Effect of urban emissions on the horizontal distribution of metal concentration in sediments in the vicinity of Asian large cities

Abstract

Abstract:Metal contents of sediments in Manila Bay -Laguna Lake watershed in the Philippines were measured and detailed horizontal distribution was obtained. The distribution of zinc and lead concentration in Manila Bay clearly shows the effect of anthropogenic contamination and it was explained by the diffusion of lead and zinc rich anthropogenic particles discharged from Pasig River. The sediments in Laguna Lake were mostly natural particulate matters from surrounding mountains and they contained 20 mgPb/kg and 100 mgZn/kg, while the sediment taken at the heavily polluted branches of the Pasig River contained as high as 88 mgPb/kg and 310 mgZn/kg. The lead and zinc concentrations in the sediments of Manila Bay -Laguna Lake watershed were compared with those in the mouth of the Tama River, Tokyo, where the faster deposition of coarser natural origin particles and slower deposition of lead and zinc rich anthropogenic particles determined the sediment concentration. The comparison was also made with Hanoi City, Vietnam. In spite of the difference in time when leaded gasoline was prohibited, the difference in the lead concentrations of roadside deposits and sediments was not obvious in the vicinity of these three target cities. This is probably due to dilution by a large amount of suspended solids conveyed by the Pasig River in the case of the Philippines. Storm water runoff containing roadside deposits and discharge of untreated wastewater were identified as factors increasing zinc and lead concentrations of sediments in receiving waters based on the measurements on roadside deposits and the estimation of the contribution of untreated wastewater.

Heavy metal contamination of coastal lagoon sediments: Fongafale Islet, Funafuti Atoll, Tuvalu

“…The heavy metal concentrations in the coastal sediments of the atoll were much lower than those in the coastal, estuarial, bay, river, lake and agricultural sediments in other environments (except coral reefs) (Hakanson, 1980;Tomlinson et al, 1980;Urase et al, 2006;Amin et al, 2009;Bhuiyan et al, 2010;Varol, 2011). The heavy metal contamination shows considerable variation in both the concentration and presence of different heavy metals.…”

Purification Experiments on the Pasig River, Philippines Using a Circulation-Type Purification System

“…The river is now very polluted due to a human negligence and industrial development [1]. There are many research papers [2][3] focusing on the investigation of the river, however no study has made considerable progress from the point of view of purification. Previously, one author investigated the COD (chemical oxygen demand) at about 15 points along the river [2] and it is interesting to note that the recent COD measurement conducted in the river showed that the value has almost doubled since the year 2000.…”

Heavy Metals in Suspended Sediments in Rivers Flowing Through Megacities in Southeast Asia

“…In Southeast Asia, heavy metals are being accumulated in urban rivers, estuaries, and adjacent coastal zones (Prudente et al, 1994;Urase et al, 2006;Thongra-ar et al, 2008;Zhu et al, 2010) as one of the consequences of the recent rapid urbanization and industrialization. Bioavailability and toxicity of heavy metal depend on its concentration as well as chemical speciation.…”

“…Such high sediment load is largely the result of natural processes (e.g., erosion and transport) in their catchments and often makes water quality control complex in terms of water supply as well as ecological management. Consequently, the deterioration of aquatic ecosystems is closely related to SS in highly turbid rivers because SS serves as the carrier of a number of pollutants including heavy metals, causing secondary and tertiary pollutions in adjacent water bodies (Urase et al, 2006;Zhu et al, 2010), and SS can be also potential food sources for aquatic fauna.…”

“…Thus, it is important to investigate heavy metal property in SS to understand those sources, transport processes, and potential risk in rivers and coastal area. However, such properties of heavy metals in SS have been rarely investigated in Southeast Asia, although the metal accumulations in bottom sediments are often reported in rivers, estuaries, and adjacent coastal zones (Prudente et al, 1994;Urase et al, 2006;Thongra-ar et al, 2008;Zhu et al, 2010).…”