Characteristics of and Human Influences on Nitrogen Contamination in Yellow River System, China

Nitrogen (N) contamination in the Yellow River mainstream and its tributaries was studied using data from 1960 to 2000 from 312 monitoring sites in the Yellow River system. Data showed that N concentrations in the Yellow River have increased since 1960, especially after 1990. N concentrations in the Yellow River mainstream increased from the upper reaches (less than 1.0 mg L(-1) for TN and less than 0.10 mg L(-1) for NH4(+)-N) to lower reaches (higher than 4-5 mg L(-1) for TN and higher than 1.0 mg L(-1) for NH4(+)-N). However, the highest N contaminations (50-250 mg L(-1) for TN and 10-20 mg L(-1) for NH4(+)-N) was found in some tributaries, which was attributed as an effect of industrial wastewater and municipal sewage. Nitrogen concentrations from several monitoring sites were positively correlated with several regional socio-economic indices, such as population density, fertilization rates, livestock, industrial input and GDP. Depending on location, seasonal N concentrations contrasted among watersheds. Monitoring stations located in rural and agricultural areas showed higher N concentrations during the flood season while those located in areas with urban and industrial centers showed higher N concentration during the dry season. Mainstream flow and N concentrations showed a strong inverse relationship; with higher N concentrations as the river flow declined. Intensive water extraction for agricultural irrigation and increasing N input to the river from fertilized agricultural fields could explain the increasing N concentrations during extensive droughts.     

Monitoring terbutryn pollution in small rivers of Hesse, Germany

Four small river systems in Hesse, Germany, were investigated with respect to seasonal and spatial concentrations of the herbicide terbutryn [2-(t-butylamino)-4-(ethylamino)-6-(methylthio)-s-triazine]. Despite introduction of a ban on its use as a herbicide in July 2003, terbutryn was still present in the rivers during the whole sampling period from September 2003 to September 2006, and there was no trend of decreasing concentration during this time. In the Weschnitz and Modau river systems the mean terbutryn concentration exceeded the German drinking water ordinance threshold value for single biocides. Maximum concentrations of up to 5.6 microg l(-1) were determined in the Weschnitz River. Higher terbutryn concentrations in summer are suggested to originate from agricultural sources, as well as from sediment redissolution. Effluents of two sewage treatment plants had high terbutryn concentrations, indicating that terbutryn enters the rivers from this source. Sources other than agriculture must explain terbutryn occurrence in the rivers during winter, when farm pesticide application typically ceases. The potential for mobilization of terbutryn from sediments and leaching from soils are discussed.     

Temporal and Spatial Variation of Nutrient Levels in the Nemunas River (Lithuania and Belarus)

There are discordant results on trends in nutrient river water quality from the economical transition countries in Europe. The present study assessed the impact of these economical changes on the load and concentration at 17 monitoring stations along the Nemunas River and its major tributaries (Lithuania and Belarus). Three time periods were evaluated: the Soviet rule command system period 1986–1991, the transfer to market economy period 1992–1996 and the post reform period 1997–2002. The most surprising result in this study, was the increased area-specific load of NO₃-N from the first to the third period at almost all the sampling sites. The increase was particularly large (43–78%) at the sites in the Lithuanian part of the river. The corresponding load increase in the Belarussian part of the river was only 1–15%. The statistical analyses of concentration data confirm the strong upward NO₃-N trend at the Nemunas mouth and at 5 of the 6 tributaries in the lower part of Nemunas. Temporal and spatial analysis of nitrates transport in the Nemunas River and its main tributaries revealed that nitrates mainly originate from agricultural areas. The upward trends were most likely an effect of ploughing of pastures and unbalanced crop fertilisation in combination with large storage and accumulation of soil-nitrogen during the Soviet period.On contrary to nitrate-N, the area-specific load of PO₄-P decreased significantly from the first to the third period at all sites along the Nemunas River (31–86%). Seasonal (SMK) and Partial (PMK) Mann-Kendall tests on PO₄-P concentrations also showed significant downward trend at 14 of 16 investigated sites. The decrease of PO₄-P levels was attributed to the reduction of municipal and industrial point source emissions and to the decreased livestock numbers.The NH₄-N load showed the same pattern as PO₄-P. At the river mouth the load was 90 kg km⁻² yr⁻¹ during the first period compared to only 20–30 kg km⁻² yr⁻¹ in the third period. The trend test on NH₄-N concentrations detected significant downward trends at 5 out of 16 sites. The declines were explained by decreased emissions from cities and large animal breeding farms.This study showed that trend analysis at multiple sites in a river basin is crucial for the understanding of the variability in time and space. Such analysis is also important for our interpretation of underlying sources and fluxes in a drainage basin over time. This is particularly important for compounds that have different source origin.     

