierarchy process

Many technologies have been developed to control agricultural non-point-source pollution (ANPSP). However, most reduce pollution from only a single source instead of considering an entire region with multiple pollution sources as a control unit. A pollutant reduction system for controlling ANPSP at a regional scale could be built by integrating technologies and the reuse of treated wastewater (TWR) and nutrients (NR) to protect the environment and achieve agricultural sustainability. The present study proposes four systematic schemes involving TWR for irrigation and NR in a region with three sources of ANPSP (crop farming, livestock and aquaculture). Subsequently, a multi-objective evaluation model is established based on the analytical hierarchy process (AHP) combined with grey relational analysis (GRA) to identify the optimal scheme considering six indices, namely, pollutant reductions (total nitrogen, TN; total phosphorous, TP; ammonium-nitrogen, NH4+-N; and chemical oxygen demand, COD) and costs (construction and operational costs). The Taihu Lake Basin suffers from some of the worst ANPSP in China, and a case study was conducted in a town with three ANPSP sources. Four systems were developed on the basis of suggested technologies and the scenarios of TWR and NR (Scenario I: no reuse, Scenario II: reuse of all livestock wastewater and manure, Scenario III: reuse of some aquaculture wastewater, and Scenario IV: reuse of all livestock wastewater and manure and some aquaculture wastewater). Pollutant reductions were calculated based on removal efficiency and pollutant loads, which were estimated from the local pollutant export coefficients and agricultural information (crop farming, livestock, and aquaculture). The costs were determined on the basis of the total pollutant reductions and unit cost. The results showed that the optimal system was the Scenario IV because it had the highest grey correlation degree among the four proposed systems. The optimal system met the irrigation water demand in Xinjian. In the optimal system, the removal efficiencies of the pollutants TN, TP, NH4+-N, and COD were 84.3%, 94.2%, 89.6% and 94.0%, respectively. In addition, the implementation of NR in the optimal system reduced the use of chemical fertilizers by nearly 81.7 kg N ha−1 and 39.9 kg P ha−1. The proposed methods provide a reference for the construction of a pollutant reduction system for controlling ANPSP in a multi-source region.

Trend analysis of rainfall characteristics and its impact on stormwater runoff quality from urban and agricultural catchment

Climate change has significantly affected the rainfall characteristics which can influence the pollutant build-up and wash-off patterns from the catchment. Therefore, this study explored the influence of varying rainfall characteristics on urban and agricultural runoff pollutant export using statistical approaches. For this purpose, Mann-Kendall and Pettitt\'s test were applied to detect the trend and breakpoint in rainfall characteristics time series. In addition, double mass curve and correlation analysis were used to drive the relationship between rainfall-runoff and pollutant exports from both catchments. The results indicate a significant decreased in total rainfall and average rainfall intensity, while a significant increased trend for antecedents dry days and total storm duration over the study periods. The breakpoint was determined to be 2013 which shows remarkable trend shifts for total rainfall, average rainfall intensity and antecedents dry days except total duration. Double mass curve exhibited a straight line with significant rainfall-runoff relationship indicates a climate change effect on both sites. Overall, higher pollutant exports were observed at both sites during the baseline period as compared to change periods. In agricultural site, most of the pollutants exhibited significant (p< 0.05) association with total rainfall, average rainfall intensity and total storm duration. In contrast, pollutants from urban site significantly correlated with antecedent dry days and average rainfall intensity. Thus, total rainfall, average rainfall intensity and total duration were the significant factors for the agricultural catchment while, antecedents dry days and average rainfall intensity were key factors in build-up and wash-off from the urban catchment.

