An appraisal of changes in seasonal water quality during passage through a shallow reservoir in Western Poland

Following restoration changes in Antoninek Reservoir physico-chemical and biological processes in the water column and bottom sediments were measured to outline mechanisms of changes in nitrogen, phosphorus and organic matter concentrations during water flow through this reservoir. Intensive mineralisation of organic matter in the shallow sediments stimulated primary production and influenced increasing ammonia and nitrite nitrogen concentrations. Two main factors affected concentrations of phosphorus: (1) its presence in the external loads of river waters entering the reservoir, more important in the colder seasons as the water discharge was higher and (2) from the internal loads coming from bottom sediments. The quality of the river water during its flow through this reservoir improved for most parameters and seasons. However, concentrations of nutrients were still high in waters flowing out from the reservoir and in some months they were higher in the outflow than in waters entering the reservoir.     

An assessment of heavy metal contamination in surface sediment using statistical analysis

The distribution and accumulation of heavy metals in the sediments, especially those nearest of wastewater discharges of south of Spain, were investigated. Sediment samples from 14 locations were collected and characterised for metal content (e.g. Ni, Cu, Zn, Cr, Pb, Mn, Cd and Hg), organic carbon, total nitrogen, total phosphorous, n-hexane-extractable material, carbonates and grain size. Concentration data were processed using correlation analysis and factor analysis. The correlation analysis of concentrations data showed important positive correlations among organic carbon, total phosphorus, Cu, Zn, Cd and Hg, otherwise weak correlations among Mn, Cr, Ni and CO₃ ^2???, indicating that these metals have complicated geochemical behaviours. The use of statistical factor analysis also confirmed these results. Sediments pollution assessment was carried out using geoaccumulation and metal pollution indexes (MPI₈). The results revealed that sediments of Cádiz bay and Sancti Petri channel were uncontaminated with the studied metals.     

Phosphorous speciation in surface sediments of the Cochin estuary

Sequential chemical extraction using chelating agents were used to study the P dynamics and its bioavailability along the surface sediments of the Cochin estuary (southwest coast of India). Sediments were analyzed for major P species (iron bound P, calcium bound P, acid soluble organic P, alkali soluble organic P and residual organic P), Fe, Ca, total carbon, organic carbon, total nitrogen and total sulfur contents. An abrupt increase in the concentration of dissolved inorganic P with increasing salinity was observed in the study region. Iron-bound P exhibited a distinct seasonal pattern with maximum values in the monsoon season when fresh water condition was prevailed in the estuary. As salinity increased, the percentage of iron-bound P decreased, while that of calcium-bound P and total sedimentary sulfur increased. C/P and N/P ratios were low which indicate that large amounts of organic matter enriched with P tend to accumulate in surface sediments. The high organic P contribution in the sedimentary P pool may indicate high organic matter load with incomplete mineralization, as well as comparatively greater percentage of humic substance and resistant organic compounds. Principal component analysis is employed to find the possible processes influencing the speciation of P in the study region and indicate the following processes: (1) the spatial and seasonal variations of calcium bound P and acid soluble organic P was mainly controlled by sediment texture and organic carbon content, (2) sediment redox conditions control the distribution of iron bound P and (3) the terrigenous input of organic P is a significant processes controlling total P content in surface sediments. The bioavailable P was very high in the surface sediments which on an average accounts for 59 % in the pre-monsoon, 65 % in the monsoon and 53 % in the post-monsoon seasons. The surface sediments act as a potential internal source of P in the Cochin estuary.     

Phosphorus speciation in the marine sediment of Kalpakkam coast,southeast coast of India

A study was carried out at Kalpakkam coast to find out the distribution of various fractions of phosphorus (P) in the marine sediment during pre-northeast monsoon period. Samples were collected from ten locations covering ~80 km² of the inner-shelf region. Sedimentary parameters such as sand, silt, clay, and organic carbon percentage were analyzed in order to find out their relation with various P fractions. The sediment was found to be predominantly sandy in nature with low silt and clay content. Among all the fractions (loosely bound (LoP), calcium bound (CaP), iron bound (FeP), aluminum bound (AlP), and organic (OP)), CaP fraction constituted the largest portion (68.7 %) followed by organic fraction (16.3 %). The bioavailable P fractions ranged from 5 to 44 % of the total P (TP) content. Relatively high LoP content was observed at the offshore locations with comparatively high mud percentage as compared with the near-shore locations. As FeP and AlP concentrations were directly proportional to the amount of fine-grain sediment, the low levels of these fractions found in this coastal area were therefore attributed to the sandy nature of the sediments. The order of abundance of the major forms of P in the surface sediments of Kalpakkam coast was as follows: CaP?>?OP?>?LoP?>?AlP?>?FeP.     