Atmospheric wet deposition of soluble macro-nutrients in the Cilician Basin, north-eastern Mediterranean sea

In order to estimate wet deposition atmospheric fluxes of macro-nutrients into the eastern Mediterranean coastal waters, soluble inorganic phosphate (PO4(3-)), nitrate (NO3-) and nitrite (NO2-) concentrations in precipitation (from February 1996 to June 1997) have been measured at a coastal sampling site, Erdemli, Turkey. Water-soluble inorganic PO4(3)-P, a reactive, bioavailable, limiting macro-nutrient in the oligotrophic waters of the eastern Mediterranean was studied with respect to its contribution to biological productivity. Reactive PO4(3-)-P and NO2(-) + NO3(-)-N concentrations were found to be highly variable in rainwater samples. One of the aims of the study was to determine the contribution of dust transport to the soluble macro-nutrient budget of the eastern Mediterranean. No differences were found between the mean reactive P and NO(2-) + NO3(-)-N concentrations of "red rain" and normal rain events. Most likely as a result of low solubility of crustal phosphorus, dust episodes were not found to be important sources of reactive P, in terms of wet deposition. The annual wet deposition fluxes of reactive PO4(3-)-P and NO2(-) + NO3(-)-N into the Cilician Basin were respectively estimated to be 0.010 g P m(-2) per year and 0.23 g N m(-2) per year, which are comparable to the fluxes from land-based sources in the north-eastern Mediterranean. The incorporation of water soluble bioavailable PO4(3-)-P and NO2(-) + NO3(-)-N delivered via atmospheric wet deposition could be responsible for approximately 3.3% (0.40 g C m(-2) per year) and 11.0% (1.31 g C m(-2) per year) respectively, of the mean annual new production in the north-eastern Mediterranean.     

Chemical trends in background air quality and the ionic composition of precipitation for the period 1980-2004 from samples collected at Valentia Observatory, Co. Kerry, Ireland

A major Irish study, based upon more than 8000 samples collected over the measurement period of 22 years, for sulfur dioxide (SO2-S), sulfate (SO4-S) and nitrogen dioxide (NO2-N) concentrations (microg m(-3)) within air, and the ionic composition of precipitation samples based on sodium (Na+), potassium (K+), magnesium (Mg2+), calcium (Ca2+), chloride (Cl-), sulfate (SO4-S), non-sea salt sulfate (nssSO4-S), ammonium (NH4-N), and nitrate (NO3-N) weighted mean concentrations (mg l(-1)), has been completed. For the air samples, the sulfur dioxide and sulfate concentrations decreased over the sampling period (1980-2004) by 75% and 45%, respectively, whereas no significant trend was observed for nitrogen dioxide. The highest concentrations for sulfur dioxide, sulfate and nitrogen dioxide were associated with wind originating from the easterly and northeasterly directions i.e. those influenced by Irish and European sources. The lowest concentrations were associated with the westerly directions i.e. for air masses originating in the North Atlantic region. This was further verified with the use of backward (back) trajectory analysis, which allowed tracing the movement of air parcels using the European Centre for Medium range Weather Forecasting (ECMWF) ERA-40 re-analysis data. High non-sea salt sulfate levels were being associated with air masses originating from Europe (easterlies) with lower levels from the Atlantic (westerlies). With the precipitation data, analysis of the non-sea salt sulfate concentrations showed a decrease by 47% since the measurements commenced.     

