Factors influencing development of management strategies for the Abou Ali River in Lebanon I: spatial variation and land use

Surface water bodies are progressively subject to increasing stress as a result of environmentally degrading processes primarily related to anthropogenic activities. This study assesses and examines the impact of land use and land-based activities on the spatial variation in water quality of the Abou Ali River in North Lebanon. It is the first detailed study of its kind in Lebanon and adds to the existing knowledge by shedding light on a relatively small Mediterranean river in a developing country where there is a paucity of such studies. The assessment was conducted at the end of the dry season in 2002 and 2003 and the end of the wet season in 2003 and 2004. The study has demonstrated the importance of anthropogenic influences on the water quality of the Abou Ali River Basin, as concentrations of most contaminants were higher at locations with greatest human activity. The most adversely affected area was the section of the river that flows through an entirely urbanized and highly populated region, the Tripoli conurbation. Upstream rural sites were enriched by contaminants primarily from non-point sources such as agricultural runoff and poultry litter whereas contaminant concentrations at the urban sites were enriched by a combination of sewage discharge and flow of contaminants from upstream. If the Abou Ali River is to be utilized as a managed water resource and its water quality sustained, point source discharges will require treatment and land use management must be planned to minimize the impact of diffuse source pollution on the river. A high priority should be given to the implementation and enforcement of the precautionary and polluter pays principles. Moreover, an effective legal, economic and institutional framework is required to encourage investment in waste reduction and control and to introduce environmentally sound practices.     

Water quality and uses of the Bangpakong River (eastern Thailand)

The Bangpakong River is the most important watershed in the Eastern part of Thailand. Water quality parameters were sampled from June 1998 through May 1999 at 11 sites along a 227 km gradient, covering the wet season (June-November) and the dry season (December-May). Surface water was collected at three different stations per site (close to the banks and in the middle of the river), and analyzed for temperature, dissolved oxygen, turbidity, suspended solids, pH. ammonia, fecal coliforms, biochemical oxygen demand and chemical oxygen demand as well as conductivity, phosphate, and heavy metals. The Scottish water quality index (WQI) was adaptated to the tropical environment. The averaged WQI was low (41%) and quality declined significantly during the dry season (ANOVA, p<0.001). Although the quality rose somewhat at middle sites, only 27% of the WQI values during wet season and 2.5% during dry season were higher than 50%, denoting poor environmental quality. Within each season, the main sources of variability were the differences between sites along the gradient (48% during the wet season, 63% during the dry season), whereas monthly variability represented less than 20% of the variability. The seasonal results show that the river is suitable only for tolerant fish and wildlife species and is of doubtful use for potable water supply during the dry season. As quality improves during the wet period, water can be used for the production of potable water, but only with advanced treatment, and for indirect and noncontact recreational activities. In the middle stretches of the river, higher water quality permits multiple uses at moderate cost.     

Tracing the sources of nitrate in the Han River watershed in Korea, using delta15N-NO3- and delta18O-NO3- values

The dissolved nitrate concentrations and their nitrogen and oxygen isotopic ratios were analyzed in seasonal samples from Korea's Han River to ascertain the seasonal and spatial variations of dissolved nitrate and its possible sources. Nitrate concentrations in the South Han River (SHR) were much higher than those in the North Han River (NHR), probably because of the more extensive distribution of agricultural fields, residential areas and animal farms in the SHR drainage basin. The nitrogen isotopic composition of dissolved nitrate indicates that nitrate-nitrogen (NO(3)(-)-N) is derived mainly from atmospheric deposition and/or soil organic matter in the NHR but comes principally from manure or sewage, with only a minor contribution from atmospheric deposition or soil organic matter, in the SHR. The oxygen isotopic compositions of dissolved nitrate suggest that most atmospheric nitrate undergoes microbial nitrification before entering the river.     

Assessment of seasonal variations in surface water quality

Assessment of seasonal changes in surface water quality is an important aspect for evaluating temporal variations of river pollution due to natural or anthropogenic inputs of point and non-point sources. In this study, surface water quality data for 16 physical and chemical parameters collected from 22 monitoring stations in a river during the years from 1998 to 2001 were analyzed. The principal component analysis technique was employed to evaluate the seasonal correlations of water quality parameters, while the principal factor analysis technique was used to extract the parameters that are most important in assessing seasonal variations of river water quality. Analysis shows that a parameter that is most important in contributing to water quality variation for one season may not be important for another season except for DOC and electrical conductance, which were always the most important parameters in contributing to water quality variations for all four seasons.     