Phosphorus geochemistry in a Brazilian semiarid mangrove soil affected by shrimp farm effluents

Wastewater discharge from shrimp farming is one of the main causes of eutrophication in mangrove ecosystems. We investigated the phosphorus (P) geochemistry in mangrove soils affected by shrimp farming effluents by carrying out a seasonal study of two mangrove forests (a control site (CS); a site affected by shrimp farm effluents (SF)). We determined the soil pH, redox potential (Eh), total organic carbon (TOC), total phosphorus (TP), and dissolved P. We also carried out sequential extraction of the P-solid phases. In SF, the effluents affected the soil physicochemical conditions, resulting in lower Eh and higher pH, as well as lower TOC and higher TP than in CS. Organic P forms were dominant in both sites and seasons, although to a lesser extent in SF. The lower TOC in SF was related to the increased microbial activity and organic matter decomposition caused by fertilization. The higher amounts of P oxides in SF suggest that the effluents alter the dominance of iron and sulfate reduction in mangrove soils, generating more reactive Fe that is available for bonding to phosphates. Strong TP losses were recorded in both sites during the dry season, in association with increased amounts of exchangeable and dissolved P. The higher bioavailability of P during the dry season may be attributed to increased mineralization of organic matter and dissolution of Ca-P in response to more oxidizing and acidic conditions. The P loss has significant environmental implications regarding eutrophication and marine productivity.     

Estimation of phosphorus flux in rivers during flooding

Reservoirs in Taiwan are inundated with nutrients that result in algal growth, and thus also reservoir eutrophication. Controlling the phosphorus load has always been the most crucial issue for maintaining reservoir water quality. Numerous agricultural activities, especially the production of tea in riparian areas, are conducted in watersheds in Taiwan. Nutrients from such activities, including phosphorus, are typically flushed into rivers during flooding, when over 90 % of the yearly total amount of phosphorous enters reservoirs. Excessive or enhanced soil erosion from rainstorms can dramatically increase the river sediment load and the amount of particulate phosphorus flushed into rivers. When flow rates are high, particulate phosphorus is the dominant form of phosphorus, but sediment and discharge measurements are difficult during flooding, which makes estimating phosphorus flux in rivers difficult. This study determines total amounts of phosphorus transport by measuring flood discharge and phosphorous levels during flooding. Changes in particulate phosphorus, dissolved phosphorus, and their adsorption behavior during a 24-h period are analyzed owing to the fact that the time for particulate phosphorus adsorption and desorption approaching equilibrium is about 16 h. Erosion of the reservoir watershed was caused by adsorption and desorption of suspended solids in the river, a process which can be summarily described using the Lagmuir isotherm. A method for estimating the phosphorus flux in the Daiyujay Creek during Typhoon Bilis in 2006 is presented in this study. Both sediment and phosphorus are affected by the drastic discharge during flooding. Water quality data were collected during two flood events, flood in June 9, 2006 and Typhoon Bilis, to show the concentrations of suspended solids and total phosphorus during floods are much higher than normal stages. Therefore, the drastic changes of total phosphorus, particulate phosphorus, and dissolved phosphorus in rivers during flooding should be monitored to evaluate the loading of phosphorus more precisely. The results show that monitoring and controlling phosphorus transport during flooding can help prevent the eutrophication of a reservoir.     