Long-term relationships between SO2 and NOx emissions and SO4(2-) and NO3- concentration in bulk deposition at the Hubbard Brook Experimental Forest, NH

A highly significant second-order polynomial relation between SO(2) emissions and SO(4)(2-) concentrations during 1970-2000 (r(2)= 0.80, p= <0.001), and a linear relation between NO(x) and NO(3)(-) concentrations during 1991-2000 (r(2)= 0.67, p= 0.004) in bulk precipitation were found for the Hubbard Brook Experimental Forest, NH based on emissions from a 24 h, back-trajectory determined source area. Earlier periods (1965-1980) for SO(2)ratio SO(4)(2-) and longer periods (1965-2000) for NO(x)ratio NO(3)(-) had poorer linear relations, r(2)= 0.03, p= 0.51 and r(2)= 0.22, p= 0.004, respectively. Methodology by the US Environmental Protection Agency for calculating emissions data during this period has changed significantly and frequently, making trend analysis difficult. Given the large potential for errors in estimating emissions and to a lesser extent, deposition, the robust relations between SO(2) emissions and SO(4)(2-) concentrations in bulk precipitation at the Hubbard Brook Experimental Forest show that careful, long-term measurements from a single monitoring site can provide sound and reasonable data on trends in air pollution.     

Temporal and spatial variations of nutrients in the Ten Mile Creek of South Florida, USA and effects on phytoplankton biomass

Water quality throughout south Florida has been a major concern for many years. Nutrient enrichment in the Indian River Lagoon (IRL) is a major surface water issue and is suggested as a possible cause of symptoms of ecological degradation. In 2005-06, water samples were collected weekly from seven sites along Ten Mile Creek (TMC), which drains into the Indian River Lagoon, to investigate and analyze spatial and temporal fluctuations of nutrients nitrogen (N) and phosphorus (P). The objective of this study was to understand the relationships among chlorophyll a concentration, nutrient enrichment and hydrological parameters in the surface water body.High median concentrations of total P (TP, 0.272 mg L(-1)), PO4-P (0.122 mg L(-1)), and dissolved total P (DTP, 0.179 mg L(-1)); and total N (TN, 0.988 mg L(-1)), NO3(-)-N (0.104 mg L(-1)), NH4+-N (0.103 mg L(-1)), and total Kjeldahl N (TKN, 0.829 mg L(-1)), were measured in TMC. The concentrations of TP, PO4-P, DTP, TN, NO3(-)-N, NH4+-N, and TKN were higher in summer and fall than in winter and spring. However, chlorophyll a and pheophytin concentrations during this period in TMC varied in the range of 0.000-60.7 and 0.000-17.4 microg L(-1), with their median values of 3.54 and 3.02 microg L(-1), respectively. The greatest mean chlorophyll a (10.3 microg L(-1)) and pheophytin (5.71 microg L(-1)) concentrations occurred in spring, while the lowest chlorophyll a (1.49 microg L(-1)) and pheophytin (1.97 mug L(-1)) in fall. High concentrations of PO4-P (>0.16 mg L(-1)), DTP (>0.24 mg L(-1)), NO3(-)-N (>0.15 mg L(-1)), NH4+-N (>0.12 mg L(-1)), and TKN (>0.96 mg L(-1)), occurred in the upstream of TMC, while high concentrations of chlorophyll a (>6.8 mug L(-l)) and pheophytin (>3.9 microg L(-l)) were detected in the downstream of TMC. The highest chlorophyll a (11.8 mug L(-l)) and pheophytin (6.06 microg L(-l)) concentrations, however, were associated with static and open water conditions. Hydrological parameters (total dissolved solid, electrical conductivity, salinity, pH, and water temperature) were positively correlated with chlorophyll a and pheophytin concentrations (P < 0.01) and these factors overshadowed the relationships between N and P concentrations and chlorophyll a under field conditions. Principal component analysis and the ratios of DIN/DP and TN/TP in the water suggest that N is the limiting nutrient factor for phytoplankton growth in the TMC and elevated N relative to P is beneficial to the growth of phytoplankton, which is supported by laboratory culture experiments under controlled conditions.     

