Bacterial diversity across four drinking water distribution systems in Croatia: impacts of water management practices and disinfection by-products.

Several factors may impact bacterial diversity in drinking water distribution systems (DWDSs) including the origin of the raw water, the water treatment technologies, and the disinfection practices applied. 16S rRNA metabarcoding was used for the in-depth characterization of bacterial communities in the four studied Croatian DWDSs (A, B, C, D) two of which had residual disinfectant (A, B) and two were without (C, D), while only B utilized the conventional water treatment technology. Significantly higher diversity and species richness were evidenced in non-disinfected DWDSs (p<0.

Mixing of arsenic-rich groundwater and surface water in drinking water distribution systems: Implications for contaminants, disinfection byproducts and organic components.

The utilization of groundwaters containing high levels of arsenic (As) for drinking water purposes presents major health and economic challenges for water utilities. One low-cost approach is to mix arsenic-rich groundwater (GW) with arsenic-free surface waters (SW) to achieve acceptable As levels. In this study we investigated the effect of different mixing ratios on water quality in an eastern Croatian water distribution system (WDS).

Effects of changing supply water quality on drinking water distribution networks: Changes in NOM optical properties, disinfection byproduct formation, and Mn deposition and release.

Field studies were conducted in a Croatian city supplied by two distinct groundwater sources (referred to as A and B) to investigate both the effects of changing water source on the water quality in the drinking water supply system, as well as to further understand discoloration events that occurred in city locations that switched water from source A to B. The water treatment processes at site A were found to alter organic matter (OM) characteristics, removing humic substances while enhancing protein-derived (tryptophan) content. Although the humic-like component predominated in raw waters, microbially/protein-derived components were found to increase throughout the distribution networks of both systems.

Disinfection by-products in Croatian drinking water supplies with special emphasis on the water supply network in the city of Zagreb.

The occurrence of disinfection by-products (DBPs) was investigated in 48 drinking water systems across Croatia. Eleven DBPs were studied: chlorite (ClO), chlorate (ClO), four trihalomethanes (THMs), and five haloacetic acids (HAAs). Furthermore, an intensive sampling program was conducted in the distribution system in the city of Zagreb where, aside from DBP analyses, natural organic matter (NOM) was characterized using fluorescence spectroscopy.

[A model to diagnose occupational, asbestos-related pneumoconiosis and thickening of the pleura].

To correctly diagnose occupational asbestos-related disease, a specialist in occupational health has to answer a set of questions: (A) is the asbestos-related disease diagnosed by a specialist in pulmonology with the help of a radiologist and cardiologist occupational or non-occupational; (B) is the occupational asbestos-related disease caused by more than one source of asbestos dust, and, if it is, to what has of each of these sources contributed to the development of the disease; (C) how many functional disorders and symptoms (pulmonary, cardiac, chest pain, reactive fear from death, reactive psychoneurotic disorder in which fear is not the main symptom) has occupational asbestos-related disease produced and to what degree; (D) have these disorders and symptoms permanently reduced patient's work ability, and, if they have, can we speak of work disability; (E) have these disorders permanently reduced vital activity, and, if they have, can we speak of vital disability; and (F) does the patient suffer mental pain because of reduced vital activity, and if he does, what sort of pain. This approach should assume the form and content of an expert specialist opinion, that is, of a legal medical expertise and should rely on a more extensive medical and non-medical documentation than the one serving for therapeutic purposes. As such methodological approach is rarely met in practice, we have proposed a model that includes evaluation of cumulative exposure to asbestos dust, determination of work and vital disability, and evaluation of mental pain.