万峰湖总有机碳空间分布特征

于2012年9月对万峰湖(水库)的总有机碳(TOC)空间分布特征进行研究,结果显示:TOC含量范围为0.41~3.94 mg/L。TOC在纵向分布上的差异不显著,在垂向分布上,总体呈现出上层中层下层的趋势。TOC在垂向上的分布差异主要源于万峰湖属于深水水库,不同深度水层因光照和温度差异所导致生物量的多寡是致使万峰湖出现上层TOC浓度明显高于中层和下层的主要因素。     

Elemental composition of sediments in Lake Jinzai, Japan: Assessment of sources and pollution

Bottom sediments from Lake Jinzai in southwest Japan were analyzed to determine their chemical compositions and to assess the potential for ecological harm by comparison with sediment quality guidelines. The pollution status of lake sediments was evaluated by employing contamination factor (CF), pollution load index (PLI), and geoaccumulation index (I(geo)), focusing on a suite of elements in lakebed and core sediments. Elevated concentrations of As, Pb, Zn, Cu, TOC, N, and P were present in several layers of the upper core and other surface sediments. The elevated metal concentrations are likely related to the fine-grained nature of the sediments, reducing bottom conditions produced by abundant organic matter, and possibly minor non-point anthropogenic sources. Moreover, correlations between the concentrations of trace metals and organic carbon, nitrogen, phosphorus, and iron, suggest that these elements play a role in controlling abundances. Calculated CF, PLI, and I(geo) indicate that the sediments are strongly polluted with respect to As, moderately to strongly polluted with Zn, and moderately polluted with Pb and Cu. Metal concentrations exceed the New York State Department of Environmental Conservation (NYSDEC) lowest effect level and the Canadian Council of Ministers of the Environment (CCME) interim sediment quality guidelines that indicate moderate impact on aquatic organisms in the study area.     

Monitoring the sedimentary carbon in an artificially disturbed deep-sea sedimentary environment

An area of 0.6 km(2) in the manganese nodule field of the Central Indian Basin was physically disturbed and sediments discharged in the near bottom waters to simulate seabed mining and study its impact on benthic ecosystem. An estimated 2 to 3 tonnes of sedimentary organic carbon (C(org)) was resuspended into the water column during a 9-day experiment. The majority of the sediment cores from within the disturbed area and areas towards the south showed a ~30% increase in C(org) content as well as an increase in carbon burial rates after disturbance, though with a reduction in carbon/phosphorus ratios. High specific surface area (SSA~25 m(2) g(-1)) and low C(org)/SSA ratios (mostly <0.5) are typical of deep-sea sediments. The increased C(org) values were probably due to the organic matter from dead biota and the migration and redeposition of fine-grained, organic-rich particles. Spatial distribution patterns of C(org) contents of cores taken before and after disturbance were used to infer the direction of plume migration and re-sedimentation. A positive relationship was observed between total and labile C(org) and macrobenthos density and total bacterial numbers prior to disturbance, whereas a negative relationship was seen after disturbance owing to drastic reduction in the density of macrofauna and bacteria. Overall decrease in labile organic matter, benthic biota and redistribution of organic matter suggest that the commercial mining of manganese nodules may have a significant immediate negative effect on the benthic ecosystem inducing changes in benthic community structure.     

南通市区河流底泥营养物质污染特征及环境风险分析

以南通市区的学田河、南川河、法伦寺河、城山河及西山河为研究对象,测定了河流表层底泥中的有机质、总氮、氨氮、硝氮、总磷、无机磷及活性有机磷等营养物质指标,分析了污染最重的监测点的污染原因。此外,采用有机指数法、营养物质比值法进行了环境风险评价。得出各条河流底泥均为肥污染级,尤其污染最重的是西山河;各研究河流底泥的碳氮比都很高,说明其营养物质主要来源于周围环境;学田河和西山河底泥的氮磷比较高,说明它们的富营养化程度相对较高。通过回归分析,得出学田河、南川河、法伦寺河及城山河底泥中有机质与总氮及南川河有机质与总磷之间具有良好的线性相关性。     

Sediments as a potential tool for assessment of sewage pollution in Barigüi River, Brazil