Spatial and temporal variations of nitrogen pollution in Wen-Rui Tang River watershed, Zhejiang, China

Water quality has degraded dramatically in Wen-Rui Tang River watershed, Zhejiang, China, especially due to rapid economic development since 1995. This paper aims to assess spatial and temporal variations of the main pollutants (NH??-N, TN, BOD(5), COD(Mn), DO) of water quality in Wen-Rui Tang River watershed, using the geographic information system, cluster analysis (CA) and principal component analysis (PCA). Results showed that concentrations of BOD(5), COD(Mn), NH??-N, and TN were significantly higher in tertiary rivers than in primary and secondary rivers. From April 2006 to March 2007, the concentrations of NH? ?-N (2.25-57.9 mg/L) and TN (3.78-70.4 mg/L) in all samples exceeded Type V national water quality standards (≥2 mg/L), while 5.3% of all COD(Mn) (1.83-27.5 mg/L) and 33.6% of all BOD(5) (0.34-50.4 mg/L) samples exceeded Type V national water quality standards (COD(Mn)?≥ 15 mg/L, BOD(5)?≥ 10 mg/L). Monthly changes of pollutant concentrations did not show a clear pattern, but correlation analysis indicated that NH??-N and TN in tertiary rivers had a significant negative correlation with 5-day cumulative rainfall and monthly rainfall, while there were no significant correlations in primary and secondary rivers. The results of CA and spatial analysis showed that the northern part of Wen-Rui Tang River watershed was the most seriously polluted. This region is characterized by the high population density and industrial and commercial activities. The PCA and spatial analysis indicated that the degraded water quality is caused by anthropogenic activities and poor wastewater management.     

大连市中心城区地下水“三氮”污染分析

依据《地下水质量标准》(GB/T 14848-1993),对大连市中心城区2006-2010年地下水"三氮"监测资料进行分析。结果表明,"三氮"的检出率(最高为100%)和超标率(最高为58.8%)都较高,其中亚硝酸盐氮超标显著。氨氮浓度各年均值均超标,呈波动变化;亚硝酸盐氮浓度各年均值均超标,并呈上升趋势;硝酸盐氮各年均值波动变化,总体呈上升趋势。除2009年以外,其他4年中丰水期的硝酸盐氮浓度都比枯水期高;除2007年外,其他4年中的丰水期氨氮浓度都比枯水期低。"三氮"最高浓度值主要出现在中心城区周边区域。     

Spatial distribution of inorganic nitrogen contents of marsh soils in a river floodplain with different flood frequencies from soil-defrozen period