A spatial and seasonal assessment of river water chemistry across North West England

This paper presents information on the spatial and seasonal patterns of river water chemistry at approximately 800 sites in North West England based on data from the Environment Agency regional monitoring programme. Within a GIS framework, the linkages between average water chemistry (pH, sulphate, base cations, nutrients and metals) catchment characteristics (topography, land cover, soil hydrology, base flow index and geology), rainfall, deposition chemistry and geo-spatial information on discharge consents (point sources) are examined. Water quality maps reveal that there is a clear distinction between the uplands and lowlands. Upland waters are acidic and have low concentrations of base cations, explained by background geological sources and land cover. Localised high concentrations of metals occur in areas of the Cumbrian Fells which are subjected to mining effluent inputs. Nutrient concentrations are low in the uplands with the exception sites receiving effluent inputs from rural point sources. In the lowlands, both past and present human activities have a major impact on river water chemistry, especially in the urban and industrial heartlands of Greater Manchester, south Lancashire and Merseyside. Over 40% of the sites have average orthophosphate concentrations > 0.1 mg-P l^− 1. Results suggest that the dominant control on orthophosphate concentrations is point source contributions from sewage effluent inputs. Diffuse agricultural sources are also important, although this influence is masked by the impact of point sources. Average nitrate concentrations are linked to the coverage of arable land, although sewage effluent inputs have a significant effect on nitrate concentrations. Metal concentrations in the lowlands are linked to diffuse and point sources. The study demonstrates that point sources, as well as diffuse sources, need to be considered when targeting measures for the effective reduction in river nutrient concentrations. This issue is clearly important with regards to the European Union Water Framework Directive, eutrophication and river water quality.     

The delivery of mercury to the Beaufort Sea of the Arctic Ocean by the Mackenzie River

Very high levels of mercury (Hg) have recently been reported in marine mammals and other higher trophic-level biota in the Mackenzie Delta and Beaufort Sea of the western Arctic Ocean. To quantify the input of Hg (particulate, dissolved and methylated) by the Mackenzie River as a potential source for Hg in the ecosystem, surface water and sediment samples were taken from 79 sites in the lower Mackenzie Basin during three consecutive summers (2003-2005) and analyzed for Hg and methylmercury (MeHg). Intensive studies were also carried out in the Mackenzie Delta during the freshets of 2004 and 2005. Large seasonal and annual variations were found in Hg concentrations in the river, coincident with the variations in water discharge. Increased discharges during spring freshet and during the summers of 2003 and 2005 compared to 2004 were mirrored by higher Hg concentrations. The correlation between Hg concentration and riverflow suggests additional Hg sources during periods of high water, potentially from increased surface inundation and increased bank erosion. The increase in the Hg concentration with increasing water discharge amplifies the annual Hg and MeHg fluxes during high water level years. For the period 2003-2005, the Hg and MeHg fluxes from the Mackenzie River to the Beaufort Sea averaged 2.2 tonnes/yr and 15 kg/yr, respectively, the largest known Hg source to the Beaufort Sea. More than half of the mercury flux occurs during the short spring freshet season which coincides with the period of rapid growth of marine biota. Consequently, the Mackenzie River input potentially provides the major mercury source to marine mammals of the Beaufort Sea. The Hg and MeHg fluxes from the Mackenzie River are expected to further increase with the projected climate warming in the Mackenzie Basin.     

Sewage-effluent phosphorus: a greater risk to river eutrophication than agricultural phosphorus?

