Data on dissolved metals in Terengganu waters of South China Sea during pre-, post-, and Northeast Monsoon season

Metals are natural elements existed in the environment. However, due to the rapid development of urbanisation and economic, high content of anthropogenic metals are being perceived in polluting the environment. The oceans are known to be a part of the sinking basin for anthropogenic metals ends. Dataset provided is purposely to give an overview of dissolved metals spatial distribution in the South China Sea off the east Peninsular of Malaysia during the pre-, post- and Northeast (NE) Monsoon period. Seawater samples were collected in a grid of 18 stations at 3 different water depth. Dissolved metals were pre-concentrated on-board ship using Chelex-100 resin and analysed using Inductively Coupled Plasma Mass Spectrophotometry (ICPMS). The dataset shows the effect of NE Monsoon on dissolved metals spatial distribution mainly at the area closer to the land. Therefore, this dataset could reveal the past information on anthropogenic metals intrusion in the South China Sea, since Terengganu state was recently pointed to be one of the Malaysian waterfront city. Additionally, this dataset also could help in studying the cycle of metals in the southern South China Sea waters.


a b s t r a c t
Metals are natural elements existed in the environment. However, due to the rapid development of urbanisation and economic, high content of anthropogenic metals are being perceived in polluting the environment. The oceans are known to be a part of the sinking basin for anthropogenic metals ends. Dataset provided is purposely to give an overview of dissolved metals spatial distribution in the South China Sea off the east Peninsular of Malaysia during the pre-, post-and Northeast (NE) Monsoon period. Seawater samples were collected in a grid of 18 stations at 3 different water depth. Dissolved metals were pre-concentrated on-board ship using Chelex-100 resin and analysed using Inductively Coupled Plasma Mass Spectrophotometry (ICPMS). The dataset shows the effect of NE Monsoon on dissolved metals spatial distribution mainly at the area closer to the land. Therefore, this dataset could reveal the past information on anthropogenic metals intrusion in the South China Sea, since Terengganu state was recently pointed to be one of the Malaysian waterfront city. Additionally, this dataset also could help in studying the cycle of metals in the southern South China Sea waters. © 2019 The Author(s). Published by Elsevier Inc. This is an open access article under the CC BY license (http://creativecommons. org/licenses/by/4.0/).

Data
Terengganu coast is located at the east region of Peninsular Malaysia with most of the main rivers flushed out toward the South China Sea. Seawater samples were collected at 18 stations off the south Terengganu coast. Coordinates of the sampling locations are shown in Table 1 below.
In order to assess the effect of Northeast Monsoon towards the distribution of dissolved metals in the South China Sea, sampling was carried out during May 2007 (represent the post-monsoon period), September 2007 (represent the pre-monsoon period) as well as November 2007 (represent the Northeast Monsoon period). Seawater samples were collected in a grid of 18 stations at three (3) different water layers namely surface water (1 m from the sea surface), middle layer (10 m from the sea Specifications Table   Subject Oceanography, analytical chemistry Specific subject area Dissolved metals and Northeast monsoon effects Type of data

Value of the Data
The researcher can use these data as a baseline data for further investigation of the dissolved metals distribution in the East Coast of Peninsular Malaysia waters. The present data could be served as a useful information on tracing the sources of natural or anthropogenic metals which are being flushed out into the Terengganu coast waters. Data on dissolved metals in the Terengganu coastal may provide a better picture on the effect of Northeast monsoon on the distribution and movement of metals in the South China Sea water column. Researchers and Terengganu's stakeholders may use these data for a general overview for further investigation on metals in South China Sea waters in order to monitor the intrusion of anthropogenic metals from land development towards developing Terengganu as a renowned waterfront city. The present data could complete the environmental data gaps on metal cycle in the South China Sea since most past data on metals were focusing on sediment and organisms of the South China Sea surface) and bottom layer (1 m above the sea-bed surface). The concentration of dissolved metals determined during the sampling period was recorded in Tables 2e4 below. Generally, the recorded data shows that influence of Northeast Monsoon on the distribution of dissolved metals in the South China Sea due to high concentration of metals were observed at stations closer to the land. A similar finding was found by Refs.
[1e6] as high load of metals was flushed out from the land-based during heavily rain period.

Experimental design, materials, and methods
Sampling was carried out during May 2007, September 2007 and November 2007 represent post-, pre-and Northeast Monsoon season. Seawater samples were collected at surface (1 m), 10 m and bottom waters in a grid of 18 stations. The sampling area covered approximately 3289 km 2 with the nearest and furthest station was located approximately 0.9 km and 61 km from the Terengganu coastline respectively. Seawater samples were collected using Mercos water sampler and preconcentrated at once, on-board ship under Class-100 portable laminar flow bench. All plastic-wares were previously clean using DECON and soak in 10% of nitric acid in order to remove the impurities. Dissolved metals were pre-concentrated using Chelex-100 resin (sodium form, mesh size of 100e200, powder form, Bio-Rad Laboratories), packed in acid-washed PTFE tubes, washed using ammonium acetate in order to remove saline matrix [6,7] and were eluted using 2 M nitric acid, adopted from William [8] and Bowles et al. [9]. Next, the pre-concentrated dissolved metals were collected into acidwashed centrifuge tubes and kept under 4 C prior transportation to the laboratory. The concentration of dissolved metals was then analysed using Inductively Coupled Plasma Mass Spectrophotometry, Perkin ELMER ELAN 9000. The analytical procedures were validated against CASS-4 (Nearshore Seawater Reference Material for Trace Metals from National Research Council of Canada). Metal recovery results together with the detection limits are recorded in Table 5 below. Blanks were measured to check any metals contamination. The concentration of dissolved metals in per litre basis was calculated Equation (1) below:    Remarks: X: Raw data reading by ICP-MS (mg/L) Pre À concentration factor ¼ Volume of sample passed through the Chelex À 100 column Final volume of pre À concentrated sample