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The leather tanning industry in Sukaregang, Garut Regency, produces liquid waste containing Chromium and is discharged directly into the Ciwalen River without a waste treatment process. The content of Cr 6+ as metal ions in the waste can also contaminating groundwater. The movement of Cr 6+ will pass through the soil media before entering to the groundwater wells. The capability of the soil to adsorb the contaminant will reduce the impact on groundwater. The purpose of this study was to determine the ability of the soil in adsorbing and inhibiting the movement of Cr 6+ into groundwater. The study was carried out at Sukaregang, Garut Regency and conducting adsorption experiments with a batch system. The analysis was carried out using the Langmuir and Freundlich isotherm model. The experimental results showed that Cr 6+ adsorbed ranged from 38% to 57% of the initial concentration. The results from Langmuir Isotherm were: the distribution coefficient (K ads ) was 0.45 L/mg and the maximum adsorption capacity (q m ) was 2.44 mg/100g sorbent with R 2 = 0.959 and Freundlich Isotherm was: q m was 2,86 mg/100g sorbent and K ads was 0,35 L/mg with R 2 = 0,860. This large adsorption capacity is caused by soil texture and soil organic content. The soil in Sukaregang tanning industries has a high adsorption capacity towards Cr 6+ contaminants. Keywords : adsorption, chromium, Cr 6+ , contaminant, volcanic soil, Garut ABSTRAK Industri penyamakan kulit di wilayah Sukaregang, Kabupaten Garut, menghasilkan limbah cair yang mengandung Kromium dan dibuang ke Sungai Ciwalen tanpa proses pengolahan limbah. Kandungan ion logam Cr 6+ pada limbah dapat mencemari air tanah. Pergerakan ion logam Cr 6+ akan melalui media tanah sebelum memasuki sumur-sumur penduduk. Beberapa jenis tanah mempunyai kemampuan untuk mengadsorpsi ion pencemar sehingga tidak semua limbah yang meresap ke dalam tanah mencemari air tanah. Tujuan dari penelitian ini adalah untuk mengetahui peranan tanah dalam menghambat pergerakan ion logam Cr 6+ ke dalam air tanah. Penelitian dilaksanakan dengan pengambilan sampel tanah di daerah Sukaregang, Garut, dan melakukan percobaan adsorpsi dengan sistem batch. Sementara analisis dilakukan dengan menggunakan model isotherm Langmuir dan Freundlich. Hasil percobaan menunjukkan konsentrasi Cr 6+ yang teradsorpsi berkisar 38 – 57 % dari konsentrasi awal. K ads sebesar 0,45 L/mg dan q m sebesar 2,44 mg/100g tanah dengan nilai R 2 = 0,959 menggunakan isoterm Langmuir dan isoterm Freundlich memberikan nilai q m sebesar 2,86 mg/100 g sorbent dan K ads sebesar 0,35 L/mg dengan R 2 = 0,860. Tingginya daya adsorpsi ini disebabkan oleh tekstur tanah dan kandungan bahan organik. Tanah di wilayah penelitian memiliki daya adsorpsi yang besar terhadap kontaminan Cr 6+ . Kata kunci: adsorpsi, kromium, Cr 6+ , kontaminan, tanah vulkanik, Garut

Groundwater is an extremely valuable resource thus its pollution a call for concern. Amongst the major threats, agricultural leachates often contribute significantly to groundwater pollution. This paper reports an investigation on the effects of citrus agriculture on the groundwater quality aspects of Osakishimojima island. Fifty-one groundwater samples were collected and analyzed for major ions and nutrients. The Gibbs diagram revealed that the overall hydrogeochemical environment of the study area is controlled by rock-water interaction. Two main hydrochemical facies (CaMg-HCO3 and CaMg-SO4) were identified. 48 groundwater samples showed PO43⁻-P content (0.06 - 3.2 mg/L), which exceeds WHO’s recommended maximum permissible limit. High contamination of PO43⁻-P was noticed at depth zones between 3 to 6 m while the highest concentrations were found at depths of 5 m. NO3−-N contamination of groundwater was also observed to decrease with depth. High levels of PO43⁻-P in groundwater may be as a result of heavy fertilizer application by farmers.