Phosphorus (P) concentrations from water quality monitoring at 54 UK river sites across seven major lowland catchment systems are examined in relation to eutrophication risk and to the relative importance of point and diffuse sources. The over-riding evidence indicates that point (effluent) rather than diffuse (agricultural) sources of phosphorus provide the most significant risk for river eutrophication, even in rural areas with high agricultural phosphorus losses. Traditionally, the relative importance of point and diffuse sources has been assessed from annual P flux budgets, which are often dominated by diffuse inputs in storm runoff from intensively managed agricultural land. However, the ecological risk associated with nuisance algal growth in rivers is largely linked to soluble reactive phosphorus (SRP) concentrations during times of ecological sensitivity (spring/summer low-flow periods), when biological activity is at its highest. The relationships between SRP and total phosphorus (TP; total dissolved P+suspended particulate P) concentrations within UK rivers are evaluated in relation to flow and boron (B; a tracer of sewage effluent). SRP is the dominant P fraction (average 67% of TP) in all of the rivers monitored, with higher percentages at low flows. In most of the rivers the highest SRP concentrations occur under low-flow conditions and SRP concentrations are diluted as flows increase, which is indicative of point, rather than diffuse, sources. Strong positive correlations between SRP and B (also TP and B) across all the 54 river monitoring sites also confirm the primary importance of point source controls of phosphorus concentrations in these rivers, particularly during spring and summer low flows, which are times of greatest eutrophication risk. Particulate phosphorus (PP) may form a significant proportion of the phosphorus load to rivers, particularly during winter storm events, but this is of questionable relevance for river eutrophication. Although some of the agriculturally derived PP is retained as sediment on the river bed, in most cases this bed sediment showed potential for removal of SRP from the overlying river water during spring and summer low flows. Thus, bed sediments may well be helping to reduce SRP concentrations within the river at times of eutrophication risk. These findings have important implications for targeting environmental management controls for phosphorus more efficiently, in relation to the European Union Water Framework Directive requirements to maintain/improve the ecological quality of impacted lowland rivers. For the UK rivers examined here, our results demonstrate that an important starting point for reducing phosphorus concentrations to the levels approaching those required for ecological improvement, is to obtain better control over point source inputs, particularly small point sources discharging to ecologically sensitive rural/agricultural tributaries.     

大汶河梯级拦蓄水库富营养化评估

基于大汶河沿线4个监测点2007—2014年水质资料,分析溶解氧、化学需氧量、氨氮等9项指标的年际变化特征,采用灰色模式识别模型评价大汶河水质状况。通过9个梯级水库2015年丰、平、枯水期水质现场调查,分析氮、磷营养盐时空变化特征,运用加权综合营养状态指数法评价梯级水库营养状态。结果表明:2007—2014年间,受流域内各项减排措施影响,大汶河有机污染得到有效缓解;受拦蓄工程影响,河段内TP明显变优,TN总体变差;灰色综合指数表明,水质状况整体有所好转,且季节波动趋于平稳。因污染程度不同,梯级水库富营养化状态有明显差异,部分库区丰水期和枯水期已分别爆发蓝藻和硅藻水华,不同水期因下泄流量不同等造成流动条件的差异,对库区水质有较大影响,水污染程度、工程拦蓄与运行造成的流动条件差异共同对库区内藻类生长与爆发产生重要影响。     

Seasonal first flush phenomenon of urban stormwater discharges

California's climate, typified by winter and spring precipitation and summer drought, is often called a Mediterranean climate, and creates a long period for pollutant build-up. The initial storms of the winter season usually have higher pollutant concentrations, which is called a seasonal first flush. To investigate the existence of a seasonal first flush, we analyzed four major data sets, collected over the 1999-2000 to 2002-2003 wet seasons. Trends in seasonal loads were quantified by plotting pollutant concentrations or cumulative pollutant load versus cumulative rainfall or cumulative runoff volume. Pollutant concentrations in the first part of the wet season were ranged from 1.2 to 20 times higher than concentrations near the end of the season, and mass emission rates were similarly higher at the beginning of the season. A seasonal first flush existed for most cases and was strongest for organics, minerals and heavy metals except lead. This result suggests that applying treatment Best Management Practices (BMPs) early in the season could remove several times more pollutant mass than randomly timed or uniformly applied BMPs.     

