Sediment metals content in upstream Citarum river, West Java Province, Indonesia

Study of metal content in sediments is important for monitoring condition of Citarum river. This study aims to determine several metal namely Fe, Cu, Mn, Zn, Ni, Cr, Cd, Pb, Hg, and As in upstream Citarum river sediments. Research was conducted in the Cirasea sub-watershed, namely Gunung Wayang, Babakan Village, Cikitu Village, Wangi Sagara, Puncak Cae, Koyod, Andir, and Nanjung. Sediment samples were taken once a month from September to November 2022. Several physico-chemical parameter were carried insitu and laboratory. Sediment metal analysis was carried out using the ICP-OES (Inductively Coupled Plasma - Optical Emission Spectrometry) technique. Metal concentrations were compared with standards and the relationship between metal parameters and physico-chemical parameters was analyzed by PCA (Principal Component Analysis). Metals that were not found in all stations were Hg and Cd. The metal found with the largest concentration was Fe, otherwise metal found with the smallest concentration was As. Based on PCA, there are three groups based on metals and physico-chemical parameters. Advanced metal analysis needs to be carried out in the Citarum river from upstream to downstream to determine water quality of Citarum river.


Introduction
Citarum river is on the longest and largest river in West Java Indonesia.Citarum river has length about 300 km and watersheed area about 6080 km 2 .Citarum river has 36 tributaries with length about 873 km.Water from Citarum are utilized to water resources for drink water, industry, fisheries, also for place for industrial waste [1].The river condition threaten many pressure especially for its water condition.Water condition not only about the condition in water column but its sedimentary.One of pollutant substance in sediment is the metals.
Metals can penetrate natural water and become part of the water and sediment through absorption, precipitation, and ion exchange processes [2].The distribution of metals is controlled by dynamic balance and physical-chemical interactions, which are commonly affected by factors such as pH, concentration, type of its chemical compound, conditions of reduction-oxidation reactions, and metal valency [3] .Metals can be toxic and harmful to biota when their content exceeds the standard.Although the presence of heavy metals in water is a natural occurrence that is limited to certain amounts in the water column, sediment, and biota fat, the amount of these heavy metals can increase due to the input of waste from industry and other activities [2].
Study of metal content in sediments is still important for monitoring the condition of Citarum river.There have been many research done to metals concentration in Citarum river.As reported by [4], concentration of REE (Rare earth Elements) in sediment were still meet the recommended value by USGS.Thirteen heavy metals detected in river water and 25 heavy metals were detected in sediment.Earlier than that riset reported that several site in Citarum river have high ecological risk based on its metals concentration in sediment Citarum river [5].
Because of its long and large area, since there are several sub watersheed in Citarum river, there is still lack to cover metals research for all area of Citarum, This research was conducted at Cirasea subwatershed in Citarum river.This study aims to determine the content of several important metals namely Fe, Cu, Mn, Zn, Ni, Cr, Cd, Pb, Hg, and As in upstream Citarum river sediments.

Sampling and analysis of water and sediment
Water sample was taken from surface water in every station.Sediment were surface sediment.Sediment were take from several point from river bank in every station, than composite it as one sampel from each sampling station.To determine the physical and chemical parameters of the water in Citarum River, several physical and chemical parameters were determined in situ using calibrated Water Quality Checker (WQC), Turbidimeter, pH meter, and current meter.Specification of WQC is WQC YSI U 20 to measure water temperature, Dissolved Oxygen (DO), Total Dissolved Solids (TDS), conductivity, and salinity.Specification of pH meter is pH meter from Horiba to measure water pH.Specification of Turbiditimeter is Turbidimeter from Hanchen Turbidity Meter Nephelometer SGZ -200 BS to measure turbidity (NTU).Specification of Current Meter is Current Meter from Geopacks Advance streams flow meter to measure water velocity.Other parameters, such as Chemical Oxygen Demand (COD), Total Nitrogen (TN), Total Phosphorous (TP) and metal content in sediment, were analyzed in the laboratory.
Water sample for COD, TN and TP analysis were preserved using H2SO4 until pH 2. Sediment samples for metal content analysis were stored at 4°C.The analysis of COD, TN and TP were conducted in the laboratory following the procedures described in [6].Sediment metal analysis was carried out using the ICP-OES (Inductively Coupled Plasma -Optical Emission Spectrometry) technique described in [7] with modification.Sediment were destructed with HNO3 and H2O2 solution in high temperature at several minutes, than destruction result were diluted in HNO3 solution.Metals Fe, Cu, Mn, Zn, Ni, Cr, Cd, Pb, Hg, and As were analyzed in Citarum river sediment.