Four-year Measurements of Wet Mercury Deposition at a Tropical Mountain Site in Central Taiwan

ABSTRACT Rainwater samples were collected between 2010 and 2013 at Lulin Atmospheric Background Station (LABS) to study the distribution and characteristics of wet mercury (Hg) deposition, and possible driving mechanisms. Sample Hg concentrations ranged from 0.8 to 35.1 ng L–1 with an overall volume-weighted mean (VWM) concentration of 9.2 ng L–1. Annual wet Hg deposition fluxes ranged between 24.4 and 48.9 µg m–2 with a mean value of 32.3 µg m–2. This mean annual wet flux was about 1.5–6.0 times the values measured at 15 sites in the U.S. and 4–16 times the values reported from mountain and high-elevation sites in China. Both rainwater Hg concentration and rainfall amount contributed to this geographical difference, but rainfall amount played a more important role. This indicated that tropical mountains in East and Southeast Asia, especially the windward maritime slopes with abundant rainfall, could be hot spots of wet Hg deposition. Wet Hg deposition flux was high in summer because of elevated rainwater Hg concentrations and high rainfall. The seasonal pattern of rainwater Hg concentrations was different from that of the East Asian air pollutant export, indicating other factors, e.g., rainfall type, were also influencing rainwater Hg concentrations. A clear difference in seasonal frequency distribution of rainfall types was observed, with rain events associated with the Pacific high pressure type (PH) occurring more frequently in summer months. PH rainfall type had the highest VWM Hg concentration (13.5 ng L–1), 2.3–6.2 ng L–1 greater than those of the other rainfall types. Because of intense surface heating under summer PH conditions, precipitation systems usually form locally due to strong convection, resulting in afternoon shower. Therefore, the elevated rainwater Hg levels in summer at LABS were likely due to the scavenging of free tropospheric gaseous oxidized Hg (GOM) by deep convection.

A Study on Marine Pollution Management and Export of Ballast Water

A Study on Marine Pollution Management and Export of Ballast Water

Identification of regional water resource stress based on water quantity and quality: A case study in a rapid urbanization region of China

The stress assessment of water resources is very important for water resource management. How to identify the patterns of water resource stress is urgently important in rapid urbanization regions. Existing studies typically focused on one aspect of water resources and have lacked the completion of a comprehensive analysis. This study proposed a quantitative method of hotspot analysis based on water quantity and quality. Using the Beijing-Tianjin-Hebei region (so-called Jing-Jin-Ji) of China as a case study, the water resource stress was assessed based on the calculations of the water footprint per capita and non-point source pollution export intensities at the county scale. The results showed that (1) The water footprint per capita had great spatial variability in this region, ranging from 524.37 m3 to 897.32 m3 of the counties, and the water footprint per capita was decreased in the order of Beijing (861.71 m3)＞Tianjin (748.92 m3)＞Hebei (566.74 m3). (2) The non-point source total nitrogen and total phosphors export intensities in this region were much higher than those in other regions of China. (3) The stress patterns of water resources in the Beijing-Tianjin-Hebei region's counties could be divided into four categories. More than 60% of the counties had a low water footprint per capita-high non-point source pollution pattern. The low water footprint per capita-low non-point source pollution counties were mainly in Zhangjiakou and Chengde, as well as some mountainous counties in the west of Baoding and Xingtai. The core counties of Beijing, Tianjin, Shijiazhuang, Baoding, Handan, and Qinhuangdao, and the northern mountainous counties of Beijing were high water footprint per capita-low non-point source pollution counties. The high water footprint per capita-high non-point source pollution counties were primarily the non-core counties of Beijing and Tianjin. This study indicated that the priority counties in terms of water resource management could be identified by combining the water footprint with non-point source pollution exports. This method can be easily extended to other regions at home and abroad.

An improved export coefficient model to estimate non-point source phosphorus pollution risks under complex precipitation and terrain conditions.

