Effects of sediment geochemical properties on heavy metal bioavailability.

Ecological risk assessment and source identification for heavy metals in surface sediment from the Liaohe River protected area, China

Risk assessment and source analysis of soil heavy metal pollution from lower reaches of Yellow River irrigation in China.

Contamination of heavy metals in sediment is regarded as a major crisis globally, with a large SHARE in developing countries, such as Bangladesh. The objective of this study is to assess the contamination level and seasonal variation of heavy metals and their ecological risk in sediments. Heavy metals (Cr, Ni, Cu, As, Cd, and Pb) in sediments were investigated from eight different sites of Paira River situated at the southern part of Bangladesh and metals were measured by using inductively coupled plasma mass spectrometer. The mean concentration of Cr, Ni, Cu, As, Cd, and Pb in sediments was 45, 34, 30, 12, 0.72 and 25 mg/kg dw, respectively. Metals in sediment during winter were higher than summer season. The concentrations of metals in sediment were compared with both background and toxicological reference values. The comparative results suggested that the selected metals created an adverse effect on the aquatic ecosystems of the studied river. The pollution load index for three sites were higher than baseline values indicating progressive deterioration of sediments by heavy metal. Potential ecological risks of metals in sediment indicated moderate to considerable risk. This study suggested that more attention should be directed to the comprehensive risk assessment of heavy metals of this riverine aquatic environment.

Preliminary assessment of heavy metal contamination in surface sediments from a river in Bangladesh

Mediterranean Sea, Egypt is an economically important marine environment. During the last decades there has been extensive increase in the levels of urbanization and industrialization along its coastal area. Therefore, the present work attempts to determine the status of heavy metals distribution in sediment samples, and their ecological risk assessment in the studied area. Twenty surfacial sediment samples were collected from different selected stations along the Egyptian Mediterranean Sea. The samples were homogenized and placed into sealed polyethylene bags, carried to the laboratory in an ice box and stored at −20 °C in the dark until analysis. The results revealed that Fe had the highest mean value (243–38045 μgg−1) followed by Mn (17–1086 μgg−1), and a lower concentrations were found for Co (0.43–26.39 μgg−1) and Cd (0.04–0.47 μgg−1). Risk assessment showed that Cd had the highest ecological risk (Er = 21.52), followed by Pb (Er = 3.01), while Zn had the lowest risk (Er = 0.23). Both the ecotoxicological index method and the potential ecological risk index (RI) suggested that the combined ecological risk of the studied metals may be low. Multivariate statistical analysis (Cluster and Factor analysis) suggested that the lithogenic factor dominants the distribution of most part of the considered metals in the study area. Multivariate analysis has been proved to be an effective tool for providing suggestive information regarding heavy metal sources and pathways. The results of this study provide valuable information about metal contamination in sediments along the Mediterranean Sea for over than 1200 km.

/pdf/potential-ecological-risk-of-heavy-metals-in-sediments-from-1k9gpl5apj.pdf

Potential ecological risk of heavy metals in sediments from the Mediterranean coast, Egypt

Distribution characteristics and potential ecological risk assessment of heavy metals (Cu, Pb, Zn, Cd) in water and sediments from Lake Dalinouer, China.

Surface sediment and water samples were collected from Daihai Lake to study the biogeochemical characteristics of nitrogen and phosphorus, to estimate the loads of these nutrients, and to assess their effects on water quality. The contents and spatial distributions of total phosphorus (TP), total nitrogen (TN), and different nitrogen forms in sediments were analyzed. The results showed that concentrations of TN and TP in surface sediments ranged from 0.27 to 1.78 g/kg and from 558.31 to 891.29 mg/kg, respectively. Ratios of C : N ranged between 8.2 and 12.1, which indicated that nitrogen accumulated came mainly from terrestrial source. Ratios of N : P in all sampling sites were below 10, which indicated that N was the limiting nutrient for algal growth in this lake. Effects of environment factors on the release of nitrogen and phosphorus in lake sediments were also determined; high pH values could encourage the release of nitrogen and phosphorus. Modified Carlson’s trophic state index () and comprehensive trophic state index () were applied to ascertain the trophic classification of the studied lake, and the values of and ranged from 53.72 to 70.61 and from 47.73 to 53.67, respectively, which indicated that the Daihai Lake was in the stage of hypereutropher.

