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Plants need cobalt (Co) for nitrogen fixation and encourage seedling growth. If the amount is excessive, cobalt causes a reduction in crop yield and poisoning. This study aims was to monitor the toxicity levels of cobalt in paddy fields. The study was conducted in the lowland rice fields of Karawang and Bekasi regencies by taking 394 samples of topsoil. The soil samples were collected by survey method. The analysis showed that all samples contained total cobalt, ranging from 0.477 to 31.829 ppm. The data is classified into 3 classes, namely: normal, normal-toxic and toxic under the quality standards of heavy metals in the soil [7]. The classification results showed that 391 samples are categorized as the normal class, 3 samples as the normal-toxic class, and there was no sample categorized as toxic class. The results of this study can be use as a reference for stakeholders to conduct land management to avoid cobalt poisoning.

Excessive use of fertilizers and pesticides causes the accumulation of heavy metals in intensive agricultural land. Besides, the development of industries around the agricultural area further aggravates the accumulation of heavy metals. This study aimed to assess spatial distribution of heavy metal contamination in agricultural land in Bandung District. In this study, seven concentrations of heavy metals (Cr, Pb, Cd, Co, Cu, Ni, and Zn) in soils were analysed from 273 sampling sites in paddy and horticultural lands in Bandung Regency, Indonesia. The single pollution index (PI) and the Nemerow Integrated Pollution Index (NIPI) were calculated for each surface sample (0-20 cm) to assess the level of heavy metal pollution. Ordinary Krigging (OK) method was used to delineate the spatial distribution of heavy metals. The results show that the average values of all PIs and NIPI values are at a safe level, except for cobalt which showing slightly polluted. The analysis showed that around 3.23 and 8.76% of soil samples were slightly contaminated with cadmium and cobalt, respectively. The finding can be used as a reference for stakeholders to manage paddy fields against heavy metal contamination.

This research measures the lead, cadmium, copper, nickel, chromium, and arsenic in the paddy fields in Nganjuk Regency. Moreover, this research identifies the effect of these metals to the environment and their location. 105 topsoil samples were collected. The AAS was utilized to ascertain the elemental composition of the soil samples. Numerous soil pollution and ecological risk indices, such as Igeo, PI, IPI, PLI, and PERI, were used to analyze the situation. Spline interpolation with ArcGIS 10.2 was used to study metal distribution. The metal content (mg/kg) in Pb, Cd, Co, Ni, Cr, and As was 10.01, 0.77, 9.60, 5.46, 3.61, and 2.79, respectively. These pollutants had pollution index values of between 0.59 and 2.56 and 0.05 and 0.56 on the lower end of the scale. With an average of 1.10−6, the pollutant load index suggests that all samples are safe. The paddy fields in the research region have an average PERI score of 91.48, indicating a low ecological risk. Most metals researched under agriculturally safe levels will be highly valuable for establishing control and remediation measures in paddy fields.

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