This paper evaluates environmental conditions responsible for the high concentrations of trace metals in Indonesian coastal groundwater. Indramayu, which has significant potential groundwater resources, but for which limited information is available regarding its vulnerability, is selected as our study area. Results show that Fe2+ and Mn2+ are natural contaminants in the groundwater of the study site. The correlations of trace metals with salinity and redox-sensitive parameters verify that saline water has a significant impact upon the dissolution of Fe and Mn. Furthermore, reductive condition is confirmed to be responsible for Fe and Mn dissolution with a less significant correlation compared to salinity. Moreover, the high concentrations of trace metals are coupled with high dissolved organic carbon (DOC), which indicates that reductive environment may arise because of organic-matter decomposition. Finally, the impact of human activity upon Fe and Mn dissolution is identified at the northern tip of Indramayu, where trace-metal contents are significantly elevated. Further, in the southern part, the groundwater condition is relatively more natural; thus, the impact of human activity upon the presence of Fe and Mn is lesser in this region.

Geochemical evaluation of the species and potential sources of P in groundwater in and around Mataram City, Lombok Island, Indonesia can aid in the initial research on evaluating the fate of P when detailed geological information is unavailable. The results of ion chromatography and inductively coupled plasma-optical emission spectroscopy show that the concentrations of PO43– and total dissolved P (TDP) in groundwater range from approximately 0.1 to 8.5 mg l–1 and from 0.04 to 2.95 mg l–1, respectively. Dissolved inorganic P accounted for 86%, on average, of the TDP concentration, and PO43– represented the predominant P species in this groundwater. The potential sources for most of this dissolved PO43–, according to indices developed based on the PHREEQC software and groundwater quality data, could be the dissolution of hydroxyapatite and/or vivianite minerals. However, the potential sources of dissolved PO43– in groundwater with a TDP concentration of ≥ 1 mg l–1 is likely to be the reduction of Fe(III)–(hydro)oxides, the initial decomposition of organic matter, or the dissolution of carbonate-rich fluorapatite considering the Fe2+, dissolved organic carbon, Ca2+ and F− concentrations measured. In addition, as several groundwater samples had a TDP concentration of ≤ 1 mg l–1 and comparatively high concentration of NO3–, other potential sources of dissolved PO43– in this groundwater could be anthropogenic.

The origin of ammonium-nitrogen in Indonesian coastal groundwater has not been intensively examined, meanwhile the elevated concentration remains a concern. This research aims at tracing the potential sources of ammonium-nitrogen in the groundwater of Indramayu, Indonesia where groundwater is vital for livelihood. From results, a combined examination of nitrogen isotope, coliform bacteria, land-use, and geology confirmed the natural and anthropogenic origins of ammonium-nitrogen in the groundwater. In the brackish-water aquaculture region, groundwater has &delta, 15NNH4 values from +1.8 to +4.8&permil, signifying that ammonium-nitrogen is derived from mineralization of organic nitrogen to ammonium. Furthermore, ammonium has a significantly positive relationship with sodium indicating the exchangeable ammonium is mobilized to groundwater via cation exchange. Meanwhile ammonium-nitrogen from anthropogenic waste was detected in agricultural and residential region. The groundwater has more varied &delta, 15NNH4 values, from &minus, 2.9 to +16.1&permil, which implies attenuation of ammonium-nitrogen from several sources namely manure, mineral fertilizer, sewage, and pit latrines. Also, the presence of E. coli confirms the indication of human and animal waste contamination. However, since ammonium has no relationship with sodium, cation exchange is not feasible and ammonium-nitrogen flows into the groundwater from anthropogenic sources along with liquid wastes.