Sediments constitute a pollutant trap and have proven to be an efficient tool to identify environmental impacts. Sediments are considered a very important means to assess the level of contamination of water bodies because of their ability to accumulate metals and organic. The anthropogenic inputs of sewage, with or without prior treatment, in aquatic environments, affect the geochemical composition of sediment. In addition, the sediment adsorbs hydrophobic compounds found in feces, such as the fecal sterols. The granulometric and geochemical composition of the sediment of Barigüi River-Brazil was investigated. The results show that silt and clay dominate the granulometric composition of the sediments. The geochemical composition of sediments showed high concentrations of phosphorus and nitrogen. The Redfield ratios confirm the inputs of phosphorus and nitrogen. The TOC/N ratio was used to identify the source of pollution. N/TP ratios were found between 1.0 and 3.5. Clearly, an input of phosphorus, sewage is the most acceptable source, following the historic profile of the Barigüi River. High concentration of nitrogen phosphorus labels the area to be polluted by sewage. To confirm the sewage pollution, adsorbed fecal sterols in sediments were investigated. The concentration of total sterols was found between 0.86 and 304.58 μg g^???1. Two distinguished scenario was found, one severely polluted and another slightly polluted. The highest concentrations of total fecal sterols were associated with sediment whose geochemical composition showed higher levels of TOC, as well as higher proportions of silt and clay. Also, epicoprostanol, a coprostanol isomer, was used as an indicator of the level of treatment or age of the fecal matter because it is formed during the treatment of wastewater and sludge digestion. If the treatment of sludge takes a long time, epicoprostanol can form from cholesterol, and relative proportions of those compounds may be used as an indicator of the presence of untreated sewage in the sediments. The epicoprostanol was found in the range between 0.02 and 9.71 μg g^???1; concentration of up to 0.015 μg g^???1 represents situations where there is strong contamination by sewage. All sites investigated showed a concentration of epicoprostanol higher than the value adopted as threshold. The lower concentration of epicoprostanol found for all sites is consistent with the high concentration found for coprostanol, and this is typical for untreated sewage.     

地表水泥沙与总磷测定值的相关性分析

为研究总磷与泥沙之间的质量浓度关系,采集了三峡库区7个断面的地表水样品,通过筛分、滤膜过滤等方式,分离了水样中不同粒径的泥沙,得到含不同泥沙质量浓度的水样,并同步分析了水样中泥沙和总磷的质量浓度.结果表明,在丰水期,总磷主要来源于泥沙中吸附的有机磷和无机磷,而溶解态磷较少.泥沙与总磷质量浓度可以用线性关系和对数关系模拟,泥沙是影响地表水中总磷测定结果的主要原因之一.     

Trace metals biogeochemistry of Kumaun Himalayan Lakes,Uttarakhand, India

The increasing urbanization, along with tourism, has posed a major threat to the Kumaun Himalayan Lakes, Uttarakhand, India. The total metal concentration in the water, interstitial water, and sediments along with the metal fractionation studies were carried out to understand the remobilization of the trace metals from the sediments of the lakes. The high concentration of the metals in the water column of the lakes generally decreases with depth and the metals release from the sediment is mainly due to the prevalence of anoxic condition at the sediment–water interface and sediment column. The sediment shows that metals Fe and Cr are derived from detrital source, whereas Co, Ni, and Zn are derived mainly from the organic matter dissolution. The sparse correlation of the trace metals with Ti shows most of the metals have chiefly re-precipitated from the water column. The metals speciation studies also supports that metals experience a high rate of anoxic dissolution and their precipitation onto the sediments are determined by the sediment composition and organic matter content. The high concentration of manganese in the interstitial water in the lakes indicates dissolution of organic matter. The released manganese is adsorbed/precipitated as carbonate phase (Nainital Lake) and oxide pahse (in other lakes). The study shows that the trace metals are regenerated from the sediments due to oxyhydroxide dissolution and organic matter decomposition.     

Spatio-temporal variation in physicochemical properties of coastal waters off Kalpakkam, southeast coast of India, during summer, pre-monsoon and post-monsoon period

