The bioavailability of the metalloid arsenic (As) in paddy soil is controlled by microbial cycling of As and other elements such as iron (Fe) and sulfur (S), which are strongly influenced by water management in paddy fields. In this study, we evaluated how water management affects As bioavailability by growing rice plants in a geogenic As-contaminated soil. We determined As speciation in soil porewater and the diversity of the associated microbial community. Continuous flooding enhanced the release of Fe and As and increased arsenite (As(III)) and methylated As species concentrations in the rice grain compared with aerobic treatment. Total inorganic and organic As in the grain was 84% and 81% lower, respectively, in the aerobic treatment compared with the continuous flooding treatment. The amounts of Fe(III)-reducing bacteria (FeRB) increased in the flooded rhizosphere soil. The abundance of FeRB in the soil correlated with the dissolution of Fe and As. Among the As-transformation genes quantified, the aioA gene for As(III) oxidation and arsM gene for As(III) methylation were most abundant. The arsM copy number correlated positively with the levels of dsrB (dissimilatory (bi) sulfite reductase β-subunit), suggesting that dissimilatory sulfate-reducing bacteria (SRB) may play an important role in dimethylarsenate (DMAs(V)) production in soil. Our results show that decreased populations of rhizosphere FeRB and SRB contributed to a lower bioavailability of As, and decreased production of methylated arsenicals under oxic conditions.

In developing countries, many urban rivers are suffering from heavy contamination by untreated sewage, which implies great microbial risks. However, information regarding the bacterial pathogen diversity and distribution in urban rivers is highly limited. In this study, 41 water samples of fifteen rivers and eight samples from two sewage treatment plants in Changzhou City of Yangtze River Delta were sampled. Next-generation sequencing and a self-built reference pathogen database were used to investigate the diversity of enteric and environmental pathogens. The results indicated that the studied urban rivers were harboring diverse potential pathogen species, which primarily included enteric pathogens in Arcobacter and Bacteroides, and environmental pathogens in Acinetobacter, Aeromonas and Pseudomonas. Quantification of twelve pathogens/indicators of interest by qPCR showed that Escherichia coli, Enterococcus faecalis, Campylobacter jejuni, Arcobacter cryaerophilus, Acinetobacter johnsonii, Acinetobacter lwoffii and Aeromonas spp. were abundant, with median values ranging from 3.30 to 5.85 log10 copies/100 mL, while Salmonella, Legionella pheumophila, Mycobacterium avium, Pseudomonas aeruginosa and Staphylococcus aureus were infrequently quantified. The pollution of nutrients and human intestinal microorganisms indicated by specific markers were found to be prevalent but with different levels in the rivers. The correlation analyses revealed that the diversity (p < 0.01) and concentrations (p < 0.05) of the enteric pathogens highly correlated to the human fecal marker abundances, which indicated that the enteric pathogens in the urban rivers were likely to have originated from domestic sewage. The environmental pathogens, which are different from the enteric ones, showed various distribution patterns, and some of them were more abundant in the rivers of rich nutrient. Our findings provide a comprehensive understanding of the bacterial pathogen distribution and influencing factors in urban rivers that are impacted by domestic sewage, thereby establishing the foundation for urban water management.

Malaysia depends heavily on rivers as a source for water supply, irrigation, and sustaining the livelihood of local communities. The evolution of land use in urban areas due to rapid development and the continuous problem of illegal discharge have had a serious adverse impact on the health of the country's waterways. Klang River requires extensive rehabilitation and remediation before its water could be utilised for a variety of purposes. A reliable and rigorous remediation work plan is needed to identify the sources and locations of streams that are constantly polluted. This study attempts to investigate the feasibility of utilising a temporal and spatial risk quotient (RQ) based analysis to make an accurate assessment of the current condition of the tributaries in the Klang River catchment area. The study relies on existing data sets on Biochemical Oxygen Demand (BOD), Chemical Oxygen Demand (COD), Total Suspended Solids (TSS), and Ammonia (NH₃) to evaluate the water quality at thirty strategic locations. Analysis of ammonia pollution is not only based on the limit established for river health but was expanded to include the feasibility of using the water for water intake, recreational activities, and sustaining fish population. The temporal health of Klang River was evaluated using the Risk Matrix Approach (RMA) based on the frequency of RQ > 1 and associated colour-coded hazard impacts. By using the developed RMA, the hazard level for each parameter at each location was assessed and individually mapped using Geographic Information System (GIS). The developed risk hazard mapping has high potential as one of the essential tools in making decisions for a cost-effective river restoration and rehabilitation.