Indonesian coastal alluvial plain has a large groundwater storage capacity. However, human perturbation to the groundwater environment has resulted in groundwater contamination. Nitrogen species are parameter those usually detected in Indonesian coastal groundwater. The main objective of this study was to evaluate the possible sources of ammonium (NH4+-N), as one form of nitrogen species, using both chemical properties and geographic information. The study site was Indramayu, a developing rural area located in the northern part of West Java. In August 2017, 20 groundwater and river water samples were collected from sites representative of various types of land-use. The chloride (Cl-) concentration in the samples ranged from 15 mg/L to 12,000 mg/L. Most of the locations represented fresh-brackish to brackish-salt water conditions, indicating the influence of seawater on the groundwater samples. Furthermore, analysis of several nitrogen species identified high NH4+-N concentrations in the samples. Based on the relationship between Cl- and NH4+-N, samples were clustered into three groups. The first and second groups exhibited linear correlations, while in the third group, no relationship between these two parameters was identified. The land-use associated with each group was then evaluated. The main NH4+-N source in the first group was identified as organic sediment, where NH4+-N may be released through ion exchange with sodium, facilitated by the high salinity conditions. The source of NH4+-N in the second group was suggested to be a combination of sediment, fertilizer, and human and animal waste. Finally, it was hypothesized that the source of NH4+ in the third group is mainly human waste.

Airtanah dangkal di Banaran Sukoharjo dan Lawean Kerto Suro, Jawa Tengah, telah tercemar zat organik yang ditandai dengan tingginya kandungan COD. Kandungan COD dalam airtanah berkisar antara 10 mg/L sampai 150 mg/L. Salah satu penyebab tingginya COD adalah pembuangan air limbah dari industri tekstil tanpa pengolahan ke lingkungan yang kemudian bergerak hingga mencapai airtanah. Pengolahan air limbah sebelum dibuang ke lingkungan merupakan cara yang tepat untuk mengatasi masalah pencemaran ini. Metode yang digunakan dalam penelitian ini adalah sistem batch melalui proses koagulasi-flokulasi. Percobaan diawali dengan penambahan kaporit dan kapur untuk menurunkan intensitas warna, kemudian tanah lempung untuk menaikkan kandungan partikel tersuspensi, dan penambahan tawas sebagai koagulan. Penambahan 2 gram kaporit; 0,3 gram kapur; 1 gram lempung; dan 1 gram tawas ke dalam 500 ml air limbah, pada pengadukan 200 rpm selama 2 menit, berhasil menurunkan COD sebesar 79% yakni dari 615 mg/L menjadi 130 mg/L, dan warna sebesar 99% yakni dari 7000 PCU menjadi 45 PCU. Penurunan COD dan warna pada air limbah akan meminimalkan dan mencegah terjadinya pencemaran airtanah, karena kandungan COD 130 mg/L telah memenuhi baku mutu limbah. Warna belum tercantum dalam bakumutu limbah, namun dengan kondisi air limbah yang sudah tidak berwarna maka limbah telah memenuhi syarat dari segi estetika.

Potensi airtanah pada suatu cekungan tidak terlepas dari kondisi hidrogeologi di wilayah itu sendiri. Cekungan airtanah Indramayu, yang berada di pesisir utara Jawa Barat, hingga kini belum diketahui secara pasti potensi cadangannya. Penelitian ini bertujuan untuk mengetahui potensi cadangan air tanah berdasarkan rekonstruksi hidrogeologi data bor. Hasil interpretasi hidrogeologi menunjukkan bahwa litologi akuifer didominasi oleh endapan lempung dengan sisipan lanau, sedikit pasir halus di bagian atas, endapan lempung marin dengan sisipan lanau, dan pasir halus di bagian bawah. Hasil perhitungan menunjukkan prediksi cadangan airtanah yang cukup potensial. Nilai rata – rata potensi airtanah bebas adalah 65.213,8 m 3 /hari atau 0,754 m 3 /det. Nilai rata – rata potensi airtanah tertekan adalah 79.557,1 m 3 /hari atau 0,920 m 3 /det. Tetapi kualitas airtanah di wilayah Losarang – Lobener – Pasekan – Sindang sebagian besar payau dan memiliki nilai DHL yang tinggi, berkisar antara 4710 – 11400 µs/cm. The groundwater potential of a basin depends on the hydrogeology of the area. Indramayu groundwater basin is located at the north coast of Java Island. Its reserves potential was not identified despite its importance. The objective of this research was to understand the potential of groundwater reserves based on hydrogeological reconstruction from drilling data analysis. The results of the hydrogeology interpretation had indicated that the aquifers lithology are dominated by clay deposits with silt layering, slightly fine sand at the top, marine clay deposits with silt inserts, and fine sand at the bottom. The calculation results had indicated a good potential of groundwater reserves. The mean value of the unconfined groundwater is 65,213.8 m 3 /day or 0.754 m 3 /sec. The mean value of the confined groundwater is 79,557.1 m 3 /day or 0.920 m 3 /sec. However, groundwater supply potential is not supported by the quality. The groundwater in Losarang - Lobener – Pasekan-Sindang area is brackish and has a high DHL value (4710 – 11400 µs/cm).