/pdf/effects-of-environmental-factors-on-nutrients-release-at-2i7wb2664q.pdf

Effects of Environmental Factors on Nutrients Release at Sediment-Water Interface and Assessment of Trophic Status for a Typical Shallow Lake, Northwest China

Concentrations and vertical distributions of total nitrogen (TN), total phosphorus (TP) and their different forms in sediments obtained from nine locations of Lake Dalinouer in September 2008 were analyzed. The results demonstrated that TP in surface sediments ranged from 0.493 to 0.904 g/kg, and inorganic phosphorus was the main fraction of total phosphorus, ranging from 335 to 738 mg/kg. Simultaneously, the autogenetic calcium phosphorus (ACa-P) was the main fraction of inorganic phosphorus, ranging from 145.4 to 543.2 mg/kg. Vertical distribution of different phosphorus forms in different sediment cores was distinguishing, and most of them tended to increase toward the surface sediment, indicated that the phosphorus concentration was related to the humanity with a certain extent. The relationships between TP and occluded phosphorus and ACa-P were significant. Nitrogen in the sediment was composed mainly of organic nitrogen, accounting for grater than 80 % of TN. NO3
 −-N was the dominate fraction of inorganic nitrogen in the surface sediment, ranging between 51 and 346 mg/kg (151.1 ± 104.4 mg/kg), and accounting for between 2.2 and 17.7 % of total sediment nitrogen (6.2 ± 5.6 %). The ratio of organic carbon and TN in sediment was in range of 6.0–25.8 and presented a tendency of lake centre >lake sides, indicating that nitrogen accumulated in the sediments from lake sides came mainly from terrestrial source and nitrogen was mainly autogenetic in lake centre. Ratio of N:P in all sampling sites was below 14, indicated that N was the limiting nutrient for algal growth in this lake.

Spatial variations and distributions of phosphorus and nitrogen in bottom sediments from a typical north-temperate lake, China

Organic carbon (OC) in lake sediments plays an important role in terrestrial ecosystem carbon cycle. The Inner Mongolia Plateau contains a number of shallow and freshwater lakes, with a total lake area of more than 8,000 km2, accounting for an approximate 10 % of the total lake area in China. The Inner Mongolia Plateau lakes act as important OC sink in mid-high latitude regions. In this study, heavy and light fractions of OC and OC species were analyzed in sediments from four typical lakes in the Inner Mongolia Plateau. Meanwhile, to identify OC origins, allochthonous and autochthonous OC were calculated based on a binary model. Furthermore, total organic carbon (TOC) storage, active carbon pool (ACP), and stable carbon pool (SCP) over the past 150 years were estimated in the Inner Mongolia Plateau. The dominating direct findings of the current research are that heavy fraction OC plays a key role as carbon sink in mid-high latitude regions due to its percentage of more than 90 % in TOC. The percentages of allochthonous OC in TOC are high, 86.4, 66.7 and 72.5 %, in Daihai Lake (DH), Dalinuoer Lake (DLNE), and Hulunhu Lake (HLH), respectively, which indicates that allochthonous OC is dominant in DH, DLNE, and HLH. The range of humin is 62.15–84.03 % in these four lakes. The average OC accumulation rate calculated in this work is 1.37 g C m−2 year−1 in these four lakes. Comparatively, OC storages in sediments from lakes in the Inner Mongolia Plateau are relatively more stable than from those lakes located in tropical and sub-tropical regions. An estimate of the TOC burial, SCP and ACP in lake sediments would be 1.64 × 1012, 1.52 × 1012, and 1.20 × 1011 g C, respectively, over the past 150 years in the Inner Mongolia Plateau.

Organic carbon fractions and estimation of organic carbon storage in the lake sediments in Inner Mongolia Plateau, China

The aim of this study is to examine and interpret the spatial distribution of sedimentary humic substances in Lake Dalinouer. Humic substances in sediments were analyzed separately in different fractions: humins (HM), humic acid (HA), fulvic acid (FA), and different forms of organic carbon. The results showed that total organic carbon (TOC) contents varied from 7.25 to 65.54 g kg−1 with a mean of 36.37 ± 17.74 g kg−1. It was found that high TOC concentrations were at lake’s center and low TOC concentrations occurred at the estuary of inflows. Different redox conditions caused by water depth were of the most important factors which might influence TOC contents. Concentrations of HM, HA, and FA in sediments were detected in range of 6.40–58.16 g kg−1, 0.27–3.50 g kg−1, and 0.27–4.26 g kg−1, respectively. Of them, HM was the dominant form and accounted for 74–94% of TOC and 80–90% of humus. Organic Sediment Index (OSI) was used to assess the organics accumulation, and the value of OSI ranged from 0.001 to 0.30, which indicated that Lake Dalinouer was relatively clean. The relative high degree of humidification was found in the eastern of lake, where it should be taken into consideration seriously.

https://downloads.hindawi.com/archive/2014/502597.pdf

Dekun Hou

Papers

Distribution characteristics and potential ecological risk assessment of heavy metals (Cu, Pb, Zn, Cd) in water and sediments from Lake Dalinouer, China.

Effects of Environmental Factors on Nutrients Release at Sediment-Water Interface and Assessment of Trophic Status for a Typical Shallow Lake, Northwest China

Spatial variations and distributions of phosphorus and nitrogen in bottom sediments from a typical north-temperate lake, China

Organic carbon fractions and estimation of organic carbon storage in the lake sediments in Inner Mongolia Plateau, China

Spatial Distributions of Humic Substances and Evaluation of Sediment Organic Index on Lake Dalinouer, China