Contents of inorganic nitrogen (NH4(+)-N and NO3(-)-N) in soil profiles were measured in five typical zones ( including permanently flooded floodplain(B), 1-year floodplain (O), 5-year floodplain (F),10-year floodplain (T), and 100-year floodplain (H) )from Huolin River floodplain in Erbaifangzi, Jilin Province of China, in the soil-defrosted period (Mayof 1999). Contour maps and profile maps were constructed to describe the spatial distributions of NH4(+)-N and NO3(-)-N) in order to identify the influences of flood frequencies on them. Results showed that NH4(+)-N generally increased with depth in soil profiles from the five areas, but NH4(+)-N contents in T or H areas significantly differed from those in other areas. For NO3(-)-N, with the exception that there was a significant cumulative peak (6.77 +/- 0.08 mg kg(-1)) at 15-cm depth (10-20 cm) in B area, no significant difference was observed between NO3(-)-N contents in soil profiles from the other four areas. The horizontal distributions of NH4(+)-N and NO3(-)-N in top soils (0-10 cm) were different in the five areas,which were greatly influenced by flood frequencies. The highest content of NH4(+)-N or NO3(-)-N did not appear in B area but in the floodplain with certain flood frequency. For example, NH4(+)-N content (16.81 mg kg-(1)) in 5-year floodplain wetland was highest, and the highest content of NO3(-)-N(1.69 mg kg(-1)) appeared in 1-year floodplain wetland. In addition, NH4(+)-N contents were significantly correlated with soil pH, and NO3(-)-N contents had significant correlation with inorganic carbon, but there were no significant correlations between inorganic nitrogen and other selected soil properties.     

土地利用景观格局对信江水质的影响

利用GIS空间分析与统计方法,从景观尺度和类型尺度两方面分析了流域景观格局空间分异对河流高锰酸盐指数(CODMn)、氨氮、总氮(TN)、化学需氧量(CODCr)的影响。信江流域的景观组成对CODMn、氨氮、TN、CODCr浓度存在显著影响,耕地和建设用地的面积比例与各项指标浓度间存在显著正相关,林地与各指标浓度存在显著负相关。各项指标在流域上游变化不大,而在流域的下游变化显著。从景观尺度上看,流域景观以少数大斑块为主或同一类型的斑块高度连接时,河流中CODMn、氨氮、TN、CODCr浓度较低,水质较好。从流域类型尺度上看,各类型的景观结构对河流中CODMn、氨氮、TN、CODCr浓度影响不同,建设用地以及耕地的集中大面积彼此相临的连片分布会导致河流中CODMn、氨氮、TN、CODCr等浓度的升高,而林地则表现出相反的效应。     

Nitrate leaching to shallow groundwater systems from agricultural fields with different management practices

Monitoring the concentration of NO(3)-N from agricultural fields to the subsurface and shallow ground water resources have received considerable interest worldwide, since agriculture has been identified as a major source of nitrate-nitrogen (NO(3)-N) pollution of groundwater systems in intensively farmed watersheds. A study was conducted to quantify the impact of two tillage practices viz. chisel plow (CP) and no till (NT) with liquid swine manure application on nitrate leaching to the shallow ground water system under corn-soybean production system. This study is part of the long-term field experiments conducted at Iowa State University using completely randomized block design. The NO(3)-N concentrations in the shallow ground water were monitored at three depths viz., a network of subsurface drains at a depth of 1.2 m and piezometers at depths of 1.8 m and 2.4 m. Results of this study showed that the average NO(3)-N concentration during the study period was 16.1 mg l(-1), 14.4 mg l(-1) and 11.8 mg l(-1) at 1.2 m, 1.8 m and 2.4 m depths, respectively implying significant amount of NO(3)-N leaching past the subsurface drain depth of 1.2 m into the shallow groundwater but the NO(3)-N concentration decreases with the depth. The NO(3)-N concentrations in shallow groundwater were significantly higher under the chisel plow system in comparison with the no till method of tillage. Fall application of liquid swine manure caused more leaching in comparison with the spring application. Higher NO(3)-N concentration was observed under corn in comparison with the soybean plots. An in-depth analysis of the data showed a definite relationship between the NO(3)-N concentration in subsurface drain water at a depth of 1.2 m and shallow groundwater at depths of 1.8 m and 2.4 m depths.     