Data analysis
To evaluate the quality of the water and sediment in the estuaries of Banten Bay, the results of the analysis were compared to the water quality standard [8] and the guidelines for sediment quality [9].To identify the physical and chemical parameters that affect the content of metals in the water and sediment of the estuaries, Principal Component Analysis (PCA) was used.All data analyses were conducted following the procedures described in [10] and [11].

Water analytical result in upstream Citarum river
Water analytical result can be seen in Table 1.Data in table is value or concentration range of each parameter from three times water sampling.Most of analytical result from water column were fulfill the standard except DO, COD and TP.DO in station 6-8 (Koyod, Andir and Nanjung area) were exceeded the standard.It seems there are anaerobic condition in that stations.Anaerobic condition could come from anthrofogenic waste from human activities surrounded that stations.That condition could make poor water quality that many site in Upstream Citarum River face it.Most of the upstream Citarum watershed is used for agriculture (65%), built-up land (15%), and forests (10%), and the rest is for other uses (10%) [12].The Upper Citarum River shows moderate to severe levels of pollution based on the Pollution Index from 2002 to 2010 [13.The upstream Citarum River showed a quality status of heavily polluted when compared to National Water Quality Standards for Indonesia (class 2) based on the STORET method [14].
Organic material in station 2-8 were high that shown in COD concentration that exceeded the standard (25 mg/L).High concentration of COD made lower DO concentration in Koyod, Andir and Nanjung.TP in station 7 and 8 higher than standard (0.2 mg/L) shown that aquatic area has higher concentration of organic material.Oxygen consumption higher for organic material degradation in aquatic area that made low DO concentration [15].

3.2.
Metals in upstream Citarum river sediment Metals concentration in upstream Citarum river sediment can be seen in Table 2. Data in table is concentration range of each parameter from three times water sampling.Hg and Cd not found in all station.Fe found in high concentration in all stations, range from 31721.75-63068.24ug/g.As found as lowest concentration among measured metals, range from 3.82-9.5ug/g.Cu, Zn, Pb, Cr, dan As concentration in all stations were fullfill the standard, Nickel concentration in all stations were exceeded the standard (21 ug/g).Nickel could from industrial waste.Nickel could form complex substances with hydroxide, carbonate and sulfate in pH<9 and aerobic water condition, in pH> 9 Nickel could form complex substances with hydroxide and carbonate then precipitated.In anaerobic condition, Nickel also not dissolved [15].Metal, which can easily precipitate in sediment.When the flow rate is low, metal can easily deposit in sediment in the form of clay and silt [16].pH value from all stations were <9, thus made all stations in aerobic conditions, so that Nickel in form of complex substances with hydroxide, carbonate and sulfate.

3.3.
PCA result PCA result can be seen in Figure 2.There are three groups based on metals and physico-chemical parameters.Group one is metals Cr, and Zn that were affected by parameter dissolved oxygen, water temperature, conductivity, TDS, salinity, ORP, turbidity and COD.Group two is metals Cu, Fe, Mn and As , that were affected by pH and water current.Group three is metals Ni and Pb affected by TN and TP.High nickel concentration in all stations higher than standard could be affected from TP concentration in all stations.Analytical result of metals in sediment upstream Citarum River needed more advanced analysis such as bioavability and ecological risk to know metal effect to environment [5].Advanced metal analysis needs to be carried out in the Citarum River from upstream to downstream to determine water quality of Citarum River.

Conclusion
Metals that were not found in sediment upstream Citarum were Hg and Cd.The metal found with the largest concentration was Fe with a range of 31721.75-73660.81µg/g.The metal found with the smallest concentration was As with a range of 3.82 -9.25 µg/g.Based on PCA, there are three groups based on metals and physico-chemical parameters.Advanced metal analysis needs to be carried out in the Citarum River from upstream to downstream to determine water quality of Citarum River.

Table 1 .
Water analytical result in upstream Citarum River

Table 2 .
Metals concentration in upstream Citarum river sediment