Impact of geochemical stressors on shallow groundwater quality

Groundwater monitoring wells (about 70 wells) were extensively installed in 28 sites surrounding Lake Texoma, located on the border of Oklahoma and Texas, to assess the impact of geochemical stressors to shallow groundwater quality. The monitoring wells were classified into three groups (residential area, agricultural area, and oil field area) depending on their land uses. During a 2-year period from 1999 to 2001 the monitoring wells were sampled every 3 months on a seasonal basis. Water quality assay consisted of 25 parameters including field parameters, nutrients, major ions, and trace elements. Occurrence and level of inorganics in groundwater samples were related to the land use and temporal change. Groundwater of the agricultural area showed lower levels of ferrous iron and nitrate than the residential area. The summer season data revealed more distinct differences in inorganic profiles of the two land use groundwater samples. There is a possible trend that nitrate concentrations in groundwater increased as the proportions of cultivated area increased. Water-soluble ferrous iron occurred primarily in water samples with a low dissolved oxygen concentration and/or a negative redox potential. The presence of brine waste in shallow groundwater was detected by chloride and conductivity in oil field area. Dissolved trace metals and volatile organic carbons were not in a form of concentration to be stressors. This study showed that the quality of shallow ground water could be related to regional geochemical stressors surrounding the lake.     

Assessing the improvement of the Bilbao estuary water quality in response to pollution abatement measures

To evaluate the success of almost 20 years of pollution abatement in the Bilbao estuary watershed in northern Spain, we analyzed temporal trends in pollution discharges and water quality from 1993 to 2003. Over that period a great portion of the raw wastewater discharge was intercepted and treated, leading to a significant reduction in the pollution load to the estuary (51.8% in biochemical oxygen demand, 70.9% in ammonia nitrogen and 81.9% in faecal coliforms). Temporal trends of mean annual levels of water quality variables showed statistically significant increases in dissolved oxygen saturation (between 2.04 and 4.11%/year) and decreases in ammonia nitrogen (between -4.15 and -175.75 microM NH3/year) and faecal coliforms concentrations (from 2.55 x 10(5) to 2.13 x 10(4) CFU/100ml). The improvement of the Bilbao estuary water quality reported in this paper is primarily attributed to the pollution abatement measures accomplished by the local water authority. Finally, as a result of these pollution control efforts, European bathing water quality standards were met at local beaches.     

Stormwater impact on water quality of rivers subjected to point sources and urbanization – the case of Addis Ababa,Ethiopia

Urbanization of a catchment often causes degeneration of rivers. We studied the water quality of three rivers in Addis Ababa based on the impact of stormwater and non‐point sources, and urbanization. Along these rivers several point sources were registered, with direct discharge of industrial and domestic wastes into them. To distinguish the impact of these year‐round point‐sources from stormwater, we analysed physicochemical parameters, nutrients and heavy metals sampled from upstream to downstream sections of each river in the dry and wet season. Dissolved oxygen (DO), NO₂–N, NH₄–N, PO₄–P, (Cr(VI) and Cu) exceeded international standards, pointing to a generally poor water quality of the rivers in both seasons. NO₃–N, Mn and Zn were problematic in dry season only. Although stormwater improved DO, conductivity, PO₄–P, Cr(VI) and Zn, the levels were still critical, pointing to construction sites, agriculture and pit latrines, somewhat offsetting the effect of stormwater dilution. No clear impact of urbanization pressure was found.     

Orthophosphate Concentrations in the River Thames

Observed concentrations of orthophosphate in the River Thames, from its source to its tidal limit, exceed 0.1 mg P/1 for most of its length; reasons for annual and seasonal variations are explained. By using data routinely collected by the Environment Agency throughout the Thames catchment, the orthophosphate load in the river, derived from agricultural sources and sewage-treatment works, is estimated.
A water quality model, TOMCAT, has been adapted to simulate observed data and used to estimate river concentrations if orthophosphate loads from sewage-treatment works are reduced.     