Statistical approaches for hydrogeochemical characterization of groundwater in West Delhi, India

Parametric statistical approaches, correlations and multiple linear regressions were used to develop models for the interpretation of hydrogeochemical parameters in the Western part of Delhi state, India. The hydrogeochemical parameters indicated that the groundwater quality is not safe for consumption. The water is moderately saline and the salinity level is increasing over time. There is also the problem of nitrate pollution. The correlation between electrical conductivity (EC) and other water quality parameters except potassium (K(+)), nitrate (NO(3)(-)) and bicarbonate (HCO(3)(-)) is significantly positive and Ca(++)+ Mg(++)/Na(+)+ K(+) is significantly negative. In predicting EC, the multiple R(2) values of 0.996 and 0.985 indicate that 99.6% and 98.5% variability in the observed EC could be ascribed to the combined effect of Na(+), HCO(3)(-), Cl(-), SO(4)(--), NO(3)(-) and Ca(++)+ Mg(++) for the year of 2005 and 2006 respectively. Out of 99.6% of the variability in EC in 2005, 51.2% was due to Cl(-) alone, and 8.5%, 12.5%, 6.1%, 14.7% and 6.7% were due to Na(+), HCO(3)(-), SO(4)(--), NO(3)(-) and Ca(++) + Mg(++). Similarly in 2006, out of 98.5% of the variability in EC, 48.5% was due to Cl(-) alone, and 10.4%, 12.7%, 5.3%, 17.2% and 4.4% were due to Na(+), HCO(3)(-), SO(4)(--), NO(3)(-) and Ca(++)+ Mg(++). The analysis shows that a good correlation exists between EC, Cl(-) and SO(4)(--) either individually or in combination with other ions and the multiple regression models can predict EC at 5% level of significance.     

Contemporary estimates of atmospheric nitrogen deposition to the watersheds of New York State, USA

Atmospheric inputs of reactive nitrogen (N) to ecosystems are a particular concern in the northeastern USA, including New York State, where rates of atmospheric N deposition are among the highest in the nation. We calculate the seasonal and annual spatial variations of contemporary inorganic atmospheric N deposition loading to multi-scale watersheds across New York State using numerous monitoring datasets of precipitation and ambient atmospheric N concentrations. Our models build upon and refine previous efforts estimating the spatial distribution of N deposition. Estimates of total inorganic wet deposition (NH4-N + NO3-N) across New York ranged from 4.7 to 10.5 kg ha(-1) yr(-1) under contemporary conditions (averaged 2002-2004), and both seasonal and annual predicted rates of inorganic N deposition (NH4-N, NO3-N, and total) fit relatively well with that of observed measurements. Our results suggest that "hot spots" of N deposition are, for the most part, spatially distributed according to geographic positions (i.e., relative location from sources and the Great Lakes system) and elevation. We also detect seasonal variations in deposition, showing that total wet atmospheric inorganic N deposition inputs to watersheds (extracted from the four-digit HUC calculations) are highest during the spring (mean = 2.4 kg ha(-1), stddev = 0.29) and lowest during the winter months (mean = 1.4 kg ha(-1), stddev = 0.23). Results also suggest that wet NO3(-) consistently comprises a slightly higher proportion of wet N deposition than wet NH4+ throughout watersheds of New York, ranging from 2.5 to 6.1 kg NO3-N ha(-1) yr(-1) compared to NH4+, which ranges from 2.2 to 4.4 kg NH4-N ha(-1) yr(-1).     

