Microplastic accumulation in riverbed sediment via hyporheic exchange from headwaters to mainstems

Bidirectional flow between surface water and sediment leads to high accumulation of small and lightweight microplastics in rivers.

Response of Variation of Water and Sediment to Landscape Pattern in the Dapoling Watershed

The relationship between water-sediment processes and landscape pattern changes has currently become a research hotspot in low-carbon water and land resource optimization research. The SWAT-VRR model is a distributed hydrological model which better shows the effect of land use landscape change on hydrological processes in the watershed. In this paper, the hydrological models of the Dapoling watershed were built, the runoff and sediment yield from 2006 to 2011 were simulated, and the relationship between landscape patterns and water-sediment yield was analyzed. The results show that the SWAT-VRR model is more accurate and reasonable in describing runoff and sediment yield than the SWAT model. The sub-basins whose soil erosion is relatively light are mostly concentrated in the middle reaches with a slope mainly between 0–5°. The NP, PD, ED, SPIIT, SHEI, and SHDI of the watershed increased slightly, and the COHESION, AI, CONTAG, and LPI showed a certain decrease. The landscape pattern is further fragmented, with the degree of landscape heterogeneity increasing and the connection reducing. The runoff, sediment yield and surface runoff are all extremely significantly negatively correlated with forest, which implies that for more complicated patch shapes of forest which have longer boundaries connecting with the patches of other landscape types, the water and sediment processes are regulated more effectively. Therefore, it can be more productive to carry out research on the optimization of water and soil resources under the constraint of carbon emission based on the SWAT-VRR model.

Quality Indeks dan Konsentrasi Logam Berat dalam Perairan dan Sedimen di Perairan Kota Makassar

Kota Makassar merupakan pusat kota di Provinsi Sulawesi Selatan yang memiliki aktifitas wilayah pesisir, seperti pemanfataan industri, pariwisata, transportasi laut serta memiliki dua sungai besar yang muara di perairan. Penelitian ini bertujuan untuk mengetahui konsentrasilogam berat dalam air dan sedimen serta menentukan status mutunya. Pengamatan dilakukan pada 10 lokasi strategis sumber pencemar seperti pabrik, hotel, muara sungai serta pelabuhan dengan mengambil sampel air dan sedimen dan selanjutnya dianalisis di laboratorium untuk logam berat Cd, Cr, Hg, Zn, Cu dan Pb. Statistik deskriptif digunakan untuk menganalisis data yang ada. Metode Indeks Pencemar dan Storet (Storage and Retrieval) digunakan untuk menentukan status mutu air dan sedimen dari logam berat untuk biota laut. Hasil penelitian ini menunjukkan perairan Kota Makassar tergolong dalam kategori “Cemar Ringan” berdasarkan hasil perhitungan indeks Pencemar sedangkan status mutu perairan tergolong “Cemar Berat”. Parameter logam berat di kolom perairan yang melampaui baku mutu adalah Krom (0,016±0,005) dan Tembaga (0,112±0,035). Sedangkan untuk parameter logam berat sedimen secara keseluruhan masih berada dalam ambang batas baku mutu yang telah ditentukan. Kondisi tercemar berasal dari aktifitas reklamasi pantai serta sumber alami dan limbah domestik dari aktifitas masyarakat cukup tinggi.ABSTRACTMakassar City is the city center in South Sulawesi Province which has coastal area activities, such as the use of industry, tourism, sea transportation and has two large rivers that estuary into the waters. This study aims to determine the concentration of heavy metals in water and sediment and determine their quality status. Observations were made at 10 strategic locations of pollutant sources such as factories, hotels, river mouths, and ports by taking water and sediment samples and then analyzed in the laboratory for heavy metals Cd, Cr, Hg, Zn, Cu, and Pb. Descriptive statistics are used to analyze the existing data. The Pollutant Index and Storet (Storage and Retrieval) method is used to determine the status of water and sediment quality of heavy metals for marine biota. The results of this study indicate that the waters of Makassar City are classified as "Lightly Polluted" based on the results of the calculation of the Pollutant index while the status of the water quality is classified as "Heavy Polluted". Parameters of heavy metals in the water column that exceed the quality standard are chromium (0,016±0,005) and copper (0,112±0,035). Meanwhile, the parameters of the sediment heavy metals as a whole are still within the specified quality standard. Polluted conditions derived from coastal reclamation activities as well as natural sources and domestic waste from community activities are quite high.

Seasonal variations and co-occurrence networks of bacterial communities in the water and sediment of artificial habitat in Laoshan Bay, China

Marine bacteria in the seawater and seafloor are essential parts of Earth’s biodiversity, as they are critical participants of the global energy flow and the material cycles. However, their spatial-temporal variations and potential interactions among varied biotopes in artificial habitat are poorly understood. In this study, we profiled the variations of bacterial communities among seasons and areas in the water and sediment of artificial reefs using 16S rRNA gene sequencing, and analyzed the potential interaction patterns among microorganisms. Distinct bacterial community structures in the two biotopes were exhibited. The Shannon diversity and the richness of phyla in the sediment were higher, while the differences among the four seasons were more evident in the water samples. The seasonal variations of bacterial communities in the water were more distinct, while significant variations among four areas were only observed in the sediment. Correlation analysis revealed that nitrite and mud content were the most important factors influencing the abundant OTUs in the water and sediment, respectively. Potential interactions and keystone species were identified based on the three co-occurrence networks. Results showed that the correlations among bacterial communities in the sediment were lower than in the water. Besides, the abundance of the top five abundant species and five keystone species had different changing patterns among four seasons and four areas. These results enriched our understanding of the microbial structures, dynamics, and interactions of microbial communities in artificial habitats, which could provide new insights into planning, constructing and managing these special habitats in the future.