Airtanah bebas merupakan salah satu sumber air bersih bagi penduduk di Kabupaten Bandung bagian selatan. Pemanfaatannya dilakukan dengan cara membuat sumur gali maupun sumur pantek. Lokasi sumur-sumur tersebut berdekatan dengan sumber pencemar domestik dan pertanian sehingga rentan terkontaminasi. Pencemar yang dapat timbul pada air sumur akibat limbah domestik adalah solid, ammonium, dan bakteri coliform. Sementara, pencemar nitrat umumnya bersumber dari kegiatan pertanian. Untuk mengetahui pencemaran airtanah di lokasi penelitian, dilakukan analisis kimia air dan kandungan bakteri coliform, pada 21 conto air dari sumur gali di Kabupaten Bandung bagian selatan. Pemilihan lokasi berdasarkan pada hasil pemantauan kepadatan pemukiman menggunakan citra satelit pada aplikasi Google Earth, kemudian selanjutnya disesuaikan dengan kondisi lapangan di wilayah penelitian. Hasil analisis menunjukkan telah terjadinya pencemaran solid, nitrat, ammonium, dan coliform di beberapa titik. Hasil pemantauan lapangan memperkirakan nitrat berasal dari kegiatan pertanian, sedangkan solid, ammonium, dan coliform berasal dari limbah domestik. Pergerakan pencemar sampai ke airtanah ini didukung oleh pola aliran airtanah di lokasi tersebut. Unconfined groundwater is the source of clean water to residents in the southern part of Bandung Regency. The need of water is fulfilled through shallow drilling of wells and panteks. The locations of the wells are close to domestic and agricultural pollution sources, so they are vulnerable to get contaminated. Pollutants that may arise in wells water due to domestic waste are solid, ammonium, and coliform bacteria. While, nitrate are generally derived from agricultural activities. To determine the contamination of groundwater at the study area, chemical analysis and coliform bacteria were conducted from 21 wells in southern part of Bandung Regency. The dug well locations were chosen based on the results of monitoring the residential density based on satellite images from the Google Earth application and adjusted to the field conditions in area of research. The result of analysis showed that contamination of solid, nitrate, ammonium, and coliform had occurred at some points. Result of field monitoring estimated that nitrate had derived from agricultural activities, while solid, ammonium, and coliform came from domestic waste. The movement of contaminants to groundwater was supported by the groundwaterflow pattern at the location.

Air permukaan dan airtanah dangkal pada sumur-sumur gali di sepanjang ruas-ruas sungai yang melintasi kota Cianjur ke arah hilir telah dianalisis untuk mengetahui tingkat pencemarannya. Air Permukaan dan Airtanah dangkal di Hilir kota Cianjur telah mengalami pencemaran pada tingkat yang berbeda. Pada air permukaan pencemaran ditandai dengan kandungan BOD tinggi sehingga air tidak dapat langsung dimanfaatkan sebagai bahan baku air minum, tetapi masih dapat dimanfaatkan sebagai air irigasi dan perikanan. Proses pemurnian kembali air di daerah studi tampaknya tidak akan terjadi karena jumlah rata-rata limbah yang masuk secara acak lebih besar daripada daya pulih aliran di daerah tersebut. Gejala pencemaran Nitrogen telah tampak pada air tanah dangkal, tetapi air masih dapat digunakan sebagai sumber air minum. Untuk mengantisipasi memburuknya keadaan di masa mendatang, perlu mulai difikirkan untuk mengelola sumberdaya air daerah ini dengan pendekatan hidrologi urban.

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