基于冗余分析的成都市府河缓冲带土地利用对水质的影响

土地利用是影响河流水环境质量的重要因素之一。然而,大型城市河流缓冲区的土地利用类型及组成对河流水质的影响方式仍不清晰。选取成都市中心城区的府河及其支流作为研究对象,设置17个水质监测断面,于2018年1月—2019年12月对COD_Mn、NH₄⁺-N和TP 3个水质指标开展连续监测。同时,还获得了相同时段内的降水数据和基于高分卫星(GF-1)影像解译的土地利用数据。在此基础上,利用空间分析以及冗余分析方法,探讨河岸缓冲区内土地利用结构、组成对府河及支流水质的影响。研究结果表明:选取河段从上游到下游的COD_Mn、NH₄⁺-N和TP浓度均呈增加趋势,这3类污染物在上游第一个监测断面浓度依次为1.73、0.26、0.06 mg/L,到下游最后一个监测断面浓度为2.59、0.97、0.15 mg/L。相对于干流,府河支流污染物浓度无明显空间分布特征。从时间上看,6—9月水体中各污染物浓度相对较高。基于冗余分析的结果发现,在河段2 000 m缓冲区范围内的土地利用类型对水质的影响最明显,校正后的解释度达57%,表明河段内污染物质主要源于此区域。该范围内,建设用地与其他生产用地可能是COD_Mn与NH₄⁺-N的主要源区,农业用地是TP的主要来源,生态用地对于COD_Mn与NH₄⁺-N具有一定的吸收分解作用。但是,研究区生态用地以园林绿化用地为主,需要施用磷肥,可能成为水体TP的重要贡献源。因此,合理规划河流2 000 m缓冲范围内的建设用地与生态用地比例,控制园林绿化用地的施肥用量,是保障成都市城市河流水环境安全的重要途径。     

Geochemical characteristics of inorganic sulfur in Shijing River, South China

Different inorganic sulfur species distributed in overlying water, pore water and sediment in a heavily polluted river were determined. The concentrations of S(2-) and SO(4)(2-) in the overlying water were much more than those in the pore water. This result perhaps indicates the S(2-) was mainly from discharged wastewater, not from sediment resuspension. In the sediments, acid-volatile sulfide, chromium(ii)-reducible sulfide, and elemental sulfur were determined by a modified diffusion method. The results indicate that acid-volatile sulfide was the dominant component of the reduced inorganic sulfur, making up about 62% of the total reduced inorganic sulfur.     

Assessment of the exposure of two fish species to metals pollution in the Ogun river catchments, Ketu, Lagos, Nigeria

The concentrations of metals (Ca, Cd, Fe, Mn, Pb and Zn) were determined by flame atomic absorption spectrophotometry in water, sediments and fish samples in the Ogun river catchments, Ketu, Lagos, which is an important bird nesting, fishing and drinking water source. The results show that the southern tip bothering the Lagos lagoon is where the highest metal concentrations are found in the fish species (Tilapia sp. and Chrysichthys sp.), whereas the Agboyi creek segment near the lagoon with higher surrounding human population density recorded higher levels of metals in sediments and water samples. The two fish species accumulated different amounts of metals. However, the differences were not statistically different at p < 0.05. There is a significant correlation (p < 0.05) for Cd concentration in water. The concentrations of Pb in sampling points 3 and 4 as well as Cd, Mn and Fe in all six sampling points exceeds the World Health Organization (WHO) limits for drinking water. Levels of metals obtained for sediments are within the range reported for Nigeria’s river sediments. Based on this study, the human risks for heavy metals in the harvested fish species from the Ogun river catchments, Ketu, are low for now as the concentrations were below the recommended Food and Agriculture Organization (FAO) maximum limits for Pb (0.5 mg/Kg), Cd (0.5 mg/Kg), and Zn (30 mg/Kg) in fish.     