To control non-point source (NPS) pollution, it is important to estimate NPS pollution exports and identify sources of pollution. Precipitation and terrain have large impacts on the export and transport of NPS pollutants. We established an improved export coefficient model (IECM) to estimate the amount of agricultural and rural NPS total phosphorus (TP) exported from the Luanhe River Basin (LRB) in northern China. The TP concentrations of rivers from 35 selected catchments in the LRB were used to test the model's explanation capacity and accuracy. The simulation results showed that, in 2013, the average TP export was 57.20t at the catchment scale. The mean TP export intensity in the LRB was 289.40kg/km2, which was much higher than those of other basins in China. In the LRB topographic regions, the TP export intensity was the highest in the south Yanshan Mountains and was followed by the plain area, the north Yanshan Mountains, and the Bashang Plateau. Among the three pollution categories, the contribution ratios to TP export were, from high to low, the rural population (59.44%), livestock husbandry (22.24%), and land-use types (18.32%). Among all ten pollution sources, the contribution ratios from the rural population (59.44%), pigs (14.40%), and arable land (10.52%) ranked as the top three sources. This study provides information that decision makers and planners can use to develop sustainable measures for the prevention and control of NPS pollution in semi-arid regions.

PAHs in the Northern South China Sea: Horizontal transport and downward export on the continental shelf

Abstract To investigate horizontal transport and particulate export of semivolatile pollutants on the continental shelf or marginal sea, surface and depth water samples were collected across the northern South China Sea (SCS) and analyzed for polycyclic aromatic hydrocarbons (PAHs). The total concentrations of Σ 15 PAH in seawater were in the range of 1.6–14 ng L −1 (mean 5.5 ng L −1 ), and the offshore decreasing trend of PAHs revealed intense terrigenous transport on the continental shelf, which was originated from combustion activity. Vertically, PAHs in the particulate phase followed surface-enrichment and depth-depletion pattern with a concentration maximum (2.9 ng L −1 ) at the biomass maximum, while the dissolved PAH concentrations showed a minimum (1.5 ng L −1 ) at the same depth. Particulate export fluxes of PAHs were between 24 and 195 ng m −2 d −1 in the northern SCS based on 238 U/ 234 Th equilibria, which is suggested appropriate to quantify their downward flux in the upper water column. Efficient oceanic biological pump drives PAHs downward export to the deep ocean in the northern SCS.

Stream Mercury Export in Response to Contemporary Timber Harvesting Methods (Pacific Coastal Mountains, Oregon, USA).

Land-use activities can alter hydrological and biogeochemical processes that can affect the fate, transformation, and transport of mercury (Hg). Previous studies in boreal forests have shown that forestry operations can have profound but variable effects on Hg export and methylmercury (MeHg) formation. The Pacific Northwest is an important timber producing region that receives large atmospheric Hg loads, but the impact of forest harvesting on Hg mobilization has not been directly studied and was the focus of our investigation. Stream discharge was measured continuously, and Hg and MeHg concentrations were measured monthly for 1.5 years following logging in three paired harvested and unharvested (control) catchments. There was no significant difference in particulate-bound Hg concentrations or loads in the harvested and unharvested catchments which may have resulted from forestry practices aimed at minimizing erosion. However, the harvested catchments had significantly higher discharge (32%), filtered Hg concentrations (28%), filtered Hg loads (80%), and dissolved organic carbon (DOC) loads (40%) compared to forested catchments. MeHg concentrations were low (mostly <0.05 ng L-1) in harvested, unharvested, and downstream samples due to well-drained/unsaturated soil conditions and steep slopes with high energy eroding stream channels that were not conducive to the development of anoxic conditions that support methylation. These results have important implications for the role forestry operations have in affecting catchment retention and export of Hg pollution.

Regulatory Challenges in the Phasing-Out of Persistent Organic Pollutants in Indonesia

The adverse effect of Persistent Organic Pollutants (POPs) which includes endocrin disruptions, cancer, heart disease, impairment of the reproductive system, diabetes and obesity, among others, are very well documented. The Stockholm Convention on Persistent Organic Pollutants (182 state parties) restricts and prohibits the production, use, emission, import and export of persistent organic pollutants. Nevertheless, implementation of the Stockholm Convention by a country may require some adjustment in its national legal system. Indonesia ratified the Stockholm Convention in 2009; however, its implementation has not been smooth. This article analyses Indonesia’s environmental and other relevant legislation and outlines the challenges that need immediate resolution so that the Stockholm Convention can be fully implemented. This article contends that there are gaps within the Indonesian legal framework which need to be addressed, namely: (i) redefinition and recategorisation of regulated objects beyond ‘substances’ so that it covers ‘articles’ and ‘mixtures’ (ii) ways to cope with a growing list of POPs and (iii) gaps in the regulation of POPs life cycle, from production to import, use, registration, storage, disposal and ‘unintentional release’ as well as (iv) the need for new environmental and product standards.