Nitrogen pollution and source identification in the Haicheng River basin in Northeast China

A survey was conducted in the Haicheng River near Liaodong Bay to analyze the characteristics and sources of the in-stream nitrogen pollution throughout the year 2010. The results indicated that the total nitrogen (TN) concentrations in the river water all exceeded the GB3838-2002 standard for Class V guideline of 2.0 mg/l at all sampling sites during the sampling seasons. Ammoniacal nitrogen (NH₃-N) dominated TN during the spring season, while nitrate nitrogen (NO₃-N) dominated during the summer and autumn seasons. Different forms of nitrogen had significant seasonal variations (p < 0.01 or p < 0.05). Only NH₃-N and NO₃-N displayed distinct spatial differences at p < 0.05 and p < 0.001, respectively. Most forms of nitrogen were interrelated with physicochemical parameters during different seasons, displaying nitrification and denitrification processes that occurred in the river rather than seasonal biological demand. Based on the nitrogen parameters, the 30 sampling sites were divided into three clusters, by which the pollution sources from chemical nitrogen fertilizers, animal wastes, domestic sewage, and industrial wastewater were identified. Generally, the Haicheng River basin provided about 700 tons of the annual TN flux, contributing to the eutrophication of the Liaodong Bay and Bohai Sea.     

Water quality index as a simple indicator of watersheds pollution in southwestern part of Iran

The Karun River is the most important watershed in the southwestern region of Iran. Water quality parameters were sampled from October 2006 through July 2007 at three sites along a 4 km gradient, covering both the wet and the dry season. Surface water was collected at three different stations per site (close to the banks and in the middle of the river) and analysed for 14 parameters and heavy metals. The values of 1300, 196.8 and 4042.9 ppm for chemical oxygen demand, biochemical oxygen demand and chloride, respectively, were higher than the standards limits. water quality index (WQI) values were very useful for the classification of the waters monitored. The averaged WQI was low (47%), and quality declined significantly during the dry season [analysis of variance (ANOVA, P < 0.05)]. The annual WQI values of 54.60, 40.29 and 45.71 from sites 1, 2 and 3 correspond to medium, bad and bad water qualities, respectively.     

Dynamics of CO2 partial pressure and CO2 outgassing in the lower reaches of the Xijiang River, a subtropical monsoon river in China

The partial pressure of carbon dioxide (pCO(2)) in surface water was surveyed monthly at 6 sampling sites along the entire length of the lower reaches of the Xijiang River, a subtropical monsoon river in China, and at the mouths of its major tributaries, over a whole hydrological year from April 2005 to March 2006, to reveal the seasonal and spatial dynamics of pCO(2). Intensive sampling and measurements were also conducted at Wuzhou gauge station in June and July to investigate the impact of floodwater on pCO(2) and to further explore the relationship between river discharge and pCO(2). The pCO(2) levels were well above atmospheric equilibrium (380 microatm) during the entire survey period with obvious seasonal and spatial variations, ranging from 600 microatm to 7200 microatm for the mainstream and from 700 to 11000 microatm for tributaries, respectively. The pattern of pCO(2) seasonal variation across 6 sites was almost consistent with each other with little difference. The pCO(2) levels in the dry season were relatively low, with relatively slight temporal and spatial fluctuations that were predominantly controlled by in situ biogenic activities. While the pCO(2) in the wet season greatly varied with river discharge, both annual maximum and minimum pCO(2) levels occurring in this period. The much higher pCO(2) in the early wet season were mainly induced by increasing baseflow and interflow that flushed significant soil CO(2) into the streams, whereas the lower pCO(2) observed after floods from July to September, some even lower than pCO(2) levels in the dry season, potentially resulted from in situ plankton blooms. The annual minima pCO(2) levels occurring in this period were caused by the dilution effect of floodwater. There was no obvious downstream trend in pCO(2) variation during the whole survey period, probably a consequence of disturbance from tributaries or spatially distinct channel characteristics and water environments. Based on measurements, we estimate that the water-to-air CO(2) flux in the lower reaches of the Xijiang River is about 8.3-15.6 Mg C ha(-1)y(-1). The role of the Xijiang River as a net source of atmospheric CO(2) is undoubted.     