Occurrence and behaviour of 4-nonylphenol in river water of Germany

An analytical method composed of solid-phase-extraction (SPE) followed by gas chromatography-mass spectrometry (GC-MS) has been developed to investigate the occurrence and the behaviour of the endocrine disruptor 4-nonylphenol (4-NP) in river water of Germany. 16 Para-isomers of the complex mixture of 4-NP isomers have been resolved in the SPE-extracts of river water samples. The mass spectra indicate the presence of four distinct groups of isomers. The different groups are characterised by different base peaks of the mass spectra dependent on the substitution of the alpha-carbon on the alkyl chain. The different isomers show (i) alpha-methyl, alpha-ethyl (base peak 149), (ii) alpha-dimethyl (base peak 135), (iii) alpha-methyl, alpha-propyl, alpha-butyl (base peak 121) and (iv) alpha-methyl, alpha-propyl, alpha-butyl (base peak 107) configuration of the alkyl chain. The recovery of the unbranched compound 4-n-NP was > or = 90%. Detection limit and determination limit of the whole analytical procedure were 6 ng L(-1) and 25 ng L(-1), respectively with a relative standard deviation of 11.7%. The concentration of the sum of the 4-NP isomers in all samples of river water ranged from 28 ng L(-1) (Elbe River) to 1220 ng L(-1)(Oder River). In a period of a higher river water level, a higher amount of 4-NP was detected in the Oder River than in a period of a lower water level. Therefore dilution was not the determinant factor of the 4-NP concentration in river water. The diurnal dynamics of the sewage treatment works (STWs) have to be considered as an influencing factor for the presence of 4-NP in river water.     

Multimetric Assessment of Nutrient Enrichment in Impounded Rivers Based on Benthic Macroinvertebrates

In this investigation we evaluated the performance of multiple metrics, based on benthic macroinvertebrates, to assess nutrient enrichment in impounded rivers. Field studies were conducted in the upper reaches of four impounded mountain rivers (Tormes, Riaza, Eresma and Miraflores Rivers) of Central Spain. The watersheds of these rivers are underlain by siliceous rocks. Two sampling sites, upstream and downstream from the reservoir, were established in stony riffles of each impounded river. We used a total of 34 metrics, representing five different metric groups: measures of abundance and richness, percentages of taxonomic groups, percentages of functional feeding groups, measures of dominance and diversity, and biotic indices. Evaluation of different metrics was mainly based on correlation analyses between concentrations of nutrients (NO3-N, NH4-N, PO4-P) and values of individual metrics. Deep releases from the reservoirs were the primary cause responsible for the nutrient enrichment at downstream sampling sites. Chironomidae density, Gastropoda density, % Chironomidae, % Gastropoda, % collector-gatherers and scrapers, proportion of the two most dominant taxa, and Camargo's dominance index exhibited the highest positive correlation coefficients. Conversely, Plecoptera density, Trichoptera density, EPT richness, % Plecoptera, % Trichoptera, % collector-filterers, % predators, % shredders, Simpson's and Camargo's diversity indices, and the average BMWQ score (biotic index) exhibited the highest negative correlation coefficients. Overall it is concluded that the multimetric approach may be a useful technique for the biological assessment of nutrient enrichment in fluvial ecosystems, particularly in upper reaches of siliceous rivers.     

Adsorption of Cotton Fabric Dyestuff Waste Water on Nigeria Agricultural Semi-Activated Carbon

The Kaduna river in Nigeria is in such great environmental stress that the self-purifying capacity of the river has been exceeded as a result of industrial discharges. The river water is blue-green and pollution build-up is evident on the river banks. Techniques were designed to rid the river of visible signs of pollution by incorporating the principles of adsorption and incineration.Semi-activated carbon from agricultural wastes were used to treat the waste water. Residual colors, amber, yellow and orange, were obtained and the solute removed ranged from 96-99.8% and the volatile residue removed by carbon treatment ranged from 3-3.8%. Incineration of 1 kg waste water yielded 40 g solid residue.Adsorption of dyestuff present in the waste water was linear and increased with concentrations of waste water per unit mass of guinea corn carbon. Replicate results yielded: y = 2.5 + 0.130x y = 2.306 + 0.017x where x =log10% concentration of dyestuff waste water (independent variable); y = log10 adsorption of dyestuff waste-weight gramme-1 carbon. Unit of weight = milligramme (dependent variable).For maize carbon, adsorption was linear but decreased with increasing concentrations. Replicate results were: y = 1.583 - 0.21x y = 0.52 - 0.32x x and y here are the same as above; with cane sugar carbon, adsorption was independent of concentrations. Student t-test showed no statistical difference between the replicates at the 99.5% level.