Impact of rainfall patterns and frequency on the export of pesticides and heavy-metals from agricultural soils

The combined influence of soil characteristics, pollutant aging and rainfall patterns on the export of pollutants from topsoils is poorly understood. We used laboratory experiments and parsimonious modeling to evaluate the impact of rainfall characteristics on the ponding and the leaching of a pollutant mixture from topsoils. The mixture included the fungicide metalaxyl, the herbicide S-metolachlor, as well as copper (Cu) and zinc (Zn). Four rainfall patterns, which differed in their durations and intensities, were applied twice successively with a 7days interval on each soil type. To evaluate the influence of soil type and aging, experiments included crop and vineyard soils and two stages of pollutant aging (0 and 10days). The global export of pollutants was significantly controlled by the rainfall duration and frequency (P<0.01). During the first rainfall event, the longest and most intense rainfall pattern yielded the largest export of metalaxyl (44.5±21.5% of the initial mass spiked in the soils), S-metolachlor (8.1±3.1%) and Cu (3.1±0.3%). Soil compaction caused by the first rainfall reduced in the second rainfall the leaching of remaining metalaxyl, S-metolachlor, Cu and Zn by 2.4-, 2.9-, 30- and 50-fold, respectively. In contrast, soil characteristics and aging had less influence on pollutant mass export. The soil type significantly influenced the leaching of Zn, while short-term aging impacted Cu leaching. Our results suggest that rainfall characteristics predominantly control export patterns of metalaxyl and S-metolachlor, in particular when the aging period is short. We anticipate our study to be a starting point for more systematic evaluation of the dissolved pollutant ponding/leaching partitioning and the export of pollutant mixtures from different soil types in relation to rainfall patterns.

Potential impacts of urban land expansion on Asian airborne pollutant outflows

AbstractEastern part of China (EPC) has experienced rapid urbanization during the past few decades. Here we investigate the impacts of urban land expansion over EPC on the export of Asian pollutants to the western Pacific during January, April, July, and October of 2009 using the Weather Research and Forecasting model coupled to Chemistry (WRF/Chem) and a single‐layer urban canopy scheme. Over urbanizing areas, increases in the urban land fraction result in a linearly enhanced uplift of surface primary pollutants to higher altitudes. We further examine how this local effect would change outflows of Asian pollutants to the western Pacific using the tagged black carbon (BC) and carbon monoxide (CO) tracers emitted from EPC (denoted by BCt and COt, respectively). Overall, a 0.1 increase in the fraction of land area that is urban over EPC would linearly (R2 = 0.70–0.96) increase the mean tropospheric eastward export of BCt and COt across meridional planes (i.e., 135°E and 150°E) by 4–40% and 1–6% in different months, respectively. The relative perturbation in exporting efficiency generally maximizes during July while minimizes during April. The urbanization‐export relationship is largely driven by the elevation effect and is also impacted by urbanization‐forced changes in zonal winds. The spatial pattern of the response of BCt over the downwind Pacific differs from that of COt mainly due to aerosol‐cloud interactions. Our findings demonstrate that extensive urban land expansion could substantially impact climate and air quality from a local scale to a regional scale, especially for shorter‐lived air pollutants such as BC and other aerosols.