The present study evaluated the river water quality improvement by implementation of household-based biodigesters in vulnerability and poverty rural area, in Minas Gerais State-Brazil. For that, 78 household-based biodigesters were installed for domestic wastewater treatment. Wastewater was collected before and after treatment and the physicochemical parameters and pathogens removal (human adenovirus (HAdV), hepatitis A (HAV) virus, Salmonella sp. and Escherichia coli) were evaluated; Additionally, river water was sampled before and after the household-based biodigesters implementation, to verify the contamination reduction and the positive impact of domestic wastewater treatment on waterborne pathogen reduction, considering HAdV, HAV, Salmonella sp. and E. coli quantification. The applicability in real-scale of decentralized treatment systems using household-based biodigesters promoted reduction of 90, 99, 99.99 and 99.999% from HAV, Salmonella sp., E. coli and HAdV from domestic wastewater, respectively; The river water quality improvement before the wastewater treatment application was highlight in the present study, considering that the reduction of waterborne pathogens in this water in 90, 99.99 and 99.999% of E. coli, HAV and HAdV, respectively (Salmonella sp. was not detected in river water). In general, this is an important study for encouraging the decentralized sanitation in vulnerable and poverty area, as well in rural sites, considering the positive impact of this implementation on public health.

As the global population becomes more concentrated in urban areas, resource consumption, including access to pharmaceuticals, is increasing and chemical use is also increasingly concentrated. Unfortunately, implementation of waste management systems and wastewater treatment infrastructure is not yet meeting these global megatrends. Herein, pharmaceuticals are indicators of an urbanizing water cycle; antidepressants are among the most commonly studied classes of these contaminants of emerging concern. In the present study, we performed a unique global hazard assessment of selective serotonin reuptake inhibitors (SSRIs) in water matrices across geographic regions and for common wastewater treatment technologies. SSRIs in the environment have primarily been reported from Europe (50%) followed by North America (38%) and Asia-Pacific (10%). Minimal to no monitoring data exists for many developing regions of the world, including Africa and South America. From probabilistic environmental exposure distributions, 5th and 95th percentiles for all SSRIs across all geographic regions were 2.31 and 3022.1 ng/L for influent, 5.3 and 841.6 ng/L for effluent, 0.8 and 127.7 ng/L for freshwater, and 0.5 and 22.3 ng/L for coastal and marine systems, respectively. To estimate the potential hazards of SSRIs in the aquatic environment, percent exceedances of therapeutic hazard values of specific SSRIs, without recommended safety factors, were identified within and among geographic regions. For influent sewage and wastewater effluents, sertraline exceedances were observed 49% and 29% of the time, respectively, demonstrating the need to better understand emerging water quality hazards of SSRIs in urban freshwater and coastal ecosystems. This unique global review and analysis identified regions where more monitoring is necessary, and compounds requiring toxicological attention, particularly with increasing aquatic reports of behavioral perturbations elicited by SSRIs.