Recent trends in nutrient concentrations in Swedish agricultural rivers

In five out of twelve Swedish agricultural rivers examined during the period 1993-2004, significant trends for decreasing concentrations of reactive inorganic nitrogen (RIN) were indicated after flow normalisation. These decreases were constant (equal to 2-4% per year), most apparent in the Scania region, and weakly correlated to reductions in livestock density (Pearson correlation coefficient -0.825). The number of grazing cattle livestock units per unit area of arable land decreased on average by 14% and that of non-grazing cattle by 17% during 1985-2003. Based on estimates of root-zone leaching, increased area of set-aside and recent EU subsidisation of catch crops (with/without spring tillage) were suggested to be additional substantial causes but these changes were only rapid very recently (years 2000-2001). A significant and constant decrease in reactive phosphorus (RP) (3% per year) was observed in one river, mainly during the season of low flow, with reduced load from point sources suggested to be the main reason. Significant and constant reductions equal to 3-8% per year in concentrations of non-reactive phosphorus (NRP) were calculated for five rivers. These improvements were weakly correlated to the length of grassed buffer zones along the watercourses in arable parts of the river basin (Pearson correlation coefficient -0.845). Establishment of such zones also took place more recently, and together with constructed wetlands represent on average 0.5% of the agricultural area.     

The effect of a wildfire on stream water quality and catchment water yield in a tropical savanna excluded from fire for 10 years (Kakadu National Park, North Australia)

The wet/dry tropics of the Australian savannas are particularly prone to fire due to the highly seasonal rainfall and accumulation of grassy fuels. The effect of an early dry season wildfire (May, 1998) on the water quality of a seasonally flowing stream (December-June) was examined for a lowland savanna forest in Kakadu National Park (northern Australia) which had remained unburnt for 10 years. The water quality variables assessed were: total and volatile suspended sediment, phosphorus, nitrogen, iron and manganese. Compared to three years of pre-fire water quality data and 5 years of stream flow data, there was no detectable impact of the wildfire on the volume of stream flow, mean concentrations and the total mass transported by the stream for each water quality variable, except possibly nitrogen. The limited effect on water quality is attributed primarily to the timing of the wildfire and the low intensity relative to fires later in the dry season (September). The retention of canopy cover and the accumulation of leaf litter following the wildfire, and the catchment's gently undulating terrain all contributed to the negligible impact on water quality. Early dry season fires appear to be a viable management option for reducing accumulated fuel loads and hence reducing the risk of destructive wildfires later in the dry season.     

Modeling the contribution of point sources and non-point sources to Thachin River water pollution

Major rivers in developing and emerging countries suffer increasingly of severe degradation of water quality. The current study uses a mathematical Material Flow Analysis (MMFA) as a complementary approach to address the degradation of river water quality due to nutrient pollution in the Thachin River Basin in Central Thailand. This paper gives an overview of the origins and flow paths of the various point- and non-point pollution sources in the Thachin River Basin (in terms of nitrogen and phosphorus) and quantifies their relative importance within the system. The key parameters influencing the main nutrient flows are determined and possible mitigation measures discussed.The results show that aquaculture (as a point source) and rice farming (as a non-point source) are the key nutrient sources in the Thachin River Basin. Other point sources such as pig farms, households and industries, which were previously cited as the most relevant pollution sources in terms of organic pollution, play less significant roles in comparison. This order of importance shifts when considering the model results for the provincial level. Crosschecks with secondary data and field studies confirm the plausibility of our simulations. Specific nutrient loads for the pollution sources are derived; these can be used for a first broad quantification of nutrient pollution in comparable river basins. Based on an identification of the sensitive model parameters, possible mitigation scenarios are determined and their potential to reduce the nutrient load evaluated.A comparison of simulated nutrient loads with measured nutrient concentrations shows that nutrient retention in the river system may be significant. Sedimentation in the slow flowing surface water network as well as nitrogen emission to the air from the warm oxygen deficient waters are certainly partly responsible, but also wetlands along the river banks could play an important role as nutrient sinks.     

Dissolved silicon in a North Wales catchment of high relief

Concentrations of dissolved silicon and nitrogen in the Afon Anafon, a river draining the mountainous region of North Wales, were monitored over an annual cycle. As a result of the high relief the silicon concentration in the baseflow was diluted by surface flow and interflow. This led to low silicon concentrations in the river water (maximum 1540 μg l^?1, minimum < 100 μg l^?1) an inverse relationship between silicon concentration and discharge and a low removal rate of silicon by dissolution from the catchment (0.07 mg SiO₂ cm^?2 yr^?1). Nitrate concentrations, in contrast, showed a typical seasonal variation and were less affected by variations in the discharge.