Development of regional pollution export coefficients based on artificial rainfall experiments and its application in North China

The Export Coefficient Model (ECM) has been widely used to estimate nonpoint source (NPS) pollution loads due to its ease of application. Accurate pollution export coefficients are crucial for reducing uncertainties in load estimation. By integrating artificial simulated rainfall experiments with field survey data, we have developed a new method that estimates regional pollution export coefficients. Results showed that the export coefficients calculated using this new method accurately express the regional rainfall–runoff characteristics, as the simulation precision of this method had grown by 30% than the results with traditional ECM and export coefficients which surveyed from the literature. Based on the calculated regional pollutant export coefficient, the annual loads of TN and TP in the plains area of the Baiyangdian basin in 2010 were 25,967.13 t and 4349.29 t, respectively. Among different types of sources, rural livestock had the greatest contribution (over 60%), whereas rural domestic waste represented the smallest contribution (approximately 10%). Of the different sources, pigs contributed almost half of all NPS pollution from livestock, rural residential areas were the main land use pollution source, and rural living garbage was the main source of rural domestic waste. Spatially, NPS was mainly distributed in the Zhulong and Juma watersheds. Other watersheds only contributed approximately 5% NPS per watershed. However, the per-area loads of these lower load watersheds were larger or nearly equal to that of the Zhulong watershed. Therefore, the lower load watersheds should be addressed for the control of NPS pollution.

Continental pollution in the Western Mediterranean basin: large variability of the aerosol single scattering albedo and influence on the direct shortwave radiative effect

Abstract. Pollution aerosols strongly influence the composition of the Western Mediterranean basin, but at present little is known on their optical properties. We report in this study in situ observations of the single scattering albedo (ω) of pollution aerosol plumes measured over the Western Mediterranean basin during the TRAQA (TRansport and Air QuAlity) airborne campaign in summer 2012. Cases of pollution export from different source regions around the basin and at different altitudes between ∼ 160 and 3500 m above sea level were sampled during the flights. Data from this study show a large variability of ω, with values between 0.84–0.98 at 370 nm and 0.70–0.99 at 950 nm. The single scattering albedo generally decreases with the wavelength, with some exception associated to the mixing of pollution with sea spray or dust particles over the sea surface. The lowest values of ω (0.84–0.70 between 370 and 950 nm) are measured in correspondence of a fresh plume possibly linked to ship emissions over the basin. The range of variability of ω observed in this study seems to be independent of the source region around the basin, as well as of the altitude and aging time of the plumes. The observed variability of ω reflects in a large variability for the complex refractive index of pollution aerosols, which is estimated to span in the large range 1.41–1.77 and 0.002–0.097 for the real and the imaginary parts, respectively, between 370 and 950 nm. Radiative calculations in clear-sky conditions were performed with the GAME radiative transfer model to test the sensitivity of the aerosol shortwave Direct Radiative Effect (DRE) to the variability of ω as observed in this study. Results from the calculations suggest up to a 50 and 30 % change of the forcing efficiency (FE), i.e. the DRE per unit of optical depth, at the surface (−160/−235 W m−2 τ−1 at 60° solar zenith angle) and at the Top-Of-Atmosphere (−137/−92 W m−2 τ−1) for ω varying between its maximum and minimum value. This induces a change of up to an order of magnitude (+23/+143 W m−2 τ−1) for the radiative effect within the atmosphere.

Summer atmospheric composition over the Mediterranean basin: Investigation on transport processes and pollutant export to the free troposphere by observations at the WMO/GAW Mt. Cimone global station (Italy, 2165 m a.s.l.)