Seasonal observations on water-quality parameters and chlorophyll-a in the coastal waters off Kalpakkam, southeast coast of India, was carried out covering an area of about 30 km(2) to find out the variations in physicochemical properties during a monsoonal cycle of the year. Most of the parameters exhibited a significant spatial and seasonal variation. It revealed that the coastal water was significantly influenced by freshwater input from the nearby backwaters during North-east monsoon and post-monsoon periods. A marginal increase in pH from coast towards offshore was noticed during the observation. Relatively low salinity values were observed during pre and post monsoon when compared to summer. Bottom water was found to be highly turbid during summer and pre-monsoon conditions when compared to surface. This could be attributed to the strong northerly wind and northward current prior to the onset of southwest monsoon. N, P and Si based nutrients are relatively high in their concentration in the bottom water. Nitrate was significantly high during post-monsoon and contributed greatly towards total nitrogen as evident from the statistical correlation. Ammonia concentration was relatively high in the bottom samples during all the seasons except on a few occasions during post-monsoon. In general, phosphate and total phosphorous values remained low and particularly so in the surface water. Higher silicate concentration was observed in the bottom water, and there was a reducing trend towards offshore. High chlorophyll-a values were observed during summer and surface water was found to have higher pigment concentrations as compared to the bottom. Results show that phosphate acts as the limiting factor for phytoplankton production particularly during post-monsoon period whereas; none of the nutrients were found to be limiting the phytoplankton growth during other seasons.     

玄武湖沉积物中磷的形态分布特征

利用分级提取法分析了玄武湖的沉积磷形态,在玄武湖沉积物中,铝结合态磷的含量较低,平均值为64 mg/kg,其余形态磷中,铁结合态磷为241 mg/kg,有机磷为335 mg/kg,钙结合态磷为394 mg/kg.在环境变化的条件下,铁结合态磷可以释放到间隙水和上层水体中,是湖泊产生富营养化的重要因素;铝结合态磷由于含量少,对湖泊富营养化影响很小;钙结合态磷相对稳定且很难被生物利用,对湖泊富营养化影响不大;有机磷对水体有机负荷影响较大,并影响水体富营养化程度.     

Multivariate analysis for spatial distribution of dissolved organic matters in a large river-type dam reservoir

In contrast to extensive studies of dissolved organic matters (DOM) in natural lakes, the distributions and the characteristics of DOM in artificial dam reservoirs have not been well documented despite a growing demand for the construction worldwide. For this study, spatial variations in the concentrations and the characteristics of DOM in Lake Paldang, a large river-type dam reservoir, were investigated using the concentrations, the specific UV absorbance (SUVA), the synchronous fluorescence spectra and the molecular weight (MW(w)) values. In addition, environmental factors determining the DOM spatial distribution were examined based on a principal component analysis (PCA). Variations in the DOM characteristics were greater than those for the concentrations (1.1-2.4 mg C/L). In contrast to typical lakes, vertical variations with a depth were much smaller than those observed among horizontal sampling sites within the reservoir. Irrespective of the depth, four individual sampling locations were easily distinguished by comparison of some selected DOM characteristics. The protein-like fluorescence (PLF), MW(w) and SUVA values observed at the location near the dam exceeded the corresponding values for the sampling locations near major influent rivers, suggesting that, even for the river-type dam reservoir, the downstream DOM characteristics may be governed by in-lake DOM production processes such as the release from sediments and algal activities. The results of principal component analysis (PCA) revealed that approximately 61% of the variance in DOM distribution might be explained by allochthonous/autochthonous carbon sources and predominant presence of either total nitrogen or total phosphorous over the other.     

Recent sedimentary environment of coastal lagoon in southwestern Japan: evidence from major and trace elements

A geochemical study of the bottom sediments of Lake Shinji and the River Ohashi in southwestern Japan was carried out to determine their elemental compositions and to evaluate the pollution status of lake sediments by employing enrichment factor (EF), pollution load index (PLI), and geoaccumulation index (I _geo). Present-day water quality was also assessed. Results showed that the water quality of Lake Shinji contrasts slightly between the upper and lower parts. The chemical composition of the sediments, as measured by X-ray fluorescence, included major and trace elements and total sulfur (TS). Average abundances of As, Pb, Zn, Cu, Ni, and Cr in the Shinji sediments were 10, 29, 143, 27, 19, and 54 ppm, respectively, compared to 6, 18, 57, 16, 10, and 37 ppm in the river sediments. Based on the EF, PLI, and I _geo, the lake sediments are moderately to strongly polluted with respect to As, moderately polluted with Pb, Zn, and Cr, and unpolluted with Cu and Ni. The high EF and I _geo for As, Pb, and Zn in the lake sediments indicate that metal concentration has occurred in Shinji. Increases in the abundances of these metals are likely related to the fine-grained nature of the sediments, reducing conditions of the bottom sediments, enrichment in organic matter, and possibly a minor contribution from non-point anthropogenic sources. Trace metal contents are strongly correlated with Fe₂O₃ and TS, suggesting that Fe oxides and sulfides play a role in controlling abundances in the investigated areas.     