The United Nations recognised the transfer of invasive species across natural barriers as one of the greatest pressures to the world's oceans and seas. The BWM Convention sets the global standards on ballast water management (BWM) requirements, while recognising that regional and local specifics have to be considered for its effective implementation. In the Adriatic Sea cross-border activities were conducted to provide for essential information/data and tools to support a regionally coordinated implementation of the BWM Convention. This special issue contains 18 publications that include results and recommendations from studying the ballast water and management issues through sampling of ballast water on vessels, risk assessment for exemptions and BWM, biological and chemical port baseline surveys and monitoring conducted in ports along the Adriatic Sea coast, oceanographic conditions, ballast water sediment issues and their management in ports, and the implementation options of the BWM Convention through the Adriatic States' environmental law and institutions cooperation. Essential data and tools to support a regional approach in the implementation of the BWM Convention were provided, and are therefore available to the administrations of the Adriatic countries to enable protection of the Adriatic Sea environment, human health property and resources from negative impacts of ballast water being discharged in the area. Data, approaches and tools provided here may be helpful in any other region to support an effective BWM Convention implementation.

The Adriatic Sea, a semi-enclosed and vulnerable environment, deserves special attention regarding the risk of introducing Harmful Aquatic Organisms and Pathogens via ships' ballast water as new species findings occur at an alarming rate. This species introduction vector was addressed with the 2004 International Convention for the Control and Management of Ships' Ballast Water and Sediments, which entered into force in 2017. The efficient implementation of this convention calls for Adriatic States' cooperation on environmental specifics that have not been dealt with neither by national nor by international measures yet. Based on legal and institutional data gathered, and considering the regional maritime traffic and environmental specifics, this paper reveals that the integration of current environmental law commitments as well as a better dialogue between public institutions from shipping and environmental sectors may foster the implementation of ballast water management obligations through appropriate Adriatic States' cooperation.

Oxidant treatment of ballast water (BW) is commonly used in BW systems in order to minimize the transport of alien species. The release of disinfection by-products (DBPs) associated to the treatment of BW and cross-contamination of butyltin (BT) compounds through BW discharge is a topic of environmental concern. A chemical port baseline survey has been conducted in seven ports of the Adriatic Sea. Analysis have been performed on transplanted mussels, surface sediment, seawater, BW. Results showed an evidence of BT contamination, particularly in sediments, probably related to their illegal usage or to intensive shipping activities. Therefore, BW may act as a vector and contribute to re-buildup of BT contamination in the coastal regions.A baseline set of data concerning DBPs is provided, showing the preferential distribution of these compounds in the marine environment that will be useful for future considerations on monitoring and assessment of chemical contamination associated with BW.

The strategic location of Malaysia along the world's busiest trade waterways underscores the need to cope ballast water issues for both domestic and international shipping. The adoption of Ballast Water Management Convention 2004 (BWMC) by the International Maritime Organization is suitable for management plans intended to prevent the introduction of invasive species through ballast water discharge. Malaysia has ratified the BWMC in September 2010 and the Convention has come into force in September 2017. However up to now, the BWMC has not been fully implemented by Malaysia for ships operating in its waters. This paper analyse the headway in implementing the provisions of the BWMC in Malaysia as well as the issues and challenges encountered for the implementation. The paper concludes that Malaysian government should promulgate laws and policies to clearly communicate on ballast water issues to the shipping industry communities.

Ballast water discharges may cause negative impacts to aquatic ecosystems, human health and economic activities by the introduction of potentially harmful species. Fifty untreated ballast water tanks, ten in each port, were sampled in four Adriatic Italian ports and one Slovenian port. Salinity, temperature and fluorescence were measured on board. Faecal indicator bacteria (FIB), phyto- and zooplankton were qualitatively and quantitatively determined to identify the species assemblage arriving in ballast water. FIB exceeded the convention standard limits in 12% of the sampled tanks. Vibrio cholerae was not detected. The number of viable organisms in the size groups (minimum dimension) <50 and ≥10 μm and ≥50 μm resulted above the abundances required from the Ballast Water Management Convention in 55 and 86% of the samples, respectively. This is not surprising as unmanaged ballast waters were sampled. Some potentially toxic and non-indigenous species were observed in both phyto- and zooplankton assemblages.