In this work, we analysed reactive gases (O3, CO, NOx) and aerosol properties (eqBC, σs and particle number concentration) collected at the WMO/GAW Mt. Cimone station (2165 m a.s.l., Italy) during the summer of 2012 in the framework of PEGASOS project. The major aim of this experiment is providing a characterization of the variability of summer atmospheric composition over the central Mediterranean basin, which is considered as a global “hot-spot” for atmospheric pollution and climate change.The atmospheric tracers have been analysed as a function of (i) meteorological parameters, (ii) synoptic-scale circulation and (iii) anthropogenic emission source proximity as estimated by O3/NOx ratio variability. In particular, we identified three O3/NOx regimes which tagged the distance of anthropogenic sources: near outflow (23% of hourly data), far-outflow (38% of data) and background (39% of data). The highest levels of anthropogenic pollutants (e.g. O3, CO, eqBC, accumulation particles) were concomitant with fresh emissions from northern Italy under near-outflow conditions: once injected to the free troposphere, these air-masses, rich in pollutants and climate-forcers (i.e. O3, eqBC) and soil dust, can be spread over a large region, thus significantly affecting regional climate. Moreover, based on the anthropogenic source proximity, atmospheric tracer variability and synoptic-scale atmospheric circulation, we categorized and characterised four types of atmospheric regimes associated with (1) air-mass transport from the free troposphere, (2) transport of fresh emitted pollutants from the PBL, (3) transport at regional/continental scale of aged anthropogenic (4) transport of air-mass rich in mineral dust from northern Africa (i.e. coming from more than 1000 km).Lastly, by analysing the probability density functions (PDFs) of trace gases and aerosol properties, “fingerprints” of the mentioned atmospheric regimes were pointed out. Such information is useful for the implementation of early-warning services, for the timely detection of event occurrence as well as for the definition of observation-based diagnostic for model verifications.

Predicting precipitation on nonpoint source pollutant exports in the source area of the Liao River, China.

The source area of the Liao River is an important grain growing area in China which experiences serious problems with agricultural nonpoint source pollution (NPS) which is impacting the regional economy and society. In order to address the water quality issues it is necessary to understand the spatial distribution of NPS in the Liao River source area. This issue has been investigated by coupling a wavelet artificial neural network (WA-ANN) precipitation model with a soil and water assessment tool (SWAT) model to assess the export of nonpoint source pollutants from the Liao River source area. The calibration and validation of these models are outlined. The WA-ANN models and the SWAT model were run to generate the spatial distribution of nonpoint source nutrient (nitrogen and phosphorus) exports in the source area of the Liao River. It was found that the SWAT model identified the sub-catchments which not only receive high rainfall but are also densely populated with high agricultural production from dry fields and paddy fields, which are large users of pesticides and chemical fertilizer, as the primary source areas for nutrient exports. It is also concluded that the coupled WA-ANN models and the SWAT model provide a tool which will inform the identification of NPS issues and will facilitate the identification of management practices to improve the water environments in the source area of the Liao River.

Impacts of anthropogenic and natural sources on free tropospheric ozone over the Middle East

Abstract. Significant progress has been made in identifying the influence of different processes and emissions on the summertime enhancements of free tropospheric ozone (O3) at northern midlatitude regions. However, the exact contribution of regional emissions, chemical and transport processes to these summertime enhancements is still not well quantified. Here we focus on quantifying the influence of regional emissions on the summertime O3 enhancements over the Middle East, using updated reactive nitrogen (NOx) emissions. We then use the adjoint of the GEOS-Chem model with these updated NOx emissions to show that the global total contribution of lightning NOx on middle free tropospheric O3 over the Middle East is about 2 times larger than that from global anthropogenic sources. The summertime middle free tropospheric O3 enhancement is primarily due to Asian NOx emissions, with approximately equivalent contributions from Asian anthropogenic activities and lightning. In the Middle Eastern lower free troposphere, lightning NOx from Europe and North America and anthropogenic NOx from Middle Eastern local emissions are the primary sources of O3. This work highlights the critical role of lightning NOx on northern midlatitude free tropospheric O3 and the important effect of the Asian summer monsoon on the export of Asian pollutants.

Factors governing strontium-90 export with surface runoff in the Chernobyl NPP restricted zone

Statistical analysis of collected data revealed priority factors affecting radionuclide migration in water. Considerable changes in the coefficients of correlations between the many-year values of those factors and the water export of 90Sr make it possible to identify the stages associated with a mass passage of primary 90Sr inputs into water-soluble forms. The landscape characteristics of drainage basins were used to construct regression forecast models of the export of pollutants from watersheds.