Tracking the sources of allochthonous organic matter along a subtropical fluvial-estuarine gradient using molecular proxies in view of land uses

Environmental occurrence and assessment of organic pollutants in surface sediments of South Peninsular Malaysia

Organic pollution continues to be an important worldwide obstacle for tackling health and environmental concerns that require ongoing and prompt response. To identify the LAB content levels as molecular indicators for sewage pollution, surface sediments had obtained from the South region of Malaysia. The origins of the LABs were identified using gas chromatography-mass spectrometry (GC-MS). ANOVA and a Pearson correlation coefficient at p < 0.05 were used in the statistical analyses of the differences between the research locations. Internal to external (I/E) ratio, homologs C13/C12, and long to short (L/S) chains are used to identify the effectiveness of wastewater treatments. According to statistical analysis, the range of LAB level at the stations was 67.4 to 188.7 ng g-1dw. A significant difference was observed between LAB homologs (p < 0.05), with a higher level of C13 in most of the stations. The computed LAB ratio (I/E), which varied from 1.6 to 2.7, revealed the released wastewater from primary and secondary sources. LAB degradation varied between 33 and 49% in the areas that were evaluated. The treatment system of wastewater requires to be further improved, and using LAB markers to track anthropogenic contamination is imperative.

An urban metabolism framework purpose to assess the dynamics of linear alkylbenzenes (LABs) discharge flows and driving forces at the city level in Guangdong province, China

Linear alkylbenzenes (LABs) are a class of molecular markers derived from anthropogenic activities. A comprehensive understanding of the mechanism that determines their entry into anthroposphere, in terms of magnitude and pathway, is the prerequisite to establish effective mitigation measures. This study develops a methodology framework to analyze the source-sink interactions and driving factors of the direct and indirect LAB discharges from production and living activities in Guangdong Province, China from 2004 to 2017. Results indicated that the total LAB discharges of Guangdong into the environment were averaged at 2.9 kt yr-1, of which 61.9% originated from the Pearl River Delta (PRD) urban agglomeration. An average proportion of 76.0% was discharged into water bodies with the remaining released into land bodied. From 2014 to 2017, the LAB discharges increased by seven times, resulting from the steady increase of urban residential sources, while contribution from industrial sources continuously declined during the studied period. Meanwhile, the discharging hotspots expanded from Guangzhou city to other super-cities around it, including Shenzhen and Dongguan. The other cities exhibited a decreasing trend in discharges as a function of distance from these hotspot cities. The multisectoral sources of LABs differed considerably among cities, and the source contribution of each city changed significantly with progressive urbanization. The factor decomposition analysis indicated that LAB discharges in PRD cities primarily contributed by the pollutant concentration and reflected the treatment structure, while peripheral cities of the PRD mainly contributed by the per capita consumption and pollutant discharge per unit of GDP. Overall, our results provide a scientific database and supports for the regional co-remediation of anthropogenic pollution.

Lateral distribution, environmental occurrence, and assessment of organic pollutants in surface sediments of the East Malaysia

One of the molecular chemical markers used to identify anthropogenic inputs is linear alkylbenzenes (LABs) that cause serious impacts in the bays and coastal ecosystems. The surface sediments samples collected from the East Malaysia, including Brunei bay to estimate the LABs concentration and distribution as molecular markers of anthropogenic indicators. Gas chromatography-mass spectrometry (GC-MS) was used after purification, fractionation the hydrocarbons in the sediment samples to identify the sources of LABs. The analysis of variance (ANOVA) and Pearson correlation coefficient were applied to analyze the difference between sampling stations' significance at p < 0.05. Long to short chains L/S, homologs C₁₃/C₁₂, and internal to external (I/E) congeners have used to assess the LABs degradation rates as well as the effectiveness of sewage treatment. Results of this study showed that the LABs concentration ranged between 7.1 to 41.3 ng g^-1 dw, in the investigated stations. The majority of sample sites exhibited a considerable input of C₁₃-LABs homologs, and LABs homologs differed significantly. The estimated LABs ratios (I/E), which ranged between 0.6 and 2.2, demonstrated the effluents with primary and less secondary sources are released into the bay waters. The degradation of LABs were up to 42% in the interrogated locations. The conclusion is that the wastewater treatment system needs to be improved, and that LABs molecular markers are highly effective in tracing anthropogenic sewage contamination.

Steroid-based tracing of sewage-sourced pollution of river water and wastewater treatment efficiency: Dissolved and suspended water phase distribution

In this work, the environmental distribution of steroid compounds and the level of sewage-derived contamination were assessed using sterol ratios in the confluence area of two major rivers in the Serbian capital, where raw sewage is discharged without any treatment. Special attention was paid to steroids partitioning between the dissolved and suspended phases of river and wastewater samples, since steroids tend to easily bind to particulate matter. The efficiency of sterol removal in two wastewater treatment plants in Serbia was also evaluated. Human/animal sterols coprostanol and cholesterol, and phytosterol β-sitosterol were the dominant compounds in all water samples. The sterol abundance pattern in river water was different from that in raw sewage, indicating a more pronounced biogenic input, as well as greater impact of wastewater discharges on the composition of the suspended phase. Severe contamination of the investigated area was determined, with the Danube being more contaminated than the Sava River due to different hydrodynamic conditions leading to significantly higher sterol levels in the suspended particulate matter. It was also shown that the greater part of human/animal sterols and phytosterols present in river water samples (83.0 ± 11.9 % and 87.1 ± 15.2 %) and wastewater samples (92.1 ± 6.8 % and 95.0 ± 5.7 %) was bound to suspended material compared to the dissolved phase, emphasizing the need to consider and analyze both water phases in the tracing of steroid-based environmental pollution in order to obtain a realistic picture of steroid contamination and their fate in the aquatic environment. A high removal rate (>98 %) of coprostanol and cholesterol during wastewater treatment was determined and only the coprostanol/(coprostanol + cholestanol) ratio was found to be sensitive enough to be affected by an improvement in the quality of treated wastewater.

Anthropogenic influences in a rapidly urbanizing area using linear alkylbenzenes and polycyclic aromatic hydrocarbons as tracers

Environmental molecular markers can be used to understand the sources, transport, and fate of pollutants. Furthermore, they can also be applied to assess the influences of anthropogenic activities and elucidate urbanization from different perspectives. In this study, the potential of linear alkylbenzenes (LABs) and polycyclic aromatic hydrocarbons (PAHs) as chemical indicators of urbanization was examined first. Overall, the concentrations of LABs and PAHs ranged from 5.49-148 ng/g (mean: 15.6, median: 9.33) and 3.61-4878 ng/g (mean: 181, median: 71.3), respectively. Owing to the different sources and input methods of these two substances in soil, the area-weighted median values for LABs were more suitable to assess the magnitude of contamination on the administrative scale. For PAHs, the average values were more practical. LAB (consumption-induced pollutants) and PAH (production-induced pollutants) concentrations exhibited good correlations with some indices for residential daily life and industrialization, which indicated that soil can be utilized to reveal multidimensional urbanization-environment relationships. Two different patterns, the inverted U-shaped pattern and the upward pattern, were employed to simulate the environment-urbanization relationships in Shenzhen, China, which indicated that raising the standard of living or industrialization had created different soil pollution. The environmental quality demand was more difficult to meet by changing the energy structure than by improving infrastructure.