Fractionation and bioavailability of phosphorus in a tropical estuary, Southwest India

Phosphorus fractionation was employed to find the bioavailability of phosphorus and its seasonal variations in the Panangad region of Cochin estuary, the largest estuarine system in the southwest coast of India. Sequential extraction of the surficial sediments using chelating agents was taken as a tool for this. Phosphate in the water column showed seasonal variations, with high values during the monsoon months, suggesting external runoff. Sediment texture was found to be the main factor influencing the spatial distribution of the geochemical parameters in the study region. Similarly, total phosphorus also showed granulometric dependence and it ranged between 319.54 and 2,938.83 ??g/g. Calcium-bound fraction was the main phosphorus pool in the estuary. Significant spatial variations were observed for all bioavailable fractions; iron-bound inorganic phosphorus (5.04?C474.24 ??g/g), calcium-bound inorganic phosphorus (11.16?C826.09 ??g/g), and acid-soluble organic phosphorus (22.22?C365.86 ??g/g). Among the non-bioavailable phosphorus, alkali-soluble organic fraction was the major one (51.92?C1,002.45 ??g/g). Residual organic phosphorus was comparatively smaller fraction (3.25?C14.64% of total). The sandy and muddy stations showed distinct fractional composition and the speciation study could endorse the overall geochemical character. There could be buffering of phosphorus, suggested by the increase in the percentage of bioavailable fractions during the lean pre-monsoon period, counteracting the decreases in the external loads. Principal component analysis was employed to find the possible processes influencing the speciation of phosphorus in the study region.     

Experimental photochemical release of organically bound aluminum and iron in three streams in Maine, USA

In the present study, the BCR (Community Bureau of Reference) sequential procedure has been applied to determine the zinc partition in sediments taken from a river situated in the Southwest of Romania, in a region subject of intense mining activities. The sampling was performed during three sampling expeditions, organized in the spring, summer, and autumn, 2007. The zinc concentration in different fractions was normalized, its concentration being related to the concentrations of some metals (such as Al or Fe) that are naturally present in sediments. The zinc-contaminated sediments from the investigated area have been evaluated by means of combining the analysis data from the BCR sequential extraction with the normalization to the Al content. The most important zinc collector in the samples taken during the three sampling expeditions is the easily soluble fraction, next being amorphous iron and manganese hydrated oxides fraction, followed by organic matter fraction.     

Implication of two in-stream processes in the fate of nutrients discharged by sewage system into a temporary river

The aim of this study was to better understand the fate of nutrients discharged by sewage treatment plants into an intermittent Mediterranean river, during a low-flow period. Many pollutants stored in the riverbed during the low-flow period can be transferred to the downstream environments during flood events. The study focused on two processes that affect the fate and the transport of nutrients, a physical process (retention in the riverbed sediments) and a biological process (denitrification). A spatial campaign was carried out during a low-flow period to characterize the nutrient contents of both water and sediments in the Vène River. The results showed high nutrient concentrations in the water column downstream of the treated wastewater disposal (up to 13,315 μg N/L for ammonium and 2,901 μg P/L for total phosphorus). Nutrient concentrations decreased rapidly downstream of the disposal whereas nutrient contents in the sediments increased (up to 1,898 and 784 μg/g for total phosphorus and Kjeldahl nitrogen, respectively). According to an in situ experiment using sediment boxes placed in the riverbed for 85 days, we estimated that the proportion of nutrients trapped in the sediments represents 25% (respectively 10%) of phosphorus (respectively nitrogen) loads lost from the water column. In parallel, laboratory tests indicated that denitrification occurred in the Vène River, and we estimated that denitrification likely coupled to nitrification processes during the 85 days of the experiment was significantly involved in the removal of nitrogen loads (up to 38%) from the water column and was greater than accumulation processes.